id
int64 12
1.07M
| title
stringlengths 1
124
| text
stringlengths 0
228k
| paragraphs
list | abstract
stringlengths 0
123k
| date_created
stringlengths 0
20
| date_modified
stringlengths 20
20
| templates
sequence | url
stringlengths 31
154
|
|---|---|---|---|---|---|---|---|---|
6,206 | Computable number | In mathematics, computable numbers are the real numbers that can be computed to within any desired precision by a finite, terminating algorithm. They are also known as the recursive numbers, effective numbers or the computable reals or recursive reals. The concept of a computable real number was introduced by Emile Borel in 1912, using the intuitive notion of computability available at the time.
Equivalent definitions can be given using μ-recursive functions, Turing machines, or λ-calculus as the formal representation of algorithms. The computable numbers form a real closed field and can be used in the place of real numbers for many, but not all, mathematical purposes.
In the following, Marvin Minsky defines the numbers to be computed in a manner similar to those defined by Alan Turing in 1936; i.e., as "sequences of digits interpreted as decimal fractions" between 0 and 1:
A computable number [is] one for which there is a Turing machine which, given n on its initial tape, terminates with the nth digit of that number [encoded on its tape].
The key notions in the definition are (1) that some n is specified at the start, (2) for any n the computation only takes a finite number of steps, after which the machine produces the desired output and terminates.
An alternate form of (2) – the machine successively prints all n of the digits on its tape, halting after printing the nth – emphasizes Minsky's observation: (3) That by use of a Turing machine, a finite definition – in the form of the machine's state table – is being used to define what is a potentially infinite string of decimal digits.
This is however not the modern definition which only requires the result be accurate to within any given accuracy. The informal definition above is subject to a rounding problem called the table-maker's dilemma whereas the modern definition is not.
A real number a is computable if it can be approximated by some computable function f : N → Z {\displaystyle f:\mathbb {N} \to \mathbb {Z} } in the following manner: given any positive integer n, the function produces an integer f(n) such that:
There are two similar definitions that are equivalent:
There is another equivalent definition of computable numbers via computable Dedekind cuts. A computable Dedekind cut is a computable function D {\displaystyle D\;} which when provided with a rational number r {\displaystyle r} as input returns D ( r ) = t r u e {\displaystyle D(r)=\mathrm {true} \;} or D ( r ) = f a l s e {\displaystyle D(r)=\mathrm {false} \;} , satisfying the following conditions:
An example is given by a program D that defines the cube root of 3. Assuming q > 0 {\displaystyle q>0\;} this is defined by:
A real number is computable if and only if there is a computable Dedekind cut D corresponding to it. The function D is unique for each computable number (although of course two different programs may provide the same function).
A complex number is called computable if its real and imaginary parts are computable.
Assigning a Gödel number to each Turing machine definition produces a subset S {\displaystyle S} of the natural numbers corresponding to the computable numbers and identifies a surjection from S {\displaystyle S} to the computable numbers. There are only countably many Turing machines, showing that the computable numbers are subcountable. The set S {\displaystyle S} of these Gödel numbers, however, is not computably enumerable (and consequently, neither are subsets of S {\displaystyle S} that are defined in terms of it). This is because there is no algorithm to determine which Gödel numbers correspond to Turing machines that produce computable reals. In order to produce a computable real, a Turing machine must compute a total function, but the corresponding decision problem is in Turing degree 0′′. Consequently, there is no surjective computable function from the natural numbers to the set S {\displaystyle S} of machines representing computable reals, and Cantor's diagonal argument cannot be used constructively to demonstrate uncountably many of them.
While the set of real numbers is uncountable, the set of computable numbers is classically countable and thus almost all real numbers are not computable. Here, for any given computable number x , {\displaystyle x,} the well ordering principle provides that there is a minimal element in S {\displaystyle S} which corresponds to x {\displaystyle x} , and therefore there exists a subset consisting of the minimal elements, on which the map is a bijection. The inverse of this bijection is an injection into the natural numbers of the computable numbers, proving that they are countable. But, again, this subset is not computable, even though the computable reals are themselves ordered.
The arithmetical operations on computable numbers are themselves computable in the sense that whenever real numbers a and b are computable then the following real numbers are also computable: a + b, a - b, ab, and a/b if b is nonzero. These operations are actually uniformly computable; for example, there is a Turing machine which on input (A,B, ϵ {\displaystyle \epsilon } ) produces output r, where A is the description of a Turing machine approximating a, B is the description of a Turing machine approximating b, and r is an ϵ {\displaystyle \epsilon } approximation of a+b.
The fact that computable real numbers form a field was first proved by Henry Gordon Rice in 1954.
Computable reals however do not form a computable field, because the definition of a computable field requires effective equality.
The order relation on the computable numbers is not computable. Let A be the description of a Turing machine approximating the number a {\displaystyle a} . Then there is no Turing machine which on input A outputs "YES" if a > 0 {\displaystyle a>0} and "NO" if a ≤ 0. {\displaystyle a\leq 0.} To see why, suppose the machine described by A keeps outputting 0 as ϵ {\displaystyle \epsilon } approximations. It is not clear how long to wait before deciding that the machine will never output an approximation which forces a to be positive. Thus the machine will eventually have to guess that the number will equal 0, in order to produce an output; the sequence may later become different from 0. This idea can be used to show that the machine is incorrect on some sequences if it computes a total function. A similar problem occurs when the computable reals are represented as Dedekind cuts. The same holds for the equality relation : the equality test is not computable.
While the full order relation is not computable, the restriction of it to pairs of unequal numbers is computable. That is, there is a program that takes as input two Turing machines A and B approximating numbers a {\displaystyle a} and b {\displaystyle b} , where a ≠ b {\displaystyle a\neq b} , and outputs whether a < b {\displaystyle a<b} or a > b . {\displaystyle a>b.} It is sufficient to use ϵ {\displaystyle \epsilon } -approximations where ϵ < | b − a | / 2 , {\displaystyle \epsilon <|b-a|/2,} so by taking increasingly small ϵ {\displaystyle \epsilon } (approaching 0), one eventually can decide whether a < b {\displaystyle a<b} or a > b . {\displaystyle a>b.}
The computable real numbers do not share all the properties of the real numbers used in analysis. For example, the least upper bound of a bounded increasing computable sequence of computable real numbers need not be a computable real number. A sequence with this property is known as a Specker sequence, as the first construction is due to Ernst Specker in 1949. Despite the existence of counterexamples such as these, parts of calculus and real analysis can be developed in the field of computable numbers, leading to the study of computable analysis.
Every computable number is arithmetically definable, but not vice versa. There are many arithmetically definable, noncomputable real numbers, including:
Both of these examples in fact define an infinite set of definable, uncomputable numbers, one for each Universal Turing machine. A real number is computable if and only if the set of natural numbers it represents (when written in binary and viewed as a characteristic function) is computable.
The set of computable real numbers (as well as every countable, densely ordered subset of computable reals without ends) is order-isomorphic to the set of rational numbers.
Turing's original paper defined computable numbers as follows:
A real number is computable if its digit sequence can be produced by some algorithm or Turing machine. The algorithm takes an integer n ≥ 1 {\displaystyle n\geq 1} as input and produces the n {\displaystyle n} -th digit of the real number's decimal expansion as output.
(The decimal expansion of a only refers to the digits following the decimal point.)
Turing was aware that this definition is equivalent to the ϵ {\displaystyle \epsilon } -approximation definition given above. The argument proceeds as follows: if a number is computable in the Turing sense, then it is also computable in the ϵ {\displaystyle \epsilon } sense: if n > log 10 ( 1 / ϵ ) {\displaystyle n>\log _{10}(1/\epsilon )} , then the first n digits of the decimal expansion for a provide an ϵ {\displaystyle \epsilon } approximation of a. For the converse, we pick an ϵ {\displaystyle \epsilon } computable real number a and generate increasingly precise approximations until the nth digit after the decimal point is certain. This always generates a decimal expansion equal to a but it may improperly end in an infinite sequence of 9's in which case it must have a finite (and thus computable) proper decimal expansion.
Unless certain topological properties of the real numbers are relevant, it is often more convenient to deal with elements of 2 ω {\displaystyle 2^{\omega }} (total 0,1 valued functions) instead of reals numbers in [ 0 , 1 ] {\displaystyle [0,1]} . The members of 2 ω {\displaystyle 2^{\omega }} can be identified with binary decimal expansions, but since the decimal expansions . d 1 d 2 … d n 0111 … {\displaystyle .d_{1}d_{2}\ldots d_{n}0111\ldots } and . d 1 d 2 … d n 10 {\displaystyle .d_{1}d_{2}\ldots d_{n}10} denote the same real number, the interval [ 0 , 1 ] {\displaystyle [0,1]} can only be bijectively (and homeomorphically under the subset topology) identified with the subset of 2 ω {\displaystyle 2^{\omega }} not ending in all 1's.
Note that this property of decimal expansions means that it is impossible to effectively identify the computable real numbers defined in terms of a decimal expansion and those defined in the ϵ {\displaystyle \epsilon } approximation sense. Hirst has shown that there is no algorithm which takes as input the description of a Turing machine which produces ϵ {\displaystyle \epsilon } approximations for the computable number a, and produces as output a Turing machine which enumerates the digits of a in the sense of Turing's definition. Similarly, it means that the arithmetic operations on the computable reals are not effective on their decimal representations as when adding decimal numbers. In order to produce one digit, it may be necessary to look arbitrarily far to the right to determine if there is a carry to the current location. This lack of uniformity is one reason why the contemporary definition of computable numbers uses ϵ {\displaystyle \epsilon } approximations rather than decimal expansions.
However, from a computability theoretic or measure theoretic perspective, the two structures 2 ω {\displaystyle 2^{\omega }} and [ 0 , 1 ] {\displaystyle [0,1]} are essentially identical. Thus, computability theorists often refer to members of 2 ω {\displaystyle 2^{\omega }} as reals. While 2 ω {\displaystyle 2^{\omega }} is totally disconnected, for questions about Π 1 0 {\displaystyle \Pi _{1}^{0}} classes or randomness it is easier to work in 2 ω {\displaystyle 2^{\omega }} .
Elements of ω ω {\displaystyle \omega ^{\omega }} are sometimes called reals as well and though containing a homeomorphic image of R {\displaystyle \mathbb {R} } , ω ω {\displaystyle \omega ^{\omega }} isn't even locally compact (in addition to being totally disconnected). This leads to genuine differences in the computational properties. For instance the x ∈ R {\displaystyle x\in \mathbb {R} } satisfying ∀ ( n ∈ ω ) ϕ ( x , n ) {\displaystyle \forall (n\in \omega )\phi (x,n)} , with ϕ ( x , n ) {\displaystyle \phi (x,n)} quantifier free, must be computable while the unique x ∈ ω ω {\displaystyle x\in \omega ^{\omega }} satisfying a universal formula may have an arbitrarily high position in the hyperarithmetic hierarchy.
The computable numbers include the specific real numbers which appear in practice, including all real algebraic numbers, as well as e, π, and many other transcendental numbers. Though the computable reals exhaust those reals we can calculate or approximate, the assumption that all reals are computable leads to substantially different conclusions about the real numbers. The question naturally arises of whether it is possible to dispose of the full set of reals and use computable numbers for all of mathematics. This idea is appealing from a constructivist point of view, and has been pursued by what Errett Bishop and Fred Richman call the Russian school of constructive mathematics.
To actually develop analysis over computable numbers, some care must be taken. For example, if one uses the classical definition of a sequence, the set of computable numbers is not closed under the basic operation of taking the supremum of a bounded sequence (for example, consider a Specker sequence, see the section above). This difficulty is addressed by considering only sequences which have a computable modulus of convergence. The resulting mathematical theory is called computable analysis.
Computer packages representing real numbers as programs computing approximations have been proposed as early as 1985, under the name "exact arithmetic". Modern examples include the CoRN library (Coq), and the RealLib package (C++). A related line of work is based on taking a real RAM program and running it with rational or floating-point numbers of sufficient precision, such as the iRRAM package. | [
{
"paragraph_id": 0,
"text": "In mathematics, computable numbers are the real numbers that can be computed to within any desired precision by a finite, terminating algorithm. They are also known as the recursive numbers, effective numbers or the computable reals or recursive reals. The concept of a computable real number was introduced by Emile Borel in 1912, using the intuitive notion of computability available at the time.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Equivalent definitions can be given using μ-recursive functions, Turing machines, or λ-calculus as the formal representation of algorithms. The computable numbers form a real closed field and can be used in the place of real numbers for many, but not all, mathematical purposes.",
"title": ""
},
{
"paragraph_id": 2,
"text": "In the following, Marvin Minsky defines the numbers to be computed in a manner similar to those defined by Alan Turing in 1936; i.e., as \"sequences of digits interpreted as decimal fractions\" between 0 and 1:",
"title": "Informal definition using a Turing machine as example"
},
{
"paragraph_id": 3,
"text": "A computable number [is] one for which there is a Turing machine which, given n on its initial tape, terminates with the nth digit of that number [encoded on its tape].",
"title": "Informal definition using a Turing machine as example"
},
{
"paragraph_id": 4,
"text": "The key notions in the definition are (1) that some n is specified at the start, (2) for any n the computation only takes a finite number of steps, after which the machine produces the desired output and terminates.",
"title": "Informal definition using a Turing machine as example"
},
{
"paragraph_id": 5,
"text": "An alternate form of (2) – the machine successively prints all n of the digits on its tape, halting after printing the nth – emphasizes Minsky's observation: (3) That by use of a Turing machine, a finite definition – in the form of the machine's state table – is being used to define what is a potentially infinite string of decimal digits.",
"title": "Informal definition using a Turing machine as example"
},
{
"paragraph_id": 6,
"text": "This is however not the modern definition which only requires the result be accurate to within any given accuracy. The informal definition above is subject to a rounding problem called the table-maker's dilemma whereas the modern definition is not.",
"title": "Informal definition using a Turing machine as example"
},
{
"paragraph_id": 7,
"text": "A real number a is computable if it can be approximated by some computable function f : N → Z {\\displaystyle f:\\mathbb {N} \\to \\mathbb {Z} } in the following manner: given any positive integer n, the function produces an integer f(n) such that:",
"title": "Formal definition"
},
{
"paragraph_id": 8,
"text": "There are two similar definitions that are equivalent:",
"title": "Formal definition"
},
{
"paragraph_id": 9,
"text": "There is another equivalent definition of computable numbers via computable Dedekind cuts. A computable Dedekind cut is a computable function D {\\displaystyle D\\;} which when provided with a rational number r {\\displaystyle r} as input returns D ( r ) = t r u e {\\displaystyle D(r)=\\mathrm {true} \\;} or D ( r ) = f a l s e {\\displaystyle D(r)=\\mathrm {false} \\;} , satisfying the following conditions:",
"title": "Formal definition"
},
{
"paragraph_id": 10,
"text": "An example is given by a program D that defines the cube root of 3. Assuming q > 0 {\\displaystyle q>0\\;} this is defined by:",
"title": "Formal definition"
},
{
"paragraph_id": 11,
"text": "A real number is computable if and only if there is a computable Dedekind cut D corresponding to it. The function D is unique for each computable number (although of course two different programs may provide the same function).",
"title": "Formal definition"
},
{
"paragraph_id": 12,
"text": "A complex number is called computable if its real and imaginary parts are computable.",
"title": "Formal definition"
},
{
"paragraph_id": 13,
"text": "Assigning a Gödel number to each Turing machine definition produces a subset S {\\displaystyle S} of the natural numbers corresponding to the computable numbers and identifies a surjection from S {\\displaystyle S} to the computable numbers. There are only countably many Turing machines, showing that the computable numbers are subcountable. The set S {\\displaystyle S} of these Gödel numbers, however, is not computably enumerable (and consequently, neither are subsets of S {\\displaystyle S} that are defined in terms of it). This is because there is no algorithm to determine which Gödel numbers correspond to Turing machines that produce computable reals. In order to produce a computable real, a Turing machine must compute a total function, but the corresponding decision problem is in Turing degree 0′′. Consequently, there is no surjective computable function from the natural numbers to the set S {\\displaystyle S} of machines representing computable reals, and Cantor's diagonal argument cannot be used constructively to demonstrate uncountably many of them.",
"title": "Properties"
},
{
"paragraph_id": 14,
"text": "While the set of real numbers is uncountable, the set of computable numbers is classically countable and thus almost all real numbers are not computable. Here, for any given computable number x , {\\displaystyle x,} the well ordering principle provides that there is a minimal element in S {\\displaystyle S} which corresponds to x {\\displaystyle x} , and therefore there exists a subset consisting of the minimal elements, on which the map is a bijection. The inverse of this bijection is an injection into the natural numbers of the computable numbers, proving that they are countable. But, again, this subset is not computable, even though the computable reals are themselves ordered.",
"title": "Properties"
},
{
"paragraph_id": 15,
"text": "The arithmetical operations on computable numbers are themselves computable in the sense that whenever real numbers a and b are computable then the following real numbers are also computable: a + b, a - b, ab, and a/b if b is nonzero. These operations are actually uniformly computable; for example, there is a Turing machine which on input (A,B, ϵ {\\displaystyle \\epsilon } ) produces output r, where A is the description of a Turing machine approximating a, B is the description of a Turing machine approximating b, and r is an ϵ {\\displaystyle \\epsilon } approximation of a+b.",
"title": "Properties"
},
{
"paragraph_id": 16,
"text": "The fact that computable real numbers form a field was first proved by Henry Gordon Rice in 1954.",
"title": "Properties"
},
{
"paragraph_id": 17,
"text": "Computable reals however do not form a computable field, because the definition of a computable field requires effective equality.",
"title": "Properties"
},
{
"paragraph_id": 18,
"text": "The order relation on the computable numbers is not computable. Let A be the description of a Turing machine approximating the number a {\\displaystyle a} . Then there is no Turing machine which on input A outputs \"YES\" if a > 0 {\\displaystyle a>0} and \"NO\" if a ≤ 0. {\\displaystyle a\\leq 0.} To see why, suppose the machine described by A keeps outputting 0 as ϵ {\\displaystyle \\epsilon } approximations. It is not clear how long to wait before deciding that the machine will never output an approximation which forces a to be positive. Thus the machine will eventually have to guess that the number will equal 0, in order to produce an output; the sequence may later become different from 0. This idea can be used to show that the machine is incorrect on some sequences if it computes a total function. A similar problem occurs when the computable reals are represented as Dedekind cuts. The same holds for the equality relation : the equality test is not computable.",
"title": "Properties"
},
{
"paragraph_id": 19,
"text": "While the full order relation is not computable, the restriction of it to pairs of unequal numbers is computable. That is, there is a program that takes as input two Turing machines A and B approximating numbers a {\\displaystyle a} and b {\\displaystyle b} , where a ≠ b {\\displaystyle a\\neq b} , and outputs whether a < b {\\displaystyle a<b} or a > b . {\\displaystyle a>b.} It is sufficient to use ϵ {\\displaystyle \\epsilon } -approximations where ϵ < | b − a | / 2 , {\\displaystyle \\epsilon <|b-a|/2,} so by taking increasingly small ϵ {\\displaystyle \\epsilon } (approaching 0), one eventually can decide whether a < b {\\displaystyle a<b} or a > b . {\\displaystyle a>b.}",
"title": "Properties"
},
{
"paragraph_id": 20,
"text": "The computable real numbers do not share all the properties of the real numbers used in analysis. For example, the least upper bound of a bounded increasing computable sequence of computable real numbers need not be a computable real number. A sequence with this property is known as a Specker sequence, as the first construction is due to Ernst Specker in 1949. Despite the existence of counterexamples such as these, parts of calculus and real analysis can be developed in the field of computable numbers, leading to the study of computable analysis.",
"title": "Properties"
},
{
"paragraph_id": 21,
"text": "Every computable number is arithmetically definable, but not vice versa. There are many arithmetically definable, noncomputable real numbers, including:",
"title": "Properties"
},
{
"paragraph_id": 22,
"text": "Both of these examples in fact define an infinite set of definable, uncomputable numbers, one for each Universal Turing machine. A real number is computable if and only if the set of natural numbers it represents (when written in binary and viewed as a characteristic function) is computable.",
"title": "Properties"
},
{
"paragraph_id": 23,
"text": "The set of computable real numbers (as well as every countable, densely ordered subset of computable reals without ends) is order-isomorphic to the set of rational numbers.",
"title": "Properties"
},
{
"paragraph_id": 24,
"text": "Turing's original paper defined computable numbers as follows:",
"title": "Digit strings and the Cantor and Baire spaces"
},
{
"paragraph_id": 25,
"text": "A real number is computable if its digit sequence can be produced by some algorithm or Turing machine. The algorithm takes an integer n ≥ 1 {\\displaystyle n\\geq 1} as input and produces the n {\\displaystyle n} -th digit of the real number's decimal expansion as output.",
"title": "Digit strings and the Cantor and Baire spaces"
},
{
"paragraph_id": 26,
"text": "(The decimal expansion of a only refers to the digits following the decimal point.)",
"title": "Digit strings and the Cantor and Baire spaces"
},
{
"paragraph_id": 27,
"text": "Turing was aware that this definition is equivalent to the ϵ {\\displaystyle \\epsilon } -approximation definition given above. The argument proceeds as follows: if a number is computable in the Turing sense, then it is also computable in the ϵ {\\displaystyle \\epsilon } sense: if n > log 10 ( 1 / ϵ ) {\\displaystyle n>\\log _{10}(1/\\epsilon )} , then the first n digits of the decimal expansion for a provide an ϵ {\\displaystyle \\epsilon } approximation of a. For the converse, we pick an ϵ {\\displaystyle \\epsilon } computable real number a and generate increasingly precise approximations until the nth digit after the decimal point is certain. This always generates a decimal expansion equal to a but it may improperly end in an infinite sequence of 9's in which case it must have a finite (and thus computable) proper decimal expansion.",
"title": "Digit strings and the Cantor and Baire spaces"
},
{
"paragraph_id": 28,
"text": "Unless certain topological properties of the real numbers are relevant, it is often more convenient to deal with elements of 2 ω {\\displaystyle 2^{\\omega }} (total 0,1 valued functions) instead of reals numbers in [ 0 , 1 ] {\\displaystyle [0,1]} . The members of 2 ω {\\displaystyle 2^{\\omega }} can be identified with binary decimal expansions, but since the decimal expansions . d 1 d 2 … d n 0111 … {\\displaystyle .d_{1}d_{2}\\ldots d_{n}0111\\ldots } and . d 1 d 2 … d n 10 {\\displaystyle .d_{1}d_{2}\\ldots d_{n}10} denote the same real number, the interval [ 0 , 1 ] {\\displaystyle [0,1]} can only be bijectively (and homeomorphically under the subset topology) identified with the subset of 2 ω {\\displaystyle 2^{\\omega }} not ending in all 1's.",
"title": "Digit strings and the Cantor and Baire spaces"
},
{
"paragraph_id": 29,
"text": "Note that this property of decimal expansions means that it is impossible to effectively identify the computable real numbers defined in terms of a decimal expansion and those defined in the ϵ {\\displaystyle \\epsilon } approximation sense. Hirst has shown that there is no algorithm which takes as input the description of a Turing machine which produces ϵ {\\displaystyle \\epsilon } approximations for the computable number a, and produces as output a Turing machine which enumerates the digits of a in the sense of Turing's definition. Similarly, it means that the arithmetic operations on the computable reals are not effective on their decimal representations as when adding decimal numbers. In order to produce one digit, it may be necessary to look arbitrarily far to the right to determine if there is a carry to the current location. This lack of uniformity is one reason why the contemporary definition of computable numbers uses ϵ {\\displaystyle \\epsilon } approximations rather than decimal expansions.",
"title": "Digit strings and the Cantor and Baire spaces"
},
{
"paragraph_id": 30,
"text": "However, from a computability theoretic or measure theoretic perspective, the two structures 2 ω {\\displaystyle 2^{\\omega }} and [ 0 , 1 ] {\\displaystyle [0,1]} are essentially identical. Thus, computability theorists often refer to members of 2 ω {\\displaystyle 2^{\\omega }} as reals. While 2 ω {\\displaystyle 2^{\\omega }} is totally disconnected, for questions about Π 1 0 {\\displaystyle \\Pi _{1}^{0}} classes or randomness it is easier to work in 2 ω {\\displaystyle 2^{\\omega }} .",
"title": "Digit strings and the Cantor and Baire spaces"
},
{
"paragraph_id": 31,
"text": "Elements of ω ω {\\displaystyle \\omega ^{\\omega }} are sometimes called reals as well and though containing a homeomorphic image of R {\\displaystyle \\mathbb {R} } , ω ω {\\displaystyle \\omega ^{\\omega }} isn't even locally compact (in addition to being totally disconnected). This leads to genuine differences in the computational properties. For instance the x ∈ R {\\displaystyle x\\in \\mathbb {R} } satisfying ∀ ( n ∈ ω ) ϕ ( x , n ) {\\displaystyle \\forall (n\\in \\omega )\\phi (x,n)} , with ϕ ( x , n ) {\\displaystyle \\phi (x,n)} quantifier free, must be computable while the unique x ∈ ω ω {\\displaystyle x\\in \\omega ^{\\omega }} satisfying a universal formula may have an arbitrarily high position in the hyperarithmetic hierarchy.",
"title": "Digit strings and the Cantor and Baire spaces"
},
{
"paragraph_id": 32,
"text": "The computable numbers include the specific real numbers which appear in practice, including all real algebraic numbers, as well as e, π, and many other transcendental numbers. Though the computable reals exhaust those reals we can calculate or approximate, the assumption that all reals are computable leads to substantially different conclusions about the real numbers. The question naturally arises of whether it is possible to dispose of the full set of reals and use computable numbers for all of mathematics. This idea is appealing from a constructivist point of view, and has been pursued by what Errett Bishop and Fred Richman call the Russian school of constructive mathematics.",
"title": "Use in place of the reals"
},
{
"paragraph_id": 33,
"text": "To actually develop analysis over computable numbers, some care must be taken. For example, if one uses the classical definition of a sequence, the set of computable numbers is not closed under the basic operation of taking the supremum of a bounded sequence (for example, consider a Specker sequence, see the section above). This difficulty is addressed by considering only sequences which have a computable modulus of convergence. The resulting mathematical theory is called computable analysis.",
"title": "Use in place of the reals"
},
{
"paragraph_id": 34,
"text": "Computer packages representing real numbers as programs computing approximations have been proposed as early as 1985, under the name \"exact arithmetic\". Modern examples include the CoRN library (Coq), and the RealLib package (C++). A related line of work is based on taking a real RAM program and running it with rational or floating-point numbers of sufficient precision, such as the iRRAM package.",
"title": "Implementations of exact arithmetic"
}
] | In mathematics, computable numbers are the real numbers that can be computed to within any desired precision by a finite, terminating algorithm. They are also known as the recursive numbers, effective numbers or the computable reals or recursive reals. The concept of a computable real number was introduced by Emile Borel in 1912, using the intuitive notion of computability available at the time. Equivalent definitions can be given using μ-recursive functions, Turing machines, or λ-calculus as the formal representation of algorithms. The computable numbers form a real closed field and can be used in the place of real numbers for many, but not all, mathematical purposes. | 2001-08-24T16:20:07Z | 2023-09-23T07:27:09Z | [
"Template:Blockquote",
"Template:Quote",
"Template:Cite book",
"Template:Cite web",
"Template:Short description",
"Template:Distinguish",
"Template:Refbegin",
"Template:Number systems",
"Template:Sfnp",
"Template:Cn",
"Template:Proper name",
"Template:Refend",
"Template:Reflist",
"Template:Citation",
"Template:Cite journal"
] | https://en.wikipedia.org/wiki/Computable_number |
6,207 | Electric current | An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge carriers, which may be one of several types of particles, depending on the conductor. In electric circuits the charge carriers are often electrons moving through a wire. In semiconductors they can be electrons or holes. In an electrolyte the charge carriers are ions, while in plasma, an ionized gas, they are ions and electrons.
The SI unit of electric current is the ampere, or amp, which is the flow of electric charge across a surface at the rate of one coulomb per second. The ampere (symbol: A) is an SI base unit. Electric current is measured using a device called an ammeter.
Electric currents create magnetic fields, which are used in motors, generators, inductors, and transformers. In ordinary conductors, they cause Joule heating, which creates light in incandescent light bulbs. Time-varying currents emit electromagnetic waves, which are used in telecommunications to broadcast information.
The conventional symbol for current is I, which originates from the French phrase intensité du courant, (current intensity). Current intensity is often referred to simply as current. The I symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating Ampère's force law (1820). The notation travelled from France to Great Britain, where it became standard, although at least one journal did not change from using C to I until 1896.
The conventional direction of current, also known as conventional current, is arbitrarily defined as the direction in which positive charges flow. In a conductive material, the moving charged particles that constitute the electric current are called charge carriers. In metals, which make up the wires and other conductors in most electrical circuits, the positively charged atomic nuclei of the atoms are held in a fixed position, and the negatively charged electrons are the charge carriers, free to move about in the metal. In other materials, notably the semiconductors, the charge carriers can be positive or negative, depending on the dopant used. Positive and negative charge carriers may even be present at the same time, as happens in an electrolyte in an electrochemical cell.
A flow of positive charges gives the same electric current, and has the same effect in a circuit, as an equal flow of negative charges in the opposite direction. Since current can be the flow of either positive or negative charges, or both, a convention is needed for the direction of current that is independent of the type of charge carriers. Negatively charged carriers, such as the electrons (the charge carriers in metal wires and many other electronic circuit components), therefore flow in the opposite direction of conventional current flow in an electrical circuit.
A current in a wire or circuit element can flow in either of two directions. When defining a variable I {\displaystyle I} to represent the current, the direction representing positive current must be specified, usually by an arrow on the circuit schematic diagram. This is called the reference direction of the current I {\displaystyle I} . When analyzing electrical circuits, the actual direction of current through a specific circuit element is usually unknown until the analysis is completed. Consequently, the reference directions of currents are often assigned arbitrarily. When the circuit is solved, a negative value for the current implies the actual direction of current through that circuit element is opposite that of the chosen reference direction.
Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equation that describes this relationship:
where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms. More specifically, Ohm's law states that the R in this relation is constant, independent of the current.
In alternating current (AC) systems, the movement of electric charge periodically reverses direction. AC is the form of electric power most commonly delivered to businesses and residences. The usual waveform of an AC power circuit is a sine wave, though certain applications use alternative waveforms, such as triangular or square waves. Audio and radio signals carried on electrical wires are also examples of alternating current. An important goal in these applications is recovery of information encoded (or modulated) onto the AC signal.
In contrast, direct current (DC) refers to a system in which the movement of electric charge in only one direction (sometimes called unidirectional flow). Direct current is produced by sources such as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Alternating current can also be converted to direct current through use of a rectifier. Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. An old name for direct current was galvanic current.
Natural observable examples of electric current include lightning, static electric discharge, and the solar wind, the source of the polar auroras.
Man-made occurrences of electric current include the flow of conduction electrons in metal wires such as the overhead power lines that deliver electrical energy across long distances and the smaller wires within electrical and electronic equipment. Eddy currents are electric currents that occur in conductors exposed to changing magnetic fields. Similarly, electric currents occur, particularly in the surface, of conductors exposed to electromagnetic waves. When oscillating electric currents flow at the correct voltages within radio antennas, radio waves are generated.
In electronics, other forms of electric current include the flow of electrons through resistors or through the vacuum in a vacuum tube, the flow of ions inside a battery, and the flow of holes within metals and semiconductors.
A biological example of current is the flow of ions in neurons and nerves, responsible for both thought and sensory perception.
Current can be measured using an ammeter.
Electric current can be directly measured with a galvanometer, but this method involves breaking the electrical circuit, which is sometimes inconvenient.
Current can also be measured without breaking the circuit by detecting the magnetic field associated with the current. Devices, at the circuit level, use various techniques to measure current:
Joule heating, also known as ohmic heating and resistive heating, is the process of power dissipation by which the passage of an electric current through a conductor increases the internal energy of the conductor, converting thermodynamic work into heat. The phenomenon was first studied by James Prescott Joule in 1841. Joule immersed a length of wire in a fixed mass of water and measured the temperature rise due to a known current through the wire for a 30 minute period. By varying the current and the length of the wire he deduced that the heat produced was proportional to the square of the current multiplied by the electrical resistance of the wire.
This relationship is known as Joule's Law. The SI unit of energy was subsequently named the joule and given the symbol J. The commonly known SI unit of power, the watt (symbol: W), is equivalent to one joule per second.
In an electromagnet a coil of wires behaves like a magnet when an electric current flows through it. When the current is switched off, the coil loses its magnetism immediately. Electric current produces a magnetic field. The magnetic field can be visualized as a pattern of circular field lines surrounding the wire that persists as long as there is current.
Magnetic fields can also be used to make electric currents. When a changing magnetic field is applied to a conductor, an electromotive force (EMF) is induced, which starts an electric current, when there is a suitable path.
When an electric current flows in a suitably shaped conductor at radio frequencies, radio waves can be generated. These travel at the speed of light and can cause electric currents in distant conductors.
In metallic solids, electric charge flows by means of electrons, from lower to higher electrical potential. In other media, any stream of charged objects (ions, for example) may constitute an electric current. To provide a definition of current independent of the type of charge carriers, conventional current is defined as moving in the same direction as the positive charge flow. So, in metals where the charge carriers (electrons) are negative, conventional current is in the opposite direction to the overall electron movement. In conductors where the charge carriers are positive, conventional current is in the same direction as the charge carriers.
In a vacuum, a beam of ions or electrons may be formed. In other conductive materials, the electric current is due to the flow of both positively and negatively charged particles at the same time. In still others, the current is entirely due to positive charge flow. For example, the electric currents in electrolytes are flows of positively and negatively charged ions. In a common lead-acid electrochemical cell, electric currents are composed of positive hydronium ions flowing in one direction, and negative sulfate ions flowing in the other. Electric currents in sparks or plasma are flows of electrons as well as positive and negative ions. In ice and in certain solid electrolytes, the electric current is entirely composed of flowing ions.
In a metal, some of the outer electrons in each atom are not bound to the individual molecules as they are in molecular solids, or in full bands as they are in insulating materials, but are free to move within the metal lattice. These conduction electrons can serve as charge carriers, carrying a current. Metals are particularly conductive because there are many of these free electrons. With no external electric field applied, these electrons move about randomly due to thermal energy but, on average, there is zero net current within the metal. At room temperature, the average speed of these random motions is 10 metres per second. Given a surface through which a metal wire passes, electrons move in both directions across the surface at an equal rate. As George Gamow wrote in his popular science book, One, Two, Three...Infinity (1947), "The metallic substances differ from all other materials by the fact that the outer shells of their atoms are bound rather loosely, and often let one of their electrons go free. Thus the interior of a metal is filled up with a large number of unattached electrons that travel aimlessly around like a crowd of displaced persons. When a metal wire is subjected to electric force applied on its opposite ends, these free electrons rush in the direction of the force, thus forming what we call an electric current."
When a metal wire is connected across the two terminals of a DC voltage source such as a battery, the source places an electric field across the conductor. The moment contact is made, the free electrons of the conductor are forced to drift toward the positive terminal under the influence of this field. The free electrons are therefore the charge carrier in a typical solid conductor.
For a steady flow of charge through a surface, the current I (in amperes) can be calculated with the following equation:
where Q is the electric charge transferred through the surface over a time t. If Q and t are measured in coulombs and seconds respectively, I is in amperes.
More generally, electric current can be represented as the rate at which charge flows through a given surface as:
Electric currents in electrolytes are flows of electrically charged particles (ions). For example, if an electric field is placed across a solution of Na and Cl (and conditions are right) the sodium ions move towards the negative electrode (cathode), while the chloride ions move towards the positive electrode (anode). Reactions take place at both electrode surfaces, neutralizing each ion.
Water-ice and certain solid electrolytes called proton conductors contain positive hydrogen ions ("protons") that are mobile. In these materials, electric currents are composed of moving protons, as opposed to the moving electrons in metals.
In certain electrolyte mixtures, brightly coloured ions are the moving electric charges. The slow progress of the colour makes the current visible.
In air and other ordinary gases below the breakdown field, the dominant source of electrical conduction is via relatively few mobile ions produced by radioactive gases, ultraviolet light, or cosmic rays. Since the electrical conductivity is low, gases are dielectrics or insulators. However, once the applied electric field approaches the breakdown value, free electrons become sufficiently accelerated by the electric field to create additional free electrons by colliding, and ionizing, neutral gas atoms or molecules in a process called avalanche breakdown. The breakdown process forms a plasma that contains enough mobile electrons and positive ions to make it an electrical conductor. In the process, it forms a light emitting conductive path, such as a spark, arc or lightning.
Plasma is the state of matter where some of the electrons in a gas are stripped or "ionized" from their molecules or atoms. A plasma can be formed by high temperature, or by application of a high electric or alternating magnetic field as noted above. Due to their lower mass, the electrons in a plasma accelerate more quickly in response to an electric field than the heavier positive ions, and hence carry the bulk of the current. The free ions recombine to create new chemical compounds (for example, breaking atmospheric oxygen into single oxygen [O2 → 2O], which then recombine creating ozone [O3]).
Since a "perfect vacuum" contains no charged particles, it normally behaves as a perfect insulator. However, metal electrode surfaces can cause a region of the vacuum to become conductive by injecting free electrons or ions through either field electron emission or thermionic emission. Thermionic emission occurs when the thermal energy exceeds the metal's work function, while field electron emission occurs when the electric field at the surface of the metal is high enough to cause tunneling, which results in the ejection of free electrons from the metal into the vacuum. Externally heated electrodes are often used to generate an electron cloud as in the filament or indirectly heated cathode of vacuum tubes. Cold electrodes can also spontaneously produce electron clouds via thermionic emission when small incandescent regions (called cathode spots or anode spots) are formed. These are incandescent regions of the electrode surface that are created by a localized high current. These regions may be initiated by field electron emission, but are then sustained by localized thermionic emission once a vacuum arc forms. These small electron-emitting regions can form quite rapidly, even explosively, on a metal surface subjected to a high electrical field. Vacuum tubes and sprytrons are some of the electronic switching and amplifying devices based on vacuum conductivity.
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.
In a semiconductor it is sometimes useful to think of the current as due to the flow of positive "holes" (the mobile positive charge carriers that are places where the semiconductor crystal is missing a valence electron). This is the case in a p-type semiconductor. A semiconductor has electrical conductivity intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 10 to 10 siemens per centimeter (S⋅cm).
In the classic crystalline semiconductors, electrons can have energies only within certain bands (i.e. ranges of levels of energy). Energetically, these bands are located between the energy of the ground state, the state in which electrons are tightly bound to the atomic nuclei of the material, and the free electron energy, the latter describing the energy required for an electron to escape entirely from the material. The energy bands each correspond to many discrete quantum states of the electrons, and most of the states with low energy (closer to the nucleus) are occupied, up to a particular band called the valence band. Semiconductors and insulators are distinguished from metals because the valence band in any given metal is nearly filled with electrons under usual operating conditions, while very few (semiconductor) or virtually none (insulator) of them are available in the conduction band, the band immediately above the valence band.
The ease of exciting electrons in the semiconductor from the valence band to the conduction band depends on the band gap between the bands. The size of this energy band gap serves as an arbitrary dividing line (roughly 4 eV) between semiconductors and insulators.
With covalent bonds, an electron moves by hopping to a neighboring bond. The Pauli exclusion principle requires that the electron be lifted into the higher anti-bonding state of that bond. For delocalized states, for example in one dimension – that is in a nanowire, for every energy there is a state with electrons flowing in one direction and another state with the electrons flowing in the other. For a net current to flow, more states for one direction than for the other direction must be occupied. For this to occur, energy is required, as in the semiconductor the next higher states lie above the band gap. Often this is stated as: full bands do not contribute to the electrical conductivity. However, as a semiconductor's temperature rises above absolute zero, there is more energy in the semiconductor to spend on lattice vibration and on exciting electrons into the conduction band. The current-carrying electrons in the conduction band are known as free electrons, though they are often simply called electrons if that is clear in context.
Current density is the rate at which charge passes through a chosen unit area. It is defined as a vector whose magnitude is the current per unit cross-sectional area. As discussed in Reference direction, the direction is arbitrary. Conventionally, if the moving charges are positive, then the current density has the same sign as the velocity of the charges. For negative charges, the sign of the current density is opposite to the velocity of the charges. In SI units, current density (symbol: j) is expressed in the SI base units of amperes per square metre.
In linear materials such as metals, and under low frequencies, the current density across the conductor surface is uniform. In such conditions, Ohm's law states that the current is directly proportional to the potential difference between two ends (across) of that metal (ideal) resistor (or other ohmic device):
where I {\displaystyle I} is the current, measured in amperes; V {\displaystyle V} is the potential difference, measured in volts; and R {\displaystyle R} is the resistance, measured in ohms. For alternating currents, especially at higher frequencies, skin effect causes the current to spread unevenly across the conductor cross-section, with higher density near the surface, thus increasing the apparent resistance.
The mobile charged particles within a conductor move constantly in random directions, like the particles of a gas. (More accurately, a Fermi gas.) To create a net flow of charge, the particles must also move together with an average drift rate. Electrons are the charge carriers in most metals and they follow an erratic path, bouncing from atom to atom, but generally drifting in the opposite direction of the electric field. The speed they drift at can be calculated from the equation:
where
Typically, electric charges in solids flow slowly. For example, in a copper wire of cross-section 0.5 mm, carrying a current of 5 A, the drift velocity of the electrons is on the order of a millimetre per second. To take a different example, in the near-vacuum inside a cathode-ray tube, the electrons travel in near-straight lines at about a tenth of the speed of light.
Any accelerating electric charge, and therefore any changing electric current, gives rise to an electromagnetic wave that propagates at very high speed outside the surface of the conductor. This speed is usually a significant fraction of the speed of light, as can be deduced from Maxwell's equations, and is therefore many times faster than the drift velocity of the electrons. For example, in AC power lines, the waves of electromagnetic energy propagate through the space between the wires, moving from a source to a distant load, even though the electrons in the wires only move back and forth over a tiny distance.
The ratio of the speed of the electromagnetic wave to the speed of light in free space is called the velocity factor, and depends on the electromagnetic properties of the conductor and the insulating materials surrounding it, and on their shape and size.
The magnitudes (not the natures) of these three velocities can be illustrated by an analogy with the three similar velocities associated with gases. (See also hydraulic analogy.) | [
{
"paragraph_id": 0,
"text": "An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge carriers, which may be one of several types of particles, depending on the conductor. In electric circuits the charge carriers are often electrons moving through a wire. In semiconductors they can be electrons or holes. In an electrolyte the charge carriers are ions, while in plasma, an ionized gas, they are ions and electrons.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The SI unit of electric current is the ampere, or amp, which is the flow of electric charge across a surface at the rate of one coulomb per second. The ampere (symbol: A) is an SI base unit. Electric current is measured using a device called an ammeter.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Electric currents create magnetic fields, which are used in motors, generators, inductors, and transformers. In ordinary conductors, they cause Joule heating, which creates light in incandescent light bulbs. Time-varying currents emit electromagnetic waves, which are used in telecommunications to broadcast information.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The conventional symbol for current is I, which originates from the French phrase intensité du courant, (current intensity). Current intensity is often referred to simply as current. The I symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating Ampère's force law (1820). The notation travelled from France to Great Britain, where it became standard, although at least one journal did not change from using C to I until 1896.",
"title": "Symbol"
},
{
"paragraph_id": 4,
"text": "The conventional direction of current, also known as conventional current, is arbitrarily defined as the direction in which positive charges flow. In a conductive material, the moving charged particles that constitute the electric current are called charge carriers. In metals, which make up the wires and other conductors in most electrical circuits, the positively charged atomic nuclei of the atoms are held in a fixed position, and the negatively charged electrons are the charge carriers, free to move about in the metal. In other materials, notably the semiconductors, the charge carriers can be positive or negative, depending on the dopant used. Positive and negative charge carriers may even be present at the same time, as happens in an electrolyte in an electrochemical cell.",
"title": "Conventions"
},
{
"paragraph_id": 5,
"text": "A flow of positive charges gives the same electric current, and has the same effect in a circuit, as an equal flow of negative charges in the opposite direction. Since current can be the flow of either positive or negative charges, or both, a convention is needed for the direction of current that is independent of the type of charge carriers. Negatively charged carriers, such as the electrons (the charge carriers in metal wires and many other electronic circuit components), therefore flow in the opposite direction of conventional current flow in an electrical circuit.",
"title": "Conventions"
},
{
"paragraph_id": 6,
"text": "A current in a wire or circuit element can flow in either of two directions. When defining a variable I {\\displaystyle I} to represent the current, the direction representing positive current must be specified, usually by an arrow on the circuit schematic diagram. This is called the reference direction of the current I {\\displaystyle I} . When analyzing electrical circuits, the actual direction of current through a specific circuit element is usually unknown until the analysis is completed. Consequently, the reference directions of currents are often assigned arbitrarily. When the circuit is solved, a negative value for the current implies the actual direction of current through that circuit element is opposite that of the chosen reference direction.",
"title": "Conventions"
},
{
"paragraph_id": 7,
"text": "Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equation that describes this relationship:",
"title": "Ohm's law"
},
{
"paragraph_id": 8,
"text": "where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms. More specifically, Ohm's law states that the R in this relation is constant, independent of the current.",
"title": "Ohm's law"
},
{
"paragraph_id": 9,
"text": "",
"title": "Alternating and direct current"
},
{
"paragraph_id": 10,
"text": "In alternating current (AC) systems, the movement of electric charge periodically reverses direction. AC is the form of electric power most commonly delivered to businesses and residences. The usual waveform of an AC power circuit is a sine wave, though certain applications use alternative waveforms, such as triangular or square waves. Audio and radio signals carried on electrical wires are also examples of alternating current. An important goal in these applications is recovery of information encoded (or modulated) onto the AC signal.",
"title": "Alternating and direct current"
},
{
"paragraph_id": 11,
"text": "In contrast, direct current (DC) refers to a system in which the movement of electric charge in only one direction (sometimes called unidirectional flow). Direct current is produced by sources such as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Alternating current can also be converted to direct current through use of a rectifier. Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. An old name for direct current was galvanic current.",
"title": "Alternating and direct current"
},
{
"paragraph_id": 12,
"text": "Natural observable examples of electric current include lightning, static electric discharge, and the solar wind, the source of the polar auroras.",
"title": "Occurrences"
},
{
"paragraph_id": 13,
"text": "Man-made occurrences of electric current include the flow of conduction electrons in metal wires such as the overhead power lines that deliver electrical energy across long distances and the smaller wires within electrical and electronic equipment. Eddy currents are electric currents that occur in conductors exposed to changing magnetic fields. Similarly, electric currents occur, particularly in the surface, of conductors exposed to electromagnetic waves. When oscillating electric currents flow at the correct voltages within radio antennas, radio waves are generated.",
"title": "Occurrences"
},
{
"paragraph_id": 14,
"text": "In electronics, other forms of electric current include the flow of electrons through resistors or through the vacuum in a vacuum tube, the flow of ions inside a battery, and the flow of holes within metals and semiconductors.",
"title": "Occurrences"
},
{
"paragraph_id": 15,
"text": "A biological example of current is the flow of ions in neurons and nerves, responsible for both thought and sensory perception.",
"title": "Occurrences"
},
{
"paragraph_id": 16,
"text": "Current can be measured using an ammeter.",
"title": "Measurement"
},
{
"paragraph_id": 17,
"text": "Electric current can be directly measured with a galvanometer, but this method involves breaking the electrical circuit, which is sometimes inconvenient.",
"title": "Measurement"
},
{
"paragraph_id": 18,
"text": "Current can also be measured without breaking the circuit by detecting the magnetic field associated with the current. Devices, at the circuit level, use various techniques to measure current:",
"title": "Measurement"
},
{
"paragraph_id": 19,
"text": "Joule heating, also known as ohmic heating and resistive heating, is the process of power dissipation by which the passage of an electric current through a conductor increases the internal energy of the conductor, converting thermodynamic work into heat. The phenomenon was first studied by James Prescott Joule in 1841. Joule immersed a length of wire in a fixed mass of water and measured the temperature rise due to a known current through the wire for a 30 minute period. By varying the current and the length of the wire he deduced that the heat produced was proportional to the square of the current multiplied by the electrical resistance of the wire.",
"title": "Resistive heating"
},
{
"paragraph_id": 20,
"text": "This relationship is known as Joule's Law. The SI unit of energy was subsequently named the joule and given the symbol J. The commonly known SI unit of power, the watt (symbol: W), is equivalent to one joule per second.",
"title": "Resistive heating"
},
{
"paragraph_id": 21,
"text": "In an electromagnet a coil of wires behaves like a magnet when an electric current flows through it. When the current is switched off, the coil loses its magnetism immediately. Electric current produces a magnetic field. The magnetic field can be visualized as a pattern of circular field lines surrounding the wire that persists as long as there is current.",
"title": "Electromagnetism"
},
{
"paragraph_id": 22,
"text": "Magnetic fields can also be used to make electric currents. When a changing magnetic field is applied to a conductor, an electromotive force (EMF) is induced, which starts an electric current, when there is a suitable path.",
"title": "Electromagnetism"
},
{
"paragraph_id": 23,
"text": "When an electric current flows in a suitably shaped conductor at radio frequencies, radio waves can be generated. These travel at the speed of light and can cause electric currents in distant conductors.",
"title": "Electromagnetism"
},
{
"paragraph_id": 24,
"text": "In metallic solids, electric charge flows by means of electrons, from lower to higher electrical potential. In other media, any stream of charged objects (ions, for example) may constitute an electric current. To provide a definition of current independent of the type of charge carriers, conventional current is defined as moving in the same direction as the positive charge flow. So, in metals where the charge carriers (electrons) are negative, conventional current is in the opposite direction to the overall electron movement. In conductors where the charge carriers are positive, conventional current is in the same direction as the charge carriers.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 25,
"text": "In a vacuum, a beam of ions or electrons may be formed. In other conductive materials, the electric current is due to the flow of both positively and negatively charged particles at the same time. In still others, the current is entirely due to positive charge flow. For example, the electric currents in electrolytes are flows of positively and negatively charged ions. In a common lead-acid electrochemical cell, electric currents are composed of positive hydronium ions flowing in one direction, and negative sulfate ions flowing in the other. Electric currents in sparks or plasma are flows of electrons as well as positive and negative ions. In ice and in certain solid electrolytes, the electric current is entirely composed of flowing ions.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 26,
"text": "In a metal, some of the outer electrons in each atom are not bound to the individual molecules as they are in molecular solids, or in full bands as they are in insulating materials, but are free to move within the metal lattice. These conduction electrons can serve as charge carriers, carrying a current. Metals are particularly conductive because there are many of these free electrons. With no external electric field applied, these electrons move about randomly due to thermal energy but, on average, there is zero net current within the metal. At room temperature, the average speed of these random motions is 10 metres per second. Given a surface through which a metal wire passes, electrons move in both directions across the surface at an equal rate. As George Gamow wrote in his popular science book, One, Two, Three...Infinity (1947), \"The metallic substances differ from all other materials by the fact that the outer shells of their atoms are bound rather loosely, and often let one of their electrons go free. Thus the interior of a metal is filled up with a large number of unattached electrons that travel aimlessly around like a crowd of displaced persons. When a metal wire is subjected to electric force applied on its opposite ends, these free electrons rush in the direction of the force, thus forming what we call an electric current.\"",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 27,
"text": "When a metal wire is connected across the two terminals of a DC voltage source such as a battery, the source places an electric field across the conductor. The moment contact is made, the free electrons of the conductor are forced to drift toward the positive terminal under the influence of this field. The free electrons are therefore the charge carrier in a typical solid conductor.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 28,
"text": "For a steady flow of charge through a surface, the current I (in amperes) can be calculated with the following equation:",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 29,
"text": "where Q is the electric charge transferred through the surface over a time t. If Q and t are measured in coulombs and seconds respectively, I is in amperes.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 30,
"text": "More generally, electric current can be represented as the rate at which charge flows through a given surface as:",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 31,
"text": "Electric currents in electrolytes are flows of electrically charged particles (ions). For example, if an electric field is placed across a solution of Na and Cl (and conditions are right) the sodium ions move towards the negative electrode (cathode), while the chloride ions move towards the positive electrode (anode). Reactions take place at both electrode surfaces, neutralizing each ion.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 32,
"text": "Water-ice and certain solid electrolytes called proton conductors contain positive hydrogen ions (\"protons\") that are mobile. In these materials, electric currents are composed of moving protons, as opposed to the moving electrons in metals.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 33,
"text": "In certain electrolyte mixtures, brightly coloured ions are the moving electric charges. The slow progress of the colour makes the current visible.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 34,
"text": "In air and other ordinary gases below the breakdown field, the dominant source of electrical conduction is via relatively few mobile ions produced by radioactive gases, ultraviolet light, or cosmic rays. Since the electrical conductivity is low, gases are dielectrics or insulators. However, once the applied electric field approaches the breakdown value, free electrons become sufficiently accelerated by the electric field to create additional free electrons by colliding, and ionizing, neutral gas atoms or molecules in a process called avalanche breakdown. The breakdown process forms a plasma that contains enough mobile electrons and positive ions to make it an electrical conductor. In the process, it forms a light emitting conductive path, such as a spark, arc or lightning.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 35,
"text": "Plasma is the state of matter where some of the electrons in a gas are stripped or \"ionized\" from their molecules or atoms. A plasma can be formed by high temperature, or by application of a high electric or alternating magnetic field as noted above. Due to their lower mass, the electrons in a plasma accelerate more quickly in response to an electric field than the heavier positive ions, and hence carry the bulk of the current. The free ions recombine to create new chemical compounds (for example, breaking atmospheric oxygen into single oxygen [O2 → 2O], which then recombine creating ozone [O3]).",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 36,
"text": "Since a \"perfect vacuum\" contains no charged particles, it normally behaves as a perfect insulator. However, metal electrode surfaces can cause a region of the vacuum to become conductive by injecting free electrons or ions through either field electron emission or thermionic emission. Thermionic emission occurs when the thermal energy exceeds the metal's work function, while field electron emission occurs when the electric field at the surface of the metal is high enough to cause tunneling, which results in the ejection of free electrons from the metal into the vacuum. Externally heated electrodes are often used to generate an electron cloud as in the filament or indirectly heated cathode of vacuum tubes. Cold electrodes can also spontaneously produce electron clouds via thermionic emission when small incandescent regions (called cathode spots or anode spots) are formed. These are incandescent regions of the electrode surface that are created by a localized high current. These regions may be initiated by field electron emission, but are then sustained by localized thermionic emission once a vacuum arc forms. These small electron-emitting regions can form quite rapidly, even explosively, on a metal surface subjected to a high electrical field. Vacuum tubes and sprytrons are some of the electronic switching and amplifying devices based on vacuum conductivity.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 37,
"text": "Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 38,
"text": "In a semiconductor it is sometimes useful to think of the current as due to the flow of positive \"holes\" (the mobile positive charge carriers that are places where the semiconductor crystal is missing a valence electron). This is the case in a p-type semiconductor. A semiconductor has electrical conductivity intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 10 to 10 siemens per centimeter (S⋅cm).",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 39,
"text": "In the classic crystalline semiconductors, electrons can have energies only within certain bands (i.e. ranges of levels of energy). Energetically, these bands are located between the energy of the ground state, the state in which electrons are tightly bound to the atomic nuclei of the material, and the free electron energy, the latter describing the energy required for an electron to escape entirely from the material. The energy bands each correspond to many discrete quantum states of the electrons, and most of the states with low energy (closer to the nucleus) are occupied, up to a particular band called the valence band. Semiconductors and insulators are distinguished from metals because the valence band in any given metal is nearly filled with electrons under usual operating conditions, while very few (semiconductor) or virtually none (insulator) of them are available in the conduction band, the band immediately above the valence band.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 40,
"text": "The ease of exciting electrons in the semiconductor from the valence band to the conduction band depends on the band gap between the bands. The size of this energy band gap serves as an arbitrary dividing line (roughly 4 eV) between semiconductors and insulators.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 41,
"text": "With covalent bonds, an electron moves by hopping to a neighboring bond. The Pauli exclusion principle requires that the electron be lifted into the higher anti-bonding state of that bond. For delocalized states, for example in one dimension – that is in a nanowire, for every energy there is a state with electrons flowing in one direction and another state with the electrons flowing in the other. For a net current to flow, more states for one direction than for the other direction must be occupied. For this to occur, energy is required, as in the semiconductor the next higher states lie above the band gap. Often this is stated as: full bands do not contribute to the electrical conductivity. However, as a semiconductor's temperature rises above absolute zero, there is more energy in the semiconductor to spend on lattice vibration and on exciting electrons into the conduction band. The current-carrying electrons in the conduction band are known as free electrons, though they are often simply called electrons if that is clear in context.",
"title": "Conduction mechanisms in various media"
},
{
"paragraph_id": 42,
"text": "Current density is the rate at which charge passes through a chosen unit area. It is defined as a vector whose magnitude is the current per unit cross-sectional area. As discussed in Reference direction, the direction is arbitrary. Conventionally, if the moving charges are positive, then the current density has the same sign as the velocity of the charges. For negative charges, the sign of the current density is opposite to the velocity of the charges. In SI units, current density (symbol: j) is expressed in the SI base units of amperes per square metre.",
"title": "Current density and Ohm's law"
},
{
"paragraph_id": 43,
"text": "In linear materials such as metals, and under low frequencies, the current density across the conductor surface is uniform. In such conditions, Ohm's law states that the current is directly proportional to the potential difference between two ends (across) of that metal (ideal) resistor (or other ohmic device):",
"title": "Current density and Ohm's law"
},
{
"paragraph_id": 44,
"text": "where I {\\displaystyle I} is the current, measured in amperes; V {\\displaystyle V} is the potential difference, measured in volts; and R {\\displaystyle R} is the resistance, measured in ohms. For alternating currents, especially at higher frequencies, skin effect causes the current to spread unevenly across the conductor cross-section, with higher density near the surface, thus increasing the apparent resistance.",
"title": "Current density and Ohm's law"
},
{
"paragraph_id": 45,
"text": "The mobile charged particles within a conductor move constantly in random directions, like the particles of a gas. (More accurately, a Fermi gas.) To create a net flow of charge, the particles must also move together with an average drift rate. Electrons are the charge carriers in most metals and they follow an erratic path, bouncing from atom to atom, but generally drifting in the opposite direction of the electric field. The speed they drift at can be calculated from the equation:",
"title": "Drift speed"
},
{
"paragraph_id": 46,
"text": "where",
"title": "Drift speed"
},
{
"paragraph_id": 47,
"text": "Typically, electric charges in solids flow slowly. For example, in a copper wire of cross-section 0.5 mm, carrying a current of 5 A, the drift velocity of the electrons is on the order of a millimetre per second. To take a different example, in the near-vacuum inside a cathode-ray tube, the electrons travel in near-straight lines at about a tenth of the speed of light.",
"title": "Drift speed"
},
{
"paragraph_id": 48,
"text": "Any accelerating electric charge, and therefore any changing electric current, gives rise to an electromagnetic wave that propagates at very high speed outside the surface of the conductor. This speed is usually a significant fraction of the speed of light, as can be deduced from Maxwell's equations, and is therefore many times faster than the drift velocity of the electrons. For example, in AC power lines, the waves of electromagnetic energy propagate through the space between the wires, moving from a source to a distant load, even though the electrons in the wires only move back and forth over a tiny distance.",
"title": "Drift speed"
},
{
"paragraph_id": 49,
"text": "The ratio of the speed of the electromagnetic wave to the speed of light in free space is called the velocity factor, and depends on the electromagnetic properties of the conductor and the insulating materials surrounding it, and on their shape and size.",
"title": "Drift speed"
},
{
"paragraph_id": 50,
"text": "The magnitudes (not the natures) of these three velocities can be illustrated by an analogy with the three similar velocities associated with gases. (See also hydraulic analogy.)",
"title": "Drift speed"
}
] | An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge carriers, which may be one of several types of particles, depending on the conductor. In electric circuits the charge carriers are often electrons moving through a wire. In semiconductors they can be electrons or holes. In an electrolyte the charge carriers are ions, while in plasma, an ionized gas, they are ions and electrons. The SI unit of electric current is the ampere, or amp, which is the flow of electric charge across a surface at the rate of one coulomb per second. The ampere is an SI base unit. Electric current is measured using a device called an ammeter. Electric currents create magnetic fields, which are used in motors, generators, inductors, and transformers. In ordinary conductors, they cause Joule heating, which creates light in incandescent light bulbs. Time-varying currents emit electromagnetic waves, which are used in telecommunications to broadcast information. | 2001-09-16T16:46:11Z | 2023-10-28T00:47:46Z | [
"Template:Math",
"Template:See also",
"Template:Snd",
"Template:Wiktionary",
"Template:Short description",
"Template:Authority control",
"Template:Main",
"Template:Further",
"Template:Cite book",
"Template:Cite web",
"Template:SI base quantities",
"Template:Rp",
"Template:Em",
"Template:Efn",
"Template:Portal",
"Template:Div col end",
"Template:Slink",
"Template:SIbrochure9th",
"Template:Lang",
"Template:Notelist",
"Template:Pp-vandalism",
"Template:Electromagnetism",
"Template:Anchor",
"Template:Cite news",
"Template:Infobox physical quantity",
"Template:Clear",
"Template:Div col",
"Template:Reflist"
] | https://en.wikipedia.org/wiki/Electric_current |
6,208 | Charles Ancillon | Charles Ancillon (28 July 1659 – 5 July 1715) was a French jurist and diplomat.
Ancillon was born in Metz into a distinguished family of Huguenots. His father, David Ancillon (1617–1692), was obliged to leave France on the revocation of the Edict of Nantes, and became pastor of the French Protestant community in Berlin.
Ancillon studied law at Marburg, Geneva and Paris, where he was called to the bar. At the request of the Huguenots at Metz, he pleaded its cause at the court of King Louis XIV, urging that it should be excepted in the revocation of the Edict of Nantes, but his efforts were unsuccessful, and he joined his father in Berlin. He was at once appointed by Elector Frederick III "juge et directeur de colonie de Berlin." He also became the first headmaster of Französisches Gymnasium Berlin. Before this, he had published several works on the revocation of the Edict of Nantes and its consequences, but his literary capacity was mediocre, his style stiff and cold, and it was his personal character rather than his reputation as a writer that earned him the confidence of the elector.
In 1687 Ancillon was appointed head of the so-called Academie des nobles, the principal educational establishment of the state; later on, as councillor of embassy, he took part in the negotiations which led to the assumption of the title of "King in Prussia" by the elector. In 1699 he succeeded Samuel Pufendorf as historiographer to the elector, and the same year replaced his uncle Joseph Ancillon as judge of all the French refugees in the Margraviate of Brandenburg.
Ancillon is mainly remembered for what he did for education in Brandenburg-Prussia, and the share he took, in co-operation with Gottfried Leibniz, in founding the Academy of Berlin. Of his fairly numerous works the one of the most value is the "Histoire de l'etablissement des Francais refugies dans les etats de Brandebourg" published in Berlin in 1690. | [
{
"paragraph_id": 0,
"text": "Charles Ancillon (28 July 1659 – 5 July 1715) was a French jurist and diplomat.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Ancillon was born in Metz into a distinguished family of Huguenots. His father, David Ancillon (1617–1692), was obliged to leave France on the revocation of the Edict of Nantes, and became pastor of the French Protestant community in Berlin.",
"title": "Life"
},
{
"paragraph_id": 2,
"text": "Ancillon studied law at Marburg, Geneva and Paris, where he was called to the bar. At the request of the Huguenots at Metz, he pleaded its cause at the court of King Louis XIV, urging that it should be excepted in the revocation of the Edict of Nantes, but his efforts were unsuccessful, and he joined his father in Berlin. He was at once appointed by Elector Frederick III \"juge et directeur de colonie de Berlin.\" He also became the first headmaster of Französisches Gymnasium Berlin. Before this, he had published several works on the revocation of the Edict of Nantes and its consequences, but his literary capacity was mediocre, his style stiff and cold, and it was his personal character rather than his reputation as a writer that earned him the confidence of the elector.",
"title": "Life"
},
{
"paragraph_id": 3,
"text": "In 1687 Ancillon was appointed head of the so-called Academie des nobles, the principal educational establishment of the state; later on, as councillor of embassy, he took part in the negotiations which led to the assumption of the title of \"King in Prussia\" by the elector. In 1699 he succeeded Samuel Pufendorf as historiographer to the elector, and the same year replaced his uncle Joseph Ancillon as judge of all the French refugees in the Margraviate of Brandenburg.",
"title": "Life"
},
{
"paragraph_id": 4,
"text": "Ancillon is mainly remembered for what he did for education in Brandenburg-Prussia, and the share he took, in co-operation with Gottfried Leibniz, in founding the Academy of Berlin. Of his fairly numerous works the one of the most value is the \"Histoire de l'etablissement des Francais refugies dans les etats de Brandebourg\" published in Berlin in 1690.",
"title": "Life"
},
{
"paragraph_id": 5,
"text": "",
"title": "External links"
}
] | Charles Ancillon was a French jurist and diplomat. | 2001-08-26T05:36:27Z | 2023-09-23T03:33:06Z | [
"Template:Reflist",
"Template:EB1911",
"Template:Internet Archive author",
"Template:Use dmy dates",
"Template:EB1911 article with no significant updates",
"Template:Snd",
"Template:Infobox person",
"Template:Gutenberg author",
"Template:Authority control",
"Template:Short description"
] | https://en.wikipedia.org/wiki/Charles_Ancillon |
6,210 | Clark Ashton Smith | Clark Ashton Smith (January 13, 1893 – August 14, 1961) was an American writer and artist. He achieved early local recognition, largely through the enthusiasm of George Sterling, for traditional verse in the vein of Swinburne. As a poet, Smith is grouped with the West Coast Romantics alongside Joaquin Miller, Sterling, and Nora May French and remembered as "The Last of the Great Romantics" and "The Bard of Auburn". Smith's work was praised by his contemporaries. H. P. Lovecraft stated that "in sheer daemonic strangeness and fertility of conception, Clark Ashton Smith is perhaps unexcelled", and Ray Bradbury said that Smith "filled my mind with incredible worlds, impossibly beautiful cities, and still more fantastic creatures".
Smith was one of "the big three of Weird Tales, with Robert E. Howard and H. P. Lovecraft", though some readers objected to his morbidness and violation of pulp traditions. The fantasy writer and critic L. Sprague de Camp said of him that "nobody since Poe has so loved a well-rotted corpse". Smith was a member of the Lovecraft circle, and his literary friendship with Lovecraft lasted from 1922 until Lovecraft's death in 1937. His work is marked by an extraordinarily rich and ornate vocabulary, a cosmic perspective and a vein of sardonic and sometimes ribald humor.
Of his writing style, Smith stated: "My own conscious ideal has been to delude the reader into accepting an impossibility, or series of impossibilities, by means of a sort of verbal black magic, in the achievement of which I make use of prose-rhythm, metaphor, simile, tone-color, counter-point, and other stylistic resources, like a sort of incantation."
Smith was born January 13, 1893, in Long Valley, Placer County, California, into a family of English and New England heritage. He spent most of his life in the small town of Auburn, California, living in a cabin built by his parents, Fanny and Timeus Smith. Smith professed to hate the town's provincialism but rarely left it until he married late in life.
His formal education was limited: he suffered from psychological disorders including intense agoraphobia, and although he was accepted to high school after attending eight years of grammar school, his parents decided it was better for him to be taught at home. An insatiable reader with an extraordinary eidetic memory, Smith appeared to retain most or all of whatever he read. After leaving formal education, he embarked upon a self-directed course of literature, including Robinson Crusoe, Gulliver's Travels, the fairy tales of Hans Christian Andersen and Madame d'Aulnoy, the Arabian Nights and the poems of Edgar Allan Poe. He read an unabridged dictionary word for word, studying not only the definitions of the words but also their etymology.
The other main course in Smith's self-education was to read the complete 11th edition of the Encyclopædia Britannica at least twice. Smith later taught himself French and Spanish to translate verse out of those languages, including works by Gérard de Nerval, Paul Verlaine, Amado Nervo, Gustavo Adolfo Bécquer and all but 6 of Charles Baudelaire's 157 poems in The Flowers of Evil.
His first literary efforts, at the age of 11, took the form of fairy tales and imitations of the Arabian Nights. Later, he wrote long adventure novels dealing with Oriental life. By 14 he had already written a short adventure novel called The Black Diamonds which was lost for years until published in 2002. Another juvenile novel was written in his teenaged years: The Sword of Zagan (unpublished until 2004). Like The Black Diamonds, it uses a medieval, Arabian Nights-like setting, and the Arabian Nights, like the fairy tales of the Brothers Grimm and the works of Edgar Allan Poe, are known to have strongly influenced Smith's early writing, as did William Beckford's Vathek.
At age 17, he sold several tales to The Black Cat, a magazine which specialized in unusual tales. He also published some tales in the Overland Monthly in this brief foray into fiction which preceded his poetic career.
However, it was primarily poetry that motivated the young Smith and he confined his efforts to poetry for more than a decade. In his later youth, Smith made the acquaintance of the San Francisco poet George Sterling through a member of the local Auburn Monday Night Club, where he read several of his poems with considerable success. On a month-long visit to Sterling in Carmel, California, Smith was introduced by Sterling to the poetry of Baudelaire.
He became Sterling's protégé and Sterling helped him to publish his first volume of poems, The Star-Treader and Other Poems, at the age of 19. Smith received international acclaim for the collection. The Star-Treader was received very favorably by American critics, one of whom named Smith "the Keats of the Pacific". Smith briefly moved among the circle that included Ambrose Bierce and Jack London, but his early fame soon faded away.
A little later, Smith's health broke down and for eight years his literary production was intermittent, though he produced his best poetry during this period. A small volume, Odes and Sonnets, was brought out in 1918. Smith came into contact with literary figures who would later form part of H.P. Lovecraft's circle of correspondents; Smith knew them far earlier than Lovecraft. These figures include poet Samuel Loveman and bookman George Kirk. It was Smith who in fact later introduced Donald Wandrei to Lovecraft. For this reason, it has been suggested that Lovecraft might as well be referred to as a member of a "Smith" circle as Smith was a member of a Lovecraft one.
In 1920 Smith composed a celebrated long poem in blank verse, The Hashish Eater, or The Apocalypse of Evil which was published in Ebony and Crystal (1922). This was followed by a fan letter from H. P. Lovecraft, which was the beginning of 15 years of friendship and correspondence. With studied playfulness, Smith and Lovecraft borrowed each other's coinages of place names and the names of strange gods for their stories, though so different is Smith's treatment of the Lovecraft theme that it has been dubbed the "Clark Ashton Smythos."
In 1925 Smith published Sandalwood, which was partly funded by a gift of $50 from Donald Wandrei. He wrote little fiction in this period with the exception of some imaginative vignettes or prose poems. Smith was poor for most of his life and often did hard manual jobs such as fruit picking and woodcutting to support himself and his parents. He was an able cook and made many kinds of wine. He also did well digging, typing and journalism, as well as contributing a column to The Auburn Journal and sometimes worked as its night editor.
One of Smith's artistic patrons and frequent correspondents was San Francisco businessman Albert M. Bender.
At the beginning of the Depression in 1929, with his aged parents' health weakening, Smith resumed fiction writing and turned out more than a hundred short stories between 1929 and 1934, nearly all of which can be classed as weird horror or science fiction. Like Lovecraft, he drew upon the nightmares that had plagued him during youthful spells of sickness. Brian Stableford has written that the stories written during this brief phase of hectic productivity "constitute one of the most remarkable oeuvres in imaginative literature".
He published at his own expense a volume containing six of his best stories, The Double Shadow and Other Fantasies, in an edition of 1000 copies printed by the Auburn Journal. The theme of much of his work is egotism and its supernatural punishment; his weird fiction is generally macabre in subject matter, gloatingly preoccupied with images of death, decay and abnormality.
Most of Smith's weird fiction falls into four series set variously in Hyperborea, Poseidonis, Averoigne and Zothique. Hyperborea, which is a lost continent of the Miocene period, and Poseidonis, which is a remnant of Atlantis, are much the same, with a magical culture characterized by bizarreness, cruelty, death and postmortem horrors. Averoigne is Smith's version of pre-modern France, comparable to James Branch Cabell's Poictesme. Zothique exists millions of years in the future. It is "the last continent of earth, when the sun is dim and tarnished". These tales have been compared to the Dying Earth sequence of Jack Vance.
In 1933 Smith began corresponding with Robert E. Howard, the Texan creator of Conan the Barbarian. From 1933 to 1936, Smith, Howard and Lovecraft were the leaders of the Weird Tales school of fiction and corresponded frequently, although they never met. The writer of oriental fantasies E. Hoffmann Price is the only man known to have met all three in the flesh.
Critic Steve Behrends has suggested that the frequent theme of 'loss' in Smith's fiction (many of his characters attempt to recapture a long-vanished youth, early love, or picturesque past) may reflect Smith's own feeling that his career had suffered a "fall from grace":
Smith's late teens and early twenties had certainly been a heady period: he'd been taken under the wing of a personal idol, the poet George Sterling, and his first book of poetry had brought him comparisons to Keats and Shelley. This notoriety must surely have raised his standing in his small hometown. And yet the depression found Smith without a job or viable occupation, unable to eke out a living as a poet, with girlfriends berating him for his lack of ambition. And while his turn to writing fiction did put bread on the table, he found it a very distasteful business at times—he had once said to Sterling that writing prose was "a hateful task, for a poet, and [one which] wouldn't be necessary in any true civilisation." In short, it may be that Smith experienced that variety of "let-down" or loss peculiar to the child prodigies.
In September 1935, Smith's mother Fanny died. Smith spent the next two years nursing his father through his last illness. Timeus died in December 1937. Aged 44, Smith now virtually ceased writing fiction. He had been severely affected by several tragedies occurring in a short period of time: Robert E. Howard's death by suicide (1936), Lovecraft's death from cancer (1937) and the deaths of his parents, which left him exhausted. As a result, he withdrew from the scene, marking the end of Weird Tales's Golden Age. He began sculpting and resumed the writing of poetry. However, Smith was visited by many writers at his cabin, including Fritz Leiber, Rah Hoffman, Francis T. Laney and others.
In 1942, three years after August Derleth founded Arkham House for the purpose of preserving the work of H.P. Lovecraft, Derleth published the first of several major collections of Smith's fiction, Out of Space and Time (1942). This was followed by Lost Worlds (1944). The books sold slowly, went out of print and became costly rarities. Derleth published five more volumes of Smith's prose and two of his verse, and at his death in 1971 had a large volume of Smith's poems in press.
In 1953, Smith suffered a coronary attack. Aged 61, he married Carol(yn) Jones Dorman on November 10, 1954. Dorman had much experience in Hollywood and radio public relations. After honeymooning at the Smith cabin, they moved to Pacific Grove, California, where he set up a household including her three children from a previous marriage. For several years he alternated between the house on Indian Ridge and their house in Pacific Grove. Smith having sold most of his father's tract, in 1957 the old house burned – the Smiths believed by arson, others said by accident.
Smith now reluctantly did gardening for other residents at Pacific Grove, and grew a goatee. He spent much time shopping and walking near the seafront but despite Derleth's badgering, resisted the writing of more fiction. In 1961 he suffered a series of strokes and in August 1961 he quietly died in his sleep, aged 68. After Smith's death, Carol remarried (becoming Carolyn Wakefield) and subsequently died of cancer.
The poet's ashes were buried beside, or beneath, a boulder to the immediate west of where his childhood home (destroyed by fire in 1957) stood; some were also scattered in a stand of blue oaks near the boulder. There was no marker. Plaques recognizing Smith have been erected at the Auburn Placer County Library in 1985 and in Bicentennial Park in Auburn in 2003.
Bookseller Roy A. Squires was appointed Smith's "west coast executor", with Jack L. Chalker as his "east coast executor". Squires published many letterpress editions of individual Smith poems.
Smith's literary estate is represented by his stepson, Prof William Dorman, director of CASiana Literary Enterprises. Arkham House owns the copyright to many Smith stories, though some are now in the public domain.
For 'posthumous collaborations' of Smith (stories completed by Lin Carter), see the entry on Lin Carter.
While Smith was always an artist who worked in several very different media, it is possible to identify three distinct periods in which one form of art had precedence over the others.
Smith published most of his volumes of poetry in this period, including the aforementioned The Star-Treader and Other Poems, as well as Odes and Sonnets (1918), Ebony and Crystal (1922) and Sandalwood (1925). His long poem The Hashish-Eater; Or, the Apocalypse of Evil was written in 1920.
Smith wrote most of his weird fiction and Cthulhu Mythos stories, inspired by H. P. Lovecraft. Creatures of his invention include Aforgomon, Rlim-Shaikorth, Mordiggian, Tsathoggua, the wizard Eibon, and various others. In an homage to his friend, Lovecraft referred in "The Whisperer in Darkness" and "The Battle That Ended the Century" (written in collaboration with R. H. Barlow) to an Atlantean high-priest, "Klarkash-Ton".
Smith's weird stories form several cycles, called after the lands in which they are set: Averoigne, Hyperborea, Mars, Poseidonis, Zothique. To some extent Smith was influenced in his vision of such lost worlds by the teachings of Theosophy and the writings of Helena Blavatsky. Stories set in Zothique belong to the Dying Earth subgenre. Amongst Smith's science fiction tales are stories set on Mars and the invented planet of Xiccarph.
His short stories originally appeared in the magazines Weird Tales, Strange Tales, Astounding Stories, Stirring Science Stories and Wonder Stories.
Clark Ashton Smith was the third member of the great triumvirate of Weird Tales, with Lovecraft and Robert E. Howard.
Many of Smith's stories were published in six hardcover volumes by August Derleth under his Arkham House imprint. For a full bibliography to 1978, see Sidney-Fryer, Emperor of Dreams (cited below). S.T. Joshi is working with other scholars to produce an updated bibliography of Smith's work.
A selection of Smith's best-known tales includes:
By this time his interest in writing fiction began to lessen and he turned to creating sculptures from soft rock such as soapstone. Smith also made hundreds of fantastic paintings and drawings.
The authoritative bibliography on Smith's work is S. T. Joshi, David E. Schultz, and Scott Conners' Clark Ashton Smith: A Comprehensive Bibliography. NY: Hippocampus Press, 2020. The first Smith bibliography, which focused on his short fiction, was The Tales Of Clark Ashton Smith, published by Thomas G L Cockcroft in New Zealand in 1951.
Scholars S.T. Joshi and David E. Schultz are preparing various additional volumes of Smith's letters to such of his individual correspondents as Donald Wandrei and Robert H. Barlow. | [
{
"paragraph_id": 0,
"text": "Clark Ashton Smith (January 13, 1893 – August 14, 1961) was an American writer and artist. He achieved early local recognition, largely through the enthusiasm of George Sterling, for traditional verse in the vein of Swinburne. As a poet, Smith is grouped with the West Coast Romantics alongside Joaquin Miller, Sterling, and Nora May French and remembered as \"The Last of the Great Romantics\" and \"The Bard of Auburn\". Smith's work was praised by his contemporaries. H. P. Lovecraft stated that \"in sheer daemonic strangeness and fertility of conception, Clark Ashton Smith is perhaps unexcelled\", and Ray Bradbury said that Smith \"filled my mind with incredible worlds, impossibly beautiful cities, and still more fantastic creatures\".",
"title": ""
},
{
"paragraph_id": 1,
"text": "Smith was one of \"the big three of Weird Tales, with Robert E. Howard and H. P. Lovecraft\", though some readers objected to his morbidness and violation of pulp traditions. The fantasy writer and critic L. Sprague de Camp said of him that \"nobody since Poe has so loved a well-rotted corpse\". Smith was a member of the Lovecraft circle, and his literary friendship with Lovecraft lasted from 1922 until Lovecraft's death in 1937. His work is marked by an extraordinarily rich and ornate vocabulary, a cosmic perspective and a vein of sardonic and sometimes ribald humor.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Of his writing style, Smith stated: \"My own conscious ideal has been to delude the reader into accepting an impossibility, or series of impossibilities, by means of a sort of verbal black magic, in the achievement of which I make use of prose-rhythm, metaphor, simile, tone-color, counter-point, and other stylistic resources, like a sort of incantation.\"",
"title": ""
},
{
"paragraph_id": 3,
"text": "Smith was born January 13, 1893, in Long Valley, Placer County, California, into a family of English and New England heritage. He spent most of his life in the small town of Auburn, California, living in a cabin built by his parents, Fanny and Timeus Smith. Smith professed to hate the town's provincialism but rarely left it until he married late in life.",
"title": "Biography"
},
{
"paragraph_id": 4,
"text": "His formal education was limited: he suffered from psychological disorders including intense agoraphobia, and although he was accepted to high school after attending eight years of grammar school, his parents decided it was better for him to be taught at home. An insatiable reader with an extraordinary eidetic memory, Smith appeared to retain most or all of whatever he read. After leaving formal education, he embarked upon a self-directed course of literature, including Robinson Crusoe, Gulliver's Travels, the fairy tales of Hans Christian Andersen and Madame d'Aulnoy, the Arabian Nights and the poems of Edgar Allan Poe. He read an unabridged dictionary word for word, studying not only the definitions of the words but also their etymology.",
"title": "Biography"
},
{
"paragraph_id": 5,
"text": "The other main course in Smith's self-education was to read the complete 11th edition of the Encyclopædia Britannica at least twice. Smith later taught himself French and Spanish to translate verse out of those languages, including works by Gérard de Nerval, Paul Verlaine, Amado Nervo, Gustavo Adolfo Bécquer and all but 6 of Charles Baudelaire's 157 poems in The Flowers of Evil.",
"title": "Biography"
},
{
"paragraph_id": 6,
"text": "His first literary efforts, at the age of 11, took the form of fairy tales and imitations of the Arabian Nights. Later, he wrote long adventure novels dealing with Oriental life. By 14 he had already written a short adventure novel called The Black Diamonds which was lost for years until published in 2002. Another juvenile novel was written in his teenaged years: The Sword of Zagan (unpublished until 2004). Like The Black Diamonds, it uses a medieval, Arabian Nights-like setting, and the Arabian Nights, like the fairy tales of the Brothers Grimm and the works of Edgar Allan Poe, are known to have strongly influenced Smith's early writing, as did William Beckford's Vathek.",
"title": "Biography"
},
{
"paragraph_id": 7,
"text": "At age 17, he sold several tales to The Black Cat, a magazine which specialized in unusual tales. He also published some tales in the Overland Monthly in this brief foray into fiction which preceded his poetic career.",
"title": "Biography"
},
{
"paragraph_id": 8,
"text": "However, it was primarily poetry that motivated the young Smith and he confined his efforts to poetry for more than a decade. In his later youth, Smith made the acquaintance of the San Francisco poet George Sterling through a member of the local Auburn Monday Night Club, where he read several of his poems with considerable success. On a month-long visit to Sterling in Carmel, California, Smith was introduced by Sterling to the poetry of Baudelaire.",
"title": "Biography"
},
{
"paragraph_id": 9,
"text": "He became Sterling's protégé and Sterling helped him to publish his first volume of poems, The Star-Treader and Other Poems, at the age of 19. Smith received international acclaim for the collection. The Star-Treader was received very favorably by American critics, one of whom named Smith \"the Keats of the Pacific\". Smith briefly moved among the circle that included Ambrose Bierce and Jack London, but his early fame soon faded away.",
"title": "Biography"
},
{
"paragraph_id": 10,
"text": "A little later, Smith's health broke down and for eight years his literary production was intermittent, though he produced his best poetry during this period. A small volume, Odes and Sonnets, was brought out in 1918. Smith came into contact with literary figures who would later form part of H.P. Lovecraft's circle of correspondents; Smith knew them far earlier than Lovecraft. These figures include poet Samuel Loveman and bookman George Kirk. It was Smith who in fact later introduced Donald Wandrei to Lovecraft. For this reason, it has been suggested that Lovecraft might as well be referred to as a member of a \"Smith\" circle as Smith was a member of a Lovecraft one.",
"title": "Biography"
},
{
"paragraph_id": 11,
"text": "In 1920 Smith composed a celebrated long poem in blank verse, The Hashish Eater, or The Apocalypse of Evil which was published in Ebony and Crystal (1922). This was followed by a fan letter from H. P. Lovecraft, which was the beginning of 15 years of friendship and correspondence. With studied playfulness, Smith and Lovecraft borrowed each other's coinages of place names and the names of strange gods for their stories, though so different is Smith's treatment of the Lovecraft theme that it has been dubbed the \"Clark Ashton Smythos.\"",
"title": "Biography"
},
{
"paragraph_id": 12,
"text": "In 1925 Smith published Sandalwood, which was partly funded by a gift of $50 from Donald Wandrei. He wrote little fiction in this period with the exception of some imaginative vignettes or prose poems. Smith was poor for most of his life and often did hard manual jobs such as fruit picking and woodcutting to support himself and his parents. He was an able cook and made many kinds of wine. He also did well digging, typing and journalism, as well as contributing a column to The Auburn Journal and sometimes worked as its night editor.",
"title": "Biography"
},
{
"paragraph_id": 13,
"text": "One of Smith's artistic patrons and frequent correspondents was San Francisco businessman Albert M. Bender.",
"title": "Biography"
},
{
"paragraph_id": 14,
"text": "At the beginning of the Depression in 1929, with his aged parents' health weakening, Smith resumed fiction writing and turned out more than a hundred short stories between 1929 and 1934, nearly all of which can be classed as weird horror or science fiction. Like Lovecraft, he drew upon the nightmares that had plagued him during youthful spells of sickness. Brian Stableford has written that the stories written during this brief phase of hectic productivity \"constitute one of the most remarkable oeuvres in imaginative literature\".",
"title": "Biography"
},
{
"paragraph_id": 15,
"text": "He published at his own expense a volume containing six of his best stories, The Double Shadow and Other Fantasies, in an edition of 1000 copies printed by the Auburn Journal. The theme of much of his work is egotism and its supernatural punishment; his weird fiction is generally macabre in subject matter, gloatingly preoccupied with images of death, decay and abnormality.",
"title": "Biography"
},
{
"paragraph_id": 16,
"text": "Most of Smith's weird fiction falls into four series set variously in Hyperborea, Poseidonis, Averoigne and Zothique. Hyperborea, which is a lost continent of the Miocene period, and Poseidonis, which is a remnant of Atlantis, are much the same, with a magical culture characterized by bizarreness, cruelty, death and postmortem horrors. Averoigne is Smith's version of pre-modern France, comparable to James Branch Cabell's Poictesme. Zothique exists millions of years in the future. It is \"the last continent of earth, when the sun is dim and tarnished\". These tales have been compared to the Dying Earth sequence of Jack Vance.",
"title": "Biography"
},
{
"paragraph_id": 17,
"text": "In 1933 Smith began corresponding with Robert E. Howard, the Texan creator of Conan the Barbarian. From 1933 to 1936, Smith, Howard and Lovecraft were the leaders of the Weird Tales school of fiction and corresponded frequently, although they never met. The writer of oriental fantasies E. Hoffmann Price is the only man known to have met all three in the flesh.",
"title": "Biography"
},
{
"paragraph_id": 18,
"text": "Critic Steve Behrends has suggested that the frequent theme of 'loss' in Smith's fiction (many of his characters attempt to recapture a long-vanished youth, early love, or picturesque past) may reflect Smith's own feeling that his career had suffered a \"fall from grace\":",
"title": "Biography"
},
{
"paragraph_id": 19,
"text": "Smith's late teens and early twenties had certainly been a heady period: he'd been taken under the wing of a personal idol, the poet George Sterling, and his first book of poetry had brought him comparisons to Keats and Shelley. This notoriety must surely have raised his standing in his small hometown. And yet the depression found Smith without a job or viable occupation, unable to eke out a living as a poet, with girlfriends berating him for his lack of ambition. And while his turn to writing fiction did put bread on the table, he found it a very distasteful business at times—he had once said to Sterling that writing prose was \"a hateful task, for a poet, and [one which] wouldn't be necessary in any true civilisation.\" In short, it may be that Smith experienced that variety of \"let-down\" or loss peculiar to the child prodigies.",
"title": "Biography"
},
{
"paragraph_id": 20,
"text": "In September 1935, Smith's mother Fanny died. Smith spent the next two years nursing his father through his last illness. Timeus died in December 1937. Aged 44, Smith now virtually ceased writing fiction. He had been severely affected by several tragedies occurring in a short period of time: Robert E. Howard's death by suicide (1936), Lovecraft's death from cancer (1937) and the deaths of his parents, which left him exhausted. As a result, he withdrew from the scene, marking the end of Weird Tales's Golden Age. He began sculpting and resumed the writing of poetry. However, Smith was visited by many writers at his cabin, including Fritz Leiber, Rah Hoffman, Francis T. Laney and others.",
"title": "Biography"
},
{
"paragraph_id": 21,
"text": "In 1942, three years after August Derleth founded Arkham House for the purpose of preserving the work of H.P. Lovecraft, Derleth published the first of several major collections of Smith's fiction, Out of Space and Time (1942). This was followed by Lost Worlds (1944). The books sold slowly, went out of print and became costly rarities. Derleth published five more volumes of Smith's prose and two of his verse, and at his death in 1971 had a large volume of Smith's poems in press.",
"title": "Biography"
},
{
"paragraph_id": 22,
"text": "In 1953, Smith suffered a coronary attack. Aged 61, he married Carol(yn) Jones Dorman on November 10, 1954. Dorman had much experience in Hollywood and radio public relations. After honeymooning at the Smith cabin, they moved to Pacific Grove, California, where he set up a household including her three children from a previous marriage. For several years he alternated between the house on Indian Ridge and their house in Pacific Grove. Smith having sold most of his father's tract, in 1957 the old house burned – the Smiths believed by arson, others said by accident.",
"title": "Biography"
},
{
"paragraph_id": 23,
"text": "Smith now reluctantly did gardening for other residents at Pacific Grove, and grew a goatee. He spent much time shopping and walking near the seafront but despite Derleth's badgering, resisted the writing of more fiction. In 1961 he suffered a series of strokes and in August 1961 he quietly died in his sleep, aged 68. After Smith's death, Carol remarried (becoming Carolyn Wakefield) and subsequently died of cancer.",
"title": "Biography"
},
{
"paragraph_id": 24,
"text": "The poet's ashes were buried beside, or beneath, a boulder to the immediate west of where his childhood home (destroyed by fire in 1957) stood; some were also scattered in a stand of blue oaks near the boulder. There was no marker. Plaques recognizing Smith have been erected at the Auburn Placer County Library in 1985 and in Bicentennial Park in Auburn in 2003.",
"title": "Biography"
},
{
"paragraph_id": 25,
"text": "Bookseller Roy A. Squires was appointed Smith's \"west coast executor\", with Jack L. Chalker as his \"east coast executor\". Squires published many letterpress editions of individual Smith poems.",
"title": "Biography"
},
{
"paragraph_id": 26,
"text": "Smith's literary estate is represented by his stepson, Prof William Dorman, director of CASiana Literary Enterprises. Arkham House owns the copyright to many Smith stories, though some are now in the public domain.",
"title": "Biography"
},
{
"paragraph_id": 27,
"text": "For 'posthumous collaborations' of Smith (stories completed by Lin Carter), see the entry on Lin Carter.",
"title": "Biography"
},
{
"paragraph_id": 28,
"text": "While Smith was always an artist who worked in several very different media, it is possible to identify three distinct periods in which one form of art had precedence over the others.",
"title": "Artistic periods"
},
{
"paragraph_id": 29,
"text": "Smith published most of his volumes of poetry in this period, including the aforementioned The Star-Treader and Other Poems, as well as Odes and Sonnets (1918), Ebony and Crystal (1922) and Sandalwood (1925). His long poem The Hashish-Eater; Or, the Apocalypse of Evil was written in 1920.",
"title": "Artistic periods"
},
{
"paragraph_id": 30,
"text": "Smith wrote most of his weird fiction and Cthulhu Mythos stories, inspired by H. P. Lovecraft. Creatures of his invention include Aforgomon, Rlim-Shaikorth, Mordiggian, Tsathoggua, the wizard Eibon, and various others. In an homage to his friend, Lovecraft referred in \"The Whisperer in Darkness\" and \"The Battle That Ended the Century\" (written in collaboration with R. H. Barlow) to an Atlantean high-priest, \"Klarkash-Ton\".",
"title": "Artistic periods"
},
{
"paragraph_id": 31,
"text": "Smith's weird stories form several cycles, called after the lands in which they are set: Averoigne, Hyperborea, Mars, Poseidonis, Zothique. To some extent Smith was influenced in his vision of such lost worlds by the teachings of Theosophy and the writings of Helena Blavatsky. Stories set in Zothique belong to the Dying Earth subgenre. Amongst Smith's science fiction tales are stories set on Mars and the invented planet of Xiccarph.",
"title": "Artistic periods"
},
{
"paragraph_id": 32,
"text": "His short stories originally appeared in the magazines Weird Tales, Strange Tales, Astounding Stories, Stirring Science Stories and Wonder Stories.",
"title": "Artistic periods"
},
{
"paragraph_id": 33,
"text": "Clark Ashton Smith was the third member of the great triumvirate of Weird Tales, with Lovecraft and Robert E. Howard.",
"title": "Artistic periods"
},
{
"paragraph_id": 34,
"text": "Many of Smith's stories were published in six hardcover volumes by August Derleth under his Arkham House imprint. For a full bibliography to 1978, see Sidney-Fryer, Emperor of Dreams (cited below). S.T. Joshi is working with other scholars to produce an updated bibliography of Smith's work.",
"title": "Artistic periods"
},
{
"paragraph_id": 35,
"text": "A selection of Smith's best-known tales includes:",
"title": "Artistic periods"
},
{
"paragraph_id": 36,
"text": "By this time his interest in writing fiction began to lessen and he turned to creating sculptures from soft rock such as soapstone. Smith also made hundreds of fantastic paintings and drawings.",
"title": "Artistic periods"
},
{
"paragraph_id": 37,
"text": "The authoritative bibliography on Smith's work is S. T. Joshi, David E. Schultz, and Scott Conners' Clark Ashton Smith: A Comprehensive Bibliography. NY: Hippocampus Press, 2020. The first Smith bibliography, which focused on his short fiction, was The Tales Of Clark Ashton Smith, published by Thomas G L Cockcroft in New Zealand in 1951.",
"title": "Bibliography"
},
{
"paragraph_id": 38,
"text": "Scholars S.T. Joshi and David E. Schultz are preparing various additional volumes of Smith's letters to such of his individual correspondents as Donald Wandrei and Robert H. Barlow.",
"title": "Bibliography"
}
] | Clark Ashton Smith was an American writer and artist. He achieved early local recognition, largely through the enthusiasm of George Sterling, for traditional verse in the vein of Swinburne. As a poet, Smith is grouped with the West Coast Romantics alongside Joaquin Miller, Sterling, and Nora May French and remembered as "The Last of the Great Romantics" and "The Bard of Auburn". Smith's work was praised by his contemporaries. H. P. Lovecraft stated that "in sheer daemonic strangeness and fertility of conception, Clark Ashton Smith is perhaps unexcelled", and Ray Bradbury said that Smith "filled my mind with incredible worlds, impossibly beautiful cities, and still more fantastic creatures". Smith was one of "the big three of Weird Tales, with Robert E. Howard and H. P. Lovecraft", though some readers objected to his morbidness and violation of pulp traditions. The fantasy writer and critic L. Sprague de Camp said of him that "nobody since Poe has so loved a well-rotted corpse". Smith was a member of the Lovecraft circle, and his literary friendship with Lovecraft lasted from 1922 until Lovecraft's death in 1937. His work is marked by an extraordinarily rich and ornate vocabulary, a cosmic perspective and a vein of sardonic and sometimes ribald humor. Of his writing style, Smith stated: "My own conscious ideal has been to delude the reader into accepting an impossibility, or series of impossibilities, by means of a sort of verbal black magic, in the achievement of which I make use of prose-rhythm, metaphor, simile, tone-color, counter-point, and other stylistic resources, like a sort of incantation." | 2001-10-06T19:50:50Z | 2023-12-12T00:36:39Z | [
"Template:Reflist",
"Template:Webarchive",
"Template:Sister project links",
"Template:FadedPage",
"Template:OL author",
"Template:Other people",
"Template:Infobox writer",
"Template:ISBN",
"Template:Portal bar",
"Template:Cite book",
"Template:Cite journal",
"Template:Internet Archive author",
"Template:Works of Clark Ashton Smith",
"Template:Authority control",
"Template:Use mdy dates",
"Template:'",
"Template:See also",
"Template:Short description",
"Template:Gutenberg author",
"Template:ISFDB name",
"Template:Library resources box",
"Template:Librivox author",
"Template:Cthulhu Mythos",
"Template:Citation needed",
"Template:Blockquote",
"Template:Cite web"
] | https://en.wikipedia.org/wiki/Clark_Ashton_Smith |
6,211 | Context-sensitive grammar | A context-sensitive grammar (CSG) is a formal grammar in which the left-hand sides and right-hand sides of any production rules may be surrounded by a context of terminal and nonterminal symbols. Context-sensitive grammars are more general than context-free grammars, in the sense that there are languages that can be described by a CSG but not by a context-free grammar. Context-sensitive grammars are less general (in the same sense) than unrestricted grammars. Thus, CSGs are positioned between context-free and unrestricted grammars in the Chomsky hierarchy.
A formal language that can be described by a context-sensitive grammar, or, equivalently, by a noncontracting grammar or a linear bounded automaton, is called a context-sensitive language. Some textbooks actually define CSGs as non-contracting, although this is not how Noam Chomsky defined them in 1959. This choice of definition makes no difference in terms of the languages generated (i.e. the two definitions are weakly equivalent), but it does make a difference in terms of what grammars are structurally considered context-sensitive; the latter issue was analyzed by Chomsky in 1963.
Chomsky introduced context-sensitive grammars as a way to describe the syntax of natural language where it is often the case that a word may or may not be appropriate in a certain place depending on the context. Walter Savitch has criticized the terminology "context-sensitive" as misleading and proposed "non-erasing" as better explaining the distinction between a CSG and an unrestricted grammar.
Although it is well known that certain features of languages (e.g. cross-serial dependency) are not context-free, it is an open question how much of CSGs' expressive power is needed to capture the context sensitivity found in natural languages. Subsequent research in this area has focused on the more computationally tractable mildly context-sensitive languages. The syntaxes of some visual programming languages can be described by context-sensitive graph grammars.
Let us notate a formal grammar as G = ( N , Σ , P , S ) {\displaystyle G=(N,\Sigma ,P,S)} , with N {\displaystyle N} a set of nonterminal symbols, Σ {\displaystyle \Sigma } a set of terminal symbols, P {\displaystyle P} a set of production rules, and S ∈ N {\displaystyle S\in N} the start symbol.
A string u ∈ ( N ∪ Σ ) ∗ {\displaystyle u\in (N\cup \Sigma )^{*}} directly yields, or directly derives to, a string v ∈ ( N ∪ Σ ) ∗ {\displaystyle v\in (N\cup \Sigma )^{*}} , denoted as u ⇒ v {\displaystyle u\Rightarrow v} , if v can be obtained from u by an application of some production rule in P, that is, if u = γ L δ {\displaystyle u=\gamma L\delta } and v = γ R δ {\displaystyle v=\gamma R\delta } , where ( L → R ) ∈ P {\displaystyle (L\to R)\in P} is a production rule, and γ , δ ∈ ( N ∪ Σ ) ∗ {\displaystyle \gamma ,\delta \in (N\cup \Sigma )^{*}} is the unaffected left and right part of the string, respectively. More generally, u is said to yield, or derive to, v, denoted as u ⇒ ∗ v {\displaystyle u\Rightarrow ^{*}v} , if v can be obtained from u by repeated application of production rules, that is, if u = u 1 ⇒ . . . ⇒ u n = v {\displaystyle u=u_{1}\Rightarrow ...\Rightarrow u_{n}=v} for some n ≥ 0 and some strings u 2 , . . . , u n − 1 ∈ ( N ∪ Σ ) ∗ {\displaystyle u_{2},...,u_{n-1}\in (N\cup \Sigma )^{*}} . In other words, the relation ⇒ ∗ {\displaystyle \Rightarrow ^{*}} is the reflexive transitive closure of the relation ⇒ {\displaystyle \Rightarrow } .
The language of the grammar G is the set of all terminal-symbol strings derivable from its start symbol, formally: L ( G ) = { w ∈ Σ ∗ ∣ S ⇒ ∗ w } {\displaystyle L(G)=\{w\in \Sigma ^{*}\mid S\Rightarrow ^{*}w\}} . Derivations that do not end in a string composed of terminal symbols only are possible, but do not contribute to L(G).
A formal grammar is context-sensitive if each rule in P is either of the form S → ε {\displaystyle S\to \varepsilon } where ε {\displaystyle \varepsilon } is the empty string, or of the form
with A ∈ N, α , β ∈ ( N ∪ Σ ∖ { S } ) ∗ {\displaystyle \alpha ,\beta \in (N\cup \Sigma \setminus \{S\})^{*}} , and γ ∈ ( N ∪ Σ ∖ { S } ) + {\displaystyle \gamma \in (N\cup \Sigma \setminus \{S\})^{+}} .
The name context-sensitive is explained by the α and β that form the context of A and determine whether A can be replaced with γ or not. By contrast, in a context-free grammar, no context is present: the left hand side of every production rule is just a nonterminal.
The string γ is not allowed to be empty. Without this restriction, the resulting grammars become equal in power to unrestricted grammars.
A noncontracting grammar is a grammar in which for any production rule, of the form u → v, the length of u is less than or equal to the length of v.
Every context-sensitive grammar is noncontracting, while every noncontracting grammar can be converted into an equivalent context-sensitive grammar; the two classes are weakly equivalent.
Some authors use the term context-sensitive grammar to refer to noncontracting grammars in general.
The left-context- and right-context-sensitive grammars are defined by restricting the rules to just the form αA → αγ and to just Aβ → γβ, respectively. The languages generated by these grammars are also the full class of context-sensitive languages. The equivalence was established by Penttonen normal form.
The following context-sensitive grammar, with start symbol S, generates the canonical non-context-free language { abc | n ≥ 1 } :
Rules 1 and 2 allow for blowing-up S to aBC(BC); rules 3 to 6 allow for successively exchanging each CB to BC (four rules are needed for that since a rule CB → BC wouldn't fit into the scheme αAβ → αγβ); rules 7–10 allow replacing a non-terminals B and C with its corresponding terminals b and c respectively, provided it is in the right place. A generation chain for aaabbbccc is:
More complicated grammars can be used to parse { abcd | n ≥ 1 }, and other languages with even more letters. Here we show a simpler approach using non-contracting grammars: Start with a kernel of regular productions generating the sentential forms ( A B C D ) n a b c d {\displaystyle (ABCD)^{n}abcd} and then include the non contracting productions p D a : D a → a D {\displaystyle p_{Da}:Da\rightarrow aD} , p D b : D b → b D {\displaystyle p_{Db}:Db\rightarrow bD} , p D c : D c → c D {\displaystyle p_{Dc}:Dc\rightarrow cD} , p D d : D d → d d {\displaystyle p_{Dd}:Dd\rightarrow dd} , p C a : C a → a C {\displaystyle p_{Ca}:Ca\rightarrow aC} , p C b : C b → b C {\displaystyle p_{Cb}:Cb\rightarrow bC} , p C c : C c → c c {\displaystyle p_{Cc}:Cc\rightarrow cc} , p B a : B a → a B {\displaystyle p_{Ba}:Ba\rightarrow aB} , p B b : B b → b b {\displaystyle p_{Bb}:Bb\rightarrow bb} , p A a : A a → a a {\displaystyle p_{Aa}:Aa\rightarrow aa} .
A non contracting grammar (for which there is an equivalent CSG) for the language L C r o s s = { a m b n c m d n ∣ m ≥ 1 , n ≥ 1 } {\displaystyle L_{Cross}=\{a^{m}b^{n}c^{m}d^{n}\mid m\geq 1,n\geq 1\}} is defined by
With these definitions, a derivation for a 3 b 2 c 3 d 2 {\displaystyle a^{3}b^{2}c^{3}d^{2}} is: S ⇒ p 0 R T ⇒ p 1 2 p 2 a 3 C 3 T ⇒ p 3 p 4 a 3 C 3 B 2 d 2 ⇒ p 5 6 a 3 B 2 C 3 d 2 ⇒ p 6 p 7 a 3 b 2 C 3 d 2 ⇒ p 8 p 9 2 a 3 b 2 c 3 d 2 {\displaystyle S\Rightarrow _{p_{0}}RT\Rightarrow _{p_{1}^{2}p_{2}}a^{3}C^{3}T\Rightarrow _{p_{3}p_{4}}a^{3}C^{3}B^{2}d^{2}\Rightarrow _{p_{5}^{6}}a^{3}B^{2}C^{3}d^{2}\Rightarrow _{p_{6}p_{7}}a^{3}b^{2}C^{3}d^{2}\Rightarrow _{p_{8}p_{9}^{2}}a^{3}b^{2}c^{3}d^{2}} .
A noncontracting grammar for the language { a | i ≥ 1 } is constructed in Example 9.5 (p. 224) of (Hopcroft, Ullman, 1979):
Every context-sensitive grammar which does not generate the empty string can be transformed into a weakly equivalent one in Kuroda normal form. "Weakly equivalent" here means that the two grammars generate the same language. The normal form will not in general be context-sensitive, but will be a noncontracting grammar.
The Kuroda normal form is an actual normal form for non-contracting grammars.
A formal language can be described by a context-sensitive grammar if and only if it is accepted by some linear bounded automaton (LBA). In some textbooks this result is attributed solely to Landweber and Kuroda. Others call it the Myhill–Landweber–Kuroda theorem. (Myhill introduced the concept of deterministic LBA in 1960. Peter S. Landweber published in 1963 that the language accepted by a deterministic LBA is context sensitive. Kuroda introduced the notion of non-deterministic LBA and the equivalence between LBA and CSGs in 1964.)
As of 2010 it is still an open question whether every context-sensitive language can be accepted by a deterministic LBA.
Context-sensitive languages are closed under complement. This 1988 result is known as the Immerman–Szelepcsényi theorem. Moreover, they are closed under union, intersection, concatenation, substitution, inverse homomorphism, and Kleene plus.
Every recursively enumerable language L can be written as h(L) for some context-sensitive language L and some string homomorphism h.
The decision problem that asks whether a certain string s belongs to the language of a given context-sensitive grammar G, is PSPACE-complete. Moreover, there are context-sensitive grammars whose languages are PSPACE-complete. In other words, there is a context-sensitive grammar G such that deciding whether a certain string s belongs to the language of G is PSPACE-complete (so G is fixed and only s is part of the input of the problem).
The emptiness problem for context-sensitive grammars (given a context-sensitive grammar G, is L(G)=∅ ?) is undecidable.
Savitch has proven the following theoretical result, on which he bases his criticism of CSGs as basis for natural language: for any recursively enumerable set R, there exists a context-sensitive language/grammar G which can be used as a sort of proxy to test membership in R in the following way: given a string s, s is in R if and only if there exists a positive integer n for which sc is in G, where c is an arbitrary symbol not part of R.
It has been shown that nearly all natural languages may in general be characterized by context-sensitive grammars, but the whole class of CSGs seems to be much bigger than natural languages. Worse yet, since the aforementioned decision problem for CSGs is PSPACE-complete, that makes them totally unworkable for practical use, as a polynomial-time algorithm for a PSPACE-complete problem would imply P=NP.
It was proven that some natural languages are not context-free, based on identifying so-called cross-serial dependencies and unbounded scrambling phenomena. However this does not necessarily imply that the class of CSGs is necessary to capture "context sensitivity" in the colloquial sense of these terms in natural languages. For example, linear context-free rewriting systems (LCFRSs) are strictly weaker than CSGs but can account for the phenomenon of cross-serial dependencies; one can write a LCFRS grammar for {abcd | n ≥ 1} for example.
Ongoing research on computational linguistics has focused on formulating other classes of languages that are "mildly context-sensitive" whose decision problems are feasible, such as tree-adjoining grammars, combinatory categorial grammars, coupled context-free languages, and linear context-free rewriting systems. The languages generated by these formalisms properly lie between the context-free and context-sensitive languages.
More recently, the class PTIME has been identified with range concatenation grammars, which are now considered to be the most expressive of the mild-context sensitive language classes. | [
{
"paragraph_id": 0,
"text": "A context-sensitive grammar (CSG) is a formal grammar in which the left-hand sides and right-hand sides of any production rules may be surrounded by a context of terminal and nonterminal symbols. Context-sensitive grammars are more general than context-free grammars, in the sense that there are languages that can be described by a CSG but not by a context-free grammar. Context-sensitive grammars are less general (in the same sense) than unrestricted grammars. Thus, CSGs are positioned between context-free and unrestricted grammars in the Chomsky hierarchy.",
"title": ""
},
{
"paragraph_id": 1,
"text": "A formal language that can be described by a context-sensitive grammar, or, equivalently, by a noncontracting grammar or a linear bounded automaton, is called a context-sensitive language. Some textbooks actually define CSGs as non-contracting, although this is not how Noam Chomsky defined them in 1959. This choice of definition makes no difference in terms of the languages generated (i.e. the two definitions are weakly equivalent), but it does make a difference in terms of what grammars are structurally considered context-sensitive; the latter issue was analyzed by Chomsky in 1963.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Chomsky introduced context-sensitive grammars as a way to describe the syntax of natural language where it is often the case that a word may or may not be appropriate in a certain place depending on the context. Walter Savitch has criticized the terminology \"context-sensitive\" as misleading and proposed \"non-erasing\" as better explaining the distinction between a CSG and an unrestricted grammar.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Although it is well known that certain features of languages (e.g. cross-serial dependency) are not context-free, it is an open question how much of CSGs' expressive power is needed to capture the context sensitivity found in natural languages. Subsequent research in this area has focused on the more computationally tractable mildly context-sensitive languages. The syntaxes of some visual programming languages can be described by context-sensitive graph grammars.",
"title": ""
},
{
"paragraph_id": 4,
"text": "Let us notate a formal grammar as G = ( N , Σ , P , S ) {\\displaystyle G=(N,\\Sigma ,P,S)} , with N {\\displaystyle N} a set of nonterminal symbols, Σ {\\displaystyle \\Sigma } a set of terminal symbols, P {\\displaystyle P} a set of production rules, and S ∈ N {\\displaystyle S\\in N} the start symbol.",
"title": "Formal definition"
},
{
"paragraph_id": 5,
"text": "A string u ∈ ( N ∪ Σ ) ∗ {\\displaystyle u\\in (N\\cup \\Sigma )^{*}} directly yields, or directly derives to, a string v ∈ ( N ∪ Σ ) ∗ {\\displaystyle v\\in (N\\cup \\Sigma )^{*}} , denoted as u ⇒ v {\\displaystyle u\\Rightarrow v} , if v can be obtained from u by an application of some production rule in P, that is, if u = γ L δ {\\displaystyle u=\\gamma L\\delta } and v = γ R δ {\\displaystyle v=\\gamma R\\delta } , where ( L → R ) ∈ P {\\displaystyle (L\\to R)\\in P} is a production rule, and γ , δ ∈ ( N ∪ Σ ) ∗ {\\displaystyle \\gamma ,\\delta \\in (N\\cup \\Sigma )^{*}} is the unaffected left and right part of the string, respectively. More generally, u is said to yield, or derive to, v, denoted as u ⇒ ∗ v {\\displaystyle u\\Rightarrow ^{*}v} , if v can be obtained from u by repeated application of production rules, that is, if u = u 1 ⇒ . . . ⇒ u n = v {\\displaystyle u=u_{1}\\Rightarrow ...\\Rightarrow u_{n}=v} for some n ≥ 0 and some strings u 2 , . . . , u n − 1 ∈ ( N ∪ Σ ) ∗ {\\displaystyle u_{2},...,u_{n-1}\\in (N\\cup \\Sigma )^{*}} . In other words, the relation ⇒ ∗ {\\displaystyle \\Rightarrow ^{*}} is the reflexive transitive closure of the relation ⇒ {\\displaystyle \\Rightarrow } .",
"title": "Formal definition"
},
{
"paragraph_id": 6,
"text": "The language of the grammar G is the set of all terminal-symbol strings derivable from its start symbol, formally: L ( G ) = { w ∈ Σ ∗ ∣ S ⇒ ∗ w } {\\displaystyle L(G)=\\{w\\in \\Sigma ^{*}\\mid S\\Rightarrow ^{*}w\\}} . Derivations that do not end in a string composed of terminal symbols only are possible, but do not contribute to L(G).",
"title": "Formal definition"
},
{
"paragraph_id": 7,
"text": "A formal grammar is context-sensitive if each rule in P is either of the form S → ε {\\displaystyle S\\to \\varepsilon } where ε {\\displaystyle \\varepsilon } is the empty string, or of the form",
"title": "Formal definition"
},
{
"paragraph_id": 8,
"text": "with A ∈ N, α , β ∈ ( N ∪ Σ ∖ { S } ) ∗ {\\displaystyle \\alpha ,\\beta \\in (N\\cup \\Sigma \\setminus \\{S\\})^{*}} , and γ ∈ ( N ∪ Σ ∖ { S } ) + {\\displaystyle \\gamma \\in (N\\cup \\Sigma \\setminus \\{S\\})^{+}} .",
"title": "Formal definition"
},
{
"paragraph_id": 9,
"text": "The name context-sensitive is explained by the α and β that form the context of A and determine whether A can be replaced with γ or not. By contrast, in a context-free grammar, no context is present: the left hand side of every production rule is just a nonterminal.",
"title": "Formal definition"
},
{
"paragraph_id": 10,
"text": "The string γ is not allowed to be empty. Without this restriction, the resulting grammars become equal in power to unrestricted grammars.",
"title": "Formal definition"
},
{
"paragraph_id": 11,
"text": "A noncontracting grammar is a grammar in which for any production rule, of the form u → v, the length of u is less than or equal to the length of v.",
"title": "Formal definition"
},
{
"paragraph_id": 12,
"text": "Every context-sensitive grammar is noncontracting, while every noncontracting grammar can be converted into an equivalent context-sensitive grammar; the two classes are weakly equivalent.",
"title": "Formal definition"
},
{
"paragraph_id": 13,
"text": "Some authors use the term context-sensitive grammar to refer to noncontracting grammars in general.",
"title": "Formal definition"
},
{
"paragraph_id": 14,
"text": "The left-context- and right-context-sensitive grammars are defined by restricting the rules to just the form αA → αγ and to just Aβ → γβ, respectively. The languages generated by these grammars are also the full class of context-sensitive languages. The equivalence was established by Penttonen normal form.",
"title": "Formal definition"
},
{
"paragraph_id": 15,
"text": "The following context-sensitive grammar, with start symbol S, generates the canonical non-context-free language { abc | n ≥ 1 } :",
"title": "Examples"
},
{
"paragraph_id": 16,
"text": "Rules 1 and 2 allow for blowing-up S to aBC(BC); rules 3 to 6 allow for successively exchanging each CB to BC (four rules are needed for that since a rule CB → BC wouldn't fit into the scheme αAβ → αγβ); rules 7–10 allow replacing a non-terminals B and C with its corresponding terminals b and c respectively, provided it is in the right place. A generation chain for aaabbbccc is:",
"title": "Examples"
},
{
"paragraph_id": 17,
"text": "More complicated grammars can be used to parse { abcd | n ≥ 1 }, and other languages with even more letters. Here we show a simpler approach using non-contracting grammars: Start with a kernel of regular productions generating the sentential forms ( A B C D ) n a b c d {\\displaystyle (ABCD)^{n}abcd} and then include the non contracting productions p D a : D a → a D {\\displaystyle p_{Da}:Da\\rightarrow aD} , p D b : D b → b D {\\displaystyle p_{Db}:Db\\rightarrow bD} , p D c : D c → c D {\\displaystyle p_{Dc}:Dc\\rightarrow cD} , p D d : D d → d d {\\displaystyle p_{Dd}:Dd\\rightarrow dd} , p C a : C a → a C {\\displaystyle p_{Ca}:Ca\\rightarrow aC} , p C b : C b → b C {\\displaystyle p_{Cb}:Cb\\rightarrow bC} , p C c : C c → c c {\\displaystyle p_{Cc}:Cc\\rightarrow cc} , p B a : B a → a B {\\displaystyle p_{Ba}:Ba\\rightarrow aB} , p B b : B b → b b {\\displaystyle p_{Bb}:Bb\\rightarrow bb} , p A a : A a → a a {\\displaystyle p_{Aa}:Aa\\rightarrow aa} .",
"title": "Examples"
},
{
"paragraph_id": 18,
"text": "A non contracting grammar (for which there is an equivalent CSG) for the language L C r o s s = { a m b n c m d n ∣ m ≥ 1 , n ≥ 1 } {\\displaystyle L_{Cross}=\\{a^{m}b^{n}c^{m}d^{n}\\mid m\\geq 1,n\\geq 1\\}} is defined by",
"title": "Examples"
},
{
"paragraph_id": 19,
"text": "With these definitions, a derivation for a 3 b 2 c 3 d 2 {\\displaystyle a^{3}b^{2}c^{3}d^{2}} is: S ⇒ p 0 R T ⇒ p 1 2 p 2 a 3 C 3 T ⇒ p 3 p 4 a 3 C 3 B 2 d 2 ⇒ p 5 6 a 3 B 2 C 3 d 2 ⇒ p 6 p 7 a 3 b 2 C 3 d 2 ⇒ p 8 p 9 2 a 3 b 2 c 3 d 2 {\\displaystyle S\\Rightarrow _{p_{0}}RT\\Rightarrow _{p_{1}^{2}p_{2}}a^{3}C^{3}T\\Rightarrow _{p_{3}p_{4}}a^{3}C^{3}B^{2}d^{2}\\Rightarrow _{p_{5}^{6}}a^{3}B^{2}C^{3}d^{2}\\Rightarrow _{p_{6}p_{7}}a^{3}b^{2}C^{3}d^{2}\\Rightarrow _{p_{8}p_{9}^{2}}a^{3}b^{2}c^{3}d^{2}} .",
"title": "Examples"
},
{
"paragraph_id": 20,
"text": "A noncontracting grammar for the language { a | i ≥ 1 } is constructed in Example 9.5 (p. 224) of (Hopcroft, Ullman, 1979):",
"title": "Examples"
},
{
"paragraph_id": 21,
"text": "Every context-sensitive grammar which does not generate the empty string can be transformed into a weakly equivalent one in Kuroda normal form. \"Weakly equivalent\" here means that the two grammars generate the same language. The normal form will not in general be context-sensitive, but will be a noncontracting grammar.",
"title": "Kuroda normal form"
},
{
"paragraph_id": 22,
"text": "The Kuroda normal form is an actual normal form for non-contracting grammars.",
"title": "Kuroda normal form"
},
{
"paragraph_id": 23,
"text": "A formal language can be described by a context-sensitive grammar if and only if it is accepted by some linear bounded automaton (LBA). In some textbooks this result is attributed solely to Landweber and Kuroda. Others call it the Myhill–Landweber–Kuroda theorem. (Myhill introduced the concept of deterministic LBA in 1960. Peter S. Landweber published in 1963 that the language accepted by a deterministic LBA is context sensitive. Kuroda introduced the notion of non-deterministic LBA and the equivalence between LBA and CSGs in 1964.)",
"title": "Properties and uses"
},
{
"paragraph_id": 24,
"text": "As of 2010 it is still an open question whether every context-sensitive language can be accepted by a deterministic LBA.",
"title": "Properties and uses"
},
{
"paragraph_id": 25,
"text": "Context-sensitive languages are closed under complement. This 1988 result is known as the Immerman–Szelepcsényi theorem. Moreover, they are closed under union, intersection, concatenation, substitution, inverse homomorphism, and Kleene plus.",
"title": "Properties and uses"
},
{
"paragraph_id": 26,
"text": "Every recursively enumerable language L can be written as h(L) for some context-sensitive language L and some string homomorphism h.",
"title": "Properties and uses"
},
{
"paragraph_id": 27,
"text": "The decision problem that asks whether a certain string s belongs to the language of a given context-sensitive grammar G, is PSPACE-complete. Moreover, there are context-sensitive grammars whose languages are PSPACE-complete. In other words, there is a context-sensitive grammar G such that deciding whether a certain string s belongs to the language of G is PSPACE-complete (so G is fixed and only s is part of the input of the problem).",
"title": "Properties and uses"
},
{
"paragraph_id": 28,
"text": "The emptiness problem for context-sensitive grammars (given a context-sensitive grammar G, is L(G)=∅ ?) is undecidable.",
"title": "Properties and uses"
},
{
"paragraph_id": 29,
"text": "Savitch has proven the following theoretical result, on which he bases his criticism of CSGs as basis for natural language: for any recursively enumerable set R, there exists a context-sensitive language/grammar G which can be used as a sort of proxy to test membership in R in the following way: given a string s, s is in R if and only if there exists a positive integer n for which sc is in G, where c is an arbitrary symbol not part of R.",
"title": "Properties and uses"
},
{
"paragraph_id": 30,
"text": "It has been shown that nearly all natural languages may in general be characterized by context-sensitive grammars, but the whole class of CSGs seems to be much bigger than natural languages. Worse yet, since the aforementioned decision problem for CSGs is PSPACE-complete, that makes them totally unworkable for practical use, as a polynomial-time algorithm for a PSPACE-complete problem would imply P=NP.",
"title": "Properties and uses"
},
{
"paragraph_id": 31,
"text": "It was proven that some natural languages are not context-free, based on identifying so-called cross-serial dependencies and unbounded scrambling phenomena. However this does not necessarily imply that the class of CSGs is necessary to capture \"context sensitivity\" in the colloquial sense of these terms in natural languages. For example, linear context-free rewriting systems (LCFRSs) are strictly weaker than CSGs but can account for the phenomenon of cross-serial dependencies; one can write a LCFRS grammar for {abcd | n ≥ 1} for example.",
"title": "Properties and uses"
},
{
"paragraph_id": 32,
"text": "Ongoing research on computational linguistics has focused on formulating other classes of languages that are \"mildly context-sensitive\" whose decision problems are feasible, such as tree-adjoining grammars, combinatory categorial grammars, coupled context-free languages, and linear context-free rewriting systems. The languages generated by these formalisms properly lie between the context-free and context-sensitive languages.",
"title": "Properties and uses"
},
{
"paragraph_id": 33,
"text": "More recently, the class PTIME has been identified with range concatenation grammars, which are now considered to be the most expressive of the mild-context sensitive language classes.",
"title": "Properties and uses"
}
] | A context-sensitive grammar (CSG) is a formal grammar in which the left-hand sides and right-hand sides of any production rules may be surrounded by a context of terminal and nonterminal symbols. Context-sensitive grammars are more general than context-free grammars, in the sense that there are languages that can be described by a CSG but not by a context-free grammar. Context-sensitive grammars are less general than unrestricted grammars. Thus, CSGs are positioned between context-free and unrestricted grammars in the Chomsky hierarchy. A formal language that can be described by a context-sensitive grammar, or, equivalently, by a noncontracting grammar or a linear bounded automaton, is called a context-sensitive language. Some textbooks actually define CSGs as non-contracting, although this is not how Noam Chomsky defined them in 1959. This choice of definition makes no difference in terms of the languages generated, but it does make a difference in terms of what grammars are structurally considered context-sensitive; the latter issue was analyzed by Chomsky in 1963. Chomsky introduced context-sensitive grammars as a way to describe the syntax of natural language where it is often the case that a word may or may not be appropriate in a certain place depending on the context. Walter Savitch has criticized the terminology "context-sensitive" as misleading and proposed "non-erasing" as better explaining the distinction between a CSG and an unrestricted grammar. Although it is well known that certain features of languages are not context-free, it is an open question how much of CSGs' expressive power is needed to capture the context sensitivity found in natural languages. Subsequent research in this area has focused on the more computationally tractable mildly context-sensitive languages. The syntaxes of some visual programming languages can be described by context-sensitive graph grammars. | 2001-10-25T17:33:45Z | 2023-11-07T09:06:50Z | [
"Template:Not a typo",
"Template:See also",
"Template:As of",
"Template:Cite journal",
"Template:Cite web",
"Template:Short description",
"Template:Citation needed",
"Template:Cn",
"Template:Cite book",
"Template:Formal languages and grammars",
"Template:More citations needed section",
"Template:Update inline",
"Template:Reflist"
] | https://en.wikipedia.org/wiki/Context-sensitive_grammar |
6,212 | Context-sensitive language | In formal language theory, a context-sensitive language is a language that can be defined by a context-sensitive grammar (and equivalently by a noncontracting grammar). Context-sensitive is one of the four types of grammars in the Chomsky hierarchy.
Computationally, a context-sensitive language is equivalent to a linear bounded nondeterministic Turing machine, also called a linear bounded automaton. That is a non-deterministic Turing machine with a tape of only k n {\displaystyle kn} cells, where n {\displaystyle n} is the size of the input and k {\displaystyle k} is a constant associated with the machine. This means that every formal language that can be decided by such a machine is a context-sensitive language, and every context-sensitive language can be decided by such a machine.
This set of languages is also known as NLINSPACE or NSPACE(O(n)), because they can be accepted using linear space on a non-deterministic Turing machine. The class LINSPACE (or DSPACE(O(n))) is defined the same, except using a deterministic Turing machine. Clearly LINSPACE is a subset of NLINSPACE, but it is not known whether LINSPACE = NLINSPACE.
One of the simplest context-sensitive but not context-free languages is L = { a n b n c n : n ≥ 1 } {\displaystyle L=\{a^{n}b^{n}c^{n}:n\geq 1\}} : the language of all strings consisting of n occurrences of the symbol "a", then n "b"s, then n "c"s (abc, aabbcc, aaabbbccc, etc.). A superset of this language, called the Bach language, is defined as the set of all strings where "a", "b" and "c" (or any other set of three symbols) occurs equally often (aabccb, baabcaccb, etc.) and is also context-sensitive.
L can be shown to be a context-sensitive language by constructing a linear bounded automaton which accepts L. The language can easily be shown to be neither regular nor context-free by applying the respective pumping lemmas for each of the language classes to L.
Similarly:
L C r o s s = { a m b n c m d n : m ≥ 1 , n ≥ 1 } {\displaystyle L_{Cross}=\{a^{m}b^{n}c^{m}d^{n}:m\geq 1,n\geq 1\}} is another context-sensitive language; the corresponding context-sensitive grammar can be easily projected starting with two context-free grammars generating sentential forms in the formats a m C m {\displaystyle a^{m}C^{m}} and B n d n {\displaystyle B^{n}d^{n}} and then supplementing them with a permutation production like C B → B C {\displaystyle CB\rightarrow BC} , a new starting symbol and standard syntactic sugar.
L M U L 3 = { a m b n c m n : m ≥ 1 , n ≥ 1 } {\displaystyle L_{MUL3}=\{a^{m}b^{n}c^{mn}:m\geq 1,n\geq 1\}} is another context-sensitive language (the "3" in the name of this language is intended to mean a ternary alphabet); that is, the "product" operation defines a context-sensitive language (but the "sum" defines only a context-free language as the grammar S → a S c | R {\displaystyle S\rightarrow aSc|R} and R → b R c | b c {\displaystyle R\rightarrow bRc|bc} shows). Because of the commutative property of the product, the most intuitive grammar for L M U L 3 {\displaystyle L_{MUL3}} is ambiguous. This problem can be avoided considering a somehow more restrictive definition of the language, e.g. L O R D M U L 3 = { a m b n c m n : 1 < m < n } {\displaystyle L_{ORDMUL3}=\{a^{m}b^{n}c^{mn}:1<m<n\}} . This can be specialized to L M U L 1 = { a m n : m > 1 , n > 1 } {\displaystyle L_{MUL1}=\{a^{mn}:m>1,n>1\}} and, from this, to L m 2 = { a m 2 : m > 1 } {\displaystyle L_{m^{2}}=\{a^{m^{2}}:m>1\}} , L m 3 = { a m 3 : m > 1 } {\displaystyle L_{m^{3}}=\{a^{m^{3}}:m>1\}} , etc.
L R E P = { w | w | : w ∈ Σ ∗ } {\displaystyle L_{REP}=\{w^{|w|}:w\in \Sigma ^{*}\}} is a context-sensitive language. The corresponding context-sensitive grammar can be obtained as a generalization of the context-sensitive grammars for L S q u a r e = { w 2 : w ∈ Σ ∗ } {\displaystyle L_{Square}=\{w^{2}:w\in \Sigma ^{*}\}} , L C u b e = { w 3 : w ∈ Σ ∗ } {\displaystyle L_{Cube}=\{w^{3}:w\in \Sigma ^{*}\}} , etc.
L E X P = { a 2 n : n ≥ 1 } {\displaystyle L_{EXP}=\{a^{2^{n}}:n\geq 1\}} is a context-sensitive language.
L P R I M E S 2 = { w : | w | is prime } {\displaystyle L_{PRIMES2}=\{w:|w|{\mbox{ is prime }}\}} is a context-sensitive language (the "2" in the name of this language is intended to mean a binary alphabet). This was proved by Hartmanis using pumping lemmas for regular and context-free languages over a binary alphabet and, after that, sketching a linear bounded multitape automaton accepting L P R I M E S 2 {\displaystyle L_{PRIMES2}} .
L P R I M E S 1 = { a p : p is prime } {\displaystyle L_{PRIMES1}=\{a^{p}:p{\mbox{ is prime }}\}} is a context-sensitive language (the "1" in the name of this language is intended to mean an unary alphabet). This was credited by A. Salomaa to Matti Soittola by means of a linear bounded automaton over an unary alphabet (pages 213-214, exercise 6.8) and also to Marti Penttonen by means of a context-sensitive grammar also over an unary alphabet (See: Formal Languages by A. Salomaa, page 14, Example 2.5).
An example of recursive language that is not context-sensitive is any recursive language whose decision is an EXPSPACE-hard problem, say, the set of pairs of equivalent regular expressions with exponentiation. | [
{
"paragraph_id": 0,
"text": "In formal language theory, a context-sensitive language is a language that can be defined by a context-sensitive grammar (and equivalently by a noncontracting grammar). Context-sensitive is one of the four types of grammars in the Chomsky hierarchy.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Computationally, a context-sensitive language is equivalent to a linear bounded nondeterministic Turing machine, also called a linear bounded automaton. That is a non-deterministic Turing machine with a tape of only k n {\\displaystyle kn} cells, where n {\\displaystyle n} is the size of the input and k {\\displaystyle k} is a constant associated with the machine. This means that every formal language that can be decided by such a machine is a context-sensitive language, and every context-sensitive language can be decided by such a machine.",
"title": "Computational properties"
},
{
"paragraph_id": 2,
"text": "This set of languages is also known as NLINSPACE or NSPACE(O(n)), because they can be accepted using linear space on a non-deterministic Turing machine. The class LINSPACE (or DSPACE(O(n))) is defined the same, except using a deterministic Turing machine. Clearly LINSPACE is a subset of NLINSPACE, but it is not known whether LINSPACE = NLINSPACE.",
"title": "Computational properties"
},
{
"paragraph_id": 3,
"text": "One of the simplest context-sensitive but not context-free languages is L = { a n b n c n : n ≥ 1 } {\\displaystyle L=\\{a^{n}b^{n}c^{n}:n\\geq 1\\}} : the language of all strings consisting of n occurrences of the symbol \"a\", then n \"b\"s, then n \"c\"s (abc, aabbcc, aaabbbccc, etc.). A superset of this language, called the Bach language, is defined as the set of all strings where \"a\", \"b\" and \"c\" (or any other set of three symbols) occurs equally often (aabccb, baabcaccb, etc.) and is also context-sensitive.",
"title": "Examples"
},
{
"paragraph_id": 4,
"text": "L can be shown to be a context-sensitive language by constructing a linear bounded automaton which accepts L. The language can easily be shown to be neither regular nor context-free by applying the respective pumping lemmas for each of the language classes to L.",
"title": "Examples"
},
{
"paragraph_id": 5,
"text": "Similarly:",
"title": "Examples"
},
{
"paragraph_id": 6,
"text": "L C r o s s = { a m b n c m d n : m ≥ 1 , n ≥ 1 } {\\displaystyle L_{Cross}=\\{a^{m}b^{n}c^{m}d^{n}:m\\geq 1,n\\geq 1\\}} is another context-sensitive language; the corresponding context-sensitive grammar can be easily projected starting with two context-free grammars generating sentential forms in the formats a m C m {\\displaystyle a^{m}C^{m}} and B n d n {\\displaystyle B^{n}d^{n}} and then supplementing them with a permutation production like C B → B C {\\displaystyle CB\\rightarrow BC} , a new starting symbol and standard syntactic sugar.",
"title": "Examples"
},
{
"paragraph_id": 7,
"text": "L M U L 3 = { a m b n c m n : m ≥ 1 , n ≥ 1 } {\\displaystyle L_{MUL3}=\\{a^{m}b^{n}c^{mn}:m\\geq 1,n\\geq 1\\}} is another context-sensitive language (the \"3\" in the name of this language is intended to mean a ternary alphabet); that is, the \"product\" operation defines a context-sensitive language (but the \"sum\" defines only a context-free language as the grammar S → a S c | R {\\displaystyle S\\rightarrow aSc|R} and R → b R c | b c {\\displaystyle R\\rightarrow bRc|bc} shows). Because of the commutative property of the product, the most intuitive grammar for L M U L 3 {\\displaystyle L_{MUL3}} is ambiguous. This problem can be avoided considering a somehow more restrictive definition of the language, e.g. L O R D M U L 3 = { a m b n c m n : 1 < m < n } {\\displaystyle L_{ORDMUL3}=\\{a^{m}b^{n}c^{mn}:1<m<n\\}} . This can be specialized to L M U L 1 = { a m n : m > 1 , n > 1 } {\\displaystyle L_{MUL1}=\\{a^{mn}:m>1,n>1\\}} and, from this, to L m 2 = { a m 2 : m > 1 } {\\displaystyle L_{m^{2}}=\\{a^{m^{2}}:m>1\\}} , L m 3 = { a m 3 : m > 1 } {\\displaystyle L_{m^{3}}=\\{a^{m^{3}}:m>1\\}} , etc.",
"title": "Examples"
},
{
"paragraph_id": 8,
"text": "L R E P = { w | w | : w ∈ Σ ∗ } {\\displaystyle L_{REP}=\\{w^{|w|}:w\\in \\Sigma ^{*}\\}} is a context-sensitive language. The corresponding context-sensitive grammar can be obtained as a generalization of the context-sensitive grammars for L S q u a r e = { w 2 : w ∈ Σ ∗ } {\\displaystyle L_{Square}=\\{w^{2}:w\\in \\Sigma ^{*}\\}} , L C u b e = { w 3 : w ∈ Σ ∗ } {\\displaystyle L_{Cube}=\\{w^{3}:w\\in \\Sigma ^{*}\\}} , etc.",
"title": "Examples"
},
{
"paragraph_id": 9,
"text": "L E X P = { a 2 n : n ≥ 1 } {\\displaystyle L_{EXP}=\\{a^{2^{n}}:n\\geq 1\\}} is a context-sensitive language.",
"title": "Examples"
},
{
"paragraph_id": 10,
"text": "L P R I M E S 2 = { w : | w | is prime } {\\displaystyle L_{PRIMES2}=\\{w:|w|{\\mbox{ is prime }}\\}} is a context-sensitive language (the \"2\" in the name of this language is intended to mean a binary alphabet). This was proved by Hartmanis using pumping lemmas for regular and context-free languages over a binary alphabet and, after that, sketching a linear bounded multitape automaton accepting L P R I M E S 2 {\\displaystyle L_{PRIMES2}} .",
"title": "Examples"
},
{
"paragraph_id": 11,
"text": "L P R I M E S 1 = { a p : p is prime } {\\displaystyle L_{PRIMES1}=\\{a^{p}:p{\\mbox{ is prime }}\\}} is a context-sensitive language (the \"1\" in the name of this language is intended to mean an unary alphabet). This was credited by A. Salomaa to Matti Soittola by means of a linear bounded automaton over an unary alphabet (pages 213-214, exercise 6.8) and also to Marti Penttonen by means of a context-sensitive grammar also over an unary alphabet (See: Formal Languages by A. Salomaa, page 14, Example 2.5).",
"title": "Examples"
},
{
"paragraph_id": 12,
"text": "An example of recursive language that is not context-sensitive is any recursive language whose decision is an EXPSPACE-hard problem, say, the set of pairs of equivalent regular expressions with exponentiation.",
"title": "Examples"
}
] | In formal language theory, a context-sensitive language is a language that can be defined by a context-sensitive grammar. Context-sensitive is one of the four types of grammars in the Chomsky hierarchy. | 2001-10-12T00:36:30Z | 2023-10-23T17:17:58Z | [
"Template:Reflist",
"Template:Citation",
"Template:Cite conference",
"Template:Webarchive",
"Template:ISBN",
"Template:Formal languages and grammars",
"Template:Redirect",
"Template:Mvar",
"Template:Not a typo",
"Template:Cite journal",
"Template:Doi",
"Template:Cite book"
] | https://en.wikipedia.org/wiki/Context-sensitive_language |
6,216 | Chinese room | The Chinese room argument holds that a digital computer executing a program cannot have a "mind", "understanding", or "consciousness", regardless of how intelligently or human-like the program may make the computer behave. The argument was presented by philosopher John Searle in his paper "Minds, Brains, and Programs", published in Behavioral and Brain Sciences in 1980. Similar arguments were presented by Gottfried Leibniz (1714), Anatoly Dneprov (1961), Lawrence Davis (1974) and Ned Block (1978). Searle's version has been widely discussed in the years since. The centerpiece of Searle's argument is a thought experiment known as the Chinese room.
The argument is directed against the philosophical positions of functionalism and computationalism which hold that the mind may be viewed as an information-processing system operating on formal symbols, and that simulation of a given mental state is sufficient for its presence. Specifically, the argument is intended to refute a position Searle calls the strong AI hypothesis: "The appropriately programmed computer with the right inputs and outputs would thereby have a mind in exactly the same sense human beings have minds."
Although it was originally presented in reaction to the statements of artificial intelligence (AI) researchers, it is not an argument against the goals of mainstream AI research because it does not show a limit in the amount of "intelligent" behavior a machine can display. The argument applies only to digital computers running programs and does not apply to machines in general.
Searle's thought experiment begins with this hypothetical premise: suppose that artificial intelligence research has succeeded in constructing a computer that behaves as if it understands Chinese. It takes Chinese characters as input and, by following the instructions of a computer program, produces other Chinese characters, which it presents as output. Suppose, says Searle, that this computer performs its task so convincingly that it comfortably passes the Turing test: it convinces a human Chinese speaker that the program is itself a live Chinese speaker. To all of the questions that the person asks, it makes appropriate responses, such that any Chinese speaker would be convinced that they are talking to another Chinese-speaking human being.
The question Searle wants to answer is this: does the machine literally "understand" Chinese? Or is it merely simulating the ability to understand Chinese? Searle calls the first position "strong AI" and the latter "weak AI".
Searle then supposes that he is in a closed room and has a book with an English version of the computer program, along with sufficient papers, pencils, erasers, and filing cabinets. Searle could receive Chinese characters through a slot in the door, process them according to the program's instructions, and produce Chinese characters as output, without understanding any of the content of the Chinese writing. If the computer had passed the Turing test this way, it follows, says Searle, that he would do so as well, simply by running the program manually.
Searle asserts that there is no essential difference between the roles of the computer and himself in the experiment. Each simply follows a program, step-by-step, producing behavior that is then interpreted by the user as demonstrating intelligent conversation. However, Searle himself would not be able to understand the conversation. ("I don't speak a word of Chinese", he points out.) Therefore, he argues, it follows that the computer would not be able to understand the conversation either.
Searle argues that, without "understanding" (or "intentionality"), we cannot describe what the machine is doing as "thinking" and, since it does not think, it does not have a "mind" in anything like the normal sense of the word. Therefore, he concludes that the "strong AI" hypothesis is false.
Gottfried Leibniz made a similar argument in 1714 against mechanism (the idea that everything that makes up a human being could, in principle, be explained in mechanical terms. In other words that a person, including their mind, is merely a very complex machine). Leibniz used the thought experiment of expanding the brain until it was the size of a mill. Leibniz found it difficult to imagine that a "mind" capable of "perception" could be constructed using only mechanical processes.
Soviet cyberneticist Anatoly Dneprov made an essentially identical argument in 1961, in the form of the short story "The Game". In it, a stadium of people act as switches and memory cells implementing a program to translate a sentence of Portuguese, a language that none of them know. The game was organized by a "Professor Zarubin" to answer the question "Can mathematical machines think?" Speaking through Zarubin, Dneprov writes "the only way to prove that machines can think is to turn yourself into a machine and examine your thinking process" and he concludes, as Searle does, "We've proven that even the most perfect simulation of machine thinking is not the thinking process itself."
In 1974, Lawrence Davis imagined duplicating the brain using telephone lines and offices staffed by people, and in 1978 Ned Block envisioned the entire population of China involved in such a brain simulation. This thought experiment is called the China brain, also the "Chinese Nation" or the "Chinese Gym".
Searle's version appeared in his 1980 paper "Minds, Brains, and Programs", published in Behavioral and Brain Sciences. It eventually became the journal's "most influential target article", generating an enormous number of commentaries and responses in the ensuing decades, and Searle has continued to defend and refine the argument in many papers, popular articles and books. David Cole writes that "the Chinese Room argument has probably been the most widely discussed philosophical argument in cognitive science to appear in the past 25 years".
Most of the discussion consists of attempts to refute it. "The overwhelming majority", notes BBS editor Stevan Harnad, "still think that the Chinese Room Argument is dead wrong". The sheer volume of the literature that has grown up around it inspired Pat Hayes to comment that the field of cognitive science ought to be redefined as "the ongoing research program of showing Searle's Chinese Room Argument to be false".
Searle's argument has become "something of a classic in cognitive science", according to Harnad. Varol Akman agrees, and has described the original paper as "an exemplar of philosophical clarity and purity".
Although the Chinese Room argument was originally presented in reaction to the statements of artificial intelligence researchers, philosophers have come to consider it as an important part of the philosophy of mind. It is a challenge to functionalism and the computational theory of mind, and is related to such questions as the mind–body problem, the problem of other minds, the symbol-grounding problem, and the hard problem of consciousness.
Searle identified a philosophical position he calls "strong AI":
The appropriately programmed computer with the right inputs and outputs would thereby have a mind in exactly the same sense human beings have minds.
The definition depends on the distinction between simulating a mind and actually having a mind. Searle writes that "according to Strong AI, the correct simulation really is a mind. According to Weak AI, the correct simulation is a model of the mind."
The claim is implicit in some of the statements of early AI researchers and analysts. For example, in 1955, AI founder Herbert A. Simon declared that "there are now in the world machines that think, that learn and create". Simon, together with Allen Newell and Cliff Shaw, after having completed the first "AI" program, the Logic Theorist, claimed that they had "solved the venerable mind–body problem, explaining how a system composed of matter can have the properties of mind." John Haugeland wrote that "AI wants only the genuine article: machines with minds, in the full and literal sense. This is not science fiction, but real science, based on a theoretical conception as deep as it is daring: namely, we are, at root, computers ourselves."
Searle also ascribes the following claims to advocates of strong AI:
In more recent presentations of the Chinese room argument, Searle has identified "strong AI" as "computer functionalism" (a term he attributes to Daniel Dennett). Functionalism is a position in modern philosophy of mind that holds that we can define mental phenomena (such as beliefs, desires, and perceptions) by describing their functions in relation to each other and to the outside world. Because a computer program can accurately represent functional relationships as relationships between symbols, a computer can have mental phenomena if it runs the right program, according to functionalism.
Stevan Harnad argues that Searle's depictions of strong AI can be reformulated as "recognizable tenets of computationalism, a position (unlike "strong AI") that is actually held by many thinkers, and hence one worth refuting." Computationalism is the position in the philosophy of mind which argues that the mind can be accurately described as an information-processing system.
Each of the following, according to Harnad, is a "tenet" of computationalism:
Searle holds a philosophical position he calls "biological naturalism": that consciousness and understanding require specific biological machinery that are found in brains. He writes "brains cause minds" and that "actual human mental phenomena [are] dependent on actual physical–chemical properties of actual human brains". Searle argues that this machinery (known to neuroscience as the "neural correlates of consciousness") must have some causal powers that permit the human experience of consciousness. Searle's belief in the existence of these powers has been criticized.
Searle does not disagree with the notion that machines can have consciousness and understanding, because, as he writes, "we are precisely such machines". Searle holds that the brain is, in fact, a machine, but that the brain gives rise to consciousness and understanding using specific machinery. If neuroscience is able to isolate the mechanical process that gives rise to consciousness, then Searle grants that it may be possible to create machines that have consciousness and understanding. However, without the specific machinery required, Searle does not believe that consciousness can occur.
Biological naturalism implies that one cannot determine if the experience of consciousness is occurring merely by examining how a system functions, because the specific machinery of the brain is essential. Thus, biological naturalism is directly opposed to both behaviorism and functionalism (including "computer functionalism" or "strong AI"). Biological naturalism is similar to identity theory (the position that mental states are "identical to" or "composed of" neurological events); however, Searle has specific technical objections to identity theory. Searle's biological naturalism and strong AI are both opposed to Cartesian dualism, the classical idea that the brain and mind are made of different "substances". Indeed, Searle accuses strong AI of dualism, writing that "strong AI only makes sense given the dualistic assumption that, where the mind is concerned, the brain doesn't matter."
Searle's original presentation emphasized "understanding"—that is, mental states with what philosophers call "intentionality"—and did not directly address other closely related ideas such as "consciousness". However, in more recent presentations, Searle has included consciousness as the real target of the argument.
Computational models of consciousness are not sufficient by themselves for consciousness. The computational model for consciousness stands to consciousness in the same way the computational model of anything stands to the domain being modelled. Nobody supposes that the computational model of rainstorms in London will leave us all wet. But they make the mistake of supposing that the computational model of consciousness is somehow conscious. It is the same mistake in both cases.
David Chalmers writes, "it is fairly clear that consciousness is at the root of the matter" of the Chinese room.
Colin McGinn argues that the Chinese room provides strong evidence that the hard problem of consciousness is fundamentally insoluble. The argument, to be clear, is not about whether a machine can be conscious, but about whether it (or anything else for that matter) can be shown to be conscious. It is plain that any other method of probing the occupant of a Chinese room has the same difficulties in principle as exchanging questions and answers in Chinese. It is simply not possible to divine whether a conscious agency or some clever simulation inhabits the room.
Searle argues that this is only true for an observer outside of the room. The whole point of the thought experiment is to put someone inside the room, where they can directly observe the operations of consciousness. Searle claims that from his vantage point within the room there is nothing he can see that could imaginably give rise to consciousness, other than himself, and clearly he does not have a mind that can speak Chinese.
Patrick Hew used the Chinese Room argument to deduce requirements from military command and control systems if they are to preserve a commander's moral agency. He drew an analogy between a commander in their command center and the person in the Chinese Room, and analyzed it under a reading of Aristotle's notions of "compulsory" and "ignorance". Information could be "down converted" from meaning to symbols, and manipulated symbolically, but moral agency could be undermined if there was inadequate 'up conversion' into meaning. Hew cited examples from the USS Vincennes incident.
The Chinese room argument is primarily an argument in the philosophy of mind, and both major computer scientists and artificial intelligence researchers consider it irrelevant to their fields. However, several concepts developed by computer scientists are essential to understanding the argument, including symbol processing, Turing machines, Turing completeness, and the Turing test.
Searle's arguments are not usually considered an issue for AI research. The primary mission of artificial intelligence research is only to create useful systems that act intelligently and it does not matter if the intelligence is "merely" a simulation. AI researchers Stuart Russell and Peter Norvig wrote in 2021: "We are interested in programs that behave intelligently. Individual aspects of consciousness -- awareness, self-awareness, attention -- can be programmed and can be part of an intelligent machine. The additional project making a machine conscious in exactly the way humans are is not one that we are equipped to take on."
Searle does not disagree that AI research can create machines that are capable of highly intelligent behavior. The Chinese room argument leaves open the possibility that a digital machine could be built that acts more intelligently than a person, but does not have a mind or intentionality in the same way that brains do.
Searle's "strong AI hypothesis" should not be confused with "strong AI" as defined by Ray Kurzweil and other futurists, who use the term to describe machine intelligence that rivals or exceeds human intelligence -- that is, artificial general intelligence, human level AI or superintelligence. Kurzweil is referring primarily to the amount of intelligence displayed by the machine, whereas Searle's argument sets no limit on this. Searle argues that a superintelligent machine would not necessarily have a mind and consciousness.
The Chinese room implements a version of the Turing test. Alan Turing introduced the test in 1950 to help answer the question "can machines think?" In the standard version, a human judge engages in a natural language conversation with a human and a machine designed to generate performance indistinguishable from that of a human being. All participants are separated from one another. If the judge cannot reliably tell the machine from the human, the machine is said to have passed the test.
Turing then considered each possible objection to the proposal "machines can think", and found that there are simple, obvious answers if the question is de-mystified in this way. He did not, however, intend for the test to measure for the presence of "consciousness" or "understanding". He did not believe this was relevant to the issues that he was addressing. He wrote:
I do not wish to give the impression that I think there is no mystery about consciousness. There is, for instance, something of a paradox connected with any attempt to localise it. But I do not think these mysteries necessarily need to be solved before we can answer the question with which we are concerned in this paper.
To Searle, as a philosopher investigating in the nature of mind and consciousness, these are the relevant mysteries. The Chinese room is designed to show that the Turing test is insufficient to detect the presence of consciousness, even if the room can behave or function as a conscious mind would.
The Chinese room (and all modern computers) manipulate physical objects in order to carry out calculations and do simulations. AI researchers Allen Newell and Herbert A. Simon called this kind of machine a physical symbol system. It is also equivalent to the formal systems used in the field of mathematical logic.
Searle emphasizes the fact that this kind of symbol manipulation is syntactic (borrowing a term from the study of grammar). The computer manipulates the symbols using a form of syntax rules, without any knowledge of the symbol's semantics (that is, their meaning).
Newell and Simon had conjectured that a physical symbol system (such as a digital computer) had all the necessary machinery for "general intelligent action", or, as it is known today, artificial general intelligence. They framed this as a philosophical position, the physical symbol system hypothesis: "A physical symbol system has the necessary and sufficient means for general intelligent action." The Chinese room argument does not refute this, because it is framed in terms of "intelligent action", i.e. the external behavior of the machine, rather than the presence or absence of understanding, consciousness and mind.
Twenty-first century AI programs (such as "deep learning") do mathematical operations on huge matrixes of unidentified numbers and bear little resemblance to the symbolic processing used by AI programs at the time Searle wrote his critique in 1980. Nils Nilsson describes systems like these as "dynamic" rather than "symbolic". Nilsson notes that these are essentially digitized representations of dynamic systems -- the individual numbers do not have a specific semantics, but are instead samples or data points from a dynamic signal, and it is the signal being approximated which would have semantics. Nilsson argues it is not reasonable to consider these signals as "symbol processing" in the same sense as the physical symbol systems hypothesis.
The Chinese room has a design analogous to that of a modern computer. It has a Von Neumann architecture, which consists of a program (the book of instructions), some memory (the papers and file cabinets), a CPU that follows the instructions (the man), and a means to write symbols in memory (the pencil and eraser). A machine with this design is known in theoretical computer science as "Turing complete", because it has the necessary machinery to carry out any computation that a Turing machine can do, and therefore it is capable of doing a step-by-step simulation of any other digital machine, given enough memory and time. Alan Turing writes, "all digital computers are in a sense equivalent." The widely accepted Church–Turing thesis holds that any function computable by an effective procedure is computable by a Turing machine.
The Turing completeness of the Chinese room implies that it can do whatever any other digital computer can do (albeit much, much more slowly). Thus, if the Chinese room does not or can not contain a Chinese-speaking mind, then no other digital computer can contain a mind. Some replies to Searle begin by arguing that the room, as described, cannot have a Chinese-speaking mind. Arguments of this form, according to Stevan Harnad, are "no refutation (but rather an affirmation)" of the Chinese room argument, because these arguments actually imply that no digital computers can have a mind.
There are some critics, such as Hanoch Ben-Yami, who argue that the Chinese room cannot simulate all the abilities of a digital computer, such as being able to determine the current time.
Searle has produced a more formal version of the argument of which the Chinese Room forms a part. He presented the first version in 1984. The version given below is from 1990. The Chinese room thought experiment is intended to prove point A3.
He begins with three axioms:
Searle posits that these lead directly to this conclusion:
This much of the argument is intended to show that artificial intelligence can never produce a machine with a mind by writing programs that manipulate symbols. The remainder of the argument addresses a different issue. Is the human brain running a program? In other words, is the computational theory of mind correct? He begins with an axiom that is intended to express the basic modern scientific consensus about brains and minds:
Searle claims that we can derive "immediately" and "trivially" that:
And from this he derives the further conclusions:
Refutations of Searle's argument take many different forms (see below). Computationalists and functionalists reject A3, arguing that "syntax" (as Searle describes it) can have "semantics" if the syntax has the right functional structure. Eliminative materialists reject A2, arguing that minds don't actually have "semantics" -- that thoughts and other mental phenomena are inherently meaningless but nevertheless function as if they had meaning.
Replies to Searle's argument may be classified according to what they claim to show:
Some of the arguments (robot and brain simulation, for example) fall into multiple categories.
These replies attempt to answer the question: since the man in the room does not speak Chinese, where is the "mind" that does? These replies address the key ontological issues of mind vs. body and simulation vs. reality. All of the replies that identify the mind in the room are versions of "the system reply".
More sophisticated versions of the systems reply try to identify more precisely what "the system" is and they differ in exactly how they describe it. According to these replies, the "mind that speaks Chinese" could be such things as: the "software", a "program", a "running program", a simulation of the "neural correlates of consciousness", the "functional system", a "simulated mind", an "emergent property", or "a virtual mind" (described below).
These replies provide an explanation of exactly who it is that understands Chinese. If there is something besides the man in the room that can understand Chinese, Searle cannot argue that (1) the man does not understand Chinese, therefore (2) nothing in the room understands Chinese. This, according to those who make this reply, shows that Searle's argument fails to prove that "strong AI" is false.
These replies, by themselves, do not provide any evidence that strong AI is true, however. They do not show that the system (or the virtual mind) understands Chinese, other than the hypothetical premise that it passes the Turing Test. Searle argues that, if we are to consider Strong AI remotely plausible, the Chinese Room is an example that requires explanation, and it is difficult or impossible to explain how consciousness might "emerge" from the room or how the system would have consciousness. As Searle writes "the systems reply simply begs the question by insisting that the system must understand Chinese" and thus is dodging the question or hopelessly circular.
As far as the person in the room is concerned, the symbols are just meaningless "squiggles." But if the Chinese room really "understands" what it is saying, then the symbols must get their meaning from somewhere. These arguments attempt to connect the symbols to the things they symbolize. These replies address Searle's concerns about intentionality, symbol grounding and syntax vs. semantics.
To each of these suggestions, Searle's response is the same: no matter how much knowledge is written into the program and no matter how the program is connected to the world, he is still in the room manipulating symbols according to rules. His actions are syntactic and this can never explain to him what the symbols stand for. Searle writes "syntax is insufficient for semantics."
However, for those who accept that Searle's actions simulate a mind, separate from his own, the important question is not what the symbols mean to Searle, what is important is what they mean to the virtual mind. While Searle is trapped in the room, the virtual mind is not: it is connected to the outside world through the Chinese speakers it speaks to, through the programmers who gave it world knowledge, and through the cameras and other sensors that roboticists can supply.
These arguments are all versions of the systems reply that identify a particular kind of system as being important; they identify some special technology that would create conscious understanding in a machine. (The "robot" and "commonsense knowledge" replies above also specify a certain kind of system as being important.)
[I]magine that instead of a monolingual man in a room shuffling symbols we have the man operate an elaborate set of water pipes with valves connecting them. When the man receives the Chinese symbols, he looks up in the program, written in English, which valves he has to turn on and off. Each water connection corresponds to a synapse in the Chinese brain, and the whole system is rigged up so that after doing all the right firings, that is after turning on all the right faucets, the Chinese answers pop out at the output end of the series of pipes. Now where is the understanding in this system? It takes Chinese as input, it simulates the formal structure of the synapses of the Chinese brain, and it gives Chinese as output. But the man certainly doesn't understand Chinese, and neither do the water pipes, and if we are tempted to adopt what I think is the absurd view that somehow the conjunction of man and water pipes understands, remember that in principle the man can internalize the formal structure of the water pipes and do all the "neuron firings" in his imagination.
Two variations on the brain simulator reply are the China brain and the brain-replacement scenario.
These arguments (and the robot or commonsense knowledge replies) identify some special technology that would help create conscious understanding in a machine. They may be interpreted in two ways: either they claim (1) this technology is required for consciousness, the Chinese room does not or cannot implement this technology, and therefore the Chinese room cannot pass the Turing test or (even if it did) it would not have conscious understanding. Or they may be claiming that (2) it is easier to see that the Chinese room has a mind if we visualize this technology as being used to create it.
In the first case, where features like a robot body or a connectionist architecture are required, Searle claims that strong AI (as he understands it) has been abandoned. The Chinese room has all the elements of a Turing complete machine, and thus is capable of simulating any digital computation whatsoever. If Searle's room cannot pass the Turing test then there is no other digital technology that could pass the Turing test. If Searle's room could pass the Turing test, but still does not have a mind, then the Turing test is not sufficient to determine if the room has a "mind". Either way, it denies one or the other of the positions Searle thinks of as "strong AI", proving his argument.
The brain arguments in particular deny strong AI if they assume that there is no simpler way to describe the mind than to create a program that is just as mysterious as the brain was. He writes "I thought the whole idea of strong AI was that we don't need to know how the brain works to know how the mind works." If computation does not provide an explanation of the human mind, then strong AI has failed, according to Searle.
Other critics hold that the room as Searle described it does, in fact, have a mind, however they argue that it is difficult to see—Searle's description is correct, but misleading. By redesigning the room more realistically they hope to make this more obvious. In this case, these arguments are being used as appeals to intuition (see next section).
In fact, the room can just as easily be redesigned to weaken our intuitions. Ned Block's Blockhead argument suggests that the program could, in theory, be rewritten into a simple lookup table of rules of the form "if the user writes S, reply with P and goto X". At least in principle, any program can be rewritten (or "refactored") into this form, even a brain simulation. In the blockhead scenario, the entire mental state is hidden in the letter X, which represents a memory address—a number associated with the next rule. It is hard to visualize that an instant of one's conscious experience can be captured in a single large number, yet this is exactly what "strong AI" claims. On the other hand, such a lookup table would be ridiculously large (to the point of being physically impossible), and the states could therefore be extremely specific.
Searle argues that however the program is written or however the machine is connected to the world, the mind is being simulated by a simple step-by-step digital machine (or machines). These machines are always just like the man in the room: they understand nothing and do not speak Chinese. They are merely manipulating symbols without knowing what they mean. Searle writes: "I can have any formal program you like, but I still understand nothing."
The following arguments (and the intuitive interpretations of the arguments above) do not directly explain how a Chinese speaking mind could exist in Searle's room, or how the symbols he manipulates could become meaningful. However, by raising doubts about Searle's intuitions they support other positions, such as the system and robot replies. These arguments, if accepted, prevent Searle from claiming that his conclusion is obvious by undermining the intuitions that his certainty requires.
Several critics believe that Searle's argument relies entirely on intuitions. Ned Block writes "Searle's argument depends for its force on intuitions that certain entities do not think." Daniel Dennett describes the Chinese room argument as a misleading "intuition pump" and writes "Searle's thought experiment depends, illicitly, on your imagining too simple a case, an irrelevant case, and drawing the 'obvious' conclusion from it."
Some of the arguments above also function as appeals to intuition, especially those that are intended to make it seem more plausible that the Chinese room contains a mind, which can include the robot, commonsense knowledge, brain simulation and connectionist replies. Several of the replies above also address the specific issue of complexity. The connectionist reply emphasizes that a working artificial intelligence system would have to be as complex and as interconnected as the human brain. The commonsense knowledge reply emphasizes that any program that passed a Turing test would have to be "an extraordinarily supple, sophisticated, and multilayered system, brimming with 'world knowledge' and meta-knowledge and meta-meta-knowledge", as Daniel Dennett explains.
Searle argues that his critics are also relying on intuitions, however his opponents' intuitions have no empirical basis. He writes that, in order to consider the "system reply" as remotely plausible, a person must be "under the grip of an ideology". The system reply only makes sense (to Searle) if one assumes that any "system" can have consciousness, just by virtue of being a system with the right behavior and functional parts. This assumption, he argues, is not tenable given our experience of consciousness.
Several replies argue that Searle's argument is irrelevant because his assumptions about the mind and consciousness are faulty. Searle believes that human beings directly experience their consciousness, intentionality and the nature of the mind every day, and that this experience of consciousness is not open to question. He writes that we must "presuppose the reality and knowability of the mental." The replies below question whether Searle is justified in using his own experience of consciousness to determine that it is more than mechanical symbol processing. In particular, the other minds reply argues that we cannot use our experience of consciousness to answer questions about other minds (even the mind of a computer), the epiphenoma replies question whether we can make any argument at all about something like consciousness which can not, by definition, be detected by any experiment, and the eliminative materialist reply argues that Searle's own personal consciousness does not "exist" in the sense that Searle thinks it does,
Searle disagrees with this analysis and argues that "the study of the mind starts with such facts as that humans have beliefs, while thermostats, telephones, and adding machines don't ... what we wanted to know is what distinguishes the mind from thermostats and livers." He takes it as obvious that we can detect the presence of consciousness and dismisses these replies as being off the point.
Margaret Boden argued in her paper "Escaping from the Chinese Room" that even if the person in the room does not understand the Chinese, it does not mean there is no understanding in the room. The person in the room at least understands the rule book used to provide output responses.
The Chinese room argument is a central concept in Peter Watts's novels Blindsight and (to a lesser extent) Echopraxia. Greg Egan illustrates the concept succinctly (and somewhat horrifically) in his 1990 short story Learning to Be Me, in his collection Axiomatic.
It is a central theme in the video game Zero Escape: Virtue's Last Reward, and ties into the game's narrative.
A similar human computer is imagined in Liu Cixin's novel The Three-Body Problem, described thus by Philip Steiner: "a massive human-computer by instrumentalizing millions of soldiers [who] take the role of signal input and signal output and are instructed to perform different logical circuits, like an AND gate and an OR gate". | [
{
"paragraph_id": 0,
"text": "The Chinese room argument holds that a digital computer executing a program cannot have a \"mind\", \"understanding\", or \"consciousness\", regardless of how intelligently or human-like the program may make the computer behave. The argument was presented by philosopher John Searle in his paper \"Minds, Brains, and Programs\", published in Behavioral and Brain Sciences in 1980. Similar arguments were presented by Gottfried Leibniz (1714), Anatoly Dneprov (1961), Lawrence Davis (1974) and Ned Block (1978). Searle's version has been widely discussed in the years since. The centerpiece of Searle's argument is a thought experiment known as the Chinese room.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The argument is directed against the philosophical positions of functionalism and computationalism which hold that the mind may be viewed as an information-processing system operating on formal symbols, and that simulation of a given mental state is sufficient for its presence. Specifically, the argument is intended to refute a position Searle calls the strong AI hypothesis: \"The appropriately programmed computer with the right inputs and outputs would thereby have a mind in exactly the same sense human beings have minds.\"",
"title": ""
},
{
"paragraph_id": 2,
"text": "Although it was originally presented in reaction to the statements of artificial intelligence (AI) researchers, it is not an argument against the goals of mainstream AI research because it does not show a limit in the amount of \"intelligent\" behavior a machine can display. The argument applies only to digital computers running programs and does not apply to machines in general.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Searle's thought experiment begins with this hypothetical premise: suppose that artificial intelligence research has succeeded in constructing a computer that behaves as if it understands Chinese. It takes Chinese characters as input and, by following the instructions of a computer program, produces other Chinese characters, which it presents as output. Suppose, says Searle, that this computer performs its task so convincingly that it comfortably passes the Turing test: it convinces a human Chinese speaker that the program is itself a live Chinese speaker. To all of the questions that the person asks, it makes appropriate responses, such that any Chinese speaker would be convinced that they are talking to another Chinese-speaking human being.",
"title": "Chinese room thought experiment"
},
{
"paragraph_id": 4,
"text": "The question Searle wants to answer is this: does the machine literally \"understand\" Chinese? Or is it merely simulating the ability to understand Chinese? Searle calls the first position \"strong AI\" and the latter \"weak AI\".",
"title": "Chinese room thought experiment"
},
{
"paragraph_id": 5,
"text": "Searle then supposes that he is in a closed room and has a book with an English version of the computer program, along with sufficient papers, pencils, erasers, and filing cabinets. Searle could receive Chinese characters through a slot in the door, process them according to the program's instructions, and produce Chinese characters as output, without understanding any of the content of the Chinese writing. If the computer had passed the Turing test this way, it follows, says Searle, that he would do so as well, simply by running the program manually.",
"title": "Chinese room thought experiment"
},
{
"paragraph_id": 6,
"text": "Searle asserts that there is no essential difference between the roles of the computer and himself in the experiment. Each simply follows a program, step-by-step, producing behavior that is then interpreted by the user as demonstrating intelligent conversation. However, Searle himself would not be able to understand the conversation. (\"I don't speak a word of Chinese\", he points out.) Therefore, he argues, it follows that the computer would not be able to understand the conversation either.",
"title": "Chinese room thought experiment"
},
{
"paragraph_id": 7,
"text": "Searle argues that, without \"understanding\" (or \"intentionality\"), we cannot describe what the machine is doing as \"thinking\" and, since it does not think, it does not have a \"mind\" in anything like the normal sense of the word. Therefore, he concludes that the \"strong AI\" hypothesis is false.",
"title": "Chinese room thought experiment"
},
{
"paragraph_id": 8,
"text": "Gottfried Leibniz made a similar argument in 1714 against mechanism (the idea that everything that makes up a human being could, in principle, be explained in mechanical terms. In other words that a person, including their mind, is merely a very complex machine). Leibniz used the thought experiment of expanding the brain until it was the size of a mill. Leibniz found it difficult to imagine that a \"mind\" capable of \"perception\" could be constructed using only mechanical processes.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "Soviet cyberneticist Anatoly Dneprov made an essentially identical argument in 1961, in the form of the short story \"The Game\". In it, a stadium of people act as switches and memory cells implementing a program to translate a sentence of Portuguese, a language that none of them know. The game was organized by a \"Professor Zarubin\" to answer the question \"Can mathematical machines think?\" Speaking through Zarubin, Dneprov writes \"the only way to prove that machines can think is to turn yourself into a machine and examine your thinking process\" and he concludes, as Searle does, \"We've proven that even the most perfect simulation of machine thinking is not the thinking process itself.\"",
"title": "History"
},
{
"paragraph_id": 10,
"text": "In 1974, Lawrence Davis imagined duplicating the brain using telephone lines and offices staffed by people, and in 1978 Ned Block envisioned the entire population of China involved in such a brain simulation. This thought experiment is called the China brain, also the \"Chinese Nation\" or the \"Chinese Gym\".",
"title": "History"
},
{
"paragraph_id": 11,
"text": "Searle's version appeared in his 1980 paper \"Minds, Brains, and Programs\", published in Behavioral and Brain Sciences. It eventually became the journal's \"most influential target article\", generating an enormous number of commentaries and responses in the ensuing decades, and Searle has continued to defend and refine the argument in many papers, popular articles and books. David Cole writes that \"the Chinese Room argument has probably been the most widely discussed philosophical argument in cognitive science to appear in the past 25 years\".",
"title": "History"
},
{
"paragraph_id": 12,
"text": "Most of the discussion consists of attempts to refute it. \"The overwhelming majority\", notes BBS editor Stevan Harnad, \"still think that the Chinese Room Argument is dead wrong\". The sheer volume of the literature that has grown up around it inspired Pat Hayes to comment that the field of cognitive science ought to be redefined as \"the ongoing research program of showing Searle's Chinese Room Argument to be false\".",
"title": "History"
},
{
"paragraph_id": 13,
"text": "Searle's argument has become \"something of a classic in cognitive science\", according to Harnad. Varol Akman agrees, and has described the original paper as \"an exemplar of philosophical clarity and purity\".",
"title": "History"
},
{
"paragraph_id": 14,
"text": "Although the Chinese Room argument was originally presented in reaction to the statements of artificial intelligence researchers, philosophers have come to consider it as an important part of the philosophy of mind. It is a challenge to functionalism and the computational theory of mind, and is related to such questions as the mind–body problem, the problem of other minds, the symbol-grounding problem, and the hard problem of consciousness.",
"title": "Philosophy"
},
{
"paragraph_id": 15,
"text": "Searle identified a philosophical position he calls \"strong AI\":",
"title": "Philosophy"
},
{
"paragraph_id": 16,
"text": "The appropriately programmed computer with the right inputs and outputs would thereby have a mind in exactly the same sense human beings have minds.",
"title": "Philosophy"
},
{
"paragraph_id": 17,
"text": "The definition depends on the distinction between simulating a mind and actually having a mind. Searle writes that \"according to Strong AI, the correct simulation really is a mind. According to Weak AI, the correct simulation is a model of the mind.\"",
"title": "Philosophy"
},
{
"paragraph_id": 18,
"text": "The claim is implicit in some of the statements of early AI researchers and analysts. For example, in 1955, AI founder Herbert A. Simon declared that \"there are now in the world machines that think, that learn and create\". Simon, together with Allen Newell and Cliff Shaw, after having completed the first \"AI\" program, the Logic Theorist, claimed that they had \"solved the venerable mind–body problem, explaining how a system composed of matter can have the properties of mind.\" John Haugeland wrote that \"AI wants only the genuine article: machines with minds, in the full and literal sense. This is not science fiction, but real science, based on a theoretical conception as deep as it is daring: namely, we are, at root, computers ourselves.\"",
"title": "Philosophy"
},
{
"paragraph_id": 19,
"text": "Searle also ascribes the following claims to advocates of strong AI:",
"title": "Philosophy"
},
{
"paragraph_id": 20,
"text": "In more recent presentations of the Chinese room argument, Searle has identified \"strong AI\" as \"computer functionalism\" (a term he attributes to Daniel Dennett). Functionalism is a position in modern philosophy of mind that holds that we can define mental phenomena (such as beliefs, desires, and perceptions) by describing their functions in relation to each other and to the outside world. Because a computer program can accurately represent functional relationships as relationships between symbols, a computer can have mental phenomena if it runs the right program, according to functionalism.",
"title": "Philosophy"
},
{
"paragraph_id": 21,
"text": "Stevan Harnad argues that Searle's depictions of strong AI can be reformulated as \"recognizable tenets of computationalism, a position (unlike \"strong AI\") that is actually held by many thinkers, and hence one worth refuting.\" Computationalism is the position in the philosophy of mind which argues that the mind can be accurately described as an information-processing system.",
"title": "Philosophy"
},
{
"paragraph_id": 22,
"text": "Each of the following, according to Harnad, is a \"tenet\" of computationalism:",
"title": "Philosophy"
},
{
"paragraph_id": 23,
"text": "Searle holds a philosophical position he calls \"biological naturalism\": that consciousness and understanding require specific biological machinery that are found in brains. He writes \"brains cause minds\" and that \"actual human mental phenomena [are] dependent on actual physical–chemical properties of actual human brains\". Searle argues that this machinery (known to neuroscience as the \"neural correlates of consciousness\") must have some causal powers that permit the human experience of consciousness. Searle's belief in the existence of these powers has been criticized.",
"title": "Philosophy"
},
{
"paragraph_id": 24,
"text": "Searle does not disagree with the notion that machines can have consciousness and understanding, because, as he writes, \"we are precisely such machines\". Searle holds that the brain is, in fact, a machine, but that the brain gives rise to consciousness and understanding using specific machinery. If neuroscience is able to isolate the mechanical process that gives rise to consciousness, then Searle grants that it may be possible to create machines that have consciousness and understanding. However, without the specific machinery required, Searle does not believe that consciousness can occur.",
"title": "Philosophy"
},
{
"paragraph_id": 25,
"text": "Biological naturalism implies that one cannot determine if the experience of consciousness is occurring merely by examining how a system functions, because the specific machinery of the brain is essential. Thus, biological naturalism is directly opposed to both behaviorism and functionalism (including \"computer functionalism\" or \"strong AI\"). Biological naturalism is similar to identity theory (the position that mental states are \"identical to\" or \"composed of\" neurological events); however, Searle has specific technical objections to identity theory. Searle's biological naturalism and strong AI are both opposed to Cartesian dualism, the classical idea that the brain and mind are made of different \"substances\". Indeed, Searle accuses strong AI of dualism, writing that \"strong AI only makes sense given the dualistic assumption that, where the mind is concerned, the brain doesn't matter.\"",
"title": "Philosophy"
},
{
"paragraph_id": 26,
"text": "Searle's original presentation emphasized \"understanding\"—that is, mental states with what philosophers call \"intentionality\"—and did not directly address other closely related ideas such as \"consciousness\". However, in more recent presentations, Searle has included consciousness as the real target of the argument.",
"title": "Philosophy"
},
{
"paragraph_id": 27,
"text": "Computational models of consciousness are not sufficient by themselves for consciousness. The computational model for consciousness stands to consciousness in the same way the computational model of anything stands to the domain being modelled. Nobody supposes that the computational model of rainstorms in London will leave us all wet. But they make the mistake of supposing that the computational model of consciousness is somehow conscious. It is the same mistake in both cases.",
"title": "Philosophy"
},
{
"paragraph_id": 28,
"text": "David Chalmers writes, \"it is fairly clear that consciousness is at the root of the matter\" of the Chinese room.",
"title": "Philosophy"
},
{
"paragraph_id": 29,
"text": "Colin McGinn argues that the Chinese room provides strong evidence that the hard problem of consciousness is fundamentally insoluble. The argument, to be clear, is not about whether a machine can be conscious, but about whether it (or anything else for that matter) can be shown to be conscious. It is plain that any other method of probing the occupant of a Chinese room has the same difficulties in principle as exchanging questions and answers in Chinese. It is simply not possible to divine whether a conscious agency or some clever simulation inhabits the room.",
"title": "Philosophy"
},
{
"paragraph_id": 30,
"text": "Searle argues that this is only true for an observer outside of the room. The whole point of the thought experiment is to put someone inside the room, where they can directly observe the operations of consciousness. Searle claims that from his vantage point within the room there is nothing he can see that could imaginably give rise to consciousness, other than himself, and clearly he does not have a mind that can speak Chinese.",
"title": "Philosophy"
},
{
"paragraph_id": 31,
"text": "Patrick Hew used the Chinese Room argument to deduce requirements from military command and control systems if they are to preserve a commander's moral agency. He drew an analogy between a commander in their command center and the person in the Chinese Room, and analyzed it under a reading of Aristotle's notions of \"compulsory\" and \"ignorance\". Information could be \"down converted\" from meaning to symbols, and manipulated symbolically, but moral agency could be undermined if there was inadequate 'up conversion' into meaning. Hew cited examples from the USS Vincennes incident.",
"title": "Philosophy"
},
{
"paragraph_id": 32,
"text": "The Chinese room argument is primarily an argument in the philosophy of mind, and both major computer scientists and artificial intelligence researchers consider it irrelevant to their fields. However, several concepts developed by computer scientists are essential to understanding the argument, including symbol processing, Turing machines, Turing completeness, and the Turing test.",
"title": "Computer science"
},
{
"paragraph_id": 33,
"text": "Searle's arguments are not usually considered an issue for AI research. The primary mission of artificial intelligence research is only to create useful systems that act intelligently and it does not matter if the intelligence is \"merely\" a simulation. AI researchers Stuart Russell and Peter Norvig wrote in 2021: \"We are interested in programs that behave intelligently. Individual aspects of consciousness -- awareness, self-awareness, attention -- can be programmed and can be part of an intelligent machine. The additional project making a machine conscious in exactly the way humans are is not one that we are equipped to take on.\"",
"title": "Computer science"
},
{
"paragraph_id": 34,
"text": "Searle does not disagree that AI research can create machines that are capable of highly intelligent behavior. The Chinese room argument leaves open the possibility that a digital machine could be built that acts more intelligently than a person, but does not have a mind or intentionality in the same way that brains do.",
"title": "Computer science"
},
{
"paragraph_id": 35,
"text": "Searle's \"strong AI hypothesis\" should not be confused with \"strong AI\" as defined by Ray Kurzweil and other futurists, who use the term to describe machine intelligence that rivals or exceeds human intelligence -- that is, artificial general intelligence, human level AI or superintelligence. Kurzweil is referring primarily to the amount of intelligence displayed by the machine, whereas Searle's argument sets no limit on this. Searle argues that a superintelligent machine would not necessarily have a mind and consciousness.",
"title": "Computer science"
},
{
"paragraph_id": 36,
"text": "The Chinese room implements a version of the Turing test. Alan Turing introduced the test in 1950 to help answer the question \"can machines think?\" In the standard version, a human judge engages in a natural language conversation with a human and a machine designed to generate performance indistinguishable from that of a human being. All participants are separated from one another. If the judge cannot reliably tell the machine from the human, the machine is said to have passed the test.",
"title": "Computer science"
},
{
"paragraph_id": 37,
"text": "Turing then considered each possible objection to the proposal \"machines can think\", and found that there are simple, obvious answers if the question is de-mystified in this way. He did not, however, intend for the test to measure for the presence of \"consciousness\" or \"understanding\". He did not believe this was relevant to the issues that he was addressing. He wrote:",
"title": "Computer science"
},
{
"paragraph_id": 38,
"text": "I do not wish to give the impression that I think there is no mystery about consciousness. There is, for instance, something of a paradox connected with any attempt to localise it. But I do not think these mysteries necessarily need to be solved before we can answer the question with which we are concerned in this paper.",
"title": "Computer science"
},
{
"paragraph_id": 39,
"text": "To Searle, as a philosopher investigating in the nature of mind and consciousness, these are the relevant mysteries. The Chinese room is designed to show that the Turing test is insufficient to detect the presence of consciousness, even if the room can behave or function as a conscious mind would.",
"title": "Computer science"
},
{
"paragraph_id": 40,
"text": "The Chinese room (and all modern computers) manipulate physical objects in order to carry out calculations and do simulations. AI researchers Allen Newell and Herbert A. Simon called this kind of machine a physical symbol system. It is also equivalent to the formal systems used in the field of mathematical logic.",
"title": "Computer science"
},
{
"paragraph_id": 41,
"text": "Searle emphasizes the fact that this kind of symbol manipulation is syntactic (borrowing a term from the study of grammar). The computer manipulates the symbols using a form of syntax rules, without any knowledge of the symbol's semantics (that is, their meaning).",
"title": "Computer science"
},
{
"paragraph_id": 42,
"text": "Newell and Simon had conjectured that a physical symbol system (such as a digital computer) had all the necessary machinery for \"general intelligent action\", or, as it is known today, artificial general intelligence. They framed this as a philosophical position, the physical symbol system hypothesis: \"A physical symbol system has the necessary and sufficient means for general intelligent action.\" The Chinese room argument does not refute this, because it is framed in terms of \"intelligent action\", i.e. the external behavior of the machine, rather than the presence or absence of understanding, consciousness and mind.",
"title": "Computer science"
},
{
"paragraph_id": 43,
"text": "Twenty-first century AI programs (such as \"deep learning\") do mathematical operations on huge matrixes of unidentified numbers and bear little resemblance to the symbolic processing used by AI programs at the time Searle wrote his critique in 1980. Nils Nilsson describes systems like these as \"dynamic\" rather than \"symbolic\". Nilsson notes that these are essentially digitized representations of dynamic systems -- the individual numbers do not have a specific semantics, but are instead samples or data points from a dynamic signal, and it is the signal being approximated which would have semantics. Nilsson argues it is not reasonable to consider these signals as \"symbol processing\" in the same sense as the physical symbol systems hypothesis.",
"title": "Computer science"
},
{
"paragraph_id": 44,
"text": "The Chinese room has a design analogous to that of a modern computer. It has a Von Neumann architecture, which consists of a program (the book of instructions), some memory (the papers and file cabinets), a CPU that follows the instructions (the man), and a means to write symbols in memory (the pencil and eraser). A machine with this design is known in theoretical computer science as \"Turing complete\", because it has the necessary machinery to carry out any computation that a Turing machine can do, and therefore it is capable of doing a step-by-step simulation of any other digital machine, given enough memory and time. Alan Turing writes, \"all digital computers are in a sense equivalent.\" The widely accepted Church–Turing thesis holds that any function computable by an effective procedure is computable by a Turing machine.",
"title": "Computer science"
},
{
"paragraph_id": 45,
"text": "The Turing completeness of the Chinese room implies that it can do whatever any other digital computer can do (albeit much, much more slowly). Thus, if the Chinese room does not or can not contain a Chinese-speaking mind, then no other digital computer can contain a mind. Some replies to Searle begin by arguing that the room, as described, cannot have a Chinese-speaking mind. Arguments of this form, according to Stevan Harnad, are \"no refutation (but rather an affirmation)\" of the Chinese room argument, because these arguments actually imply that no digital computers can have a mind.",
"title": "Computer science"
},
{
"paragraph_id": 46,
"text": "There are some critics, such as Hanoch Ben-Yami, who argue that the Chinese room cannot simulate all the abilities of a digital computer, such as being able to determine the current time.",
"title": "Computer science"
},
{
"paragraph_id": 47,
"text": "Searle has produced a more formal version of the argument of which the Chinese Room forms a part. He presented the first version in 1984. The version given below is from 1990. The Chinese room thought experiment is intended to prove point A3.",
"title": "Complete argument"
},
{
"paragraph_id": 48,
"text": "He begins with three axioms:",
"title": "Complete argument"
},
{
"paragraph_id": 49,
"text": "Searle posits that these lead directly to this conclusion:",
"title": "Complete argument"
},
{
"paragraph_id": 50,
"text": "This much of the argument is intended to show that artificial intelligence can never produce a machine with a mind by writing programs that manipulate symbols. The remainder of the argument addresses a different issue. Is the human brain running a program? In other words, is the computational theory of mind correct? He begins with an axiom that is intended to express the basic modern scientific consensus about brains and minds:",
"title": "Complete argument"
},
{
"paragraph_id": 51,
"text": "Searle claims that we can derive \"immediately\" and \"trivially\" that:",
"title": "Complete argument"
},
{
"paragraph_id": 52,
"text": "And from this he derives the further conclusions:",
"title": "Complete argument"
},
{
"paragraph_id": 53,
"text": "Refutations of Searle's argument take many different forms (see below). Computationalists and functionalists reject A3, arguing that \"syntax\" (as Searle describes it) can have \"semantics\" if the syntax has the right functional structure. Eliminative materialists reject A2, arguing that minds don't actually have \"semantics\" -- that thoughts and other mental phenomena are inherently meaningless but nevertheless function as if they had meaning.",
"title": "Complete argument"
},
{
"paragraph_id": 54,
"text": "Replies to Searle's argument may be classified according to what they claim to show:",
"title": "Replies"
},
{
"paragraph_id": 55,
"text": "Some of the arguments (robot and brain simulation, for example) fall into multiple categories.",
"title": "Replies"
},
{
"paragraph_id": 56,
"text": "These replies attempt to answer the question: since the man in the room does not speak Chinese, where is the \"mind\" that does? These replies address the key ontological issues of mind vs. body and simulation vs. reality. All of the replies that identify the mind in the room are versions of \"the system reply\".",
"title": "Replies"
},
{
"paragraph_id": 57,
"text": "More sophisticated versions of the systems reply try to identify more precisely what \"the system\" is and they differ in exactly how they describe it. According to these replies, the \"mind that speaks Chinese\" could be such things as: the \"software\", a \"program\", a \"running program\", a simulation of the \"neural correlates of consciousness\", the \"functional system\", a \"simulated mind\", an \"emergent property\", or \"a virtual mind\" (described below).",
"title": "Replies"
},
{
"paragraph_id": 58,
"text": "These replies provide an explanation of exactly who it is that understands Chinese. If there is something besides the man in the room that can understand Chinese, Searle cannot argue that (1) the man does not understand Chinese, therefore (2) nothing in the room understands Chinese. This, according to those who make this reply, shows that Searle's argument fails to prove that \"strong AI\" is false.",
"title": "Replies"
},
{
"paragraph_id": 59,
"text": "These replies, by themselves, do not provide any evidence that strong AI is true, however. They do not show that the system (or the virtual mind) understands Chinese, other than the hypothetical premise that it passes the Turing Test. Searle argues that, if we are to consider Strong AI remotely plausible, the Chinese Room is an example that requires explanation, and it is difficult or impossible to explain how consciousness might \"emerge\" from the room or how the system would have consciousness. As Searle writes \"the systems reply simply begs the question by insisting that the system must understand Chinese\" and thus is dodging the question or hopelessly circular.",
"title": "Replies"
},
{
"paragraph_id": 60,
"text": "As far as the person in the room is concerned, the symbols are just meaningless \"squiggles.\" But if the Chinese room really \"understands\" what it is saying, then the symbols must get their meaning from somewhere. These arguments attempt to connect the symbols to the things they symbolize. These replies address Searle's concerns about intentionality, symbol grounding and syntax vs. semantics.",
"title": "Replies"
},
{
"paragraph_id": 61,
"text": "To each of these suggestions, Searle's response is the same: no matter how much knowledge is written into the program and no matter how the program is connected to the world, he is still in the room manipulating symbols according to rules. His actions are syntactic and this can never explain to him what the symbols stand for. Searle writes \"syntax is insufficient for semantics.\"",
"title": "Replies"
},
{
"paragraph_id": 62,
"text": "However, for those who accept that Searle's actions simulate a mind, separate from his own, the important question is not what the symbols mean to Searle, what is important is what they mean to the virtual mind. While Searle is trapped in the room, the virtual mind is not: it is connected to the outside world through the Chinese speakers it speaks to, through the programmers who gave it world knowledge, and through the cameras and other sensors that roboticists can supply.",
"title": "Replies"
},
{
"paragraph_id": 63,
"text": "These arguments are all versions of the systems reply that identify a particular kind of system as being important; they identify some special technology that would create conscious understanding in a machine. (The \"robot\" and \"commonsense knowledge\" replies above also specify a certain kind of system as being important.)",
"title": "Replies"
},
{
"paragraph_id": 64,
"text": "[I]magine that instead of a monolingual man in a room shuffling symbols we have the man operate an elaborate set of water pipes with valves connecting them. When the man receives the Chinese symbols, he looks up in the program, written in English, which valves he has to turn on and off. Each water connection corresponds to a synapse in the Chinese brain, and the whole system is rigged up so that after doing all the right firings, that is after turning on all the right faucets, the Chinese answers pop out at the output end of the series of pipes. Now where is the understanding in this system? It takes Chinese as input, it simulates the formal structure of the synapses of the Chinese brain, and it gives Chinese as output. But the man certainly doesn't understand Chinese, and neither do the water pipes, and if we are tempted to adopt what I think is the absurd view that somehow the conjunction of man and water pipes understands, remember that in principle the man can internalize the formal structure of the water pipes and do all the \"neuron firings\" in his imagination.",
"title": "Replies"
},
{
"paragraph_id": 65,
"text": "Two variations on the brain simulator reply are the China brain and the brain-replacement scenario.",
"title": "Replies"
},
{
"paragraph_id": 66,
"text": "These arguments (and the robot or commonsense knowledge replies) identify some special technology that would help create conscious understanding in a machine. They may be interpreted in two ways: either they claim (1) this technology is required for consciousness, the Chinese room does not or cannot implement this technology, and therefore the Chinese room cannot pass the Turing test or (even if it did) it would not have conscious understanding. Or they may be claiming that (2) it is easier to see that the Chinese room has a mind if we visualize this technology as being used to create it.",
"title": "Replies"
},
{
"paragraph_id": 67,
"text": "In the first case, where features like a robot body or a connectionist architecture are required, Searle claims that strong AI (as he understands it) has been abandoned. The Chinese room has all the elements of a Turing complete machine, and thus is capable of simulating any digital computation whatsoever. If Searle's room cannot pass the Turing test then there is no other digital technology that could pass the Turing test. If Searle's room could pass the Turing test, but still does not have a mind, then the Turing test is not sufficient to determine if the room has a \"mind\". Either way, it denies one or the other of the positions Searle thinks of as \"strong AI\", proving his argument.",
"title": "Replies"
},
{
"paragraph_id": 68,
"text": "The brain arguments in particular deny strong AI if they assume that there is no simpler way to describe the mind than to create a program that is just as mysterious as the brain was. He writes \"I thought the whole idea of strong AI was that we don't need to know how the brain works to know how the mind works.\" If computation does not provide an explanation of the human mind, then strong AI has failed, according to Searle.",
"title": "Replies"
},
{
"paragraph_id": 69,
"text": "Other critics hold that the room as Searle described it does, in fact, have a mind, however they argue that it is difficult to see—Searle's description is correct, but misleading. By redesigning the room more realistically they hope to make this more obvious. In this case, these arguments are being used as appeals to intuition (see next section).",
"title": "Replies"
},
{
"paragraph_id": 70,
"text": "In fact, the room can just as easily be redesigned to weaken our intuitions. Ned Block's Blockhead argument suggests that the program could, in theory, be rewritten into a simple lookup table of rules of the form \"if the user writes S, reply with P and goto X\". At least in principle, any program can be rewritten (or \"refactored\") into this form, even a brain simulation. In the blockhead scenario, the entire mental state is hidden in the letter X, which represents a memory address—a number associated with the next rule. It is hard to visualize that an instant of one's conscious experience can be captured in a single large number, yet this is exactly what \"strong AI\" claims. On the other hand, such a lookup table would be ridiculously large (to the point of being physically impossible), and the states could therefore be extremely specific.",
"title": "Replies"
},
{
"paragraph_id": 71,
"text": "Searle argues that however the program is written or however the machine is connected to the world, the mind is being simulated by a simple step-by-step digital machine (or machines). These machines are always just like the man in the room: they understand nothing and do not speak Chinese. They are merely manipulating symbols without knowing what they mean. Searle writes: \"I can have any formal program you like, but I still understand nothing.\"",
"title": "Replies"
},
{
"paragraph_id": 72,
"text": "The following arguments (and the intuitive interpretations of the arguments above) do not directly explain how a Chinese speaking mind could exist in Searle's room, or how the symbols he manipulates could become meaningful. However, by raising doubts about Searle's intuitions they support other positions, such as the system and robot replies. These arguments, if accepted, prevent Searle from claiming that his conclusion is obvious by undermining the intuitions that his certainty requires.",
"title": "Replies"
},
{
"paragraph_id": 73,
"text": "Several critics believe that Searle's argument relies entirely on intuitions. Ned Block writes \"Searle's argument depends for its force on intuitions that certain entities do not think.\" Daniel Dennett describes the Chinese room argument as a misleading \"intuition pump\" and writes \"Searle's thought experiment depends, illicitly, on your imagining too simple a case, an irrelevant case, and drawing the 'obvious' conclusion from it.\"",
"title": "Replies"
},
{
"paragraph_id": 74,
"text": "Some of the arguments above also function as appeals to intuition, especially those that are intended to make it seem more plausible that the Chinese room contains a mind, which can include the robot, commonsense knowledge, brain simulation and connectionist replies. Several of the replies above also address the specific issue of complexity. The connectionist reply emphasizes that a working artificial intelligence system would have to be as complex and as interconnected as the human brain. The commonsense knowledge reply emphasizes that any program that passed a Turing test would have to be \"an extraordinarily supple, sophisticated, and multilayered system, brimming with 'world knowledge' and meta-knowledge and meta-meta-knowledge\", as Daniel Dennett explains.",
"title": "Replies"
},
{
"paragraph_id": 75,
"text": "Searle argues that his critics are also relying on intuitions, however his opponents' intuitions have no empirical basis. He writes that, in order to consider the \"system reply\" as remotely plausible, a person must be \"under the grip of an ideology\". The system reply only makes sense (to Searle) if one assumes that any \"system\" can have consciousness, just by virtue of being a system with the right behavior and functional parts. This assumption, he argues, is not tenable given our experience of consciousness.",
"title": "Replies"
},
{
"paragraph_id": 76,
"text": "Several replies argue that Searle's argument is irrelevant because his assumptions about the mind and consciousness are faulty. Searle believes that human beings directly experience their consciousness, intentionality and the nature of the mind every day, and that this experience of consciousness is not open to question. He writes that we must \"presuppose the reality and knowability of the mental.\" The replies below question whether Searle is justified in using his own experience of consciousness to determine that it is more than mechanical symbol processing. In particular, the other minds reply argues that we cannot use our experience of consciousness to answer questions about other minds (even the mind of a computer), the epiphenoma replies question whether we can make any argument at all about something like consciousness which can not, by definition, be detected by any experiment, and the eliminative materialist reply argues that Searle's own personal consciousness does not \"exist\" in the sense that Searle thinks it does,",
"title": "Replies"
},
{
"paragraph_id": 77,
"text": "Searle disagrees with this analysis and argues that \"the study of the mind starts with such facts as that humans have beliefs, while thermostats, telephones, and adding machines don't ... what we wanted to know is what distinguishes the mind from thermostats and livers.\" He takes it as obvious that we can detect the presence of consciousness and dismisses these replies as being off the point.",
"title": "Replies"
},
{
"paragraph_id": 78,
"text": "Margaret Boden argued in her paper \"Escaping from the Chinese Room\" that even if the person in the room does not understand the Chinese, it does not mean there is no understanding in the room. The person in the room at least understands the rule book used to provide output responses.",
"title": "Replies"
},
{
"paragraph_id": 79,
"text": "The Chinese room argument is a central concept in Peter Watts's novels Blindsight and (to a lesser extent) Echopraxia. Greg Egan illustrates the concept succinctly (and somewhat horrifically) in his 1990 short story Learning to Be Me, in his collection Axiomatic.",
"title": "In popular culture"
},
{
"paragraph_id": 80,
"text": "It is a central theme in the video game Zero Escape: Virtue's Last Reward, and ties into the game's narrative.",
"title": "In popular culture"
},
{
"paragraph_id": 81,
"text": "A similar human computer is imagined in Liu Cixin's novel The Three-Body Problem, described thus by Philip Steiner: \"a massive human-computer by instrumentalizing millions of soldiers [who] take the role of signal input and signal output and are instructed to perform different logical circuits, like an AND gate and an OR gate\".",
"title": "In popular culture"
}
] | The Chinese room argument holds that a digital computer executing a program cannot have a "mind", "understanding", or "consciousness", regardless of how intelligently or human-like the program may make the computer behave. The argument was presented by philosopher John Searle in his paper "Minds, Brains, and Programs", published in Behavioral and Brain Sciences in 1980. Similar arguments were presented by Gottfried Leibniz (1714), Anatoly Dneprov (1961), Lawrence Davis (1974) and Ned Block (1978). Searle's version has been widely discussed in the years since. The centerpiece of Searle's argument is a thought experiment known as the Chinese room. The argument is directed against the philosophical positions of functionalism and computationalism which hold that the mind may be viewed as an information-processing system operating on formal symbols, and that simulation of a given mental state is sufficient for its presence. Specifically, the argument is intended to refute a position Searle calls the strong AI hypothesis: "The appropriately programmed computer with the right inputs and outputs would thereby have a mind in exactly the same sense human beings have minds." Although it was originally presented in reaction to the statements of artificial intelligence (AI) researchers, it is not an argument against the goals of mainstream AI research because it does not show a limit in the amount of "intelligent" behavior a machine can display. The argument applies only to digital computers running programs and does not apply to machines in general. | 2001-08-28T04:17:13Z | 2023-12-24T11:21:17Z | [
"Template:Short description",
"Template:Reflist",
"Template:Cite IEP",
"Template:Blockquote",
"Template:Harvnb",
"Template:Refend",
"Template:Webarchive",
"Template:OCLC",
"Template:Efn",
"Template:Sfn",
"Template:ISBN",
"Template:See also",
"Template:Cite journal",
"Template:Wikibooks",
"Template:Cite arXiv",
"Template:Quote",
"Template:Who",
"Template:Refbegin",
"Template:Notelist",
"Template:Cite web",
"Template:Searle 1980",
"Template:For",
"Template:Artificial intelligence",
"Template:Main",
"Template:Citation",
"Template:Crevier 1993",
"Template:Harvtxt",
"Template:Turing 1950",
"Template:Philosophy of mind",
"Template:Use mdy dates",
"Template:Citation needed",
"Template:Cite book",
"Template:Authority control"
] | https://en.wikipedia.org/wiki/Chinese_room |
6,217 | Charon (disambiguation) | Charon, in Greek mythology, is the ferryman who carried the souls of the dead to the underworld.
Charon may also refer to: | [
{
"paragraph_id": 0,
"text": "Charon, in Greek mythology, is the ferryman who carried the souls of the dead to the underworld.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Charon may also refer to:",
"title": ""
}
] | Charon, in Greek mythology, is the ferryman who carried the souls of the dead to the underworld. Charon may also refer to: | 2001-08-28T01:53:43Z | 2023-12-08T05:40:16Z | [
"Template:Wiktionary",
"Template:TOC right",
"Template:Disambiguation"
] | https://en.wikipedia.org/wiki/Charon_(disambiguation) |
6,220 | Circle | A circle is a shape consisting of all points in a plane that are at a given distance from a given point, the centre. The distance between any point of the circle and the centre is called the radius.
The circle has been known since before the beginning of recorded history. Natural circles are common, such as the full moon or a slice of round fruit. The circle is the basis for the wheel, which, with related inventions such as gears, makes much of modern machinery possible. In mathematics, the study of the circle has helped inspire the development of geometry, astronomy and calculus.
All of the specified regions may be considered as open, that is, not containing their boundaries, or as closed, including their respective boundaries.
The word circle derives from the Greek κίρκος/κύκλος (kirkos/kuklos), itself a metathesis of the Homeric Greek κρίκος (krikos), meaning "hoop" or "ring". The origins of the words circus and circuit are closely related.
Prehistoric people made stone circles and timber circles, and circular elements are common in petroglyphs and cave paintings. Disc-shaped prehistoric artifacts include the Nebra sky disc and jade discs called Bi.
The Egyptian Rhind papyrus, dated to 1700 BCE, gives a method to find the area of a circle. The result corresponds to 256/81 (3.16049...) as an approximate value of π.
Book 3 of Euclid's Elements deals with the properties of circles. Euclid's definition of a circle is:
A circle is a plane figure bounded by one curved line, and such that all straight lines drawn from a certain point within it to the bounding line, are equal. The bounding line is called its circumference and the point, its centre.
In Plato's Seventh Letter there is a detailed definition and explanation of the circle. Plato explains the perfect circle, and how it is different from any drawing, words, definition or explanation. Early science, particularly geometry and astrology and astronomy, was connected to the divine for most medieval scholars, and many believed that there was something intrinsically "divine" or "perfect" that could be found in circles.
In 1880 CE, Ferdinand von Lindemann proved that π is transcendental, proving that the millennia-old problem of squaring the circle cannot be performed with straightedge and compass.
From the time of the earliest known civilisations – such as the Assyrians and ancient Egyptians, those in the Indus Valley and along the Yellow River in China, and the Western civilisations of ancient Greece and Rome during classical Antiquity – the circle has been used directly or indirectly in visual art to convey the artist's message and to express certain ideas. However, differences in worldview (beliefs and culture) had a great impact on artists' perceptions. While some emphasised the circle's perimeter to demonstrate their democratic manifestation, others focused on its centre to symbolise the concept of cosmic unity. In mystical doctrines, the circle mainly symbolises the infinite and cyclical nature of existence, but in religious traditions it represents heavenly bodies and divine spirits.
The circle signifies many sacred and spiritual concepts, including unity, infinity, wholeness, the universe, divinity, balance, stability and perfection, among others. Such concepts have been conveyed in cultures worldwide through the use of symbols, for example, a compass, a halo, the vesica piscis and its derivatives (fish, eye, aureole, mandorla, etc.), the ouroboros, the Dharma wheel, a rainbow, mandalas, rose windows and so forth. Magic circles are part of some traditions of Western esotericism.
The ratio of a circle's circumference to its diameter is π (pi), an irrational constant approximately equal to 3.141592654. Thus the circumference C is related to the radius r and diameter d by:
As proved by Archimedes, in his Measurement of a Circle, the area enclosed by a circle is equal to that of a triangle whose base has the length of the circle's circumference and whose height equals the circle's radius, which comes to π multiplied by the radius squared:
Equivalently, denoting diameter by d,
that is, approximately 79% of the circumscribing square (whose side is of length d).
The circle is the plane curve enclosing the maximum area for a given arc length. This relates the circle to a problem in the calculus of variations, namely the isoperimetric inequality.
In an x–y Cartesian coordinate system, the circle with centre coordinates (a, b) and radius r is the set of all points (x, y) such that
This equation, known as the equation of the circle, follows from the Pythagorean theorem applied to any point on the circle: as shown in the adjacent diagram, the radius is the hypotenuse of a right-angled triangle whose other sides are of length |x − a| and |y − b|. If the circle is centred at the origin (0, 0), then the equation simplifies to
The equation can be written in parametric form using the trigonometric functions sine and cosine as
where t is a parametric variable in the range 0 to 2π, interpreted geometrically as the angle that the ray from (a, b) to (x, y) makes with the positive x axis.
An alternative parametrisation of the circle is
In this parameterisation, the ratio of t to r can be interpreted geometrically as the stereographic projection of the line passing through the centre parallel to the x axis (see Tangent half-angle substitution). However, this parameterisation works only if t is made to range not only through all reals but also to a point at infinity; otherwise, the leftmost point of the circle would be omitted.
The equation of the circle determined by three points ( x 1 , y 1 ) , ( x 2 , y 2 ) , ( x 3 , y 3 ) {\displaystyle (x_{1},y_{1}),(x_{2},y_{2}),(x_{3},y_{3})} not on a line is obtained by a conversion of the 3-point form of a circle equation:
In homogeneous coordinates, each conic section with the equation of a circle has the form
It can be proven that a conic section is a circle exactly when it contains (when extended to the complex projective plane) the points I(1: i: 0) and J(1: −i: 0). These points are called the circular points at infinity.
In polar coordinates, the equation of a circle is
where a is the radius of the circle, ( r , θ ) {\displaystyle (r,\theta )} are the polar coordinates of a generic point on the circle, and ( r 0 , ϕ ) {\displaystyle (r_{0},\phi )} are the polar coordinates of the centre of the circle (i.e., r0 is the distance from the origin to the centre of the circle, and φ is the anticlockwise angle from the positive x axis to the line connecting the origin to the centre of the circle). For a circle centred on the origin, i.e. r0 = 0, this reduces to r = a. When r0 = a, or when the origin lies on the circle, the equation becomes
In the general case, the equation can be solved for r, giving
Without the ± sign, the equation would in some cases describe only half a circle.
In the complex plane, a circle with a centre at c and radius r has the equation
In parametric form, this can be written as
The slightly generalised equation
for real p, q and complex g is sometimes called a generalised circle. This becomes the above equation for a circle with p = 1 , g = − c ¯ , q = r 2 − | c | 2 {\displaystyle p=1,\ g=-{\overline {c}},\ q=r^{2}-|c|^{2}} , since | z − c | 2 = z z ¯ − c ¯ z − c z ¯ + c c ¯ {\displaystyle |z-c|^{2}=z{\overline {z}}-{\overline {c}}z-c{\overline {z}}+c{\overline {c}}} . Not all generalised circles are actually circles: a generalised circle is either a (true) circle or a line.
The tangent line through a point P on the circle is perpendicular to the diameter passing through P. If P = (x1, y1) and the circle has centre (a, b) and radius r, then the tangent line is perpendicular to the line from (a, b) to (x1, y1), so it has the form (x1 − a)x + (y1 – b)y = c. Evaluating at (x1, y1) determines the value of c, and the result is that the equation of the tangent is
or
If y1 ≠ b, then the slope of this line is
This can also be found using implicit differentiation.
When the centre of the circle is at the origin, then the equation of the tangent line becomes
and its slope is
An inscribed angle (examples are the blue and green angles in the figure) is exactly half the corresponding central angle (red). Hence, all inscribed angles that subtend the same arc (pink) are equal. Angles inscribed on the arc (brown) are supplementary. In particular, every inscribed angle that subtends a diameter is a right angle (since the central angle is 180°).
The sagitta (also known as the versine) is a line segment drawn perpendicular to a chord, between the midpoint of that chord and the arc of the circle.
Given the length y of a chord and the length x of the sagitta, the Pythagorean theorem can be used to calculate the radius of the unique circle that will fit around the two lines:
Another proof of this result, which relies only on two chord properties given above, is as follows. Given a chord of length y and with sagitta of length x, since the sagitta intersects the midpoint of the chord, we know that it is a part of a diameter of the circle. Since the diameter is twice the radius, the "missing" part of the diameter is (2r − x) in length. Using the fact that one part of one chord times the other part is equal to the same product taken along a chord intersecting the first chord, we find that (2r − x)x = (y / 2). Solving for r, we find the required result.
There are many compass-and-straightedge constructions resulting in circles.
The simplest and most basic is the construction given the centre of the circle and a point on the circle. Place the fixed leg of the compass on the centre point, the movable leg on the point on the circle and rotate the compass.
Apollonius of Perga showed that a circle may also be defined as the set of points in a plane having a constant ratio (other than 1) of distances to two fixed foci, A and B. (The set of points where the distances are equal is the perpendicular bisector of segment AB, a line.) That circle is sometimes said to be drawn about two points.
The proof is in two parts. First, one must prove that, given two foci A and B and a ratio of distances, any point P satisfying the ratio of distances must fall on a particular circle. Let C be another point, also satisfying the ratio and lying on segment AB. By the angle bisector theorem the line segment PC will bisect the interior angle APB, since the segments are similar:
Analogously, a line segment PD through some point D on AB extended bisects the corresponding exterior angle BPQ where Q is on AP extended. Since the interior and exterior angles sum to 180 degrees, the angle CPD is exactly 90 degrees; that is, a right angle. The set of points P such that angle CPD is a right angle forms a circle, of which CD is a diameter.
Second, see for a proof that every point on the indicated circle satisfies the given ratio.
A closely related property of circles involves the geometry of the cross-ratio of points in the complex plane. If A, B, and C are as above, then the circle of Apollonius for these three points is the collection of points P for which the absolute value of the cross-ratio is equal to one:
Stated another way, P is a point on the circle of Apollonius if and only if the cross-ratio [A, B; C, P] is on the unit circle in the complex plane.
If C is the midpoint of the segment AB, then the collection of points P satisfying the Apollonius condition
is not a circle, but rather a line.
Thus, if A, B, and C are given distinct points in the plane, then the locus of points P satisfying the above equation is called a "generalised circle." It may either be a true circle or a line. In this sense a line is a generalised circle of infinite radius.
In every triangle a unique circle, called the incircle, can be inscribed such that it is tangent to each of the three sides of the triangle.
About every triangle a unique circle, called the circumcircle, can be circumscribed such that it goes through each of the triangle's three vertices.
A tangential polygon, such as a tangential quadrilateral, is any convex polygon within which a circle can be inscribed that is tangent to each side of the polygon. Every regular polygon and every triangle is a tangential polygon.
A cyclic polygon is any convex polygon about which a circle can be circumscribed, passing through each vertex. A well-studied example is the cyclic quadrilateral. Every regular polygon and every triangle is a cyclic polygon. A polygon that is both cyclic and tangential is called a bicentric polygon.
A hypocycloid is a curve that is inscribed in a given circle by tracing a fixed point on a smaller circle that rolls within and tangent to the given circle.
The circle can be viewed as a limiting case of various other figures:
Consider a finite set of n {\displaystyle n} points in the plane. The locus of points such that the sum of the squares of the distances to the given points is constant is a circle, whose centre is at the centroid of the given points. A generalization for higher powers of distances is obtained if under n {\displaystyle n} points the vertices of the regular polygon P n {\displaystyle P_{n}} are taken. The locus of points such that the sum of the 2 m {\displaystyle 2m} -th power of distances d i {\displaystyle d_{i}} to the vertices of a given regular polygon with circumradius R {\displaystyle R} is constant is a circle, if
whose centre is the centroid of the P n {\displaystyle P_{n}} .
In the case of the equilateral triangle, the loci of the constant sums of the second and fourth powers are circles, whereas for the square, the loci are circles for the constant sums of the second, fourth, and sixth powers. For the regular pentagon the constant sum of the eighth powers of the distances will be added and so forth.
Squaring the circle is the problem, proposed by ancient geometers, of constructing a square with the same area as a given circle by using only a finite number of steps with compass and straightedge.
In 1882, the task was proven to be impossible, as a consequence of the Lindemann–Weierstrass theorem, which proves that pi (π) is a transcendental number, rather than an algebraic irrational number; that is, it is not the root of any polynomial with rational coefficients. Despite the impossibility, this topic continues to be of interest for pseudomath enthusiasts.
Defining a circle as the set of points with a fixed distance from a point, different shapes can be considered circles under different definitions of distance. In p-norm, distance is determined by
In Euclidean geometry, p = 2, giving the familiar
In taxicab geometry, p = 1. Taxicab circles are squares with sides oriented at a 45° angle to the coordinate axes. While each side would have length 2 r {\displaystyle {\sqrt {2}}r} using a Euclidean metric, where r is the circle's radius, its length in taxicab geometry is 2r. Thus, a circle's circumference is 8r. Thus, the value of a geometric analog to π {\displaystyle \pi } is 4 in this geometry. The formula for the unit circle in taxicab geometry is | x | + | y | = 1 {\displaystyle |x|+|y|=1} in Cartesian coordinates and
in polar coordinates.
A circle of radius 1 (using this distance) is the von Neumann neighborhood of its centre.
A circle of radius r for the Chebyshev distance (L∞ metric) on a plane is also a square with side length 2r parallel to the coordinate axes, so planar Chebyshev distance can be viewed as equivalent by rotation and scaling to planar taxicab distance. However, this equivalence between L1 and L∞ metrics does not generalize to higher dimensions.
The circle is the one-dimensional hypersphere (the 1-sphere).
In topology, a circle is not limited to the geometric concept, but to all of its homeomorphisms. Two topological circles are equivalent if one can be transformed into the other via a deformation of R upon itself (known as an ambient isotopy). | [
{
"paragraph_id": 0,
"text": "A circle is a shape consisting of all points in a plane that are at a given distance from a given point, the centre. The distance between any point of the circle and the centre is called the radius.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The circle has been known since before the beginning of recorded history. Natural circles are common, such as the full moon or a slice of round fruit. The circle is the basis for the wheel, which, with related inventions such as gears, makes much of modern machinery possible. In mathematics, the study of the circle has helped inspire the development of geometry, astronomy and calculus.",
"title": ""
},
{
"paragraph_id": 2,
"text": "All of the specified regions may be considered as open, that is, not containing their boundaries, or as closed, including their respective boundaries.",
"title": "Terminology"
},
{
"paragraph_id": 3,
"text": "The word circle derives from the Greek κίρκος/κύκλος (kirkos/kuklos), itself a metathesis of the Homeric Greek κρίκος (krikos), meaning \"hoop\" or \"ring\". The origins of the words circus and circuit are closely related.",
"title": "Etymology"
},
{
"paragraph_id": 4,
"text": "Prehistoric people made stone circles and timber circles, and circular elements are common in petroglyphs and cave paintings. Disc-shaped prehistoric artifacts include the Nebra sky disc and jade discs called Bi.",
"title": "History"
},
{
"paragraph_id": 5,
"text": "The Egyptian Rhind papyrus, dated to 1700 BCE, gives a method to find the area of a circle. The result corresponds to 256/81 (3.16049...) as an approximate value of π.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "Book 3 of Euclid's Elements deals with the properties of circles. Euclid's definition of a circle is:",
"title": "History"
},
{
"paragraph_id": 7,
"text": "A circle is a plane figure bounded by one curved line, and such that all straight lines drawn from a certain point within it to the bounding line, are equal. The bounding line is called its circumference and the point, its centre.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "In Plato's Seventh Letter there is a detailed definition and explanation of the circle. Plato explains the perfect circle, and how it is different from any drawing, words, definition or explanation. Early science, particularly geometry and astrology and astronomy, was connected to the divine for most medieval scholars, and many believed that there was something intrinsically \"divine\" or \"perfect\" that could be found in circles.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "In 1880 CE, Ferdinand von Lindemann proved that π is transcendental, proving that the millennia-old problem of squaring the circle cannot be performed with straightedge and compass.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "From the time of the earliest known civilisations – such as the Assyrians and ancient Egyptians, those in the Indus Valley and along the Yellow River in China, and the Western civilisations of ancient Greece and Rome during classical Antiquity – the circle has been used directly or indirectly in visual art to convey the artist's message and to express certain ideas. However, differences in worldview (beliefs and culture) had a great impact on artists' perceptions. While some emphasised the circle's perimeter to demonstrate their democratic manifestation, others focused on its centre to symbolise the concept of cosmic unity. In mystical doctrines, the circle mainly symbolises the infinite and cyclical nature of existence, but in religious traditions it represents heavenly bodies and divine spirits.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "The circle signifies many sacred and spiritual concepts, including unity, infinity, wholeness, the universe, divinity, balance, stability and perfection, among others. Such concepts have been conveyed in cultures worldwide through the use of symbols, for example, a compass, a halo, the vesica piscis and its derivatives (fish, eye, aureole, mandorla, etc.), the ouroboros, the Dharma wheel, a rainbow, mandalas, rose windows and so forth. Magic circles are part of some traditions of Western esotericism.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "The ratio of a circle's circumference to its diameter is π (pi), an irrational constant approximately equal to 3.141592654. Thus the circumference C is related to the radius r and diameter d by:",
"title": "Analytic results"
},
{
"paragraph_id": 13,
"text": "As proved by Archimedes, in his Measurement of a Circle, the area enclosed by a circle is equal to that of a triangle whose base has the length of the circle's circumference and whose height equals the circle's radius, which comes to π multiplied by the radius squared:",
"title": "Analytic results"
},
{
"paragraph_id": 14,
"text": "Equivalently, denoting diameter by d,",
"title": "Analytic results"
},
{
"paragraph_id": 15,
"text": "that is, approximately 79% of the circumscribing square (whose side is of length d).",
"title": "Analytic results"
},
{
"paragraph_id": 16,
"text": "The circle is the plane curve enclosing the maximum area for a given arc length. This relates the circle to a problem in the calculus of variations, namely the isoperimetric inequality.",
"title": "Analytic results"
},
{
"paragraph_id": 17,
"text": "In an x–y Cartesian coordinate system, the circle with centre coordinates (a, b) and radius r is the set of all points (x, y) such that",
"title": "Analytic results"
},
{
"paragraph_id": 18,
"text": "This equation, known as the equation of the circle, follows from the Pythagorean theorem applied to any point on the circle: as shown in the adjacent diagram, the radius is the hypotenuse of a right-angled triangle whose other sides are of length |x − a| and |y − b|. If the circle is centred at the origin (0, 0), then the equation simplifies to",
"title": "Analytic results"
},
{
"paragraph_id": 19,
"text": "The equation can be written in parametric form using the trigonometric functions sine and cosine as",
"title": "Analytic results"
},
{
"paragraph_id": 20,
"text": "where t is a parametric variable in the range 0 to 2π, interpreted geometrically as the angle that the ray from (a, b) to (x, y) makes with the positive x axis.",
"title": "Analytic results"
},
{
"paragraph_id": 21,
"text": "An alternative parametrisation of the circle is",
"title": "Analytic results"
},
{
"paragraph_id": 22,
"text": "In this parameterisation, the ratio of t to r can be interpreted geometrically as the stereographic projection of the line passing through the centre parallel to the x axis (see Tangent half-angle substitution). However, this parameterisation works only if t is made to range not only through all reals but also to a point at infinity; otherwise, the leftmost point of the circle would be omitted.",
"title": "Analytic results"
},
{
"paragraph_id": 23,
"text": "The equation of the circle determined by three points ( x 1 , y 1 ) , ( x 2 , y 2 ) , ( x 3 , y 3 ) {\\displaystyle (x_{1},y_{1}),(x_{2},y_{2}),(x_{3},y_{3})} not on a line is obtained by a conversion of the 3-point form of a circle equation:",
"title": "Analytic results"
},
{
"paragraph_id": 24,
"text": "In homogeneous coordinates, each conic section with the equation of a circle has the form",
"title": "Analytic results"
},
{
"paragraph_id": 25,
"text": "It can be proven that a conic section is a circle exactly when it contains (when extended to the complex projective plane) the points I(1: i: 0) and J(1: −i: 0). These points are called the circular points at infinity.",
"title": "Analytic results"
},
{
"paragraph_id": 26,
"text": "In polar coordinates, the equation of a circle is",
"title": "Analytic results"
},
{
"paragraph_id": 27,
"text": "where a is the radius of the circle, ( r , θ ) {\\displaystyle (r,\\theta )} are the polar coordinates of a generic point on the circle, and ( r 0 , ϕ ) {\\displaystyle (r_{0},\\phi )} are the polar coordinates of the centre of the circle (i.e., r0 is the distance from the origin to the centre of the circle, and φ is the anticlockwise angle from the positive x axis to the line connecting the origin to the centre of the circle). For a circle centred on the origin, i.e. r0 = 0, this reduces to r = a. When r0 = a, or when the origin lies on the circle, the equation becomes",
"title": "Analytic results"
},
{
"paragraph_id": 28,
"text": "In the general case, the equation can be solved for r, giving",
"title": "Analytic results"
},
{
"paragraph_id": 29,
"text": "Without the ± sign, the equation would in some cases describe only half a circle.",
"title": "Analytic results"
},
{
"paragraph_id": 30,
"text": "In the complex plane, a circle with a centre at c and radius r has the equation",
"title": "Analytic results"
},
{
"paragraph_id": 31,
"text": "In parametric form, this can be written as",
"title": "Analytic results"
},
{
"paragraph_id": 32,
"text": "The slightly generalised equation",
"title": "Analytic results"
},
{
"paragraph_id": 33,
"text": "for real p, q and complex g is sometimes called a generalised circle. This becomes the above equation for a circle with p = 1 , g = − c ¯ , q = r 2 − | c | 2 {\\displaystyle p=1,\\ g=-{\\overline {c}},\\ q=r^{2}-|c|^{2}} , since | z − c | 2 = z z ¯ − c ¯ z − c z ¯ + c c ¯ {\\displaystyle |z-c|^{2}=z{\\overline {z}}-{\\overline {c}}z-c{\\overline {z}}+c{\\overline {c}}} . Not all generalised circles are actually circles: a generalised circle is either a (true) circle or a line.",
"title": "Analytic results"
},
{
"paragraph_id": 34,
"text": "The tangent line through a point P on the circle is perpendicular to the diameter passing through P. If P = (x1, y1) and the circle has centre (a, b) and radius r, then the tangent line is perpendicular to the line from (a, b) to (x1, y1), so it has the form (x1 − a)x + (y1 – b)y = c. Evaluating at (x1, y1) determines the value of c, and the result is that the equation of the tangent is",
"title": "Analytic results"
},
{
"paragraph_id": 35,
"text": "or",
"title": "Analytic results"
},
{
"paragraph_id": 36,
"text": "If y1 ≠ b, then the slope of this line is",
"title": "Analytic results"
},
{
"paragraph_id": 37,
"text": "This can also be found using implicit differentiation.",
"title": "Analytic results"
},
{
"paragraph_id": 38,
"text": "When the centre of the circle is at the origin, then the equation of the tangent line becomes",
"title": "Analytic results"
},
{
"paragraph_id": 39,
"text": "and its slope is",
"title": "Analytic results"
},
{
"paragraph_id": 40,
"text": "An inscribed angle (examples are the blue and green angles in the figure) is exactly half the corresponding central angle (red). Hence, all inscribed angles that subtend the same arc (pink) are equal. Angles inscribed on the arc (brown) are supplementary. In particular, every inscribed angle that subtends a diameter is a right angle (since the central angle is 180°).",
"title": "Properties"
},
{
"paragraph_id": 41,
"text": "The sagitta (also known as the versine) is a line segment drawn perpendicular to a chord, between the midpoint of that chord and the arc of the circle.",
"title": "Properties"
},
{
"paragraph_id": 42,
"text": "Given the length y of a chord and the length x of the sagitta, the Pythagorean theorem can be used to calculate the radius of the unique circle that will fit around the two lines:",
"title": "Properties"
},
{
"paragraph_id": 43,
"text": "Another proof of this result, which relies only on two chord properties given above, is as follows. Given a chord of length y and with sagitta of length x, since the sagitta intersects the midpoint of the chord, we know that it is a part of a diameter of the circle. Since the diameter is twice the radius, the \"missing\" part of the diameter is (2r − x) in length. Using the fact that one part of one chord times the other part is equal to the same product taken along a chord intersecting the first chord, we find that (2r − x)x = (y / 2). Solving for r, we find the required result.",
"title": "Properties"
},
{
"paragraph_id": 44,
"text": "There are many compass-and-straightedge constructions resulting in circles.",
"title": "Compass and straightedge constructions"
},
{
"paragraph_id": 45,
"text": "The simplest and most basic is the construction given the centre of the circle and a point on the circle. Place the fixed leg of the compass on the centre point, the movable leg on the point on the circle and rotate the compass.",
"title": "Compass and straightedge constructions"
},
{
"paragraph_id": 46,
"text": "Apollonius of Perga showed that a circle may also be defined as the set of points in a plane having a constant ratio (other than 1) of distances to two fixed foci, A and B. (The set of points where the distances are equal is the perpendicular bisector of segment AB, a line.) That circle is sometimes said to be drawn about two points.",
"title": "Circle of Apollonius"
},
{
"paragraph_id": 47,
"text": "The proof is in two parts. First, one must prove that, given two foci A and B and a ratio of distances, any point P satisfying the ratio of distances must fall on a particular circle. Let C be another point, also satisfying the ratio and lying on segment AB. By the angle bisector theorem the line segment PC will bisect the interior angle APB, since the segments are similar:",
"title": "Circle of Apollonius"
},
{
"paragraph_id": 48,
"text": "Analogously, a line segment PD through some point D on AB extended bisects the corresponding exterior angle BPQ where Q is on AP extended. Since the interior and exterior angles sum to 180 degrees, the angle CPD is exactly 90 degrees; that is, a right angle. The set of points P such that angle CPD is a right angle forms a circle, of which CD is a diameter.",
"title": "Circle of Apollonius"
},
{
"paragraph_id": 49,
"text": "Second, see for a proof that every point on the indicated circle satisfies the given ratio.",
"title": "Circle of Apollonius"
},
{
"paragraph_id": 50,
"text": "A closely related property of circles involves the geometry of the cross-ratio of points in the complex plane. If A, B, and C are as above, then the circle of Apollonius for these three points is the collection of points P for which the absolute value of the cross-ratio is equal to one:",
"title": "Circle of Apollonius"
},
{
"paragraph_id": 51,
"text": "Stated another way, P is a point on the circle of Apollonius if and only if the cross-ratio [A, B; C, P] is on the unit circle in the complex plane.",
"title": "Circle of Apollonius"
},
{
"paragraph_id": 52,
"text": "If C is the midpoint of the segment AB, then the collection of points P satisfying the Apollonius condition",
"title": "Circle of Apollonius"
},
{
"paragraph_id": 53,
"text": "is not a circle, but rather a line.",
"title": "Circle of Apollonius"
},
{
"paragraph_id": 54,
"text": "Thus, if A, B, and C are given distinct points in the plane, then the locus of points P satisfying the above equation is called a \"generalised circle.\" It may either be a true circle or a line. In this sense a line is a generalised circle of infinite radius.",
"title": "Circle of Apollonius"
},
{
"paragraph_id": 55,
"text": "In every triangle a unique circle, called the incircle, can be inscribed such that it is tangent to each of the three sides of the triangle.",
"title": "Inscription in or circumscription about other figures"
},
{
"paragraph_id": 56,
"text": "About every triangle a unique circle, called the circumcircle, can be circumscribed such that it goes through each of the triangle's three vertices.",
"title": "Inscription in or circumscription about other figures"
},
{
"paragraph_id": 57,
"text": "A tangential polygon, such as a tangential quadrilateral, is any convex polygon within which a circle can be inscribed that is tangent to each side of the polygon. Every regular polygon and every triangle is a tangential polygon.",
"title": "Inscription in or circumscription about other figures"
},
{
"paragraph_id": 58,
"text": "A cyclic polygon is any convex polygon about which a circle can be circumscribed, passing through each vertex. A well-studied example is the cyclic quadrilateral. Every regular polygon and every triangle is a cyclic polygon. A polygon that is both cyclic and tangential is called a bicentric polygon.",
"title": "Inscription in or circumscription about other figures"
},
{
"paragraph_id": 59,
"text": "A hypocycloid is a curve that is inscribed in a given circle by tracing a fixed point on a smaller circle that rolls within and tangent to the given circle.",
"title": "Inscription in or circumscription about other figures"
},
{
"paragraph_id": 60,
"text": "The circle can be viewed as a limiting case of various other figures:",
"title": "Limiting case of other figures"
},
{
"paragraph_id": 61,
"text": "Consider a finite set of n {\\displaystyle n} points in the plane. The locus of points such that the sum of the squares of the distances to the given points is constant is a circle, whose centre is at the centroid of the given points. A generalization for higher powers of distances is obtained if under n {\\displaystyle n} points the vertices of the regular polygon P n {\\displaystyle P_{n}} are taken. The locus of points such that the sum of the 2 m {\\displaystyle 2m} -th power of distances d i {\\displaystyle d_{i}} to the vertices of a given regular polygon with circumradius R {\\displaystyle R} is constant is a circle, if",
"title": "Locus of constant sum"
},
{
"paragraph_id": 62,
"text": "whose centre is the centroid of the P n {\\displaystyle P_{n}} .",
"title": "Locus of constant sum"
},
{
"paragraph_id": 63,
"text": "In the case of the equilateral triangle, the loci of the constant sums of the second and fourth powers are circles, whereas for the square, the loci are circles for the constant sums of the second, fourth, and sixth powers. For the regular pentagon the constant sum of the eighth powers of the distances will be added and so forth.",
"title": "Locus of constant sum"
},
{
"paragraph_id": 64,
"text": "Squaring the circle is the problem, proposed by ancient geometers, of constructing a square with the same area as a given circle by using only a finite number of steps with compass and straightedge.",
"title": "Squaring the circle"
},
{
"paragraph_id": 65,
"text": "In 1882, the task was proven to be impossible, as a consequence of the Lindemann–Weierstrass theorem, which proves that pi (π) is a transcendental number, rather than an algebraic irrational number; that is, it is not the root of any polynomial with rational coefficients. Despite the impossibility, this topic continues to be of interest for pseudomath enthusiasts.",
"title": "Squaring the circle"
},
{
"paragraph_id": 66,
"text": "Defining a circle as the set of points with a fixed distance from a point, different shapes can be considered circles under different definitions of distance. In p-norm, distance is determined by",
"title": "Generalizations"
},
{
"paragraph_id": 67,
"text": "In Euclidean geometry, p = 2, giving the familiar",
"title": "Generalizations"
},
{
"paragraph_id": 68,
"text": "In taxicab geometry, p = 1. Taxicab circles are squares with sides oriented at a 45° angle to the coordinate axes. While each side would have length 2 r {\\displaystyle {\\sqrt {2}}r} using a Euclidean metric, where r is the circle's radius, its length in taxicab geometry is 2r. Thus, a circle's circumference is 8r. Thus, the value of a geometric analog to π {\\displaystyle \\pi } is 4 in this geometry. The formula for the unit circle in taxicab geometry is | x | + | y | = 1 {\\displaystyle |x|+|y|=1} in Cartesian coordinates and",
"title": "Generalizations"
},
{
"paragraph_id": 69,
"text": "in polar coordinates.",
"title": "Generalizations"
},
{
"paragraph_id": 70,
"text": "A circle of radius 1 (using this distance) is the von Neumann neighborhood of its centre.",
"title": "Generalizations"
},
{
"paragraph_id": 71,
"text": "A circle of radius r for the Chebyshev distance (L∞ metric) on a plane is also a square with side length 2r parallel to the coordinate axes, so planar Chebyshev distance can be viewed as equivalent by rotation and scaling to planar taxicab distance. However, this equivalence between L1 and L∞ metrics does not generalize to higher dimensions.",
"title": "Generalizations"
},
{
"paragraph_id": 72,
"text": "The circle is the one-dimensional hypersphere (the 1-sphere).",
"title": "Generalizations"
},
{
"paragraph_id": 73,
"text": "In topology, a circle is not limited to the geometric concept, but to all of its homeomorphisms. Two topological circles are equivalent if one can be transformed into the other via a deformation of R upon itself (known as an ambient isotopy).",
"title": "Generalizations"
}
] | A circle is a shape consisting of all points in a plane that are at a given distance from a given point, the centre. The distance between any point of the circle and the centre is called the radius. The circle has been known since before the beginning of recorded history. Natural circles are common, such as the full moon or a slice of round fruit. The circle is the basis for the wheel, which, with related inventions such as gears, makes much of modern machinery possible. In mathematics, the study of the circle has helped inspire the development of geometry, astronomy and calculus. | 2001-08-28T05:15:23Z | 2023-12-28T01:20:12Z | [
"Template:Sfrac",
"Template:Vague",
"Template:Pi",
"Template:Nobr",
"Template:Col-end",
"Template:Citation",
"Template:EB1911 poster",
"Template:PlanetMath",
"Template:Cite journal",
"Template:Commons and category",
"Template:Reflist",
"Template:Infobox polygon",
"Template:TOC limit",
"Template:Quotation",
"Template:Main article",
"Template:Nowrap",
"Template:Math",
"Template:Col-begin",
"Template:Authority control",
"Template:Short description",
"Template:Use dmy dates",
"Template:Main",
"Template:Rp",
"Template:Wikiquote",
"Template:Springer",
"Template:Cite web",
"Template:Anchor",
"Template:Webarchive",
"Template:Pp-semi-indef",
"Template:Clear",
"Template:Citation needed",
"Template:Col-break",
"Template:Cite book",
"Template:About",
"Template:Redirect2",
"Template:Use British English",
"Template:General geometry",
"Template:See also",
"Template:Cite encyclopedia",
"Template:MathWorld"
] | https://en.wikipedia.org/wiki/Circle |
6,221 | Cardinal (Catholic Church) | A cardinal (Latin: Sanctae Romanae Ecclesiae cardinalis, lit. 'cardinal of the Holy Roman Church') is a senior member of the clergy of the Catholic Church. Cardinals are created by the pope and typically hold the title for life. Collectively, they constitute the College of Cardinals.
The most solemn responsibility of the cardinals is to elect a new pope in a conclave, almost always from among themselves (with a few historical exceptions), when the Holy See is vacant. During the period between a pope's death or resignation and the election of his successor, the day-to-day governance of the Holy See is in the hands of the College of Cardinals. The right to participate in a conclave is limited to cardinals who have not reached the age of 80 years by the day the vacancy occurs. In addition, cardinals collectively participate in papal consistories (which generally take place annually), in which matters of importance to the Church are considered and new cardinals may be created. Cardinals of working age are also appointed to roles overseeing dicasteries of the Roman Curia, the central administration of the Catholic Church.
Cardinals are drawn from a variety of backgrounds, being appointed as cardinals in addition to their existing roles within the Church. Most cardinals are bishops and archbishops leading dioceses and archdioceses around the world – often the most prominent diocese or archdiocese in their country. Others are titular bishops who are current or former officials within the Roman Curia (generally the heads of dicasteries and other bodies linked to the Curia). A very small number are priests recognised by the pope for their service to the Church; as canon law requires them to be generally consecrated as bishops before they are made cardinals, but some are granted a papal dispensation. There are no strict criteria for elevation to the College of Cardinals. Since 1917, a potential cardinal must already be at least a priest, but laymen have been cardinals in the past. The selection is entirely up to the pope and tradition is his only guide.
As of 5 December 2023, there are 241 serving cardinals, of whom 134 are eligible to vote in a conclave to elect a new pope.
There is general disagreement about the origin of the term, but a chief consensus that "cardinalis" is etymologically from the Latin word cardo (meaning "pivot" or "hinge") was first used in late antiquity to designate a bishop or priest who was incorporated into a church for which he had not originally been ordained. In Rome the first persons to be called cardinals were the deacons of the seven regions of the city at the beginning of the 6th century, when the word began to mean "principal", "eminent", or "superior". The name was also given to the senior priest in each of the "title" churches (the parish churches) of Rome and to the bishops of the seven sees surrounding the city. By the 8th century the Roman cardinals constituted a privileged class among the Roman clergy. They took part in the administration of the church of Rome and in the papal liturgy. By decree of a synod of 769, only a cardinal was eligible to become Bishop of Rome. Cardinals were granted the privilege of wearing the red hat by Pope Innocent IV in 1244.
In cities other than Rome, the name cardinal began to be applied to certain church men as a mark of honour. The earliest example of this occurs in a letter sent by Pope Zacharias in 747 to Pippin III (the Short), ruler of the Franks, in which Zacharias applied the title to the priests of Paris to distinguish them from country clergy. This meaning of the word spread rapidly, and from the 9th century various episcopal cities had a special class among the clergy known as cardinals. The use of the title was reserved for the cardinals of Rome in 1567 by Pius V.
In 1059 (five years after the East-West Schism), the right of electing the pope was reserved to the principal clergy of Rome and the bishops of the seven suburbicarian sees. In the 12th century the practice of appointing ecclesiastics from outside Rome as cardinals began, with each of them assigned a church in Rome as his titular church or linked with one of the suburbicarian dioceses, while still being incardinated in a diocese other than that of Rome.
The term cardinal at one time applied to any priest permanently assigned or incardinated to a church, or specifically to the senior priest of an important church, based on the Latin cardo (hinge), meaning "pivotal" as in "principal" or "chief". The term was applied in this sense as early as the 9th century to the priests of the tituli (parishes) of the diocese of Rome.
In the year 1563, the Ecumenical Council of Trent, headed by Pope Pius IV, wrote about the importance of selecting good cardinals: "nothing is more necessary to the Church of God than that the holy Roman pontiff apply that solicitude which by the duty of his office he owes the universal Church in a very special way by associating with himself as cardinals the most select persons only, and appoint to each church most eminently upright and competent shepherds; and this the more so, because our Lord Jesus Christ will require at his hands the blood of the sheep of Christ that perish through the evil government of shepherds who are negligent and forgetful of their office."
The earlier influence of temporal rulers, notably the kings of France, reasserted itself through the influence of cardinals of certain nationalities or politically significant movements. Traditions even developed entitling certain monarchs, including those of Austria, Spain, and France, to nominate one of their trusted clerical subjects to be created cardinal, a so-called "crown-cardinal".
In early modern times, cardinals often had important roles in secular affairs. In some cases, they took on powerful positions in government. In Henry VIII's England, his chief minister was for some time Cardinal Wolsey. Cardinal Richelieu's power was so great that he was for many years effectively the ruler of France. Richelieu's successor was also a cardinal, Jules Mazarin. Guillaume Dubois and André-Hercule de Fleury complete the list of the four great cardinals to have ruled France. In Portugal, due to a succession crisis, one cardinal, Henry of Portugal, was crowned king, the only example of a cardinal-king.
While the incumbents of some sees are regularly made cardinals, and some countries are entitled to at least one cardinal by concordat (usually earning either its primate or the metropolitan of the capital city the cardinal's hat), almost no see carries an actual right to the cardinalate, not even if its bishop is a patriarch: the notable exception is the Patriarch of Lisbon who, by Pope Clement XII's 1737 bull Inter praecipuas apostolici ministerii, is accorded the right to be elevated to the rank of cardinal in the consistory following his appointment.
In 1059, Pope Nicholas II gave cardinals the right to elect the Bishop of Rome in the papal bull In nomine Domini. For a time this power was assigned exclusively to the cardinal bishops, but in 1179 the Third Lateran Council restored the right to the whole body of cardinals.
In 1586, Pope Sixtus V limited the number of cardinals to 70: six cardinal bishops, 50 cardinal priests, and 14 cardinal deacons. Pope John XXIII exceeded that limit citing the need to staff Church offices. In November 1970 in Ingravescentem aetatem, Pope Paul VI established that electors would be under the age of eighty years. When it took effect on 1 January 1971, it deprived 25 cardinals of the right to participate in a conclave. In October 1975 in Romano Pontifici eligendo, he set the maximum number of electors at 120, while establishing no limit on the overall size of the college.
Popes can set aside church laws and they have regularly brought the number of cardinals under the age of 80 to more than 120, twice reaching as high as 135 with Pope John Paul II's consistories of February 2001 and October 2003. No more than 120 electors have ever participated in a conclave, but most canon lawyers believe that if their number exceeded 120 they would all participate.
Pope Paul VI also increased the number of cardinal bishops by assigning that rank, in 1965, to patriarchs of the Eastern Catholic Churches when named cardinals. In 2018, Pope Francis expanded the cardinal bishops of Roman title, because this had not been done despite recent decades' expansion in the two lower orders of cardinals, besides having all six such cardinals being over the age limit for a conclave.
Each cardinal is assigned a titular church upon his creation, which is always a church in the city of Rome. Through the process of opting (optazione), a cardinal can raise through the ranks from cardinal deacon to priest, and from cardinal priest to that of cardinal bishop - in which case he obtains one of the suburbicarian sees located around the city of Rome. The only exception is for patriarchs of the Eastern Catholic Churches. Nevertheless, cardinals possess no power of governance nor are they to intervene in any way in matters which pertain to the administration of goods, discipline, or the service of their titular churches. They are allowed to celebrate Mass and hear confessions and lead visits and pilgrimages to their titular churches, in coordination with the staff of the church. They often support their churches monetarily, and many cardinals do keep in contact with the pastoral staffs of their titular churches. The term cardinal is from the Latin word "cardo" meaning a hinge. Here it means a "door", an example of synecdoche, a figure of speech whereby the part refers to the whole. The "door" is the address of the titular church from which the cardinal derives his membership of the Roman clergy, who elect the pope.
The Dean of the College of Cardinals in addition to such a titular church also receives the titular bishopric of Ostia, the primary suburbicarian see. Cardinals governing a particular church retain that church.
In 1630, Pope Urban VIII decreed their title to be Eminence (previously, it had been "illustrissimo" and "reverendissimo") and decreed that their secular rank would equate to Prince, making them second only to the pope and crowned monarchs.
In accordance with tradition, they sign by placing the title "Cardinal" (abbreviated Card.) after their personal name and before their surname as, for instance, "John Card(inal) Doe" or, in Latin, "Ioannes Card(inalis) Doe". Some writers, such as James-Charles Noonan, hold that, in the case of cardinals, the form used for signatures should be used also when referring to them in English. However, official sources, such as the Catholic News Service, say that the correct form for referring to a cardinal in English is normally as "Cardinal [First name] [Surname]". This is the rule given also in stylebooks not associated with the church. This style is also generally followed on the websites of the Holy See and episcopal conferences. Oriental patriarchs who are created cardinals customarily use "Sanctae Ecclesiae Cardinalis" as their full title, probably because they do not belong to the Roman clergy.
The [First name] Cardinal [Surname] order is used in the Latin proclamation of the election of a new pope by the cardinal protodeacon, if the new pope is a cardinal, as has been the case since 1378.
The term Prince of the Church has historically been applied to cardinals of the Catholic church, and sometimes more broadly to senior members of the church hierarchy. It has been rejected by Pope Francis, who stated to a group of newly created cardinals "He (Jesus) does not call you to become 'princes' of the Church, to 'sit on his right or on his left.' He calls you to serve like Him and with Him." The term is still applied, both seriously and as a criticism of the perceived attitudes of some cardinals.
Cardinal bishops (cardinals of the episcopal order; Latin: cardinales episcopi) are the senior order of cardinals. Though in modern times the vast majority of cardinals are also bishops or archbishops, few are "cardinal bishops". For most of the second millennium there were six cardinal bishops, each presiding over one of the seven suburbicarian sees around Rome: Ostia, Albano, Porto and Santa Rufina, Palestrina, Sabina and Mentana, Frascati, and Velletri. Velletri was united with Ostia from 1150 until 1914, when Pope Pius X separated them again, but decreed that whichever cardinal bishop became Dean of the College of Cardinals would keep the suburbicarian see he already held, adding to it that of Ostia, with the result that there continued to be only six cardinal bishops. Since 1962, the cardinal bishops have only a titular relationship with the suburbicarian sees, each of which is governed by a separate ordinary.
Until 1961, membership in the order of cardinal bishops was achieved through precedence in the College of Cardinals. When a suburbicarian see fell vacant, the most senior cardinal by precedence could exercise his option to claim the see and be promoted to the order of cardinal bishops. Pope John XXIII abolished that privilege on 10 March 1961 and made the right to promote someone to the order of cardinal bishops the sole prerogative of the pope.
In 1965, Pope Paul VI decreed in his motu proprio Ad purpuratorum Patrum Collegium that patriarchs of the Eastern Catholic Churches who were named cardinals (i.e. "cardinal patriarchs") would also be cardinal bishops, ranking after the six Roman rite cardinal bishops of the suburbicarian sees. (Latin Church patriarchs who become cardinals are cardinal priests, not cardinal bishops: for example Angelo Scola was made Patriarch of Venice in 2002 and cardinal priest of Santi XII Apostoli in 2003.) Those of cardinal patriarch rank continue to hold their patriarchal see and are not assigned any Roman title (suburbicarian see or title or deaconry).
At the June 2018 consistory, Pope Francis increased the number of Latin Church cardinal bishops to match the expansion in cardinal priests and cardinal deacons in recent decades. He elevated four cardinals to this rank granting their titular churches and deaconries suburbicarian rank pro hac vice (temporarily) and making them equivalent to suburbicarian see titles. At the time of the announcement, all six cardinal bishops of suburbicarian see titles, as well as two of the three cardinal patriarchs, were non-electors as they had reached the age of 80. Pope Francis created another cardinal bishop in the same way on 1 May 2020, bringing the number of Latin Church cardinal bishops to eleven.
The Dean of the College of Cardinals, the highest ranking cardinal, was formerly the longest serving cardinal bishop, but since 1965 is elected by the Latin Church cardinal bishops from among their number, subject to papal approval. Likewise the Vice-Dean, formerly the second longest serving, is also elected. Seniority of the remaining Latin Church cardinal bishops is still by date of appointment to the rank.
Cardinal priests (Latin: cardinales presbyteri) are the most numerous of the three orders of cardinals in the Catholic Church, ranking above the cardinal deacons and below the cardinal bishops. Those who are named cardinal priests today are generally also bishops of important dioceses throughout the world, though some hold Curial positions.
In modern times, the term "cardinal priest" is interpreted as meaning a cardinal who is of the order of priests. Originally, however, this referred to certain key priests of important churches of the Diocese of Rome, who were recognized as the cardinal priests, the important priests chosen by the pope to advise him in his duties as Bishop of Rome (the Latin cardo means "hinge"). Certain clerics in many dioceses at the time, not just that of Rome, were said to be the key personnel—the term gradually became exclusive to Rome to indicate those entrusted with electing the Bishop of Rome, the pope.
While the cardinalate has long been expanded beyond the Roman pastoral clergy and Roman Curia, every cardinal priest has a titular church in Rome, though they may be bishops or archbishops elsewhere, just as cardinal bishops were given one of the suburbicarian dioceses around Rome. Pope Paul VI abolished all administrative rights cardinals had with regard to their titular churches, though the cardinal's name and coat of arms are still posted in the church, and they are expected to celebrate Mass and preach there if convenient when they are in Rome.
While the number of cardinals was small from the times of the Roman Empire to the Renaissance, and frequently smaller than the number of recognized churches entitled to a cardinal priest, in the 16th century the college expanded markedly. In 1587, Pope Sixtus V sought to arrest this growth by fixing the maximum size of the college at 70, including 50 cardinal priests, about twice the historical number. This limit was respected until 1958, and the list of titular churches modified only on rare occasions, generally when a building fell into disrepair. When Pope John XXIII abolished the limit, he began to add new churches to the list, which Popes Paul VI and John Paul II continued to do. Today there are close to 150 titular churches, out of over 300 churches in Rome.
The cardinal who is the longest-serving member of the order of cardinal priests is titled cardinal protopriest. He had certain ceremonial duties in the conclave that have effectively ceased because he would generally have already reached age 80, at which cardinals are barred from the conclave. The current cardinal protopriest is Michael Michai Kitbunchu of Thailand.
The cardinal deacons (Latin: cardinales diaconi) are the lowest-ranking cardinals. Cardinals elevated to the diaconal order are either officials of the Roman Curia or priests elevated after their 80th birthday. Bishops with diocesan responsibilities, however, are created cardinal priests.
Cardinal deacons derive originally from the seven deacons in the Papal Household who supervised the Church's works in the seven districts of Rome during the early Middle Ages, when church administration was effectively the government of Rome and provided all social services. They came to be called "cardinal deacons" by the late eighth century, and they were granted active rights in papal elections and made eligible for the election as pope by the decree of 769.
Cardinals elevated to the diaconal order are mainly officials of the Roman Curia holding various posts in the church administration. Their number and influence has varied through the years. While historically predominantly Italian the group has become much more internationally diverse in later years. While in 1939 about half were Italian, by 1994 the number was reduced to one third. Their influence in the election of the pope has been considered important. They are better informed and connected than the dislocated cardinals but their level of unity has been varied. Under the 1587 decree of Pope Sixtus V, which fixed the maximum size of the College of Cardinals, there were 14 cardinal deacons. Later the number increased. As late as 1939 almost half of the cardinals were members of the Curia. Pius XII reduced this percentage to 24 percent. John XXIII brought it back up to 37 percent but Paul VI brought it down to 27 percent where John Paul II maintained this ratio.
As of 2005, there were over 50 churches recognized as cardinalatial deaconries, though there were only 30 cardinals of the order of deacons. Cardinal deacons have long enjoyed the right to "opt for the order of cardinal priests" (optazione) after they have been cardinal deacons for 10 years. They may on such elevation take a vacant "title" (a church allotted to a cardinal priest as the church in Rome with which he is associated) or their diaconal church may be temporarily elevated to a cardinal priest's "title" for that occasion. When elevated to cardinal priests, they take their precedence according to the day they were first made cardinal deacons (thus ranking above cardinal priests who were elevated to the college after them, regardless of order).
When not celebrating Mass but still serving a liturgical function, such as the semiannual Urbi et Orbi papal blessing, some Papal Masses and some events at Ecumenical Councils, cardinal deacons can be recognized by the dalmatics they would don with the simple white mitre (so called mitra simplex).
The cardinal protodeacon is the senior cardinal deacon in order of appointment to the College of Cardinals. If he is a cardinal elector and participates in a conclave, he announces a new pope's election and name from the central balcony of St. Peter's Basilica in Vatican City. The protodeacon also bestows the pallium on the new pope and crowns him with the papal tiara, although the crowning has not been celebrated since Pope John Paul I opted for a simpler papal inauguration ceremony in 1978. The current cardinal protodeacon is Renato Raffaele Martino.
* Ceased to be protodeacon upon being raised to the order of cardinal-priest† Was protodeacon at time of death
The Cardinal Camerlengo of the Holy Roman Church, assisted by the Vice-Camerlengo and the other prelates of the office known as the Apostolic Camera, has functions that in essence are limited to a period of sede vacante of the papacy. He is to collate information about the financial situation of all administrations dependent on the Holy See and present the results to the College of Cardinals, as they gather for the papal conclave.
Until 1918, any cleric, even one only in minor orders, could be created a cardinal (see "lay cardinals", below), but enrolled only in the order of cardinal deacons. For example, in the 16th century, Reginald Pole was a cardinal for 18 years before he was ordained a priest. The 1917 Code of Canon Law mandated that all cardinals, even cardinal deacons, had to be priests, and, in 1962, Pope John XXIII set the norm that all cardinals be consecrated as bishops, even if they are only priests at the time of appointment. As a consequence of these two changes, canon 351 of the 1983 Code of Canon Law requires that a cardinal be at least in the order of priesthood at his appointment, and that those who are not already bishops must receive episcopal consecration. Several cardinals near to or over the age of 80 when appointed have obtained dispensation from the rule of having to be a bishop. These were all appointed cardinal-deacons, but Roberto Tucci and Albert Vanhoye lived long enough to exercise the right of option and be promoted to the rank of cardinal-priest. No cardinal who was not a bishop has participated in a papal conclave since the 1962 rule change. However, as of 21 December 2023 Ángel Fernández Artime, Rector Major of the Salesians, who was created a cardinal by Pope Francis on 30 September 2023, has not been consecrated a bishop and is aged 63, is a cardinal elector.
A cardinal who is not a bishop is entitled to wear and use the episcopal vestments and other pontificalia (episcopal regalia: mitre, crozier, zucchetto, pectoral cross, and ring). He has both actual and honorary precedence over archbishops, and bishops who are not cardinals. However, he cannot perform the sacrament of ordination or other rites reserved solely to bishops.
At various times, there have been cardinals who had only received first tonsure and minor orders but not yet been ordained as deacons or priests. Though clerics, they were inaccurately called "lay cardinals". Teodolfo Mertel was among the last of the lay cardinals. When he died in 1899 he was the last surviving cardinal who was not at least ordained a priest. With the revision of the Code of Canon Law promulgated in 1917 by Pope Benedict XV, only those who are already priests or bishops may be appointed cardinals. Since the time of Pope John XXIII a priest who is appointed a cardinal must be consecrated a bishop, unless he obtains a dispensation.
In addition to the named cardinals, the pope may name secret cardinals or cardinals in pectore (Latin for in the breast). During the Western Schism, many cardinals were created by the contending popes. Beginning with the reign of Pope Martin V, cardinals were created without publishing their names until later, a practice termed creati et reservati in pectore. A cardinal named in pectore is known only to the pope. In the modern era, popes have named cardinals in pectore to protect them or their congregations from political reprisals. If conditions change, the pope makes the appointment public. The cardinal in question then ranks in precedence with those made cardinals at the time of his in pectore appointment. If a pope dies before revealing the identity of an in pectore cardinal, the person's status as cardinal expires. The last pope known to have named a cardinal in pectore is Pope John Paul II, who named four, including one whose identity was never revealed.
When in choir dress, a Latin Church cardinal wears scarlet garments—the blood-like red symbolizes a cardinal's willingness to die for his faith. Excluding the rochet — which is always white—the scarlet garments include the cassock, mozzetta, and biretta (over the usual scarlet zucchetto). The biretta of a cardinal is distinctive not merely for its scarlet color, but also for the fact that it does not have a pompon or tassel on the top as do the birettas of other prelates. Until the 1460s, it was customary for cardinals to wear a violet or blue cape unless granted the privilege of wearing red when acting on papal business. His normal-wear cassock is black but has scarlet piping and a scarlet fascia (sash). Occasionally, a cardinal wears a scarlet ferraiolo which is a cape worn over the shoulders, tied at the neck in a bow by narrow strips of cloth in the front, without any 'trim' or piping on it. It is because of the scarlet color of cardinals' vesture that the bird of the same name has become known as such.
Eastern Catholic cardinals continue to wear the normal dress appropriate to their liturgical tradition, though some may line their cassocks with scarlet and wear scarlet fascias, or in some cases, wear Eastern-style cassocks entirely of scarlet.
In previous times, at the consistory at which the pope named a new cardinal, he would bestow upon him a distinctive wide-brimmed hat called a galero. This custom was discontinued in 1969 and the investiture now takes place with the scarlet biretta. In ecclesiastical heraldry, however, the scarlet galero is still displayed on the cardinal's coat of arms. Cardinals had the right to display the galero in their cathedral, and when a cardinal died, it would be suspended from the ceiling above his tomb. Some cardinals will still have a galero made, even though it is not officially part of their apparel.
To symbolize their bond with the papacy, the pope gives each newly appointed cardinal a gold ring, which is traditionally kissed by Catholics when greeting a cardinal (as with a bishop's episcopal ring). Before the new uniformity imposed by John Paul II, each cardinal was given a ring, the central piece of which was a gem, usually a sapphire, with the pope's stemma engraved on the inside. There is now no gemstone, and the pope chooses the image on the outside: under Pope Benedict XVI it was a modern depiction of the crucifixion of Jesus, with Mary and John to each side. The ring includes the pope's coat of arms on the inside.
Cardinals have in canon law a "privilege of forum" (i.e., exemption from being judged by ecclesiastical tribunals of ordinary rank): only the pope is competent to judge them in matters subject to ecclesiastical jurisdiction (cases that refer to matters that are spiritual or linked with the spiritual, or with regard to infringement of ecclesiastical laws and whatever contains an element of sin, where culpability must be determined and the appropriate ecclesiastical penalty imposed). The pope either decides the case himself or delegates the decision to a tribunal, usually one of the tribunals or congregations of the Roman Curia. Without such delegation, no ecclesiastical court, even the Roman Rota, is competent to judge a canon law case against a cardinal.
Additionally, canon law gives cardinals the faculty of hearing confessions validly and licitly everywhere, whereas other priests and bishops must be granted this faculty and might be restricted in its use by the local bishop. | [
{
"paragraph_id": 0,
"text": "A cardinal (Latin: Sanctae Romanae Ecclesiae cardinalis, lit. 'cardinal of the Holy Roman Church') is a senior member of the clergy of the Catholic Church. Cardinals are created by the pope and typically hold the title for life. Collectively, they constitute the College of Cardinals.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The most solemn responsibility of the cardinals is to elect a new pope in a conclave, almost always from among themselves (with a few historical exceptions), when the Holy See is vacant. During the period between a pope's death or resignation and the election of his successor, the day-to-day governance of the Holy See is in the hands of the College of Cardinals. The right to participate in a conclave is limited to cardinals who have not reached the age of 80 years by the day the vacancy occurs. In addition, cardinals collectively participate in papal consistories (which generally take place annually), in which matters of importance to the Church are considered and new cardinals may be created. Cardinals of working age are also appointed to roles overseeing dicasteries of the Roman Curia, the central administration of the Catholic Church.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Cardinals are drawn from a variety of backgrounds, being appointed as cardinals in addition to their existing roles within the Church. Most cardinals are bishops and archbishops leading dioceses and archdioceses around the world – often the most prominent diocese or archdiocese in their country. Others are titular bishops who are current or former officials within the Roman Curia (generally the heads of dicasteries and other bodies linked to the Curia). A very small number are priests recognised by the pope for their service to the Church; as canon law requires them to be generally consecrated as bishops before they are made cardinals, but some are granted a papal dispensation. There are no strict criteria for elevation to the College of Cardinals. Since 1917, a potential cardinal must already be at least a priest, but laymen have been cardinals in the past. The selection is entirely up to the pope and tradition is his only guide.",
"title": ""
},
{
"paragraph_id": 3,
"text": "As of 5 December 2023, there are 241 serving cardinals, of whom 134 are eligible to vote in a conclave to elect a new pope.",
"title": ""
},
{
"paragraph_id": 4,
"text": "There is general disagreement about the origin of the term, but a chief consensus that \"cardinalis\" is etymologically from the Latin word cardo (meaning \"pivot\" or \"hinge\") was first used in late antiquity to designate a bishop or priest who was incorporated into a church for which he had not originally been ordained. In Rome the first persons to be called cardinals were the deacons of the seven regions of the city at the beginning of the 6th century, when the word began to mean \"principal\", \"eminent\", or \"superior\". The name was also given to the senior priest in each of the \"title\" churches (the parish churches) of Rome and to the bishops of the seven sees surrounding the city. By the 8th century the Roman cardinals constituted a privileged class among the Roman clergy. They took part in the administration of the church of Rome and in the papal liturgy. By decree of a synod of 769, only a cardinal was eligible to become Bishop of Rome. Cardinals were granted the privilege of wearing the red hat by Pope Innocent IV in 1244.",
"title": "History"
},
{
"paragraph_id": 5,
"text": "In cities other than Rome, the name cardinal began to be applied to certain church men as a mark of honour. The earliest example of this occurs in a letter sent by Pope Zacharias in 747 to Pippin III (the Short), ruler of the Franks, in which Zacharias applied the title to the priests of Paris to distinguish them from country clergy. This meaning of the word spread rapidly, and from the 9th century various episcopal cities had a special class among the clergy known as cardinals. The use of the title was reserved for the cardinals of Rome in 1567 by Pius V.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "In 1059 (five years after the East-West Schism), the right of electing the pope was reserved to the principal clergy of Rome and the bishops of the seven suburbicarian sees. In the 12th century the practice of appointing ecclesiastics from outside Rome as cardinals began, with each of them assigned a church in Rome as his titular church or linked with one of the suburbicarian dioceses, while still being incardinated in a diocese other than that of Rome.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "The term cardinal at one time applied to any priest permanently assigned or incardinated to a church, or specifically to the senior priest of an important church, based on the Latin cardo (hinge), meaning \"pivotal\" as in \"principal\" or \"chief\". The term was applied in this sense as early as the 9th century to the priests of the tituli (parishes) of the diocese of Rome.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "In the year 1563, the Ecumenical Council of Trent, headed by Pope Pius IV, wrote about the importance of selecting good cardinals: \"nothing is more necessary to the Church of God than that the holy Roman pontiff apply that solicitude which by the duty of his office he owes the universal Church in a very special way by associating with himself as cardinals the most select persons only, and appoint to each church most eminently upright and competent shepherds; and this the more so, because our Lord Jesus Christ will require at his hands the blood of the sheep of Christ that perish through the evil government of shepherds who are negligent and forgetful of their office.\"",
"title": "History"
},
{
"paragraph_id": 9,
"text": "The earlier influence of temporal rulers, notably the kings of France, reasserted itself through the influence of cardinals of certain nationalities or politically significant movements. Traditions even developed entitling certain monarchs, including those of Austria, Spain, and France, to nominate one of their trusted clerical subjects to be created cardinal, a so-called \"crown-cardinal\".",
"title": "History"
},
{
"paragraph_id": 10,
"text": "In early modern times, cardinals often had important roles in secular affairs. In some cases, they took on powerful positions in government. In Henry VIII's England, his chief minister was for some time Cardinal Wolsey. Cardinal Richelieu's power was so great that he was for many years effectively the ruler of France. Richelieu's successor was also a cardinal, Jules Mazarin. Guillaume Dubois and André-Hercule de Fleury complete the list of the four great cardinals to have ruled France. In Portugal, due to a succession crisis, one cardinal, Henry of Portugal, was crowned king, the only example of a cardinal-king.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "While the incumbents of some sees are regularly made cardinals, and some countries are entitled to at least one cardinal by concordat (usually earning either its primate or the metropolitan of the capital city the cardinal's hat), almost no see carries an actual right to the cardinalate, not even if its bishop is a patriarch: the notable exception is the Patriarch of Lisbon who, by Pope Clement XII's 1737 bull Inter praecipuas apostolici ministerii, is accorded the right to be elevated to the rank of cardinal in the consistory following his appointment.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "In 1059, Pope Nicholas II gave cardinals the right to elect the Bishop of Rome in the papal bull In nomine Domini. For a time this power was assigned exclusively to the cardinal bishops, but in 1179 the Third Lateran Council restored the right to the whole body of cardinals.",
"title": "Papal elections"
},
{
"paragraph_id": 13,
"text": "In 1586, Pope Sixtus V limited the number of cardinals to 70: six cardinal bishops, 50 cardinal priests, and 14 cardinal deacons. Pope John XXIII exceeded that limit citing the need to staff Church offices. In November 1970 in Ingravescentem aetatem, Pope Paul VI established that electors would be under the age of eighty years. When it took effect on 1 January 1971, it deprived 25 cardinals of the right to participate in a conclave. In October 1975 in Romano Pontifici eligendo, he set the maximum number of electors at 120, while establishing no limit on the overall size of the college.",
"title": "Numbers"
},
{
"paragraph_id": 14,
"text": "Popes can set aside church laws and they have regularly brought the number of cardinals under the age of 80 to more than 120, twice reaching as high as 135 with Pope John Paul II's consistories of February 2001 and October 2003. No more than 120 electors have ever participated in a conclave, but most canon lawyers believe that if their number exceeded 120 they would all participate.",
"title": "Numbers"
},
{
"paragraph_id": 15,
"text": "Pope Paul VI also increased the number of cardinal bishops by assigning that rank, in 1965, to patriarchs of the Eastern Catholic Churches when named cardinals. In 2018, Pope Francis expanded the cardinal bishops of Roman title, because this had not been done despite recent decades' expansion in the two lower orders of cardinals, besides having all six such cardinals being over the age limit for a conclave.",
"title": "Numbers"
},
{
"paragraph_id": 16,
"text": "Each cardinal is assigned a titular church upon his creation, which is always a church in the city of Rome. Through the process of opting (optazione), a cardinal can raise through the ranks from cardinal deacon to priest, and from cardinal priest to that of cardinal bishop - in which case he obtains one of the suburbicarian sees located around the city of Rome. The only exception is for patriarchs of the Eastern Catholic Churches. Nevertheless, cardinals possess no power of governance nor are they to intervene in any way in matters which pertain to the administration of goods, discipline, or the service of their titular churches. They are allowed to celebrate Mass and hear confessions and lead visits and pilgrimages to their titular churches, in coordination with the staff of the church. They often support their churches monetarily, and many cardinals do keep in contact with the pastoral staffs of their titular churches. The term cardinal is from the Latin word \"cardo\" meaning a hinge. Here it means a \"door\", an example of synecdoche, a figure of speech whereby the part refers to the whole. The \"door\" is the address of the titular church from which the cardinal derives his membership of the Roman clergy, who elect the pope.",
"title": "Titular churches"
},
{
"paragraph_id": 17,
"text": "The Dean of the College of Cardinals in addition to such a titular church also receives the titular bishopric of Ostia, the primary suburbicarian see. Cardinals governing a particular church retain that church.",
"title": "Titular churches"
},
{
"paragraph_id": 18,
"text": "In 1630, Pope Urban VIII decreed their title to be Eminence (previously, it had been \"illustrissimo\" and \"reverendissimo\") and decreed that their secular rank would equate to Prince, making them second only to the pope and crowned monarchs.",
"title": "Title and reference style"
},
{
"paragraph_id": 19,
"text": "In accordance with tradition, they sign by placing the title \"Cardinal\" (abbreviated Card.) after their personal name and before their surname as, for instance, \"John Card(inal) Doe\" or, in Latin, \"Ioannes Card(inalis) Doe\". Some writers, such as James-Charles Noonan, hold that, in the case of cardinals, the form used for signatures should be used also when referring to them in English. However, official sources, such as the Catholic News Service, say that the correct form for referring to a cardinal in English is normally as \"Cardinal [First name] [Surname]\". This is the rule given also in stylebooks not associated with the church. This style is also generally followed on the websites of the Holy See and episcopal conferences. Oriental patriarchs who are created cardinals customarily use \"Sanctae Ecclesiae Cardinalis\" as their full title, probably because they do not belong to the Roman clergy.",
"title": "Title and reference style"
},
{
"paragraph_id": 20,
"text": "The [First name] Cardinal [Surname] order is used in the Latin proclamation of the election of a new pope by the cardinal protodeacon, if the new pope is a cardinal, as has been the case since 1378.",
"title": "Title and reference style"
},
{
"paragraph_id": 21,
"text": "The term Prince of the Church has historically been applied to cardinals of the Catholic church, and sometimes more broadly to senior members of the church hierarchy. It has been rejected by Pope Francis, who stated to a group of newly created cardinals \"He (Jesus) does not call you to become 'princes' of the Church, to 'sit on his right or on his left.' He calls you to serve like Him and with Him.\" The term is still applied, both seriously and as a criticism of the perceived attitudes of some cardinals.",
"title": "Title and reference style"
},
{
"paragraph_id": 22,
"text": "Cardinal bishops (cardinals of the episcopal order; Latin: cardinales episcopi) are the senior order of cardinals. Though in modern times the vast majority of cardinals are also bishops or archbishops, few are \"cardinal bishops\". For most of the second millennium there were six cardinal bishops, each presiding over one of the seven suburbicarian sees around Rome: Ostia, Albano, Porto and Santa Rufina, Palestrina, Sabina and Mentana, Frascati, and Velletri. Velletri was united with Ostia from 1150 until 1914, when Pope Pius X separated them again, but decreed that whichever cardinal bishop became Dean of the College of Cardinals would keep the suburbicarian see he already held, adding to it that of Ostia, with the result that there continued to be only six cardinal bishops. Since 1962, the cardinal bishops have only a titular relationship with the suburbicarian sees, each of which is governed by a separate ordinary.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 23,
"text": "Until 1961, membership in the order of cardinal bishops was achieved through precedence in the College of Cardinals. When a suburbicarian see fell vacant, the most senior cardinal by precedence could exercise his option to claim the see and be promoted to the order of cardinal bishops. Pope John XXIII abolished that privilege on 10 March 1961 and made the right to promote someone to the order of cardinal bishops the sole prerogative of the pope.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 24,
"text": "In 1965, Pope Paul VI decreed in his motu proprio Ad purpuratorum Patrum Collegium that patriarchs of the Eastern Catholic Churches who were named cardinals (i.e. \"cardinal patriarchs\") would also be cardinal bishops, ranking after the six Roman rite cardinal bishops of the suburbicarian sees. (Latin Church patriarchs who become cardinals are cardinal priests, not cardinal bishops: for example Angelo Scola was made Patriarch of Venice in 2002 and cardinal priest of Santi XII Apostoli in 2003.) Those of cardinal patriarch rank continue to hold their patriarchal see and are not assigned any Roman title (suburbicarian see or title or deaconry).",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 25,
"text": "At the June 2018 consistory, Pope Francis increased the number of Latin Church cardinal bishops to match the expansion in cardinal priests and cardinal deacons in recent decades. He elevated four cardinals to this rank granting their titular churches and deaconries suburbicarian rank pro hac vice (temporarily) and making them equivalent to suburbicarian see titles. At the time of the announcement, all six cardinal bishops of suburbicarian see titles, as well as two of the three cardinal patriarchs, were non-electors as they had reached the age of 80. Pope Francis created another cardinal bishop in the same way on 1 May 2020, bringing the number of Latin Church cardinal bishops to eleven.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 26,
"text": "The Dean of the College of Cardinals, the highest ranking cardinal, was formerly the longest serving cardinal bishop, but since 1965 is elected by the Latin Church cardinal bishops from among their number, subject to papal approval. Likewise the Vice-Dean, formerly the second longest serving, is also elected. Seniority of the remaining Latin Church cardinal bishops is still by date of appointment to the rank.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 27,
"text": "Cardinal priests (Latin: cardinales presbyteri) are the most numerous of the three orders of cardinals in the Catholic Church, ranking above the cardinal deacons and below the cardinal bishops. Those who are named cardinal priests today are generally also bishops of important dioceses throughout the world, though some hold Curial positions.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 28,
"text": "In modern times, the term \"cardinal priest\" is interpreted as meaning a cardinal who is of the order of priests. Originally, however, this referred to certain key priests of important churches of the Diocese of Rome, who were recognized as the cardinal priests, the important priests chosen by the pope to advise him in his duties as Bishop of Rome (the Latin cardo means \"hinge\"). Certain clerics in many dioceses at the time, not just that of Rome, were said to be the key personnel—the term gradually became exclusive to Rome to indicate those entrusted with electing the Bishop of Rome, the pope.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 29,
"text": "While the cardinalate has long been expanded beyond the Roman pastoral clergy and Roman Curia, every cardinal priest has a titular church in Rome, though they may be bishops or archbishops elsewhere, just as cardinal bishops were given one of the suburbicarian dioceses around Rome. Pope Paul VI abolished all administrative rights cardinals had with regard to their titular churches, though the cardinal's name and coat of arms are still posted in the church, and they are expected to celebrate Mass and preach there if convenient when they are in Rome.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 30,
"text": "While the number of cardinals was small from the times of the Roman Empire to the Renaissance, and frequently smaller than the number of recognized churches entitled to a cardinal priest, in the 16th century the college expanded markedly. In 1587, Pope Sixtus V sought to arrest this growth by fixing the maximum size of the college at 70, including 50 cardinal priests, about twice the historical number. This limit was respected until 1958, and the list of titular churches modified only on rare occasions, generally when a building fell into disrepair. When Pope John XXIII abolished the limit, he began to add new churches to the list, which Popes Paul VI and John Paul II continued to do. Today there are close to 150 titular churches, out of over 300 churches in Rome.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 31,
"text": "The cardinal who is the longest-serving member of the order of cardinal priests is titled cardinal protopriest. He had certain ceremonial duties in the conclave that have effectively ceased because he would generally have already reached age 80, at which cardinals are barred from the conclave. The current cardinal protopriest is Michael Michai Kitbunchu of Thailand.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 32,
"text": "The cardinal deacons (Latin: cardinales diaconi) are the lowest-ranking cardinals. Cardinals elevated to the diaconal order are either officials of the Roman Curia or priests elevated after their 80th birthday. Bishops with diocesan responsibilities, however, are created cardinal priests.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 33,
"text": "Cardinal deacons derive originally from the seven deacons in the Papal Household who supervised the Church's works in the seven districts of Rome during the early Middle Ages, when church administration was effectively the government of Rome and provided all social services. They came to be called \"cardinal deacons\" by the late eighth century, and they were granted active rights in papal elections and made eligible for the election as pope by the decree of 769.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 34,
"text": "Cardinals elevated to the diaconal order are mainly officials of the Roman Curia holding various posts in the church administration. Their number and influence has varied through the years. While historically predominantly Italian the group has become much more internationally diverse in later years. While in 1939 about half were Italian, by 1994 the number was reduced to one third. Their influence in the election of the pope has been considered important. They are better informed and connected than the dislocated cardinals but their level of unity has been varied. Under the 1587 decree of Pope Sixtus V, which fixed the maximum size of the College of Cardinals, there were 14 cardinal deacons. Later the number increased. As late as 1939 almost half of the cardinals were members of the Curia. Pius XII reduced this percentage to 24 percent. John XXIII brought it back up to 37 percent but Paul VI brought it down to 27 percent where John Paul II maintained this ratio.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 35,
"text": "As of 2005, there were over 50 churches recognized as cardinalatial deaconries, though there were only 30 cardinals of the order of deacons. Cardinal deacons have long enjoyed the right to \"opt for the order of cardinal priests\" (optazione) after they have been cardinal deacons for 10 years. They may on such elevation take a vacant \"title\" (a church allotted to a cardinal priest as the church in Rome with which he is associated) or their diaconal church may be temporarily elevated to a cardinal priest's \"title\" for that occasion. When elevated to cardinal priests, they take their precedence according to the day they were first made cardinal deacons (thus ranking above cardinal priests who were elevated to the college after them, regardless of order).",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 36,
"text": "When not celebrating Mass but still serving a liturgical function, such as the semiannual Urbi et Orbi papal blessing, some Papal Masses and some events at Ecumenical Councils, cardinal deacons can be recognized by the dalmatics they would don with the simple white mitre (so called mitra simplex).",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 37,
"text": "The cardinal protodeacon is the senior cardinal deacon in order of appointment to the College of Cardinals. If he is a cardinal elector and participates in a conclave, he announces a new pope's election and name from the central balcony of St. Peter's Basilica in Vatican City. The protodeacon also bestows the pallium on the new pope and crowns him with the papal tiara, although the crowning has not been celebrated since Pope John Paul I opted for a simpler papal inauguration ceremony in 1978. The current cardinal protodeacon is Renato Raffaele Martino.",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 38,
"text": "* Ceased to be protodeacon upon being raised to the order of cardinal-priest† Was protodeacon at time of death",
"title": "Orders and their chief offices"
},
{
"paragraph_id": 39,
"text": "The Cardinal Camerlengo of the Holy Roman Church, assisted by the Vice-Camerlengo and the other prelates of the office known as the Apostolic Camera, has functions that in essence are limited to a period of sede vacante of the papacy. He is to collate information about the financial situation of all administrations dependent on the Holy See and present the results to the College of Cardinals, as they gather for the papal conclave.",
"title": "Special types of cardinals"
},
{
"paragraph_id": 40,
"text": "Until 1918, any cleric, even one only in minor orders, could be created a cardinal (see \"lay cardinals\", below), but enrolled only in the order of cardinal deacons. For example, in the 16th century, Reginald Pole was a cardinal for 18 years before he was ordained a priest. The 1917 Code of Canon Law mandated that all cardinals, even cardinal deacons, had to be priests, and, in 1962, Pope John XXIII set the norm that all cardinals be consecrated as bishops, even if they are only priests at the time of appointment. As a consequence of these two changes, canon 351 of the 1983 Code of Canon Law requires that a cardinal be at least in the order of priesthood at his appointment, and that those who are not already bishops must receive episcopal consecration. Several cardinals near to or over the age of 80 when appointed have obtained dispensation from the rule of having to be a bishop. These were all appointed cardinal-deacons, but Roberto Tucci and Albert Vanhoye lived long enough to exercise the right of option and be promoted to the rank of cardinal-priest. No cardinal who was not a bishop has participated in a papal conclave since the 1962 rule change. However, as of 21 December 2023 Ángel Fernández Artime, Rector Major of the Salesians, who was created a cardinal by Pope Francis on 30 September 2023, has not been consecrated a bishop and is aged 63, is a cardinal elector.",
"title": "Special types of cardinals"
},
{
"paragraph_id": 41,
"text": "A cardinal who is not a bishop is entitled to wear and use the episcopal vestments and other pontificalia (episcopal regalia: mitre, crozier, zucchetto, pectoral cross, and ring). He has both actual and honorary precedence over archbishops, and bishops who are not cardinals. However, he cannot perform the sacrament of ordination or other rites reserved solely to bishops.",
"title": "Special types of cardinals"
},
{
"paragraph_id": 42,
"text": "At various times, there have been cardinals who had only received first tonsure and minor orders but not yet been ordained as deacons or priests. Though clerics, they were inaccurately called \"lay cardinals\". Teodolfo Mertel was among the last of the lay cardinals. When he died in 1899 he was the last surviving cardinal who was not at least ordained a priest. With the revision of the Code of Canon Law promulgated in 1917 by Pope Benedict XV, only those who are already priests or bishops may be appointed cardinals. Since the time of Pope John XXIII a priest who is appointed a cardinal must be consecrated a bishop, unless he obtains a dispensation.",
"title": "Special types of cardinals"
},
{
"paragraph_id": 43,
"text": "In addition to the named cardinals, the pope may name secret cardinals or cardinals in pectore (Latin for in the breast). During the Western Schism, many cardinals were created by the contending popes. Beginning with the reign of Pope Martin V, cardinals were created without publishing their names until later, a practice termed creati et reservati in pectore. A cardinal named in pectore is known only to the pope. In the modern era, popes have named cardinals in pectore to protect them or their congregations from political reprisals. If conditions change, the pope makes the appointment public. The cardinal in question then ranks in precedence with those made cardinals at the time of his in pectore appointment. If a pope dies before revealing the identity of an in pectore cardinal, the person's status as cardinal expires. The last pope known to have named a cardinal in pectore is Pope John Paul II, who named four, including one whose identity was never revealed.",
"title": "Cardinals in pectore or secret cardinals"
},
{
"paragraph_id": 44,
"text": "When in choir dress, a Latin Church cardinal wears scarlet garments—the blood-like red symbolizes a cardinal's willingness to die for his faith. Excluding the rochet — which is always white—the scarlet garments include the cassock, mozzetta, and biretta (over the usual scarlet zucchetto). The biretta of a cardinal is distinctive not merely for its scarlet color, but also for the fact that it does not have a pompon or tassel on the top as do the birettas of other prelates. Until the 1460s, it was customary for cardinals to wear a violet or blue cape unless granted the privilege of wearing red when acting on papal business. His normal-wear cassock is black but has scarlet piping and a scarlet fascia (sash). Occasionally, a cardinal wears a scarlet ferraiolo which is a cape worn over the shoulders, tied at the neck in a bow by narrow strips of cloth in the front, without any 'trim' or piping on it. It is because of the scarlet color of cardinals' vesture that the bird of the same name has become known as such.",
"title": "Vesture and privileges"
},
{
"paragraph_id": 45,
"text": "Eastern Catholic cardinals continue to wear the normal dress appropriate to their liturgical tradition, though some may line their cassocks with scarlet and wear scarlet fascias, or in some cases, wear Eastern-style cassocks entirely of scarlet.",
"title": "Vesture and privileges"
},
{
"paragraph_id": 46,
"text": "In previous times, at the consistory at which the pope named a new cardinal, he would bestow upon him a distinctive wide-brimmed hat called a galero. This custom was discontinued in 1969 and the investiture now takes place with the scarlet biretta. In ecclesiastical heraldry, however, the scarlet galero is still displayed on the cardinal's coat of arms. Cardinals had the right to display the galero in their cathedral, and when a cardinal died, it would be suspended from the ceiling above his tomb. Some cardinals will still have a galero made, even though it is not officially part of their apparel.",
"title": "Vesture and privileges"
},
{
"paragraph_id": 47,
"text": "To symbolize their bond with the papacy, the pope gives each newly appointed cardinal a gold ring, which is traditionally kissed by Catholics when greeting a cardinal (as with a bishop's episcopal ring). Before the new uniformity imposed by John Paul II, each cardinal was given a ring, the central piece of which was a gem, usually a sapphire, with the pope's stemma engraved on the inside. There is now no gemstone, and the pope chooses the image on the outside: under Pope Benedict XVI it was a modern depiction of the crucifixion of Jesus, with Mary and John to each side. The ring includes the pope's coat of arms on the inside.",
"title": "Vesture and privileges"
},
{
"paragraph_id": 48,
"text": "Cardinals have in canon law a \"privilege of forum\" (i.e., exemption from being judged by ecclesiastical tribunals of ordinary rank): only the pope is competent to judge them in matters subject to ecclesiastical jurisdiction (cases that refer to matters that are spiritual or linked with the spiritual, or with regard to infringement of ecclesiastical laws and whatever contains an element of sin, where culpability must be determined and the appropriate ecclesiastical penalty imposed). The pope either decides the case himself or delegates the decision to a tribunal, usually one of the tribunals or congregations of the Roman Curia. Without such delegation, no ecclesiastical court, even the Roman Rota, is competent to judge a canon law case against a cardinal.",
"title": "Vesture and privileges"
},
{
"paragraph_id": 49,
"text": "Additionally, canon law gives cardinals the faculty of hearing confessions validly and licitly everywhere, whereas other priests and bishops must be granted this faculty and might be restricted in its use by the local bishop.",
"title": "Vesture and privileges"
}
] | A cardinal is a senior member of the clergy of the Catholic Church. Cardinals are created by the pope and typically hold the title for life. Collectively, they constitute the College of Cardinals. The most solemn responsibility of the cardinals is to elect a new pope in a conclave, almost always from among themselves, when the Holy See is vacant. During the period between a pope's death or resignation and the election of his successor, the day-to-day governance of the Holy See is in the hands of the College of Cardinals. The right to participate in a conclave is limited to cardinals who have not reached the age of 80 years by the day the vacancy occurs. In addition, cardinals collectively participate in papal consistories, in which matters of importance to the Church are considered and new cardinals may be created. Cardinals of working age are also appointed to roles overseeing dicasteries of the Roman Curia, the central administration of the Catholic Church. Cardinals are drawn from a variety of backgrounds, being appointed as cardinals in addition to their existing roles within the Church. Most cardinals are bishops and archbishops leading dioceses and archdioceses around the world – often the most prominent diocese or archdiocese in their country. Others are titular bishops who are current or former officials within the Roman Curia. A very small number are priests recognised by the pope for their service to the Church; as canon law requires them to be generally consecrated as bishops before they are made cardinals, but some are granted a papal dispensation. There are no strict criteria for elevation to the College of Cardinals. Since 1917, a potential cardinal must already be at least a priest, but laymen have been cardinals in the past. The selection is entirely up to the pope and tradition is his only guide. As of 5 December 2023, there are 241 serving cardinals, of whom 134 are eligible to vote in a conclave to elect a new pope. | 2001-08-28T18:00:00Z | 2023-12-21T13:44:14Z | [
"Template:Cite news",
"Template:ISBN",
"Template:Holy See",
"Template:Citation needed",
"Template:Main article",
"Template:Further",
"Template:Date",
"Template:Cite press release",
"Template:Catholicism",
"Template:Lang-la",
"Template:Efn",
"Template:Cite book",
"Template:Cite EB1911",
"Template:Catholic Church Hierarchy",
"Template:Age in years",
"Template:Authority control",
"Template:Lit",
"Template:Noteslist",
"Template:Lang",
"Template:Commons category",
"Template:Cardinals of the Catholic Church",
"Template:Wiktla",
"Template:CathEncy",
"Template:Reflist",
"Template:Cite journal",
"Template:Papacy",
"Template:Use dmy dates",
"Template:Main",
"Template:Webarchive",
"Template:Short description",
"Template:Cite web"
] | https://en.wikipedia.org/wiki/Cardinal_(Catholic_Church) |
6,225 | Cantigas de Santa Maria | The Cantigas de Santa Maria (Galician: [kanˈtiɣɐz ðɪ ˈsantɐ maˈɾi.ɐ], Portuguese: [kɐ̃ˈtiɣɐʒ ðɨ ˈsɐ̃tɐ mɐˈɾi.ɐ]; "Canticles of Holy Mary") are 420 poems with musical notation, written in the medieval Galician-Portuguese language during the reign of Alfonso X of Castile El Sabio (1221–1284). Traditionally, they are all attributed to Alfonso, though scholars have since established that the musicians and poets of his court were responsible for most of them, with Alfonso being credited with a few as well.
It is one of the largest collections of monophonic (solo) songs from the Middle Ages and is characterized by the mention of the Virgin Mary in every song, while every tenth song is a hymn.
The Cantigas have survived in four manuscript codices: two at El Escorial, one at Madrid's National Library, and one in Florence, Italy. The E codex from El Escorial is illuminated with colored miniatures showing pairs of musicians playing a wide variety of instruments. The Códice Rico (T) from El Escorial and the one in the Biblioteca Nazionale Centrale of Florence (F) are richly illuminated with narrative vignettes.
The Cantigas are written in the early Medieval Galician variety of Galician-Portuguese, using Galician spelling; this was because of Galician-Portuguese being fashionable as a lyrical language in Castile at the time, as well as Alfonso X having passed part of his early years in Galicia and so probably being a fluent speaker since his childhood.
The Cantigas are a collection of 420 poems, 356 of which are in a narrative format relating to Marian miracles; the rest of them, except an introduction and two prologues, are of songs of praise or involve Marian festivities. The Cantigas depict the Virgin Mary in a very humanized way, often having her play a role in earthly episodes.
The authors are unknown, although several studies have suggested that Galician poet Airas Nunes might have been the author of a large number of the Cantiga poems. King Alfonso X — named as Affonso in the Cantigas — is also believed to be an author of some of them as he refers himself in first person. Support for this theory can be found in the prologue of the Cantigas. Also, many sources credit Alfonso owing to his influence on other works within the poetic tradition, including his introduction on religious song. Although King Alfonso X's authorship is debatable, his influence is not. While the other major works that came out of Alfonso's workshops, including histories and other prose texts, were in Castilian, the Cantigas are in Galician-Portuguese, and reflect the popularity in the Castilian court of other poetic corpuses such as the cantigas d'amigo and cantigas d'amor.
The metrics are extraordinarily diverse: 280 different formats for the 420 Cantigas. The most common are the virelai and the rondeau. The length of the lines varies between two and 24 syllables. The narrative voice in many of the songs describes an erotic relationship, in the troubadour fashion, with the Divine. The music is written in notation which is similar to that used for chant, but also contains some information about the length of the notes. Several transcriptions exist. The Cantigas are frequently recorded and performed by early music groups, and quite a few CDs featuring music from the Cantigas are available.
The Cantigas are preserved in four manuscripts:
E contains the largest number of songs (406 Cantigas, plus the Introduction and the Prologue); it contains 41 carefully detailed miniatures and many illuminated letters. To is the earliest collection and contains 129 songs. Although not illustrated, it is richly decorated with pen flourished initials, and great care has been taken over its construction. The T and F manuscripts are sister volumes. T contains 195 surviving cantigas (8 are missing due to loss of folios) which roughly correspond in order to the first two hundred in E, each song being illustrated with either 6 or 12 miniatures that depict scenes from the cantiga. F follows the same format but has only 111 cantigas, of which 7 have no text, only miniatures. These are basically a subset of those found in the second half of E, but are presented here in a radically different order. F was never finished, and so no music was ever added. Only the empty staves display the intention to add musical notation to the codex at a later date. It is generally thought that the codices were constructed during Alfonso's lifetime, To perhaps in the 1270s, and T/F and E in the early 1280s up until the time of his death in 1284.
The musical forms within the Cantigas, and there are many, are still being studied. There have been many false leads, and there is little beyond pitch value that is very reliable. Mensuration is a particular problem in the Cantigas, and most attempts at determining meaningful rhythmic schemes have tended, with some exceptions, to be unsatisfactory. This remains a lively topic of debate and study. Progress, while on-going, has nevertheless been significant over the course of the last 20 years. | [
{
"paragraph_id": 0,
"text": "The Cantigas de Santa Maria (Galician: [kanˈtiɣɐz ðɪ ˈsantɐ maˈɾi.ɐ], Portuguese: [kɐ̃ˈtiɣɐʒ ðɨ ˈsɐ̃tɐ mɐˈɾi.ɐ]; \"Canticles of Holy Mary\") are 420 poems with musical notation, written in the medieval Galician-Portuguese language during the reign of Alfonso X of Castile El Sabio (1221–1284). Traditionally, they are all attributed to Alfonso, though scholars have since established that the musicians and poets of his court were responsible for most of them, with Alfonso being credited with a few as well.",
"title": ""
},
{
"paragraph_id": 1,
"text": "It is one of the largest collections of monophonic (solo) songs from the Middle Ages and is characterized by the mention of the Virgin Mary in every song, while every tenth song is a hymn.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The Cantigas have survived in four manuscript codices: two at El Escorial, one at Madrid's National Library, and one in Florence, Italy. The E codex from El Escorial is illuminated with colored miniatures showing pairs of musicians playing a wide variety of instruments. The Códice Rico (T) from El Escorial and the one in the Biblioteca Nazionale Centrale of Florence (F) are richly illuminated with narrative vignettes.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The Cantigas are written in the early Medieval Galician variety of Galician-Portuguese, using Galician spelling; this was because of Galician-Portuguese being fashionable as a lyrical language in Castile at the time, as well as Alfonso X having passed part of his early years in Galicia and so probably being a fluent speaker since his childhood.",
"title": "Description"
},
{
"paragraph_id": 4,
"text": "The Cantigas are a collection of 420 poems, 356 of which are in a narrative format relating to Marian miracles; the rest of them, except an introduction and two prologues, are of songs of praise or involve Marian festivities. The Cantigas depict the Virgin Mary in a very humanized way, often having her play a role in earthly episodes.",
"title": "Description"
},
{
"paragraph_id": 5,
"text": "The authors are unknown, although several studies have suggested that Galician poet Airas Nunes might have been the author of a large number of the Cantiga poems. King Alfonso X — named as Affonso in the Cantigas — is also believed to be an author of some of them as he refers himself in first person. Support for this theory can be found in the prologue of the Cantigas. Also, many sources credit Alfonso owing to his influence on other works within the poetic tradition, including his introduction on religious song. Although King Alfonso X's authorship is debatable, his influence is not. While the other major works that came out of Alfonso's workshops, including histories and other prose texts, were in Castilian, the Cantigas are in Galician-Portuguese, and reflect the popularity in the Castilian court of other poetic corpuses such as the cantigas d'amigo and cantigas d'amor.",
"title": "Description"
},
{
"paragraph_id": 6,
"text": "The metrics are extraordinarily diverse: 280 different formats for the 420 Cantigas. The most common are the virelai and the rondeau. The length of the lines varies between two and 24 syllables. The narrative voice in many of the songs describes an erotic relationship, in the troubadour fashion, with the Divine. The music is written in notation which is similar to that used for chant, but also contains some information about the length of the notes. Several transcriptions exist. The Cantigas are frequently recorded and performed by early music groups, and quite a few CDs featuring music from the Cantigas are available.",
"title": "Description"
},
{
"paragraph_id": 7,
"text": "The Cantigas are preserved in four manuscripts:",
"title": "Description"
},
{
"paragraph_id": 8,
"text": "",
"title": "Description"
},
{
"paragraph_id": 9,
"text": "E contains the largest number of songs (406 Cantigas, plus the Introduction and the Prologue); it contains 41 carefully detailed miniatures and many illuminated letters. To is the earliest collection and contains 129 songs. Although not illustrated, it is richly decorated with pen flourished initials, and great care has been taken over its construction. The T and F manuscripts are sister volumes. T contains 195 surviving cantigas (8 are missing due to loss of folios) which roughly correspond in order to the first two hundred in E, each song being illustrated with either 6 or 12 miniatures that depict scenes from the cantiga. F follows the same format but has only 111 cantigas, of which 7 have no text, only miniatures. These are basically a subset of those found in the second half of E, but are presented here in a radically different order. F was never finished, and so no music was ever added. Only the empty staves display the intention to add musical notation to the codex at a later date. It is generally thought that the codices were constructed during Alfonso's lifetime, To perhaps in the 1270s, and T/F and E in the early 1280s up until the time of his death in 1284.",
"title": "Description"
},
{
"paragraph_id": 10,
"text": "The musical forms within the Cantigas, and there are many, are still being studied. There have been many false leads, and there is little beyond pitch value that is very reliable. Mensuration is a particular problem in the Cantigas, and most attempts at determining meaningful rhythmic schemes have tended, with some exceptions, to be unsatisfactory. This remains a lively topic of debate and study. Progress, while on-going, has nevertheless been significant over the course of the last 20 years.",
"title": "Description"
}
] | The Cantigas de Santa Maria are 420 poems with musical notation, written in the medieval Galician-Portuguese language during the reign of Alfonso X of Castile El Sabio (1221–1284). Traditionally, they are all attributed to Alfonso, though scholars have since established that the musicians and poets of his court were responsible for most of them, with Alfonso being credited with a few as well. It is one of the largest collections of monophonic (solo) songs from the Middle Ages and is characterized by the mention of the Virgin Mary in every song, while every tenth song is a hymn. The Cantigas have survived in four manuscript codices: two at El Escorial, one at Madrid's National Library, and one in Florence, Italy. The E codex from El Escorial is illuminated with colored miniatures showing pairs of musicians playing a wide variety of instruments. The Códice Rico (T) from El Escorial and the one in the Biblioteca Nazionale Centrale of Florence (F) are richly illuminated with narrative vignettes. | 2001-08-29T18:26:48Z | 2023-11-28T18:46:00Z | [
"Template:ISBN",
"Template:IPA-pt",
"Template:Authority control",
"Template:IPA-gl",
"Template:Sfn",
"Template:Listen",
"Template:Cite book",
"Template:Commons",
"Template:Short description",
"Template:Reflist",
"Template:Cite journal",
"Template:IMSLP",
"Template:ChoralWiki",
"Template:Italic title"
] | https://en.wikipedia.org/wiki/Cantigas_de_Santa_Maria |
6,226 | Claudio Monteverdi | Claudio Giovanni Antonio Monteverdi (baptized 15 May 1567 – 29 November 1643) was an Italian composer, choirmaster and string player. A composer of both secular and sacred music, and a pioneer in the development of opera, he is considered a crucial transitional figure between the Renaissance and Baroque periods of music history.
Born in Cremona, where he undertook his first musical studies and compositions, Monteverdi developed his career first at the court of Mantua (c. 1590–1613) and then until his death in the Republic of Venice where he was maestro di cappella at the basilica of San Marco. His surviving letters give insight into the life of a professional musician in Italy of the period, including problems of income, patronage and politics.
Much of Monteverdi's output, including many stage works, has been lost. His surviving music includes nine books of madrigals, large-scale religious works, such as his Vespro della Beata Vergine (Vespers for the Blessed Virgin) of 1610, and three complete operas. His opera L'Orfeo (1607) is the earliest of the genre still widely performed; towards the end of his life he wrote works for Venice, including Il ritorno d'Ulisse in patria and L'incoronazione di Poppea.
While he worked extensively in the tradition of earlier Renaissance polyphony, as evidenced in his madrigals, he undertook great developments in form and melody, and began to employ the basso continuo technique, distinctive of the Baroque. No stranger to controversy, he defended his sometimes novel techniques as elements of a seconda pratica, contrasting with the more orthodox earlier style which he termed the prima pratica. Largely forgotten during the eighteenth and much of the nineteenth centuries, his works enjoyed a rediscovery around the beginning of the twentieth century. He is now established both as a significant influence in European musical history and as a composer whose works are regularly performed and recorded.
Monteverdi was baptised in the church of SS Nazaro e Celso, Cremona, on 15 May 1567. The register records his name as "Claudio Zuan Antonio" the son of "Messer Baldasar Mondeverdo". He was the first child of the apothecary Baldassare Monteverdi and his first wife Maddalena (née Zignani); they had married early the previous year. Claudio's brother Giulio Cesare Monteverdi (b. 1573) was also to become a musician; there were two other brothers and two sisters from Baldassare's marriage to Maddalena and his subsequent marriage in 1576 or 1577. Cremona was close to the border of the Republic of Venice, and not far from the lands controlled by the Duchy of Mantua, in both of which states Monteverdi was later to establish his career.
There is no clear record of Monteverdi's early musical training, or evidence that (as is sometimes claimed) he was a member of the Cathedral choir or studied at Cremona University. Monteverdi's first published work, a set of motets, Sacrae cantiunculae (Sacred Songs) for three voices, was issued in Venice in 1582, when he was only fifteen years old. In this, and his other initial publications, he describes himself as the pupil of Marc'Antonio Ingegneri, who was from 1581 (and possibly from 1576) to 1592 the maestro di cappella at Cremona Cathedral. The musicologist Tim Carter deduces that Ingegneri "gave him a solid grounding in counterpoint and composition", and that Monteverdi would also have studied playing instruments of the viol family and singing.
Monteverdi's first publications also give evidence of his connections beyond Cremona, even in his early years. His second published work, Madrigali spirituali (Spiritual Madrigals, 1583), was printed at Brescia. His next works (his first published secular compositions) were sets of five-part madrigals, according to his biographer Paolo Fabbri: "the inevitable proving ground for any composer of the second half of the sixteenth century ... the secular genre par excellence". The first book of madrigals (Venice, 1587) was dedicated to Count Marco Verità of Verona; the second book of madrigals (Venice, 1590) was dedicated to the President of the Senate of Milan, Giacomo Ricardi, for whom he had played the viola da braccio in 1587.
In the dedication of his second book of madrigals, Monteverdi had described himself as a player of the vivuola (which could mean either viola da gamba or viola da braccio). In 1590 or 1591 he entered the service of Duke Vincenzo I Gonzaga of Mantua; he recalled in his dedication to the Duke of his third book of madrigals (Venice, 1592) that "the most noble exercise of the vivuola opened to me the fortunate way into your service." In the same dedication he compares his instrumental playing to "flowers" and his compositions as "fruit" which as it matures "can more worthily and more perfectly serve you", indicating his intentions to establish himself as a composer.
Duke Vincenzo was keen to establish his court as a musical centre, and sought to recruit leading musicians. When Monteverdi arrived in Mantua, the maestro di capella at the court was the Flemish musician Giaches de Wert. Other notable musicians at the court during this period included the composer and violinist Salomone Rossi, Rossi's sister, the singer Madama Europa, and Francesco Rasi. Monteverdi married the court singer Claudia de Cattaneis in 1599; they were to have three children, two sons (Francesco, b. 1601 and Massimiliano, b. 1604), and a daughter who died soon after birth in 1603. Monteverdi's brother Giulio Cesare joined the court musicians in 1602.
When Wert died in 1596, his post was given to Benedetto Pallavicino, but Monteverdi was clearly highly regarded by Vincenzo and accompanied him on his military campaigns in Hungary (1595) and also on a visit to Flanders in 1599. Here at the town of Spa he is reported by his brother Giulio Cesare as encountering, and bringing back to Italy, the canto alla francese. (The meaning of this, literally "song in the French style", is debatable, but may refer to the French-influenced poetry of Gabriello Chiabrera, some of which was set by Monteverdi in his Scherzi musicali, and which departs from the traditional Italian style of lines of 9 or 11 syllables). Monteverdi may possibly have been a member of Vincenzo's entourage at Florence in 1600 for the marriage of Maria de' Medici and Henry IV of France, at which celebrations Jacopo Peri's opera Euridice (the earliest surviving opera) was premiered. On the death of Pallavicino in 1601, Monteverdi was confirmed as the new maestro di capella.
At the turn of the 17th century, Monteverdi found himself the target of musical controversy. The influential Bolognese theorist Giovanni Maria Artusi attacked Monteverdi's music (without naming the composer) in his work L'Artusi, overo Delle imperfettioni della moderna musica (Artusi, or On the imperfections of modern music) of 1600, followed by a sequel in 1603. Artusi cited extracts from Monteverdi's works not yet published (they later formed parts of his fourth and fifth books of madrigals of 1603 and 1605), condemning their use of harmony and their innovations in use of musical modes, compared to orthodox polyphonic practice of the sixteenth century. Artusi attempted to correspond with Monteverdi on these issues; the composer refused to respond, but found a champion in a pseudonymous supporter, "L'Ottuso Academico" ("The Obtuse Academic"). Eventually Monteverdi replied in the preface to the fifth book of madrigals that his duties at court prevented him from a detailed reply; but in a note to "the studious reader", he claimed that he would shortly publish a response, Seconda Pratica, overo Perfettione della Moderna Musica (The Second Style, or Perfection of Modern Music). This work never appeared, but a later publication by Claudio's brother Giulio Cesare made it clear that the seconda pratica which Monteverdi defended was not seen by him as a radical change or his own invention, but was an evolution from previous styles (prima pratica) which was complementary to them.
This debate seems in any case to have raised the composer's profile, leading to reprints of his earlier books of madrigals. Some of his madrigals were published in Copenhagen in 1605 and 1606, and the poet Tommaso Stigliani (1573–1651) published a eulogy of him in his 1605 poem "O sirene de' fiumi". The composer of madrigal comedies and theorist Adriano Banchieri wrote in 1609: "I must not neglect to mention the most noble of composers, Monteverdi ... his expressive qualities are truly deserving of the highest commendation, and we find in them countless examples of matchless declamation ... enhanced by comparable harmonies." The modern music historian Massimo Ossi has placed the Artusi issue in the context of Monteverdi's artistic development: "If the controversy seems to define Monteverdi's historical position, it also seems to have been about stylistic developments that by 1600 Monteverdi had already outgrown".
The non-appearance of Monteverdi's promised explanatory treatise may have been a deliberate ploy, since by 1608, by Monteverdi's reckoning, Artusi had become fully reconciled to modern trends in music, and the seconda pratica was by then well established; Monteverdi had no need to revisit the issue. On the other hand, letters to Giovanni Battista Doni of 1632 show that Monteverdi was still preparing a defence of the seconda practica, in a treatise entitled Melodia; he may still have been working on this at the time of his death ten years later.
In 1606 Vincenzo's heir Francesco commissioned from Monteverdi the opera L'Orfeo, to a libretto by Alessandro Striggio, for the Carnival season of 1607. It was given two performances in February and March 1607; the singers included, in the title role, Rasi, who had sung in the first performance of Euridice witnessed by Vincenzo in 1600. This was followed in 1608 by the opera L'Arianna (libretto by Ottavio Rinuccini), intended for the celebration of the marriage of Francesco to Margherita of Savoy. All the music for this opera is lost apart from Ariadne's Lament, which became extremely popular. To this period also belongs the ballet entertainment Il ballo delle ingrate.
The strain of the hard work Monteverdi had been putting into these and other compositions was exacerbated by personal tragedies. His wife died in September 1607 and the young singer Caterina Martinelli, intended for the title role of Arianna, died of smallpox in March 1608. Monteverdi also resented his increasingly poor financial treatment by the Gonzagas. He retired to Cremona in 1608 to convalesce, and wrote a bitter letter to Vincenzo's minister Annibale Chieppio in November of that year seeking (unsuccessfully) "an honourable dismissal". Although the Duke increased Monteverdi's salary and pension, and Monteverdi returned to continue his work at the court, he began to seek patronage elsewhere. After publishing his Vespers in 1610, which were dedicated to Pope Paul V, he visited Rome, ostensibly hoping to place his son Francesco at a seminary, but apparently also seeking alternative employment. In the same year he may also have visited Venice, where a large collection of his church music was being printed, with a similar intention.
Duke Vincenzo died on 18 February 1612. When Francesco succeeded him, court intrigues and cost-cutting led to the dismissal of Monteverdi and his brother Giulio Cesare, who both returned, almost penniless, to Cremona. Despite Francesco's own death from smallpox in December 1612, Monteverdi was unable to return to favour with his successor, his brother Cardinal Ferdinando Gonzaga. In 1613, following the death of Giulio Cesare Martinengo, Monteverdi auditioned for his post as maestro at the basilica of San Marco in Venice, for which he submitted music for a Mass. He was appointed in August 1613, and given 50 ducats for his expenses (of which he was robbed, together with his other belongings, by highwaymen at Sanguinetto on his return to Cremona).
Martinengo had been ill for some time before his death and had left the music of San Marco in a fragile state. The choir had been neglected and the administration overlooked. When Monteverdi arrived to take up his post, his principal responsibility was to recruit, train, discipline and manage the musicians of San Marco (the capella), who amounted to about 30 singers and six instrumentalists; the numbers could be increased for major events. Among the recruits to the choir was Francesco Cavalli, who joined in 1616 at the age of 14; he was to remain connected with San Marco throughout his life, and was to develop a close association with Monteverdi. Monteverdi also sought to expand the repertory, including not only the traditional a cappella repertoire of Roman and Flemish composers, but also examples of the modern style which he favoured, including the use of continuo and other instruments. Apart from this he was of course expected to compose music for all the major feasts of the church. This included a new mass each year for Holy Cross Day and Christmas Eve, cantatas in honour of the Venetian Doge, and numerous other works (many of which are lost). Monteverdi was also free to obtain income by providing music for other Venetian churches and for other patrons, and was frequently commissioned to provide music for state banquets. The Procurators of San Marco, to whom Monteverdi was directly responsible, showed their satisfaction with his work in 1616 by raising his annual salary from 300 ducats to 400.
The relative freedom which the Republic of Venice afforded him, compared to the problems of court politics in Mantua, are reflected in Monteverdi's letters to Striggio, particularly his letter of 13 March 1620, when he rejects an invitation to return to Mantua, extolling his present position and finances in Venice, and referring to the pension which Mantua still owes him. Nonetheless, remaining a Mantuan citizen, he accepted commissions from the new Duke Ferdinando, who had formally renounced his position as Cardinal in 1616 to take on the duties of state. These included the balli Tirsi e Clori (1616) and Apollo (1620), an opera Andromeda (1620) and an intermedio, Le nozze di Tetide, for the marriage of Ferdinando with Caterina de' Medici (1617). Most of these compositions were extensively delayed in creation – partly, as shown by surviving correspondence, through the composer's unwillingness to prioritise them, and partly because of constant changes in the court's requirements. They are now lost, apart from Tirsi e Clori, which was included in the seventh book of madrigals (published 1619) and dedicated to the Duchess Caterina, for which the composer received a pearl necklace from the Duchess. A subsequent major commission, the opera La finta pazza Licori, to a libretto by Giulio Strozzi, was completed for Fernando's successor Vincenzo II, who succeeded to the dukedom in 1626. Because of the latter's illness (he died in 1627), it was never performed, and it is now also lost.
Monteverdi also received commissions from other Italian states and from their communities in Venice. These included, for the Milanese community in 1620, music for the Feast of St. Charles Borromeo, and for the Florentine community a Requiem Mass for Cosimo II de' Medici (1621). Monteverdi acted on behalf of Paolo Giordano II, Duke of Bracciano, to arrange publication of works by the Cremona musician Francesco Petratti. Among Monteverdi's private Venetian patrons was the nobleman Girolamo Mocenigo, at whose home was premiered in 1624 the dramatic entertainment Il combattimento di Tancredi e Clorinda based on an episode from Torquato Tasso's La Gerusalemme liberata. In 1627 Monteverdi received a major commission from Odoardo Farnese, Duke of Parma, for a series of works, and gained leave from the Procurators to spend time there during 1627 and 1628.
Monteverdi's musical direction received the attention of foreign visitors. The Dutch diplomat and musician Constantijn Huygens, attending a Vespers service at the church of SS. Giovanni e Lucia, wrote that he "heard the most perfect music I had ever heard in my life. It was directed by the most famous Claudio Monteverdi ... who was also the composer and was accompanied by four theorbos, two cornettos, two bassoons, one basso de viola of huge size, organs and other instruments ...". Monteverdi wrote a mass, and provided other musical entertainment, for the visit to Venice in 1625 of the Crown Prince Władysław of Poland, who may have sought to revive attempts made a few years previously to lure Monteverdi to Warsaw. He also provided chamber music for Wolfgang Wilhelm, Count Palatine of Neuburg, when the latter was paying an incognito visit to Venice in July 1625.
Correspondence of Monteverdi in 1625 and 1626 with the Mantuan courtier Ercole Marigliani reveals an interest in alchemy, which apparently Monteverdi had taken up as a hobby. He discusses experiments to transform lead into gold, the problems of obtaining mercury, and mentions commissioning special vessels for his experiments from the glassworks at Murano.
Despite his generally satisfactory situation in Venice, Monteverdi experienced personal problems from time to time. He was on one occasion – probably because of his wide network of contacts – the subject of an anonymous denunciation to the Venetian authorities alleging that he supported the Habsburgs. He was also subject to anxieties about his children. His son Francesco, while a student of law at Padua in 1619, was spending in Monteverdi's opinion too much time with music, and he, therefore, moved him to the University of Bologna. This did not have the required result, and it seems that Monteverdi resigned himself to Francesco having a musical career – he joined the choir of San Marco in 1623. His other son Massimiliano, who graduated in medicine, was arrested by the Inquisition in Mantua in 1627 for reading forbidden literature. Monteverdi was obliged to sell the necklace he had received from Duchess Caterina to pay for his son's (eventually successful) defence. Monteverdi wrote at the time to Striggio seeking his help, and fearing that Massimiliano might be subject to torture; it seems that Striggio's intervention was helpful. Money worries at this time also led Monteverdi to visit Cremona to secure for himself a church canonry.
A series of disturbing events troubled Monteverdi's world in the period around 1630. Mantua was invaded by Habsburg armies in 1630, who besieged the plague-stricken town, and after its fall in July looted its treasures, and dispersed the artistic community. The plague was carried to Mantua's ally Venice by an embassy led by Monteverdi's confidante Striggio, and over a period of 16 months led to over 45,000 deaths, leaving Venice's population in 1633 at just above 100,000, the lowest level for about 150 years. Among the plague victims was Monteverdi's assistant at San Marco, and a notable composer in his own right, Alessandro Grandi. The plague and the after-effects of war had an inevitable deleterious effect on the economy and artistic life of Venice. Monteverdi's younger brother Giulio Cesare also died at this time, probably from the plague.
By this time Monteverdi was in his sixties, and his rate of composition seems to have slowed down. He had written a setting of Strozzi's Proserpina rapita (The Abduction of Proserpina), now lost except for one vocal trio, for a Mocenigo wedding in 1630, and produced a Mass for deliverance from the plague for San Marco which was performed in November 1631. His set of Scherzi musicali was published in Venice in 1632. In 1631, Monteverdi was admitted to the tonsure, and was ordained deacon, and later priest, in 1632. Although these ceremonies took place in Venice, he was nominated as a member of Diocese of Cremona; this may imply that he intended to retire there.
The opening of the opera house of San Cassiano in 1637, the first public opera house in Europe, stimulated the city's musical life and coincided with a new burst of the composer's activity. The year 1638 saw the publication of Monteverdi's eighth book of madrigals and a revision of the Ballo delle ingrate. The eighth book contains a ballo, "Volgendi il ciel", which may have been composed for the Holy Roman Emperor, Ferdinand III, to whom the book is dedicated. The years 1640–1641 saw the publication of the extensive collection of church music, Selva morale e spirituale. Among other commissions, Monteverdi wrote music in 1637 and 1638 for Strozzi's "Accademia degli Unisoni" in Venice, and in 1641 a ballet, La vittoria d'Amore, for the court of Piacenza.
Monteverdi was still not entirely free from his responsibilities for the musicians at San Marco. He wrote to complain about one of his singers to the Procurators, on 9 June 1637: "I, Claudio Monteverdi ... come humbly ... to set forth to you how Domenicato Aldegati ... a bass, yesterday morning ... at the time of the greatest concourse of people ... spoke these exact words ...'The Director of Music comes from a brood of cut-throat bastards, a thieving, fucking, he-goat ... and I shit on him and whoever protects him ...'".
Monteverdi's contribution to opera at this period is notable. He revised his earlier opera L'Arianna in 1640 and wrote three new works for the commercial stage, Il ritorno d'Ulisse in patria (The Return of Ulysses to his Homeland, 1640, first performed in Bologna with Venetian singers), Le nozze d'Enea e Lavinia (The Marriage of Aeneas and Lavinia, 1641, music now lost), and L'incoronazione di Poppea (The Coronation of Poppea, 1643). The introduction to the printed scenario of Le nozze d'Enea, by an unknown author, acknowledges that Monteverdi is to be credited for the rebirth of theatrical music and that "he will be sighed for in later ages, for his compositions will surely outlive the ravages of time."
In his last surviving letter (20 August 1643), Monteverdi, already ill, was still hoping for the settlement of the long-disputed pension from Mantua, and asked the Doge of Venice to intervene on his behalf. He died in Venice on 29 November 1643, after paying a brief visit to Cremona, and is buried in the Church of the Frari. He was survived by his sons; Masimilliano died in 1661, Francesco after 1677.
There is a consensus among music historians that a period extending from the mid-15th century to around 1625, characterised in Lewis Lockwood's phrase by "substantial unity of outlook and language", should be identified as the period of "Renaissance music". Musical literature has also defined the succeeding period (covering music from approximately 1580 to 1750) as the era of "Baroque music". It is in the late-16th to early-17th-century overlap of these periods that much of Monteverdi's creativity flourished; he stands as a transitional figure between the Renaissance and the Baroque.
In the Renaissance era, music had developed as a formal discipline, a "pure science of relationships" in the words of Lockwood. In the Baroque era it became a form of aesthetic expression, increasingly used to adorn religious, social and festive celebrations in which, in accordance with Plato's ideal, the music was subordinated to the text. Solo singing with instrumental accompaniment, or monody, acquired greater significance towards the end of the 16th century, replacing polyphony as the principal means of dramatic music expression. This was the changing world in which Monteverdi was active. Percy Scholes in his Oxford Companion to Music describes the "new music" thus: "[Composers] discarded the choral polyphony of the madrigal style as barbaric, and set dialogue or soliloquy for single voices, imitating more or less the inflexions of speech and accompanying the voice by playing mere supporting chords. Short choruses were interspersed, but they too were homophonic rather than polyphonic."
Ingegneri, Monteverdi's first tutor, was a master of the musica reservata vocal style, which involved the use of chromatic progressions and word-painting; Monteverdi's early compositions were grounded in this style. Ingegneri was a traditional Renaissance composer, "something of an anachronism", according to Arnold, but Monteverdi also studied the work of more "modern" composers such as Luca Marenzio, Luzzasco Luzzaschi, and a little later, Giaches de Wert, from whom he would learn the art of expressing passion. He was a precocious and productive student, as indicated by his youthful publications of 1582–83. Mark Ringer writes that "these teenaged efforts reveal palpable ambition matched with a convincing mastery of contemporary style", but at this stage they display their creator's competence rather than any striking originality. Geoffrey Chew classifies them as "not in the most modern vein for the period", acceptable but out-of-date. Chew rates the Canzonette collection of 1584 much more highly than the earlier juvenilia: "These brief three-voice pieces draw on the airy, modern style of the villanellas of Marenzio, [drawing on] a substantial vocabulary of text-related madrigalisms".
The canzonetta form was much used by composers of the day as a technical exercise, and is a prominent element in Monteverdi's first book of madrigals published in 1587. In this book, the playful, pastoral settings again reflect the style of Marenzio, while Luzzaschi's influence is evident in Monteverdi's use of dissonance. The second book (1590) begins with a setting modelled on Marenzio of a modern verse, Torquato Tasso's "Non si levav' ancor", and concludes with a text from 50 years earlier: Pietro Bembo's "Cantai un tempo". Monteverdi set the latter to music in an archaic style reminiscent of the long-dead Cipriano de Rore. Between them is "Ecco mormorar l'onde", strongly influenced by de Wert and hailed by Chew as the great masterpiece of the second book.
A thread common throughout these early works is Monteverdi's use of the technique of imitatio, a general practice among composers of the period whereby material from earlier or contemporary composers was used as models for their own work. Monteverdi continued to use this procedure well beyond his apprentice years, a factor that in some critics' eyes has compromised his reputation for originality.
Monteverdi's first fifteen years of service in Mantua are bracketed by his publications of the third book of madrigals in 1592 and the fourth and fifth books in 1603 and 1605. Between 1592 and 1603 he made minor contributions to other anthologies. How much he composed in this period is a matter of conjecture; his many duties in the Mantuan court may have limited his opportunities, but several of the madrigals that he published in the fourth and fifth books were written and performed during the 1590s, some figuring prominently in the Artusi controversy.
The third book shows strongly the increased influence of Wert, by that time Monteverdi's direct superior as maestro de capella at Mantua. Two poets dominate the collection: Tasso, whose lyrical poetry had figured prominently in the second book but is here represented through the more epic, heroic verses from Gerusalemme liberata, and Giovanni Battista Guarini, whose verses had appeared sporadically in Monteverdi's earlier publications, but form around half of the contents of the third book. Wert's influence is reflected in Monteverdi's forthrightly modern approach, and his expressive and chromatic settings of Tasso's verses. Of the Guarini settings, Chew writes: "The epigrammatic style ... closely matches a poetic and musical ideal of the period ... [and] often depends on strong, final cadential progressions, with or without the intensification provided by chains of suspended dissonances". Chew cites the setting of "Stracciami pur il core" as "a prime example of Monteverdi's irregular dissonance practice". Tasso and Guarini were both regular visitors to the Mantuan court; Monteverdi's association with them and his absorption of their ideas may have helped lay the foundations of his own approach to the musical dramas that he would create a decade later.
As the 1590s progressed, Monteverdi moved closer towards the form that he would identify in due course as the seconda pratica. Claude V. Palisca quotes the madrigal Ohimè, se tanto amate, published in the fourth book but written before 1600 – it is among the works attacked by Artusi – as a typical example of the composer's developing powers of invention. In this madrigal Monteverdi again departs from the established practice in the use of dissonance, by means of a vocal ornament Palisca describes as échappé. Monteverdi's daring use of this device is, says Palisca, "like a forbidden pleasure". In this and in other settings the poet's images were supreme, even at the expense of musical consistency.
The fourth book includes madrigals to which Artusi objected on the grounds of their "modernism". However, Ossi describes it as "an anthology of disparate works firmly rooted in the 16th century", closer in nature to the third book than to the fifth. Besides Tasso and Guarini, Monteverdi set to music verses by Rinuccini, Maurizio Moro (Sì ch'io vorrei morire) and Ridolfo Arlotti (Luci serene e chiare). There is evidence of the composer's familiarity with the works of Carlo Gesualdo, and with composers of the school of Ferrara such as Luzzaschi; the book was dedicated to a Ferrarese musical society, the Accademici Intrepidi.
The fifth book looks more to the future; for example, Monteverdi employs the concertato style with basso continuo (a device that was to become a typical feature in the emergent Baroque era), and includes a sinfonia (instrumental interlude) in the final piece. He presents his music through complex counterpoint and daring harmonies, although at times combining the expressive possibilities of the new music with traditional polyphony.
Aquilino Coppini drew much of the music for his sacred contrafacta of 1608 from Monteverdi's 3rd, 4th and 5th books of madrigals. In writing to a friend in 1609 Coppini commented that Monteverdi's pieces "require, during their performance, more flexible rests and bars that are not strictly regular, now pressing forward or abandoning themselves to slowing down [...] In them there is a truly wondrous capacity for moving the affections".
In Monteverdi's final five years' service in Mantua he completed the operas L'Orfeo (1607) and L'Arianna (1608), and wrote quantities of sacred music, including the Messa in illo tempore (1610) and also the collection known as Vespro della Beata Vergine which is often referred to as "Monteverdi's Vespers" (1610). He also published Scherzi musicale a tre voci (1607), settings of verses composed since 1599 and dedicated to the Gonzaga heir, Francesco. The vocal trio in the Scherzi comprises two sopranos and a bass, accompanied by simple instrumental ritornellos. According to Bowers the music "reflected the modesty of the prince's resources; it was, nevertheless, the earliest publication to associate voices and instruments in this particular way".
The opera opens with a brief trumpet toccata. The prologue of La musica (a figure representing music) is introduced with a ritornello by the strings, repeated often to represent the "power of music" – one of the earliest examples of an operatic leitmotif. Act 1 presents a pastoral idyll, the buoyant mood of which continues into Act 2. The confusion and grief which follow the news of Euridice's death are musically reflected by harsh dissonances and the juxtaposition of keys. The music remains in this vein until the act ends with the consoling sounds of the ritornello.
Act 3 is dominated by Orfeo's aria "Possente spirto e formidabil nume" by which he attempts to persuade Caronte to allow him to enter Hades. Monteverdi's vocal embellishments and virtuoso accompaniment provide what Tim Carter has described as "one of the most compelling visual and aural representations" in early opera. In Act 4 the warmth of Proserpina's singing on behalf of Orfeo is retained until Orfeo fatally "looks back". The brief final act, which sees Orfeo's rescue and metamorphosis, is framed by the final appearance of the ritornello and by a lively moresca that brings the audience back to their everyday world.
Throughout the opera Monteverdi makes innovative use of polyphony, extending the rules beyond the conventions which composers normally observed in fidelity to Palestrina. He combines elements of the traditional 16th-century madrigal with the new monodic style where the text dominates the music and sinfonias and instrumental ritornellos illustrate the action.
The music for this opera is lost except for the Lamento d'Arianna, which was published in the sixth book in 1614 as a five-voice madrigal; a separate monodic version was published in 1623. In its operatic context the lament depicts Arianna's various emotional reactions to her abandonment: sorrow, anger, fear, self-pity, desolation and a sense of futility. Throughout, indignation and anger are punctuated by tenderness, until a descending line brings the piece to a quiet conclusion.
The musicologist Suzanne Cusick writes that Monteverdi "creat[ed] the lament as a recognizable genre of vocal chamber music and as a standard scene in opera ... that would become crucial, almost genre-defining, to the full-scale public operas of 17th-century Venice". Cusick observes how Monteverdi is able to match in music the "rhetorical and syntactical gestures" in the text of Ottavio Rinuccini. The opening repeated words "Lasciatemi morire" (Let me die) are accompanied by a dominant seventh chord which Ringer describes as "an unforgettable chromatic stab of pain". Ringer suggests that the lament defines Monteverdi's innovative creativity in a manner similar to that in which the Prelude and the Liebestod in Tristan und Isolde announced Wagner's discovery of new expressive frontiers.
Rinuccini's full libretto, which has survived, was set in modern times by Alexander Goehr (Arianna, 1995), including a version of Monteverdi's Lament.
The Vespro della Beata Vergine, Monteverdi's first published sacred music since the Madrigali spirituali of 1583, consists of 14 components: an introductory versicle and response, five psalms interspersed with five "sacred concertos" (Monteverdi's term), a hymn, and two Magnificat settings. Collectively these pieces fulfil the requirements for a Vespers service on any feast day of the Virgin. Monteverdi employs many musical styles; the more traditional features, such as cantus firmus, falsobordone and Venetian canzone, are mixed with the latest madrigal style, including echo effects and chains of dissonances. Some of the musical features used are reminiscent of L'Orfeo, written slightly earlier for similar instrumental and vocal forces.
In this work the "sacred concertos" fulfil the role of the antiphons which divide the psalms in regular Vespers services. Their non-liturgical character has led writers to question whether they should be within the service, or indeed whether this was Monteverdi's intention. In some versions of Monteverdi's Vespers (for example, those of Denis Stevens) the concertos are replaced with antiphons associated with the Virgin, although John Whenham in his analysis of the work argues that the collection as a whole should be regarded as a single liturgical and artistic entity.
All the psalms, and the Magnificat, are based on melodically limited and repetitious Gregorian chant psalm tones, around which Monteverdi builds a range of innovative textures. This concertato style challenges the traditional cantus firmus, and is most evident in the "Sonata sopra Sancta Maria", written for eight string and wind instruments plus basso continuo, and a single soprano voice. Monteverdi uses modern rhythms, frequent metre changes and constantly varying textures; yet, according to John Eliot Gardiner, "for all the virtuosity of its instrumental writing and the evident care which has gone into the combinations of timbre", Monteverdi's chief concern was resolving the proper combination of words and music.
The actual musical ingredients of the Vespers were not novel to Mantua – concertato had been used by Lodovico Grossi da Viadana, a former choirmaster at the cathedral of Mantua, while the Sonata sopra had been anticipated by Archangelo Crotti in his Sancta Maria published in 1608. It is, writes Denis Arnold, Monteverdi's mixture of the various elements that makes the music unique. Arnold adds that the Vespers achieved fame and popularity only after their 20th-century rediscovery; they were not particularly regarded in Monteverdi's time.
During his years in Venice Monteverdi published his sixth (1614), seventh (1619) and eighth (1638) books of madrigals. The sixth book consists of works written before the composer's departure from Mantua. Hans Redlich sees it as a transitional work, containing Monteverdi's last madrigal compositions in the manner of the prima pratica, together with music which is typical of the new style of expression which Monteverdi had displayed in the dramatic works of 1607–08. The central theme of the collection is loss; the best-known work is the five-voice version of the Lamento d'Arianna, which, says Massimo Ossi, gives "an object lesson in the close relationship between monodic recitative and counterpoint". The book contains Monteverdi's first settings of verses by Giambattista Marino, and two settings of Petrarch which Ossi considers the most extraordinary pieces in the volume, providing some "stunning musical moments".
While Monteverdi had looked backwards in the sixth book, he moved forward in the seventh book from the traditional concept of the madrigal, and from monody, in favour of chamber duets. There are exceptions, such the two solo lettere amorose (love letters) "Se i languidi miei sguardi" and "Se pur destina e vole", written to be performed genere rapresentativo – acted as well as sung. Of the duets which are the main features of the volume, Chew highlights "Ohimé, dov'è il mio ben, dov'è il mio core", a romanesca in which two high voices express dissonances above a repetitive bass pattern. The book also contains large-scale ensemble works, and the ballet Tirsi e Clori. This was the height of Monteverdi's "Marino period"; six of the pieces in the book are settings of the poet's verses. As Carter puts it, Monteverdi "embraced Marino's madrigalian kisses and love-bites with ... the enthusiasm typical of the period". Some commentators have opined that the composer should have had better poetic taste.
The eighth book, subtitled Madrigali guerrieri, et amorosi ... ("Madrigals of war and love") is structured in two symmetrical halves, one for "war" and one for "love". Each half begins with a six-voice setting, followed by an equally large-scale Petrarch setting, then a series of duets mainly for tenor voices, and concludes with a theatrical number and a final ballet. The "war" half contains several items written as tributes to the emperor Ferdinand III, who had succeeded to the Habsburg throne in 1637. Many of Monteverdi's familiar poets – Strozzi, Rinuccini, Tasso, Marino, Guarini – are represented in the settings.
It is difficult to gauge when many of the pieces were composed, although the ballet Mascherata dell' ingrate that ends the book dates back to 1608 and the celebration of the Gonzaga-Savoy marriage. The Combattimento di Tancredi e Clorinda, centrepiece of the "war" settings, had been written and performed in Venice in 1624; on its publication in the eighth book, Monteverdi explicitly linked it to his concept of concitato genera (otherwise stile concitato – "aroused style") that would "fittingly imitate the utterance and the accents of a brave man who is engaged in warfare", and implied that since he had originated this style, others had begun to copy it. The work employed for the first time instructions for the use of pizzicato string chords, and also evocations of fanfares and other sounds of combat.
The critic Andrew Clements describes the eighth book as "a statement of artistic principles and compositional authority", in which Monteverdi "shaped and expanded the madrigal form to accommodate what he wanted to do ... the pieces collected in Book Eight make up a treasury of what music in the first half the 17th century could possibly express."
During this period of his Venetian residency, Monteverdi composed quantities of sacred music. Numerous motets and other short works were included in anthologies by local publishers such as Giulio Cesare Bianchi (a former student of Monteverdi) and Lorenzo Calvi, and others were published elsewhere in Italy and Austria. The range of styles in the motets is broad, from simple strophic arias with string accompaniment to full-scale declamations with an alleluia finale.
Monteverdi retained emotional and political attachments to the Mantuan court and wrote for it, or undertook to write, large amounts of stage music including at least four operas. The ballet Tirsi e Clori survives through its inclusion in the seventh book, but the rest of the Mantuan dramatic music is lost. Many of the missing manuscripts may have disappeared in the wars that overcame Mantua in 1630. The most significant aspect of their loss, according to Carter, is the extent to which they might have provided musical links between Monteverdi's early Mantuan operas and those he wrote in Venice after 1638: "Without these links ... it is hard to a produce a coherent account of his development as a composer for the stage". Likewise, Janet Beat regrets that the 30-year gap hampers the study of how opera orchestration developed during those critical early years.
Apart from the madrigal books, Monteverdi's only published collection during this period was the volume of Scherzi musicale in 1632. For unknown reasons, the composer's name does not appear on the inscription, the dedication being signed by the Venetian printer Bartolomeo Magni; Carter surmises that the recently ordained Monteverdi may have wished to keep his distance from this secular collection. It mixes strophic continuo songs for solo voice with more complex works which employ continuous variation over repeated bass patterns. Chew selects the chaconne for two tenors, Zefiro torna e di soavi accenti, as the outstanding item in the collection: "[T]he greater part of this piece consists of repetitions of a bass pattern which ensures tonal unity of a simple kind, owing to its being framed as a simple cadence in a G major tonal type: over these repetitions, inventive variations unfold in virtuoso passage-work".
Main articles: Il ritorno d'Ulisse in patria; L'incoronazione di Poppea; Selva morale e spirituale
The last years of Monteverdi's life were much occupied with opera for the Venetian stage. Richard Taruskin, in his Oxford History of Western Music, gave his chapter on this topic the title "Opera from Monteverdi to Monteverdi." This wording, originally proposed humorously by the Italian music historian Nino Pirrotta, is interpreted seriously by Taruskin as indicating that Monteverdi is significantly responsible for the transformation of the opera genre from a private entertainment of the nobility (as with Orfeo in 1607), to what became a major commercial genre, as exemplified by his opera L'incoronazione di Poppea (1643). His two surviving operatic works of this period, Il ritorno d'Ulisse in patria and L'incoronazione are held by Arnold to be the first "modern" operas; Il ritorno is the first Venetian opera to depart from what Ellen Rosand terms "the mythological pastoral". However, David Johnson in the North American Review warns audiences not to expect immediate affinity with Mozart, Verdi or Puccini: "You have to submit yourself to a much slower pace, to a much more chaste conception of melody, to a vocal style that is at first merely like dry declamation and only on repeated hearings begins to assume an extraordinary eloquence."
Il ritorno, says Carter, is clearly influenced by Monteverdi's earlier works. Penelope's lament in Act I is close in character to the lament from L'Arianna, while the martial episodes recall Il combattimento. Stile concitato is prominent in the fight scenes and in the slaying of Penelope's suitors. In L'incoronazione, Monteverdi represents moods and situations by specific musical devices: triple metre stands for the language of love; arpeggios demonstrate conflict; stile concitato represents rage. There is continuing debate about how much of the extant L'incoronazione music is Monteverdi's original, and how much is the work of others (there are, for instance, traces of music by Francesco Cavalli).
The Selva morale e spirituale of 1641, and the posthumous Messa et salmi published in 1650 (which was edited by Cavalli), are selections of the sacred music that Monteverdi wrote for San Marco during his 30-year tenure – much else was likely written but not published. The Selva morale volume opens with a series of madrigal settings on moral texts, dwelling on themes such as "the transitory nature of love, earthly rank and achievement, even existence itself". They are followed by a Mass in conservative style (stile antico), the high point of which is an extended seven-voice "Gloria". Scholars believe that this might have been written to celebrate the end of the 1631 plague. The rest of the volume is made up of numerous psalm settings, two Magnificats and three Salve Reginas. The Messa et salmi volume includes a stile antico Mass for four voices, a polyphonic setting of the psalm Laetatus Sum, and a version of the Litany of Lareto that Monteverdi had originally published in 1620.
The posthumous ninth book of madrigals was published in 1651, a miscellany dating back to the early 1630s, some items being repeats of previously published pieces, such as the popular duet O sia tranquillo il mare from 1638. The book includes a trio for three sopranos, "Come dolce oggi l'auretta", which is the only surviving music from the 1630 lost opera Proserpina rapita.
In his lifetime Monteverdi enjoyed considerable status among musicians and the public. This is evidenced by the scale of his funeral rites: "[W]ith truly royal pomp a catafalque was erected in the Chiesa de Padrini Minori de Frari, decorated all in mourning, but surrounded with so many candles that the church resembled a night sky luminous with stars". This glorification was transitory; Carter writes that in Monteverdi's day, music rarely survived beyond the circumstances of its initial performance and was quickly forgotten along with its creator. In this regard Monteverdi fared better than most. His operatic works were revived in several cities in the decade following his death; according to Severo Bonini, writing in 1651, every musical household in Italy possessed a copy of the Lamento d'Arianna.
The German composer Heinrich Schütz, who had studied in Venice under Giovanni Gabrieli shortly before Monteverdi's arrival there, possessed a copy of Il combattimento and himself took up elements of the stile concitato. On his second visit to Venice in 1628–1629, Arnold believes, Schütz absorbed the concepts of basso continuo and expressiveness of word-setting, but he opines that Schütz was more directly influenced by the style of the younger generation of Venetian composers, including Grandi and Giovanni Rovetta (the eventual successor to Monteverdi at San Marco). Schütz published a first book of Symphoniae sacrae, settings of biblical texts in the style of seconda pratica, in Venice in 1629. Es steh Gott auf, from his Symphoniae sacrae II, published in Dresden in 1647, contains specific quotations from Monteverdi.
After the 1650s, Monteverdi's name quickly disappears from contemporary accounts, his music generally forgotten except for the Lamento, the prototype of a genre that would endure well into the 18th century.
Interest in Monteverdi revived in the late 18th and early 19th centuries among music scholars in Germany and Italy, although he was still regarded as essentially a historical curiosity. Wider interest in the music itself began in 1881, when Robert Eitner published a shortened version of the Orfeo score. Around this time Kurt Vogel scored the madrigals from the original manuscripts, but more critical interest was shown in the operas, following the discovery of the L'incoronazione manuscript in 1888 and that of Il ritorno in 1904. Largely through the efforts of Vincent d'Indy, all three operas were staged in one form or another, during the first quarter of the 20th century: L'Orfeo in May 1911, L'incoronazione in February 1913 and Il ritorno in May 1925.
The Italian nationalist poet Gabriele D'Annunzio lauded Monteverdi and in his novel Il fuoco (1900) wrote of "il divino Claudio ... what a heroic soul, purely Italian in its essence!" His vision of Monteverdi as the true founder of Italian musical lyricism was adopted by musicians who worked with the regime of Benito Mussolini (1922–1945), including Gian Francesco Malipiero, Luigi Dallapiccola, and Mario Labroca [it], who contrasted Monteverdi with the decadence of the music of Richard Strauss, Claude Debussy and Igor Stravinsky.
In the years after the Second World War the operas began to be performed in the major opera houses, and eventually were established in the general repertory. The resuscitation of Monteverdi's sacred music took longer; he did not benefit from the Catholic Church's 19th-century revival of Renaissance music in the way that Palestrina did, perhaps, as Carter suggests, because Monteverdi was viewed chiefly as a secular composer. It was not until 1932 that the 1610 Vespers were published in a modern edition, followed by Redlich's revision two years later. Modern editions of the Selva morale and Missa e Salmi volumes were published respectively in 1940 and 1942.
The revival of public interest in Monteverdi's music gathered pace in the second half of the 20th century, reaching full spate in the general early-music revival of the 1970s, during which time the emphasis turned increasingly towards "authentic" performance using historical instruments. The magazine Gramophone notes over 30 recordings of the Vespers between 1976 and 2011, and 27 of Il combattimento di Tancredi e Clorinda between 1971 and 2013. Monteverdi's surviving operas are today regularly performed; the website Operabase notes 555 performances of the operas in 149 productions worldwide in the seasons 2011–2016, ranking Monteverdi at 30th position for all composers, and at 8th ranking for Italian opera composers. In 1985, Manfred H. Stattkus published an index to Monteverdi's works, the Stattkus-Verzeichnis, (revised in 2006) giving each composition an "SV" number, to be used for cataloguing and references.
Monteverdi is lauded by modern critics as "the most significant composer in late Renaissance and early Baroque Italy"; "one of the principal composers in the history of Western music"; and, routinely, as the first great opera composer. These assessments reflect a contemporary perspective, since his music was largely unknown to the composers who followed him during an extensive period, spanning more than two centuries after his death. It is, as Redlich and others have pointed out, the composers of the 20th and 21st century who have rediscovered Monteverdi and sought to make his music a basis for their own. Possibly, as Chew suggests, they are attracted by Monteverdi's reputation as "a Modern, a breaker of rules, against the Ancients, those who deferred to ancient authority" – although the composer was, essentially, a pragmatist, "showing what can only be described as an opportunistic and eclectic willingness to use whatever lay to hand for the purpose". In a letter dated 16 October 1633, Monteverdi appears to endorse the view of himself as a "modern": "I would rather be moderately praised for the new style than greatly praised for the ordinary". However, Chew, in his final summation, sees the composer historically as facing both ways, willing to use modern techniques but while at the same time protective of his status as a competent composer in the stile antico. Thus, says Chew, "his achievement was both retrospective and progressive". Monteverdi represents the late Renaissance era while simultaneously summing up much of the early Baroque. "And in one respect in particular, his achievement was enduring: the effective projection of human emotions in music, in a way adequate for theatre as well as for chamber music." | [
{
"paragraph_id": 0,
"text": "Claudio Giovanni Antonio Monteverdi (baptized 15 May 1567 – 29 November 1643) was an Italian composer, choirmaster and string player. A composer of both secular and sacred music, and a pioneer in the development of opera, he is considered a crucial transitional figure between the Renaissance and Baroque periods of music history.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Born in Cremona, where he undertook his first musical studies and compositions, Monteverdi developed his career first at the court of Mantua (c. 1590–1613) and then until his death in the Republic of Venice where he was maestro di cappella at the basilica of San Marco. His surviving letters give insight into the life of a professional musician in Italy of the period, including problems of income, patronage and politics.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Much of Monteverdi's output, including many stage works, has been lost. His surviving music includes nine books of madrigals, large-scale religious works, such as his Vespro della Beata Vergine (Vespers for the Blessed Virgin) of 1610, and three complete operas. His opera L'Orfeo (1607) is the earliest of the genre still widely performed; towards the end of his life he wrote works for Venice, including Il ritorno d'Ulisse in patria and L'incoronazione di Poppea.",
"title": ""
},
{
"paragraph_id": 3,
"text": "While he worked extensively in the tradition of earlier Renaissance polyphony, as evidenced in his madrigals, he undertook great developments in form and melody, and began to employ the basso continuo technique, distinctive of the Baroque. No stranger to controversy, he defended his sometimes novel techniques as elements of a seconda pratica, contrasting with the more orthodox earlier style which he termed the prima pratica. Largely forgotten during the eighteenth and much of the nineteenth centuries, his works enjoyed a rediscovery around the beginning of the twentieth century. He is now established both as a significant influence in European musical history and as a composer whose works are regularly performed and recorded.",
"title": ""
},
{
"paragraph_id": 4,
"text": "Monteverdi was baptised in the church of SS Nazaro e Celso, Cremona, on 15 May 1567. The register records his name as \"Claudio Zuan Antonio\" the son of \"Messer Baldasar Mondeverdo\". He was the first child of the apothecary Baldassare Monteverdi and his first wife Maddalena (née Zignani); they had married early the previous year. Claudio's brother Giulio Cesare Monteverdi (b. 1573) was also to become a musician; there were two other brothers and two sisters from Baldassare's marriage to Maddalena and his subsequent marriage in 1576 or 1577. Cremona was close to the border of the Republic of Venice, and not far from the lands controlled by the Duchy of Mantua, in both of which states Monteverdi was later to establish his career.",
"title": "Life"
},
{
"paragraph_id": 5,
"text": "There is no clear record of Monteverdi's early musical training, or evidence that (as is sometimes claimed) he was a member of the Cathedral choir or studied at Cremona University. Monteverdi's first published work, a set of motets, Sacrae cantiunculae (Sacred Songs) for three voices, was issued in Venice in 1582, when he was only fifteen years old. In this, and his other initial publications, he describes himself as the pupil of Marc'Antonio Ingegneri, who was from 1581 (and possibly from 1576) to 1592 the maestro di cappella at Cremona Cathedral. The musicologist Tim Carter deduces that Ingegneri \"gave him a solid grounding in counterpoint and composition\", and that Monteverdi would also have studied playing instruments of the viol family and singing.",
"title": "Life"
},
{
"paragraph_id": 6,
"text": "Monteverdi's first publications also give evidence of his connections beyond Cremona, even in his early years. His second published work, Madrigali spirituali (Spiritual Madrigals, 1583), was printed at Brescia. His next works (his first published secular compositions) were sets of five-part madrigals, according to his biographer Paolo Fabbri: \"the inevitable proving ground for any composer of the second half of the sixteenth century ... the secular genre par excellence\". The first book of madrigals (Venice, 1587) was dedicated to Count Marco Verità of Verona; the second book of madrigals (Venice, 1590) was dedicated to the President of the Senate of Milan, Giacomo Ricardi, for whom he had played the viola da braccio in 1587.",
"title": "Life"
},
{
"paragraph_id": 7,
"text": "In the dedication of his second book of madrigals, Monteverdi had described himself as a player of the vivuola (which could mean either viola da gamba or viola da braccio). In 1590 or 1591 he entered the service of Duke Vincenzo I Gonzaga of Mantua; he recalled in his dedication to the Duke of his third book of madrigals (Venice, 1592) that \"the most noble exercise of the vivuola opened to me the fortunate way into your service.\" In the same dedication he compares his instrumental playing to \"flowers\" and his compositions as \"fruit\" which as it matures \"can more worthily and more perfectly serve you\", indicating his intentions to establish himself as a composer.",
"title": "Life"
},
{
"paragraph_id": 8,
"text": "Duke Vincenzo was keen to establish his court as a musical centre, and sought to recruit leading musicians. When Monteverdi arrived in Mantua, the maestro di capella at the court was the Flemish musician Giaches de Wert. Other notable musicians at the court during this period included the composer and violinist Salomone Rossi, Rossi's sister, the singer Madama Europa, and Francesco Rasi. Monteverdi married the court singer Claudia de Cattaneis in 1599; they were to have three children, two sons (Francesco, b. 1601 and Massimiliano, b. 1604), and a daughter who died soon after birth in 1603. Monteverdi's brother Giulio Cesare joined the court musicians in 1602.",
"title": "Life"
},
{
"paragraph_id": 9,
"text": "When Wert died in 1596, his post was given to Benedetto Pallavicino, but Monteverdi was clearly highly regarded by Vincenzo and accompanied him on his military campaigns in Hungary (1595) and also on a visit to Flanders in 1599. Here at the town of Spa he is reported by his brother Giulio Cesare as encountering, and bringing back to Italy, the canto alla francese. (The meaning of this, literally \"song in the French style\", is debatable, but may refer to the French-influenced poetry of Gabriello Chiabrera, some of which was set by Monteverdi in his Scherzi musicali, and which departs from the traditional Italian style of lines of 9 or 11 syllables). Monteverdi may possibly have been a member of Vincenzo's entourage at Florence in 1600 for the marriage of Maria de' Medici and Henry IV of France, at which celebrations Jacopo Peri's opera Euridice (the earliest surviving opera) was premiered. On the death of Pallavicino in 1601, Monteverdi was confirmed as the new maestro di capella.",
"title": "Life"
},
{
"paragraph_id": 10,
"text": "At the turn of the 17th century, Monteverdi found himself the target of musical controversy. The influential Bolognese theorist Giovanni Maria Artusi attacked Monteverdi's music (without naming the composer) in his work L'Artusi, overo Delle imperfettioni della moderna musica (Artusi, or On the imperfections of modern music) of 1600, followed by a sequel in 1603. Artusi cited extracts from Monteverdi's works not yet published (they later formed parts of his fourth and fifth books of madrigals of 1603 and 1605), condemning their use of harmony and their innovations in use of musical modes, compared to orthodox polyphonic practice of the sixteenth century. Artusi attempted to correspond with Monteverdi on these issues; the composer refused to respond, but found a champion in a pseudonymous supporter, \"L'Ottuso Academico\" (\"The Obtuse Academic\"). Eventually Monteverdi replied in the preface to the fifth book of madrigals that his duties at court prevented him from a detailed reply; but in a note to \"the studious reader\", he claimed that he would shortly publish a response, Seconda Pratica, overo Perfettione della Moderna Musica (The Second Style, or Perfection of Modern Music). This work never appeared, but a later publication by Claudio's brother Giulio Cesare made it clear that the seconda pratica which Monteverdi defended was not seen by him as a radical change or his own invention, but was an evolution from previous styles (prima pratica) which was complementary to them.",
"title": "Life"
},
{
"paragraph_id": 11,
"text": "This debate seems in any case to have raised the composer's profile, leading to reprints of his earlier books of madrigals. Some of his madrigals were published in Copenhagen in 1605 and 1606, and the poet Tommaso Stigliani (1573–1651) published a eulogy of him in his 1605 poem \"O sirene de' fiumi\". The composer of madrigal comedies and theorist Adriano Banchieri wrote in 1609: \"I must not neglect to mention the most noble of composers, Monteverdi ... his expressive qualities are truly deserving of the highest commendation, and we find in them countless examples of matchless declamation ... enhanced by comparable harmonies.\" The modern music historian Massimo Ossi has placed the Artusi issue in the context of Monteverdi's artistic development: \"If the controversy seems to define Monteverdi's historical position, it also seems to have been about stylistic developments that by 1600 Monteverdi had already outgrown\".",
"title": "Life"
},
{
"paragraph_id": 12,
"text": "The non-appearance of Monteverdi's promised explanatory treatise may have been a deliberate ploy, since by 1608, by Monteverdi's reckoning, Artusi had become fully reconciled to modern trends in music, and the seconda pratica was by then well established; Monteverdi had no need to revisit the issue. On the other hand, letters to Giovanni Battista Doni of 1632 show that Monteverdi was still preparing a defence of the seconda practica, in a treatise entitled Melodia; he may still have been working on this at the time of his death ten years later.",
"title": "Life"
},
{
"paragraph_id": 13,
"text": "In 1606 Vincenzo's heir Francesco commissioned from Monteverdi the opera L'Orfeo, to a libretto by Alessandro Striggio, for the Carnival season of 1607. It was given two performances in February and March 1607; the singers included, in the title role, Rasi, who had sung in the first performance of Euridice witnessed by Vincenzo in 1600. This was followed in 1608 by the opera L'Arianna (libretto by Ottavio Rinuccini), intended for the celebration of the marriage of Francesco to Margherita of Savoy. All the music for this opera is lost apart from Ariadne's Lament, which became extremely popular. To this period also belongs the ballet entertainment Il ballo delle ingrate.",
"title": "Life"
},
{
"paragraph_id": 14,
"text": "The strain of the hard work Monteverdi had been putting into these and other compositions was exacerbated by personal tragedies. His wife died in September 1607 and the young singer Caterina Martinelli, intended for the title role of Arianna, died of smallpox in March 1608. Monteverdi also resented his increasingly poor financial treatment by the Gonzagas. He retired to Cremona in 1608 to convalesce, and wrote a bitter letter to Vincenzo's minister Annibale Chieppio in November of that year seeking (unsuccessfully) \"an honourable dismissal\". Although the Duke increased Monteverdi's salary and pension, and Monteverdi returned to continue his work at the court, he began to seek patronage elsewhere. After publishing his Vespers in 1610, which were dedicated to Pope Paul V, he visited Rome, ostensibly hoping to place his son Francesco at a seminary, but apparently also seeking alternative employment. In the same year he may also have visited Venice, where a large collection of his church music was being printed, with a similar intention.",
"title": "Life"
},
{
"paragraph_id": 15,
"text": "Duke Vincenzo died on 18 February 1612. When Francesco succeeded him, court intrigues and cost-cutting led to the dismissal of Monteverdi and his brother Giulio Cesare, who both returned, almost penniless, to Cremona. Despite Francesco's own death from smallpox in December 1612, Monteverdi was unable to return to favour with his successor, his brother Cardinal Ferdinando Gonzaga. In 1613, following the death of Giulio Cesare Martinengo, Monteverdi auditioned for his post as maestro at the basilica of San Marco in Venice, for which he submitted music for a Mass. He was appointed in August 1613, and given 50 ducats for his expenses (of which he was robbed, together with his other belongings, by highwaymen at Sanguinetto on his return to Cremona).",
"title": "Life"
},
{
"paragraph_id": 16,
"text": "Martinengo had been ill for some time before his death and had left the music of San Marco in a fragile state. The choir had been neglected and the administration overlooked. When Monteverdi arrived to take up his post, his principal responsibility was to recruit, train, discipline and manage the musicians of San Marco (the capella), who amounted to about 30 singers and six instrumentalists; the numbers could be increased for major events. Among the recruits to the choir was Francesco Cavalli, who joined in 1616 at the age of 14; he was to remain connected with San Marco throughout his life, and was to develop a close association with Monteverdi. Monteverdi also sought to expand the repertory, including not only the traditional a cappella repertoire of Roman and Flemish composers, but also examples of the modern style which he favoured, including the use of continuo and other instruments. Apart from this he was of course expected to compose music for all the major feasts of the church. This included a new mass each year for Holy Cross Day and Christmas Eve, cantatas in honour of the Venetian Doge, and numerous other works (many of which are lost). Monteverdi was also free to obtain income by providing music for other Venetian churches and for other patrons, and was frequently commissioned to provide music for state banquets. The Procurators of San Marco, to whom Monteverdi was directly responsible, showed their satisfaction with his work in 1616 by raising his annual salary from 300 ducats to 400.",
"title": "Life"
},
{
"paragraph_id": 17,
"text": "The relative freedom which the Republic of Venice afforded him, compared to the problems of court politics in Mantua, are reflected in Monteverdi's letters to Striggio, particularly his letter of 13 March 1620, when he rejects an invitation to return to Mantua, extolling his present position and finances in Venice, and referring to the pension which Mantua still owes him. Nonetheless, remaining a Mantuan citizen, he accepted commissions from the new Duke Ferdinando, who had formally renounced his position as Cardinal in 1616 to take on the duties of state. These included the balli Tirsi e Clori (1616) and Apollo (1620), an opera Andromeda (1620) and an intermedio, Le nozze di Tetide, for the marriage of Ferdinando with Caterina de' Medici (1617). Most of these compositions were extensively delayed in creation – partly, as shown by surviving correspondence, through the composer's unwillingness to prioritise them, and partly because of constant changes in the court's requirements. They are now lost, apart from Tirsi e Clori, which was included in the seventh book of madrigals (published 1619) and dedicated to the Duchess Caterina, for which the composer received a pearl necklace from the Duchess. A subsequent major commission, the opera La finta pazza Licori, to a libretto by Giulio Strozzi, was completed for Fernando's successor Vincenzo II, who succeeded to the dukedom in 1626. Because of the latter's illness (he died in 1627), it was never performed, and it is now also lost.",
"title": "Life"
},
{
"paragraph_id": 18,
"text": "Monteverdi also received commissions from other Italian states and from their communities in Venice. These included, for the Milanese community in 1620, music for the Feast of St. Charles Borromeo, and for the Florentine community a Requiem Mass for Cosimo II de' Medici (1621). Monteverdi acted on behalf of Paolo Giordano II, Duke of Bracciano, to arrange publication of works by the Cremona musician Francesco Petratti. Among Monteverdi's private Venetian patrons was the nobleman Girolamo Mocenigo, at whose home was premiered in 1624 the dramatic entertainment Il combattimento di Tancredi e Clorinda based on an episode from Torquato Tasso's La Gerusalemme liberata. In 1627 Monteverdi received a major commission from Odoardo Farnese, Duke of Parma, for a series of works, and gained leave from the Procurators to spend time there during 1627 and 1628.",
"title": "Life"
},
{
"paragraph_id": 19,
"text": "Monteverdi's musical direction received the attention of foreign visitors. The Dutch diplomat and musician Constantijn Huygens, attending a Vespers service at the church of SS. Giovanni e Lucia, wrote that he \"heard the most perfect music I had ever heard in my life. It was directed by the most famous Claudio Monteverdi ... who was also the composer and was accompanied by four theorbos, two cornettos, two bassoons, one basso de viola of huge size, organs and other instruments ...\". Monteverdi wrote a mass, and provided other musical entertainment, for the visit to Venice in 1625 of the Crown Prince Władysław of Poland, who may have sought to revive attempts made a few years previously to lure Monteverdi to Warsaw. He also provided chamber music for Wolfgang Wilhelm, Count Palatine of Neuburg, when the latter was paying an incognito visit to Venice in July 1625.",
"title": "Life"
},
{
"paragraph_id": 20,
"text": "Correspondence of Monteverdi in 1625 and 1626 with the Mantuan courtier Ercole Marigliani reveals an interest in alchemy, which apparently Monteverdi had taken up as a hobby. He discusses experiments to transform lead into gold, the problems of obtaining mercury, and mentions commissioning special vessels for his experiments from the glassworks at Murano.",
"title": "Life"
},
{
"paragraph_id": 21,
"text": "Despite his generally satisfactory situation in Venice, Monteverdi experienced personal problems from time to time. He was on one occasion – probably because of his wide network of contacts – the subject of an anonymous denunciation to the Venetian authorities alleging that he supported the Habsburgs. He was also subject to anxieties about his children. His son Francesco, while a student of law at Padua in 1619, was spending in Monteverdi's opinion too much time with music, and he, therefore, moved him to the University of Bologna. This did not have the required result, and it seems that Monteverdi resigned himself to Francesco having a musical career – he joined the choir of San Marco in 1623. His other son Massimiliano, who graduated in medicine, was arrested by the Inquisition in Mantua in 1627 for reading forbidden literature. Monteverdi was obliged to sell the necklace he had received from Duchess Caterina to pay for his son's (eventually successful) defence. Monteverdi wrote at the time to Striggio seeking his help, and fearing that Massimiliano might be subject to torture; it seems that Striggio's intervention was helpful. Money worries at this time also led Monteverdi to visit Cremona to secure for himself a church canonry.",
"title": "Life"
},
{
"paragraph_id": 22,
"text": "A series of disturbing events troubled Monteverdi's world in the period around 1630. Mantua was invaded by Habsburg armies in 1630, who besieged the plague-stricken town, and after its fall in July looted its treasures, and dispersed the artistic community. The plague was carried to Mantua's ally Venice by an embassy led by Monteverdi's confidante Striggio, and over a period of 16 months led to over 45,000 deaths, leaving Venice's population in 1633 at just above 100,000, the lowest level for about 150 years. Among the plague victims was Monteverdi's assistant at San Marco, and a notable composer in his own right, Alessandro Grandi. The plague and the after-effects of war had an inevitable deleterious effect on the economy and artistic life of Venice. Monteverdi's younger brother Giulio Cesare also died at this time, probably from the plague.",
"title": "Life"
},
{
"paragraph_id": 23,
"text": "By this time Monteverdi was in his sixties, and his rate of composition seems to have slowed down. He had written a setting of Strozzi's Proserpina rapita (The Abduction of Proserpina), now lost except for one vocal trio, for a Mocenigo wedding in 1630, and produced a Mass for deliverance from the plague for San Marco which was performed in November 1631. His set of Scherzi musicali was published in Venice in 1632. In 1631, Monteverdi was admitted to the tonsure, and was ordained deacon, and later priest, in 1632. Although these ceremonies took place in Venice, he was nominated as a member of Diocese of Cremona; this may imply that he intended to retire there.",
"title": "Life"
},
{
"paragraph_id": 24,
"text": "The opening of the opera house of San Cassiano in 1637, the first public opera house in Europe, stimulated the city's musical life and coincided with a new burst of the composer's activity. The year 1638 saw the publication of Monteverdi's eighth book of madrigals and a revision of the Ballo delle ingrate. The eighth book contains a ballo, \"Volgendi il ciel\", which may have been composed for the Holy Roman Emperor, Ferdinand III, to whom the book is dedicated. The years 1640–1641 saw the publication of the extensive collection of church music, Selva morale e spirituale. Among other commissions, Monteverdi wrote music in 1637 and 1638 for Strozzi's \"Accademia degli Unisoni\" in Venice, and in 1641 a ballet, La vittoria d'Amore, for the court of Piacenza.",
"title": "Life"
},
{
"paragraph_id": 25,
"text": "Monteverdi was still not entirely free from his responsibilities for the musicians at San Marco. He wrote to complain about one of his singers to the Procurators, on 9 June 1637: \"I, Claudio Monteverdi ... come humbly ... to set forth to you how Domenicato Aldegati ... a bass, yesterday morning ... at the time of the greatest concourse of people ... spoke these exact words ...'The Director of Music comes from a brood of cut-throat bastards, a thieving, fucking, he-goat ... and I shit on him and whoever protects him ...'\".",
"title": "Life"
},
{
"paragraph_id": 26,
"text": "Monteverdi's contribution to opera at this period is notable. He revised his earlier opera L'Arianna in 1640 and wrote three new works for the commercial stage, Il ritorno d'Ulisse in patria (The Return of Ulysses to his Homeland, 1640, first performed in Bologna with Venetian singers), Le nozze d'Enea e Lavinia (The Marriage of Aeneas and Lavinia, 1641, music now lost), and L'incoronazione di Poppea (The Coronation of Poppea, 1643). The introduction to the printed scenario of Le nozze d'Enea, by an unknown author, acknowledges that Monteverdi is to be credited for the rebirth of theatrical music and that \"he will be sighed for in later ages, for his compositions will surely outlive the ravages of time.\"",
"title": "Life"
},
{
"paragraph_id": 27,
"text": "In his last surviving letter (20 August 1643), Monteverdi, already ill, was still hoping for the settlement of the long-disputed pension from Mantua, and asked the Doge of Venice to intervene on his behalf. He died in Venice on 29 November 1643, after paying a brief visit to Cremona, and is buried in the Church of the Frari. He was survived by his sons; Masimilliano died in 1661, Francesco after 1677.",
"title": "Life"
},
{
"paragraph_id": 28,
"text": "There is a consensus among music historians that a period extending from the mid-15th century to around 1625, characterised in Lewis Lockwood's phrase by \"substantial unity of outlook and language\", should be identified as the period of \"Renaissance music\". Musical literature has also defined the succeeding period (covering music from approximately 1580 to 1750) as the era of \"Baroque music\". It is in the late-16th to early-17th-century overlap of these periods that much of Monteverdi's creativity flourished; he stands as a transitional figure between the Renaissance and the Baroque.",
"title": "Music"
},
{
"paragraph_id": 29,
"text": "In the Renaissance era, music had developed as a formal discipline, a \"pure science of relationships\" in the words of Lockwood. In the Baroque era it became a form of aesthetic expression, increasingly used to adorn religious, social and festive celebrations in which, in accordance with Plato's ideal, the music was subordinated to the text. Solo singing with instrumental accompaniment, or monody, acquired greater significance towards the end of the 16th century, replacing polyphony as the principal means of dramatic music expression. This was the changing world in which Monteverdi was active. Percy Scholes in his Oxford Companion to Music describes the \"new music\" thus: \"[Composers] discarded the choral polyphony of the madrigal style as barbaric, and set dialogue or soliloquy for single voices, imitating more or less the inflexions of speech and accompanying the voice by playing mere supporting chords. Short choruses were interspersed, but they too were homophonic rather than polyphonic.\"",
"title": "Music"
},
{
"paragraph_id": 30,
"text": "Ingegneri, Monteverdi's first tutor, was a master of the musica reservata vocal style, which involved the use of chromatic progressions and word-painting; Monteverdi's early compositions were grounded in this style. Ingegneri was a traditional Renaissance composer, \"something of an anachronism\", according to Arnold, but Monteverdi also studied the work of more \"modern\" composers such as Luca Marenzio, Luzzasco Luzzaschi, and a little later, Giaches de Wert, from whom he would learn the art of expressing passion. He was a precocious and productive student, as indicated by his youthful publications of 1582–83. Mark Ringer writes that \"these teenaged efforts reveal palpable ambition matched with a convincing mastery of contemporary style\", but at this stage they display their creator's competence rather than any striking originality. Geoffrey Chew classifies them as \"not in the most modern vein for the period\", acceptable but out-of-date. Chew rates the Canzonette collection of 1584 much more highly than the earlier juvenilia: \"These brief three-voice pieces draw on the airy, modern style of the villanellas of Marenzio, [drawing on] a substantial vocabulary of text-related madrigalisms\".",
"title": "Music"
},
{
"paragraph_id": 31,
"text": "The canzonetta form was much used by composers of the day as a technical exercise, and is a prominent element in Monteverdi's first book of madrigals published in 1587. In this book, the playful, pastoral settings again reflect the style of Marenzio, while Luzzaschi's influence is evident in Monteverdi's use of dissonance. The second book (1590) begins with a setting modelled on Marenzio of a modern verse, Torquato Tasso's \"Non si levav' ancor\", and concludes with a text from 50 years earlier: Pietro Bembo's \"Cantai un tempo\". Monteverdi set the latter to music in an archaic style reminiscent of the long-dead Cipriano de Rore. Between them is \"Ecco mormorar l'onde\", strongly influenced by de Wert and hailed by Chew as the great masterpiece of the second book.",
"title": "Music"
},
{
"paragraph_id": 32,
"text": "A thread common throughout these early works is Monteverdi's use of the technique of imitatio, a general practice among composers of the period whereby material from earlier or contemporary composers was used as models for their own work. Monteverdi continued to use this procedure well beyond his apprentice years, a factor that in some critics' eyes has compromised his reputation for originality.",
"title": "Music"
},
{
"paragraph_id": 33,
"text": "Monteverdi's first fifteen years of service in Mantua are bracketed by his publications of the third book of madrigals in 1592 and the fourth and fifth books in 1603 and 1605. Between 1592 and 1603 he made minor contributions to other anthologies. How much he composed in this period is a matter of conjecture; his many duties in the Mantuan court may have limited his opportunities, but several of the madrigals that he published in the fourth and fifth books were written and performed during the 1590s, some figuring prominently in the Artusi controversy.",
"title": "Music"
},
{
"paragraph_id": 34,
"text": "The third book shows strongly the increased influence of Wert, by that time Monteverdi's direct superior as maestro de capella at Mantua. Two poets dominate the collection: Tasso, whose lyrical poetry had figured prominently in the second book but is here represented through the more epic, heroic verses from Gerusalemme liberata, and Giovanni Battista Guarini, whose verses had appeared sporadically in Monteverdi's earlier publications, but form around half of the contents of the third book. Wert's influence is reflected in Monteverdi's forthrightly modern approach, and his expressive and chromatic settings of Tasso's verses. Of the Guarini settings, Chew writes: \"The epigrammatic style ... closely matches a poetic and musical ideal of the period ... [and] often depends on strong, final cadential progressions, with or without the intensification provided by chains of suspended dissonances\". Chew cites the setting of \"Stracciami pur il core\" as \"a prime example of Monteverdi's irregular dissonance practice\". Tasso and Guarini were both regular visitors to the Mantuan court; Monteverdi's association with them and his absorption of their ideas may have helped lay the foundations of his own approach to the musical dramas that he would create a decade later.",
"title": "Music"
},
{
"paragraph_id": 35,
"text": "As the 1590s progressed, Monteverdi moved closer towards the form that he would identify in due course as the seconda pratica. Claude V. Palisca quotes the madrigal Ohimè, se tanto amate, published in the fourth book but written before 1600 – it is among the works attacked by Artusi – as a typical example of the composer's developing powers of invention. In this madrigal Monteverdi again departs from the established practice in the use of dissonance, by means of a vocal ornament Palisca describes as échappé. Monteverdi's daring use of this device is, says Palisca, \"like a forbidden pleasure\". In this and in other settings the poet's images were supreme, even at the expense of musical consistency.",
"title": "Music"
},
{
"paragraph_id": 36,
"text": "The fourth book includes madrigals to which Artusi objected on the grounds of their \"modernism\". However, Ossi describes it as \"an anthology of disparate works firmly rooted in the 16th century\", closer in nature to the third book than to the fifth. Besides Tasso and Guarini, Monteverdi set to music verses by Rinuccini, Maurizio Moro (Sì ch'io vorrei morire) and Ridolfo Arlotti (Luci serene e chiare). There is evidence of the composer's familiarity with the works of Carlo Gesualdo, and with composers of the school of Ferrara such as Luzzaschi; the book was dedicated to a Ferrarese musical society, the Accademici Intrepidi.",
"title": "Music"
},
{
"paragraph_id": 37,
"text": "The fifth book looks more to the future; for example, Monteverdi employs the concertato style with basso continuo (a device that was to become a typical feature in the emergent Baroque era), and includes a sinfonia (instrumental interlude) in the final piece. He presents his music through complex counterpoint and daring harmonies, although at times combining the expressive possibilities of the new music with traditional polyphony.",
"title": "Music"
},
{
"paragraph_id": 38,
"text": "Aquilino Coppini drew much of the music for his sacred contrafacta of 1608 from Monteverdi's 3rd, 4th and 5th books of madrigals. In writing to a friend in 1609 Coppini commented that Monteverdi's pieces \"require, during their performance, more flexible rests and bars that are not strictly regular, now pressing forward or abandoning themselves to slowing down [...] In them there is a truly wondrous capacity for moving the affections\".",
"title": "Music"
},
{
"paragraph_id": 39,
"text": "In Monteverdi's final five years' service in Mantua he completed the operas L'Orfeo (1607) and L'Arianna (1608), and wrote quantities of sacred music, including the Messa in illo tempore (1610) and also the collection known as Vespro della Beata Vergine which is often referred to as \"Monteverdi's Vespers\" (1610). He also published Scherzi musicale a tre voci (1607), settings of verses composed since 1599 and dedicated to the Gonzaga heir, Francesco. The vocal trio in the Scherzi comprises two sopranos and a bass, accompanied by simple instrumental ritornellos. According to Bowers the music \"reflected the modesty of the prince's resources; it was, nevertheless, the earliest publication to associate voices and instruments in this particular way\".",
"title": "Music"
},
{
"paragraph_id": 40,
"text": "The opera opens with a brief trumpet toccata. The prologue of La musica (a figure representing music) is introduced with a ritornello by the strings, repeated often to represent the \"power of music\" – one of the earliest examples of an operatic leitmotif. Act 1 presents a pastoral idyll, the buoyant mood of which continues into Act 2. The confusion and grief which follow the news of Euridice's death are musically reflected by harsh dissonances and the juxtaposition of keys. The music remains in this vein until the act ends with the consoling sounds of the ritornello.",
"title": "Music"
},
{
"paragraph_id": 41,
"text": "Act 3 is dominated by Orfeo's aria \"Possente spirto e formidabil nume\" by which he attempts to persuade Caronte to allow him to enter Hades. Monteverdi's vocal embellishments and virtuoso accompaniment provide what Tim Carter has described as \"one of the most compelling visual and aural representations\" in early opera. In Act 4 the warmth of Proserpina's singing on behalf of Orfeo is retained until Orfeo fatally \"looks back\". The brief final act, which sees Orfeo's rescue and metamorphosis, is framed by the final appearance of the ritornello and by a lively moresca that brings the audience back to their everyday world.",
"title": "Music"
},
{
"paragraph_id": 42,
"text": "Throughout the opera Monteverdi makes innovative use of polyphony, extending the rules beyond the conventions which composers normally observed in fidelity to Palestrina. He combines elements of the traditional 16th-century madrigal with the new monodic style where the text dominates the music and sinfonias and instrumental ritornellos illustrate the action.",
"title": "Music"
},
{
"paragraph_id": 43,
"text": "The music for this opera is lost except for the Lamento d'Arianna, which was published in the sixth book in 1614 as a five-voice madrigal; a separate monodic version was published in 1623. In its operatic context the lament depicts Arianna's various emotional reactions to her abandonment: sorrow, anger, fear, self-pity, desolation and a sense of futility. Throughout, indignation and anger are punctuated by tenderness, until a descending line brings the piece to a quiet conclusion.",
"title": "Music"
},
{
"paragraph_id": 44,
"text": "The musicologist Suzanne Cusick writes that Monteverdi \"creat[ed] the lament as a recognizable genre of vocal chamber music and as a standard scene in opera ... that would become crucial, almost genre-defining, to the full-scale public operas of 17th-century Venice\". Cusick observes how Monteverdi is able to match in music the \"rhetorical and syntactical gestures\" in the text of Ottavio Rinuccini. The opening repeated words \"Lasciatemi morire\" (Let me die) are accompanied by a dominant seventh chord which Ringer describes as \"an unforgettable chromatic stab of pain\". Ringer suggests that the lament defines Monteverdi's innovative creativity in a manner similar to that in which the Prelude and the Liebestod in Tristan und Isolde announced Wagner's discovery of new expressive frontiers.",
"title": "Music"
},
{
"paragraph_id": 45,
"text": "Rinuccini's full libretto, which has survived, was set in modern times by Alexander Goehr (Arianna, 1995), including a version of Monteverdi's Lament.",
"title": "Music"
},
{
"paragraph_id": 46,
"text": "The Vespro della Beata Vergine, Monteverdi's first published sacred music since the Madrigali spirituali of 1583, consists of 14 components: an introductory versicle and response, five psalms interspersed with five \"sacred concertos\" (Monteverdi's term), a hymn, and two Magnificat settings. Collectively these pieces fulfil the requirements for a Vespers service on any feast day of the Virgin. Monteverdi employs many musical styles; the more traditional features, such as cantus firmus, falsobordone and Venetian canzone, are mixed with the latest madrigal style, including echo effects and chains of dissonances. Some of the musical features used are reminiscent of L'Orfeo, written slightly earlier for similar instrumental and vocal forces.",
"title": "Music"
},
{
"paragraph_id": 47,
"text": "In this work the \"sacred concertos\" fulfil the role of the antiphons which divide the psalms in regular Vespers services. Their non-liturgical character has led writers to question whether they should be within the service, or indeed whether this was Monteverdi's intention. In some versions of Monteverdi's Vespers (for example, those of Denis Stevens) the concertos are replaced with antiphons associated with the Virgin, although John Whenham in his analysis of the work argues that the collection as a whole should be regarded as a single liturgical and artistic entity.",
"title": "Music"
},
{
"paragraph_id": 48,
"text": "All the psalms, and the Magnificat, are based on melodically limited and repetitious Gregorian chant psalm tones, around which Monteverdi builds a range of innovative textures. This concertato style challenges the traditional cantus firmus, and is most evident in the \"Sonata sopra Sancta Maria\", written for eight string and wind instruments plus basso continuo, and a single soprano voice. Monteverdi uses modern rhythms, frequent metre changes and constantly varying textures; yet, according to John Eliot Gardiner, \"for all the virtuosity of its instrumental writing and the evident care which has gone into the combinations of timbre\", Monteverdi's chief concern was resolving the proper combination of words and music.",
"title": "Music"
},
{
"paragraph_id": 49,
"text": "The actual musical ingredients of the Vespers were not novel to Mantua – concertato had been used by Lodovico Grossi da Viadana, a former choirmaster at the cathedral of Mantua, while the Sonata sopra had been anticipated by Archangelo Crotti in his Sancta Maria published in 1608. It is, writes Denis Arnold, Monteverdi's mixture of the various elements that makes the music unique. Arnold adds that the Vespers achieved fame and popularity only after their 20th-century rediscovery; they were not particularly regarded in Monteverdi's time.",
"title": "Music"
},
{
"paragraph_id": 50,
"text": "During his years in Venice Monteverdi published his sixth (1614), seventh (1619) and eighth (1638) books of madrigals. The sixth book consists of works written before the composer's departure from Mantua. Hans Redlich sees it as a transitional work, containing Monteverdi's last madrigal compositions in the manner of the prima pratica, together with music which is typical of the new style of expression which Monteverdi had displayed in the dramatic works of 1607–08. The central theme of the collection is loss; the best-known work is the five-voice version of the Lamento d'Arianna, which, says Massimo Ossi, gives \"an object lesson in the close relationship between monodic recitative and counterpoint\". The book contains Monteverdi's first settings of verses by Giambattista Marino, and two settings of Petrarch which Ossi considers the most extraordinary pieces in the volume, providing some \"stunning musical moments\".",
"title": "Music"
},
{
"paragraph_id": 51,
"text": "While Monteverdi had looked backwards in the sixth book, he moved forward in the seventh book from the traditional concept of the madrigal, and from monody, in favour of chamber duets. There are exceptions, such the two solo lettere amorose (love letters) \"Se i languidi miei sguardi\" and \"Se pur destina e vole\", written to be performed genere rapresentativo – acted as well as sung. Of the duets which are the main features of the volume, Chew highlights \"Ohimé, dov'è il mio ben, dov'è il mio core\", a romanesca in which two high voices express dissonances above a repetitive bass pattern. The book also contains large-scale ensemble works, and the ballet Tirsi e Clori. This was the height of Monteverdi's \"Marino period\"; six of the pieces in the book are settings of the poet's verses. As Carter puts it, Monteverdi \"embraced Marino's madrigalian kisses and love-bites with ... the enthusiasm typical of the period\". Some commentators have opined that the composer should have had better poetic taste.",
"title": "Music"
},
{
"paragraph_id": 52,
"text": "The eighth book, subtitled Madrigali guerrieri, et amorosi ... (\"Madrigals of war and love\") is structured in two symmetrical halves, one for \"war\" and one for \"love\". Each half begins with a six-voice setting, followed by an equally large-scale Petrarch setting, then a series of duets mainly for tenor voices, and concludes with a theatrical number and a final ballet. The \"war\" half contains several items written as tributes to the emperor Ferdinand III, who had succeeded to the Habsburg throne in 1637. Many of Monteverdi's familiar poets – Strozzi, Rinuccini, Tasso, Marino, Guarini – are represented in the settings.",
"title": "Music"
},
{
"paragraph_id": 53,
"text": "It is difficult to gauge when many of the pieces were composed, although the ballet Mascherata dell' ingrate that ends the book dates back to 1608 and the celebration of the Gonzaga-Savoy marriage. The Combattimento di Tancredi e Clorinda, centrepiece of the \"war\" settings, had been written and performed in Venice in 1624; on its publication in the eighth book, Monteverdi explicitly linked it to his concept of concitato genera (otherwise stile concitato – \"aroused style\") that would \"fittingly imitate the utterance and the accents of a brave man who is engaged in warfare\", and implied that since he had originated this style, others had begun to copy it. The work employed for the first time instructions for the use of pizzicato string chords, and also evocations of fanfares and other sounds of combat.",
"title": "Music"
},
{
"paragraph_id": 54,
"text": "The critic Andrew Clements describes the eighth book as \"a statement of artistic principles and compositional authority\", in which Monteverdi \"shaped and expanded the madrigal form to accommodate what he wanted to do ... the pieces collected in Book Eight make up a treasury of what music in the first half the 17th century could possibly express.\"",
"title": "Music"
},
{
"paragraph_id": 55,
"text": "During this period of his Venetian residency, Monteverdi composed quantities of sacred music. Numerous motets and other short works were included in anthologies by local publishers such as Giulio Cesare Bianchi (a former student of Monteverdi) and Lorenzo Calvi, and others were published elsewhere in Italy and Austria. The range of styles in the motets is broad, from simple strophic arias with string accompaniment to full-scale declamations with an alleluia finale.",
"title": "Music"
},
{
"paragraph_id": 56,
"text": "Monteverdi retained emotional and political attachments to the Mantuan court and wrote for it, or undertook to write, large amounts of stage music including at least four operas. The ballet Tirsi e Clori survives through its inclusion in the seventh book, but the rest of the Mantuan dramatic music is lost. Many of the missing manuscripts may have disappeared in the wars that overcame Mantua in 1630. The most significant aspect of their loss, according to Carter, is the extent to which they might have provided musical links between Monteverdi's early Mantuan operas and those he wrote in Venice after 1638: \"Without these links ... it is hard to a produce a coherent account of his development as a composer for the stage\". Likewise, Janet Beat regrets that the 30-year gap hampers the study of how opera orchestration developed during those critical early years.",
"title": "Music"
},
{
"paragraph_id": 57,
"text": "Apart from the madrigal books, Monteverdi's only published collection during this period was the volume of Scherzi musicale in 1632. For unknown reasons, the composer's name does not appear on the inscription, the dedication being signed by the Venetian printer Bartolomeo Magni; Carter surmises that the recently ordained Monteverdi may have wished to keep his distance from this secular collection. It mixes strophic continuo songs for solo voice with more complex works which employ continuous variation over repeated bass patterns. Chew selects the chaconne for two tenors, Zefiro torna e di soavi accenti, as the outstanding item in the collection: \"[T]he greater part of this piece consists of repetitions of a bass pattern which ensures tonal unity of a simple kind, owing to its being framed as a simple cadence in a G major tonal type: over these repetitions, inventive variations unfold in virtuoso passage-work\".",
"title": "Music"
},
{
"paragraph_id": 58,
"text": "Main articles: Il ritorno d'Ulisse in patria; L'incoronazione di Poppea; Selva morale e spirituale",
"title": "Music"
},
{
"paragraph_id": 59,
"text": "The last years of Monteverdi's life were much occupied with opera for the Venetian stage. Richard Taruskin, in his Oxford History of Western Music, gave his chapter on this topic the title \"Opera from Monteverdi to Monteverdi.\" This wording, originally proposed humorously by the Italian music historian Nino Pirrotta, is interpreted seriously by Taruskin as indicating that Monteverdi is significantly responsible for the transformation of the opera genre from a private entertainment of the nobility (as with Orfeo in 1607), to what became a major commercial genre, as exemplified by his opera L'incoronazione di Poppea (1643). His two surviving operatic works of this period, Il ritorno d'Ulisse in patria and L'incoronazione are held by Arnold to be the first \"modern\" operas; Il ritorno is the first Venetian opera to depart from what Ellen Rosand terms \"the mythological pastoral\". However, David Johnson in the North American Review warns audiences not to expect immediate affinity with Mozart, Verdi or Puccini: \"You have to submit yourself to a much slower pace, to a much more chaste conception of melody, to a vocal style that is at first merely like dry declamation and only on repeated hearings begins to assume an extraordinary eloquence.\"",
"title": "Music"
},
{
"paragraph_id": 60,
"text": "Il ritorno, says Carter, is clearly influenced by Monteverdi's earlier works. Penelope's lament in Act I is close in character to the lament from L'Arianna, while the martial episodes recall Il combattimento. Stile concitato is prominent in the fight scenes and in the slaying of Penelope's suitors. In L'incoronazione, Monteverdi represents moods and situations by specific musical devices: triple metre stands for the language of love; arpeggios demonstrate conflict; stile concitato represents rage. There is continuing debate about how much of the extant L'incoronazione music is Monteverdi's original, and how much is the work of others (there are, for instance, traces of music by Francesco Cavalli).",
"title": "Music"
},
{
"paragraph_id": 61,
"text": "The Selva morale e spirituale of 1641, and the posthumous Messa et salmi published in 1650 (which was edited by Cavalli), are selections of the sacred music that Monteverdi wrote for San Marco during his 30-year tenure – much else was likely written but not published. The Selva morale volume opens with a series of madrigal settings on moral texts, dwelling on themes such as \"the transitory nature of love, earthly rank and achievement, even existence itself\". They are followed by a Mass in conservative style (stile antico), the high point of which is an extended seven-voice \"Gloria\". Scholars believe that this might have been written to celebrate the end of the 1631 plague. The rest of the volume is made up of numerous psalm settings, two Magnificats and three Salve Reginas. The Messa et salmi volume includes a stile antico Mass for four voices, a polyphonic setting of the psalm Laetatus Sum, and a version of the Litany of Lareto that Monteverdi had originally published in 1620.",
"title": "Music"
},
{
"paragraph_id": 62,
"text": "The posthumous ninth book of madrigals was published in 1651, a miscellany dating back to the early 1630s, some items being repeats of previously published pieces, such as the popular duet O sia tranquillo il mare from 1638. The book includes a trio for three sopranos, \"Come dolce oggi l'auretta\", which is the only surviving music from the 1630 lost opera Proserpina rapita.",
"title": "Music"
},
{
"paragraph_id": 63,
"text": "In his lifetime Monteverdi enjoyed considerable status among musicians and the public. This is evidenced by the scale of his funeral rites: \"[W]ith truly royal pomp a catafalque was erected in the Chiesa de Padrini Minori de Frari, decorated all in mourning, but surrounded with so many candles that the church resembled a night sky luminous with stars\". This glorification was transitory; Carter writes that in Monteverdi's day, music rarely survived beyond the circumstances of its initial performance and was quickly forgotten along with its creator. In this regard Monteverdi fared better than most. His operatic works were revived in several cities in the decade following his death; according to Severo Bonini, writing in 1651, every musical household in Italy possessed a copy of the Lamento d'Arianna.",
"title": "Historical perspective"
},
{
"paragraph_id": 64,
"text": "The German composer Heinrich Schütz, who had studied in Venice under Giovanni Gabrieli shortly before Monteverdi's arrival there, possessed a copy of Il combattimento and himself took up elements of the stile concitato. On his second visit to Venice in 1628–1629, Arnold believes, Schütz absorbed the concepts of basso continuo and expressiveness of word-setting, but he opines that Schütz was more directly influenced by the style of the younger generation of Venetian composers, including Grandi and Giovanni Rovetta (the eventual successor to Monteverdi at San Marco). Schütz published a first book of Symphoniae sacrae, settings of biblical texts in the style of seconda pratica, in Venice in 1629. Es steh Gott auf, from his Symphoniae sacrae II, published in Dresden in 1647, contains specific quotations from Monteverdi.",
"title": "Historical perspective"
},
{
"paragraph_id": 65,
"text": "After the 1650s, Monteverdi's name quickly disappears from contemporary accounts, his music generally forgotten except for the Lamento, the prototype of a genre that would endure well into the 18th century.",
"title": "Historical perspective"
},
{
"paragraph_id": 66,
"text": "Interest in Monteverdi revived in the late 18th and early 19th centuries among music scholars in Germany and Italy, although he was still regarded as essentially a historical curiosity. Wider interest in the music itself began in 1881, when Robert Eitner published a shortened version of the Orfeo score. Around this time Kurt Vogel scored the madrigals from the original manuscripts, but more critical interest was shown in the operas, following the discovery of the L'incoronazione manuscript in 1888 and that of Il ritorno in 1904. Largely through the efforts of Vincent d'Indy, all three operas were staged in one form or another, during the first quarter of the 20th century: L'Orfeo in May 1911, L'incoronazione in February 1913 and Il ritorno in May 1925.",
"title": "Historical perspective"
},
{
"paragraph_id": 67,
"text": "The Italian nationalist poet Gabriele D'Annunzio lauded Monteverdi and in his novel Il fuoco (1900) wrote of \"il divino Claudio ... what a heroic soul, purely Italian in its essence!\" His vision of Monteverdi as the true founder of Italian musical lyricism was adopted by musicians who worked with the regime of Benito Mussolini (1922–1945), including Gian Francesco Malipiero, Luigi Dallapiccola, and Mario Labroca [it], who contrasted Monteverdi with the decadence of the music of Richard Strauss, Claude Debussy and Igor Stravinsky.",
"title": "Historical perspective"
},
{
"paragraph_id": 68,
"text": "In the years after the Second World War the operas began to be performed in the major opera houses, and eventually were established in the general repertory. The resuscitation of Monteverdi's sacred music took longer; he did not benefit from the Catholic Church's 19th-century revival of Renaissance music in the way that Palestrina did, perhaps, as Carter suggests, because Monteverdi was viewed chiefly as a secular composer. It was not until 1932 that the 1610 Vespers were published in a modern edition, followed by Redlich's revision two years later. Modern editions of the Selva morale and Missa e Salmi volumes were published respectively in 1940 and 1942.",
"title": "Historical perspective"
},
{
"paragraph_id": 69,
"text": "The revival of public interest in Monteverdi's music gathered pace in the second half of the 20th century, reaching full spate in the general early-music revival of the 1970s, during which time the emphasis turned increasingly towards \"authentic\" performance using historical instruments. The magazine Gramophone notes over 30 recordings of the Vespers between 1976 and 2011, and 27 of Il combattimento di Tancredi e Clorinda between 1971 and 2013. Monteverdi's surviving operas are today regularly performed; the website Operabase notes 555 performances of the operas in 149 productions worldwide in the seasons 2011–2016, ranking Monteverdi at 30th position for all composers, and at 8th ranking for Italian opera composers. In 1985, Manfred H. Stattkus published an index to Monteverdi's works, the Stattkus-Verzeichnis, (revised in 2006) giving each composition an \"SV\" number, to be used for cataloguing and references.",
"title": "Historical perspective"
},
{
"paragraph_id": 70,
"text": "Monteverdi is lauded by modern critics as \"the most significant composer in late Renaissance and early Baroque Italy\"; \"one of the principal composers in the history of Western music\"; and, routinely, as the first great opera composer. These assessments reflect a contemporary perspective, since his music was largely unknown to the composers who followed him during an extensive period, spanning more than two centuries after his death. It is, as Redlich and others have pointed out, the composers of the 20th and 21st century who have rediscovered Monteverdi and sought to make his music a basis for their own. Possibly, as Chew suggests, they are attracted by Monteverdi's reputation as \"a Modern, a breaker of rules, against the Ancients, those who deferred to ancient authority\" – although the composer was, essentially, a pragmatist, \"showing what can only be described as an opportunistic and eclectic willingness to use whatever lay to hand for the purpose\". In a letter dated 16 October 1633, Monteverdi appears to endorse the view of himself as a \"modern\": \"I would rather be moderately praised for the new style than greatly praised for the ordinary\". However, Chew, in his final summation, sees the composer historically as facing both ways, willing to use modern techniques but while at the same time protective of his status as a competent composer in the stile antico. Thus, says Chew, \"his achievement was both retrospective and progressive\". Monteverdi represents the late Renaissance era while simultaneously summing up much of the early Baroque. \"And in one respect in particular, his achievement was enduring: the effective projection of human emotions in music, in a way adequate for theatre as well as for chamber music.\"",
"title": "Historical perspective"
}
] | Claudio Giovanni Antonio Monteverdi was an Italian composer, choirmaster and string player. A composer of both secular and sacred music, and a pioneer in the development of opera, he is considered a crucial transitional figure between the Renaissance and Baroque periods of music history. Born in Cremona, where he undertook his first musical studies and compositions, Monteverdi developed his career first at the court of Mantua and then until his death in the Republic of Venice where he was maestro di cappella at the basilica of San Marco. His surviving letters give insight into the life of a professional musician in Italy of the period, including problems of income, patronage and politics. Much of Monteverdi's output, including many stage works, has been lost. His surviving music includes nine books of madrigals, large-scale religious works, such as his Vespro della Beata Vergine of 1610, and three complete operas. His opera L'Orfeo (1607) is the earliest of the genre still widely performed; towards the end of his life he wrote works for Venice, including Il ritorno d'Ulisse in patria and L'incoronazione di Poppea. While he worked extensively in the tradition of earlier Renaissance polyphony, as evidenced in his madrigals, he undertook great developments in form and melody, and began to employ the basso continuo technique, distinctive of the Baroque. No stranger to controversy, he defended his sometimes novel techniques as elements of a seconda pratica, contrasting with the more orthodox earlier style which he termed the prima pratica. Largely forgotten during the eighteenth and much of the nineteenth centuries, his works enjoyed a rediscovery around the beginning of the twentieth century. He is now established both as a significant influence in European musical history and as a composer whose works are regularly performed and recorded. | 2001-08-29T20:12:42Z | 2023-12-22T00:42:56Z | [
"Template:Cite news",
"Template:Subscription",
"Template:Refend",
"Template:Authority control",
"Template:JSTOR",
"Template:Cite AV media notes",
"Template:Cite web",
"Template:Listen",
"Template:Main",
"Template:Featured article",
"Template:C.",
"Template:Further",
"Template:Cite encyclopedia",
"Template:BBC composer page",
"Template:Claudio Monteverdi",
"Template:Navboxes",
"Template:Short description",
"Template:Redirect",
"Template:Ref begin",
"Template:Ill",
"Template:ChoralWiki",
"Template:Refn",
"Template:Cite journal",
"Template:Cite book",
"Template:IMSLP",
"Template:Subject bar",
"Template:Use dmy dates",
"Template:Reflist",
"Template:Harvp",
"Template:ISBN",
"Template:Lang",
"Template:' \"",
"Template:Webarchive"
] | https://en.wikipedia.org/wiki/Claudio_Monteverdi |
6,229 | Colossus computer | Colossus was a set of computers developed by British codebreakers in the years 1943–1945 to help in the cryptanalysis of the Lorenz cipher. Colossus used thermionic valves (vacuum tubes) to perform Boolean and counting operations. Colossus is thus regarded as the world's first programmable, electronic, digital computer, although it was programmed by switches and plugs and not by a stored program.
Colossus was designed by General Post Office (GPO) research telephone engineer Tommy Flowers to solve a problem posed by mathematician Max Newman at the Government Code and Cypher School (GC&CS) at Bletchley Park. Alan Turing's use of probability in cryptanalysis (see Banburismus) contributed to its design. It has sometimes been erroneously stated that Turing designed Colossus to aid the cryptanalysis of the Enigma. (Turing's machine that helped decode Enigma was the electromechanical Bombe, not Colossus.)
The prototype, Colossus Mark 1, was shown to be working in December 1943 and was in use at Bletchley Park by early 1944. An improved Colossus Mark 2 that used shift registers to quintuple the processing speed, first worked on 1 June 1944, just in time for the Normandy landings on D-Day. Ten Colossi were in use by the end of the war and an eleventh was being commissioned. Bletchley Park's use of these machines allowed the Allies to obtain a vast amount of high-level military intelligence from intercepted radiotelegraphy messages between the German High Command (OKW) and their army commands throughout occupied Europe.
The existence of the Colossus machines was kept secret until the mid-1970s. All but two machines were dismantled into such small parts that their use could not be inferred. The two retained machines were eventually dismantled in the 1960s. A functioning rebuild of a Mark 2 Colossus was completed in 2008 by Tony Sale and a team of volunteers; it is on display at The National Museum of Computing on Bletchley Park.
The Colossus computers were used to help decipher intercepted radio teleprinter messages that had been encrypted using an unknown device. Intelligence information revealed that the Germans called the wireless teleprinter transmission systems "Sägefisch" (sawfish). This led the British to call encrypted German teleprinter traffic "Fish", and the unknown machine and its intercepted messages "Tunny" (tunafish).
Before the Germans increased the security of their operating procedures, British cryptanalysts diagnosed how the unseen machine functioned and built an imitation of it called "British Tunny".
It was deduced that the machine had twelve wheels and used a Vernam ciphering technique on message characters in the standard 5-bit ITA2 telegraph code. It did this by combining the plaintext characters with a stream of key characters using the XOR Boolean function to produce the ciphertext.
In August 1941, a blunder by German operators led to the transmission of two versions of the same message with identical machine settings. These were intercepted and worked on at Bletchley Park. First, John Tiltman, a very talented GC&CS cryptanalyst, derived a key stream of almost 4000 characters. Then Bill Tutte, a newly arrived member of the Research Section, used this keystream to work out the logical structure of the Lorenz machine. He deduced that the twelve wheels consisted of two groups of five, which he named the χ (chi) and ψ (psi) wheels, the remaining two he called μ (mu) or "motor" wheels. The chi wheels stepped regularly with each letter that was encrypted, while the psi wheels stepped irregularly, under the control of the motor wheels.
With a sufficiently random keystream, a Vernam cipher removes the natural language property of a plaintext message of having an uneven frequency distribution of the different characters, to produce a uniform distribution in the ciphertext. The Tunny machine did this well. However, the cryptanalysts worked out that by examining the frequency distribution of the character-to-character changes in the ciphertext, instead of the plain characters, there was a departure from uniformity which provided a way into the system. This was achieved by "differencing" in which each bit or character was XOR-ed with its successor. After Germany surrendered, allied forces captured a Tunny machine and discovered that it was the electromechanical Lorenz SZ (Schlüsselzusatzgerät, cipher attachment) in-line cipher machine.
In order to decrypt the transmitted messages, two tasks had to be performed. The first was "wheel breaking", which was the discovery of the cam patterns for all the wheels. These patterns were set up on the Lorenz machine and then used for a fixed period of time for a succession of different messages. Each transmission, which often contained more than one message, was enciphered with a different start position of the wheels. Alan Turing invented a method of wheel-breaking that became known as Turingery. Turing's technique was further developed into "Rectangling", for which Colossus could produce tables for manual analysis. Colossi 2, 4, 6, 7 and 9 had a "gadget" to aid this process.
The second task was "wheel setting", which worked out the start positions of the wheels for a particular message and could only be attempted once the cam patterns were known. It was this task for which Colossus was initially designed. To discover the start position of the chi wheels for a message, Colossus compared two character streams, counting statistics from the evaluation of programmable Boolean functions. The two streams were the ciphertext, which was read at high speed from a paper tape, and the keystream, which was generated internally, in a simulation of the unknown German machine. After a succession of different Colossus runs to discover the likely chi-wheel settings, they were checked by examining the frequency distribution of the characters in the processed ciphertext. Colossus produced these frequency counts.
By using differencing and knowing that the psi wheels did not advance with each character, Tutte worked out that trying just two differenced bits (impulses) of the chi-stream against the differenced ciphertext would produce a statistic that was non-random. This became known as Tutte's "1+2 break in". It involved calculating the following Boolean function:
and counting the number of times it yielded "false" (zero). If this number exceeded a pre-defined threshold value known as the "set total", it was printed out. The cryptanalyst would examine the printout to determine which of the putative start positions was most likely to be the correct one for the chi-1 and chi-2 wheels.
This technique would then be applied to other pairs of, or single, impulses to determine the likely start position of all five chi wheels. From this, the de-chi (D) of a ciphertext could be obtained, from which the psi component could be removed by manual methods. If the frequency distribution of characters in the de-chi version of the ciphertext was within certain bounds, "wheel setting" of the chi wheels was considered to have been achieved, and the message settings and de-chi were passed to the "Testery". This was the section at Bletchley Park led by Major Ralph Tester where the bulk of the decrypting work was done by manual and linguistic methods.
Colossus could also derive the start position of the psi and motor wheels. The feasibility of utilizing this additional capability regularly was made possible in the last few months of the war when there were plenty of Colossi available and the number of Tunny messages had declined.
Colossus was developed for the "Newmanry", the section headed by the mathematician Max Newman that was responsible for machine methods against the twelve-rotor Lorenz SZ40/42 on-line teleprinter cipher machine (code-named Tunny, for tunafish). The Colossus design arose out of a prior project that produced a counting machine dubbed "Heath Robinson". Although it proved the concept of machine analysis for this part of the process, it was initially unreliable. The electro-mechanical parts were relatively slow and it was difficult to synchronise two looped paper tapes, one containing the enciphered message, and the other representing part of the keystream of the Lorenz machine, also the tapes tended to stretch when being read at up to 2000 characters per second.
Tommy Flowers MBE was a senior electrical engineer and Head of the Switching Group at the Post Office Research Station at Dollis Hill. Prior to his work on Colossus, he had been involved with GC&CS at Bletchley Park from February 1941 in an attempt to improve the Bombes that were used in the cryptanalysis of the German Enigma cipher machine. He was recommended to Max Newman by Alan Turing, who had been impressed by his work on the Bombes. The main components of the Heath Robinson machine were as follows.
Flowers had been brought in to design the Heath Robinson's combining unit. He was not impressed by the system of a key tape that had to be kept synchronised with the message tape and, on his own initiative, he designed an electronic machine which eliminated the need for the key tape by having an electronic analogue of the Lorenz (Tunny) machine. He presented this design to Max Newman in February 1943, but the idea that the one to two thousand thermionic valves (vacuum tubes and thyratrons) proposed, could work together reliably, was greeted with great scepticism, so more Robinsons were ordered from Dollis Hill. Flowers, however, knew from his pre-war work that most thermionic valve failures occurred as a result of the thermal stresses at power-up, so not powering a machine down reduced failure rates to very low levels. Additionally, if the heaters were started at a low voltage then slowly brought up to full voltage, thermal stress was reduced. The valves themselves could be soldered-in to avoid problems with plug-in bases, which could be unreliable. Flowers persisted with the idea and obtained support from the Director of the Research Station, W Gordon Radley.
Flowers and his team of some fifty people in the switching group spent eleven months from early February 1943 designing and building a machine that dispensed with the second tape of the Heath Robinson, by generating the wheel patterns electronically. Flowers used some of his own money for the project. This prototype, Mark 1 Colossus, contained 1,600 thermionic valves (tubes). It performed satisfactorily at Dollis Hill on 8 December 1943 and was dismantled and shipped to Bletchley Park, where it was delivered on 18 January and re-assembled by Harry Fensom and Don Horwood. It was operational in January and it successfully attacked its first message on 5 February 1944. It was a large structure and was dubbed 'Colossus', supposedly by the WRNS operators. However, a memo held in the National Archives written by Max Newman on 18 January 1944 records that 'Colossus arrives today".
During the development of the prototype, an improved design had been developed – the Mark 2 Colossus. Four of these were ordered in March 1944 and by the end of April the number on order had been increased to twelve. Dollis Hill was put under pressure to have the first of these working by 1 June. Allen Coombs took over leadership of the production Mark 2 Colossi, the first of which – containing 2,400 valves – became operational at 08:00 on 1 June 1944, just in time for the Allied Invasion of Normandy on D-Day. Subsequently, Colossi were delivered at the rate of about one a month. By the time of V-E Day there were ten Colossi working at Bletchley Park and a start had been made on assembling an eleventh.
The main units of the Mark 2 design were as follows.
Most of the design of the electronics was the work of Tommy Flowers, assisted by William Chandler, Sidney Broadhurst and Allen Coombs; with Erie Speight and Arnold Lynch developing the photoelectric reading mechanism. Coombs remembered Flowers, having produced a rough draft of his design, tearing it into pieces that he handed out to his colleagues for them to do the detailed design and get their team to manufacture it. The Mark 2 Colossi were both five times faster and were simpler to operate than the prototype.
Data input to Colossus was by photoelectric reading of a paper tape transcription of the enciphered intercepted message. This was arranged in a continuous loop so that it could be read and re-read multiple times – there being no internal storage for the data. The design overcame the problem of synchronizing the electronics with the speed of the message tape by generating a clock signal from reading its sprocket holes. The speed of operation was thus limited by the mechanics of reading the tape. During development, the tape reader was tested up to 9700 characters per second (53 mph) before the tape disintegrated. So 5000 characters/second (40 ft/s (12.2 m/s; 27.3 mph)) was settled on as the speed for regular use. Flowers designed a 6-character shift register, which was used both for computing the delta function (ΔZ) and for testing five different possible starting points of Tunny's wheels in the five processors. This five-way parallelism enabled five simultaneous tests and counts to be performed giving an effective processing speed of 25,000 characters per second. The computation used algorithms devised by W. T. Tutte and colleagues to decrypt a Tunny message.
The Newmanry was staffed by cryptanalysts, operators from the Women's Royal Naval Service (WRNS) – known as "Wrens" – and engineers who were permanently on hand for maintenance and repair. By the end of the war the staffing was 272 Wrens and 27 men.
The first job in operating Colossus for a new message was to prepare the paper tape loop. This was performed by the Wrens who stuck the two ends together using Bostik glue, ensuring that there was a 150-character length of blank tape between the end and the start of the message. Using a special hand punch they inserted a start hole between the third and fourth channels 2+1⁄2 sprocket holes from the end of the blank section, and a stop hole between the fourth and fifth channels 1+1⁄2 sprocket holes from the end of the characters of the message. These were read by specially positioned photocells and indicated when the message was about to start and when it ended. The operator would then thread the paper tape through the gate and around the pulleys of the bedstead and adjust the tension. The two-tape bedstead design had been carried on from Heath Robinson so that one tape could be loaded whilst the previous one was being run. A switch on the Selection Panel specified the "near" or the "far" tape.
After performing various resetting and zeroizing tasks, the Wren operators would, under instruction from the cryptanalyst, operate the "set total" decade switches and the K2 panel switches to set the desired algorithm. They would then start the bedstead tape motor and lamp and, when the tape was up to speed, operate the master start switch.
By VE-Day with ten Colossi, seven were used for "wheel setting" and 3 for "wheel breaking".
Howard Campaigne, a mathematician and cryptanalyst from the US Navy's OP-20-G, wrote the following in a foreword to Flowers' 1983 paper "The Design of Colossus".
My view of Colossus was that of cryptanalyst-programmer. I told the machine to make certain calculations and counts, and after studying the results, told it to do another job. It did not remember the previous result, nor could it have acted upon it if it did. Colossus and I alternated in an interaction that sometimes achieved an analysis of an unusual German cipher system, called "Geheimschreiber" by the Germans, and "Fish" by the cryptanalysts.
Colossus was not a stored-program computer. The input data for the five parallel processors was read from the looped message paper tape and the electronic pattern generators for the chi, psi and motor wheels. The programs for the processors were set and held on the switches and jack panel connections. Each processor could evaluate a Boolean function and count and display the number of times it yielded the specified value of "false" (0) or "true" (1) for each pass of the message tape.
Input to the processors came from two sources, the shift registers from tape reading and the thyratron rings that emulated the wheels of the Tunny machine. The characters on the paper tape were called Z and the characters from the Tunny emulator were referred to by the Greek letters that Bill Tutte had given them when working out the logical structure of the machine. On the selection panel, switches specified either Z or ΔZ, either χ {\displaystyle \chi } or Δ χ {\displaystyle \chi } and either ψ {\displaystyle \psi } or Δ ψ {\displaystyle \psi } for the data to be passed to the jack field and 'K2 switch panel'. These signals from the wheel simulators could be specified as stepping on with each new pass of the message tape or not.
The K2 switch panel had a group of switches on the left-hand side to specify the algorithm. The switches on the right-hand side selected the counter to which the result was fed. The plugboard allowed less specialized conditions to be imposed. Overall the K2 switch panel switches and the plugboard allowed about five billion different combinations of the selected variables.
As an example: a set of runs for a message tape might initially involve two chi wheels, as in Tutte's 1+2 algorithm. Such a two-wheel run was called a long run, taking on average eight minutes unless the parallelism was utilised to cut the time by a factor of five. The subsequent runs might only involve setting one chi wheel, giving a short run taking about two minutes. Initially, after the initial long run, the choice of the next algorithm to be tried was specified by the cryptanalyst. Experience showed, however, that decision trees for this iterative process could be produced for use by the Wren operators in a proportion of cases.
Although the Colossus was the first of the electronic digital machines with programmability, albeit limited by modern standards, it was not a general-purpose machine, being designed for a range of cryptanalytic tasks, most involving counting the results of evaluating Boolean algorithms.
A Colossus computer was thus not a fully Turing complete machine. However, University of San Francisco professor Benjamin Wells has shown that if all ten Colossus machines made were rearranged in a specific cluster, then the entire set of computers could have simulated a universal Turing machine, and thus be Turing complete.
Colossus and the reasons for its construction were highly secret and remained so for 30 years after the War. Consequently, it was not included in the history of computing hardware for many years, and Flowers and his associates were deprived of the recognition they were due. Colossi 1 to 10 were dismantled after the war and parts returned to the Post Office. Some parts, sanitised as to their original purpose, were taken to Max Newman's Royal Society Computing Machine Laboratory at Manchester University. Tommy Flowers was ordered to destroy all documentation and burnt them in a furnace at Dollis Hill. He later said of that order:
That was a terrible mistake. I was instructed to destroy all the records, which I did. I took all the drawings and the plans and all the information about Colossus on paper and put it in the boiler fire. And saw it burn.
Colossi 11 and 12, along with two replica Tunny machines, were retained, being moved to GCHQ's new headquarters at Eastcote in April 1946, and again with GCHQ to Cheltenham between 1952 and 1954. One of the Colossi, known as Colossus Blue, was dismantled in 1959; the other in 1960. There had been attempts to adapt them to other purposes, with varying success; in their later years they had been used for training. Jack Good related how he was the first to use Colossus after the war, persuading the US National Security Agency that it could be used to perform a function for which they were planning to build a special-purpose machine. Colossus was also used to perform character counts on one-time pad tape to test for non-randomness.
A small number of people who were associated with Colossus—and knew that large-scale, reliable, high-speed electronic digital computing devices were feasible—played significant roles in early computer work in the UK and probably in the US. However, being so secret, it had little direct influence on the development of later computers; it was EDVAC that was the seminal computer architecture of the time. In 1972, Herman Goldstine, who was unaware of Colossus and its legacy to the projects of people such as Alan Turing (ACE), Max Newman (Manchester computers) and Harry Huskey (Bendix G-15), wrote that,
Britain had such vitality that it could immediately after the war embark on so many well-conceived and well-executed projects in the computer field.
Professor Brian Randell, who unearthed information about Colossus in the 1970s, commented on this, saying that:
It is my opinion that the COLOSSUS project was an important source of this vitality, one that has been largely unappreciated, as has the significance of its places in the chronology of the invention of the digital computer.
Randell's efforts started to bear fruit in the mid-1970s. The secrecy about Bletchley Park had been broken when Group Captain Winterbotham published his book The Ultra Secret in 1974. Randell was researching the history of computer science in Britain for a conference on the history of computing held at the Los Alamos Scientific Laboratory, New Mexico on 10-15 June 1976, and got permission to present a paper on wartime development of the COLOSSI at the Post Office Research Station, Dollis Hill (in October 1975 the British Government had released a series of captioned photographs from the Public Record Office). The interest in the “revelations” in his paper resulted in a special evening meeting when Randell and Coombs answered further questions. Coombs later wrote that no member of our team could ever forget the fellowship, the sense of purpose and, above all, the breathless excitement of those days. In 1977 Randell published an article The First Electronic Computer in several journals.
In October 2000, a 500-page technical report on the Tunny cipher and its cryptanalysis—entitled General Report on Tunny—was released by GCHQ to the national Public Record Office, and it contains a fascinating paean to Colossus by the cryptographers who worked with it:
It is regretted that it is not possible to give an adequate idea of the fascination of a Colossus at work; its sheer bulk and apparent complexity; the fantastic speed of thin paper tape round the glittering pulleys; the childish pleasure of not-not, span, print main header and other gadgets; the wizardry of purely mechanical decoding letter by letter (one novice thought she was being hoaxed); the uncanny action of the typewriter in printing the correct scores without and beyond human aid; the stepping of the display; periods of eager expectation culminating in the sudden appearance of the longed-for score; and the strange rhythms characterizing every type of run: the stately break-in, the erratic short run, the regularity of wheel-breaking, the stolid rectangle interrupted by the wild leaps of the carriage-return, the frantic chatter of a motor run, even the ludicrous frenzy of hosts of bogus scores.
Construction of a fully functional rebuild of a Colossus Mark 2 was undertaken between 1993 and 2008 by a team led by Tony Sale. In spite of the blueprints and hardware being destroyed, a surprising amount of material survived, mainly in engineers' notebooks, but a considerable amount of it in the U.S. The optical tape reader might have posed the biggest problem, but Dr. Arnold Lynch, its original designer was able to redesign it to his own original specification. The reconstruction is on display, in the historically correct place for Colossus No. 9, at The National Museum of Computing, in H Block Bletchley Park in Milton Keynes, Buckinghamshire.
In November 2007, to celebrate the project completion and to mark the start of a fundraising initiative for The National Museum of Computing, a Cipher Challenge pitted the rebuilt Colossus against radio amateurs worldwide in being first to receive and decode three messages enciphered using the Lorenz SZ42 and transmitted from radio station DL0HNF in the Heinz Nixdorf MuseumsForum computer museum. The challenge was easily won by radio amateur Joachim Schüth, who had carefully prepared for the event and developed his own signal processing and code-breaking code using Ada. The Colossus team were hampered by their wish to use World War II radio equipment, delaying them by a day because of poor reception conditions. Nevertheless, the victor's 1.4 GHz laptop, running his own code, took less than a minute to find the settings for all 12 wheels. The German codebreaker said: "My laptop digested ciphertext at a speed of 1.2 million characters per second—240 times faster than Colossus. If you scale the CPU frequency by that factor, you get an equivalent clock of 5.8 MHz for Colossus. That is a remarkable speed for a computer built in 1944."
The Cipher Challenge verified the successful completion of the rebuild project. "On the strength of today's performance Colossus is as good as it was six decades ago", commented Tony Sale. "We are delighted to have produced a fitting tribute to the people who worked at Bletchley Park and whose brainpower devised these fantastic machines which broke these ciphers and shortened the war by many months."
There was a fictional computer named Colossus in the 1970 film Colossus: The Forbin Project which was based on the 1966 novel Colossus by D. F. Jones. This was a coincidence as it pre-dates the public release of information about Colossus, or even its name.
Neal Stephenson's novel Cryptonomicon (1999) also contains a fictional treatment of the historical role played by Turing and Bletchley Park. | [
{
"paragraph_id": 0,
"text": "Colossus was a set of computers developed by British codebreakers in the years 1943–1945 to help in the cryptanalysis of the Lorenz cipher. Colossus used thermionic valves (vacuum tubes) to perform Boolean and counting operations. Colossus is thus regarded as the world's first programmable, electronic, digital computer, although it was programmed by switches and plugs and not by a stored program.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Colossus was designed by General Post Office (GPO) research telephone engineer Tommy Flowers to solve a problem posed by mathematician Max Newman at the Government Code and Cypher School (GC&CS) at Bletchley Park. Alan Turing's use of probability in cryptanalysis (see Banburismus) contributed to its design. It has sometimes been erroneously stated that Turing designed Colossus to aid the cryptanalysis of the Enigma. (Turing's machine that helped decode Enigma was the electromechanical Bombe, not Colossus.)",
"title": ""
},
{
"paragraph_id": 2,
"text": "The prototype, Colossus Mark 1, was shown to be working in December 1943 and was in use at Bletchley Park by early 1944. An improved Colossus Mark 2 that used shift registers to quintuple the processing speed, first worked on 1 June 1944, just in time for the Normandy landings on D-Day. Ten Colossi were in use by the end of the war and an eleventh was being commissioned. Bletchley Park's use of these machines allowed the Allies to obtain a vast amount of high-level military intelligence from intercepted radiotelegraphy messages between the German High Command (OKW) and their army commands throughout occupied Europe.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The existence of the Colossus machines was kept secret until the mid-1970s. All but two machines were dismantled into such small parts that their use could not be inferred. The two retained machines were eventually dismantled in the 1960s. A functioning rebuild of a Mark 2 Colossus was completed in 2008 by Tony Sale and a team of volunteers; it is on display at The National Museum of Computing on Bletchley Park.",
"title": ""
},
{
"paragraph_id": 4,
"text": "The Colossus computers were used to help decipher intercepted radio teleprinter messages that had been encrypted using an unknown device. Intelligence information revealed that the Germans called the wireless teleprinter transmission systems \"Sägefisch\" (sawfish). This led the British to call encrypted German teleprinter traffic \"Fish\", and the unknown machine and its intercepted messages \"Tunny\" (tunafish).",
"title": "Purpose and origins"
},
{
"paragraph_id": 5,
"text": "Before the Germans increased the security of their operating procedures, British cryptanalysts diagnosed how the unseen machine functioned and built an imitation of it called \"British Tunny\".",
"title": "Purpose and origins"
},
{
"paragraph_id": 6,
"text": "It was deduced that the machine had twelve wheels and used a Vernam ciphering technique on message characters in the standard 5-bit ITA2 telegraph code. It did this by combining the plaintext characters with a stream of key characters using the XOR Boolean function to produce the ciphertext.",
"title": "Purpose and origins"
},
{
"paragraph_id": 7,
"text": "In August 1941, a blunder by German operators led to the transmission of two versions of the same message with identical machine settings. These were intercepted and worked on at Bletchley Park. First, John Tiltman, a very talented GC&CS cryptanalyst, derived a key stream of almost 4000 characters. Then Bill Tutte, a newly arrived member of the Research Section, used this keystream to work out the logical structure of the Lorenz machine. He deduced that the twelve wheels consisted of two groups of five, which he named the χ (chi) and ψ (psi) wheels, the remaining two he called μ (mu) or \"motor\" wheels. The chi wheels stepped regularly with each letter that was encrypted, while the psi wheels stepped irregularly, under the control of the motor wheels.",
"title": "Purpose and origins"
},
{
"paragraph_id": 8,
"text": "With a sufficiently random keystream, a Vernam cipher removes the natural language property of a plaintext message of having an uneven frequency distribution of the different characters, to produce a uniform distribution in the ciphertext. The Tunny machine did this well. However, the cryptanalysts worked out that by examining the frequency distribution of the character-to-character changes in the ciphertext, instead of the plain characters, there was a departure from uniformity which provided a way into the system. This was achieved by \"differencing\" in which each bit or character was XOR-ed with its successor. After Germany surrendered, allied forces captured a Tunny machine and discovered that it was the electromechanical Lorenz SZ (Schlüsselzusatzgerät, cipher attachment) in-line cipher machine.",
"title": "Purpose and origins"
},
{
"paragraph_id": 9,
"text": "In order to decrypt the transmitted messages, two tasks had to be performed. The first was \"wheel breaking\", which was the discovery of the cam patterns for all the wheels. These patterns were set up on the Lorenz machine and then used for a fixed period of time for a succession of different messages. Each transmission, which often contained more than one message, was enciphered with a different start position of the wheels. Alan Turing invented a method of wheel-breaking that became known as Turingery. Turing's technique was further developed into \"Rectangling\", for which Colossus could produce tables for manual analysis. Colossi 2, 4, 6, 7 and 9 had a \"gadget\" to aid this process.",
"title": "Purpose and origins"
},
{
"paragraph_id": 10,
"text": "The second task was \"wheel setting\", which worked out the start positions of the wheels for a particular message and could only be attempted once the cam patterns were known. It was this task for which Colossus was initially designed. To discover the start position of the chi wheels for a message, Colossus compared two character streams, counting statistics from the evaluation of programmable Boolean functions. The two streams were the ciphertext, which was read at high speed from a paper tape, and the keystream, which was generated internally, in a simulation of the unknown German machine. After a succession of different Colossus runs to discover the likely chi-wheel settings, they were checked by examining the frequency distribution of the characters in the processed ciphertext. Colossus produced these frequency counts.",
"title": "Purpose and origins"
},
{
"paragraph_id": 11,
"text": "By using differencing and knowing that the psi wheels did not advance with each character, Tutte worked out that trying just two differenced bits (impulses) of the chi-stream against the differenced ciphertext would produce a statistic that was non-random. This became known as Tutte's \"1+2 break in\". It involved calculating the following Boolean function:",
"title": "Decryption processes"
},
{
"paragraph_id": 12,
"text": "and counting the number of times it yielded \"false\" (zero). If this number exceeded a pre-defined threshold value known as the \"set total\", it was printed out. The cryptanalyst would examine the printout to determine which of the putative start positions was most likely to be the correct one for the chi-1 and chi-2 wheels.",
"title": "Decryption processes"
},
{
"paragraph_id": 13,
"text": "This technique would then be applied to other pairs of, or single, impulses to determine the likely start position of all five chi wheels. From this, the de-chi (D) of a ciphertext could be obtained, from which the psi component could be removed by manual methods. If the frequency distribution of characters in the de-chi version of the ciphertext was within certain bounds, \"wheel setting\" of the chi wheels was considered to have been achieved, and the message settings and de-chi were passed to the \"Testery\". This was the section at Bletchley Park led by Major Ralph Tester where the bulk of the decrypting work was done by manual and linguistic methods.",
"title": "Decryption processes"
},
{
"paragraph_id": 14,
"text": "Colossus could also derive the start position of the psi and motor wheels. The feasibility of utilizing this additional capability regularly was made possible in the last few months of the war when there were plenty of Colossi available and the number of Tunny messages had declined.",
"title": "Decryption processes"
},
{
"paragraph_id": 15,
"text": "Colossus was developed for the \"Newmanry\", the section headed by the mathematician Max Newman that was responsible for machine methods against the twelve-rotor Lorenz SZ40/42 on-line teleprinter cipher machine (code-named Tunny, for tunafish). The Colossus design arose out of a prior project that produced a counting machine dubbed \"Heath Robinson\". Although it proved the concept of machine analysis for this part of the process, it was initially unreliable. The electro-mechanical parts were relatively slow and it was difficult to synchronise two looped paper tapes, one containing the enciphered message, and the other representing part of the keystream of the Lorenz machine, also the tapes tended to stretch when being read at up to 2000 characters per second.",
"title": "Design and construction"
},
{
"paragraph_id": 16,
"text": "Tommy Flowers MBE was a senior electrical engineer and Head of the Switching Group at the Post Office Research Station at Dollis Hill. Prior to his work on Colossus, he had been involved with GC&CS at Bletchley Park from February 1941 in an attempt to improve the Bombes that were used in the cryptanalysis of the German Enigma cipher machine. He was recommended to Max Newman by Alan Turing, who had been impressed by his work on the Bombes. The main components of the Heath Robinson machine were as follows.",
"title": "Design and construction"
},
{
"paragraph_id": 17,
"text": "Flowers had been brought in to design the Heath Robinson's combining unit. He was not impressed by the system of a key tape that had to be kept synchronised with the message tape and, on his own initiative, he designed an electronic machine which eliminated the need for the key tape by having an electronic analogue of the Lorenz (Tunny) machine. He presented this design to Max Newman in February 1943, but the idea that the one to two thousand thermionic valves (vacuum tubes and thyratrons) proposed, could work together reliably, was greeted with great scepticism, so more Robinsons were ordered from Dollis Hill. Flowers, however, knew from his pre-war work that most thermionic valve failures occurred as a result of the thermal stresses at power-up, so not powering a machine down reduced failure rates to very low levels. Additionally, if the heaters were started at a low voltage then slowly brought up to full voltage, thermal stress was reduced. The valves themselves could be soldered-in to avoid problems with plug-in bases, which could be unreliable. Flowers persisted with the idea and obtained support from the Director of the Research Station, W Gordon Radley.",
"title": "Design and construction"
},
{
"paragraph_id": 18,
"text": "Flowers and his team of some fifty people in the switching group spent eleven months from early February 1943 designing and building a machine that dispensed with the second tape of the Heath Robinson, by generating the wheel patterns electronically. Flowers used some of his own money for the project. This prototype, Mark 1 Colossus, contained 1,600 thermionic valves (tubes). It performed satisfactorily at Dollis Hill on 8 December 1943 and was dismantled and shipped to Bletchley Park, where it was delivered on 18 January and re-assembled by Harry Fensom and Don Horwood. It was operational in January and it successfully attacked its first message on 5 February 1944. It was a large structure and was dubbed 'Colossus', supposedly by the WRNS operators. However, a memo held in the National Archives written by Max Newman on 18 January 1944 records that 'Colossus arrives today\".",
"title": "Design and construction"
},
{
"paragraph_id": 19,
"text": "During the development of the prototype, an improved design had been developed – the Mark 2 Colossus. Four of these were ordered in March 1944 and by the end of April the number on order had been increased to twelve. Dollis Hill was put under pressure to have the first of these working by 1 June. Allen Coombs took over leadership of the production Mark 2 Colossi, the first of which – containing 2,400 valves – became operational at 08:00 on 1 June 1944, just in time for the Allied Invasion of Normandy on D-Day. Subsequently, Colossi were delivered at the rate of about one a month. By the time of V-E Day there were ten Colossi working at Bletchley Park and a start had been made on assembling an eleventh.",
"title": "Design and construction"
},
{
"paragraph_id": 20,
"text": "The main units of the Mark 2 design were as follows.",
"title": "Design and construction"
},
{
"paragraph_id": 21,
"text": "Most of the design of the electronics was the work of Tommy Flowers, assisted by William Chandler, Sidney Broadhurst and Allen Coombs; with Erie Speight and Arnold Lynch developing the photoelectric reading mechanism. Coombs remembered Flowers, having produced a rough draft of his design, tearing it into pieces that he handed out to his colleagues for them to do the detailed design and get their team to manufacture it. The Mark 2 Colossi were both five times faster and were simpler to operate than the prototype.",
"title": "Design and construction"
},
{
"paragraph_id": 22,
"text": "Data input to Colossus was by photoelectric reading of a paper tape transcription of the enciphered intercepted message. This was arranged in a continuous loop so that it could be read and re-read multiple times – there being no internal storage for the data. The design overcame the problem of synchronizing the electronics with the speed of the message tape by generating a clock signal from reading its sprocket holes. The speed of operation was thus limited by the mechanics of reading the tape. During development, the tape reader was tested up to 9700 characters per second (53 mph) before the tape disintegrated. So 5000 characters/second (40 ft/s (12.2 m/s; 27.3 mph)) was settled on as the speed for regular use. Flowers designed a 6-character shift register, which was used both for computing the delta function (ΔZ) and for testing five different possible starting points of Tunny's wheels in the five processors. This five-way parallelism enabled five simultaneous tests and counts to be performed giving an effective processing speed of 25,000 characters per second. The computation used algorithms devised by W. T. Tutte and colleagues to decrypt a Tunny message.",
"title": "Design and construction"
},
{
"paragraph_id": 23,
"text": "The Newmanry was staffed by cryptanalysts, operators from the Women's Royal Naval Service (WRNS) – known as \"Wrens\" – and engineers who were permanently on hand for maintenance and repair. By the end of the war the staffing was 272 Wrens and 27 men.",
"title": "Operation"
},
{
"paragraph_id": 24,
"text": "The first job in operating Colossus for a new message was to prepare the paper tape loop. This was performed by the Wrens who stuck the two ends together using Bostik glue, ensuring that there was a 150-character length of blank tape between the end and the start of the message. Using a special hand punch they inserted a start hole between the third and fourth channels 2+1⁄2 sprocket holes from the end of the blank section, and a stop hole between the fourth and fifth channels 1+1⁄2 sprocket holes from the end of the characters of the message. These were read by specially positioned photocells and indicated when the message was about to start and when it ended. The operator would then thread the paper tape through the gate and around the pulleys of the bedstead and adjust the tension. The two-tape bedstead design had been carried on from Heath Robinson so that one tape could be loaded whilst the previous one was being run. A switch on the Selection Panel specified the \"near\" or the \"far\" tape.",
"title": "Operation"
},
{
"paragraph_id": 25,
"text": "After performing various resetting and zeroizing tasks, the Wren operators would, under instruction from the cryptanalyst, operate the \"set total\" decade switches and the K2 panel switches to set the desired algorithm. They would then start the bedstead tape motor and lamp and, when the tape was up to speed, operate the master start switch.",
"title": "Operation"
},
{
"paragraph_id": 26,
"text": "By VE-Day with ten Colossi, seven were used for \"wheel setting\" and 3 for \"wheel breaking\".",
"title": "Operation"
},
{
"paragraph_id": 27,
"text": "Howard Campaigne, a mathematician and cryptanalyst from the US Navy's OP-20-G, wrote the following in a foreword to Flowers' 1983 paper \"The Design of Colossus\".",
"title": "Programming"
},
{
"paragraph_id": 28,
"text": "My view of Colossus was that of cryptanalyst-programmer. I told the machine to make certain calculations and counts, and after studying the results, told it to do another job. It did not remember the previous result, nor could it have acted upon it if it did. Colossus and I alternated in an interaction that sometimes achieved an analysis of an unusual German cipher system, called \"Geheimschreiber\" by the Germans, and \"Fish\" by the cryptanalysts.",
"title": "Programming"
},
{
"paragraph_id": 29,
"text": "Colossus was not a stored-program computer. The input data for the five parallel processors was read from the looped message paper tape and the electronic pattern generators for the chi, psi and motor wheels. The programs for the processors were set and held on the switches and jack panel connections. Each processor could evaluate a Boolean function and count and display the number of times it yielded the specified value of \"false\" (0) or \"true\" (1) for each pass of the message tape.",
"title": "Programming"
},
{
"paragraph_id": 30,
"text": "Input to the processors came from two sources, the shift registers from tape reading and the thyratron rings that emulated the wheels of the Tunny machine. The characters on the paper tape were called Z and the characters from the Tunny emulator were referred to by the Greek letters that Bill Tutte had given them when working out the logical structure of the machine. On the selection panel, switches specified either Z or ΔZ, either χ {\\displaystyle \\chi } or Δ χ {\\displaystyle \\chi } and either ψ {\\displaystyle \\psi } or Δ ψ {\\displaystyle \\psi } for the data to be passed to the jack field and 'K2 switch panel'. These signals from the wheel simulators could be specified as stepping on with each new pass of the message tape or not.",
"title": "Programming"
},
{
"paragraph_id": 31,
"text": "The K2 switch panel had a group of switches on the left-hand side to specify the algorithm. The switches on the right-hand side selected the counter to which the result was fed. The plugboard allowed less specialized conditions to be imposed. Overall the K2 switch panel switches and the plugboard allowed about five billion different combinations of the selected variables.",
"title": "Programming"
},
{
"paragraph_id": 32,
"text": "As an example: a set of runs for a message tape might initially involve two chi wheels, as in Tutte's 1+2 algorithm. Such a two-wheel run was called a long run, taking on average eight minutes unless the parallelism was utilised to cut the time by a factor of five. The subsequent runs might only involve setting one chi wheel, giving a short run taking about two minutes. Initially, after the initial long run, the choice of the next algorithm to be tried was specified by the cryptanalyst. Experience showed, however, that decision trees for this iterative process could be produced for use by the Wren operators in a proportion of cases.",
"title": "Programming"
},
{
"paragraph_id": 33,
"text": "Although the Colossus was the first of the electronic digital machines with programmability, albeit limited by modern standards, it was not a general-purpose machine, being designed for a range of cryptanalytic tasks, most involving counting the results of evaluating Boolean algorithms.",
"title": "Influence and fate"
},
{
"paragraph_id": 34,
"text": "A Colossus computer was thus not a fully Turing complete machine. However, University of San Francisco professor Benjamin Wells has shown that if all ten Colossus machines made were rearranged in a specific cluster, then the entire set of computers could have simulated a universal Turing machine, and thus be Turing complete.",
"title": "Influence and fate"
},
{
"paragraph_id": 35,
"text": "Colossus and the reasons for its construction were highly secret and remained so for 30 years after the War. Consequently, it was not included in the history of computing hardware for many years, and Flowers and his associates were deprived of the recognition they were due. Colossi 1 to 10 were dismantled after the war and parts returned to the Post Office. Some parts, sanitised as to their original purpose, were taken to Max Newman's Royal Society Computing Machine Laboratory at Manchester University. Tommy Flowers was ordered to destroy all documentation and burnt them in a furnace at Dollis Hill. He later said of that order:",
"title": "Influence and fate"
},
{
"paragraph_id": 36,
"text": "That was a terrible mistake. I was instructed to destroy all the records, which I did. I took all the drawings and the plans and all the information about Colossus on paper and put it in the boiler fire. And saw it burn.",
"title": "Influence and fate"
},
{
"paragraph_id": 37,
"text": "Colossi 11 and 12, along with two replica Tunny machines, were retained, being moved to GCHQ's new headquarters at Eastcote in April 1946, and again with GCHQ to Cheltenham between 1952 and 1954. One of the Colossi, known as Colossus Blue, was dismantled in 1959; the other in 1960. There had been attempts to adapt them to other purposes, with varying success; in their later years they had been used for training. Jack Good related how he was the first to use Colossus after the war, persuading the US National Security Agency that it could be used to perform a function for which they were planning to build a special-purpose machine. Colossus was also used to perform character counts on one-time pad tape to test for non-randomness.",
"title": "Influence and fate"
},
{
"paragraph_id": 38,
"text": "A small number of people who were associated with Colossus—and knew that large-scale, reliable, high-speed electronic digital computing devices were feasible—played significant roles in early computer work in the UK and probably in the US. However, being so secret, it had little direct influence on the development of later computers; it was EDVAC that was the seminal computer architecture of the time. In 1972, Herman Goldstine, who was unaware of Colossus and its legacy to the projects of people such as Alan Turing (ACE), Max Newman (Manchester computers) and Harry Huskey (Bendix G-15), wrote that,",
"title": "Influence and fate"
},
{
"paragraph_id": 39,
"text": "Britain had such vitality that it could immediately after the war embark on so many well-conceived and well-executed projects in the computer field.",
"title": "Influence and fate"
},
{
"paragraph_id": 40,
"text": "Professor Brian Randell, who unearthed information about Colossus in the 1970s, commented on this, saying that:",
"title": "Influence and fate"
},
{
"paragraph_id": 41,
"text": "It is my opinion that the COLOSSUS project was an important source of this vitality, one that has been largely unappreciated, as has the significance of its places in the chronology of the invention of the digital computer.",
"title": "Influence and fate"
},
{
"paragraph_id": 42,
"text": "Randell's efforts started to bear fruit in the mid-1970s. The secrecy about Bletchley Park had been broken when Group Captain Winterbotham published his book The Ultra Secret in 1974. Randell was researching the history of computer science in Britain for a conference on the history of computing held at the Los Alamos Scientific Laboratory, New Mexico on 10-15 June 1976, and got permission to present a paper on wartime development of the COLOSSI at the Post Office Research Station, Dollis Hill (in October 1975 the British Government had released a series of captioned photographs from the Public Record Office). The interest in the “revelations” in his paper resulted in a special evening meeting when Randell and Coombs answered further questions. Coombs later wrote that no member of our team could ever forget the fellowship, the sense of purpose and, above all, the breathless excitement of those days. In 1977 Randell published an article The First Electronic Computer in several journals.",
"title": "Influence and fate"
},
{
"paragraph_id": 43,
"text": "In October 2000, a 500-page technical report on the Tunny cipher and its cryptanalysis—entitled General Report on Tunny—was released by GCHQ to the national Public Record Office, and it contains a fascinating paean to Colossus by the cryptographers who worked with it:",
"title": "Influence and fate"
},
{
"paragraph_id": 44,
"text": "It is regretted that it is not possible to give an adequate idea of the fascination of a Colossus at work; its sheer bulk and apparent complexity; the fantastic speed of thin paper tape round the glittering pulleys; the childish pleasure of not-not, span, print main header and other gadgets; the wizardry of purely mechanical decoding letter by letter (one novice thought she was being hoaxed); the uncanny action of the typewriter in printing the correct scores without and beyond human aid; the stepping of the display; periods of eager expectation culminating in the sudden appearance of the longed-for score; and the strange rhythms characterizing every type of run: the stately break-in, the erratic short run, the regularity of wheel-breaking, the stolid rectangle interrupted by the wild leaps of the carriage-return, the frantic chatter of a motor run, even the ludicrous frenzy of hosts of bogus scores.",
"title": "Influence and fate"
},
{
"paragraph_id": 45,
"text": "Construction of a fully functional rebuild of a Colossus Mark 2 was undertaken between 1993 and 2008 by a team led by Tony Sale. In spite of the blueprints and hardware being destroyed, a surprising amount of material survived, mainly in engineers' notebooks, but a considerable amount of it in the U.S. The optical tape reader might have posed the biggest problem, but Dr. Arnold Lynch, its original designer was able to redesign it to his own original specification. The reconstruction is on display, in the historically correct place for Colossus No. 9, at The National Museum of Computing, in H Block Bletchley Park in Milton Keynes, Buckinghamshire.",
"title": "Reconstruction"
},
{
"paragraph_id": 46,
"text": "In November 2007, to celebrate the project completion and to mark the start of a fundraising initiative for The National Museum of Computing, a Cipher Challenge pitted the rebuilt Colossus against radio amateurs worldwide in being first to receive and decode three messages enciphered using the Lorenz SZ42 and transmitted from radio station DL0HNF in the Heinz Nixdorf MuseumsForum computer museum. The challenge was easily won by radio amateur Joachim Schüth, who had carefully prepared for the event and developed his own signal processing and code-breaking code using Ada. The Colossus team were hampered by their wish to use World War II radio equipment, delaying them by a day because of poor reception conditions. Nevertheless, the victor's 1.4 GHz laptop, running his own code, took less than a minute to find the settings for all 12 wheels. The German codebreaker said: \"My laptop digested ciphertext at a speed of 1.2 million characters per second—240 times faster than Colossus. If you scale the CPU frequency by that factor, you get an equivalent clock of 5.8 MHz for Colossus. That is a remarkable speed for a computer built in 1944.\"",
"title": "Reconstruction"
},
{
"paragraph_id": 47,
"text": "The Cipher Challenge verified the successful completion of the rebuild project. \"On the strength of today's performance Colossus is as good as it was six decades ago\", commented Tony Sale. \"We are delighted to have produced a fitting tribute to the people who worked at Bletchley Park and whose brainpower devised these fantastic machines which broke these ciphers and shortened the war by many months.\"",
"title": "Reconstruction"
},
{
"paragraph_id": 48,
"text": "There was a fictional computer named Colossus in the 1970 film Colossus: The Forbin Project which was based on the 1966 novel Colossus by D. F. Jones. This was a coincidence as it pre-dates the public release of information about Colossus, or even its name.",
"title": "Other meanings"
},
{
"paragraph_id": 49,
"text": "Neal Stephenson's novel Cryptonomicon (1999) also contains a fictional treatment of the historical role played by Turing and Bletchley Park.",
"title": "Other meanings"
}
] | Colossus was a set of computers developed by British codebreakers in the years 1943–1945 to help in the cryptanalysis of the Lorenz cipher. Colossus used thermionic valves to perform Boolean and counting operations. Colossus is thus regarded as the world's first programmable, electronic, digital computer, although it was programmed by switches and plugs and not by a stored program. Colossus was designed by General Post Office (GPO) research telephone engineer Tommy Flowers to solve a problem posed by mathematician Max Newman at the Government Code and Cypher School (GC&CS) at Bletchley Park. Alan Turing's use of probability in cryptanalysis contributed to its design. It has sometimes been erroneously stated that Turing designed Colossus to aid the cryptanalysis of the Enigma. The prototype, Colossus Mark 1, was shown to be working in December 1943 and was in use at Bletchley Park by early 1944. An improved Colossus Mark 2 that used shift registers to quintuple the processing speed, first worked on 1 June 1944, just in time for the Normandy landings on D-Day. Ten Colossi were in use by the end of the war and an eleventh was being commissioned. Bletchley Park's use of these machines allowed the Allies to obtain a vast amount of high-level military intelligence from intercepted radiotelegraphy messages between the German High Command (OKW) and their army commands throughout occupied Europe. The existence of the Colossus machines was kept secret until the mid-1970s. All but two machines were dismantled into such small parts that their use could not be inferred. The two retained machines were eventually dismantled in the 1960s. A functioning rebuild of a Mark 2 Colossus was completed in 2008 by Tony Sale and a team of volunteers; it is on display at The National Museum of Computing on Bletchley Park. | 2001-09-06T16:48:11Z | 2023-11-23T09:13:23Z | [
"Template:Convert",
"Template:Quote",
"Template:Reflist",
"Template:Citation",
"Template:Refend",
"Template:YouTube",
"Template:Commons category",
"Template:Efn",
"Template:Cbignore",
"Template:Cite journal",
"Template:Short description",
"Template:Notelist",
"Template:Cite web",
"Template:Cite news",
"Template:Mainframes",
"Template:Use dmy dates",
"Template:Cite AV media",
"Template:Harvp",
"Template:Infobox information appliance",
"Template:Frac",
"Template:Cite conference",
"Template:Citation needed",
"Template:Refbegin",
"Template:Sfn",
"Template:See also",
"Template:Cn",
"Template:Blockquote",
"Template:Cite book",
"Template:Distinguish"
] | https://en.wikipedia.org/wiki/Colossus_computer |
6,230 | Canadian Shield | The Canadian Shield (French: Bouclier canadien [buklje kanadjɛ̃]), also called the Laurentian Plateau, is a geologic shield, a large area of exposed Precambrian igneous and high-grade metamorphic rocks. It forms the North American Craton (or Laurentia), the ancient geologic core of the North American continent. Glaciation has left the area with only a thin layer of soil, through which exposures of igneous bedrock resulting from its long volcanic history are frequently visible. As a deep, common, joined bedrock region in eastern and central Canada, the Shield stretches north from the Great Lakes to the Arctic Ocean, covering over half of Canada and most of Greenland; it also extends south into the northern reaches of the United States.
The Canadian Shield is a physiographic division comprising four smaller physiographic provinces: the Laurentian Upland, Kazan Region, Davis and James. The shield extends into the United States as the Adirondack Mountains (connected by the Frontenac Axis) and the Superior Upland. The Canadian Shield is a U-shaped subsection of the Laurentia craton signifying the area of greatest glacial impact (scraping down to bare rock) creating the thin soils. The age of the Canadian Shield is estimated to be 4.28 Ga. The Canadian Shield once had jagged peaks, higher than any of today's mountains, but millions of years of erosion have changed these mountains to rolling hills.
The Canadian Shield is a collage of Archean plates and accreted juvenile arc terranes and sedimentary basins of the Proterozoic Eon that were progressively amalgamated during the interval 2.45–1.24 Ga, with the most substantial growth period occurring during the Trans-Hudson orogeny, between c. 1.90–1.80 Ga. The Canadian Shield was the first part of North America to be permanently elevated above sea level and has remained almost wholly untouched by successive encroachments of the sea upon the continent. It is the Earth's greatest area of exposed Archean rock. The metamorphic base rocks are mostly from the Precambrian (between 4.5 billion and 540 million years ago) and have been repeatedly uplifted and eroded. Today it consists largely of an area of low relief 300–610 m (980–2,000 ft) above sea level with a few monadnocks and low mountain ranges (including the Laurentian Mountains) probably eroded from the plateau during the Cenozoic Era. During the Pleistocene Epoch, continental ice sheets depressed the land surface (creating Hudson Bay) but also tilted up its northeastern "rim" (the Torngat), scooped out thousands of lake basins, and carried away much of the region's soil. The northeastern portion, however, became tilted up so that, in northern Labrador and Baffin Island, the land rises to more than 1,500 metres (5,000 feet) above sea level.
When the Greenland section is included, the Canadian Shield is approximately circular, bounded on the northeast by the northeast edge of Greenland, with Hudson Bay in the middle. It covers much of Greenland, all of Labrador and the Great Northern Peninsula of Newfoundland, most of Quebec north of the St. Lawrence River, much of Ontario including northern sections of the Ontario Peninsula, the Adirondack Mountains of New York, the northernmost part of Lower Michigan and all of Upper Michigan, northern Wisconsin, northeastern Minnesota, the central and northern portions of Manitoba away from Hudson Bay, northern Saskatchewan, a small portion of northeastern Alberta, mainland Northwest Territories to the east of a line extended north from the Saskatchewan-Alberta border, most of Nunavut's mainland and, of its Arctic Archipelago, Baffin Island and significant bands through Somerset, Southampton, Devon and Ellesmere islands. In total, the exposed area of the Shield covers approximately 8,000,000 km (3,100,000 sq mi). The true extent of the Shield is greater still and stretches from the Western Cordillera in the west to the Appalachians in the east and as far south as Texas, but these regions are overlaid with much younger rocks and sediment.
The Canadian Shield is among the oldest on Earth, with regions dating from 2.5 to 4.2 billion years. The multitude of rivers and lakes in the region is classical example of a deranged drainage system, caused by the watersheds of the area being disturbed by glaciation and the effect of post-glacial rebound. The Shield was originally an area of very large, very tall mountains (about 12,000 m or 39,000 ft) with much volcanic activity, but the area was eroded to nearly its current topographic appearance of relatively low relief over 500 million years ago. Erosion has exposed the roots of the mountains, which take the form of greenstone belts in which belts of volcanic rock that have been altered by metamorphism are surrounded by granitic rock. These belts range in age from 3600 to 2680 million years old. Much of the granitic rock belongs to the distinctive tonalite–trondhjemite–granodiorite family of rocks, which are characteristic of Archean continental crust. Many of Canada's major ore deposits are associated with greenstone belts.
The Sturgeon Lake Caldera in Kenora District, Ontario, is one of the world's best preserved mineralized Neoarchean caldera complexes, which is 2.7 billion years old. The Canadian Shield also contains the Mackenzie dike swarm, which is the largest dike swarm known on Earth.
Mountains have deep roots and float on the denser mantle much like an iceberg at sea. As mountains erode, their roots rise and are eroded in turn. The rocks that now form the surface of the Shield were once far below the Earth's surface.
The high pressures and temperatures at those depths provided ideal conditions for mineralization. Although these mountains are now heavily eroded, many large mountains still exist in Canada's far north called the Arctic Cordillera. This is a vast, deeply dissected mountain range, stretching from northernmost Ellesmere Island to the northernmost tip of Labrador. The range's highest peak is Nunavut's Barbeau Peak at 2,616 metres (8,583 ft) above sea level. Precambrian rock is the major component of the bedrock.
The North American craton is the bedrock forming the heart of the North American continent and the Canadian Shield is the largest exposed part of the craton's bedrock.
The Canadian Shield is part of an ancient continent called Arctica, which was formed about 2.5 billion years ago during the Neoarchean era. It was split into Greenland, Laurentia, Scotland, and Siberia, and is now roughly situated in the Arctic around the current North Pole.
The current surface expression of the Shield is one of very thin soil lying on top of the bedrock, with many bare outcrops. This arrangement was caused by severe glaciation during the ice age, which covered the Shield and scraped the rock clean.
The lowlands of the Canadian Shield have a very dense soil that is not suitable for forestation; it also contains many marshes and bogs (muskegs). The rest of the region has coarse soil that does not retain moisture well and is frozen with permafrost throughout the year. Forests are not as dense in the north.
The Shield is covered in parts by vast boreal forests in the south that support natural ecosystems as well as a major logging industry. The boreal forest area gives way to the Eastern Canadian Shield taiga that covers northern Quebec and most of Labrador. The Midwestern Canadian Shield forests that run westwards from Northwestern Ontario have boreal forests that give way to taiga in the most northerly parts of Manitoba and Saskatchewan. Hydrologic drainage is generally poor, the soil compacting effects of glaciation being one of the many causes. Tundra typically prevails in the northern regions. Many mammals such as caribou, white-tailed deer, moose, wolves, wolverines, weasels, mink, otters, grizzly bear, polar bears and black bears are present. In the case of polar bears (Ursus maritimus), the Shield area contains many of their denning locations, such as the Wapusk National Park. The many lakes and rivers on the Shield contain a plentiful quantity of different sports fish species, including walleye, northern pike, lake trout, yellow perch, whitefish, brook trout, arctic grayling, and many types of baitfish. The water surfaces are also home to many waterfowl, most notably Canada geese, loons and gulls. The vast forests contain a myriad population of other birds, including ravens and crows, predatory birds and many songbirds.
The Canadian Shield is one of the world's richest areas in terms of mineral ores. It is filled with substantial deposits of nickel, gold, silver, and copper. Throughout the Shield there are many mining towns extracting these minerals. The largest, and one of the best known, is Sudbury, Ontario. Sudbury is an exception to the normal process of forming minerals in the Shield since the Sudbury Basin is an ancient meteorite impact crater. Ejecta from the meteorite impact was found in the Rove Formation in May 2007. The nearby but less-known Temagami Magnetic Anomaly has striking similarities to the Sudbury Basin. This suggests it could be a second metal-rich impact crater.
In northeastern Quebec, the giant Manicouagan Reservoir is the site of an extensive hydroelectric project (Manic-cinq, or Manic-5). This is one of the largest-known meteorite impact craters on Earth, though not as large as the Sudbury crater; it is currently ranked 5th, while Sudbury is 3rd.
The Flin Flon greenstone belt in central Manitoba and east-central Saskatchewan "is one of the largest Paleoproterozoic volcanic-hosted massive sulfide (VMS) districts in the world, containing 27 copper-zinc-(gold) deposits from which more than 183 million tonnes of sulfide have been mined."
The Canadian Shield, particularly the portion in the Northwest Territories, has recently been the site of several major diamond discoveries. The kimberlite pipes in which the diamonds are found are closely associated with cratons, which provide the deep lithospheric mantle required to stabilize diamond as a mineral. The kimberlite eruptions then bring the diamonds from over 150 kilometres (93 mi) depth to the surface. The Ekati and Diavik mines are actively mining kimberlite diamonds. | [
{
"paragraph_id": 0,
"text": "The Canadian Shield (French: Bouclier canadien [buklje kanadjɛ̃]), also called the Laurentian Plateau, is a geologic shield, a large area of exposed Precambrian igneous and high-grade metamorphic rocks. It forms the North American Craton (or Laurentia), the ancient geologic core of the North American continent. Glaciation has left the area with only a thin layer of soil, through which exposures of igneous bedrock resulting from its long volcanic history are frequently visible. As a deep, common, joined bedrock region in eastern and central Canada, the Shield stretches north from the Great Lakes to the Arctic Ocean, covering over half of Canada and most of Greenland; it also extends south into the northern reaches of the United States.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The Canadian Shield is a physiographic division comprising four smaller physiographic provinces: the Laurentian Upland, Kazan Region, Davis and James. The shield extends into the United States as the Adirondack Mountains (connected by the Frontenac Axis) and the Superior Upland. The Canadian Shield is a U-shaped subsection of the Laurentia craton signifying the area of greatest glacial impact (scraping down to bare rock) creating the thin soils. The age of the Canadian Shield is estimated to be 4.28 Ga. The Canadian Shield once had jagged peaks, higher than any of today's mountains, but millions of years of erosion have changed these mountains to rolling hills.",
"title": "Geographical extent"
},
{
"paragraph_id": 2,
"text": "The Canadian Shield is a collage of Archean plates and accreted juvenile arc terranes and sedimentary basins of the Proterozoic Eon that were progressively amalgamated during the interval 2.45–1.24 Ga, with the most substantial growth period occurring during the Trans-Hudson orogeny, between c. 1.90–1.80 Ga. The Canadian Shield was the first part of North America to be permanently elevated above sea level and has remained almost wholly untouched by successive encroachments of the sea upon the continent. It is the Earth's greatest area of exposed Archean rock. The metamorphic base rocks are mostly from the Precambrian (between 4.5 billion and 540 million years ago) and have been repeatedly uplifted and eroded. Today it consists largely of an area of low relief 300–610 m (980–2,000 ft) above sea level with a few monadnocks and low mountain ranges (including the Laurentian Mountains) probably eroded from the plateau during the Cenozoic Era. During the Pleistocene Epoch, continental ice sheets depressed the land surface (creating Hudson Bay) but also tilted up its northeastern \"rim\" (the Torngat), scooped out thousands of lake basins, and carried away much of the region's soil. The northeastern portion, however, became tilted up so that, in northern Labrador and Baffin Island, the land rises to more than 1,500 metres (5,000 feet) above sea level.",
"title": "Geographical extent"
},
{
"paragraph_id": 3,
"text": "When the Greenland section is included, the Canadian Shield is approximately circular, bounded on the northeast by the northeast edge of Greenland, with Hudson Bay in the middle. It covers much of Greenland, all of Labrador and the Great Northern Peninsula of Newfoundland, most of Quebec north of the St. Lawrence River, much of Ontario including northern sections of the Ontario Peninsula, the Adirondack Mountains of New York, the northernmost part of Lower Michigan and all of Upper Michigan, northern Wisconsin, northeastern Minnesota, the central and northern portions of Manitoba away from Hudson Bay, northern Saskatchewan, a small portion of northeastern Alberta, mainland Northwest Territories to the east of a line extended north from the Saskatchewan-Alberta border, most of Nunavut's mainland and, of its Arctic Archipelago, Baffin Island and significant bands through Somerset, Southampton, Devon and Ellesmere islands. In total, the exposed area of the Shield covers approximately 8,000,000 km (3,100,000 sq mi). The true extent of the Shield is greater still and stretches from the Western Cordillera in the west to the Appalachians in the east and as far south as Texas, but these regions are overlaid with much younger rocks and sediment.",
"title": "Geographical extent"
},
{
"paragraph_id": 4,
"text": "The Canadian Shield is among the oldest on Earth, with regions dating from 2.5 to 4.2 billion years. The multitude of rivers and lakes in the region is classical example of a deranged drainage system, caused by the watersheds of the area being disturbed by glaciation and the effect of post-glacial rebound. The Shield was originally an area of very large, very tall mountains (about 12,000 m or 39,000 ft) with much volcanic activity, but the area was eroded to nearly its current topographic appearance of relatively low relief over 500 million years ago. Erosion has exposed the roots of the mountains, which take the form of greenstone belts in which belts of volcanic rock that have been altered by metamorphism are surrounded by granitic rock. These belts range in age from 3600 to 2680 million years old. Much of the granitic rock belongs to the distinctive tonalite–trondhjemite–granodiorite family of rocks, which are characteristic of Archean continental crust. Many of Canada's major ore deposits are associated with greenstone belts.",
"title": "Geology"
},
{
"paragraph_id": 5,
"text": "The Sturgeon Lake Caldera in Kenora District, Ontario, is one of the world's best preserved mineralized Neoarchean caldera complexes, which is 2.7 billion years old. The Canadian Shield also contains the Mackenzie dike swarm, which is the largest dike swarm known on Earth.",
"title": "Geology"
},
{
"paragraph_id": 6,
"text": "Mountains have deep roots and float on the denser mantle much like an iceberg at sea. As mountains erode, their roots rise and are eroded in turn. The rocks that now form the surface of the Shield were once far below the Earth's surface.",
"title": "Geology"
},
{
"paragraph_id": 7,
"text": "The high pressures and temperatures at those depths provided ideal conditions for mineralization. Although these mountains are now heavily eroded, many large mountains still exist in Canada's far north called the Arctic Cordillera. This is a vast, deeply dissected mountain range, stretching from northernmost Ellesmere Island to the northernmost tip of Labrador. The range's highest peak is Nunavut's Barbeau Peak at 2,616 metres (8,583 ft) above sea level. Precambrian rock is the major component of the bedrock.",
"title": "Geology"
},
{
"paragraph_id": 8,
"text": "The North American craton is the bedrock forming the heart of the North American continent and the Canadian Shield is the largest exposed part of the craton's bedrock.",
"title": "Geology"
},
{
"paragraph_id": 9,
"text": "The Canadian Shield is part of an ancient continent called Arctica, which was formed about 2.5 billion years ago during the Neoarchean era. It was split into Greenland, Laurentia, Scotland, and Siberia, and is now roughly situated in the Arctic around the current North Pole.",
"title": "Geology"
},
{
"paragraph_id": 10,
"text": "The current surface expression of the Shield is one of very thin soil lying on top of the bedrock, with many bare outcrops. This arrangement was caused by severe glaciation during the ice age, which covered the Shield and scraped the rock clean.",
"title": "Ecology"
},
{
"paragraph_id": 11,
"text": "The lowlands of the Canadian Shield have a very dense soil that is not suitable for forestation; it also contains many marshes and bogs (muskegs). The rest of the region has coarse soil that does not retain moisture well and is frozen with permafrost throughout the year. Forests are not as dense in the north.",
"title": "Ecology"
},
{
"paragraph_id": 12,
"text": "The Shield is covered in parts by vast boreal forests in the south that support natural ecosystems as well as a major logging industry. The boreal forest area gives way to the Eastern Canadian Shield taiga that covers northern Quebec and most of Labrador. The Midwestern Canadian Shield forests that run westwards from Northwestern Ontario have boreal forests that give way to taiga in the most northerly parts of Manitoba and Saskatchewan. Hydrologic drainage is generally poor, the soil compacting effects of glaciation being one of the many causes. Tundra typically prevails in the northern regions. Many mammals such as caribou, white-tailed deer, moose, wolves, wolverines, weasels, mink, otters, grizzly bear, polar bears and black bears are present. In the case of polar bears (Ursus maritimus), the Shield area contains many of their denning locations, such as the Wapusk National Park. The many lakes and rivers on the Shield contain a plentiful quantity of different sports fish species, including walleye, northern pike, lake trout, yellow perch, whitefish, brook trout, arctic grayling, and many types of baitfish. The water surfaces are also home to many waterfowl, most notably Canada geese, loons and gulls. The vast forests contain a myriad population of other birds, including ravens and crows, predatory birds and many songbirds.",
"title": "Ecology"
},
{
"paragraph_id": 13,
"text": "The Canadian Shield is one of the world's richest areas in terms of mineral ores. It is filled with substantial deposits of nickel, gold, silver, and copper. Throughout the Shield there are many mining towns extracting these minerals. The largest, and one of the best known, is Sudbury, Ontario. Sudbury is an exception to the normal process of forming minerals in the Shield since the Sudbury Basin is an ancient meteorite impact crater. Ejecta from the meteorite impact was found in the Rove Formation in May 2007. The nearby but less-known Temagami Magnetic Anomaly has striking similarities to the Sudbury Basin. This suggests it could be a second metal-rich impact crater.",
"title": "Mining and economics"
},
{
"paragraph_id": 14,
"text": "In northeastern Quebec, the giant Manicouagan Reservoir is the site of an extensive hydroelectric project (Manic-cinq, or Manic-5). This is one of the largest-known meteorite impact craters on Earth, though not as large as the Sudbury crater; it is currently ranked 5th, while Sudbury is 3rd.",
"title": "Mining and economics"
},
{
"paragraph_id": 15,
"text": "The Flin Flon greenstone belt in central Manitoba and east-central Saskatchewan \"is one of the largest Paleoproterozoic volcanic-hosted massive sulfide (VMS) districts in the world, containing 27 copper-zinc-(gold) deposits from which more than 183 million tonnes of sulfide have been mined.\"",
"title": "Mining and economics"
},
{
"paragraph_id": 16,
"text": "The Canadian Shield, particularly the portion in the Northwest Territories, has recently been the site of several major diamond discoveries. The kimberlite pipes in which the diamonds are found are closely associated with cratons, which provide the deep lithospheric mantle required to stabilize diamond as a mineral. The kimberlite eruptions then bring the diamonds from over 150 kilometres (93 mi) depth to the surface. The Ekati and Diavik mines are actively mining kimberlite diamonds.",
"title": "Mining and economics"
}
] | The Canadian Shield, also called the Laurentian Plateau, is a geologic shield, a large area of exposed Precambrian igneous and high-grade metamorphic rocks. It forms the North American Craton, the ancient geologic core of the North American continent. Glaciation has left the area with only a thin layer of soil, through which exposures of igneous bedrock resulting from its long volcanic history are frequently visible. As a deep, common, joined bedrock region in eastern and central Canada, the Shield stretches north from the Great Lakes to the Arctic Ocean, covering over half of Canada and most of Greenland; it also extends south into the northern reaches of the United States. | 2001-08-30T19:28:44Z | 2023-11-26T07:39:53Z | [
"Template:Cite bivouac",
"Template:Physiographic regions",
"Template:Wide image",
"Template:Lang",
"Template:Portal",
"Template:Cite encyclopedia",
"Template:Cite book",
"Template:Infobox rockunit",
"Template:Clarify",
"Template:Cite web",
"Template:Webarchive",
"Template:Authority control",
"Template:IPA-fr",
"Template:Convert",
"Template:Reflist",
"Template:Cite journal",
"Template:NatGeo ecoregion",
"Template:Canada topics",
"Template:Continental Glaciations",
"Template:Short description",
"Template:Lang-fr",
"Template:When",
"Template:Library resources box",
"Template:ISBN"
] | https://en.wikipedia.org/wiki/Canadian_Shield |
6,231 | Comic book | A comic book, also called comicbook, comic magazine or simply comic, is a publication that consists of comics art in the form of sequential juxtaposed panels that represent individual scenes. Panels are often accompanied by descriptive prose and written narrative, usually, dialogue contained in word balloons emblematic of the comics art form.
"Comic Cuts" was a British comic published from 1890 to 1953. It was preceded by "Ally Sloper's Half Holiday" (1884) which is notable for its use of sequential cartoons to unfold narrative. These British comics existed alongside the popular lurid "Penny dreadfuls" (such as "Spring-heeled Jack"), boys' "Story papers" and the humorous Punch (magazine) which was the first to use the term "cartoon" in its modern sense of a humorous drawing. The interweaving of drawings and the written word had been pioneered by, among others, William Blake (1757 - 1857) in works such as Blake's "The Descent Of Christ" (1804 - 1820).
The first modern (American style) comic book, Famous Funnies, was released in the US in 1934 and was a reprinting of earlier newspaper humor comic strips, which had established many of the story-telling devices used in comics. The term comic book derives from American comic books once being a compilation of comic strips of a humorous tone; however, this practice was replaced by featuring stories of all genres, usually not humorous in tone.
The largest comic book market is Japan. By 1995, the manga market in Japan was valued at ¥586.4 billion ($6–7 billion), with annual sales of 1.9 billion manga books (tankōbon volumes and manga magazines) in Japan, equivalent to 15 issues per person. In 2020 the manga market in Japan reached a new record value of ¥612.5 billion due to a fast growth of digital manga sales as well as an increase in print sales. The comic book market in the United States and Canada was valued at $1.09 billion in 2016. As of 2017, the largest comic book publisher in the United States is manga distributor Viz Media, followed by DC Comics and Marvel Comics the original feature full length special edition franchises including Superman, Batman, Wonder Woman, Spider-Man, the Incredible Hulk and the X-Men. The best-selling comic book categories in the US as of 2019 are juvenile children's fiction at 41%, manga at 28% and superhero comics at 10% of the market. Another major comic book market is France, where Franco-Belgian comics and Japanese manga each represent 40% of the market, followed by American comics at 10% market share.
Comic books heavily rely on their organization and visual presentation. Authors dedicate significant attention to aspects like page layout, size, orientation, and the positioning of panels. These characteristics are crucial for effectively conveying the content and messages within the comic book. Key components of comic books encompass panels, speech bubbles (also known as balloons), text lines, and characters. Speech balloons generally take the form of convex containers that hold character dialogue and are connected to the character via a tail element. The tail comprises an origin, path, tip, and directional point. The creation of comic books involves several essential steps: writing, drawing, and coloring. Various technological tools and methods are employed to craft comic books, incorporating concepts such as directions, axes, data, and metrics. Following these formatting guidelines, the process unfolds with writing, drawing, and coloring. In the United States, the term "comic book", is generally used for comics periodicals and trade paperbacks while "graphic novel" is the term used for standalone books.
Comics as a print medium have existed in the United States since the printing of The Adventures of Mr. Obadiah Oldbuck in 1842 in hardcover, making it the first known American prototype comic book. Proto-comics periodicals began appearing early in the 20th century, with the first comic standard-sized comic being Funnies on Parade. Funnies on Parades was the first book that established the size, duration, and format of the modern comic book. Following this was, Dell Publishing's 36-page Famous Funnies: A Carnival of Comics as the first true newsstand American comic book; Goulart, for example, calls it "the cornerstone for one of the most lucrative branches of magazine publishing". In 1905 G.W. Dillingham Company published 24 select strips by the cartoonist Gustave Verbeek in an anthology book called 'The Incredible Upside-Downs of Little Lady Lovekins and Old Man Muffaroo'. The introduction of Jerry Siegel and Joe Shuster's Superman in 1938 turned comic books into a major industry and ushered in the Golden Age of Comic Books. The Golden Age originated the archetype of the superhero. According to historian Michael A. Amundson, appealing comic-book characters helped ease young readers' fear of nuclear war and neutralize anxiety about the questions posed by atomic power.
Historians generally divide the timeline of the American comic book into eras. The Golden Age of Comic Books began in 1938, with the debut of Superman in Action Comics #1, published by Detective Comics (predecessor of DC Comics), which is generally considered the beginning of the modern comic book as it is known today. The Silver Age of Comic Books is generally considered to date from the first successful revival of the then-dormant superhero form, with the debut of the Flash in Showcase #4 (Oct. 1956). The Silver Age lasted through the late 1960s or early 1970s, during which time Marvel Comics revolutionized the medium with such naturalistic superheroes as Stan Lee and Jack Kirby's Fantastic Four and Lee and Steve Ditko's Spider-Man. The demarcation between the Silver Age and the following era, the Bronze Age of Comic Books, is less well-defined, with the Bronze Age running from the very early 1970s through the mid-1980s. The Modern Age of Comic Books runs from the mid-1980s to the present day.
A significant event in the timeline of American comic books occurred when psychiatrist Fredric Wertham voiced his criticisms of the medium through his book Seduction of the Innocent (1954). This critique led to the involvement of the American Senate Subcommittee on Juvenile Delinquency, which launched an investigation into comic books. Wertham argued that comic books were accountable for a surge in juvenile delinquency and posed a potential impact on a child's sexuality and moral values. In response to attention from the government and from the media, the US comic book industry set up the Comics Magazine Association of America. The CMAA instilled the Comics Code Authority in 1954 and drafted the self-censorship Comics Code that year, which required all comic books to go through a process of approval. It was not until the 1970s that comic books could be published without passing through the inspection of the CMAA. The Code was made formally defunct in November 2011.
In the late 1960s and early 1970s, a surge of creativity emerged in what became known as underground comics. Published and distributed independently of the established comics industry, most of such comics reflected the youth counterculture and drug culture of the time. Underground comix "reflected and commented on the social divisions and tensions of American society". Many had an uninhibited, often irreverent style; their frank depictions of nudity, sex, profanity, and politics had no parallel outside their precursors, the pornographic and even more obscure "Tijuana bibles". Underground comics were almost never sold at newsstands, but rather in such youth-oriented outlets as head shops and record stores, as well as by mail order. The underground comics encouraged creators to publish their work independently so that they would have full ownership rights to their characters.
Frank Stack's The Adventures of Jesus, published under the name Foolbert Sturgeon, has been credited as the first underground comic; while R. Crumb and the crew of cartoonists who worked on Zap Comix popularized the form.
The rise of comic book specialty stores in the late 1970s created and paralleled a dedicated market for "independent" or "alternative comics" in the US. The first such comics included the anthology series Star Reach, published by comic book writer Mike Friedrich from 1974 to 1979, and Harvey Pekar's American Splendor, which continued sporadic publication into the 21st century and which Shari Springer Berman and Robert Pulcini adapted into a 2003 film. Some independent comics continued in the tradition of underground comics. While their content generally remained less explicit, others resembled the output of mainstream publishers in format and genre but were published by smaller artist-owned companies or by single artists. A few (notably RAW) represented experimental attempts to bring comics closer to the status of fine art.
During the 1970s the "small press" culture grew and diversified. By the 1980s, several independent publishers – such as Pacific, Eclipse, First, Comico, and Fantagraphics – had started releasing a wide range of styles and formats—from color-superhero, detective, and science-fiction comic books to black-and-white magazine-format stories of Latin American magical realism.
A number of small publishers in the 1990s, changed the format and distribution of their comics to more closely resemble non-comics publishing. The "minicomics" form, an extremely informal version of self-publishing, arose in the 1980s and became increasingly popular among artists in the 1990s, despite reaching an even more limited audience than the small press.
Small publishers regularly releasing titles include Avatar Press, Hyperwerks, Raytoons, and Terminal Press, buoyed by such advances in printing technology as digital print-on-demand.
In 1964, Richard Kyle coined the term "graphic novel".
Precursors of the form existed by the 1920s, which saw a revival of the medieval woodcut tradition by Belgian Frans Masereel, American Lynd Ward and others, including Stan Lee.
In 1947, Fawcett Publications published "Comics Novel No. 1", as the first in an intended series of these "comics novels". The story in the first issue was "Anarcho, Dictator of Death", a five chapter spy genre tale written by Otto Binder and drawn by Al Carreno. It is readable online in the Digital Comic Museum. The magazine never reached a second issue.
In 1950, St. John Publications produced the digest-sized, adult-oriented "picture novel" It Rhymes with Lust, a 128-page digest by pseudonymous writer "Drake Waller" (Arnold Drake and Leslie Waller), penciler Matt Baker and inker Ray Osrin, touted as "an original full-length novel" on its cover. "It Rhymes with Lust" is also available to read online in the Digital Comic Museum.
In 1971, writer-artist Gil Kane and collaborators applied a paperback format to their "comics novel" Blackmark. Will Eisner popularized the term "graphic novel" when he used it on the cover of the paperback edition of his work A Contract with God, and Other Tenement Stories in 1978 and, subsequently, the usage of the term began to increase.
In 2017, the comic book market size for North America was just over $1 billion with digital sales being flat, book stores having a 1 percent decline, and comic book stores having a 10 percent decline over 2016. The global comic book market saw a substantial 12% growth in 2020, reaching a total worth of USD 8.49 billion. This positive trajectory continued in 2021, with the market's annual valuation surging to USD 9.21 billion. The rising popularity of comic books can be attributed to heightened global interest, driven significantly by collaborative efforts among diverse brands. These collaborations are geared towards producing more engaging and appealing comic content, contributing to the industry's continued growth.
The 1970s saw the advent of specialty comic book stores. Initially, comic books were marketed by publishers to children because comic books were perceived as children's entertainment. However, with increasing recognition of comics as an art form and the growing pop culture presence of comic book conventions, they are now embraced by many adults.
Comic book collectors often exhibit a lifelong passion for the stories within comics, often focusing on specific superheroes and striving to gather a complete collection of a particular series. Comics are assigned sequential numbers, and the initial issue of a long-lasting comic book series tends to be both the scarcest and the most coveted among collectors. The introduction of a new character might occur within an existing title. For instance, the first appearance of Spider-Man took place in Amazing Fantasy #15. New characters were frequently introduced in this manner, waiting for an established audience before launching their own titles. Consequently, comics featuring the debut appearance of a significant character can sometimes be even more challenging to locate than the inaugural issue of that character's standalone series.
Some rare comic books include copies of the unreleased Motion Picture Funnies Weekly #1 from 1939. Eight copies, plus one without a cover, emerged in the estate of the deceased publisher in 1974. The "Pay Copy" of this book sold for $43,125 in a 2005 Heritage auction.
The most valuable American comics have combined rarity and quality with the first appearances of popular and enduring characters. Four comic books have sold for over US$1 million as of December 2010, including two examples of Action Comics #1, the first appearance of Superman, both sold privately through online dealer ComicConnect.com in 2010, and Detective Comics #27, the first appearance of Batman, via public auction.
Updating the above price obtained for Action Comics #1, the first appearance of Superman, the highest sale on record for this book is $3.2 million, for a 9.0 copy.
Misprints, promotional comic-dealer incentive printings, and issues with exceptionally low distribution tend to possess scarcity value in the comic book market. The rarest modern comic books include the original press run of The League of Extraordinary Gentlemen #5, which DC executive Paul Levitz recalled and pulped due to the appearance of a vintage Victorian era advertisement for "Marvel Douche", which the publisher considered offensive; only 100 copies exist, most of which have been CGC graded. (See Recalled comics for more pulped, recalled, and erroneous comics.)
In 2000, a company named Comics Guaranty (CGC) initiated the practice of "slabbing" comics, which involves encasing them within thick plastic cases and assigning them a numerical grade. This approach inspired the emergence of Comic Book Certification Service. Given the significance of condition in determining the value of rare comics, the concept of grading by an impartial company, one that does not engage in buying or selling comics, seemed promising. Nevertheless, there is an ongoing debate regarding whether the relatively high cost of this grading service is justified and whether it serves the interests of collectors or mainly caters to speculators seeking rapid profits, akin to trading in stocks or fine art. Comic grading has played a role in establishing standards for valuation, which online price guides such as GoCollect and GPAnalysis utilize to provide real-time market value information.
Collectors also seek out the original artwork pages from comic books, which are perhaps the most rarefied items in the realm of comic book collecting. These pages hold unparalleled scarcity due to the fact that there exists only one unique page of artwork for every page that was printed and published.
The creation of these original artwork pages involves a collaborative effort: a writer crafts the story, a pencil artist designs the sequential panels on the page, an ink artist goes over the pencil with pen and ink, a letterer provides the dialogue and narration through hand-lettering, and finally, a colorist adds color as the final touch before the pages are sent to the printer.
When the printer returns the original artwork pages, they are typically returned to the artists themselves. These artists sometimes opt to sell these pages at comic book conventions, in galleries, and at art shows centered around comic book art. The original pages from DC and Marvel, featuring the debut appearances of iconic characters such as Superman, Batman, Wonder Woman, the Flash, Captain Marvel, Spider-Man, the Incredible Hulk, Iron Man, Captain America and the Mighty Thor are regarded as priceless treasures within the comic book world.
Many early iterations of black characters in comics "became variations on the 'single stereotypical image of Sambo'." Sambo was closely related to the coon stereotype but had some subtle differences. They are both a derogatory way of portraying black characters. "The name itself, an abbreviation of raccoon, is dehumanizing. As with Sambo, the coon was portrayed as a lazy, easily frightened, chronically idle, inarticulate, buffoon." This portrayal "was of course another attempt to solidify the intellectual inferiority of the black race through popular culture." However, in the 1940s there was a change in portrayal of black characters. "A cursory glance...might give the impression that situations had improved for African Americans in comics." In many comics being produced in this time there was a major push for tolerance between races. "These equality minded heroes began to spring to action just as African Americans were being asked to participate in the war effort."
During this time, a government ran program, the Writers' War Board, became heavily involved in what would be published in comics. "The Writers' War Board used comic books to shape popular perceptions of race and ethnicity..." Not only were they using comic books as a means of recruiting all Americans, they were also using it as propaganda to "[construct] a justification for race-based hatred of America's foreign enemies." The Writers' War Board created comics books that were meant to "[promote] domestic racial harmony". However, "these pro-tolerance narratives struggled to overcome the popular and widely understood negative tropes used for decades in American mass culture...". However, they were not accomplishing this agenda within all of their comics.
In the comic series Captain Marvel Adventures, there was a character named Steamboat who embodied a collection of highly negative stereotypes prevalent during that period. Surprisingly, the Writers' War Board did not request any alterations to this character despite the problematic portrayal. The removal of Steamboat from the series only came about due to the persistent advocacy of a black youth group based in New York City." Originally their request was refused by individuals working on the comic stating, "Captain Marvel Adventures included many kinds of caricatures 'for the sake of humor'." The black youth group responded with "this is not the Negro race, but your one-and-a-half millions readers will think it so." Afterwards, Steamboat disappeared from the comics all together. There was a comic created about the 99th Squadron, also known as the Tuskegee Airmen, an all-black air force unit. Instead of making the comic about their story, the comic was about Hop Harrigan. A white pilot who captures a Nazi, shows him videos of the 99th Squadron defeating his men and then reveals to the Nazi that his men were defeated by African Americans which infuriated him as he sees them as a less superior race and cannot believe they bested his men."The Tuskegee Airmen, and images of black aviators appear in just three of the fifty three panels... the pilots of the 99th Squadron have no dialogue and interact with neither Hop Harrigan nor his Nazi captive." During this time, they also used black characters in comic books as a means to invalidate the militant black groups that were fighting for equality within the U.S. "Spider-Man 'made it clear that militant black power was not the remedy for racial injustice'." "The Falcon openly criticized black behavior stating' maybe it's important fo [sic] us to cool things down-so we can protect the rights we been fightin' for'." This portrayal and character development of black characters can be partially blamed on the fact that, during this time, "there had rarely been a black artist or writer allowed in a major comics company."
Asian characters within comic books encountered similar prejudiced treatment as black characters did. They were subjected to dehumanizing depictions, with narratives often portraying them as "incompetent and subhuman." In a 1944 edition of the publication United States Marines, there was a story titled The Smell of the Monkeymen. This narrative portrayed Japanese soldiers as brutish simians, and it depicted their concealed positions being betrayed by their repugnant body odor. Chinese characters received the same treatment. "By the time the United States entered WWII, negative perceptions of Chinese were an established part of mass culture...." However, concerned that the Japanese could use America's anti-Chinese material as propaganda they began "to present a more positive image of America's Chinese allies..." Just as they tried to show better representation for Black people in comics they did the same for Asian people. However, "Japanese and Filipino characters were visually indistinguishable. Both groups have grotesque buckteeth, tattered clothing, and bright yellow skin." "Publishers depicted America's Asian allies through derogatory images and language honed over the preceding decades." Asian characters were previously portrayed as, "ghastly yellow demons". During WWII, "[every] major superhero worth his spandex devoted himself to the eradication of Asian invaders." There was "a constant relay race in which one Asian culture merely handed off the baton of hatred to another with no perceptible changes in the manner in which the characters would be portrayed."
"The only specific depiction of a Hispanic superhero did not end well. In 1975, Marvel gave us Hector Ayala (a.k.a The White Tiger)." "Although he fought for several years alongside the likes of much more popular heroes such as Spider-Man and Daredevil, he only lasted six years before sales of comics featuring him got so bad that Marvel had him retire. The most famous Hispanic character is Bane, a villain from Batman."
The Native American representation in comic books "can be summed up in the noble savage stereotype" " a recurring theme...urged American indians to abandon their traditional hostility towards the United States. They were the ones painted as intolerant and disrespectful of the dominant concerns of white America".
Manga (漫画) are comic books or graphic novels originating from Japan. Most manga conform to a style developed in Japan in the late 19th century, though the art form has a long prehistory in earlier Japanese art. The term manga is used in Japan to refer to both comics and cartooning in general . Outside Japan, the word is typically used to refer to comics originally published in the country.
Dōjinshi (同人誌, fan magazine), fan-made Japanese comics, operate in a far larger market in Japan than the American "underground comics" market; the largest dōjinshi fair, Comiket, attracts 500,000 visitors twice a year.
Manhwa (만화) are comic books or graphic novels originating from South Korea. The term manhwa is used in South Korea to refer to both comics and cartooning in general. Outside South Korea, the term usually refers to comics originally published in the country. Manhwa is greatly influenced by Japanese Manga comics though it differs from manga and manhua with its own distinct features.
Webtoons have become popular in South Korea as a new way to read comics. Thanks in part to different censorship rules, color and unique visual effects, and optimization for easier reading on smartphones and computers. More manhwa have made the switch from traditional print manhwa to online webtoons thanks to better pay and more freedom than traditional print manhwa. The webtoon format has also expanded to other countries outside of Korea like China, Japan, Southeast Asia, and Western countries. Major webtoon distributors include Lezhin, Naver, and Kakao.
France and Belgium have a long tradition in comics and comic books, often called BDs (an abbreviation of bandes dessinées, meaning literally "drawn strips") in French, and strips in Dutch or Flemish. Belgian comic books originally written in Dutch show the influence of the Francophone "Franco-Belgian" comics but have their own distinct style.
Although Ally Sloper's Half Holiday (1884) was aimed at an adult market, publishers quickly targeted a younger demographic, which has led to most publications being for children and has created an association in the public's mind of comics as somewhat juvenile. The Guardian refers to Ally Sloper as "one of the world's first iconic cartoon characters", and "as famous in Victorian Britain as Dennis the Menace would be a century later." British comics in the early 20th century typically evolved from illustrated penny dreadfuls of the Victorian era (featuring Sweeney Todd, Dick Turpin and Varney the Vampire). First published in the 1830s, penny dreadfuls were "Britain's first taste of mass-produced popular culture for the young."
The two most popular British comic books, The Beano and The Dandy, were first published by DC Thomson in the 1930s. By 1950 the weekly circulation of both reached two million. Explaining the enormous popularity of comics in the UK during this period, Anita O'Brien, director curator at London's Cartoon Museum, states: "When comics like the Beano and Dandy were invented back in the 1930s – and through really to the 1950s and 60s – these comics were almost the only entertainment available to children." Dennis the Menace was created in the 1950s, which saw sales for The Beano soar. He features in the cover of The Beano, with the BBC referring to him as the "definitive naughty boy of the comic world."
In 1954, Tiger comics introduced Roy of the Rovers, the hugely popular football based strip recounting the life of Roy Race and the team he played for, Melchester Rovers. The stock media phrase "real 'Roy of the Rovers' stuff" is often used by football writers, commentators and fans when describing displays of great skill, or surprising results that go against the odds, in reference to the dramatic storylines that were the strip's trademark. Other comic books such as Eagle, Valiant, Warrior, Viz and 2000 AD also flourished. Some comics, such as Judge Dredd and other 2000 AD titles, have been published in a tabloid form. Underground comics and "small press" titles have also appeared in the UK, notably Oz and Escape Magazine.
The content of Action, another title aimed at children and launched in the mid-1970s, became the subject of discussion in the House of Commons. Although on a smaller scale than similar investigations in the US, such concerns led to a moderation of content published within British comics. Such moderation never became formalized to the extent of promulgating a code, nor did it last long. The UK has also established a healthy market in the reprinting and repackaging of material, notably material originating in the US. The lack of reliable supplies of American comic books led to a variety of black-and-white reprints, including Marvel's monster comics of the 1950s, Fawcett's Captain Marvel, and other characters such as Sheena, Mandrake the Magician, and the Phantom. Several reprint companies became involved in repackaging American material for the British market, notably the importer and distributor Thorpe & Porter. Marvel Comics established a UK office in 1972. DC Comics and Dark Horse Comics also opened offices in the 1990s. The repackaging of European material has occurred less frequently, although The Adventures of Tintin and Asterix serials have been successfully translated and repackaged in softcover books. The number of European comics available in the UK has increased in the last two decades. The British company Cinebook, founded in 2005, has released English translated versions of many European series.
In the 1980s, a resurgence of British writers and artists gained prominence in mainstream comic books, which was dubbed the "British Invasion" in comic book history. These writers and artists brought with them their own mature themes and philosophy such as anarchy, controversy and politics common in British media. These elements would pave the way for mature and "darker and edgier" comic books and jump start the Modern Age of Comics. Writers included Alan Moore, famous for his V for Vendetta, From Hell, Watchmen, Marvelman, and The League of Extraordinary Gentlemen; Neil Gaiman with The Sandman mythos and Books of Magic; Warren Ellis, creator of Transmetropolitan and Planetary; and others such as Mark Millar, creator of Wanted and Kick-Ass. The comic book series John Constantine, Hellblazer, which is largely set in Britain and starring the magician John Constantine, paved the way for British writers such as Jamie Delano.
The English musician Peter Gabriel issued in 2000 The Story of OVO which was released in a CD-booklet-shaped comic book as part of the CD edition with the title "OVO The Millennium Show". The 2000 Millennium Dome Show based on it.
At Christmas, publishers repackage and commission material for comic annuals, printed and bound as hardcover A4-size books; "Rupert" supplies a famous example of the British comic annual. DC Thomson also repackages The Broons and Oor Wullie strips in softcover A4-size books for the holiday season.
On 19 March 2012, the British postal service, the Royal Mail, released a set of stamps depicting British comic book characters and series. The collection featured The Beano, The Dandy, Eagle, The Topper, Roy of the Rovers, Bunty, Buster, Valiant, Twinkle and 2000 AD.
It has been stated that the 13th century Cantigas de Santa María could be considered as the first Spanish "comic", although comic books (also known in Spain as historietas or tebeos) made their debut around 1857. The magazine TBO was influential in popularizing the medium. After the Spanish Civil War, the Franco regime imposed strict censorship in all media: superhero comics were forbidden and as a result, comic heroes were based on historical fiction (in 1944 the medieval hero El Guerrero del Antifaz was created by Manuel Gago and another popular medieval hero, Capitán Trueno, was created in 1956 by Víctor Mora and Miguel Ambrosio Zaragoza). Two publishing houses — Editorial Bruguera and Editorial Valenciana — dominated the Spanish comics market during its golden age (1950–1970). The most popular comics showed a recognizable style of slapstick humor (influenced by Franco-Belgian authors such as Franquin): Escobar's Carpanta and Zipi y Zape, Vázquez's Las hermanas Gilda and Anacleto, Ibáñez's Mortadelo y Filemón and 13. Rue del Percebe or Jan's Superlópez. After the end of the Francoist period, there was an increased interest in adult comics with magazines such as Totem, El Jueves, 1984, and El Víbora, and works such as Paracuellos by Carlos Giménez.
Spanish artists have traditionally worked in other markets finding great success, either in the American (e.g., Eisner Award winners Sergio Aragonés, Salvador Larroca, Gabriel Hernández Walta, Marcos Martín or David Aja), the British (e.g., Carlos Ezquerra, co-creator of Judge Dredd) or the Franco-Belgian one (e.g., Fauve d'Or winner Julio Ribera or Blacksad authors Juan Díaz Canales and Juanjo Guarnido).
In Italy, comics (known in Italian as fumetti) made their debut as humor strips at the end of the 19th century, and later evolved into adventure stories. After World War II, however, artists like Hugo Pratt and Guido Crepax exposed Italian comics to an international audience. Popular comic books such as Diabolik or the Bonelli line—namely Tex Willer or Dylan Dog—remain best-sellers.
Mainstream comics are usually published on a monthly basis, in a black-and-white digest size format, with approximately 100 to 132 pages. Collections of classic material for the most famous characters, usually with more than 200 pages, are also common. Author comics are published in the French BD format, with an example being Pratt's Corto Maltese.
Italian cartoonists show the influence of comics from other countries, including France, Belgium, Spain, and Argentina. Italy is also famous for being one of the foremost producers of Walt Disney comic stories outside the US; Donald Duck's superhero alter ego, Paperinik, known in English as Superduck, was created in Italy.
The comic book industry has struggled with distribution issues throughout its history, as numerous mainstream retailers have been hesitant to stock substantial quantities of the most engaging and sought-after comics. The smartphone and the tablet have turned out to be an ideal medium for online distribution.
On 13 November 2007, Marvel Comics launched Marvel Digital Comics Unlimited, a subscription service allowing readers to read many comics from Marvel's history online. The service also includes periodic release new comics not available elsewhere. With the release of Avenging Spider-Man #1, Marvel also became the first publisher to provide free digital copies as part of the print copy of the comic book.
With the growing popularity of smartphones and tablets, many major publishers have begun releasing titles in digital form. The most popular platform is comiXology. Some platforms, such as Graphicly, have shut down.
Numerous libraries house extensive collections of comics in the form of graphic novels. This serves as a convenient means for the general public to become acquainted with the medium.
In 2015, the Japanese manga artist Eiichiro Oda was awarded the Guinness World Records title for having the "Most copies published for the same comic book series by a single author". His manga series One Piece, which he writes and illustrates, has been serialized in the Japanese magazine Weekly Shōnen Jump since December 1997, and by 2015, 77 collected volumes had been released. Guinness World Records reported in their announcement that the collected volumes of the series had sold a total of 320,866,000 units. One Piece also holds the Guinness World Records title for "Most copies published for the same manga series".
On 5 August 2018, the Guinness World Records title for the "Largest comic book ever published" was awarded to the Brazilian comic book Turma da Mônica — O Maior Gibi do Mundo!, published by Panini Comics Brasil and Mauricio de Sousa Produções. The comic book measures 69.9 cm by 99.8 cm (2 ft 3.51 in by 3 ft 3.29 in). The 18-page comic book had a print run of 120 copies.
With the July 2021 publication of the 201st collected volume of his manga series Golgo 13, Japanese manga artist Takao Saito was awarded the Guinness World Records title for "Most volumes published for a single manga series." Golgo 13 has been continuously serialized in the Japanese magazine Big Comic since October 1968, which also makes it the oldest manga still in publication. | [
{
"paragraph_id": 0,
"text": "A comic book, also called comicbook, comic magazine or simply comic, is a publication that consists of comics art in the form of sequential juxtaposed panels that represent individual scenes. Panels are often accompanied by descriptive prose and written narrative, usually, dialogue contained in word balloons emblematic of the comics art form.",
"title": ""
},
{
"paragraph_id": 1,
"text": "\"Comic Cuts\" was a British comic published from 1890 to 1953. It was preceded by \"Ally Sloper's Half Holiday\" (1884) which is notable for its use of sequential cartoons to unfold narrative. These British comics existed alongside the popular lurid \"Penny dreadfuls\" (such as \"Spring-heeled Jack\"), boys' \"Story papers\" and the humorous Punch (magazine) which was the first to use the term \"cartoon\" in its modern sense of a humorous drawing. The interweaving of drawings and the written word had been pioneered by, among others, William Blake (1757 - 1857) in works such as Blake's \"The Descent Of Christ\" (1804 - 1820).",
"title": ""
},
{
"paragraph_id": 2,
"text": "The first modern (American style) comic book, Famous Funnies, was released in the US in 1934 and was a reprinting of earlier newspaper humor comic strips, which had established many of the story-telling devices used in comics. The term comic book derives from American comic books once being a compilation of comic strips of a humorous tone; however, this practice was replaced by featuring stories of all genres, usually not humorous in tone.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The largest comic book market is Japan. By 1995, the manga market in Japan was valued at ¥586.4 billion ($6–7 billion), with annual sales of 1.9 billion manga books (tankōbon volumes and manga magazines) in Japan, equivalent to 15 issues per person. In 2020 the manga market in Japan reached a new record value of ¥612.5 billion due to a fast growth of digital manga sales as well as an increase in print sales. The comic book market in the United States and Canada was valued at $1.09 billion in 2016. As of 2017, the largest comic book publisher in the United States is manga distributor Viz Media, followed by DC Comics and Marvel Comics the original feature full length special edition franchises including Superman, Batman, Wonder Woman, Spider-Man, the Incredible Hulk and the X-Men. The best-selling comic book categories in the US as of 2019 are juvenile children's fiction at 41%, manga at 28% and superhero comics at 10% of the market. Another major comic book market is France, where Franco-Belgian comics and Japanese manga each represent 40% of the market, followed by American comics at 10% market share.",
"title": ""
},
{
"paragraph_id": 4,
"text": "Comic books heavily rely on their organization and visual presentation. Authors dedicate significant attention to aspects like page layout, size, orientation, and the positioning of panels. These characteristics are crucial for effectively conveying the content and messages within the comic book. Key components of comic books encompass panels, speech bubbles (also known as balloons), text lines, and characters. Speech balloons generally take the form of convex containers that hold character dialogue and are connected to the character via a tail element. The tail comprises an origin, path, tip, and directional point. The creation of comic books involves several essential steps: writing, drawing, and coloring. Various technological tools and methods are employed to craft comic books, incorporating concepts such as directions, axes, data, and metrics. Following these formatting guidelines, the process unfolds with writing, drawing, and coloring. In the United States, the term \"comic book\", is generally used for comics periodicals and trade paperbacks while \"graphic novel\" is the term used for standalone books.",
"title": "Structure"
},
{
"paragraph_id": 5,
"text": "Comics as a print medium have existed in the United States since the printing of The Adventures of Mr. Obadiah Oldbuck in 1842 in hardcover, making it the first known American prototype comic book. Proto-comics periodicals began appearing early in the 20th century, with the first comic standard-sized comic being Funnies on Parade. Funnies on Parades was the first book that established the size, duration, and format of the modern comic book. Following this was, Dell Publishing's 36-page Famous Funnies: A Carnival of Comics as the first true newsstand American comic book; Goulart, for example, calls it \"the cornerstone for one of the most lucrative branches of magazine publishing\". In 1905 G.W. Dillingham Company published 24 select strips by the cartoonist Gustave Verbeek in an anthology book called 'The Incredible Upside-Downs of Little Lady Lovekins and Old Man Muffaroo'. The introduction of Jerry Siegel and Joe Shuster's Superman in 1938 turned comic books into a major industry and ushered in the Golden Age of Comic Books. The Golden Age originated the archetype of the superhero. According to historian Michael A. Amundson, appealing comic-book characters helped ease young readers' fear of nuclear war and neutralize anxiety about the questions posed by atomic power.",
"title": "American comic books"
},
{
"paragraph_id": 6,
"text": "Historians generally divide the timeline of the American comic book into eras. The Golden Age of Comic Books began in 1938, with the debut of Superman in Action Comics #1, published by Detective Comics (predecessor of DC Comics), which is generally considered the beginning of the modern comic book as it is known today. The Silver Age of Comic Books is generally considered to date from the first successful revival of the then-dormant superhero form, with the debut of the Flash in Showcase #4 (Oct. 1956). The Silver Age lasted through the late 1960s or early 1970s, during which time Marvel Comics revolutionized the medium with such naturalistic superheroes as Stan Lee and Jack Kirby's Fantastic Four and Lee and Steve Ditko's Spider-Man. The demarcation between the Silver Age and the following era, the Bronze Age of Comic Books, is less well-defined, with the Bronze Age running from the very early 1970s through the mid-1980s. The Modern Age of Comic Books runs from the mid-1980s to the present day.",
"title": "American comic books"
},
{
"paragraph_id": 7,
"text": "A significant event in the timeline of American comic books occurred when psychiatrist Fredric Wertham voiced his criticisms of the medium through his book Seduction of the Innocent (1954). This critique led to the involvement of the American Senate Subcommittee on Juvenile Delinquency, which launched an investigation into comic books. Wertham argued that comic books were accountable for a surge in juvenile delinquency and posed a potential impact on a child's sexuality and moral values. In response to attention from the government and from the media, the US comic book industry set up the Comics Magazine Association of America. The CMAA instilled the Comics Code Authority in 1954 and drafted the self-censorship Comics Code that year, which required all comic books to go through a process of approval. It was not until the 1970s that comic books could be published without passing through the inspection of the CMAA. The Code was made formally defunct in November 2011.",
"title": "American comic books"
},
{
"paragraph_id": 8,
"text": "In the late 1960s and early 1970s, a surge of creativity emerged in what became known as underground comics. Published and distributed independently of the established comics industry, most of such comics reflected the youth counterculture and drug culture of the time. Underground comix \"reflected and commented on the social divisions and tensions of American society\". Many had an uninhibited, often irreverent style; their frank depictions of nudity, sex, profanity, and politics had no parallel outside their precursors, the pornographic and even more obscure \"Tijuana bibles\". Underground comics were almost never sold at newsstands, but rather in such youth-oriented outlets as head shops and record stores, as well as by mail order. The underground comics encouraged creators to publish their work independently so that they would have full ownership rights to their characters.",
"title": "American comic books"
},
{
"paragraph_id": 9,
"text": "Frank Stack's The Adventures of Jesus, published under the name Foolbert Sturgeon, has been credited as the first underground comic; while R. Crumb and the crew of cartoonists who worked on Zap Comix popularized the form.",
"title": "American comic books"
},
{
"paragraph_id": 10,
"text": "The rise of comic book specialty stores in the late 1970s created and paralleled a dedicated market for \"independent\" or \"alternative comics\" in the US. The first such comics included the anthology series Star Reach, published by comic book writer Mike Friedrich from 1974 to 1979, and Harvey Pekar's American Splendor, which continued sporadic publication into the 21st century and which Shari Springer Berman and Robert Pulcini adapted into a 2003 film. Some independent comics continued in the tradition of underground comics. While their content generally remained less explicit, others resembled the output of mainstream publishers in format and genre but were published by smaller artist-owned companies or by single artists. A few (notably RAW) represented experimental attempts to bring comics closer to the status of fine art.",
"title": "American comic books"
},
{
"paragraph_id": 11,
"text": "During the 1970s the \"small press\" culture grew and diversified. By the 1980s, several independent publishers – such as Pacific, Eclipse, First, Comico, and Fantagraphics – had started releasing a wide range of styles and formats—from color-superhero, detective, and science-fiction comic books to black-and-white magazine-format stories of Latin American magical realism.",
"title": "American comic books"
},
{
"paragraph_id": 12,
"text": "A number of small publishers in the 1990s, changed the format and distribution of their comics to more closely resemble non-comics publishing. The \"minicomics\" form, an extremely informal version of self-publishing, arose in the 1980s and became increasingly popular among artists in the 1990s, despite reaching an even more limited audience than the small press.",
"title": "American comic books"
},
{
"paragraph_id": 13,
"text": "Small publishers regularly releasing titles include Avatar Press, Hyperwerks, Raytoons, and Terminal Press, buoyed by such advances in printing technology as digital print-on-demand.",
"title": "American comic books"
},
{
"paragraph_id": 14,
"text": "In 1964, Richard Kyle coined the term \"graphic novel\".",
"title": "American comic books"
},
{
"paragraph_id": 15,
"text": "Precursors of the form existed by the 1920s, which saw a revival of the medieval woodcut tradition by Belgian Frans Masereel, American Lynd Ward and others, including Stan Lee.",
"title": "American comic books"
},
{
"paragraph_id": 16,
"text": "In 1947, Fawcett Publications published \"Comics Novel No. 1\", as the first in an intended series of these \"comics novels\". The story in the first issue was \"Anarcho, Dictator of Death\", a five chapter spy genre tale written by Otto Binder and drawn by Al Carreno. It is readable online in the Digital Comic Museum. The magazine never reached a second issue.",
"title": "American comic books"
},
{
"paragraph_id": 17,
"text": "In 1950, St. John Publications produced the digest-sized, adult-oriented \"picture novel\" It Rhymes with Lust, a 128-page digest by pseudonymous writer \"Drake Waller\" (Arnold Drake and Leslie Waller), penciler Matt Baker and inker Ray Osrin, touted as \"an original full-length novel\" on its cover. \"It Rhymes with Lust\" is also available to read online in the Digital Comic Museum.",
"title": "American comic books"
},
{
"paragraph_id": 18,
"text": "In 1971, writer-artist Gil Kane and collaborators applied a paperback format to their \"comics novel\" Blackmark. Will Eisner popularized the term \"graphic novel\" when he used it on the cover of the paperback edition of his work A Contract with God, and Other Tenement Stories in 1978 and, subsequently, the usage of the term began to increase.",
"title": "American comic books"
},
{
"paragraph_id": 19,
"text": "In 2017, the comic book market size for North America was just over $1 billion with digital sales being flat, book stores having a 1 percent decline, and comic book stores having a 10 percent decline over 2016. The global comic book market saw a substantial 12% growth in 2020, reaching a total worth of USD 8.49 billion. This positive trajectory continued in 2021, with the market's annual valuation surging to USD 9.21 billion. The rising popularity of comic books can be attributed to heightened global interest, driven significantly by collaborative efforts among diverse brands. These collaborations are geared towards producing more engaging and appealing comic content, contributing to the industry's continued growth.",
"title": "American comic books"
},
{
"paragraph_id": 20,
"text": "The 1970s saw the advent of specialty comic book stores. Initially, comic books were marketed by publishers to children because comic books were perceived as children's entertainment. However, with increasing recognition of comics as an art form and the growing pop culture presence of comic book conventions, they are now embraced by many adults.",
"title": "American comic books"
},
{
"paragraph_id": 21,
"text": "Comic book collectors often exhibit a lifelong passion for the stories within comics, often focusing on specific superheroes and striving to gather a complete collection of a particular series. Comics are assigned sequential numbers, and the initial issue of a long-lasting comic book series tends to be both the scarcest and the most coveted among collectors. The introduction of a new character might occur within an existing title. For instance, the first appearance of Spider-Man took place in Amazing Fantasy #15. New characters were frequently introduced in this manner, waiting for an established audience before launching their own titles. Consequently, comics featuring the debut appearance of a significant character can sometimes be even more challenging to locate than the inaugural issue of that character's standalone series.",
"title": "American comic books"
},
{
"paragraph_id": 22,
"text": "Some rare comic books include copies of the unreleased Motion Picture Funnies Weekly #1 from 1939. Eight copies, plus one without a cover, emerged in the estate of the deceased publisher in 1974. The \"Pay Copy\" of this book sold for $43,125 in a 2005 Heritage auction.",
"title": "American comic books"
},
{
"paragraph_id": 23,
"text": "The most valuable American comics have combined rarity and quality with the first appearances of popular and enduring characters. Four comic books have sold for over US$1 million as of December 2010, including two examples of Action Comics #1, the first appearance of Superman, both sold privately through online dealer ComicConnect.com in 2010, and Detective Comics #27, the first appearance of Batman, via public auction.",
"title": "American comic books"
},
{
"paragraph_id": 24,
"text": "Updating the above price obtained for Action Comics #1, the first appearance of Superman, the highest sale on record for this book is $3.2 million, for a 9.0 copy.",
"title": "American comic books"
},
{
"paragraph_id": 25,
"text": "Misprints, promotional comic-dealer incentive printings, and issues with exceptionally low distribution tend to possess scarcity value in the comic book market. The rarest modern comic books include the original press run of The League of Extraordinary Gentlemen #5, which DC executive Paul Levitz recalled and pulped due to the appearance of a vintage Victorian era advertisement for \"Marvel Douche\", which the publisher considered offensive; only 100 copies exist, most of which have been CGC graded. (See Recalled comics for more pulped, recalled, and erroneous comics.)",
"title": "American comic books"
},
{
"paragraph_id": 26,
"text": "In 2000, a company named Comics Guaranty (CGC) initiated the practice of \"slabbing\" comics, which involves encasing them within thick plastic cases and assigning them a numerical grade. This approach inspired the emergence of Comic Book Certification Service. Given the significance of condition in determining the value of rare comics, the concept of grading by an impartial company, one that does not engage in buying or selling comics, seemed promising. Nevertheless, there is an ongoing debate regarding whether the relatively high cost of this grading service is justified and whether it serves the interests of collectors or mainly caters to speculators seeking rapid profits, akin to trading in stocks or fine art. Comic grading has played a role in establishing standards for valuation, which online price guides such as GoCollect and GPAnalysis utilize to provide real-time market value information.",
"title": "American comic books"
},
{
"paragraph_id": 27,
"text": "Collectors also seek out the original artwork pages from comic books, which are perhaps the most rarefied items in the realm of comic book collecting. These pages hold unparalleled scarcity due to the fact that there exists only one unique page of artwork for every page that was printed and published.",
"title": "American comic books"
},
{
"paragraph_id": 28,
"text": "The creation of these original artwork pages involves a collaborative effort: a writer crafts the story, a pencil artist designs the sequential panels on the page, an ink artist goes over the pencil with pen and ink, a letterer provides the dialogue and narration through hand-lettering, and finally, a colorist adds color as the final touch before the pages are sent to the printer.",
"title": "American comic books"
},
{
"paragraph_id": 29,
"text": "When the printer returns the original artwork pages, they are typically returned to the artists themselves. These artists sometimes opt to sell these pages at comic book conventions, in galleries, and at art shows centered around comic book art. The original pages from DC and Marvel, featuring the debut appearances of iconic characters such as Superman, Batman, Wonder Woman, the Flash, Captain Marvel, Spider-Man, the Incredible Hulk, Iron Man, Captain America and the Mighty Thor are regarded as priceless treasures within the comic book world.",
"title": "American comic books"
},
{
"paragraph_id": 30,
"text": "Many early iterations of black characters in comics \"became variations on the 'single stereotypical image of Sambo'.\" Sambo was closely related to the coon stereotype but had some subtle differences. They are both a derogatory way of portraying black characters. \"The name itself, an abbreviation of raccoon, is dehumanizing. As with Sambo, the coon was portrayed as a lazy, easily frightened, chronically idle, inarticulate, buffoon.\" This portrayal \"was of course another attempt to solidify the intellectual inferiority of the black race through popular culture.\" However, in the 1940s there was a change in portrayal of black characters. \"A cursory glance...might give the impression that situations had improved for African Americans in comics.\" In many comics being produced in this time there was a major push for tolerance between races. \"These equality minded heroes began to spring to action just as African Americans were being asked to participate in the war effort.\"",
"title": "American comic books"
},
{
"paragraph_id": 31,
"text": "During this time, a government ran program, the Writers' War Board, became heavily involved in what would be published in comics. \"The Writers' War Board used comic books to shape popular perceptions of race and ethnicity...\" Not only were they using comic books as a means of recruiting all Americans, they were also using it as propaganda to \"[construct] a justification for race-based hatred of America's foreign enemies.\" The Writers' War Board created comics books that were meant to \"[promote] domestic racial harmony\". However, \"these pro-tolerance narratives struggled to overcome the popular and widely understood negative tropes used for decades in American mass culture...\". However, they were not accomplishing this agenda within all of their comics.",
"title": "American comic books"
},
{
"paragraph_id": 32,
"text": "In the comic series Captain Marvel Adventures, there was a character named Steamboat who embodied a collection of highly negative stereotypes prevalent during that period. Surprisingly, the Writers' War Board did not request any alterations to this character despite the problematic portrayal. The removal of Steamboat from the series only came about due to the persistent advocacy of a black youth group based in New York City.\" Originally their request was refused by individuals working on the comic stating, \"Captain Marvel Adventures included many kinds of caricatures 'for the sake of humor'.\" The black youth group responded with \"this is not the Negro race, but your one-and-a-half millions readers will think it so.\" Afterwards, Steamboat disappeared from the comics all together. There was a comic created about the 99th Squadron, also known as the Tuskegee Airmen, an all-black air force unit. Instead of making the comic about their story, the comic was about Hop Harrigan. A white pilot who captures a Nazi, shows him videos of the 99th Squadron defeating his men and then reveals to the Nazi that his men were defeated by African Americans which infuriated him as he sees them as a less superior race and cannot believe they bested his men.\"The Tuskegee Airmen, and images of black aviators appear in just three of the fifty three panels... the pilots of the 99th Squadron have no dialogue and interact with neither Hop Harrigan nor his Nazi captive.\" During this time, they also used black characters in comic books as a means to invalidate the militant black groups that were fighting for equality within the U.S. \"Spider-Man 'made it clear that militant black power was not the remedy for racial injustice'.\" \"The Falcon openly criticized black behavior stating' maybe it's important fo [sic] us to cool things down-so we can protect the rights we been fightin' for'.\" This portrayal and character development of black characters can be partially blamed on the fact that, during this time, \"there had rarely been a black artist or writer allowed in a major comics company.\"",
"title": "American comic books"
},
{
"paragraph_id": 33,
"text": "Asian characters within comic books encountered similar prejudiced treatment as black characters did. They were subjected to dehumanizing depictions, with narratives often portraying them as \"incompetent and subhuman.\" In a 1944 edition of the publication United States Marines, there was a story titled The Smell of the Monkeymen. This narrative portrayed Japanese soldiers as brutish simians, and it depicted their concealed positions being betrayed by their repugnant body odor. Chinese characters received the same treatment. \"By the time the United States entered WWII, negative perceptions of Chinese were an established part of mass culture....\" However, concerned that the Japanese could use America's anti-Chinese material as propaganda they began \"to present a more positive image of America's Chinese allies...\" Just as they tried to show better representation for Black people in comics they did the same for Asian people. However, \"Japanese and Filipino characters were visually indistinguishable. Both groups have grotesque buckteeth, tattered clothing, and bright yellow skin.\" \"Publishers depicted America's Asian allies through derogatory images and language honed over the preceding decades.\" Asian characters were previously portrayed as, \"ghastly yellow demons\". During WWII, \"[every] major superhero worth his spandex devoted himself to the eradication of Asian invaders.\" There was \"a constant relay race in which one Asian culture merely handed off the baton of hatred to another with no perceptible changes in the manner in which the characters would be portrayed.\"",
"title": "American comic books"
},
{
"paragraph_id": 34,
"text": "\"The only specific depiction of a Hispanic superhero did not end well. In 1975, Marvel gave us Hector Ayala (a.k.a The White Tiger).\" \"Although he fought for several years alongside the likes of much more popular heroes such as Spider-Man and Daredevil, he only lasted six years before sales of comics featuring him got so bad that Marvel had him retire. The most famous Hispanic character is Bane, a villain from Batman.\"",
"title": "American comic books"
},
{
"paragraph_id": 35,
"text": "The Native American representation in comic books \"can be summed up in the noble savage stereotype\" \" a recurring theme...urged American indians to abandon their traditional hostility towards the United States. They were the ones painted as intolerant and disrespectful of the dominant concerns of white America\".",
"title": "American comic books"
},
{
"paragraph_id": 36,
"text": "Manga (漫画) are comic books or graphic novels originating from Japan. Most manga conform to a style developed in Japan in the late 19th century, though the art form has a long prehistory in earlier Japanese art. The term manga is used in Japan to refer to both comics and cartooning in general . Outside Japan, the word is typically used to refer to comics originally published in the country.",
"title": "East Asian comics"
},
{
"paragraph_id": 37,
"text": "Dōjinshi (同人誌, fan magazine), fan-made Japanese comics, operate in a far larger market in Japan than the American \"underground comics\" market; the largest dōjinshi fair, Comiket, attracts 500,000 visitors twice a year.",
"title": "East Asian comics"
},
{
"paragraph_id": 38,
"text": "Manhwa (만화) are comic books or graphic novels originating from South Korea. The term manhwa is used in South Korea to refer to both comics and cartooning in general. Outside South Korea, the term usually refers to comics originally published in the country. Manhwa is greatly influenced by Japanese Manga comics though it differs from manga and manhua with its own distinct features.",
"title": "East Asian comics"
},
{
"paragraph_id": 39,
"text": "Webtoons have become popular in South Korea as a new way to read comics. Thanks in part to different censorship rules, color and unique visual effects, and optimization for easier reading on smartphones and computers. More manhwa have made the switch from traditional print manhwa to online webtoons thanks to better pay and more freedom than traditional print manhwa. The webtoon format has also expanded to other countries outside of Korea like China, Japan, Southeast Asia, and Western countries. Major webtoon distributors include Lezhin, Naver, and Kakao.",
"title": "East Asian comics"
},
{
"paragraph_id": 40,
"text": "France and Belgium have a long tradition in comics and comic books, often called BDs (an abbreviation of bandes dessinées, meaning literally \"drawn strips\") in French, and strips in Dutch or Flemish. Belgian comic books originally written in Dutch show the influence of the Francophone \"Franco-Belgian\" comics but have their own distinct style.",
"title": "European comics"
},
{
"paragraph_id": 41,
"text": "Although Ally Sloper's Half Holiday (1884) was aimed at an adult market, publishers quickly targeted a younger demographic, which has led to most publications being for children and has created an association in the public's mind of comics as somewhat juvenile. The Guardian refers to Ally Sloper as \"one of the world's first iconic cartoon characters\", and \"as famous in Victorian Britain as Dennis the Menace would be a century later.\" British comics in the early 20th century typically evolved from illustrated penny dreadfuls of the Victorian era (featuring Sweeney Todd, Dick Turpin and Varney the Vampire). First published in the 1830s, penny dreadfuls were \"Britain's first taste of mass-produced popular culture for the young.\"",
"title": "European comics"
},
{
"paragraph_id": 42,
"text": "The two most popular British comic books, The Beano and The Dandy, were first published by DC Thomson in the 1930s. By 1950 the weekly circulation of both reached two million. Explaining the enormous popularity of comics in the UK during this period, Anita O'Brien, director curator at London's Cartoon Museum, states: \"When comics like the Beano and Dandy were invented back in the 1930s – and through really to the 1950s and 60s – these comics were almost the only entertainment available to children.\" Dennis the Menace was created in the 1950s, which saw sales for The Beano soar. He features in the cover of The Beano, with the BBC referring to him as the \"definitive naughty boy of the comic world.\"",
"title": "European comics"
},
{
"paragraph_id": 43,
"text": "In 1954, Tiger comics introduced Roy of the Rovers, the hugely popular football based strip recounting the life of Roy Race and the team he played for, Melchester Rovers. The stock media phrase \"real 'Roy of the Rovers' stuff\" is often used by football writers, commentators and fans when describing displays of great skill, or surprising results that go against the odds, in reference to the dramatic storylines that were the strip's trademark. Other comic books such as Eagle, Valiant, Warrior, Viz and 2000 AD also flourished. Some comics, such as Judge Dredd and other 2000 AD titles, have been published in a tabloid form. Underground comics and \"small press\" titles have also appeared in the UK, notably Oz and Escape Magazine.",
"title": "European comics"
},
{
"paragraph_id": 44,
"text": "The content of Action, another title aimed at children and launched in the mid-1970s, became the subject of discussion in the House of Commons. Although on a smaller scale than similar investigations in the US, such concerns led to a moderation of content published within British comics. Such moderation never became formalized to the extent of promulgating a code, nor did it last long. The UK has also established a healthy market in the reprinting and repackaging of material, notably material originating in the US. The lack of reliable supplies of American comic books led to a variety of black-and-white reprints, including Marvel's monster comics of the 1950s, Fawcett's Captain Marvel, and other characters such as Sheena, Mandrake the Magician, and the Phantom. Several reprint companies became involved in repackaging American material for the British market, notably the importer and distributor Thorpe & Porter. Marvel Comics established a UK office in 1972. DC Comics and Dark Horse Comics also opened offices in the 1990s. The repackaging of European material has occurred less frequently, although The Adventures of Tintin and Asterix serials have been successfully translated and repackaged in softcover books. The number of European comics available in the UK has increased in the last two decades. The British company Cinebook, founded in 2005, has released English translated versions of many European series.",
"title": "European comics"
},
{
"paragraph_id": 45,
"text": "In the 1980s, a resurgence of British writers and artists gained prominence in mainstream comic books, which was dubbed the \"British Invasion\" in comic book history. These writers and artists brought with them their own mature themes and philosophy such as anarchy, controversy and politics common in British media. These elements would pave the way for mature and \"darker and edgier\" comic books and jump start the Modern Age of Comics. Writers included Alan Moore, famous for his V for Vendetta, From Hell, Watchmen, Marvelman, and The League of Extraordinary Gentlemen; Neil Gaiman with The Sandman mythos and Books of Magic; Warren Ellis, creator of Transmetropolitan and Planetary; and others such as Mark Millar, creator of Wanted and Kick-Ass. The comic book series John Constantine, Hellblazer, which is largely set in Britain and starring the magician John Constantine, paved the way for British writers such as Jamie Delano.",
"title": "European comics"
},
{
"paragraph_id": 46,
"text": "The English musician Peter Gabriel issued in 2000 The Story of OVO which was released in a CD-booklet-shaped comic book as part of the CD edition with the title \"OVO The Millennium Show\". The 2000 Millennium Dome Show based on it.",
"title": "European comics"
},
{
"paragraph_id": 47,
"text": "At Christmas, publishers repackage and commission material for comic annuals, printed and bound as hardcover A4-size books; \"Rupert\" supplies a famous example of the British comic annual. DC Thomson also repackages The Broons and Oor Wullie strips in softcover A4-size books for the holiday season.",
"title": "European comics"
},
{
"paragraph_id": 48,
"text": "On 19 March 2012, the British postal service, the Royal Mail, released a set of stamps depicting British comic book characters and series. The collection featured The Beano, The Dandy, Eagle, The Topper, Roy of the Rovers, Bunty, Buster, Valiant, Twinkle and 2000 AD.",
"title": "European comics"
},
{
"paragraph_id": 49,
"text": "It has been stated that the 13th century Cantigas de Santa María could be considered as the first Spanish \"comic\", although comic books (also known in Spain as historietas or tebeos) made their debut around 1857. The magazine TBO was influential in popularizing the medium. After the Spanish Civil War, the Franco regime imposed strict censorship in all media: superhero comics were forbidden and as a result, comic heroes were based on historical fiction (in 1944 the medieval hero El Guerrero del Antifaz was created by Manuel Gago and another popular medieval hero, Capitán Trueno, was created in 1956 by Víctor Mora and Miguel Ambrosio Zaragoza). Two publishing houses — Editorial Bruguera and Editorial Valenciana — dominated the Spanish comics market during its golden age (1950–1970). The most popular comics showed a recognizable style of slapstick humor (influenced by Franco-Belgian authors such as Franquin): Escobar's Carpanta and Zipi y Zape, Vázquez's Las hermanas Gilda and Anacleto, Ibáñez's Mortadelo y Filemón and 13. Rue del Percebe or Jan's Superlópez. After the end of the Francoist period, there was an increased interest in adult comics with magazines such as Totem, El Jueves, 1984, and El Víbora, and works such as Paracuellos by Carlos Giménez.",
"title": "European comics"
},
{
"paragraph_id": 50,
"text": "Spanish artists have traditionally worked in other markets finding great success, either in the American (e.g., Eisner Award winners Sergio Aragonés, Salvador Larroca, Gabriel Hernández Walta, Marcos Martín or David Aja), the British (e.g., Carlos Ezquerra, co-creator of Judge Dredd) or the Franco-Belgian one (e.g., Fauve d'Or winner Julio Ribera or Blacksad authors Juan Díaz Canales and Juanjo Guarnido).",
"title": "European comics"
},
{
"paragraph_id": 51,
"text": "In Italy, comics (known in Italian as fumetti) made their debut as humor strips at the end of the 19th century, and later evolved into adventure stories. After World War II, however, artists like Hugo Pratt and Guido Crepax exposed Italian comics to an international audience. Popular comic books such as Diabolik or the Bonelli line—namely Tex Willer or Dylan Dog—remain best-sellers.",
"title": "European comics"
},
{
"paragraph_id": 52,
"text": "Mainstream comics are usually published on a monthly basis, in a black-and-white digest size format, with approximately 100 to 132 pages. Collections of classic material for the most famous characters, usually with more than 200 pages, are also common. Author comics are published in the French BD format, with an example being Pratt's Corto Maltese.",
"title": "European comics"
},
{
"paragraph_id": 53,
"text": "Italian cartoonists show the influence of comics from other countries, including France, Belgium, Spain, and Argentina. Italy is also famous for being one of the foremost producers of Walt Disney comic stories outside the US; Donald Duck's superhero alter ego, Paperinik, known in English as Superduck, was created in Italy.",
"title": "European comics"
},
{
"paragraph_id": 54,
"text": "The comic book industry has struggled with distribution issues throughout its history, as numerous mainstream retailers have been hesitant to stock substantial quantities of the most engaging and sought-after comics. The smartphone and the tablet have turned out to be an ideal medium for online distribution.",
"title": "Distribution"
},
{
"paragraph_id": 55,
"text": "On 13 November 2007, Marvel Comics launched Marvel Digital Comics Unlimited, a subscription service allowing readers to read many comics from Marvel's history online. The service also includes periodic release new comics not available elsewhere. With the release of Avenging Spider-Man #1, Marvel also became the first publisher to provide free digital copies as part of the print copy of the comic book.",
"title": "Distribution"
},
{
"paragraph_id": 56,
"text": "With the growing popularity of smartphones and tablets, many major publishers have begun releasing titles in digital form. The most popular platform is comiXology. Some platforms, such as Graphicly, have shut down.",
"title": "Distribution"
},
{
"paragraph_id": 57,
"text": "Numerous libraries house extensive collections of comics in the form of graphic novels. This serves as a convenient means for the general public to become acquainted with the medium.",
"title": "Comic collections in libraries"
},
{
"paragraph_id": 58,
"text": "In 2015, the Japanese manga artist Eiichiro Oda was awarded the Guinness World Records title for having the \"Most copies published for the same comic book series by a single author\". His manga series One Piece, which he writes and illustrates, has been serialized in the Japanese magazine Weekly Shōnen Jump since December 1997, and by 2015, 77 collected volumes had been released. Guinness World Records reported in their announcement that the collected volumes of the series had sold a total of 320,866,000 units. One Piece also holds the Guinness World Records title for \"Most copies published for the same manga series\".",
"title": "Guinness World Records"
},
{
"paragraph_id": 59,
"text": "On 5 August 2018, the Guinness World Records title for the \"Largest comic book ever published\" was awarded to the Brazilian comic book Turma da Mônica — O Maior Gibi do Mundo!, published by Panini Comics Brasil and Mauricio de Sousa Produções. The comic book measures 69.9 cm by 99.8 cm (2 ft 3.51 in by 3 ft 3.29 in). The 18-page comic book had a print run of 120 copies.",
"title": "Guinness World Records"
},
{
"paragraph_id": 60,
"text": "With the July 2021 publication of the 201st collected volume of his manga series Golgo 13, Japanese manga artist Takao Saito was awarded the Guinness World Records title for \"Most volumes published for a single manga series.\" Golgo 13 has been continuously serialized in the Japanese magazine Big Comic since October 1968, which also makes it the oldest manga still in publication.",
"title": "Guinness World Records"
}
] | A comic book, also called comicbook, comic magazine or simply comic, is a publication that consists of comics art in the form of sequential juxtaposed panels that represent individual scenes. Panels are often accompanied by descriptive prose and written narrative, usually, dialogue contained in word balloons emblematic of the comics art form. "Comic Cuts" was a British comic published from 1890 to 1953. It was preceded by "Ally Sloper's Half Holiday" (1884) which is notable for its use of sequential cartoons to unfold narrative. These British comics existed alongside the popular lurid "Penny dreadfuls", boys' "Story papers" and the humorous Punch (magazine) which was the first to use the term "cartoon" in its modern sense of a humorous drawing. The interweaving of drawings and the written word had been pioneered by, among others, William Blake in works such as Blake's "The Descent Of Christ". The first modern comic book, Famous Funnies, was released in the US in 1934 and was a reprinting of earlier newspaper humor comic strips, which had established many of the story-telling devices used in comics. The term comic book derives from American comic books once being a compilation of comic strips of a humorous tone; however, this practice was replaced by featuring stories of all genres, usually not humorous in tone. The largest comic book market is Japan. By 1995, the manga market in Japan was valued at ¥586.4 billion, with annual sales of 1.9 billion manga books in Japan, equivalent to 15 issues per person. In 2020 the manga market in Japan reached a new record value of ¥612.5 billion due to a fast growth of digital manga sales as well as an increase in print sales. The comic book market in the United States and Canada was valued at $1.09 billion in 2016. As of 2017, the largest comic book publisher in the United States is manga distributor Viz Media, followed by DC Comics and Marvel Comics the original feature full length special edition franchises including Superman, Batman, Wonder Woman, Spider-Man, the Incredible Hulk and the X-Men. The best-selling comic book categories in the US as of 2019 are juvenile children's fiction at 41%, manga at 28% and superhero comics at 10% of the market. Another major comic book market is France, where Franco-Belgian comics and Japanese manga each represent 40% of the market, followed by American comics at 10% market share. | 2001-11-14T15:44:00Z | 2023-12-18T07:37:58Z | [
"Template:JPY",
"Template:US$",
"Template:Comics",
"Template:Comics navbar",
"Template:See also",
"Template:Commons category",
"Template:Lang",
"Template:Cite thesis",
"Template:Authority control",
"Template:Portal",
"Template:Sic",
"Template:Nihongo3",
"Template:Reflist",
"Template:Cite press release",
"Template:Attribution needed",
"Template:About",
"Template:As of",
"Template:Cite web",
"Template:Cite book",
"Template:Citation",
"Template:Short description",
"Template:Cn",
"Template:Cite news",
"Template:Cite journal",
"Template:Cbignore",
"Template:Nbsp",
"Template:Cleanup section",
"Template:Media series",
"Template:Use dmy dates",
"Template:Dubious",
"Template:Webarchive",
"Template:ISBN",
"Template:Main"
] | https://en.wikipedia.org/wiki/Comic_book |
6,233 | Connected space | In topology and related branches of mathematics, a connected space is a topological space that cannot be represented as the union of two or more disjoint non-empty open subsets. Connectedness is one of the principal topological properties that are used to distinguish topological spaces.
A subset of a topological space X {\displaystyle X} is a connected set if it is a connected space when viewed as a subspace of X {\displaystyle X} .
Some related but stronger conditions are path connected, simply connected, and n {\displaystyle n} -connected. Another related notion is locally connected, which neither implies nor follows from connectedness.
A topological space X {\displaystyle X} is said to be disconnected if it is the union of two disjoint non-empty open sets. Otherwise, X {\displaystyle X} is said to be connected. A subset of a topological space is said to be connected if it is connected under its subspace topology. Some authors exclude the empty set (with its unique topology) as a connected space, but this article does not follow that practice.
For a topological space X {\displaystyle X} the following conditions are equivalent:
Historically this modern formulation of the notion of connectedness (in terms of no partition of X {\displaystyle X} into two separated sets) first appeared (independently) with N.J. Lennes, Frigyes Riesz, and Felix Hausdorff at the beginning of the 20th century. See for details.
Given some point x {\displaystyle x} in a topological space X , {\displaystyle X,} the union of any collection of connected subsets such that each contains x {\displaystyle x} will once again be a connected subset. The connected component of a point x {\displaystyle x} in X {\displaystyle X} is the union of all connected subsets of X {\displaystyle X} that contain x ; {\displaystyle x;} it is the unique largest (with respect to ⊆ {\displaystyle \subseteq } ) connected subset of X {\displaystyle X} that contains x . {\displaystyle x.} The maximal connected subsets (ordered by inclusion ⊆ {\displaystyle \subseteq } ) of a non-empty topological space are called the connected components of the space. The components of any topological space X {\displaystyle X} form a partition of X {\displaystyle X} : they are disjoint, non-empty and their union is the whole space. Every component is a closed subset of the original space. It follows that, in the case where their number is finite, each component is also an open subset. However, if their number is infinite, this might not be the case; for instance, the connected components of the set of the rational numbers are the one-point sets (singletons), which are not open. Proof: Any two distinct rational numbers q 1 < q 2 {\displaystyle q_{1}<q_{2}} are in different components. Take an irrational number q 1 < r < q 2 , {\displaystyle q_{1}<r<q_{2},} and then set A = { q ∈ Q : q < r } {\displaystyle A=\{q\in \mathbb {Q} :q<r\}} and B = { q ∈ Q : q > r } . {\displaystyle B=\{q\in \mathbb {Q} :q>r\}.} Then ( A , B ) {\displaystyle (A,B)} is a separation of Q , {\displaystyle \mathbb {Q} ,} and q 1 ∈ A , q 2 ∈ B {\displaystyle q_{1}\in A,q_{2}\in B} . Thus each component is a one-point set.
Let Γ x {\displaystyle \Gamma _{x}} be the connected component of x {\displaystyle x} in a topological space X , {\displaystyle X,} and Γ x ′ {\displaystyle \Gamma _{x}'} be the intersection of all clopen sets containing x {\displaystyle x} (called quasi-component of x . {\displaystyle x.} ) Then Γ x ⊂ Γ x ′ {\displaystyle \Gamma _{x}\subset \Gamma '_{x}} where the equality holds if X {\displaystyle X} is compact Hausdorff or locally connected.
A space in which all components are one-point sets is called totally disconnected. Related to this property, a space X {\displaystyle X} is called totally separated if, for any two distinct elements x {\displaystyle x} and y {\displaystyle y} of X {\displaystyle X} , there exist disjoint open sets U {\displaystyle U} containing x {\displaystyle x} and V {\displaystyle V} containing y {\displaystyle y} such that X {\displaystyle X} is the union of U {\displaystyle U} and V {\displaystyle V} . Clearly, any totally separated space is totally disconnected, but the converse does not hold. For example take two copies of the rational numbers Q {\displaystyle \mathbb {Q} } , and identify them at every point except zero. The resulting space, with the quotient topology, is totally disconnected. However, by considering the two copies of zero, one sees that the space is not totally separated. In fact, it is not even Hausdorff, and the condition of being totally separated is strictly stronger than the condition of being Hausdorff.
An example of a space that is not connected is a plane with an infinite line deleted from it. Other examples of disconnected spaces (that is, spaces which are not connected) include the plane with an annulus removed, as well as the union of two disjoint closed disks, where all examples of this paragraph bear the subspace topology induced by two-dimensional Euclidean space.
A path-connected space is a stronger notion of connectedness, requiring the structure of a path. A path from a point x {\displaystyle x} to a point y {\displaystyle y} in a topological space X {\displaystyle X} is a continuous function f {\displaystyle f} from the unit interval [ 0 , 1 ] {\displaystyle [0,1]} to X {\displaystyle X} with f ( 0 ) = x {\displaystyle f(0)=x} and f ( 1 ) = y {\displaystyle f(1)=y} . A path-component of X {\displaystyle X} is an equivalence class of X {\displaystyle X} under the equivalence relation which makes x {\displaystyle x} equivalent to y {\displaystyle y} if there is a path from x {\displaystyle x} to y {\displaystyle y} . The space X {\displaystyle X} is said to be path-connected (or pathwise connected or 0 {\displaystyle \mathbf {0} } -connected) if there is exactly one path-component, i.e. if there is a path joining any two points in X {\displaystyle X} . Again, many authors exclude the empty space (by this definition, however, the empty space is not path-connected because it has zero path-components; there is a unique equivalence relation on the empty set which has zero equivalence classes).
Every path-connected space is connected. The converse is not always true: examples of connected spaces that are not path-connected include the extended long line L ∗ {\displaystyle L^{*}} and the topologist's sine curve.
Subsets of the real line R {\displaystyle \mathbb {R} } are connected if and only if they are path-connected; these subsets are the intervals of R {\displaystyle \mathbb {R} } . Also, open subsets of R n {\displaystyle \mathbb {R} ^{n}} or C n {\displaystyle \mathbb {C} ^{n}} are connected if and only if they are path-connected. Additionally, connectedness and path-connectedness are the same for finite topological spaces.
A space X {\displaystyle X} is said to be arc-connected or arcwise connected if any two topologically distinguishable points can be joined by an arc, which is an embedding f : [ 0 , 1 ] → X {\displaystyle f:[0,1]\to X} . An arc-component of X {\displaystyle X} is a maximal arc-connected subset of X {\displaystyle X} ; or equivalently an equivalence class of the equivalence relation of whether two points can be joined by an arc or by a path whose points are topologically indistinguishable.
Every Hausdorff space that is path-connected is also arc-connected; more generally this is true for a Δ {\displaystyle \Delta } -Hausdorff space, which is a space where each image of a path is closed. An example of a space which is path-connected but not arc-connected is given by the line with two origins; its two copies of 0 {\displaystyle 0} can be connected by a path but not by an arc.
Intuition for path-connected spaces does not readily transfer to arc-connected spaces. Let X {\displaystyle X} be the line with two origins. The following are facts whose analogues hold for path-connected spaces, but do not hold for arc-connected spaces:
A topological space is said to be locally connected at a point x {\displaystyle x} if every neighbourhood of x {\displaystyle x} contains a connected open neighbourhood. It is locally connected if it has a base of connected sets. It can be shown that a space X {\displaystyle X} is locally connected if and only if every component of every open set of X {\displaystyle X} is open.
Similarly, a topological space is said to be locally path-connected if it has a base of path-connected sets. An open subset of a locally path-connected space is connected if and only if it is path-connected. This generalizes the earlier statement about R n {\displaystyle \mathbb {R} ^{n}} and C n {\displaystyle \mathbb {C} ^{n}} , each of which is locally path-connected. More generally, any topological manifold is locally path-connected.
Locally connected does not imply connected, nor does locally path-connected imply path connected. A simple example of a locally connected (and locally path-connected) space that is not connected (or path-connected) is the union of two separated intervals in R {\displaystyle \mathbb {R} } , such as ( 0 , 1 ) ∪ ( 2 , 3 ) {\displaystyle (0,1)\cup (2,3)} .
A classical example of a connected space that is not locally connected is the so called topologist's sine curve, defined as T = { ( 0 , 0 ) } ∪ { ( x , sin ( 1 x ) ) : x ∈ ( 0 , 1 ] } {\displaystyle T=\{(0,0)\}\cup \left\{\left(x,\sin \left({\tfrac {1}{x}}\right)\right):x\in (0,1]\right\}} , with the Euclidean topology induced by inclusion in R 2 {\displaystyle \mathbb {R} ^{2}} .
The intersection of connected sets is not necessarily connected.
The union of connected sets is not necessarily connected, as can be seen by considering X = ( 0 , 1 ) ∪ ( 1 , 2 ) {\displaystyle X=(0,1)\cup (1,2)} .
Each ellipse is a connected set, but the union is not connected, since it can be partitioned to two disjoint open sets U {\displaystyle U} and V {\displaystyle V} .
This means that, if the union X {\displaystyle X} is disconnected, then the collection { X i } {\displaystyle \{X_{i}\}} can be partitioned to two sub-collections, such that the unions of the sub-collections are disjoint and open in X {\displaystyle X} (see picture). This implies that in several cases, a union of connected sets is necessarily connected. In particular:
The set difference of connected sets is not necessarily connected. However, if X ⊇ Y {\displaystyle X\supseteq Y} and their difference X ∖ Y {\displaystyle X\setminus Y} is disconnected (and thus can be written as a union of two open sets X 1 {\displaystyle X_{1}} and X 2 {\displaystyle X_{2}} ), then the union of Y {\displaystyle Y} with each such component is connected (i.e. Y ∪ X i {\displaystyle Y\cup X_{i}} is connected for all i {\displaystyle i} ).
By contradiction, suppose Y ∪ X 1 {\displaystyle Y\cup X_{1}} is not connected. So it can be written as the union of two disjoint open sets, e.g. Y ∪ X 1 = Z 1 ∪ Z 2 {\displaystyle Y\cup X_{1}=Z_{1}\cup Z_{2}} . Because Y {\displaystyle Y} is connected, it must be entirely contained in one of these components, say Z 1 {\displaystyle Z_{1}} , and thus Z 2 {\displaystyle Z_{2}} is contained in X 1 {\displaystyle X_{1}} . Now we know that:
The two sets in the last union are disjoint and open in X {\displaystyle X} , so there is a separation of X {\displaystyle X} , contradicting the fact that X {\displaystyle X} is connected.
Graphs have path connected subsets, namely those subsets for which every pair of points has a path of edges joining them. But it is not always possible to find a topology on the set of points which induces the same connected sets. The 5-cycle graph (and any n {\displaystyle n} -cycle with n > 3 {\displaystyle n>3} odd) is one such example.
As a consequence, a notion of connectedness can be formulated independently of the topology on a space. To wit, there is a category of connective spaces consisting of sets with collections of connected subsets satisfying connectivity axioms; their morphisms are those functions which map connected sets to connected sets (Muscat & Buhagiar 2006). Topological spaces and graphs are special cases of connective spaces; indeed, the finite connective spaces are precisely the finite graphs.
However, every graph can be canonically made into a topological space, by treating vertices as points and edges as copies of the unit interval (see topological graph theory#Graphs as topological spaces). Then one can show that the graph is connected (in the graph theoretical sense) if and only if it is connected as a topological space.
There are stronger forms of connectedness for topological spaces, for instance:
In general, any path connected space must be connected but there exist connected spaces that are not path connected. The deleted comb space furnishes such an example, as does the above-mentioned topologist's sine curve. | [
{
"paragraph_id": 0,
"text": "In topology and related branches of mathematics, a connected space is a topological space that cannot be represented as the union of two or more disjoint non-empty open subsets. Connectedness is one of the principal topological properties that are used to distinguish topological spaces.",
"title": ""
},
{
"paragraph_id": 1,
"text": "A subset of a topological space X {\\displaystyle X} is a connected set if it is a connected space when viewed as a subspace of X {\\displaystyle X} .",
"title": ""
},
{
"paragraph_id": 2,
"text": "Some related but stronger conditions are path connected, simply connected, and n {\\displaystyle n} -connected. Another related notion is locally connected, which neither implies nor follows from connectedness.",
"title": ""
},
{
"paragraph_id": 3,
"text": "A topological space X {\\displaystyle X} is said to be disconnected if it is the union of two disjoint non-empty open sets. Otherwise, X {\\displaystyle X} is said to be connected. A subset of a topological space is said to be connected if it is connected under its subspace topology. Some authors exclude the empty set (with its unique topology) as a connected space, but this article does not follow that practice.",
"title": "Formal definition"
},
{
"paragraph_id": 4,
"text": "For a topological space X {\\displaystyle X} the following conditions are equivalent:",
"title": "Formal definition"
},
{
"paragraph_id": 5,
"text": "Historically this modern formulation of the notion of connectedness (in terms of no partition of X {\\displaystyle X} into two separated sets) first appeared (independently) with N.J. Lennes, Frigyes Riesz, and Felix Hausdorff at the beginning of the 20th century. See for details.",
"title": "Formal definition"
},
{
"paragraph_id": 6,
"text": "Given some point x {\\displaystyle x} in a topological space X , {\\displaystyle X,} the union of any collection of connected subsets such that each contains x {\\displaystyle x} will once again be a connected subset. The connected component of a point x {\\displaystyle x} in X {\\displaystyle X} is the union of all connected subsets of X {\\displaystyle X} that contain x ; {\\displaystyle x;} it is the unique largest (with respect to ⊆ {\\displaystyle \\subseteq } ) connected subset of X {\\displaystyle X} that contains x . {\\displaystyle x.} The maximal connected subsets (ordered by inclusion ⊆ {\\displaystyle \\subseteq } ) of a non-empty topological space are called the connected components of the space. The components of any topological space X {\\displaystyle X} form a partition of X {\\displaystyle X} : they are disjoint, non-empty and their union is the whole space. Every component is a closed subset of the original space. It follows that, in the case where their number is finite, each component is also an open subset. However, if their number is infinite, this might not be the case; for instance, the connected components of the set of the rational numbers are the one-point sets (singletons), which are not open. Proof: Any two distinct rational numbers q 1 < q 2 {\\displaystyle q_{1}<q_{2}} are in different components. Take an irrational number q 1 < r < q 2 , {\\displaystyle q_{1}<r<q_{2},} and then set A = { q ∈ Q : q < r } {\\displaystyle A=\\{q\\in \\mathbb {Q} :q<r\\}} and B = { q ∈ Q : q > r } . {\\displaystyle B=\\{q\\in \\mathbb {Q} :q>r\\}.} Then ( A , B ) {\\displaystyle (A,B)} is a separation of Q , {\\displaystyle \\mathbb {Q} ,} and q 1 ∈ A , q 2 ∈ B {\\displaystyle q_{1}\\in A,q_{2}\\in B} . Thus each component is a one-point set.",
"title": "Formal definition"
},
{
"paragraph_id": 7,
"text": "Let Γ x {\\displaystyle \\Gamma _{x}} be the connected component of x {\\displaystyle x} in a topological space X , {\\displaystyle X,} and Γ x ′ {\\displaystyle \\Gamma _{x}'} be the intersection of all clopen sets containing x {\\displaystyle x} (called quasi-component of x . {\\displaystyle x.} ) Then Γ x ⊂ Γ x ′ {\\displaystyle \\Gamma _{x}\\subset \\Gamma '_{x}} where the equality holds if X {\\displaystyle X} is compact Hausdorff or locally connected.",
"title": "Formal definition"
},
{
"paragraph_id": 8,
"text": "A space in which all components are one-point sets is called totally disconnected. Related to this property, a space X {\\displaystyle X} is called totally separated if, for any two distinct elements x {\\displaystyle x} and y {\\displaystyle y} of X {\\displaystyle X} , there exist disjoint open sets U {\\displaystyle U} containing x {\\displaystyle x} and V {\\displaystyle V} containing y {\\displaystyle y} such that X {\\displaystyle X} is the union of U {\\displaystyle U} and V {\\displaystyle V} . Clearly, any totally separated space is totally disconnected, but the converse does not hold. For example take two copies of the rational numbers Q {\\displaystyle \\mathbb {Q} } , and identify them at every point except zero. The resulting space, with the quotient topology, is totally disconnected. However, by considering the two copies of zero, one sees that the space is not totally separated. In fact, it is not even Hausdorff, and the condition of being totally separated is strictly stronger than the condition of being Hausdorff.",
"title": "Formal definition"
},
{
"paragraph_id": 9,
"text": "An example of a space that is not connected is a plane with an infinite line deleted from it. Other examples of disconnected spaces (that is, spaces which are not connected) include the plane with an annulus removed, as well as the union of two disjoint closed disks, where all examples of this paragraph bear the subspace topology induced by two-dimensional Euclidean space.",
"title": "Examples"
},
{
"paragraph_id": 10,
"text": "A path-connected space is a stronger notion of connectedness, requiring the structure of a path. A path from a point x {\\displaystyle x} to a point y {\\displaystyle y} in a topological space X {\\displaystyle X} is a continuous function f {\\displaystyle f} from the unit interval [ 0 , 1 ] {\\displaystyle [0,1]} to X {\\displaystyle X} with f ( 0 ) = x {\\displaystyle f(0)=x} and f ( 1 ) = y {\\displaystyle f(1)=y} . A path-component of X {\\displaystyle X} is an equivalence class of X {\\displaystyle X} under the equivalence relation which makes x {\\displaystyle x} equivalent to y {\\displaystyle y} if there is a path from x {\\displaystyle x} to y {\\displaystyle y} . The space X {\\displaystyle X} is said to be path-connected (or pathwise connected or 0 {\\displaystyle \\mathbf {0} } -connected) if there is exactly one path-component, i.e. if there is a path joining any two points in X {\\displaystyle X} . Again, many authors exclude the empty space (by this definition, however, the empty space is not path-connected because it has zero path-components; there is a unique equivalence relation on the empty set which has zero equivalence classes).",
"title": "Path connectedness"
},
{
"paragraph_id": 11,
"text": "Every path-connected space is connected. The converse is not always true: examples of connected spaces that are not path-connected include the extended long line L ∗ {\\displaystyle L^{*}} and the topologist's sine curve.",
"title": "Path connectedness"
},
{
"paragraph_id": 12,
"text": "Subsets of the real line R {\\displaystyle \\mathbb {R} } are connected if and only if they are path-connected; these subsets are the intervals of R {\\displaystyle \\mathbb {R} } . Also, open subsets of R n {\\displaystyle \\mathbb {R} ^{n}} or C n {\\displaystyle \\mathbb {C} ^{n}} are connected if and only if they are path-connected. Additionally, connectedness and path-connectedness are the same for finite topological spaces.",
"title": "Path connectedness"
},
{
"paragraph_id": 13,
"text": "A space X {\\displaystyle X} is said to be arc-connected or arcwise connected if any two topologically distinguishable points can be joined by an arc, which is an embedding f : [ 0 , 1 ] → X {\\displaystyle f:[0,1]\\to X} . An arc-component of X {\\displaystyle X} is a maximal arc-connected subset of X {\\displaystyle X} ; or equivalently an equivalence class of the equivalence relation of whether two points can be joined by an arc or by a path whose points are topologically indistinguishable.",
"title": "Arc connectedness"
},
{
"paragraph_id": 14,
"text": "Every Hausdorff space that is path-connected is also arc-connected; more generally this is true for a Δ {\\displaystyle \\Delta } -Hausdorff space, which is a space where each image of a path is closed. An example of a space which is path-connected but not arc-connected is given by the line with two origins; its two copies of 0 {\\displaystyle 0} can be connected by a path but not by an arc.",
"title": "Arc connectedness"
},
{
"paragraph_id": 15,
"text": "Intuition for path-connected spaces does not readily transfer to arc-connected spaces. Let X {\\displaystyle X} be the line with two origins. The following are facts whose analogues hold for path-connected spaces, but do not hold for arc-connected spaces:",
"title": "Arc connectedness"
},
{
"paragraph_id": 16,
"text": "A topological space is said to be locally connected at a point x {\\displaystyle x} if every neighbourhood of x {\\displaystyle x} contains a connected open neighbourhood. It is locally connected if it has a base of connected sets. It can be shown that a space X {\\displaystyle X} is locally connected if and only if every component of every open set of X {\\displaystyle X} is open.",
"title": "Local connectedness"
},
{
"paragraph_id": 17,
"text": "Similarly, a topological space is said to be locally path-connected if it has a base of path-connected sets. An open subset of a locally path-connected space is connected if and only if it is path-connected. This generalizes the earlier statement about R n {\\displaystyle \\mathbb {R} ^{n}} and C n {\\displaystyle \\mathbb {C} ^{n}} , each of which is locally path-connected. More generally, any topological manifold is locally path-connected.",
"title": "Local connectedness"
},
{
"paragraph_id": 18,
"text": "Locally connected does not imply connected, nor does locally path-connected imply path connected. A simple example of a locally connected (and locally path-connected) space that is not connected (or path-connected) is the union of two separated intervals in R {\\displaystyle \\mathbb {R} } , such as ( 0 , 1 ) ∪ ( 2 , 3 ) {\\displaystyle (0,1)\\cup (2,3)} .",
"title": "Local connectedness"
},
{
"paragraph_id": 19,
"text": "A classical example of a connected space that is not locally connected is the so called topologist's sine curve, defined as T = { ( 0 , 0 ) } ∪ { ( x , sin ( 1 x ) ) : x ∈ ( 0 , 1 ] } {\\displaystyle T=\\{(0,0)\\}\\cup \\left\\{\\left(x,\\sin \\left({\\tfrac {1}{x}}\\right)\\right):x\\in (0,1]\\right\\}} , with the Euclidean topology induced by inclusion in R 2 {\\displaystyle \\mathbb {R} ^{2}} .",
"title": "Local connectedness"
},
{
"paragraph_id": 20,
"text": "The intersection of connected sets is not necessarily connected.",
"title": "Set operations"
},
{
"paragraph_id": 21,
"text": "The union of connected sets is not necessarily connected, as can be seen by considering X = ( 0 , 1 ) ∪ ( 1 , 2 ) {\\displaystyle X=(0,1)\\cup (1,2)} .",
"title": "Set operations"
},
{
"paragraph_id": 22,
"text": "Each ellipse is a connected set, but the union is not connected, since it can be partitioned to two disjoint open sets U {\\displaystyle U} and V {\\displaystyle V} .",
"title": "Set operations"
},
{
"paragraph_id": 23,
"text": "This means that, if the union X {\\displaystyle X} is disconnected, then the collection { X i } {\\displaystyle \\{X_{i}\\}} can be partitioned to two sub-collections, such that the unions of the sub-collections are disjoint and open in X {\\displaystyle X} (see picture). This implies that in several cases, a union of connected sets is necessarily connected. In particular:",
"title": "Set operations"
},
{
"paragraph_id": 24,
"text": "The set difference of connected sets is not necessarily connected. However, if X ⊇ Y {\\displaystyle X\\supseteq Y} and their difference X ∖ Y {\\displaystyle X\\setminus Y} is disconnected (and thus can be written as a union of two open sets X 1 {\\displaystyle X_{1}} and X 2 {\\displaystyle X_{2}} ), then the union of Y {\\displaystyle Y} with each such component is connected (i.e. Y ∪ X i {\\displaystyle Y\\cup X_{i}} is connected for all i {\\displaystyle i} ).",
"title": "Set operations"
},
{
"paragraph_id": 25,
"text": "By contradiction, suppose Y ∪ X 1 {\\displaystyle Y\\cup X_{1}} is not connected. So it can be written as the union of two disjoint open sets, e.g. Y ∪ X 1 = Z 1 ∪ Z 2 {\\displaystyle Y\\cup X_{1}=Z_{1}\\cup Z_{2}} . Because Y {\\displaystyle Y} is connected, it must be entirely contained in one of these components, say Z 1 {\\displaystyle Z_{1}} , and thus Z 2 {\\displaystyle Z_{2}} is contained in X 1 {\\displaystyle X_{1}} . Now we know that:",
"title": "Set operations"
},
{
"paragraph_id": 26,
"text": "The two sets in the last union are disjoint and open in X {\\displaystyle X} , so there is a separation of X {\\displaystyle X} , contradicting the fact that X {\\displaystyle X} is connected.",
"title": "Set operations"
},
{
"paragraph_id": 27,
"text": "Graphs have path connected subsets, namely those subsets for which every pair of points has a path of edges joining them. But it is not always possible to find a topology on the set of points which induces the same connected sets. The 5-cycle graph (and any n {\\displaystyle n} -cycle with n > 3 {\\displaystyle n>3} odd) is one such example.",
"title": "Graphs"
},
{
"paragraph_id": 28,
"text": "As a consequence, a notion of connectedness can be formulated independently of the topology on a space. To wit, there is a category of connective spaces consisting of sets with collections of connected subsets satisfying connectivity axioms; their morphisms are those functions which map connected sets to connected sets (Muscat & Buhagiar 2006). Topological spaces and graphs are special cases of connective spaces; indeed, the finite connective spaces are precisely the finite graphs.",
"title": "Graphs"
},
{
"paragraph_id": 29,
"text": "However, every graph can be canonically made into a topological space, by treating vertices as points and edges as copies of the unit interval (see topological graph theory#Graphs as topological spaces). Then one can show that the graph is connected (in the graph theoretical sense) if and only if it is connected as a topological space.",
"title": "Graphs"
},
{
"paragraph_id": 30,
"text": "There are stronger forms of connectedness for topological spaces, for instance:",
"title": "Stronger forms of connectedness"
},
{
"paragraph_id": 31,
"text": "In general, any path connected space must be connected but there exist connected spaces that are not path connected. The deleted comb space furnishes such an example, as does the above-mentioned topologist's sine curve.",
"title": "Stronger forms of connectedness"
}
] | In topology and related branches of mathematics, a connected space is a topological space that cannot be represented as the union of two or more disjoint non-empty open subsets. Connectedness is one of the principal topological properties that are used to distinguish topological spaces. A subset of a topological space X is a connected set if it is a connected space when viewed as a subspace of X . Some related but stronger conditions are path connected, simply connected, and n -connected. Another related notion is locally connected, which neither implies nor follows from connectedness. | 2001-08-31T10:29:54Z | 2023-12-18T09:11:22Z | [
"Template:Multiple image",
"Template:Refbegin",
"Template:Use American English",
"Template:Mvar",
"Template:Harv",
"Template:Portal",
"Template:Reflist",
"Template:Cite journal",
"Template:Cite web",
"Template:MathWorld",
"Template:Short description",
"Template:Cite book",
"Template:Topology",
"Template:Authority control",
"Template:Main",
"Template:Em",
"Template:Math proof",
"Template:Annotated link",
"Template:Eom",
"Template:Refend",
"Template:Visible anchor"
] | https://en.wikipedia.org/wiki/Connected_space |
6,235 | Cell nucleus | The cell nucleus (from Latin nucleus or nuculeus 'kernel, seed'; PL: nuclei) is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support.
The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long strands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating gene expression.
Because the nuclear envelope is impermeable to large molecules, nuclear pores are required to regulate nuclear transport of molecules across the envelope. The pores cross both nuclear membranes, providing a channel through which larger molecules must be actively transported by carrier proteins while allowing free movement of small molecules and ions. Movement of large molecules such as proteins and RNA through the pores is required for both gene expression and the maintenance of chromosomes. Although the interior of the nucleus does not contain any membrane-bound subcompartments, a number of nuclear bodies exist, made up of unique proteins, RNA molecules, and particular parts of the chromosomes. The best-known of these is the nucleolus, involved in the assembly of ribosomes.
The nucleus contains nearly all of the cell's DNA, surrounded by a network of fibrous intermediate filaments called the nuclear matrix, and is enveloped in a double membrane called the nuclear envelope. The nuclear envelope separates the fluid inside the nucleus, called the nucleoplasm, from the rest of the cell. The size of the nucleus is correlated to the size of the cell, and this ratio is reported across a range of cell types and species. In eukaryotes the nucleus in many cells typically occupies 10% of the cell volume. The nucleus is the largest organelle in animal cells. In human cells, the diameter of the nucleus is approximately six micrometres (µm).
The nuclear envelope consists of two membranes, an inner and an outer nuclear membrane, perforated by nuclear pores. Together, these membranes serve to separate the cell's genetic material from the rest of the cell contents, and allow the nucleus to maintain an environment distinct from the rest of the cell. Despite their close apposition around much of the nucleus, the two membranes differ substantially in shape and contents. The inner membrane surrounds the nuclear content, providing its defining edge. Embedded within the inner membrane, various proteins bind the intermediate filaments that give the nucleus its structure. The outer membrane encloses the inner membrane, and is continuous with the adjacent endoplasmic reticulum membrane. As part of the endoplasmic reticulum membrane, the outer nuclear membrane is studded with ribosomes that are actively translating proteins across membrane. The space between the two membranes is called the perinuclear space, and is continuous with the endoplasmic reticulum lumen.
In a mammalian nuclear envelope there are between 3000 and 4000 nuclear pore complexes (NPCs) perforating the envelope. Each NPC contains an eightfold-symmetric ring-shaped structure at a position where the inner and outer membranes fuse. The number of NPCs can vary considerably across cell types; small glial cells only have about a few hundred, with large Purkinje cells having around 20,000. The NPC provides selective transport of molecules between the nucleoplasm and the cytosol. The nuclear pore complex is composed of approximately thirty different proteins known as nucleoporins. The pores are about 60–80 million daltons in molecular weight and consist of around 50 (in yeast) to several hundred proteins (in vertebrates). The pores are 100 nm in total diameter; however, the gap through which molecules freely diffuse is only about 9 nm wide, due to the presence of regulatory systems within the center of the pore. This size selectively allows the passage of small water-soluble molecules while preventing larger molecules, such as nucleic acids and larger proteins, from inappropriately entering or exiting the nucleus. These large molecules must be actively transported into the nucleus instead. Attached to the ring is a structure called the nuclear basket that extends into the nucleoplasm, and a series of filamentous extensions that reach into the cytoplasm. Both structures serve to mediate binding to nuclear transport proteins.
Most proteins, ribosomal subunits, and some RNAs are transported through the pore complexes in a process mediated by a family of transport factors known as karyopherins. Those karyopherins that mediate movement into the nucleus are also called importins, whereas those that mediate movement out of the nucleus are called exportins. Most karyopherins interact directly with their cargo, although some use adaptor proteins. Steroid hormones such as cortisol and aldosterone, as well as other small lipid-soluble molecules involved in intercellular signaling, can diffuse through the cell membrane and into the cytoplasm, where they bind nuclear receptor proteins that are trafficked into the nucleus. There they serve as transcription factors when bound to their ligand; in the absence of a ligand, many such receptors function as histone deacetylases that repress gene expression.
In animal cells, two networks of intermediate filaments provide the nucleus with mechanical support: The nuclear lamina forms an organized meshwork on the internal face of the envelope, while less organized support is provided on the cytosolic face of the envelope. Both systems provide structural support for the nuclear envelope and anchoring sites for chromosomes and nuclear pores.
The nuclear lamina is composed mostly of lamin proteins. Like all proteins, lamins are synthesized in the cytoplasm and later transported to the nucleus interior, where they are assembled before being incorporated into the existing network of nuclear lamina. Lamins found on the cytosolic face of the membrane, such as emerin and nesprin, bind to the cytoskeleton to provide structural support. Lamins are also found inside the nucleoplasm where they form another regular structure, known as the nucleoplasmic veil, that is visible using fluorescence microscopy. The actual function of the veil is not clear, although it is excluded from the nucleolus and is present during interphase. Lamin structures that make up the veil, such as LEM3, bind chromatin and disrupting their structure inhibits transcription of protein-coding genes.
Like the components of other intermediate filaments, the lamin monomer contains an alpha-helical domain used by two monomers to coil around each other, forming a dimer structure called a coiled coil. Two of these dimer structures then join side by side, in an antiparallel arrangement, to form a tetramer called a protofilament. Eight of these protofilaments form a lateral arrangement that is twisted to form a ropelike filament. These filaments can be assembled or disassembled in a dynamic manner, meaning that changes in the length of the filament depend on the competing rates of filament addition and removal.
Mutations in lamin genes leading to defects in filament assembly cause a group of rare genetic disorders known as laminopathies. The most notable laminopathy is the family of diseases known as progeria, which causes the appearance of premature aging in those with the condition. The exact mechanism by which the associated biochemical changes give rise to the aged phenotype is not well understood.
The cell nucleus contains the majority of the cell's genetic material in the form of multiple linear DNA molecules organized into structures called chromosomes. Each human cell contains roughly two meters of DNA. During most of the cell cycle these are organized in a DNA-protein complex known as chromatin, and during cell division the chromatin can be seen to form the well-defined chromosomes familiar from a karyotype. A small fraction of the cell's genes are located instead in the mitochondria.
There are two types of chromatin. Euchromatin is the less compact DNA form, and contains genes that are frequently expressed by the cell. The other type, heterochromatin, is the more compact form, and contains DNA that is infrequently transcribed. This structure is further categorized into facultative heterochromatin, consisting of genes that are organized as heterochromatin only in certain cell types or at certain stages of development, and constitutive heterochromatin that consists of chromosome structural components such as telomeres and centromeres. During interphase the chromatin organizes itself into discrete individual patches, called chromosome territories. Active genes, which are generally found in the euchromatic region of the chromosome, tend to be located towards the chromosome's territory boundary.
Antibodies to certain types of chromatin organization, in particular, nucleosomes, have been associated with a number of autoimmune diseases, such as systemic lupus erythematosus. These are known as anti-nuclear antibodies (ANA) and have also been observed in concert with multiple sclerosis as part of general immune system dysfunction.
The nucleolus is the largest of the discrete densely stained, membraneless structures known as nuclear bodies found in the nucleus. It forms around tandem repeats of rDNA, DNA coding for ribosomal RNA (rRNA). These regions are called nucleolar organizer regions (NOR). The main roles of the nucleolus are to synthesize rRNA and assemble ribosomes. The structural cohesion of the nucleolus depends on its activity, as ribosomal assembly in the nucleolus results in the transient association of nucleolar components, facilitating further ribosomal assembly, and hence further association. This model is supported by observations that inactivation of rDNA results in intermingling of nucleolar structures.
In the first step of ribosome assembly, a protein called RNA polymerase I transcribes rDNA, which forms a large pre-rRNA precursor. This is cleaved into two large rRNA subunits – 5.8S, and 28S, and a small rRNA subunit 18S. The transcription, post-transcriptional processing, and assembly of rRNA occurs in the nucleolus, aided by small nucleolar RNA (snoRNA) molecules, some of which are derived from spliced introns from messenger RNAs encoding genes related to ribosomal function. The assembled ribosomal subunits are the largest structures passed through the nuclear pores.
When observed under the electron microscope, the nucleolus can be seen to consist of three distinguishable regions: the innermost fibrillar centers (FCs), surrounded by the dense fibrillar component (DFC) (that contains fibrillarin and nucleolin), which in turn is bordered by the granular component (GC) (that contains the protein nucleophosmin). Transcription of the rDNA occurs either in the FC or at the FC-DFC boundary, and, therefore, when rDNA transcription in the cell is increased, more FCs are detected. Most of the cleavage and modification of rRNAs occurs in the DFC, while the latter steps involving protein assembly onto the ribosomal subunits occur in the GC.
Besides the nucleolus, the nucleus contains a number of other nuclear bodies. These include Cajal bodies, gemini of Cajal bodies, polymorphic interphase karyosomal association (PIKA), promyelocytic leukaemia (PML) bodies, paraspeckles, and splicing speckles. Although little is known about a number of these domains, they are significant in that they show that the nucleoplasm is not a uniform mixture, but rather contains organized functional subdomains.
Other subnuclear structures appear as part of abnormal disease processes. For example, the presence of small intranuclear rods has been reported in some cases of nemaline myopathy. This condition typically results from mutations in actin, and the rods themselves consist of mutant actin as well as other cytoskeletal proteins.
A nucleus typically contains between one and ten compact structures called Cajal bodies or coiled bodies (CB), whose diameter measures between 0.2 µm and 2.0 µm depending on the cell type and species. When seen under an electron microscope, they resemble balls of tangled thread and are dense foci of distribution for the protein coilin. CBs are involved in a number of different roles relating to RNA processing, specifically small nucleolar RNA (snoRNA) and small nuclear RNA (snRNA) maturation, and histone mRNA modification.
Similar to Cajal bodies are Gemini of Cajal bodies, or gems, whose name is derived from the Gemini constellation in reference to their close "twin" relationship with CBs. Gems are similar in size and shape to CBs, and in fact are virtually indistinguishable under the microscope. Unlike CBs, gems do not contain small nuclear ribonucleoproteins (snRNPs), but do contain a protein called survival of motor neuron (SMN) whose function relates to snRNP biogenesis. Gems are believed to assist CBs in snRNP biogenesis, though it has also been suggested from microscopy evidence that CBs and gems are different manifestations of the same structure. Later ultrastructural studies have shown gems to be twins of Cajal bodies with the difference being in the coilin component; Cajal bodies are SMN positive and coilin positive, and gems are SMN positive and coilin negative.
PIKA domains, or polymorphic interphase karyosomal associations, were first described in microscopy studies in 1991. Their function remains unclear, though they were not thought to be associated with active DNA replication, transcription, or RNA processing. They have been found to often associate with discrete domains defined by dense localization of the transcription factor PTF, which promotes transcription of small nuclear RNA (snRNA).
Promyelocytic leukemia protein (PML-nuclear bodies) are spherical bodies found scattered throughout the nucleoplasm, measuring around 0.1–1.0 µm. They are known by a number of other names, including nuclear domain 10 (ND10), Kremer bodies, and PML oncogenic domains. PML-nuclear bodies are named after one of their major components, the promyelocytic leukemia protein (PML). They are often seen in the nucleus in association with Cajal bodies and cleavage bodies. Pml-/- mice, which are unable to create PML-nuclear bodies, develop normally without obvious ill effects, showing that PML-nuclear bodies are not required for most essential biological processes.
Speckles are subnuclear structures that are enriched in pre-messenger RNA splicing factors and are located in the interchromatin regions of the nucleoplasm of mammalian cells. At the fluorescence-microscope level they appear as irregular, punctate structures, which vary in size and shape, and when examined by electron microscopy they are seen as clusters of interchromatin granules. Speckles are dynamic structures, and both their protein and RNA-protein components can cycle continuously between speckles and other nuclear locations, including active transcription sites. Speckles can work with p53 as enhancers of gene activity to directly enhance the activity of certain genes. Moreover, speckle-associating and non-associating p53 gene targets are functionally distinct.
Studies on the composition, structure and behaviour of speckles have provided a model for understanding the functional compartmentalization of the nucleus and the organization of the gene-expression machinery splicing snRNPs and other splicing proteins necessary for pre-mRNA processing. Because of a cell's changing requirements, the composition and location of these bodies changes according to mRNA transcription and regulation via phosphorylation of specific proteins. The splicing speckles are also known as nuclear speckles (nuclear specks), splicing factor compartments (SF compartments), interchromatin granule clusters (IGCs), and B snurposomes. B snurposomes are found in the amphibian oocyte nuclei and in Drosophila melanogaster embryos. B snurposomes appear alone or attached to the Cajal bodies in the electron micrographs of the amphibian nuclei. IGCs function as storage sites for the splicing factors.
Discovered by Fox et al. in 2002, paraspeckles are irregularly shaped compartments in the interchromatin space of the nucleus. First documented in HeLa cells, where there are generally 10–30 per nucleus, paraspeckles are now known to also exist in all human primary cells, transformed cell lines, and tissue sections. Their name is derived from their distribution in the nucleus; the "para" is short for parallel and the "speckles" refers to the splicing speckles to which they are always in close proximity.
Paraspeckles sequester nuclear proteins and RNA and thus appear to function as a molecular sponge that is involved in the regulation of gene expression. Furthermore, paraspeckles are dynamic structures that are altered in response to changes in cellular metabolic activity. They are transcription dependent and in the absence of RNA Pol II transcription, the paraspeckle disappears and all of its associated protein components (PSP1, p54nrb, PSP2, CFI(m)68, and PSF) form a crescent shaped perinucleolar cap in the nucleolus. This phenomenon is demonstrated during the cell cycle. In the cell cycle, paraspeckles are present during interphase and during all of mitosis except for telophase. During telophase, when the two daughter nuclei are formed, there is no RNA Pol II transcription so the protein components instead form a perinucleolar cap.
Perichromatin fibrils are visible only under electron microscope. They are located next to the transcriptionally active chromatin and are hypothesized to be the sites of active pre-mRNA processing.
Clastosomes are small nuclear bodies (0.2–0.5 µm) described as having a thick ring-shape due to the peripheral capsule around these bodies. This name is derived from the Greek klastos, broken and soma, body. Clastosomes are not typically present in normal cells, making them hard to detect. They form under high proteolytic conditions within the nucleus and degrade once there is a decrease in activity or if cells are treated with proteasome inhibitors. The scarcity of clastosomes in cells indicates that they are not required for proteasome function. Osmotic stress has also been shown to cause the formation of clastosomes. These nuclear bodies contain catalytic and regulatory subunits of the proteasome and its substrates, indicating that clastosomes are sites for degrading proteins.
The nucleus provides a site for genetic transcription that is segregated from the location of translation in the cytoplasm, allowing levels of gene regulation that are not available to prokaryotes. The main function of the cell nucleus is to control gene expression and mediate the replication of DNA during the cell cycle.
The nuclear envelope allows control of the nuclear contents, and separates them from the rest of the cytoplasm where necessary. This is important for controlling processes on either side of the nuclear membrane: In most cases where a cytoplasmic process needs to be restricted, a key participant is removed to the nucleus, where it interacts with transcription factors to downregulate the production of certain enzymes in the pathway. This regulatory mechanism occurs in the case of glycolysis, a cellular pathway for breaking down glucose to produce energy. Hexokinase is an enzyme responsible for the first the step of glycolysis, forming glucose-6-phosphate from glucose. At high concentrations of fructose-6-phosphate, a molecule made later from glucose-6-phosphate, a regulator protein removes hexokinase to the nucleus, where it forms a transcriptional repressor complex with nuclear proteins to reduce the expression of genes involved in glycolysis.
In order to control which genes are being transcribed, the cell separates some transcription factor proteins responsible for regulating gene expression from physical access to the DNA until they are activated by other signaling pathways. This prevents even low levels of inappropriate gene expression. For example, in the case of NF-κB-controlled genes, which are involved in most inflammatory responses, transcription is induced in response to a signal pathway such as that initiated by the signaling molecule TNF-α, binds to a cell membrane receptor, resulting in the recruitment of signalling proteins, and eventually activating the transcription factor NF-κB. A nuclear localisation signal on the NF-κB protein allows it to be transported through the nuclear pore and into the nucleus, where it stimulates the transcription of the target genes.
The compartmentalization allows the cell to prevent translation of unspliced mRNA. Eukaryotic mRNA contains introns that must be removed before being translated to produce functional proteins. The splicing is done inside the nucleus before the mRNA can be accessed by ribosomes for translation. Without the nucleus, ribosomes would translate newly transcribed (unprocessed) mRNA, resulting in malformed and nonfunctional proteins.
The main function of the cell nucleus is to control gene expression and mediate the replication of DNA during the cell cycle. It has been found that replication happens in a localised way in the cell nucleus. In the S phase of interphase of the cell cycle; replication takes place. Contrary to the traditional view of moving replication forks along stagnant DNA, a concept of replication factories emerged, which means replication forks are concentrated towards some immobilised 'factory' regions through which the template DNA strands pass like conveyor belts.
Gene expression first involves transcription, in which DNA is used as a template to produce RNA. In the case of genes encoding proteins, that RNA produced from this process is messenger RNA (mRNA), which then needs to be translated by ribosomes to form a protein. As ribosomes are located outside the nucleus, mRNA produced needs to be exported.
Since the nucleus is the site of transcription, it also contains a variety of proteins that either directly mediate transcription or are involved in regulating the process. These proteins include helicases, which unwind the double-stranded DNA molecule to facilitate access to it, RNA polymerases, which bind to the DNA promoter to synthesize the growing RNA molecule, topoisomerases, which change the amount of supercoiling in DNA, helping it wind and unwind, as well as a large variety of transcription factors that regulate expression.
Newly synthesized mRNA molecules are known as primary transcripts or pre-mRNA. They must undergo post-transcriptional modification in the nucleus before being exported to the cytoplasm; mRNA that appears in the cytoplasm without these modifications is degraded rather than used for protein translation. The three main modifications are 5' capping, 3' polyadenylation, and RNA splicing. While in the nucleus, pre-mRNA is associated with a variety of proteins in complexes known as heterogeneous ribonucleoprotein particles (hnRNPs). Addition of the 5' cap occurs co-transcriptionally and is the first step in post-transcriptional modification. The 3' poly-adenine tail is only added after transcription is complete.
RNA splicing, carried out by a complex called the spliceosome, is the process by which introns, or regions of DNA that do not code for protein, are removed from the pre-mRNA and the remaining exons connected to re-form a single continuous molecule. This process normally occurs after 5' capping and 3' polyadenylation but can begin before synthesis is complete in transcripts with many exons. Many pre-mRNAs can be spliced in multiple ways to produce different mature mRNAs that encode different protein sequences. This process is known as alternative splicing, and allows production of a large variety of proteins from a limited amount of DNA.
The entry and exit of large molecules from the nucleus is tightly controlled by the nuclear pore complexes. Although small molecules can enter the nucleus without regulation, macromolecules such as RNA and proteins require association karyopherins called importins to enter the nucleus and exportins to exit. "Cargo" proteins that must be translocated from the cytoplasm to the nucleus contain short amino acid sequences known as nuclear localization signals, which are bound by importins, while those transported from the nucleus to the cytoplasm carry nuclear export signals bound by exportins. The ability of importins and exportins to transport their cargo is regulated by GTPases, enzymes that hydrolyze the molecule guanosine triphosphate (GTP) to release energy. The key GTPase in nuclear transport is Ran, which is bound to either GTP or GDP (guanosine diphosphate), depending on whether it is located in the nucleus or the cytoplasm. Whereas importins depend on RanGTP to dissociate from their cargo, exportins require RanGTP in order to bind to their cargo.
Nuclear import depends on the importin binding its cargo in the cytoplasm and carrying it through the nuclear pore into the nucleus. Inside the nucleus, RanGTP acts to separate the cargo from the importin, allowing the importin to exit the nucleus and be reused. Nuclear export is similar, as the exportin binds the cargo inside the nucleus in a process facilitated by RanGTP, exits through the nuclear pore, and separates from its cargo in the cytoplasm.
Specialized export proteins exist for translocation of mature mRNA and tRNA to the cytoplasm after post-transcriptional modification is complete. This quality-control mechanism is important due to these molecules' central role in protein translation. Mis-expression of a protein due to incomplete excision of exons or mis-incorporation of amino acids could have negative consequences for the cell; thus, incompletely modified RNA that reaches the cytoplasm is degraded rather than used in translation.
During its lifetime, a nucleus may be broken down or destroyed, either in the process of cell division or as a consequence of apoptosis (the process of programmed cell death). During these events, the structural components of the nucleus — the envelope and lamina — can be systematically degraded. In most cells, the disassembly of the nuclear envelope marks the end of the prophase of mitosis. However, this disassembly of the nucleus is not a universal feature of mitosis and does not occur in all cells. Some unicellular eukaryotes (e.g., yeasts) undergo so-called closed mitosis, in which the nuclear envelope remains intact. In closed mitosis, the daughter chromosomes migrate to opposite poles of the nucleus, which then divides in two. The cells of higher eukaryotes, however, usually undergo open mitosis, which is characterized by breakdown of the nuclear envelope. The daughter chromosomes then migrate to opposite poles of the mitotic spindle, and new nuclei reassemble around them.
At a certain point during the cell cycle in open mitosis, the cell divides to form two cells. In order for this process to be possible, each of the new daughter cells must have a full set of genes, a process requiring replication of the chromosomes as well as segregation of the separate sets. This occurs by the replicated chromosomes, the sister chromatids, attaching to microtubules, which in turn are attached to different centrosomes. The sister chromatids can then be pulled to separate locations in the cell. In many cells, the centrosome is located in the cytoplasm, outside the nucleus; the microtubules would be unable to attach to the chromatids in the presence of the nuclear envelope. Therefore, the early stages in the cell cycle, beginning in prophase and until around prometaphase, the nuclear membrane is dismantled. Likewise, during the same period, the nuclear lamina is also disassembled, a process regulated by phosphorylation of the lamins by protein kinases such as the CDC2 protein kinase. Towards the end of the cell cycle, the nuclear membrane is reformed, and around the same time, the nuclear lamina are reassembled by dephosphorylating the lamins.
However, in dinoflagellates, the nuclear envelope remains intact, the centrosomes are located in the cytoplasm, and the microtubules come in contact with chromosomes, whose centromeric regions are incorporated into the nuclear envelope (the so-called closed mitosis with extranuclear spindle). In many other protists (e.g., ciliates, sporozoans) and fungi, the centrosomes are intranuclear, and their nuclear envelope also does not disassemble during cell division.
Apoptosis is a controlled process in which the cell's structural components are destroyed, resulting in death of the cell. Changes associated with apoptosis directly affect the nucleus and its contents, for example, in the condensation of chromatin and the disintegration of the nuclear envelope and lamina. The destruction of the lamin networks is controlled by specialized apoptotic proteases called caspases, which cleave the lamin proteins and, thus, degrade the nucleus' structural integrity. Lamin cleavage is sometimes used as a laboratory indicator of caspase activity in assays for early apoptotic activity. Cells that express mutant caspase-resistant lamins are deficient in nuclear changes related to apoptosis, suggesting that lamins play a role in initiating the events that lead to apoptotic degradation of the nucleus. Inhibition of lamin assembly itself is an inducer of apoptosis.
The nuclear envelope acts as a barrier that prevents both DNA and RNA viruses from entering the nucleus. Some viruses require access to proteins inside the nucleus in order to replicate and/or assemble. DNA viruses, such as herpesvirus replicate and assemble in the cell nucleus, and exit by budding through the inner nuclear membrane. This process is accompanied by disassembly of the lamina on the nuclear face of the inner membrane.
Initially, it has been suspected that immunoglobulins in general and autoantibodies in particular do not enter the nucleus. Now there is a body of evidence that under pathological conditions (e.g. lupus erythematosus) IgG can enter the nucleus.
Most eukaryotic cell types usually have a single nucleus, but some have no nuclei, while others have several. This can result from normal development, as in the maturation of mammalian red blood cells, or from faulty cell division.
An anucleated cell contains no nucleus and is, therefore, incapable of dividing to produce daughter cells. The best-known anucleated cell is the mammalian red blood cell, or erythrocyte, which also lacks other organelles such as mitochondria, and serves primarily as a transport vessel to ferry oxygen from the lungs to the body's tissues. Erythrocytes mature through erythropoiesis in the bone marrow, where they lose their nuclei, organelles, and ribosomes. The nucleus is expelled during the process of differentiation from an erythroblast to a reticulocyte, which is the immediate precursor of the mature erythrocyte. The presence of mutagens may induce the release of some immature "micronucleated" erythrocytes into the bloodstream. Anucleated cells can also arise from flawed cell division in which one daughter lacks a nucleus and the other has two nuclei.
In flowering plants, this condition occurs in sieve tube elements.
Multinucleated cells contain multiple nuclei. Most acantharean species of protozoa and some fungi in mycorrhizae have naturally multinucleated cells. Other examples include the intestinal parasites in the genus Giardia, which have two nuclei per cell. Ciliates have two kinds of nuclei in a single cell, a somatic macronucleus and a germline micronucleus. In humans, skeletal muscle cells, also called myocytes and syncytium, become multinucleated during development; the resulting arrangement of nuclei near the periphery of the cells allows maximal intracellular space for myofibrils. Other multinucleate cells in the human are osteoclasts a type of bone cell. Multinucleated and binucleated cells can also be abnormal in humans; for example, cells arising from the fusion of monocytes and macrophages, known as giant multinucleated cells, sometimes accompany inflammation and are also implicated in tumor formation.
A number of dinoflagellates are known to have two nuclei. Unlike other multinucleated cells these nuclei contain two distinct lineages of DNA: one from the dinoflagellate and the other from a symbiotic diatom.
As the major defining characteristic of the eukaryotic cell, the nucleus's evolutionary origin has been the subject of much speculation. Four major hypotheses have been proposed to explain the existence of the nucleus, although none have yet earned widespread support.
The first model known as the "syntrophic model" proposes that a symbiotic relationship between the archaea and bacteria created the nucleus-containing eukaryotic cell. (Organisms of the Archaea and Bacteria domain have no cell nucleus.) It is hypothesized that the symbiosis originated when ancient archaea, similar to modern methanogenic archaea, invaded and lived within bacteria similar to modern myxobacteria, eventually forming the early nucleus. This theory is analogous to the accepted theory for the origin of eukaryotic mitochondria and chloroplasts, which are thought to have developed from a similar endosymbiotic relationship between proto-eukaryotes and aerobic bacteria. One possibility is that the nuclear membrane arose as a new membrane system following the origin of mitochondria in an archaebacterial host. The nuclear membrane may have served to protect the genome from damaging reactive oxygen species produced by the protomitochondria. The archaeal origin of the nucleus is supported by observations that archaea and eukarya have similar genes for certain proteins, including histones. Observations that myxobacteria are motile, can form multicellular complexes, and possess kinases and G proteins similar to eukarya, support a bacterial origin for the eukaryotic cell.
A second model proposes that proto-eukaryotic cells evolved from bacteria without an endosymbiotic stage. This model is based on the existence of modern Planctomycetota bacteria that possess a nuclear structure with primitive pores and other compartmentalized membrane structures. A similar proposal states that a eukaryote-like cell, the chronocyte, evolved first and phagocytosed archaea and bacteria to generate the nucleus and the eukaryotic cell.
The most controversial model, known as viral eukaryogenesis, posits that the membrane-bound nucleus, along with other eukaryotic features, originated from the infection of a prokaryote by a virus. The suggestion is based on similarities between eukaryotes and viruses such as linear DNA strands, mRNA capping, and tight binding to proteins (analogizing histones to viral envelopes). One version of the proposal suggests that the nucleus evolved in concert with phagocytosis to form an early cellular "predator". Another variant proposes that eukaryotes originated from early archaea infected by poxviruses, on the basis of observed similarity between the DNA polymerases in modern poxviruses and eukaryotes. It has been suggested that the unresolved question of the evolution of sex could be related to the viral eukaryogenesis hypothesis.
A more recent proposal, the exomembrane hypothesis, suggests that the nucleus instead originated from a single ancestral cell that evolved a second exterior cell membrane; the interior membrane enclosing the original cell then became the nuclear membrane and evolved increasingly elaborate pore structures for passage of internally synthesized cellular components such as ribosomal subunits.
The nucleus was the first organelle to be discovered. What is most likely the oldest preserved drawing dates back to the early microscopist Antonie van Leeuwenhoek (1632–1723). He observed a "lumen", the nucleus, in the red blood cells of salmon. Unlike mammalian red blood cells, those of other vertebrates still contain nuclei.
The nucleus was also described by Franz Bauer in 1804 and in more detail in 1831 by Scottish botanist Robert Brown in a talk at the Linnean Society of London. Brown was studying orchids under the microscope when he observed an opaque area, which he called the "areola" or "nucleus", in the cells of the flower's outer layer. He did not suggest a potential function.
In 1838, Matthias Schleiden proposed that the nucleus plays a role in generating cells, thus he introduced the name "cytoblast" ("cell builder"). He believed that he had observed new cells assembling around "cytoblasts". Franz Meyen was a strong opponent of this view, having already described cells multiplying by division and believing that many cells would have no nuclei. The idea that cells can be generated de novo, by the "cytoblast" or otherwise, contradicted work by Robert Remak (1852) and Rudolf Virchow (1855) who decisively propagated the new paradigm that cells are generated solely by cells ("Omnis cellula e cellula"). The function of the nucleus remained unclear.
Between 1877 and 1878, Oscar Hertwig published several studies on the fertilization of sea urchin eggs, showing that the nucleus of the sperm enters the oocyte and fuses with its nucleus. This was the first time it was suggested that an individual develops from a (single) nucleated cell. This was in contradiction to Ernst Haeckel's theory that the complete phylogeny of a species would be repeated during embryonic development, including generation of the first nucleated cell from a "monerula", a structureless mass of primordial protoplasm ("Urschleim"). Therefore, the necessity of the sperm nucleus for fertilization was discussed for quite some time. However, Hertwig confirmed his observation in other animal groups, including amphibians and molluscs. Eduard Strasburger produced the same results for plants in 1884. This paved the way to assign the nucleus an important role in heredity. In 1873, August Weismann postulated the equivalence of the maternal and paternal germ cells for heredity. The function of the nucleus as carrier of genetic information became clear only later, after mitosis was discovered and the Mendelian rules were rediscovered at the beginning of the 20th century; the chromosome theory of heredity was therefore developed. | [
{
"paragraph_id": 0,
"text": "The cell nucleus (from Latin nucleus or nuculeus 'kernel, seed'; PL: nuclei) is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long strands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating gene expression.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Because the nuclear envelope is impermeable to large molecules, nuclear pores are required to regulate nuclear transport of molecules across the envelope. The pores cross both nuclear membranes, providing a channel through which larger molecules must be actively transported by carrier proteins while allowing free movement of small molecules and ions. Movement of large molecules such as proteins and RNA through the pores is required for both gene expression and the maintenance of chromosomes. Although the interior of the nucleus does not contain any membrane-bound subcompartments, a number of nuclear bodies exist, made up of unique proteins, RNA molecules, and particular parts of the chromosomes. The best-known of these is the nucleolus, involved in the assembly of ribosomes.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The nucleus contains nearly all of the cell's DNA, surrounded by a network of fibrous intermediate filaments called the nuclear matrix, and is enveloped in a double membrane called the nuclear envelope. The nuclear envelope separates the fluid inside the nucleus, called the nucleoplasm, from the rest of the cell. The size of the nucleus is correlated to the size of the cell, and this ratio is reported across a range of cell types and species. In eukaryotes the nucleus in many cells typically occupies 10% of the cell volume. The nucleus is the largest organelle in animal cells. In human cells, the diameter of the nucleus is approximately six micrometres (µm).",
"title": "Structures"
},
{
"paragraph_id": 4,
"text": "The nuclear envelope consists of two membranes, an inner and an outer nuclear membrane, perforated by nuclear pores. Together, these membranes serve to separate the cell's genetic material from the rest of the cell contents, and allow the nucleus to maintain an environment distinct from the rest of the cell. Despite their close apposition around much of the nucleus, the two membranes differ substantially in shape and contents. The inner membrane surrounds the nuclear content, providing its defining edge. Embedded within the inner membrane, various proteins bind the intermediate filaments that give the nucleus its structure. The outer membrane encloses the inner membrane, and is continuous with the adjacent endoplasmic reticulum membrane. As part of the endoplasmic reticulum membrane, the outer nuclear membrane is studded with ribosomes that are actively translating proteins across membrane. The space between the two membranes is called the perinuclear space, and is continuous with the endoplasmic reticulum lumen.",
"title": "Structures"
},
{
"paragraph_id": 5,
"text": "In a mammalian nuclear envelope there are between 3000 and 4000 nuclear pore complexes (NPCs) perforating the envelope. Each NPC contains an eightfold-symmetric ring-shaped structure at a position where the inner and outer membranes fuse. The number of NPCs can vary considerably across cell types; small glial cells only have about a few hundred, with large Purkinje cells having around 20,000. The NPC provides selective transport of molecules between the nucleoplasm and the cytosol. The nuclear pore complex is composed of approximately thirty different proteins known as nucleoporins. The pores are about 60–80 million daltons in molecular weight and consist of around 50 (in yeast) to several hundred proteins (in vertebrates). The pores are 100 nm in total diameter; however, the gap through which molecules freely diffuse is only about 9 nm wide, due to the presence of regulatory systems within the center of the pore. This size selectively allows the passage of small water-soluble molecules while preventing larger molecules, such as nucleic acids and larger proteins, from inappropriately entering or exiting the nucleus. These large molecules must be actively transported into the nucleus instead. Attached to the ring is a structure called the nuclear basket that extends into the nucleoplasm, and a series of filamentous extensions that reach into the cytoplasm. Both structures serve to mediate binding to nuclear transport proteins.",
"title": "Structures"
},
{
"paragraph_id": 6,
"text": "Most proteins, ribosomal subunits, and some RNAs are transported through the pore complexes in a process mediated by a family of transport factors known as karyopherins. Those karyopherins that mediate movement into the nucleus are also called importins, whereas those that mediate movement out of the nucleus are called exportins. Most karyopherins interact directly with their cargo, although some use adaptor proteins. Steroid hormones such as cortisol and aldosterone, as well as other small lipid-soluble molecules involved in intercellular signaling, can diffuse through the cell membrane and into the cytoplasm, where they bind nuclear receptor proteins that are trafficked into the nucleus. There they serve as transcription factors when bound to their ligand; in the absence of a ligand, many such receptors function as histone deacetylases that repress gene expression.",
"title": "Structures"
},
{
"paragraph_id": 7,
"text": "In animal cells, two networks of intermediate filaments provide the nucleus with mechanical support: The nuclear lamina forms an organized meshwork on the internal face of the envelope, while less organized support is provided on the cytosolic face of the envelope. Both systems provide structural support for the nuclear envelope and anchoring sites for chromosomes and nuclear pores.",
"title": "Structures"
},
{
"paragraph_id": 8,
"text": "The nuclear lamina is composed mostly of lamin proteins. Like all proteins, lamins are synthesized in the cytoplasm and later transported to the nucleus interior, where they are assembled before being incorporated into the existing network of nuclear lamina. Lamins found on the cytosolic face of the membrane, such as emerin and nesprin, bind to the cytoskeleton to provide structural support. Lamins are also found inside the nucleoplasm where they form another regular structure, known as the nucleoplasmic veil, that is visible using fluorescence microscopy. The actual function of the veil is not clear, although it is excluded from the nucleolus and is present during interphase. Lamin structures that make up the veil, such as LEM3, bind chromatin and disrupting their structure inhibits transcription of protein-coding genes.",
"title": "Structures"
},
{
"paragraph_id": 9,
"text": "Like the components of other intermediate filaments, the lamin monomer contains an alpha-helical domain used by two monomers to coil around each other, forming a dimer structure called a coiled coil. Two of these dimer structures then join side by side, in an antiparallel arrangement, to form a tetramer called a protofilament. Eight of these protofilaments form a lateral arrangement that is twisted to form a ropelike filament. These filaments can be assembled or disassembled in a dynamic manner, meaning that changes in the length of the filament depend on the competing rates of filament addition and removal.",
"title": "Structures"
},
{
"paragraph_id": 10,
"text": "Mutations in lamin genes leading to defects in filament assembly cause a group of rare genetic disorders known as laminopathies. The most notable laminopathy is the family of diseases known as progeria, which causes the appearance of premature aging in those with the condition. The exact mechanism by which the associated biochemical changes give rise to the aged phenotype is not well understood.",
"title": "Structures"
},
{
"paragraph_id": 11,
"text": "The cell nucleus contains the majority of the cell's genetic material in the form of multiple linear DNA molecules organized into structures called chromosomes. Each human cell contains roughly two meters of DNA. During most of the cell cycle these are organized in a DNA-protein complex known as chromatin, and during cell division the chromatin can be seen to form the well-defined chromosomes familiar from a karyotype. A small fraction of the cell's genes are located instead in the mitochondria.",
"title": "Structures"
},
{
"paragraph_id": 12,
"text": "There are two types of chromatin. Euchromatin is the less compact DNA form, and contains genes that are frequently expressed by the cell. The other type, heterochromatin, is the more compact form, and contains DNA that is infrequently transcribed. This structure is further categorized into facultative heterochromatin, consisting of genes that are organized as heterochromatin only in certain cell types or at certain stages of development, and constitutive heterochromatin that consists of chromosome structural components such as telomeres and centromeres. During interphase the chromatin organizes itself into discrete individual patches, called chromosome territories. Active genes, which are generally found in the euchromatic region of the chromosome, tend to be located towards the chromosome's territory boundary.",
"title": "Structures"
},
{
"paragraph_id": 13,
"text": "Antibodies to certain types of chromatin organization, in particular, nucleosomes, have been associated with a number of autoimmune diseases, such as systemic lupus erythematosus. These are known as anti-nuclear antibodies (ANA) and have also been observed in concert with multiple sclerosis as part of general immune system dysfunction.",
"title": "Structures"
},
{
"paragraph_id": 14,
"text": "The nucleolus is the largest of the discrete densely stained, membraneless structures known as nuclear bodies found in the nucleus. It forms around tandem repeats of rDNA, DNA coding for ribosomal RNA (rRNA). These regions are called nucleolar organizer regions (NOR). The main roles of the nucleolus are to synthesize rRNA and assemble ribosomes. The structural cohesion of the nucleolus depends on its activity, as ribosomal assembly in the nucleolus results in the transient association of nucleolar components, facilitating further ribosomal assembly, and hence further association. This model is supported by observations that inactivation of rDNA results in intermingling of nucleolar structures.",
"title": "Structures"
},
{
"paragraph_id": 15,
"text": "In the first step of ribosome assembly, a protein called RNA polymerase I transcribes rDNA, which forms a large pre-rRNA precursor. This is cleaved into two large rRNA subunits – 5.8S, and 28S, and a small rRNA subunit 18S. The transcription, post-transcriptional processing, and assembly of rRNA occurs in the nucleolus, aided by small nucleolar RNA (snoRNA) molecules, some of which are derived from spliced introns from messenger RNAs encoding genes related to ribosomal function. The assembled ribosomal subunits are the largest structures passed through the nuclear pores.",
"title": "Structures"
},
{
"paragraph_id": 16,
"text": "When observed under the electron microscope, the nucleolus can be seen to consist of three distinguishable regions: the innermost fibrillar centers (FCs), surrounded by the dense fibrillar component (DFC) (that contains fibrillarin and nucleolin), which in turn is bordered by the granular component (GC) (that contains the protein nucleophosmin). Transcription of the rDNA occurs either in the FC or at the FC-DFC boundary, and, therefore, when rDNA transcription in the cell is increased, more FCs are detected. Most of the cleavage and modification of rRNAs occurs in the DFC, while the latter steps involving protein assembly onto the ribosomal subunits occur in the GC.",
"title": "Structures"
},
{
"paragraph_id": 17,
"text": "Besides the nucleolus, the nucleus contains a number of other nuclear bodies. These include Cajal bodies, gemini of Cajal bodies, polymorphic interphase karyosomal association (PIKA), promyelocytic leukaemia (PML) bodies, paraspeckles, and splicing speckles. Although little is known about a number of these domains, they are significant in that they show that the nucleoplasm is not a uniform mixture, but rather contains organized functional subdomains.",
"title": "Structures"
},
{
"paragraph_id": 18,
"text": "Other subnuclear structures appear as part of abnormal disease processes. For example, the presence of small intranuclear rods has been reported in some cases of nemaline myopathy. This condition typically results from mutations in actin, and the rods themselves consist of mutant actin as well as other cytoskeletal proteins.",
"title": "Structures"
},
{
"paragraph_id": 19,
"text": "A nucleus typically contains between one and ten compact structures called Cajal bodies or coiled bodies (CB), whose diameter measures between 0.2 µm and 2.0 µm depending on the cell type and species. When seen under an electron microscope, they resemble balls of tangled thread and are dense foci of distribution for the protein coilin. CBs are involved in a number of different roles relating to RNA processing, specifically small nucleolar RNA (snoRNA) and small nuclear RNA (snRNA) maturation, and histone mRNA modification.",
"title": "Structures"
},
{
"paragraph_id": 20,
"text": "Similar to Cajal bodies are Gemini of Cajal bodies, or gems, whose name is derived from the Gemini constellation in reference to their close \"twin\" relationship with CBs. Gems are similar in size and shape to CBs, and in fact are virtually indistinguishable under the microscope. Unlike CBs, gems do not contain small nuclear ribonucleoproteins (snRNPs), but do contain a protein called survival of motor neuron (SMN) whose function relates to snRNP biogenesis. Gems are believed to assist CBs in snRNP biogenesis, though it has also been suggested from microscopy evidence that CBs and gems are different manifestations of the same structure. Later ultrastructural studies have shown gems to be twins of Cajal bodies with the difference being in the coilin component; Cajal bodies are SMN positive and coilin positive, and gems are SMN positive and coilin negative.",
"title": "Structures"
},
{
"paragraph_id": 21,
"text": "PIKA domains, or polymorphic interphase karyosomal associations, were first described in microscopy studies in 1991. Their function remains unclear, though they were not thought to be associated with active DNA replication, transcription, or RNA processing. They have been found to often associate with discrete domains defined by dense localization of the transcription factor PTF, which promotes transcription of small nuclear RNA (snRNA).",
"title": "Structures"
},
{
"paragraph_id": 22,
"text": "Promyelocytic leukemia protein (PML-nuclear bodies) are spherical bodies found scattered throughout the nucleoplasm, measuring around 0.1–1.0 µm. They are known by a number of other names, including nuclear domain 10 (ND10), Kremer bodies, and PML oncogenic domains. PML-nuclear bodies are named after one of their major components, the promyelocytic leukemia protein (PML). They are often seen in the nucleus in association with Cajal bodies and cleavage bodies. Pml-/- mice, which are unable to create PML-nuclear bodies, develop normally without obvious ill effects, showing that PML-nuclear bodies are not required for most essential biological processes.",
"title": "Structures"
},
{
"paragraph_id": 23,
"text": "Speckles are subnuclear structures that are enriched in pre-messenger RNA splicing factors and are located in the interchromatin regions of the nucleoplasm of mammalian cells. At the fluorescence-microscope level they appear as irregular, punctate structures, which vary in size and shape, and when examined by electron microscopy they are seen as clusters of interchromatin granules. Speckles are dynamic structures, and both their protein and RNA-protein components can cycle continuously between speckles and other nuclear locations, including active transcription sites. Speckles can work with p53 as enhancers of gene activity to directly enhance the activity of certain genes. Moreover, speckle-associating and non-associating p53 gene targets are functionally distinct.",
"title": "Structures"
},
{
"paragraph_id": 24,
"text": "Studies on the composition, structure and behaviour of speckles have provided a model for understanding the functional compartmentalization of the nucleus and the organization of the gene-expression machinery splicing snRNPs and other splicing proteins necessary for pre-mRNA processing. Because of a cell's changing requirements, the composition and location of these bodies changes according to mRNA transcription and regulation via phosphorylation of specific proteins. The splicing speckles are also known as nuclear speckles (nuclear specks), splicing factor compartments (SF compartments), interchromatin granule clusters (IGCs), and B snurposomes. B snurposomes are found in the amphibian oocyte nuclei and in Drosophila melanogaster embryos. B snurposomes appear alone or attached to the Cajal bodies in the electron micrographs of the amphibian nuclei. IGCs function as storage sites for the splicing factors.",
"title": "Structures"
},
{
"paragraph_id": 25,
"text": "Discovered by Fox et al. in 2002, paraspeckles are irregularly shaped compartments in the interchromatin space of the nucleus. First documented in HeLa cells, where there are generally 10–30 per nucleus, paraspeckles are now known to also exist in all human primary cells, transformed cell lines, and tissue sections. Their name is derived from their distribution in the nucleus; the \"para\" is short for parallel and the \"speckles\" refers to the splicing speckles to which they are always in close proximity.",
"title": "Structures"
},
{
"paragraph_id": 26,
"text": "Paraspeckles sequester nuclear proteins and RNA and thus appear to function as a molecular sponge that is involved in the regulation of gene expression. Furthermore, paraspeckles are dynamic structures that are altered in response to changes in cellular metabolic activity. They are transcription dependent and in the absence of RNA Pol II transcription, the paraspeckle disappears and all of its associated protein components (PSP1, p54nrb, PSP2, CFI(m)68, and PSF) form a crescent shaped perinucleolar cap in the nucleolus. This phenomenon is demonstrated during the cell cycle. In the cell cycle, paraspeckles are present during interphase and during all of mitosis except for telophase. During telophase, when the two daughter nuclei are formed, there is no RNA Pol II transcription so the protein components instead form a perinucleolar cap.",
"title": "Structures"
},
{
"paragraph_id": 27,
"text": "Perichromatin fibrils are visible only under electron microscope. They are located next to the transcriptionally active chromatin and are hypothesized to be the sites of active pre-mRNA processing.",
"title": "Structures"
},
{
"paragraph_id": 28,
"text": "Clastosomes are small nuclear bodies (0.2–0.5 µm) described as having a thick ring-shape due to the peripheral capsule around these bodies. This name is derived from the Greek klastos, broken and soma, body. Clastosomes are not typically present in normal cells, making them hard to detect. They form under high proteolytic conditions within the nucleus and degrade once there is a decrease in activity or if cells are treated with proteasome inhibitors. The scarcity of clastosomes in cells indicates that they are not required for proteasome function. Osmotic stress has also been shown to cause the formation of clastosomes. These nuclear bodies contain catalytic and regulatory subunits of the proteasome and its substrates, indicating that clastosomes are sites for degrading proteins.",
"title": "Structures"
},
{
"paragraph_id": 29,
"text": "The nucleus provides a site for genetic transcription that is segregated from the location of translation in the cytoplasm, allowing levels of gene regulation that are not available to prokaryotes. The main function of the cell nucleus is to control gene expression and mediate the replication of DNA during the cell cycle.",
"title": "Function"
},
{
"paragraph_id": 30,
"text": "The nuclear envelope allows control of the nuclear contents, and separates them from the rest of the cytoplasm where necessary. This is important for controlling processes on either side of the nuclear membrane: In most cases where a cytoplasmic process needs to be restricted, a key participant is removed to the nucleus, where it interacts with transcription factors to downregulate the production of certain enzymes in the pathway. This regulatory mechanism occurs in the case of glycolysis, a cellular pathway for breaking down glucose to produce energy. Hexokinase is an enzyme responsible for the first the step of glycolysis, forming glucose-6-phosphate from glucose. At high concentrations of fructose-6-phosphate, a molecule made later from glucose-6-phosphate, a regulator protein removes hexokinase to the nucleus, where it forms a transcriptional repressor complex with nuclear proteins to reduce the expression of genes involved in glycolysis.",
"title": "Function"
},
{
"paragraph_id": 31,
"text": "In order to control which genes are being transcribed, the cell separates some transcription factor proteins responsible for regulating gene expression from physical access to the DNA until they are activated by other signaling pathways. This prevents even low levels of inappropriate gene expression. For example, in the case of NF-κB-controlled genes, which are involved in most inflammatory responses, transcription is induced in response to a signal pathway such as that initiated by the signaling molecule TNF-α, binds to a cell membrane receptor, resulting in the recruitment of signalling proteins, and eventually activating the transcription factor NF-κB. A nuclear localisation signal on the NF-κB protein allows it to be transported through the nuclear pore and into the nucleus, where it stimulates the transcription of the target genes.",
"title": "Function"
},
{
"paragraph_id": 32,
"text": "The compartmentalization allows the cell to prevent translation of unspliced mRNA. Eukaryotic mRNA contains introns that must be removed before being translated to produce functional proteins. The splicing is done inside the nucleus before the mRNA can be accessed by ribosomes for translation. Without the nucleus, ribosomes would translate newly transcribed (unprocessed) mRNA, resulting in malformed and nonfunctional proteins.",
"title": "Function"
},
{
"paragraph_id": 33,
"text": "The main function of the cell nucleus is to control gene expression and mediate the replication of DNA during the cell cycle. It has been found that replication happens in a localised way in the cell nucleus. In the S phase of interphase of the cell cycle; replication takes place. Contrary to the traditional view of moving replication forks along stagnant DNA, a concept of replication factories emerged, which means replication forks are concentrated towards some immobilised 'factory' regions through which the template DNA strands pass like conveyor belts.",
"title": "Function"
},
{
"paragraph_id": 34,
"text": "Gene expression first involves transcription, in which DNA is used as a template to produce RNA. In the case of genes encoding proteins, that RNA produced from this process is messenger RNA (mRNA), which then needs to be translated by ribosomes to form a protein. As ribosomes are located outside the nucleus, mRNA produced needs to be exported.",
"title": "Function"
},
{
"paragraph_id": 35,
"text": "Since the nucleus is the site of transcription, it also contains a variety of proteins that either directly mediate transcription or are involved in regulating the process. These proteins include helicases, which unwind the double-stranded DNA molecule to facilitate access to it, RNA polymerases, which bind to the DNA promoter to synthesize the growing RNA molecule, topoisomerases, which change the amount of supercoiling in DNA, helping it wind and unwind, as well as a large variety of transcription factors that regulate expression.",
"title": "Function"
},
{
"paragraph_id": 36,
"text": "Newly synthesized mRNA molecules are known as primary transcripts or pre-mRNA. They must undergo post-transcriptional modification in the nucleus before being exported to the cytoplasm; mRNA that appears in the cytoplasm without these modifications is degraded rather than used for protein translation. The three main modifications are 5' capping, 3' polyadenylation, and RNA splicing. While in the nucleus, pre-mRNA is associated with a variety of proteins in complexes known as heterogeneous ribonucleoprotein particles (hnRNPs). Addition of the 5' cap occurs co-transcriptionally and is the first step in post-transcriptional modification. The 3' poly-adenine tail is only added after transcription is complete.",
"title": "Function"
},
{
"paragraph_id": 37,
"text": "RNA splicing, carried out by a complex called the spliceosome, is the process by which introns, or regions of DNA that do not code for protein, are removed from the pre-mRNA and the remaining exons connected to re-form a single continuous molecule. This process normally occurs after 5' capping and 3' polyadenylation but can begin before synthesis is complete in transcripts with many exons. Many pre-mRNAs can be spliced in multiple ways to produce different mature mRNAs that encode different protein sequences. This process is known as alternative splicing, and allows production of a large variety of proteins from a limited amount of DNA.",
"title": "Function"
},
{
"paragraph_id": 38,
"text": "The entry and exit of large molecules from the nucleus is tightly controlled by the nuclear pore complexes. Although small molecules can enter the nucleus without regulation, macromolecules such as RNA and proteins require association karyopherins called importins to enter the nucleus and exportins to exit. \"Cargo\" proteins that must be translocated from the cytoplasm to the nucleus contain short amino acid sequences known as nuclear localization signals, which are bound by importins, while those transported from the nucleus to the cytoplasm carry nuclear export signals bound by exportins. The ability of importins and exportins to transport their cargo is regulated by GTPases, enzymes that hydrolyze the molecule guanosine triphosphate (GTP) to release energy. The key GTPase in nuclear transport is Ran, which is bound to either GTP or GDP (guanosine diphosphate), depending on whether it is located in the nucleus or the cytoplasm. Whereas importins depend on RanGTP to dissociate from their cargo, exportins require RanGTP in order to bind to their cargo.",
"title": "Dynamics and regulation"
},
{
"paragraph_id": 39,
"text": "Nuclear import depends on the importin binding its cargo in the cytoplasm and carrying it through the nuclear pore into the nucleus. Inside the nucleus, RanGTP acts to separate the cargo from the importin, allowing the importin to exit the nucleus and be reused. Nuclear export is similar, as the exportin binds the cargo inside the nucleus in a process facilitated by RanGTP, exits through the nuclear pore, and separates from its cargo in the cytoplasm.",
"title": "Dynamics and regulation"
},
{
"paragraph_id": 40,
"text": "Specialized export proteins exist for translocation of mature mRNA and tRNA to the cytoplasm after post-transcriptional modification is complete. This quality-control mechanism is important due to these molecules' central role in protein translation. Mis-expression of a protein due to incomplete excision of exons or mis-incorporation of amino acids could have negative consequences for the cell; thus, incompletely modified RNA that reaches the cytoplasm is degraded rather than used in translation.",
"title": "Dynamics and regulation"
},
{
"paragraph_id": 41,
"text": "During its lifetime, a nucleus may be broken down or destroyed, either in the process of cell division or as a consequence of apoptosis (the process of programmed cell death). During these events, the structural components of the nucleus — the envelope and lamina — can be systematically degraded. In most cells, the disassembly of the nuclear envelope marks the end of the prophase of mitosis. However, this disassembly of the nucleus is not a universal feature of mitosis and does not occur in all cells. Some unicellular eukaryotes (e.g., yeasts) undergo so-called closed mitosis, in which the nuclear envelope remains intact. In closed mitosis, the daughter chromosomes migrate to opposite poles of the nucleus, which then divides in two. The cells of higher eukaryotes, however, usually undergo open mitosis, which is characterized by breakdown of the nuclear envelope. The daughter chromosomes then migrate to opposite poles of the mitotic spindle, and new nuclei reassemble around them.",
"title": "Dynamics and regulation"
},
{
"paragraph_id": 42,
"text": "At a certain point during the cell cycle in open mitosis, the cell divides to form two cells. In order for this process to be possible, each of the new daughter cells must have a full set of genes, a process requiring replication of the chromosomes as well as segregation of the separate sets. This occurs by the replicated chromosomes, the sister chromatids, attaching to microtubules, which in turn are attached to different centrosomes. The sister chromatids can then be pulled to separate locations in the cell. In many cells, the centrosome is located in the cytoplasm, outside the nucleus; the microtubules would be unable to attach to the chromatids in the presence of the nuclear envelope. Therefore, the early stages in the cell cycle, beginning in prophase and until around prometaphase, the nuclear membrane is dismantled. Likewise, during the same period, the nuclear lamina is also disassembled, a process regulated by phosphorylation of the lamins by protein kinases such as the CDC2 protein kinase. Towards the end of the cell cycle, the nuclear membrane is reformed, and around the same time, the nuclear lamina are reassembled by dephosphorylating the lamins.",
"title": "Dynamics and regulation"
},
{
"paragraph_id": 43,
"text": "However, in dinoflagellates, the nuclear envelope remains intact, the centrosomes are located in the cytoplasm, and the microtubules come in contact with chromosomes, whose centromeric regions are incorporated into the nuclear envelope (the so-called closed mitosis with extranuclear spindle). In many other protists (e.g., ciliates, sporozoans) and fungi, the centrosomes are intranuclear, and their nuclear envelope also does not disassemble during cell division.",
"title": "Dynamics and regulation"
},
{
"paragraph_id": 44,
"text": "Apoptosis is a controlled process in which the cell's structural components are destroyed, resulting in death of the cell. Changes associated with apoptosis directly affect the nucleus and its contents, for example, in the condensation of chromatin and the disintegration of the nuclear envelope and lamina. The destruction of the lamin networks is controlled by specialized apoptotic proteases called caspases, which cleave the lamin proteins and, thus, degrade the nucleus' structural integrity. Lamin cleavage is sometimes used as a laboratory indicator of caspase activity in assays for early apoptotic activity. Cells that express mutant caspase-resistant lamins are deficient in nuclear changes related to apoptosis, suggesting that lamins play a role in initiating the events that lead to apoptotic degradation of the nucleus. Inhibition of lamin assembly itself is an inducer of apoptosis.",
"title": "Dynamics and regulation"
},
{
"paragraph_id": 45,
"text": "The nuclear envelope acts as a barrier that prevents both DNA and RNA viruses from entering the nucleus. Some viruses require access to proteins inside the nucleus in order to replicate and/or assemble. DNA viruses, such as herpesvirus replicate and assemble in the cell nucleus, and exit by budding through the inner nuclear membrane. This process is accompanied by disassembly of the lamina on the nuclear face of the inner membrane.",
"title": "Dynamics and regulation"
},
{
"paragraph_id": 46,
"text": "Initially, it has been suspected that immunoglobulins in general and autoantibodies in particular do not enter the nucleus. Now there is a body of evidence that under pathological conditions (e.g. lupus erythematosus) IgG can enter the nucleus.",
"title": "Dynamics and regulation"
},
{
"paragraph_id": 47,
"text": "Most eukaryotic cell types usually have a single nucleus, but some have no nuclei, while others have several. This can result from normal development, as in the maturation of mammalian red blood cells, or from faulty cell division.",
"title": "Nuclei per cell"
},
{
"paragraph_id": 48,
"text": "An anucleated cell contains no nucleus and is, therefore, incapable of dividing to produce daughter cells. The best-known anucleated cell is the mammalian red blood cell, or erythrocyte, which also lacks other organelles such as mitochondria, and serves primarily as a transport vessel to ferry oxygen from the lungs to the body's tissues. Erythrocytes mature through erythropoiesis in the bone marrow, where they lose their nuclei, organelles, and ribosomes. The nucleus is expelled during the process of differentiation from an erythroblast to a reticulocyte, which is the immediate precursor of the mature erythrocyte. The presence of mutagens may induce the release of some immature \"micronucleated\" erythrocytes into the bloodstream. Anucleated cells can also arise from flawed cell division in which one daughter lacks a nucleus and the other has two nuclei.",
"title": "Nuclei per cell"
},
{
"paragraph_id": 49,
"text": "In flowering plants, this condition occurs in sieve tube elements.",
"title": "Nuclei per cell"
},
{
"paragraph_id": 50,
"text": "Multinucleated cells contain multiple nuclei. Most acantharean species of protozoa and some fungi in mycorrhizae have naturally multinucleated cells. Other examples include the intestinal parasites in the genus Giardia, which have two nuclei per cell. Ciliates have two kinds of nuclei in a single cell, a somatic macronucleus and a germline micronucleus. In humans, skeletal muscle cells, also called myocytes and syncytium, become multinucleated during development; the resulting arrangement of nuclei near the periphery of the cells allows maximal intracellular space for myofibrils. Other multinucleate cells in the human are osteoclasts a type of bone cell. Multinucleated and binucleated cells can also be abnormal in humans; for example, cells arising from the fusion of monocytes and macrophages, known as giant multinucleated cells, sometimes accompany inflammation and are also implicated in tumor formation.",
"title": "Nuclei per cell"
},
{
"paragraph_id": 51,
"text": "A number of dinoflagellates are known to have two nuclei. Unlike other multinucleated cells these nuclei contain two distinct lineages of DNA: one from the dinoflagellate and the other from a symbiotic diatom.",
"title": "Nuclei per cell"
},
{
"paragraph_id": 52,
"text": "As the major defining characteristic of the eukaryotic cell, the nucleus's evolutionary origin has been the subject of much speculation. Four major hypotheses have been proposed to explain the existence of the nucleus, although none have yet earned widespread support.",
"title": "Evolution"
},
{
"paragraph_id": 53,
"text": "The first model known as the \"syntrophic model\" proposes that a symbiotic relationship between the archaea and bacteria created the nucleus-containing eukaryotic cell. (Organisms of the Archaea and Bacteria domain have no cell nucleus.) It is hypothesized that the symbiosis originated when ancient archaea, similar to modern methanogenic archaea, invaded and lived within bacteria similar to modern myxobacteria, eventually forming the early nucleus. This theory is analogous to the accepted theory for the origin of eukaryotic mitochondria and chloroplasts, which are thought to have developed from a similar endosymbiotic relationship between proto-eukaryotes and aerobic bacteria. One possibility is that the nuclear membrane arose as a new membrane system following the origin of mitochondria in an archaebacterial host. The nuclear membrane may have served to protect the genome from damaging reactive oxygen species produced by the protomitochondria. The archaeal origin of the nucleus is supported by observations that archaea and eukarya have similar genes for certain proteins, including histones. Observations that myxobacteria are motile, can form multicellular complexes, and possess kinases and G proteins similar to eukarya, support a bacterial origin for the eukaryotic cell.",
"title": "Evolution"
},
{
"paragraph_id": 54,
"text": "A second model proposes that proto-eukaryotic cells evolved from bacteria without an endosymbiotic stage. This model is based on the existence of modern Planctomycetota bacteria that possess a nuclear structure with primitive pores and other compartmentalized membrane structures. A similar proposal states that a eukaryote-like cell, the chronocyte, evolved first and phagocytosed archaea and bacteria to generate the nucleus and the eukaryotic cell.",
"title": "Evolution"
},
{
"paragraph_id": 55,
"text": "The most controversial model, known as viral eukaryogenesis, posits that the membrane-bound nucleus, along with other eukaryotic features, originated from the infection of a prokaryote by a virus. The suggestion is based on similarities between eukaryotes and viruses such as linear DNA strands, mRNA capping, and tight binding to proteins (analogizing histones to viral envelopes). One version of the proposal suggests that the nucleus evolved in concert with phagocytosis to form an early cellular \"predator\". Another variant proposes that eukaryotes originated from early archaea infected by poxviruses, on the basis of observed similarity between the DNA polymerases in modern poxviruses and eukaryotes. It has been suggested that the unresolved question of the evolution of sex could be related to the viral eukaryogenesis hypothesis.",
"title": "Evolution"
},
{
"paragraph_id": 56,
"text": "A more recent proposal, the exomembrane hypothesis, suggests that the nucleus instead originated from a single ancestral cell that evolved a second exterior cell membrane; the interior membrane enclosing the original cell then became the nuclear membrane and evolved increasingly elaborate pore structures for passage of internally synthesized cellular components such as ribosomal subunits.",
"title": "Evolution"
},
{
"paragraph_id": 57,
"text": "The nucleus was the first organelle to be discovered. What is most likely the oldest preserved drawing dates back to the early microscopist Antonie van Leeuwenhoek (1632–1723). He observed a \"lumen\", the nucleus, in the red blood cells of salmon. Unlike mammalian red blood cells, those of other vertebrates still contain nuclei.",
"title": "History"
},
{
"paragraph_id": 58,
"text": "The nucleus was also described by Franz Bauer in 1804 and in more detail in 1831 by Scottish botanist Robert Brown in a talk at the Linnean Society of London. Brown was studying orchids under the microscope when he observed an opaque area, which he called the \"areola\" or \"nucleus\", in the cells of the flower's outer layer. He did not suggest a potential function.",
"title": "History"
},
{
"paragraph_id": 59,
"text": "In 1838, Matthias Schleiden proposed that the nucleus plays a role in generating cells, thus he introduced the name \"cytoblast\" (\"cell builder\"). He believed that he had observed new cells assembling around \"cytoblasts\". Franz Meyen was a strong opponent of this view, having already described cells multiplying by division and believing that many cells would have no nuclei. The idea that cells can be generated de novo, by the \"cytoblast\" or otherwise, contradicted work by Robert Remak (1852) and Rudolf Virchow (1855) who decisively propagated the new paradigm that cells are generated solely by cells (\"Omnis cellula e cellula\"). The function of the nucleus remained unclear.",
"title": "History"
},
{
"paragraph_id": 60,
"text": "Between 1877 and 1878, Oscar Hertwig published several studies on the fertilization of sea urchin eggs, showing that the nucleus of the sperm enters the oocyte and fuses with its nucleus. This was the first time it was suggested that an individual develops from a (single) nucleated cell. This was in contradiction to Ernst Haeckel's theory that the complete phylogeny of a species would be repeated during embryonic development, including generation of the first nucleated cell from a \"monerula\", a structureless mass of primordial protoplasm (\"Urschleim\"). Therefore, the necessity of the sperm nucleus for fertilization was discussed for quite some time. However, Hertwig confirmed his observation in other animal groups, including amphibians and molluscs. Eduard Strasburger produced the same results for plants in 1884. This paved the way to assign the nucleus an important role in heredity. In 1873, August Weismann postulated the equivalence of the maternal and paternal germ cells for heredity. The function of the nucleus as carrier of genetic information became clear only later, after mitosis was discovered and the Mendelian rules were rediscovered at the beginning of the 20th century; the chromosome theory of heredity was therefore developed.",
"title": "History"
}
] | The cell nucleus is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm; and the nuclear matrix, a network within the nucleus that adds mechanical support. The cell nucleus contains nearly all of the cell's genome. Nuclear DNA is often organized into multiple chromosomes – long strands of DNA dotted with various proteins, such as histones, that protect and organize the DNA. The genes within these chromosomes are structured in such a way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating gene expression. Because the nuclear envelope is impermeable to large molecules, nuclear pores are required to regulate nuclear transport of molecules across the envelope. The pores cross both nuclear membranes, providing a channel through which larger molecules must be actively transported by carrier proteins while allowing free movement of small molecules and ions. Movement of large molecules such as proteins and RNA through the pores is required for both gene expression and the maintenance of chromosomes. Although the interior of the nucleus does not contain any membrane-bound subcompartments, a number of nuclear bodies exist, made up of unique proteins, RNA molecules, and particular parts of the chromosomes. The best-known of these is the nucleolus, involved in the assembly of ribosomes. | 2001-08-31T00:30:16Z | 2023-08-20T01:09:38Z | [
"Template:Nucleus",
"Template:Plural form",
"Template:Rp",
"Template:Nowrap",
"Template:Refend",
"Template:Webarchive",
"Template:Authority control",
"Template:Clear",
"Template:Lang",
"Template:Refbegin",
"Template:Library resources box",
"Template:Main",
"Template:See also",
"Template:Reflist",
"Template:Cite web",
"Template:Short description",
"Template:Pp-vandalism",
"Template:Use dmy dates",
"Template:Organelle diagram",
"Template:Organelles",
"Template:Cite book",
"Template:Commons category",
"Template:Etymology",
"Template:Further",
"Template:Anchor",
"Template:Cite journal"
] | https://en.wikipedia.org/wiki/Cell_nucleus |
6,237 | Christmas | Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25 as a religious and cultural celebration among billions of people around the world. A feast central to the liturgical year in Christianity, it follows the season of Advent (which begins four Sundays before) or the Nativity Fast, and initiates the season of Christmastide, which historically in the West lasts twelve days and culminates on Twelfth Night. Christmas Day is a public holiday in many countries, is celebrated religiously by a majority of Christians, as well as culturally by many non-Christians, and forms an integral part of the holiday season surrounding it.
The traditional Christmas narrative recounted in the New Testament, known as the Nativity of Jesus, says that Jesus was born in Bethlehem, in accordance with messianic prophecies. When Joseph and Mary arrived in the city, the inn had no room, and so they were offered a stable where the Christ Child was soon born, with angels proclaiming this news to shepherds, who then spread the word.
There are different hypotheses regarding the date of Jesus's birth, and in the early fourth century, the church fixed the date as December 25. This corresponds to the traditional date of the winter solstice on the Roman calendar. It is exactly nine months after Annunciation on March 25, also the date of the spring equinox. Most Christians celebrate on December 25 in the Gregorian calendar, which has been adopted almost universally in the civil calendars used in countries throughout the world. However, part of the Eastern Christian Churches celebrate Christmas on December 25 of the older Julian calendar, which currently corresponds to January 7 in the Gregorian calendar. For Christians, believing that God came into the world in the form of man to atone for the sins of humanity rather than knowing Jesus's exact birth date is considered to be the primary purpose of celebrating Christmas.
The customs associated with Christmas in various countries have a mix of pre-Christian, Christian, and secular themes and origins. Popular holiday traditions include gift giving; completing an Advent calendar or Advent wreath; Christmas music and caroling; watching Christmas movies; viewing a Nativity play; an exchange of Christmas cards; attending church services; a special meal; and displaying various Christmas decorations, including Christmas trees, Christmas lights, nativity scenes, garlands, wreaths, mistletoe, and holly. Additionally, several related and often interchangeable figures, known as Santa Claus, Father Christmas, Saint Nicholas, and Christkind, are associated with bringing gifts to children during the Christmas season and have their own body of traditions and lore. Because gift-giving and many other aspects of the Christmas festival involve heightened economic activity, the holiday has become a significant event and a key sales period for retailers and businesses. Over the past few centuries, Christmas has had a steadily growing economic effect in many regions of the world.
The English word Christmas is a shortened form of 'Christ's Mass'. The word is recorded as Crīstesmæsse in 1038 and Cristes-messe in 1131. Crīst (genitive Crīstes) is from the Greek Χριστός (Khrīstos, 'Christ'), a translation of the Hebrew מָשִׁיחַ (Māšîaḥ, 'Messiah'), meaning 'anointed'; and mæsse is from the Latin missa, the celebration of the Eucharist.
The form Christenmas was also used during some periods, but is now considered archaic and dialectal. The term derives from Middle English Cristenmasse, meaning 'Christian mass'. Xmas is an abbreviation of Christmas found particularly in print, based on the initial letter chi (Χ) in the Greek Χριστός, although some style guides discourage its use. This abbreviation has precedent in Middle English Χρ̄es masse (where Χρ̄ is another abbreviation of the Greek word).
The holiday has had various other English names throughout its history. The Anglo-Saxons referred to the feast as "midwinter", or, more rarely, as Nātiuiteð (from the Latin nātīvitās below). Nativity, meaning 'birth', is from the Latin nātīvitās. In Old English, Gēola ('Yule') referred to the period corresponding to December and January, which was eventually equated with Christian Christmas. 'Noel' (also 'Nowel' or 'Nowell', as in "The First Nowell") entered English in the late 14th century and is from the Old French noël or naël, itself ultimately from the Latin nātālis (diēs) meaning 'birth (day)'.
Koleda is the traditional Slavic name for Christmas and the period from Christmas to Epiphany or, more generally, to Slavic Christmas-related rituals, some dating to pre-Christian times.
The gospels of Luke and Matthew describe Jesus as being born in Bethlehem to the Virgin Mary. In the Gospel of Luke, Joseph and Mary travel from Nazareth to Bethlehem in order to be counted for a census, and Jesus is born there and placed in a manger. Angels proclaim him a savior for all people, and three shepherds come to adore him. In the Gospel of Matthew, by contrast, three magi follow a star to Bethlehem to bring gifts to Jesus, born the king of the Jews. King Herod orders the massacre of all the boys less than two years old in Bethlehem, but the family flees to Egypt and later returns to Nazareth.
In the 2nd century, the "earliest church records" indicate that "Christians were remembering and celebrating the birth of the Lord", an "observance [that] sprang up organically from the authentic devotion of ordinary believers"; although "they did not agree upon a set date". The earliest evidence of Christ's birth being marked on December 25 is a sentence in the Chronograph of 354. Liturgical historians generally agree that this part of the text was written in Rome in AD 336. Though Christmas did not appear on the lists of festivals given by the early Christian writers Irenaeus and Tertullian, the early Church Fathers John Chrysostom, Augustine of Hippo, and Jerome attested to December 25 as the date of Christmas toward the end of the fourth century. December 25 was the traditional date of the winter solstice in the Roman Empire, where most Christians lived, and the Roman festival Dies Natalis Solis Invicti (birthday of Sol Invictus, the 'Invincible Sun') had been held on this date since 274 AD.
In the East, the birth of Jesus was celebrated in connection with the Epiphany on January 6. This holiday was not primarily about Christ's birth, but rather his baptism. Christmas was promoted in the East as part of the revival of Orthodox Christianity that followed the death of the pro-Arian Emperor Valens at the Battle of Adrianople in 378. The feast was introduced in Constantinople in 379, in Antioch by John Chrysostom towards the end of the fourth century, probably in 388, and in Alexandria in the following century. The Georgian Iadgari demonstrates that Christmas was celebrated in Jerusalem by the sixth century.
In the Early Middle Ages, Christmas Day was overshadowed by Epiphany, which in western Christianity focused on the visit of the magi. However, the medieval calendar was dominated by Christmas-related holidays. The forty days before Christmas became the "forty days of St. Martin" (which began on November 11, the feast of St. Martin of Tours), now known as Advent. In Italy, former Saturnalian traditions were attached to Advent. Around the 12th century, these traditions transferred again to the Twelve Days of Christmas (December 25–January 5); a time that appears in the liturgical calendars as Christmastide or Twelve Holy Days.
In 567, the Council of Tours put in place the season of Christmastide, proclaiming "the twelve days from Christmas to Epiphany as a sacred and festive season, and established the duty of Advent fasting in preparation for the feast." This was done in order to solve the "administrative problem for the Roman Empire as it tried to coordinate the solar Julian calendar with the lunar calendars of its provinces in the east."
The prominence of Christmas Day increased gradually after Charlemagne was crowned Emperor on Christmas Day in 800. King Edmund the Martyr was anointed on Christmas in 855 and King William I of England was crowned on Christmas Day 1066.
By the High Middle Ages, the holiday had become so prominent that chroniclers routinely noted where various magnates celebrated Christmas. King Richard II of England hosted a Christmas feast in 1377 at which 28 oxen and 300 sheep were eaten. The Yule boar was a common feature of medieval Christmas feasts. Caroling also became popular, and was originally performed by a group of dancers who sang. The group was composed of a lead singer and a ring of dancers that provided the chorus. Various writers of the time condemned caroling as lewd, indicating that the unruly traditions of Saturnalia and Yule may have continued in this form. "Misrule"—drunkenness, promiscuity, gambling—was also an important aspect of the festival. In England, gifts were exchanged on New Year's Day, and there was special Christmas ale.
Christmas during the Middle Ages was a public festival that incorporated ivy, holly, and other evergreens. Christmas gift-giving during the Middle Ages was usually between people with legal relationships, such as tenant and landlord. The annual indulgence in eating, dancing, singing, sporting, and card playing escalated in England, and by the 17th century the Christmas season featured lavish dinners, elaborate masques, and pageants. In 1607, King James I insisted that a play be acted on Christmas night and that the court indulge in games. It was during the Reformation in 16th–17th-century Europe that many Protestants changed the gift bringer to the Christ Child or Christkindl, and the date of giving gifts changed from December 6 to Christmas Eve.
Following the Protestant Reformation, many of the new denominations, including the Anglican Church and Lutheran Church, continued to celebrate Christmas. In 1629, the Anglican poet John Milton penned On the Morning of Christ's Nativity, a poem that has since been read by many during Christmastide. Donald Heinz, a professor at California State University, states that Martin Luther "inaugurated a period in which Germany would produce a unique culture of Christmas, much copied in North America." Among the congregations of the Dutch Reformed Church, Christmas was celebrated as one of the principal evangelical feasts.
However, in 17th century England, some groups such as the Puritans strongly condemned the celebration of Christmas, considering it a Catholic invention and the "trappings of popery" or the "rags of the Beast". In contrast, the established Anglican Church "pressed for a more elaborate observance of feasts, penitential seasons, and saints' days. The calendar reform became a major point of tension between the Anglican party and the Puritan party." The Catholic Church also responded, promoting the festival in a more religiously oriented form. King Charles I of England directed his noblemen and gentry to return to their landed estates in midwinter to keep up their old-style Christmas generosity. Following the Parliamentarian victory over Charles I during the English Civil War, England's Puritan rulers banned Christmas in 1647.
Protests followed as pro-Christmas rioting broke out in several cities and for weeks Canterbury was controlled by the rioters, who decorated doorways with holly and shouted royalist slogans. Football, among the sports the Puritans banned on a Sunday, was also used as a rebellious force: when Puritans outlawed Christmas in England in December 1647 the crowd brought out footballs as a symbol of festive misrule. The book, The Vindication of Christmas (London, 1652), argued against the Puritans, and makes note of Old English Christmas traditions, dinner, roast apples on the fire, card playing, dances with "plow-boys" and "maidservants", old Father Christmas and carol singing. During the ban, semi-clandestine religious services marking Christ's birth continued to be held, and people sang carols in secret.
It was restored as a legal holiday in England with the Restoration of King Charles II in 1660 when Puritan legislation was declared null and void, with Christmas again freely celebrated in England. Many Calvinist clergymen disapproved of Christmas celebration. As such, in Scotland, the Presbyterian Church of Scotland discouraged the observance of Christmas, and though James VI commanded its celebration in 1618, attendance at church was scant. The Parliament of Scotland officially abolished the observance of Christmas in 1640, claiming that the church had been "purged of all superstitious observation of days". Whereas in England, Wales and Ireland Christmas Day is a common law holiday, having been a customary holiday since time immemorial, it was not until 1871 that it was designated a bank holiday in Scotland. Following the Restoration of Charles II, Poor Robin's Almanack contained the lines: "Now thanks to God for Charles return, / Whose absence made old Christmas mourn. / For then we scarcely did it know, / Whether it Christmas were or no." The diary of James Woodforde, from the latter half of the 18th century, details the observance of Christmas and celebrations associated with the season over a number of years.
As in England, Puritans in Colonial America staunchly opposed the observation of Christmas. The Pilgrims of New England pointedly spent their first December 25 in the New World working normally. Puritans such as Cotton Mather condemned Christmas both because scripture did not mention its observance and because Christmas celebrations of the day often involved boisterous behavior. Many non-Puritans in New England deplored the loss of the holidays enjoyed by the laboring classes in England. Christmas observance was outlawed in Boston in 1659. The ban on Christmas observance was revoked in 1681 by English governor Edmund Andros, but it was not until the mid-19th century that celebrating Christmas became fashionable in the Boston region.
At the same time, Christian residents of Virginia and New York observed the holiday freely. Pennsylvania Dutch settlers, predominantly Moravian settlers of Bethlehem, Nazareth, and Lititz in Pennsylvania and the Wachovia settlements in North Carolina, were enthusiastic celebrators of Christmas. The Moravians in Bethlehem had the first Christmas trees in America as well as the first Nativity Scenes. Christmas fell out of favor in the United States after the American Revolution, when it was considered an English custom. George Washington attacked Hessian (German) mercenaries on the day after Christmas during the Battle of Trenton on December 26, 1776, Christmas being much more popular in Germany than in America at this time.
With the atheistic Cult of Reason in power during the era of Revolutionary France, Christian Christmas religious services were banned and the three kings cake was renamed the "equality cake" under anticlerical government policies.
In the early 19th century, Christmas festivities and services became widespread with the rise of the Oxford Movement in the Church of England that emphasized the centrality of Christmas in Christianity and charity to the poor, along with Washington Irving, Charles Dickens, and other authors emphasizing family, children, kind-heartedness, gift-giving, and Santa Claus (for Irving), or Father Christmas (for Dickens).
In the early-19th century, writers imagined Tudor-period Christmas as a time of heartfelt celebration. In 1843, Charles Dickens wrote the novel A Christmas Carol, which helped revive the "spirit" of Christmas and seasonal merriment. Its instant popularity played a major role in portraying Christmas as a holiday emphasizing family, goodwill, and compassion.
Dickens sought to construct Christmas as a family-centered festival of generosity, linking "worship and feasting, within a context of social reconciliation." Superimposing his humanitarian vision of the holiday, in what has been termed "Carol Philosophy", Dickens influenced many aspects of Christmas that are celebrated today in Western culture, such as family gatherings, seasonal food and drink, dancing, games, and a festive generosity of spirit. A prominent phrase from the tale, "Merry Christmas", was popularized following the appearance of the story. This coincided with the appearance of the Oxford Movement and the growth of Anglo-Catholicism, which led a revival in traditional rituals and religious observances.
The term Scrooge became a synonym for miser, with the phrase "Bah! Humbug!" becoming emblematic of a dismissive attitude of the festive spirit. In 1843, the first commercial Christmas card was produced by Sir Henry Cole. The revival of the Christmas Carol began with William Sandys's Christmas Carols Ancient and Modern (1833), with the first appearance in print of "The First Noel", "I Saw Three Ships", "Hark the Herald Angels Sing" and "God Rest Ye Merry, Gentlemen", popularized in Dickens's A Christmas Carol.
In Britain, the Christmas tree was introduced in the early 19th century by the German-born Queen Charlotte. In 1832, the future Queen Victoria wrote about her delight at having a Christmas tree, hung with lights, ornaments, and presents placed round it. After her marriage to her German cousin Prince Albert, by 1841 the custom became more widespread throughout Britain.
An image of the British royal family with their Christmas tree at Windsor Castle created a sensation when it was published in the Illustrated London News in 1848. A modified version of this image was published in Godey's Lady's Book, Philadelphia in 1850. By the 1870s, putting up a Christmas tree had become common in America.
In America, interest in Christmas had been revived in the 1820s by several short stories by Washington Irving which appear in his The Sketch Book of Geoffrey Crayon, Gent. and "Old Christmas". Irving's stories depicted harmonious warm-hearted English Christmas festivities he experienced while staying in Aston Hall, Birmingham, England, that had largely been abandoned, and he used the tract Vindication of Christmas (1652) of Old English Christmas traditions, that he had transcribed into his journal as a format for his stories.
In 1822, Clement Clarke Moore wrote the poem A Visit From St. Nicholas (popularly known by its first line: Twas the Night Before Christmas). The poem helped popularize the tradition of exchanging gifts, and seasonal Christmas shopping began to assume economic importance. This also started the cultural conflict between the holiday's spiritual significance and its associated commercialism that some see as corrupting the holiday. In her 1850 book The First Christmas in New England, Harriet Beecher Stowe includes a character who complains that the true meaning of Christmas was lost in a shopping spree.
While the celebration of Christmas was not yet customary in some regions in the U.S., Henry Wadsworth Longfellow detected "a transition state about Christmas here in New England" in 1856. "The old puritan feeling prevents it from being a cheerful, hearty holiday; though every year makes it more so." In Reading, Pennsylvania, a newspaper remarked in 1861, "Even our presbyterian friends who have hitherto steadfastly ignored Christmas—threw open their church doors and assembled in force to celebrate the anniversary of the Savior's birth."
The First Congregational Church of Rockford, Illinois, "although of genuine Puritan stock", was 'preparing for a grand Christmas jubilee', a news correspondent reported in 1864. By 1860, fourteen states including several from New England had adopted Christmas as a legal holiday. In 1875, Louis Prang introduced the Christmas card to Americans. He has been called the "father of the American Christmas card". On June 28, 1870, Christmas was formally declared a United States federal holiday.
During the First World War and particularly (but not exclusively) in 1914, a series of informal truces took place for Christmas between opposing armies. The truces, which were organised spontaneously by fighting men, ranged from promises not to shoot (shouted at a distance in order to ease the pressure of war for the day) to friendly socializing, gift giving and even sport between enemies. These incidents became a well known and semi-mythologised part of popular memory. They have been described as a symbol of common humanity even in the darkest of situations and used to demonstrate to children the ideals of Christmas.
Up to the 1950s in the UK, many Christmas customs were restricted to the upper and middle classes. Most of the population had not yet adopted many Christmas rituals that later became popular, including Christmas trees. Christmas dinner would normally include beef or goose, not turkey as would later be common. Children would get fruit and sweets in their stocking rather than elaborate gifts. Full celebration of a family Christmas with all the trimmings only became widespread with increased prosperity from the 1950s. National papers were published on Christmas Day until 1912. Post was still delivered on Christmas Day until 1961. League football matches continued in Scotland until the 1970s while in England they ceased at the end of the 1950s.
Under the state atheism of the Soviet Union, after its foundation in 1917, Christmas celebrations—along with other Christian holidays—were prohibited in public. During the 1920s, 1930s, and 1940s, the League of Militant Atheists encouraged school pupils to campaign against Christmas traditions, such as the Christmas tree, as well as other Christian holidays, including Easter; the League established an antireligious holiday to be the 31st of each month as a replacement. At the height of this persecution, in 1929, on Christmas Day, children in Moscow were encouraged to spit on crucifixes as a protest against the holiday. Instead, the importance of the holiday and all its trappings, such as the Christmas tree and gift-giving, was transferred to the New Year. It was not until the dissolution of the Soviet Union in 1991 that the persecution ended and Orthodox Christmas became a state holiday again for the first time in Russia after seven decades.
European History Professor Joseph Perry wrote that likewise, in Nazi Germany, "because Nazi ideologues saw organized religion as an enemy of the totalitarian state, propagandists sought to deemphasize—or eliminate altogether—the Christian aspects of the holiday" and that "Propagandists tirelessly promoted numerous Nazified Christmas songs, which replaced Christian themes with the regime's racial ideologies."
As Christmas celebrations began to spread globally even outside traditional Christian cultures, several Muslim-majority countries began to ban the observance of Christmas, claiming it undermined Islam. In 2023, public Christmas celebrations were cancelled in Bethlehem, the city synonymous with the birth of Jesus. Palestinian leaders of various Christian denominations cited the ongoing Israel–Hamas war in their unanimous decision to cancel celebrations.
Christmas Day is celebrated as a major festival and public holiday in countries around the world, including many whose populations are mostly non-Christian. In some non-Christian areas, periods of former colonial rule introduced the celebration (e.g. Hong Kong); in others, Christian minorities or foreign cultural influences have led populations to observe the holiday. Countries such as Japan, where Christmas is popular despite there being only a small number of Christians, have adopted many of the cultural aspects of Christmas, such as gift-giving, decorations, and Christmas trees. A similar example is in Turkey, being Muslim-majority and with a small number of Christians, where Christmas trees and decorations tend to line public streets during the festival.
Many popular customs associated with Christmas developed independently of the commemoration of Jesus's birth, with some claiming that certain elements are Christianized and have origins in pre-Christian festivals that were celebrated by pagan populations who were later converted to Christianity; other scholars reject these claims and affirm that Christmas customs largely developed in a Christian context. The prevailing atmosphere of Christmas has also continually evolved since the holiday's inception, ranging from a sometimes raucous, drunken, carnival-like state in the Middle Ages, to a tamer family-oriented and children-centered theme introduced in a 19th-century transformation. The celebration of Christmas was banned on more than one occasion within certain groups, such as the Puritans and Jehovah's Witnesses (who do not celebrate birthdays in general), due to concerns that it was too unbiblical.
Prior to and through the early Christian centuries, winter festivals were the most popular of the year in many European pagan cultures. Reasons included the fact that less agricultural work needed to be done during the winter, as well as an expectation of better weather as spring approached. Celtic winter herbs such as mistletoe and ivy, and the custom of kissing under a mistletoe, are common in modern Christmas celebrations in the English-speaking countries.
The pre-Christian Germanic peoples—including the Anglo-Saxons and the Norse—celebrated a winter festival called Yule, held in the late December to early January period, yielding modern English yule, today used as a synonym for Christmas. In Germanic language-speaking areas, numerous elements of modern Christmas folk custom and iconography may have originated from Yule, including the Yule log, Yule boar, and the Yule goat. Often leading a ghostly procession through the sky (the Wild Hunt), the long-bearded god Odin is referred to as "the Yule one" and "Yule father" in Old Norse texts, while other gods are referred to as "Yule beings". On the other hand, as there are no reliable existing references to a Christmas log prior to the 16th century, the burning of the Christmas block may have been an early modern invention by Christians unrelated to the pagan practice.
Among countries with a strong Christian tradition, a variety of Christmas celebrations have developed that incorporate regional and local cultures. For example, in eastern Europe Christmas celebrations incorporated pre-Christian traditions such as the Koleda, which shares parallels with the Christmas carol.
Christmas Day (inclusive of its vigil, Christmas Eve), is a Festival in the Lutheran Churches, a solemnity in the Roman Catholic Church, and a Principal Feast of the Anglican Communion. Other Christian denominations do not rank their feast days but nevertheless place importance on Christmas Eve/Christmas Day, as with other Christian feasts like Easter, Ascension Day, and Pentecost. As such, for Christians, attending a Christmas Eve or Christmas Day church service plays an important part in the recognition of the Christmas season. Christmas, along with Easter, is the period of highest annual church attendance. A 2010 survey by LifeWay Christian Resources found that six in ten Americans attend church services during this time. In the United Kingdom, the Church of England reported an estimated attendance of 2.5 million people at Christmas services in 2015.
Nativity scenes are known from 10th-century Rome. They were popularised by Saint Francis of Assisi from 1223, quickly spreading across Europe. Different types of decorations developed across the Christian world, dependent on local tradition and available resources, and can vary from simple representations of the crib to far more elaborate sets – renowned manger scene traditions include the colourful Kraków szopka in Poland, which imitate Kraków's historical buildings as settings, the elaborate Italian presepi (Neapolitan, Genoese and Bolognese), or the Provençal crèches in southern France, using hand-painted terracotta figurines called santons. In certain parts of the world, notably Sicily, living nativity scenes following the tradition of Saint Francis are a popular alternative to static crèches. The first commercially produced decorations appeared in Germany in the 1860s, inspired by paper chains made by children. In countries where a representation of the Nativity scene is very popular, people are encouraged to compete and create the most original or realistic ones. Within some families, the pieces used to make the representation are considered a valuable family heirloom.
The traditional colors of Christmas decorations are red, green, and gold. Red symbolizes the blood of Jesus, which was shed in his crucifixion; green symbolizes eternal life, and in particular the evergreen tree, which does not lose its leaves in the winter; and gold is the first color associated with Christmas, as one of the three gifts of the Magi, symbolizing royalty.
The Christmas tree was first used by German Lutherans in the 16th century, with records indicating that a Christmas tree was placed in the Cathedral of Strassburg in 1539, under the leadership of the Protestant Reformer, Martin Bucer. In the United States, these "German Lutherans brought the decorated Christmas tree with them; the Moravians put lighted candles on those trees." When decorating the Christmas tree, many individuals place a star at the top of the tree symbolizing the Star of Bethlehem, a fact recorded by The School Journal in 1897. Professor David Albert Jones of Oxford University writes that in the 19th century, it became popular for people to also use an angel to top the Christmas tree in order to symbolize the angels mentioned in the accounts of the Nativity of Jesus. Additionally, in the context of a Christian celebration of Christmas, the Christmas tree, being evergreen in colour, is symbolic of Christ, who offers eternal life; the candles or lights on the tree represent the Light of the World—Jesus—born in Bethlehem. Christian services for family use and public worship have been published for the blessing of a Christmas tree, after it has been erected. The Christmas tree is considered by some as Christianisation of pagan tradition and ritual surrounding the Winter Solstice, which included the use of evergreen boughs, and an adaptation of pagan tree worship; according to eighth-century biographer Æddi Stephanus, Saint Boniface (634–709), who was a missionary in Germany, took an ax to an oak tree dedicated to Thor and pointed out a fir tree, which he stated was a more fitting object of reverence because it pointed to heaven and it had a triangular shape, which he said was symbolic of the Trinity. The English language phrase "Christmas tree" is first recorded in 1835 and represents an importation from the German language.
Since the 16th century, the poinsettia, a native plant from Mexico, has been associated with Christmas carrying the Christian symbolism of the Star of Bethlehem; in that country it is known in Spanish as the Flower of the Holy Night. Other popular holiday plants include holly, mistletoe, red amaryllis, and Christmas cactus.
Other traditional decorations include bells, candles, candy canes, stockings, wreaths, and angels. Both the displaying of wreaths and candles in each window are a more traditional Christmas display. The concentric assortment of leaves, usually from an evergreen, make up Christmas wreaths and are designed to prepare Christians for the Advent season. Candles in each window are meant to demonstrate the fact that Christians believe that Jesus Christ is the ultimate light of the world.
Christmas lights and banners may be hung along streets, music played from speakers, and Christmas trees placed in prominent places. It is common in many parts of the world for town squares and consumer shopping areas to sponsor and display decorations. Rolls of brightly colored paper with secular or religious Christmas motifs are manufactured for the purpose of wrapping gifts. In some countries, Christmas decorations are traditionally taken down on Twelfth Night.
For the Christian celebration of Christmas, the viewing of the Nativity play is one of the oldest Christmastime traditions, with the first reenactment of the Nativity of Jesus taking place in 1223 AD. In that year, Francis of Assisi assembled a Nativity scene outside of his church in Italy and children sung Christmas carols celebrating the birth of Jesus. Each year, this grew larger and people travelled from afar to see Francis's depiction of the Nativity of Jesus that came to feature drama and music. Nativity plays eventually spread throughout all of Europe, where they remain popular. Christmas Eve and Christmas Day church services often came to feature Nativity plays, as did schools and theatres. In France, Germany, Mexico and Spain, Nativity plays are often reenacted outdoors in the streets.
The earliest extant specifically Christmas hymns appear in fourth-century Rome. Latin hymns such as "Veni redemptor gentium", written by Ambrose, Archbishop of Milan, were austere statements of the theological doctrine of the Incarnation in opposition to Arianism. "Corde natus ex Parentis" ("Of the Father's love begotten") by the Spanish poet Prudentius (died 413) is still sung in some churches today. In the 9th and 10th centuries, the Christmas "Sequence" or "Prose" was introduced in North European monasteries, developing under Bernard of Clairvaux into a sequence of rhymed stanzas. In the 12th century the Parisian monk Adam of St. Victor began to derive music from popular songs, introducing something closer to the traditional Christmas carol. Christmas carols in English appear in a 1426 work of John Awdlay who lists twenty five "caroles of Cristemas", probably sung by groups of 'wassailers', who went from house to house.
The songs now known specifically as carols were originally communal folk songs sung during celebrations such as "harvest tide" as well as Christmas. It was only later that carols began to be sung in church. Traditionally, carols have often been based on medieval chord patterns, and it is this that gives them their uniquely characteristic musical sound. Some carols like "Personent hodie", "Good King Wenceslas", and "In dulci jubilo" can be traced directly back to the Middle Ages. They are among the oldest musical compositions still regularly sung. "Adeste Fideles" (O Come all ye faithful) appeared in its current form in the mid-18th century.
The singing of carols increased in popularity after the Protestant Reformation in the Lutheran areas of Europe, as the Reformer Martin Luther wrote carols and encouraged their use in worship, in addition to spearheading the practice of caroling outside the Mass. The 18th-century English reformer Charles Wesley, a founder of Methodism, understood the importance of music to Christian worship. In addition to setting many psalms to melodies, he wrote texts for at least three Christmas carols. The best known was originally entitled "Hark! How All the Welkin Rings", later renamed "Hark! The Herald Angels Sing".
Christmas seasonal songs of a nonreligious nature emerged in the late 18th century. The Welsh melody for "Deck the Halls" dates from 1794, with the lyrics added by Scottish musician Thomas Oliphant in 1862, and the American "Jingle Bells" was copyrighted in 1857. Other popular carols include "The First Noel", "God Rest You Merry, Gentlemen", "The Holly and the Ivy", "I Saw Three Ships", "In the Bleak Midwinter", "Joy to the World", "Once in Royal David's City" and "While Shepherds Watched Their Flocks". In the 19th and 20th centuries, African American spirituals and songs about Christmas, based in their tradition of spirituals, became more widely known. An increasing number of seasonal holiday songs were commercially produced in the 20th century, including jazz and blues variations. In addition, there was a revival of interest in early music, from groups singing folk music, such as The Revels, to performers of early medieval and classical music.
One of the most ubiquitous festive songs is "We Wish You a Merry Christmas", which originates from the West Country of England in the 1930s. Radio has covered Christmas music from variety shows from the 1940s and 1950s, as well as modern-day stations that exclusively play Christmas music from late November through December 25. Hollywood movies have featured new Christmas music, such as "White Christmas" in Holiday Inn and Rudolph the Red-Nosed Reindeer. Traditional carols have also been included in Hollywood films, such as "Hark! The Herald Angels Sing" in It's a Wonderful Life (1946), and "Silent Night" in A Christmas Story.
A special Christmas family meal is traditionally an important part of the holiday's celebration, and the food that is served varies greatly from country to country. Some regions have special meals for Christmas Eve, such as Sicily, where 12 kinds of fish are served. In the United Kingdom and countries influenced by its traditions, a standard Christmas meal includes turkey, goose or other large bird, gravy, potatoes, vegetables, sometimes bread and cider. Special desserts are also prepared, such as Christmas pudding, mince pies, Christmas cake, Panettone and Yule log cake. A traditional Christmas meal in Central Europe features fried carp or other fish.
Christmas cards are illustrated messages of greeting exchanged between friends and family members during the weeks preceding Christmas Day. The traditional greeting reads "wishing you a Merry Christmas and a Happy New Year", much like that of the first commercial Christmas card, produced by Sir Henry Cole in London in 1843. The custom of sending them has become popular among a wide cross-section of people with the emergence of the modern trend towards exchanging E-cards.
Christmas cards are purchased in considerable quantities and feature artwork, commercially designed and relevant to the season. The content of the design might relate directly to the Christmas narrative, with depictions of the Nativity of Jesus, or Christian symbols such as the Star of Bethlehem, or a white dove, which can represent both the Holy Spirit and Peace on Earth. Other Christmas cards are more secular and can depict Christmas traditions, mythical figures such as Santa Claus, objects directly associated with Christmas such as candles, holly, and baubles, or a variety of images associated with the season, such as Christmastide activities, snow scenes, and the wildlife of the northern winter.
Some prefer cards with a poem, prayer, or Biblical verse; while others distance themselves from religion with an all-inclusive "Season's greetings".
A number of nations have issued commemorative stamps at Christmastide. Postal customers will often use these stamps to mail Christmas cards, and they are popular with philatelists. These stamps are regular postage stamps, unlike Christmas seals, and are valid for postage year-round. They usually go on sale sometime between early October and early December and are printed in considerable quantities.
The exchanging of gifts is one of the core aspects of the modern Christmas celebration, making it the most profitable time of year for retailers and businesses throughout the world. On Christmas, people exchange gifts based on the Christian tradition associated with Saint Nicholas, and the gifts of gold, frankincense, and myrrh which were given to the baby Jesus by the Magi. The practice of gift giving in the Roman celebration of Saturnalia may have influenced Christian customs, but on the other hand the Christian "core dogma of the Incarnation, however, solidly established the giving and receiving of gifts as the structural principle of that recurrent yet unique event", because it was the Biblical Magi, "together with all their fellow men, who received the gift of God through man's renewed participation in the divine life." However, Thomas J. Talley holds that the Roman Emperor Aurelian placed the alternate festival on December 25 in order to compete with the growing rate of the Christian Church, which had already been celebrating Christmas on that date first.
A number of figures are associated with Christmas and the seasonal giving of gifts. Among these are Father Christmas, also known as Santa Claus (derived from the Dutch for Saint Nicholas), Père Noël, and the Weihnachtsmann; Saint Nicholas or Sinterklaas; the Christkind; Kris Kringle; Joulupukki; tomte/nisse; Babbo Natale; Saint Basil; and Ded Moroz. The Scandinavian tomte (also called nisse) is sometimes depicted as a gnome instead of Santa Claus.
The best known of these figures today is red-dressed Santa Claus, of diverse origins. The name 'Santa Claus' can be traced back to the Dutch Sinterklaas ('Saint Nicholas'). Nicholas was a 4th-century Greek bishop of Myra, a city in the Roman province of Lycia, whose ruins are 3 kilometres (1.9 mi) from modern Demre in southwest Turkey. Among other saintly attributes, he was noted for the care of children, generosity, and the giving of gifts. His feast day, December 6, came to be celebrated in many countries with the giving of gifts.
Saint Nicholas traditionally appeared in bishop's attire, accompanied by helpers, inquiring about the behaviour of children during the past year before deciding whether they deserved a gift or not. By the 13th century, Saint Nicholas was well known in the Netherlands, and the practice of gift-giving in his name spread to other parts of central and southern Europe. At the Reformation in 16th- and 17th-century Europe, many Protestants changed the gift bringer to the Christ Child or Christkindl, corrupted in English to 'Kris Kringle', and the date of giving gifts changed from December 6 to Christmas Eve.
The modern popular image of Santa Claus, however, was created in the United States, and in particular in New York. The transformation was accomplished with the aid of notable contributors including Washington Irving and the German-American cartoonist Thomas Nast (1840–1902). Following the American Revolutionary War, some of the inhabitants of New York City sought out symbols of the city's non-English past. New York had originally been established as the Dutch colonial town of New Amsterdam and the Dutch Sinterklaas tradition was reinvented as Saint Nicholas.
Current tradition in several Latin American countries (such as Venezuela and Colombia) holds that while Santa makes the toys, he then gives them to the Baby Jesus, who is the one who actually delivers them to the children's homes, a reconciliation between traditional religious beliefs and the iconography of Santa Claus imported from the United States.
In Italy's South Tyrol, Austria, the Czech Republic, Southern Germany, Hungary, Liechtenstein, Slovakia, and Switzerland, the Christkind (Ježíšek in Czech, Jézuska in Hungarian and Ježiško in Slovak) brings the presents. Greek children get their presents from Saint Basil on New Year's Eve, the eve of that saint's liturgical feast. The German St. Nikolaus is not identical with the Weihnachtsmann (who is the German version of Santa Claus / Father Christmas). St. Nikolaus wears a bishop's dress and still brings small gifts (usually candies, nuts, and fruits) on December 6 and is accompanied by Knecht Ruprecht. Although many parents around the world routinely teach their children about Santa Claus and other gift bringers, some have come to reject this practice, considering it deceptive.
Multiple gift-giver figures exist in Poland, varying between regions and individual families. St Nicholas (Święty Mikołaj) dominates Central and North-East areas, the Starman (Gwiazdor) is most common in Greater Poland, Baby Jesus (Dzieciątko) is unique to Upper Silesia, with the Little Star (Gwiazdka) and the Little Angel (Aniołek) being common in the South and the South-East. Grandfather Frost (Dziadek Mróz) is less commonly accepted in some areas of Eastern Poland. It is worth noting that across all of Poland, St Nicholas is the gift giver on Saint Nicholas Day on December 6.
Christmas during the Middle Ages was a public festival with annual indulgences included the sporting. When Puritans outlawed Christmas in England in December 1647 the crowd brought out footballs as a symbol of festive misrule. The Orkney Christmas Day Ba' tradition continues. In the former top tier of English football, home and away Christmas Day and Boxing Day double headers were often played guaranteeing football clubs large crowds by allowing many working people their only chance to watch a game. Champions Preston North End faced Aston Villa on Christmas Day 1889 and the last 25 December fixture was in 1965 in England, Blackpool beating Blackburn Rovers 4–2. One of the most memorable images of the Christmas truce during World War I was the games of football played between the opposing sides on Christmas Day 1914.
More recently, in the United States, both NFL and NBA have held fixtures on Christmas Day.
There are two main theories behind December 25 becoming the traditional date for Christmas, although Theology professor Susan Roll says that "No liturgical historian [...] goes so far as to deny that it has any sort of relation with the sun, the winter solstice and the popularity of solar worship in the later Roman Empire". December 25 was the date of the winter solstice in the Roman calendar. Some early Christian writers noted the solar symbolism in placing Jesus's birthday at the winter solstice and John's birthday at the summer solstice.
The 'history of religions' theory suggests the Church chose December 25 as Christ's birthday (dies Natalis Christi) to appropriate the Roman winter solstice festival dies Natalis Solis Invicti (birthday of Sol Invictus, the 'Invincible Sun'), held on this date since 274 AD. The early Church linked Jesus Christ to the Sun and referred to him as the 'Sun of Righteousness' (Sol Justitiae) prophesied by Malachi. Gary Forsythe, Professor of Ancient History, says that the Natalis Solis Invicti followed "the seven-day period of the Saturnalia (December 17–23), Rome's most joyous holiday season since Republican times, characterized by parties, banquets, and exchanges of gifts".
Another theory, the 'computation hypothesis' or 'calculation theory', notes that December 25 is nine months after March 25, a date chosen as Jesus's conception (the Annunciation) and the date of the spring equinox on the Roman calendar.
Some jurisdictions of the Eastern Orthodox Church, including those of Russia, Georgia, Macedonia, Montenegro, Serbia, and Jerusalem, mark feasts using the older Julian calendar. As of 2023, there is a difference of 13 days between the Julian calendar and the modern Gregorian calendar, which is used internationally for most secular purposes. As a result, December 25 on the Julian calendar currently corresponds to January 7 on the calendar used by most governments and people in everyday life. Therefore, the aforementioned Orthodox Christians mark December 25 (and thus Christmas) on the day that is internationally considered to be January 7.
However, following the Council of Constantinople in 1923, other Orthodox Christians, such as those belonging to the jurisdictions of Constantinople, Bulgaria, Greece, Romania, Antioch, Alexandria, Albania, Cyprus, Finland, and the Orthodox Church in America, among others, began using the Revised Julian calendar, which at present corresponds exactly to the Gregorian calendar. Therefore, these Orthodox Christians mark December 25 (and thus Christmas) on the same day that is internationally considered to be December 25.
A further complication is added by the fact that the Armenian Apostolic Church continues the original ancient Eastern Christian practice of celebrating the birth of Christ not as a separate holiday, but on the same day as the celebration of his baptism (Theophany), which is on January 6. This is a public holiday in Armenia, and it is held on the same day that is internationally considered to be January 6, because since 1923 the Armenian Church in Armenia has used the Gregorian calendar.
However, there is also a small Armenian Patriarchate of Jerusalem, which maintains the traditional Armenian custom of celebrating the birth of Christ on the same day as Theophany (January 6), but uses the Julian calendar for the determination of that date. As a result, this church celebrates "Christmas" (more properly called Theophany) on the day that is considered January 19 on the Gregorian calendar in use by the majority of the world.
Following the 2022 invasion of its territory by Russia, Ukraine officially moved its Christmas date from January 7 to December 25, to distance itself from the Russian Orthodox Church that had supported Russia's invasion. This followed the Orthodox Church of Ukraine formally adopting the Revised Julian calendar for fixed feasts and solemnities.
There are four different dates used by different Christian groups to mark the birth of Christ, given in the table below.
Christmas is typically a peak selling season for retailers in many nations around the world. Sales increase dramatically as people purchase gifts, decorations, and supplies to celebrate. In the United States, the "Christmas shopping season" starts as early as October. In Canada, merchants begin advertising campaigns just before Halloween (October 31), and step up their marketing following Remembrance Day on November 11. In the UK and Ireland, the Christmas shopping season starts from mid-November, around the time when high street Christmas lights are turned on. In the United States, it has been calculated that a quarter of all personal spending takes place during the Christmas/holiday shopping season. Figures from the U.S. Census Bureau reveal that expenditure in department stores nationwide rose from $20.8 billion in November 2004 to $31.9 billion in December 2004, an increase of 54 percent. In other sectors, the pre-Christmas increase in spending was even greater, there being a November–December buying surge of 100 percent in bookstores and 170 percent in jewelry stores. In the same year employment in American retail stores rose from 1.6 million to 1.8 million in the two months leading up to Christmas. Industries completely dependent on Christmas include Christmas cards, of which 1.9 billion are sent in the United States each year, and live Christmas trees, of which 20.8 million were cut in the U.S. in 2002. For 2019, the average US adult was projected to spend $920 on gifts alone. In the UK in 2010, up to £8 billion was expected to be spent online at Christmas, approximately a quarter of total retail festive sales.
In most Western nations, Christmas Day is the least active day of the year for business and commerce; almost all retail, commercial and institutional businesses are closed, and almost all industries cease activity (more than any other day of the year), whether laws require such or not. In England and Wales, the Christmas Day (Trading) Act 2004 prevents all large shops from trading on Christmas Day. Similar legislation was approved in Scotland in 2007. Film studios release many high-budget movies during the holiday season, including Christmas films, fantasy movies or high-tone dramas with high production values to hopes of maximizing the chance of nominations for the Academy Awards.
One economist's analysis calculates that, despite increased overall spending, Christmas is a deadweight loss under orthodox microeconomic theory, because of the effect of gift-giving. This loss is calculated as the difference between what the gift giver spent on the item and what the gift receiver would have paid for the item. It is estimated that in 2001, Christmas resulted in a $4 billion deadweight loss in the U.S. alone. Because of complicating factors, this analysis is sometimes used to discuss possible flaws in current microeconomic theory. Other deadweight losses include the effects of Christmas on the environment and the fact that material gifts are often perceived as white elephants, imposing cost for upkeep and storage and contributing to clutter.
Christmas has at times been the subject of controversy and attacks from various sources, both Christian and non-Christian. Historically, it was prohibited by Puritans during their ascendency in the Commonwealth of England (1647–1660), and in Colonial New England where the Puritans outlawed the celebration of Christmas in 1659 on the grounds that Christmas was not mentioned in Scripture and therefore violated the Reformed regulative principle of worship. The Parliament of Scotland, which was dominated by Presbyterians, passed a series of acts outlawing the observance of Christmas between 1637 and 1690; Christmas Day did not become a public holiday in Scotland until 1871. Today, some conservative Reformed denominations such as the Free Presbyterian Church of Scotland and the Reformed Presbyterian Church of North America likewise reject the celebration of Christmas based on the regulative principle and what they see as its non-Scriptural origin. Christmas celebrations have also been prohibited by atheist states such as the Soviet Union and more recently majority Muslim states such as Somalia, Tajikistan and Brunei.
Some Christians and organizations such as Pat Robertson's American Center for Law and Justice cite alleged attacks on Christmas (dubbing them a "war on Christmas"). Such groups claim that any specific mention of the term "Christmas" or its religious aspects is being increasingly censored, avoided, or discouraged by a number of advertisers, retailers, government (prominently schools), and other public and private organizations. One controversy is the occurrence of Christmas trees being renamed Holiday trees. In the U.S. there has been a tendency to replace the greeting Merry Christmas with Happy Holidays, which is considered inclusive at the time of the Jewish celebration of Hanukkah. In the U.S. and Canada, where the use of the term "Holidays" is most prevalent, opponents have denounced its usage and avoidance of using the term "Christmas" as being politically correct. In 1984, the U.S. Supreme Court ruled in Lynch v. Donnelly that a Christmas display (which included a Nativity scene) owned and displayed by the city of Pawtucket, Rhode Island, did not violate the First Amendment. American Muslim scholar Abdul Malik Mujahid has said that Muslims must treat Christmas with respect, even if they disagree with it.
The government of the People's Republic of China officially espouses state atheism, and has conducted antireligious campaigns to this end. In December 2018, officials raided Christian churches prior to Christmastide and coerced them to close; Christmas trees and Santa Clauses were also forcibly removed. | [
{
"paragraph_id": 0,
"text": "Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25 as a religious and cultural celebration among billions of people around the world. A feast central to the liturgical year in Christianity, it follows the season of Advent (which begins four Sundays before) or the Nativity Fast, and initiates the season of Christmastide, which historically in the West lasts twelve days and culminates on Twelfth Night. Christmas Day is a public holiday in many countries, is celebrated religiously by a majority of Christians, as well as culturally by many non-Christians, and forms an integral part of the holiday season surrounding it.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The traditional Christmas narrative recounted in the New Testament, known as the Nativity of Jesus, says that Jesus was born in Bethlehem, in accordance with messianic prophecies. When Joseph and Mary arrived in the city, the inn had no room, and so they were offered a stable where the Christ Child was soon born, with angels proclaiming this news to shepherds, who then spread the word.",
"title": ""
},
{
"paragraph_id": 2,
"text": "There are different hypotheses regarding the date of Jesus's birth, and in the early fourth century, the church fixed the date as December 25. This corresponds to the traditional date of the winter solstice on the Roman calendar. It is exactly nine months after Annunciation on March 25, also the date of the spring equinox. Most Christians celebrate on December 25 in the Gregorian calendar, which has been adopted almost universally in the civil calendars used in countries throughout the world. However, part of the Eastern Christian Churches celebrate Christmas on December 25 of the older Julian calendar, which currently corresponds to January 7 in the Gregorian calendar. For Christians, believing that God came into the world in the form of man to atone for the sins of humanity rather than knowing Jesus's exact birth date is considered to be the primary purpose of celebrating Christmas.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The customs associated with Christmas in various countries have a mix of pre-Christian, Christian, and secular themes and origins. Popular holiday traditions include gift giving; completing an Advent calendar or Advent wreath; Christmas music and caroling; watching Christmas movies; viewing a Nativity play; an exchange of Christmas cards; attending church services; a special meal; and displaying various Christmas decorations, including Christmas trees, Christmas lights, nativity scenes, garlands, wreaths, mistletoe, and holly. Additionally, several related and often interchangeable figures, known as Santa Claus, Father Christmas, Saint Nicholas, and Christkind, are associated with bringing gifts to children during the Christmas season and have their own body of traditions and lore. Because gift-giving and many other aspects of the Christmas festival involve heightened economic activity, the holiday has become a significant event and a key sales period for retailers and businesses. Over the past few centuries, Christmas has had a steadily growing economic effect in many regions of the world.",
"title": ""
},
{
"paragraph_id": 4,
"text": "The English word Christmas is a shortened form of 'Christ's Mass'. The word is recorded as Crīstesmæsse in 1038 and Cristes-messe in 1131. Crīst (genitive Crīstes) is from the Greek Χριστός (Khrīstos, 'Christ'), a translation of the Hebrew מָשִׁיחַ (Māšîaḥ, 'Messiah'), meaning 'anointed'; and mæsse is from the Latin missa, the celebration of the Eucharist.",
"title": "Etymology"
},
{
"paragraph_id": 5,
"text": "The form Christenmas was also used during some periods, but is now considered archaic and dialectal. The term derives from Middle English Cristenmasse, meaning 'Christian mass'. Xmas is an abbreviation of Christmas found particularly in print, based on the initial letter chi (Χ) in the Greek Χριστός, although some style guides discourage its use. This abbreviation has precedent in Middle English Χρ̄es masse (where Χρ̄ is another abbreviation of the Greek word).",
"title": "Etymology"
},
{
"paragraph_id": 6,
"text": "The holiday has had various other English names throughout its history. The Anglo-Saxons referred to the feast as \"midwinter\", or, more rarely, as Nātiuiteð (from the Latin nātīvitās below). Nativity, meaning 'birth', is from the Latin nātīvitās. In Old English, Gēola ('Yule') referred to the period corresponding to December and January, which was eventually equated with Christian Christmas. 'Noel' (also 'Nowel' or 'Nowell', as in \"The First Nowell\") entered English in the late 14th century and is from the Old French noël or naël, itself ultimately from the Latin nātālis (diēs) meaning 'birth (day)'.",
"title": "Etymology"
},
{
"paragraph_id": 7,
"text": "Koleda is the traditional Slavic name for Christmas and the period from Christmas to Epiphany or, more generally, to Slavic Christmas-related rituals, some dating to pre-Christian times.",
"title": "Etymology"
},
{
"paragraph_id": 8,
"text": "The gospels of Luke and Matthew describe Jesus as being born in Bethlehem to the Virgin Mary. In the Gospel of Luke, Joseph and Mary travel from Nazareth to Bethlehem in order to be counted for a census, and Jesus is born there and placed in a manger. Angels proclaim him a savior for all people, and three shepherds come to adore him. In the Gospel of Matthew, by contrast, three magi follow a star to Bethlehem to bring gifts to Jesus, born the king of the Jews. King Herod orders the massacre of all the boys less than two years old in Bethlehem, but the family flees to Egypt and later returns to Nazareth.",
"title": "Nativity"
},
{
"paragraph_id": 9,
"text": "In the 2nd century, the \"earliest church records\" indicate that \"Christians were remembering and celebrating the birth of the Lord\", an \"observance [that] sprang up organically from the authentic devotion of ordinary believers\"; although \"they did not agree upon a set date\". The earliest evidence of Christ's birth being marked on December 25 is a sentence in the Chronograph of 354. Liturgical historians generally agree that this part of the text was written in Rome in AD 336. Though Christmas did not appear on the lists of festivals given by the early Christian writers Irenaeus and Tertullian, the early Church Fathers John Chrysostom, Augustine of Hippo, and Jerome attested to December 25 as the date of Christmas toward the end of the fourth century. December 25 was the traditional date of the winter solstice in the Roman Empire, where most Christians lived, and the Roman festival Dies Natalis Solis Invicti (birthday of Sol Invictus, the 'Invincible Sun') had been held on this date since 274 AD.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "In the East, the birth of Jesus was celebrated in connection with the Epiphany on January 6. This holiday was not primarily about Christ's birth, but rather his baptism. Christmas was promoted in the East as part of the revival of Orthodox Christianity that followed the death of the pro-Arian Emperor Valens at the Battle of Adrianople in 378. The feast was introduced in Constantinople in 379, in Antioch by John Chrysostom towards the end of the fourth century, probably in 388, and in Alexandria in the following century. The Georgian Iadgari demonstrates that Christmas was celebrated in Jerusalem by the sixth century.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "In the Early Middle Ages, Christmas Day was overshadowed by Epiphany, which in western Christianity focused on the visit of the magi. However, the medieval calendar was dominated by Christmas-related holidays. The forty days before Christmas became the \"forty days of St. Martin\" (which began on November 11, the feast of St. Martin of Tours), now known as Advent. In Italy, former Saturnalian traditions were attached to Advent. Around the 12th century, these traditions transferred again to the Twelve Days of Christmas (December 25–January 5); a time that appears in the liturgical calendars as Christmastide or Twelve Holy Days.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "In 567, the Council of Tours put in place the season of Christmastide, proclaiming \"the twelve days from Christmas to Epiphany as a sacred and festive season, and established the duty of Advent fasting in preparation for the feast.\" This was done in order to solve the \"administrative problem for the Roman Empire as it tried to coordinate the solar Julian calendar with the lunar calendars of its provinces in the east.\"",
"title": "History"
},
{
"paragraph_id": 13,
"text": "The prominence of Christmas Day increased gradually after Charlemagne was crowned Emperor on Christmas Day in 800. King Edmund the Martyr was anointed on Christmas in 855 and King William I of England was crowned on Christmas Day 1066.",
"title": "History"
},
{
"paragraph_id": 14,
"text": "By the High Middle Ages, the holiday had become so prominent that chroniclers routinely noted where various magnates celebrated Christmas. King Richard II of England hosted a Christmas feast in 1377 at which 28 oxen and 300 sheep were eaten. The Yule boar was a common feature of medieval Christmas feasts. Caroling also became popular, and was originally performed by a group of dancers who sang. The group was composed of a lead singer and a ring of dancers that provided the chorus. Various writers of the time condemned caroling as lewd, indicating that the unruly traditions of Saturnalia and Yule may have continued in this form. \"Misrule\"—drunkenness, promiscuity, gambling—was also an important aspect of the festival. In England, gifts were exchanged on New Year's Day, and there was special Christmas ale.",
"title": "History"
},
{
"paragraph_id": 15,
"text": "Christmas during the Middle Ages was a public festival that incorporated ivy, holly, and other evergreens. Christmas gift-giving during the Middle Ages was usually between people with legal relationships, such as tenant and landlord. The annual indulgence in eating, dancing, singing, sporting, and card playing escalated in England, and by the 17th century the Christmas season featured lavish dinners, elaborate masques, and pageants. In 1607, King James I insisted that a play be acted on Christmas night and that the court indulge in games. It was during the Reformation in 16th–17th-century Europe that many Protestants changed the gift bringer to the Christ Child or Christkindl, and the date of giving gifts changed from December 6 to Christmas Eve.",
"title": "History"
},
{
"paragraph_id": 16,
"text": "Following the Protestant Reformation, many of the new denominations, including the Anglican Church and Lutheran Church, continued to celebrate Christmas. In 1629, the Anglican poet John Milton penned On the Morning of Christ's Nativity, a poem that has since been read by many during Christmastide. Donald Heinz, a professor at California State University, states that Martin Luther \"inaugurated a period in which Germany would produce a unique culture of Christmas, much copied in North America.\" Among the congregations of the Dutch Reformed Church, Christmas was celebrated as one of the principal evangelical feasts.",
"title": "History"
},
{
"paragraph_id": 17,
"text": "However, in 17th century England, some groups such as the Puritans strongly condemned the celebration of Christmas, considering it a Catholic invention and the \"trappings of popery\" or the \"rags of the Beast\". In contrast, the established Anglican Church \"pressed for a more elaborate observance of feasts, penitential seasons, and saints' days. The calendar reform became a major point of tension between the Anglican party and the Puritan party.\" The Catholic Church also responded, promoting the festival in a more religiously oriented form. King Charles I of England directed his noblemen and gentry to return to their landed estates in midwinter to keep up their old-style Christmas generosity. Following the Parliamentarian victory over Charles I during the English Civil War, England's Puritan rulers banned Christmas in 1647.",
"title": "History"
},
{
"paragraph_id": 18,
"text": "Protests followed as pro-Christmas rioting broke out in several cities and for weeks Canterbury was controlled by the rioters, who decorated doorways with holly and shouted royalist slogans. Football, among the sports the Puritans banned on a Sunday, was also used as a rebellious force: when Puritans outlawed Christmas in England in December 1647 the crowd brought out footballs as a symbol of festive misrule. The book, The Vindication of Christmas (London, 1652), argued against the Puritans, and makes note of Old English Christmas traditions, dinner, roast apples on the fire, card playing, dances with \"plow-boys\" and \"maidservants\", old Father Christmas and carol singing. During the ban, semi-clandestine religious services marking Christ's birth continued to be held, and people sang carols in secret.",
"title": "History"
},
{
"paragraph_id": 19,
"text": "It was restored as a legal holiday in England with the Restoration of King Charles II in 1660 when Puritan legislation was declared null and void, with Christmas again freely celebrated in England. Many Calvinist clergymen disapproved of Christmas celebration. As such, in Scotland, the Presbyterian Church of Scotland discouraged the observance of Christmas, and though James VI commanded its celebration in 1618, attendance at church was scant. The Parliament of Scotland officially abolished the observance of Christmas in 1640, claiming that the church had been \"purged of all superstitious observation of days\". Whereas in England, Wales and Ireland Christmas Day is a common law holiday, having been a customary holiday since time immemorial, it was not until 1871 that it was designated a bank holiday in Scotland. Following the Restoration of Charles II, Poor Robin's Almanack contained the lines: \"Now thanks to God for Charles return, / Whose absence made old Christmas mourn. / For then we scarcely did it know, / Whether it Christmas were or no.\" The diary of James Woodforde, from the latter half of the 18th century, details the observance of Christmas and celebrations associated with the season over a number of years.",
"title": "History"
},
{
"paragraph_id": 20,
"text": "As in England, Puritans in Colonial America staunchly opposed the observation of Christmas. The Pilgrims of New England pointedly spent their first December 25 in the New World working normally. Puritans such as Cotton Mather condemned Christmas both because scripture did not mention its observance and because Christmas celebrations of the day often involved boisterous behavior. Many non-Puritans in New England deplored the loss of the holidays enjoyed by the laboring classes in England. Christmas observance was outlawed in Boston in 1659. The ban on Christmas observance was revoked in 1681 by English governor Edmund Andros, but it was not until the mid-19th century that celebrating Christmas became fashionable in the Boston region.",
"title": "History"
},
{
"paragraph_id": 21,
"text": "At the same time, Christian residents of Virginia and New York observed the holiday freely. Pennsylvania Dutch settlers, predominantly Moravian settlers of Bethlehem, Nazareth, and Lititz in Pennsylvania and the Wachovia settlements in North Carolina, were enthusiastic celebrators of Christmas. The Moravians in Bethlehem had the first Christmas trees in America as well as the first Nativity Scenes. Christmas fell out of favor in the United States after the American Revolution, when it was considered an English custom. George Washington attacked Hessian (German) mercenaries on the day after Christmas during the Battle of Trenton on December 26, 1776, Christmas being much more popular in Germany than in America at this time.",
"title": "History"
},
{
"paragraph_id": 22,
"text": "With the atheistic Cult of Reason in power during the era of Revolutionary France, Christian Christmas religious services were banned and the three kings cake was renamed the \"equality cake\" under anticlerical government policies.",
"title": "History"
},
{
"paragraph_id": 23,
"text": "In the early 19th century, Christmas festivities and services became widespread with the rise of the Oxford Movement in the Church of England that emphasized the centrality of Christmas in Christianity and charity to the poor, along with Washington Irving, Charles Dickens, and other authors emphasizing family, children, kind-heartedness, gift-giving, and Santa Claus (for Irving), or Father Christmas (for Dickens).",
"title": "History"
},
{
"paragraph_id": 24,
"text": "In the early-19th century, writers imagined Tudor-period Christmas as a time of heartfelt celebration. In 1843, Charles Dickens wrote the novel A Christmas Carol, which helped revive the \"spirit\" of Christmas and seasonal merriment. Its instant popularity played a major role in portraying Christmas as a holiday emphasizing family, goodwill, and compassion.",
"title": "History"
},
{
"paragraph_id": 25,
"text": "Dickens sought to construct Christmas as a family-centered festival of generosity, linking \"worship and feasting, within a context of social reconciliation.\" Superimposing his humanitarian vision of the holiday, in what has been termed \"Carol Philosophy\", Dickens influenced many aspects of Christmas that are celebrated today in Western culture, such as family gatherings, seasonal food and drink, dancing, games, and a festive generosity of spirit. A prominent phrase from the tale, \"Merry Christmas\", was popularized following the appearance of the story. This coincided with the appearance of the Oxford Movement and the growth of Anglo-Catholicism, which led a revival in traditional rituals and religious observances.",
"title": "History"
},
{
"paragraph_id": 26,
"text": "The term Scrooge became a synonym for miser, with the phrase \"Bah! Humbug!\" becoming emblematic of a dismissive attitude of the festive spirit. In 1843, the first commercial Christmas card was produced by Sir Henry Cole. The revival of the Christmas Carol began with William Sandys's Christmas Carols Ancient and Modern (1833), with the first appearance in print of \"The First Noel\", \"I Saw Three Ships\", \"Hark the Herald Angels Sing\" and \"God Rest Ye Merry, Gentlemen\", popularized in Dickens's A Christmas Carol.",
"title": "History"
},
{
"paragraph_id": 27,
"text": "In Britain, the Christmas tree was introduced in the early 19th century by the German-born Queen Charlotte. In 1832, the future Queen Victoria wrote about her delight at having a Christmas tree, hung with lights, ornaments, and presents placed round it. After her marriage to her German cousin Prince Albert, by 1841 the custom became more widespread throughout Britain.",
"title": "History"
},
{
"paragraph_id": 28,
"text": "An image of the British royal family with their Christmas tree at Windsor Castle created a sensation when it was published in the Illustrated London News in 1848. A modified version of this image was published in Godey's Lady's Book, Philadelphia in 1850. By the 1870s, putting up a Christmas tree had become common in America.",
"title": "History"
},
{
"paragraph_id": 29,
"text": "In America, interest in Christmas had been revived in the 1820s by several short stories by Washington Irving which appear in his The Sketch Book of Geoffrey Crayon, Gent. and \"Old Christmas\". Irving's stories depicted harmonious warm-hearted English Christmas festivities he experienced while staying in Aston Hall, Birmingham, England, that had largely been abandoned, and he used the tract Vindication of Christmas (1652) of Old English Christmas traditions, that he had transcribed into his journal as a format for his stories.",
"title": "History"
},
{
"paragraph_id": 30,
"text": "In 1822, Clement Clarke Moore wrote the poem A Visit From St. Nicholas (popularly known by its first line: Twas the Night Before Christmas). The poem helped popularize the tradition of exchanging gifts, and seasonal Christmas shopping began to assume economic importance. This also started the cultural conflict between the holiday's spiritual significance and its associated commercialism that some see as corrupting the holiday. In her 1850 book The First Christmas in New England, Harriet Beecher Stowe includes a character who complains that the true meaning of Christmas was lost in a shopping spree.",
"title": "History"
},
{
"paragraph_id": 31,
"text": "While the celebration of Christmas was not yet customary in some regions in the U.S., Henry Wadsworth Longfellow detected \"a transition state about Christmas here in New England\" in 1856. \"The old puritan feeling prevents it from being a cheerful, hearty holiday; though every year makes it more so.\" In Reading, Pennsylvania, a newspaper remarked in 1861, \"Even our presbyterian friends who have hitherto steadfastly ignored Christmas—threw open their church doors and assembled in force to celebrate the anniversary of the Savior's birth.\"",
"title": "History"
},
{
"paragraph_id": 32,
"text": "The First Congregational Church of Rockford, Illinois, \"although of genuine Puritan stock\", was 'preparing for a grand Christmas jubilee', a news correspondent reported in 1864. By 1860, fourteen states including several from New England had adopted Christmas as a legal holiday. In 1875, Louis Prang introduced the Christmas card to Americans. He has been called the \"father of the American Christmas card\". On June 28, 1870, Christmas was formally declared a United States federal holiday.",
"title": "History"
},
{
"paragraph_id": 33,
"text": "During the First World War and particularly (but not exclusively) in 1914, a series of informal truces took place for Christmas between opposing armies. The truces, which were organised spontaneously by fighting men, ranged from promises not to shoot (shouted at a distance in order to ease the pressure of war for the day) to friendly socializing, gift giving and even sport between enemies. These incidents became a well known and semi-mythologised part of popular memory. They have been described as a symbol of common humanity even in the darkest of situations and used to demonstrate to children the ideals of Christmas.",
"title": "History"
},
{
"paragraph_id": 34,
"text": "Up to the 1950s in the UK, many Christmas customs were restricted to the upper and middle classes. Most of the population had not yet adopted many Christmas rituals that later became popular, including Christmas trees. Christmas dinner would normally include beef or goose, not turkey as would later be common. Children would get fruit and sweets in their stocking rather than elaborate gifts. Full celebration of a family Christmas with all the trimmings only became widespread with increased prosperity from the 1950s. National papers were published on Christmas Day until 1912. Post was still delivered on Christmas Day until 1961. League football matches continued in Scotland until the 1970s while in England they ceased at the end of the 1950s.",
"title": "History"
},
{
"paragraph_id": 35,
"text": "Under the state atheism of the Soviet Union, after its foundation in 1917, Christmas celebrations—along with other Christian holidays—were prohibited in public. During the 1920s, 1930s, and 1940s, the League of Militant Atheists encouraged school pupils to campaign against Christmas traditions, such as the Christmas tree, as well as other Christian holidays, including Easter; the League established an antireligious holiday to be the 31st of each month as a replacement. At the height of this persecution, in 1929, on Christmas Day, children in Moscow were encouraged to spit on crucifixes as a protest against the holiday. Instead, the importance of the holiday and all its trappings, such as the Christmas tree and gift-giving, was transferred to the New Year. It was not until the dissolution of the Soviet Union in 1991 that the persecution ended and Orthodox Christmas became a state holiday again for the first time in Russia after seven decades.",
"title": "History"
},
{
"paragraph_id": 36,
"text": "European History Professor Joseph Perry wrote that likewise, in Nazi Germany, \"because Nazi ideologues saw organized religion as an enemy of the totalitarian state, propagandists sought to deemphasize—or eliminate altogether—the Christian aspects of the holiday\" and that \"Propagandists tirelessly promoted numerous Nazified Christmas songs, which replaced Christian themes with the regime's racial ideologies.\"",
"title": "History"
},
{
"paragraph_id": 37,
"text": "As Christmas celebrations began to spread globally even outside traditional Christian cultures, several Muslim-majority countries began to ban the observance of Christmas, claiming it undermined Islam. In 2023, public Christmas celebrations were cancelled in Bethlehem, the city synonymous with the birth of Jesus. Palestinian leaders of various Christian denominations cited the ongoing Israel–Hamas war in their unanimous decision to cancel celebrations.",
"title": "History"
},
{
"paragraph_id": 38,
"text": "Christmas Day is celebrated as a major festival and public holiday in countries around the world, including many whose populations are mostly non-Christian. In some non-Christian areas, periods of former colonial rule introduced the celebration (e.g. Hong Kong); in others, Christian minorities or foreign cultural influences have led populations to observe the holiday. Countries such as Japan, where Christmas is popular despite there being only a small number of Christians, have adopted many of the cultural aspects of Christmas, such as gift-giving, decorations, and Christmas trees. A similar example is in Turkey, being Muslim-majority and with a small number of Christians, where Christmas trees and decorations tend to line public streets during the festival.",
"title": "Observance and traditions"
},
{
"paragraph_id": 39,
"text": "Many popular customs associated with Christmas developed independently of the commemoration of Jesus's birth, with some claiming that certain elements are Christianized and have origins in pre-Christian festivals that were celebrated by pagan populations who were later converted to Christianity; other scholars reject these claims and affirm that Christmas customs largely developed in a Christian context. The prevailing atmosphere of Christmas has also continually evolved since the holiday's inception, ranging from a sometimes raucous, drunken, carnival-like state in the Middle Ages, to a tamer family-oriented and children-centered theme introduced in a 19th-century transformation. The celebration of Christmas was banned on more than one occasion within certain groups, such as the Puritans and Jehovah's Witnesses (who do not celebrate birthdays in general), due to concerns that it was too unbiblical.",
"title": "Observance and traditions"
},
{
"paragraph_id": 40,
"text": "Prior to and through the early Christian centuries, winter festivals were the most popular of the year in many European pagan cultures. Reasons included the fact that less agricultural work needed to be done during the winter, as well as an expectation of better weather as spring approached. Celtic winter herbs such as mistletoe and ivy, and the custom of kissing under a mistletoe, are common in modern Christmas celebrations in the English-speaking countries.",
"title": "Observance and traditions"
},
{
"paragraph_id": 41,
"text": "The pre-Christian Germanic peoples—including the Anglo-Saxons and the Norse—celebrated a winter festival called Yule, held in the late December to early January period, yielding modern English yule, today used as a synonym for Christmas. In Germanic language-speaking areas, numerous elements of modern Christmas folk custom and iconography may have originated from Yule, including the Yule log, Yule boar, and the Yule goat. Often leading a ghostly procession through the sky (the Wild Hunt), the long-bearded god Odin is referred to as \"the Yule one\" and \"Yule father\" in Old Norse texts, while other gods are referred to as \"Yule beings\". On the other hand, as there are no reliable existing references to a Christmas log prior to the 16th century, the burning of the Christmas block may have been an early modern invention by Christians unrelated to the pagan practice.",
"title": "Observance and traditions"
},
{
"paragraph_id": 42,
"text": "Among countries with a strong Christian tradition, a variety of Christmas celebrations have developed that incorporate regional and local cultures. For example, in eastern Europe Christmas celebrations incorporated pre-Christian traditions such as the Koleda, which shares parallels with the Christmas carol.",
"title": "Observance and traditions"
},
{
"paragraph_id": 43,
"text": "Christmas Day (inclusive of its vigil, Christmas Eve), is a Festival in the Lutheran Churches, a solemnity in the Roman Catholic Church, and a Principal Feast of the Anglican Communion. Other Christian denominations do not rank their feast days but nevertheless place importance on Christmas Eve/Christmas Day, as with other Christian feasts like Easter, Ascension Day, and Pentecost. As such, for Christians, attending a Christmas Eve or Christmas Day church service plays an important part in the recognition of the Christmas season. Christmas, along with Easter, is the period of highest annual church attendance. A 2010 survey by LifeWay Christian Resources found that six in ten Americans attend church services during this time. In the United Kingdom, the Church of England reported an estimated attendance of 2.5 million people at Christmas services in 2015.",
"title": "Observance and traditions"
},
{
"paragraph_id": 44,
"text": "Nativity scenes are known from 10th-century Rome. They were popularised by Saint Francis of Assisi from 1223, quickly spreading across Europe. Different types of decorations developed across the Christian world, dependent on local tradition and available resources, and can vary from simple representations of the crib to far more elaborate sets – renowned manger scene traditions include the colourful Kraków szopka in Poland, which imitate Kraków's historical buildings as settings, the elaborate Italian presepi (Neapolitan, Genoese and Bolognese), or the Provençal crèches in southern France, using hand-painted terracotta figurines called santons. In certain parts of the world, notably Sicily, living nativity scenes following the tradition of Saint Francis are a popular alternative to static crèches. The first commercially produced decorations appeared in Germany in the 1860s, inspired by paper chains made by children. In countries where a representation of the Nativity scene is very popular, people are encouraged to compete and create the most original or realistic ones. Within some families, the pieces used to make the representation are considered a valuable family heirloom.",
"title": "Observance and traditions"
},
{
"paragraph_id": 45,
"text": "The traditional colors of Christmas decorations are red, green, and gold. Red symbolizes the blood of Jesus, which was shed in his crucifixion; green symbolizes eternal life, and in particular the evergreen tree, which does not lose its leaves in the winter; and gold is the first color associated with Christmas, as one of the three gifts of the Magi, symbolizing royalty.",
"title": "Observance and traditions"
},
{
"paragraph_id": 46,
"text": "The Christmas tree was first used by German Lutherans in the 16th century, with records indicating that a Christmas tree was placed in the Cathedral of Strassburg in 1539, under the leadership of the Protestant Reformer, Martin Bucer. In the United States, these \"German Lutherans brought the decorated Christmas tree with them; the Moravians put lighted candles on those trees.\" When decorating the Christmas tree, many individuals place a star at the top of the tree symbolizing the Star of Bethlehem, a fact recorded by The School Journal in 1897. Professor David Albert Jones of Oxford University writes that in the 19th century, it became popular for people to also use an angel to top the Christmas tree in order to symbolize the angels mentioned in the accounts of the Nativity of Jesus. Additionally, in the context of a Christian celebration of Christmas, the Christmas tree, being evergreen in colour, is symbolic of Christ, who offers eternal life; the candles or lights on the tree represent the Light of the World—Jesus—born in Bethlehem. Christian services for family use and public worship have been published for the blessing of a Christmas tree, after it has been erected. The Christmas tree is considered by some as Christianisation of pagan tradition and ritual surrounding the Winter Solstice, which included the use of evergreen boughs, and an adaptation of pagan tree worship; according to eighth-century biographer Æddi Stephanus, Saint Boniface (634–709), who was a missionary in Germany, took an ax to an oak tree dedicated to Thor and pointed out a fir tree, which he stated was a more fitting object of reverence because it pointed to heaven and it had a triangular shape, which he said was symbolic of the Trinity. The English language phrase \"Christmas tree\" is first recorded in 1835 and represents an importation from the German language.",
"title": "Observance and traditions"
},
{
"paragraph_id": 47,
"text": "Since the 16th century, the poinsettia, a native plant from Mexico, has been associated with Christmas carrying the Christian symbolism of the Star of Bethlehem; in that country it is known in Spanish as the Flower of the Holy Night. Other popular holiday plants include holly, mistletoe, red amaryllis, and Christmas cactus.",
"title": "Observance and traditions"
},
{
"paragraph_id": 48,
"text": "Other traditional decorations include bells, candles, candy canes, stockings, wreaths, and angels. Both the displaying of wreaths and candles in each window are a more traditional Christmas display. The concentric assortment of leaves, usually from an evergreen, make up Christmas wreaths and are designed to prepare Christians for the Advent season. Candles in each window are meant to demonstrate the fact that Christians believe that Jesus Christ is the ultimate light of the world.",
"title": "Observance and traditions"
},
{
"paragraph_id": 49,
"text": "Christmas lights and banners may be hung along streets, music played from speakers, and Christmas trees placed in prominent places. It is common in many parts of the world for town squares and consumer shopping areas to sponsor and display decorations. Rolls of brightly colored paper with secular or religious Christmas motifs are manufactured for the purpose of wrapping gifts. In some countries, Christmas decorations are traditionally taken down on Twelfth Night.",
"title": "Observance and traditions"
},
{
"paragraph_id": 50,
"text": "For the Christian celebration of Christmas, the viewing of the Nativity play is one of the oldest Christmastime traditions, with the first reenactment of the Nativity of Jesus taking place in 1223 AD. In that year, Francis of Assisi assembled a Nativity scene outside of his church in Italy and children sung Christmas carols celebrating the birth of Jesus. Each year, this grew larger and people travelled from afar to see Francis's depiction of the Nativity of Jesus that came to feature drama and music. Nativity plays eventually spread throughout all of Europe, where they remain popular. Christmas Eve and Christmas Day church services often came to feature Nativity plays, as did schools and theatres. In France, Germany, Mexico and Spain, Nativity plays are often reenacted outdoors in the streets.",
"title": "Observance and traditions"
},
{
"paragraph_id": 51,
"text": "The earliest extant specifically Christmas hymns appear in fourth-century Rome. Latin hymns such as \"Veni redemptor gentium\", written by Ambrose, Archbishop of Milan, were austere statements of the theological doctrine of the Incarnation in opposition to Arianism. \"Corde natus ex Parentis\" (\"Of the Father's love begotten\") by the Spanish poet Prudentius (died 413) is still sung in some churches today. In the 9th and 10th centuries, the Christmas \"Sequence\" or \"Prose\" was introduced in North European monasteries, developing under Bernard of Clairvaux into a sequence of rhymed stanzas. In the 12th century the Parisian monk Adam of St. Victor began to derive music from popular songs, introducing something closer to the traditional Christmas carol. Christmas carols in English appear in a 1426 work of John Awdlay who lists twenty five \"caroles of Cristemas\", probably sung by groups of 'wassailers', who went from house to house.",
"title": "Observance and traditions"
},
{
"paragraph_id": 52,
"text": "The songs now known specifically as carols were originally communal folk songs sung during celebrations such as \"harvest tide\" as well as Christmas. It was only later that carols began to be sung in church. Traditionally, carols have often been based on medieval chord patterns, and it is this that gives them their uniquely characteristic musical sound. Some carols like \"Personent hodie\", \"Good King Wenceslas\", and \"In dulci jubilo\" can be traced directly back to the Middle Ages. They are among the oldest musical compositions still regularly sung. \"Adeste Fideles\" (O Come all ye faithful) appeared in its current form in the mid-18th century.",
"title": "Observance and traditions"
},
{
"paragraph_id": 53,
"text": "The singing of carols increased in popularity after the Protestant Reformation in the Lutheran areas of Europe, as the Reformer Martin Luther wrote carols and encouraged their use in worship, in addition to spearheading the practice of caroling outside the Mass. The 18th-century English reformer Charles Wesley, a founder of Methodism, understood the importance of music to Christian worship. In addition to setting many psalms to melodies, he wrote texts for at least three Christmas carols. The best known was originally entitled \"Hark! How All the Welkin Rings\", later renamed \"Hark! The Herald Angels Sing\".",
"title": "Observance and traditions"
},
{
"paragraph_id": 54,
"text": "Christmas seasonal songs of a nonreligious nature emerged in the late 18th century. The Welsh melody for \"Deck the Halls\" dates from 1794, with the lyrics added by Scottish musician Thomas Oliphant in 1862, and the American \"Jingle Bells\" was copyrighted in 1857. Other popular carols include \"The First Noel\", \"God Rest You Merry, Gentlemen\", \"The Holly and the Ivy\", \"I Saw Three Ships\", \"In the Bleak Midwinter\", \"Joy to the World\", \"Once in Royal David's City\" and \"While Shepherds Watched Their Flocks\". In the 19th and 20th centuries, African American spirituals and songs about Christmas, based in their tradition of spirituals, became more widely known. An increasing number of seasonal holiday songs were commercially produced in the 20th century, including jazz and blues variations. In addition, there was a revival of interest in early music, from groups singing folk music, such as The Revels, to performers of early medieval and classical music.",
"title": "Observance and traditions"
},
{
"paragraph_id": 55,
"text": "One of the most ubiquitous festive songs is \"We Wish You a Merry Christmas\", which originates from the West Country of England in the 1930s. Radio has covered Christmas music from variety shows from the 1940s and 1950s, as well as modern-day stations that exclusively play Christmas music from late November through December 25. Hollywood movies have featured new Christmas music, such as \"White Christmas\" in Holiday Inn and Rudolph the Red-Nosed Reindeer. Traditional carols have also been included in Hollywood films, such as \"Hark! The Herald Angels Sing\" in It's a Wonderful Life (1946), and \"Silent Night\" in A Christmas Story.",
"title": "Observance and traditions"
},
{
"paragraph_id": 56,
"text": "A special Christmas family meal is traditionally an important part of the holiday's celebration, and the food that is served varies greatly from country to country. Some regions have special meals for Christmas Eve, such as Sicily, where 12 kinds of fish are served. In the United Kingdom and countries influenced by its traditions, a standard Christmas meal includes turkey, goose or other large bird, gravy, potatoes, vegetables, sometimes bread and cider. Special desserts are also prepared, such as Christmas pudding, mince pies, Christmas cake, Panettone and Yule log cake. A traditional Christmas meal in Central Europe features fried carp or other fish.",
"title": "Observance and traditions"
},
{
"paragraph_id": 57,
"text": "Christmas cards are illustrated messages of greeting exchanged between friends and family members during the weeks preceding Christmas Day. The traditional greeting reads \"wishing you a Merry Christmas and a Happy New Year\", much like that of the first commercial Christmas card, produced by Sir Henry Cole in London in 1843. The custom of sending them has become popular among a wide cross-section of people with the emergence of the modern trend towards exchanging E-cards.",
"title": "Observance and traditions"
},
{
"paragraph_id": 58,
"text": "Christmas cards are purchased in considerable quantities and feature artwork, commercially designed and relevant to the season. The content of the design might relate directly to the Christmas narrative, with depictions of the Nativity of Jesus, or Christian symbols such as the Star of Bethlehem, or a white dove, which can represent both the Holy Spirit and Peace on Earth. Other Christmas cards are more secular and can depict Christmas traditions, mythical figures such as Santa Claus, objects directly associated with Christmas such as candles, holly, and baubles, or a variety of images associated with the season, such as Christmastide activities, snow scenes, and the wildlife of the northern winter.",
"title": "Observance and traditions"
},
{
"paragraph_id": 59,
"text": "Some prefer cards with a poem, prayer, or Biblical verse; while others distance themselves from religion with an all-inclusive \"Season's greetings\".",
"title": "Observance and traditions"
},
{
"paragraph_id": 60,
"text": "A number of nations have issued commemorative stamps at Christmastide. Postal customers will often use these stamps to mail Christmas cards, and they are popular with philatelists. These stamps are regular postage stamps, unlike Christmas seals, and are valid for postage year-round. They usually go on sale sometime between early October and early December and are printed in considerable quantities.",
"title": "Observance and traditions"
},
{
"paragraph_id": 61,
"text": "The exchanging of gifts is one of the core aspects of the modern Christmas celebration, making it the most profitable time of year for retailers and businesses throughout the world. On Christmas, people exchange gifts based on the Christian tradition associated with Saint Nicholas, and the gifts of gold, frankincense, and myrrh which were given to the baby Jesus by the Magi. The practice of gift giving in the Roman celebration of Saturnalia may have influenced Christian customs, but on the other hand the Christian \"core dogma of the Incarnation, however, solidly established the giving and receiving of gifts as the structural principle of that recurrent yet unique event\", because it was the Biblical Magi, \"together with all their fellow men, who received the gift of God through man's renewed participation in the divine life.\" However, Thomas J. Talley holds that the Roman Emperor Aurelian placed the alternate festival on December 25 in order to compete with the growing rate of the Christian Church, which had already been celebrating Christmas on that date first.",
"title": "Observance and traditions"
},
{
"paragraph_id": 62,
"text": "A number of figures are associated with Christmas and the seasonal giving of gifts. Among these are Father Christmas, also known as Santa Claus (derived from the Dutch for Saint Nicholas), Père Noël, and the Weihnachtsmann; Saint Nicholas or Sinterklaas; the Christkind; Kris Kringle; Joulupukki; tomte/nisse; Babbo Natale; Saint Basil; and Ded Moroz. The Scandinavian tomte (also called nisse) is sometimes depicted as a gnome instead of Santa Claus.",
"title": "Observance and traditions"
},
{
"paragraph_id": 63,
"text": "The best known of these figures today is red-dressed Santa Claus, of diverse origins. The name 'Santa Claus' can be traced back to the Dutch Sinterklaas ('Saint Nicholas'). Nicholas was a 4th-century Greek bishop of Myra, a city in the Roman province of Lycia, whose ruins are 3 kilometres (1.9 mi) from modern Demre in southwest Turkey. Among other saintly attributes, he was noted for the care of children, generosity, and the giving of gifts. His feast day, December 6, came to be celebrated in many countries with the giving of gifts.",
"title": "Observance and traditions"
},
{
"paragraph_id": 64,
"text": "Saint Nicholas traditionally appeared in bishop's attire, accompanied by helpers, inquiring about the behaviour of children during the past year before deciding whether they deserved a gift or not. By the 13th century, Saint Nicholas was well known in the Netherlands, and the practice of gift-giving in his name spread to other parts of central and southern Europe. At the Reformation in 16th- and 17th-century Europe, many Protestants changed the gift bringer to the Christ Child or Christkindl, corrupted in English to 'Kris Kringle', and the date of giving gifts changed from December 6 to Christmas Eve.",
"title": "Observance and traditions"
},
{
"paragraph_id": 65,
"text": "The modern popular image of Santa Claus, however, was created in the United States, and in particular in New York. The transformation was accomplished with the aid of notable contributors including Washington Irving and the German-American cartoonist Thomas Nast (1840–1902). Following the American Revolutionary War, some of the inhabitants of New York City sought out symbols of the city's non-English past. New York had originally been established as the Dutch colonial town of New Amsterdam and the Dutch Sinterklaas tradition was reinvented as Saint Nicholas.",
"title": "Observance and traditions"
},
{
"paragraph_id": 66,
"text": "Current tradition in several Latin American countries (such as Venezuela and Colombia) holds that while Santa makes the toys, he then gives them to the Baby Jesus, who is the one who actually delivers them to the children's homes, a reconciliation between traditional religious beliefs and the iconography of Santa Claus imported from the United States.",
"title": "Observance and traditions"
},
{
"paragraph_id": 67,
"text": "In Italy's South Tyrol, Austria, the Czech Republic, Southern Germany, Hungary, Liechtenstein, Slovakia, and Switzerland, the Christkind (Ježíšek in Czech, Jézuska in Hungarian and Ježiško in Slovak) brings the presents. Greek children get their presents from Saint Basil on New Year's Eve, the eve of that saint's liturgical feast. The German St. Nikolaus is not identical with the Weihnachtsmann (who is the German version of Santa Claus / Father Christmas). St. Nikolaus wears a bishop's dress and still brings small gifts (usually candies, nuts, and fruits) on December 6 and is accompanied by Knecht Ruprecht. Although many parents around the world routinely teach their children about Santa Claus and other gift bringers, some have come to reject this practice, considering it deceptive.",
"title": "Observance and traditions"
},
{
"paragraph_id": 68,
"text": "Multiple gift-giver figures exist in Poland, varying between regions and individual families. St Nicholas (Święty Mikołaj) dominates Central and North-East areas, the Starman (Gwiazdor) is most common in Greater Poland, Baby Jesus (Dzieciątko) is unique to Upper Silesia, with the Little Star (Gwiazdka) and the Little Angel (Aniołek) being common in the South and the South-East. Grandfather Frost (Dziadek Mróz) is less commonly accepted in some areas of Eastern Poland. It is worth noting that across all of Poland, St Nicholas is the gift giver on Saint Nicholas Day on December 6.",
"title": "Observance and traditions"
},
{
"paragraph_id": 69,
"text": "Christmas during the Middle Ages was a public festival with annual indulgences included the sporting. When Puritans outlawed Christmas in England in December 1647 the crowd brought out footballs as a symbol of festive misrule. The Orkney Christmas Day Ba' tradition continues. In the former top tier of English football, home and away Christmas Day and Boxing Day double headers were often played guaranteeing football clubs large crowds by allowing many working people their only chance to watch a game. Champions Preston North End faced Aston Villa on Christmas Day 1889 and the last 25 December fixture was in 1965 in England, Blackpool beating Blackburn Rovers 4–2. One of the most memorable images of the Christmas truce during World War I was the games of football played between the opposing sides on Christmas Day 1914.",
"title": "Observance and traditions"
},
{
"paragraph_id": 70,
"text": "More recently, in the United States, both NFL and NBA have held fixtures on Christmas Day.",
"title": "Observance and traditions"
},
{
"paragraph_id": 71,
"text": "There are two main theories behind December 25 becoming the traditional date for Christmas, although Theology professor Susan Roll says that \"No liturgical historian [...] goes so far as to deny that it has any sort of relation with the sun, the winter solstice and the popularity of solar worship in the later Roman Empire\". December 25 was the date of the winter solstice in the Roman calendar. Some early Christian writers noted the solar symbolism in placing Jesus's birthday at the winter solstice and John's birthday at the summer solstice.",
"title": "Choice of date"
},
{
"paragraph_id": 72,
"text": "The 'history of religions' theory suggests the Church chose December 25 as Christ's birthday (dies Natalis Christi) to appropriate the Roman winter solstice festival dies Natalis Solis Invicti (birthday of Sol Invictus, the 'Invincible Sun'), held on this date since 274 AD. The early Church linked Jesus Christ to the Sun and referred to him as the 'Sun of Righteousness' (Sol Justitiae) prophesied by Malachi. Gary Forsythe, Professor of Ancient History, says that the Natalis Solis Invicti followed \"the seven-day period of the Saturnalia (December 17–23), Rome's most joyous holiday season since Republican times, characterized by parties, banquets, and exchanges of gifts\".",
"title": "Choice of date"
},
{
"paragraph_id": 73,
"text": "Another theory, the 'computation hypothesis' or 'calculation theory', notes that December 25 is nine months after March 25, a date chosen as Jesus's conception (the Annunciation) and the date of the spring equinox on the Roman calendar.",
"title": "Choice of date"
},
{
"paragraph_id": 74,
"text": "Some jurisdictions of the Eastern Orthodox Church, including those of Russia, Georgia, Macedonia, Montenegro, Serbia, and Jerusalem, mark feasts using the older Julian calendar. As of 2023, there is a difference of 13 days between the Julian calendar and the modern Gregorian calendar, which is used internationally for most secular purposes. As a result, December 25 on the Julian calendar currently corresponds to January 7 on the calendar used by most governments and people in everyday life. Therefore, the aforementioned Orthodox Christians mark December 25 (and thus Christmas) on the day that is internationally considered to be January 7.",
"title": "Choice of date"
},
{
"paragraph_id": 75,
"text": "However, following the Council of Constantinople in 1923, other Orthodox Christians, such as those belonging to the jurisdictions of Constantinople, Bulgaria, Greece, Romania, Antioch, Alexandria, Albania, Cyprus, Finland, and the Orthodox Church in America, among others, began using the Revised Julian calendar, which at present corresponds exactly to the Gregorian calendar. Therefore, these Orthodox Christians mark December 25 (and thus Christmas) on the same day that is internationally considered to be December 25.",
"title": "Choice of date"
},
{
"paragraph_id": 76,
"text": "A further complication is added by the fact that the Armenian Apostolic Church continues the original ancient Eastern Christian practice of celebrating the birth of Christ not as a separate holiday, but on the same day as the celebration of his baptism (Theophany), which is on January 6. This is a public holiday in Armenia, and it is held on the same day that is internationally considered to be January 6, because since 1923 the Armenian Church in Armenia has used the Gregorian calendar.",
"title": "Choice of date"
},
{
"paragraph_id": 77,
"text": "However, there is also a small Armenian Patriarchate of Jerusalem, which maintains the traditional Armenian custom of celebrating the birth of Christ on the same day as Theophany (January 6), but uses the Julian calendar for the determination of that date. As a result, this church celebrates \"Christmas\" (more properly called Theophany) on the day that is considered January 19 on the Gregorian calendar in use by the majority of the world.",
"title": "Choice of date"
},
{
"paragraph_id": 78,
"text": "Following the 2022 invasion of its territory by Russia, Ukraine officially moved its Christmas date from January 7 to December 25, to distance itself from the Russian Orthodox Church that had supported Russia's invasion. This followed the Orthodox Church of Ukraine formally adopting the Revised Julian calendar for fixed feasts and solemnities.",
"title": "Choice of date"
},
{
"paragraph_id": 79,
"text": "There are four different dates used by different Christian groups to mark the birth of Christ, given in the table below.",
"title": "Choice of date"
},
{
"paragraph_id": 80,
"text": "Christmas is typically a peak selling season for retailers in many nations around the world. Sales increase dramatically as people purchase gifts, decorations, and supplies to celebrate. In the United States, the \"Christmas shopping season\" starts as early as October. In Canada, merchants begin advertising campaigns just before Halloween (October 31), and step up their marketing following Remembrance Day on November 11. In the UK and Ireland, the Christmas shopping season starts from mid-November, around the time when high street Christmas lights are turned on. In the United States, it has been calculated that a quarter of all personal spending takes place during the Christmas/holiday shopping season. Figures from the U.S. Census Bureau reveal that expenditure in department stores nationwide rose from $20.8 billion in November 2004 to $31.9 billion in December 2004, an increase of 54 percent. In other sectors, the pre-Christmas increase in spending was even greater, there being a November–December buying surge of 100 percent in bookstores and 170 percent in jewelry stores. In the same year employment in American retail stores rose from 1.6 million to 1.8 million in the two months leading up to Christmas. Industries completely dependent on Christmas include Christmas cards, of which 1.9 billion are sent in the United States each year, and live Christmas trees, of which 20.8 million were cut in the U.S. in 2002. For 2019, the average US adult was projected to spend $920 on gifts alone. In the UK in 2010, up to £8 billion was expected to be spent online at Christmas, approximately a quarter of total retail festive sales.",
"title": "Economy"
},
{
"paragraph_id": 81,
"text": "In most Western nations, Christmas Day is the least active day of the year for business and commerce; almost all retail, commercial and institutional businesses are closed, and almost all industries cease activity (more than any other day of the year), whether laws require such or not. In England and Wales, the Christmas Day (Trading) Act 2004 prevents all large shops from trading on Christmas Day. Similar legislation was approved in Scotland in 2007. Film studios release many high-budget movies during the holiday season, including Christmas films, fantasy movies or high-tone dramas with high production values to hopes of maximizing the chance of nominations for the Academy Awards.",
"title": "Economy"
},
{
"paragraph_id": 82,
"text": "One economist's analysis calculates that, despite increased overall spending, Christmas is a deadweight loss under orthodox microeconomic theory, because of the effect of gift-giving. This loss is calculated as the difference between what the gift giver spent on the item and what the gift receiver would have paid for the item. It is estimated that in 2001, Christmas resulted in a $4 billion deadweight loss in the U.S. alone. Because of complicating factors, this analysis is sometimes used to discuss possible flaws in current microeconomic theory. Other deadweight losses include the effects of Christmas on the environment and the fact that material gifts are often perceived as white elephants, imposing cost for upkeep and storage and contributing to clutter.",
"title": "Economy"
},
{
"paragraph_id": 83,
"text": "Christmas has at times been the subject of controversy and attacks from various sources, both Christian and non-Christian. Historically, it was prohibited by Puritans during their ascendency in the Commonwealth of England (1647–1660), and in Colonial New England where the Puritans outlawed the celebration of Christmas in 1659 on the grounds that Christmas was not mentioned in Scripture and therefore violated the Reformed regulative principle of worship. The Parliament of Scotland, which was dominated by Presbyterians, passed a series of acts outlawing the observance of Christmas between 1637 and 1690; Christmas Day did not become a public holiday in Scotland until 1871. Today, some conservative Reformed denominations such as the Free Presbyterian Church of Scotland and the Reformed Presbyterian Church of North America likewise reject the celebration of Christmas based on the regulative principle and what they see as its non-Scriptural origin. Christmas celebrations have also been prohibited by atheist states such as the Soviet Union and more recently majority Muslim states such as Somalia, Tajikistan and Brunei.",
"title": "Controversies"
},
{
"paragraph_id": 84,
"text": "Some Christians and organizations such as Pat Robertson's American Center for Law and Justice cite alleged attacks on Christmas (dubbing them a \"war on Christmas\"). Such groups claim that any specific mention of the term \"Christmas\" or its religious aspects is being increasingly censored, avoided, or discouraged by a number of advertisers, retailers, government (prominently schools), and other public and private organizations. One controversy is the occurrence of Christmas trees being renamed Holiday trees. In the U.S. there has been a tendency to replace the greeting Merry Christmas with Happy Holidays, which is considered inclusive at the time of the Jewish celebration of Hanukkah. In the U.S. and Canada, where the use of the term \"Holidays\" is most prevalent, opponents have denounced its usage and avoidance of using the term \"Christmas\" as being politically correct. In 1984, the U.S. Supreme Court ruled in Lynch v. Donnelly that a Christmas display (which included a Nativity scene) owned and displayed by the city of Pawtucket, Rhode Island, did not violate the First Amendment. American Muslim scholar Abdul Malik Mujahid has said that Muslims must treat Christmas with respect, even if they disagree with it.",
"title": "Controversies"
},
{
"paragraph_id": 85,
"text": "The government of the People's Republic of China officially espouses state atheism, and has conducted antireligious campaigns to this end. In December 2018, officials raided Christian churches prior to Christmastide and coerced them to close; Christmas trees and Santa Clauses were also forcibly removed.",
"title": "Controversies"
}
] | Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25 as a religious and cultural celebration among billions of people around the world. A feast central to the liturgical year in Christianity, it follows the season of Advent or the Nativity Fast, and initiates the season of Christmastide, which historically in the West lasts twelve days and culminates on Twelfth Night. Christmas Day is a public holiday in many countries, is celebrated religiously by a majority of Christians, as well as culturally by many non-Christians, and forms an integral part of the holiday season surrounding it. The traditional Christmas narrative recounted in the New Testament, known as the Nativity of Jesus, says that Jesus was born in Bethlehem, in accordance with messianic prophecies. When Joseph and Mary arrived in the city, the inn had no room, and so they were offered a stable where the Christ Child was soon born, with angels proclaiming this news to shepherds, who then spread the word. There are different hypotheses regarding the date of Jesus's birth, and in the early fourth century, the church fixed the date as December 25. This corresponds to the traditional date of the winter solstice on the Roman calendar. It is exactly nine months after Annunciation on March 25, also the date of the spring equinox. Most Christians celebrate on December 25 in the Gregorian calendar, which has been adopted almost universally in the civil calendars used in countries throughout the world. However, part of the Eastern Christian Churches celebrate Christmas on December 25 of the older Julian calendar, which currently corresponds to January 7 in the Gregorian calendar. For Christians, believing that God came into the world in the form of man to atone for the sins of humanity rather than knowing Jesus's exact birth date is considered to be the primary purpose of celebrating Christmas. The customs associated with Christmas in various countries have a mix of pre-Christian, Christian, and secular themes and origins. Popular holiday traditions include gift giving; completing an Advent calendar or Advent wreath; Christmas music and caroling; watching Christmas movies; viewing a Nativity play; an exchange of Christmas cards; attending church services; a special meal; and displaying various Christmas decorations, including Christmas trees, Christmas lights, nativity scenes, garlands, wreaths, mistletoe, and holly. Additionally, several related and often interchangeable figures, known as Santa Claus, Father Christmas, Saint Nicholas, and Christkind, are associated with bringing gifts to children during the Christmas season and have their own body of traditions and lore. Because gift-giving and many other aspects of the Christmas festival involve heightened economic activity, the holiday has become a significant event and a key sales period for retailers and businesses. Over the past few centuries, Christmas has had a steadily growing economic effect in many regions of the world. | 2001-10-31T22:55:45Z | 2023-12-28T16:58:05Z | [
"Template:Efn",
"Template:Lang",
"Template:Convert",
"Template:Cite web",
"Template:Short description",
"Template:Pp",
"Template:Cite journal",
"Template:Christmas",
"Template:Bibleverse",
"Template:Cite EB1911",
"Template:Currentyear",
"Template:Portal",
"Template:Annotated link",
"Template:Reflist",
"Template:ISBN",
"Template:Cite magazine",
"Template:Virgin Mary",
"Template:Infobox holiday",
"Template:See also",
"Template:Transliteration",
"Template:Citation needed",
"Template:Webarchive",
"Template:Nativity of Jesus",
"Template:Navboxes",
"Template:C.",
"Template:Abbr",
"Template:Listen",
"Template:Cite AV media",
"Template:Cbignore",
"Template:Refend",
"Template:Cite press release",
"Template:Jesus footer",
"Template:Other uses",
"Template:Redirect",
"Template:Main",
"Template:Ill",
"Template:Notelist",
"Template:Cite news",
"Template:Refbegin",
"Template:Cite Catholic Encyclopedia",
"Template:Use mdy dates",
"Template:TOC limit",
"Template:Further",
"Template:Nbsp",
"Template:Cite encyclopedia",
"Template:Cite speech",
"Template:Sister project links",
"Template:Cite book",
"Template:Authority control"
] | https://en.wikipedia.org/wiki/Christmas |
6,239 | Contraction mapping | In mathematics, a contraction mapping, or contraction or contractor, on a metric space (M, d) is a function f from M to itself, with the property that there is some real number 0 ≤ k < 1 {\displaystyle 0\leq k<1} such that for all x and y in M,
The smallest such value of k is called the Lipschitz constant of f. Contractive maps are sometimes called Lipschitzian maps. If the above condition is instead satisfied for k ≤ 1, then the mapping is said to be a non-expansive map.
More generally, the idea of a contractive mapping can be defined for maps between metric spaces. Thus, if (M, d) and (N, d') are two metric spaces, then f : M → N {\displaystyle f:M\rightarrow N} is a contractive mapping if there is a constant 0 ≤ k < 1 {\displaystyle 0\leq k<1} such that
for all x and y in M.
Every contraction mapping is Lipschitz continuous and hence uniformly continuous (for a Lipschitz continuous function, the constant k is no longer necessarily less than 1).
A contraction mapping has at most one fixed point. Moreover, the Banach fixed-point theorem states that every contraction mapping on a non-empty complete metric space has a unique fixed point, and that for any x in M the iterated function sequence x, f (x), f (f (x)), f (f (f (x))), ... converges to the fixed point. This concept is very useful for iterated function systems where contraction mappings are often used. Banach's fixed-point theorem is also applied in proving the existence of solutions of ordinary differential equations, and is used in one proof of the inverse function theorem.
Contraction mappings play an important role in dynamic programming problems.
A non-expansive mapping with k = 1 {\displaystyle k=1} can be generalized to a firmly non-expansive mapping in a Hilbert space H {\displaystyle {\mathcal {H}}} if the following holds for all x and y in H {\displaystyle {\mathcal {H}}} :
where
This is a special case of α {\displaystyle \alpha } averaged nonexpansive operators with α = 1 / 2 {\displaystyle \alpha =1/2} . A firmly non-expansive mapping is always non-expansive, via the Cauchy–Schwarz inequality.
The class of firmly non-expansive maps is closed under convex combinations, but not compositions. This class includes proximal mappings of proper, convex, lower-semicontinuous functions, hence it also includes orthogonal projections onto non-empty closed convex sets. The class of firmly nonexpansive operators is equal to the set of resolvents of maximally monotone operators. Surprisingly, while iterating non-expansive maps has no guarantee to find a fixed point (e.g. multiplication by -1), firm non-expansiveness is sufficient to guarantee global convergence to a fixed point, provided a fixed point exists. More precisely, if Fix f := { x ∈ H | f ( x ) = x } ≠ ∅ {\displaystyle {\text{Fix}}f:=\{x\in {\mathcal {H}}\ |\ f(x)=x\}\neq \varnothing } , then for any initial point x 0 ∈ H {\displaystyle x_{0}\in {\mathcal {H}}} , iterating
( ∀ n ∈ N ) x n + 1 = f ( x n ) {\displaystyle (\forall n\in \mathbb {N} )\quad x_{n+1}=f(x_{n})}
yields convergence to a fixed point x n → z ∈ Fix f {\displaystyle x_{n}\to z\in {\text{Fix}}f} . This convergence might be weak in an infinite-dimensional setting.
A subcontraction map or subcontractor is a map f on a metric space (M, d) such that
If the image of a subcontractor f is compact, then f has a fixed point.
In a locally convex space (E, P) with topology given by a set P of seminorms, one can define for any p ∈ P a p-contraction as a map f such that there is some kp < 1 such that p(f(x) − f(y)) ≤ kp p(x − y). If f is a p-contraction for all p ∈ P and (E, P) is sequentially complete, then f has a fixed point, given as limit of any sequence xn+1 = f(xn), and if (E, P) is Hausdorff, then the fixed point is unique. | [
{
"paragraph_id": 0,
"text": "In mathematics, a contraction mapping, or contraction or contractor, on a metric space (M, d) is a function f from M to itself, with the property that there is some real number 0 ≤ k < 1 {\\displaystyle 0\\leq k<1} such that for all x and y in M,",
"title": ""
},
{
"paragraph_id": 1,
"text": "The smallest such value of k is called the Lipschitz constant of f. Contractive maps are sometimes called Lipschitzian maps. If the above condition is instead satisfied for k ≤ 1, then the mapping is said to be a non-expansive map.",
"title": ""
},
{
"paragraph_id": 2,
"text": "More generally, the idea of a contractive mapping can be defined for maps between metric spaces. Thus, if (M, d) and (N, d') are two metric spaces, then f : M → N {\\displaystyle f:M\\rightarrow N} is a contractive mapping if there is a constant 0 ≤ k < 1 {\\displaystyle 0\\leq k<1} such that",
"title": ""
},
{
"paragraph_id": 3,
"text": "for all x and y in M.",
"title": ""
},
{
"paragraph_id": 4,
"text": "Every contraction mapping is Lipschitz continuous and hence uniformly continuous (for a Lipschitz continuous function, the constant k is no longer necessarily less than 1).",
"title": ""
},
{
"paragraph_id": 5,
"text": "A contraction mapping has at most one fixed point. Moreover, the Banach fixed-point theorem states that every contraction mapping on a non-empty complete metric space has a unique fixed point, and that for any x in M the iterated function sequence x, f (x), f (f (x)), f (f (f (x))), ... converges to the fixed point. This concept is very useful for iterated function systems where contraction mappings are often used. Banach's fixed-point theorem is also applied in proving the existence of solutions of ordinary differential equations, and is used in one proof of the inverse function theorem.",
"title": ""
},
{
"paragraph_id": 6,
"text": "Contraction mappings play an important role in dynamic programming problems.",
"title": ""
},
{
"paragraph_id": 7,
"text": "A non-expansive mapping with k = 1 {\\displaystyle k=1} can be generalized to a firmly non-expansive mapping in a Hilbert space H {\\displaystyle {\\mathcal {H}}} if the following holds for all x and y in H {\\displaystyle {\\mathcal {H}}} :",
"title": "Firmly non-expansive mapping"
},
{
"paragraph_id": 8,
"text": "where",
"title": "Firmly non-expansive mapping"
},
{
"paragraph_id": 9,
"text": "This is a special case of α {\\displaystyle \\alpha } averaged nonexpansive operators with α = 1 / 2 {\\displaystyle \\alpha =1/2} . A firmly non-expansive mapping is always non-expansive, via the Cauchy–Schwarz inequality.",
"title": "Firmly non-expansive mapping"
},
{
"paragraph_id": 10,
"text": "The class of firmly non-expansive maps is closed under convex combinations, but not compositions. This class includes proximal mappings of proper, convex, lower-semicontinuous functions, hence it also includes orthogonal projections onto non-empty closed convex sets. The class of firmly nonexpansive operators is equal to the set of resolvents of maximally monotone operators. Surprisingly, while iterating non-expansive maps has no guarantee to find a fixed point (e.g. multiplication by -1), firm non-expansiveness is sufficient to guarantee global convergence to a fixed point, provided a fixed point exists. More precisely, if Fix f := { x ∈ H | f ( x ) = x } ≠ ∅ {\\displaystyle {\\text{Fix}}f:=\\{x\\in {\\mathcal {H}}\\ |\\ f(x)=x\\}\\neq \\varnothing } , then for any initial point x 0 ∈ H {\\displaystyle x_{0}\\in {\\mathcal {H}}} , iterating",
"title": "Firmly non-expansive mapping"
},
{
"paragraph_id": 11,
"text": "( ∀ n ∈ N ) x n + 1 = f ( x n ) {\\displaystyle (\\forall n\\in \\mathbb {N} )\\quad x_{n+1}=f(x_{n})}",
"title": "Firmly non-expansive mapping"
},
{
"paragraph_id": 12,
"text": "yields convergence to a fixed point x n → z ∈ Fix f {\\displaystyle x_{n}\\to z\\in {\\text{Fix}}f} . This convergence might be weak in an infinite-dimensional setting.",
"title": "Firmly non-expansive mapping"
},
{
"paragraph_id": 13,
"text": "A subcontraction map or subcontractor is a map f on a metric space (M, d) such that",
"title": "Subcontraction map"
},
{
"paragraph_id": 14,
"text": "If the image of a subcontractor f is compact, then f has a fixed point.",
"title": "Subcontraction map"
},
{
"paragraph_id": 15,
"text": "In a locally convex space (E, P) with topology given by a set P of seminorms, one can define for any p ∈ P a p-contraction as a map f such that there is some kp < 1 such that p(f(x) − f(y)) ≤ kp p(x − y). If f is a p-contraction for all p ∈ P and (E, P) is sequentially complete, then f has a fixed point, given as limit of any sequence xn+1 = f(xn), and if (E, P) is Hausdorff, then the fixed point is unique.",
"title": "Locally convex spaces"
}
] | In mathematics, a contraction mapping, or contraction or contractor, on a metric space (M, d) is a function f from M to itself, with the property that there is some real number 0 ≤ k < 1 such that for all x and y in M, The smallest such value of k is called the Lipschitz constant of f. Contractive maps are sometimes called Lipschitzian maps. If the above condition is instead satisfied for
k ≤ 1, then the mapping is said to be a non-expansive map. More generally, the idea of a contractive mapping can be defined for maps between metric spaces. Thus, if (M, d) and (N, d') are two metric spaces, then f : M → N is a contractive mapping if there is a constant 0 ≤ k < 1 such that for all x and y in M. Every contraction mapping is Lipschitz continuous and hence uniformly continuous (for a Lipschitz continuous function, the constant k is no longer necessarily less than 1). A contraction mapping has at most one fixed point. Moreover, the Banach fixed-point theorem states that every contraction mapping on a non-empty complete metric space has a unique fixed point, and that for any x in M the iterated function sequence x, f (x), f (f (x)), f (f (f (x))), ... converges to the fixed point. This concept is very useful for iterated function systems where contraction mappings are often used. Banach's fixed-point theorem is also applied in proving the existence of solutions of ordinary differential equations, and is used in one proof of the inverse function theorem. Contraction mappings play an important role in dynamic programming problems. | 2001-09-01T20:55:30Z | 2023-11-01T23:09:55Z | [
"Template:Short description",
"Template:Nowrap",
"Template:Reflist",
"Template:Cite book",
"Template:Cite journal"
] | https://en.wikipedia.org/wiki/Contraction_mapping |
6,246 | Covalent bond | A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding. For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full valence shell, corresponding to a stable electronic configuration. In organic chemistry, covalent bonding is much more common than ionic bonding.
Covalent bonding also includes many kinds of interactions, including σ-bonding, π-bonding, metal-to-metal bonding, agostic interactions, bent bonds, three-center two-electron bonds and three-center four-electron bonds. The term covalent bond dates from 1939. The prefix co- means jointly, associated in action, partnered to a lesser degree, etc.; thus a "co-valent bond", in essence, means that the atoms share "valence", such as is discussed in valence bond theory.
In the molecule H2, the hydrogen atoms share the two electrons via covalent bonding. Covalency is greatest between atoms of similar electronegativities. Thus, covalent bonding does not necessarily require that the two atoms be of the same elements, only that they be of comparable electronegativity. Covalent bonding that entails the sharing of electrons over more than two atoms is said to be delocalized.
The term covalence in regard to bonding was first used in 1919 by Irving Langmuir in a Journal of the American Chemical Society article entitled "The Arrangement of Electrons in Atoms and Molecules". Langmuir wrote that "we shall denote by the term covalence the number of pairs of electrons that a given atom shares with its neighbors."
The idea of covalent bonding can be traced several years before 1919 to Gilbert N. Lewis, who in 1916 described the sharing of electron pairs between atoms (and in 1926 he also coined the term "photon" for the smallest unit of radiant energy). He introduced the Lewis notation or electron dot notation or Lewis dot structure, in which valence electrons (those in the outer shell) are represented as dots around the atomic symbols. Pairs of electrons located between atoms represent covalent bonds. Multiple pairs represent multiple bonds, such as double bonds and triple bonds. An alternative form of representation, not shown here, has bond-forming electron pairs represented as solid lines.
Lewis proposed that an atom forms enough covalent bonds to form a full (or closed) outer electron shell. In the diagram of methane shown here, the carbon atom has a valence of four and is, therefore, surrounded by eight electrons (the octet rule), four from the carbon itself and four from the hydrogens bonded to it. Each hydrogen has a valence of one and is surrounded by two electrons (a duet rule) – its own one electron plus one from the carbon. The numbers of electrons correspond to full shells in the quantum theory of the atom; the outer shell of a carbon atom is the n = 2 shell, which can hold eight electrons, whereas the outer (and only) shell of a hydrogen atom is the n = 1 shell, which can hold only two.
While the idea of shared electron pairs provides an effective qualitative picture of covalent bonding, quantum mechanics is needed to understand the nature of these bonds and predict the structures and properties of simple molecules. Walter Heitler and Fritz London are credited with the first successful quantum mechanical explanation of a chemical bond (molecular hydrogen) in 1927. Their work was based on the valence bond model, which assumes that a chemical bond is formed when there is good overlap between the atomic orbitals of participating atoms.
Atomic orbitals (except for s orbitals) have specific directional properties leading to different types of covalent bonds. Sigma (σ) bonds are the strongest covalent bonds and are due to head-on overlapping of orbitals on two different atoms. A single bond is usually a σ bond. Pi (π) bonds are weaker and are due to lateral overlap between p (or d) orbitals. A double bond between two given atoms consists of one σ and one π bond, and a triple bond is one σ and two π bonds.
Covalent bonds are also affected by the electronegativity of the connected atoms which determines the chemical polarity of the bond. Two atoms with equal electronegativity will make nonpolar covalent bonds such as H–H. An unequal relationship creates a polar covalent bond such as with H−Cl. However polarity also requires geometric asymmetry, or else dipoles may cancel out, resulting in a non-polar molecule.
There are several types of structures for covalent substances, including individual molecules, molecular structures, macromolecular structures and giant covalent structures. Individual molecules have strong bonds that hold the atoms together, but generally, there are negligible forces of attraction between molecules. Such covalent substances are usually gases, for example, HCl, SO2, CO2, and CH4. In molecular structures, there are weak forces of attraction. Such covalent substances are low-boiling-temperature liquids (such as ethanol), and low-melting-temperature solids (such as iodine and solid CO2). Macromolecular structures have large numbers of atoms linked by covalent bonds in chains, including synthetic polymers such as polyethylene and nylon, and biopolymers such as proteins and starch. Network covalent structures (or giant covalent structures) contain large numbers of atoms linked in sheets (such as graphite), or 3-dimensional structures (such as diamond and quartz). These substances have high melting and boiling points, are frequently brittle, and tend to have high electrical resistivity. Elements that have high electronegativity, and the ability to form three or four electron pair bonds, often form such large macromolecular structures.
Bonds with one or three electrons can be found in radical species, which have an odd number of electrons. The simplest example of a 1-electron bond is found in the dihydrogen cation, H2. One-electron bonds often have about half the bond energy of a 2-electron bond, and are therefore called "half bonds". However, there are exceptions: in the case of dilithium, the bond is actually stronger for the 1-electron Li2 than for the 2-electron Li2. This exception can be explained in terms of hybridization and inner-shell effects.
The simplest example of three-electron bonding can be found in the helium dimer cation, He2. It is considered a "half bond" because it consists of only one shared electron (rather than two); in molecular orbital terms, the third electron is in an anti-bonding orbital which cancels out half of the bond formed by the other two electrons. Another example of a molecule containing a 3-electron bond, in addition to two 2-electron bonds, is nitric oxide, NO. The oxygen molecule, O2 can also be regarded as having two 3-electron bonds and one 2-electron bond, which accounts for its paramagnetism and its formal bond order of 2. Chlorine dioxide and its heavier analogues bromine dioxide and iodine dioxide also contain three-electron bonds.
Molecules with odd-electron bonds are usually highly reactive. These types of bond are only stable between atoms with similar electronegativities.
There are situations whereby a single Lewis structure is insufficient to explain the electron configuration in a molecule and its resulting experimentally-determined properties, hence a superposition of structures is needed. The same two atoms in such molecules can be bonded differently in different Lewis structures (a single bond in one, a double bond in another, or even none at all), resulting in a non-integer bond order. The nitrate ion is one such example with three equivalent structures. The bond between the nitrogen and each oxygen is a double bond in one structure and a single bond in the other two, so that the average bond order for each N–O interaction is 2 + 1 + 1/3 = 4/3.
In organic chemistry, when a molecule with a planar ring obeys Hückel's rule, where the number of π electrons fit the formula 4n + 2 (where n is an integer), it attains extra stability and symmetry. In benzene, the prototypical aromatic compound, there are 6 π bonding electrons (n = 1, 4n + 2 = 6). These occupy three delocalized π molecular orbitals (molecular orbital theory) or form conjugate π bonds in two resonance structures that linearly combine (valence bond theory), creating a regular hexagon exhibiting a greater stabilization than the hypothetical 1,3,5-cyclohexatriene.
In the case of heterocyclic aromatics and substituted benzenes, the electronegativity differences between different parts of the ring may dominate the chemical behavior of aromatic ring bonds, which otherwise are equivalent.
Certain molecules such as xenon difluoride and sulfur hexafluoride have higher co-ordination numbers than would be possible due to strictly covalent bonding according to the octet rule. This is explained by the three-center four-electron bond ("3c–4e") model which interprets the molecular wavefunction in terms of non-bonding highest occupied molecular orbitals in molecular orbital theory and resonance of sigma bonds in valence bond theory.
In three-center two-electron bonds ("3c–2e") three atoms share two electrons in bonding. This type of bonding occurs in boron hydrides such as diborane (B2H6), which are often described as electron deficient because there are not enough valence electrons to form localized (2-centre 2-electron) bonds joining all the atoms. However the more modern description using 3c–2e bonds does provide enough bonding orbitals to connect all the atoms, so that the molecules can instead be classified as electron-precise.
Each such bond (2 per molecule in diborane) contains a pair of electrons which connect the boron atoms to each other in a banana shape, with a proton (the nucleus of a hydrogen atom) in the middle of the bond, sharing electrons with both boron atoms. In certain cluster compounds, so-called four-center two-electron bonds also have been postulated.
After the development of quantum mechanics, two basic theories were proposed to provide a quantum description of chemical bonding: valence bond (VB) theory and molecular orbital (MO) theory. A more recent quantum description is given in terms of atomic contributions to the electronic density of states.
The two theories represent two ways to build up the electron configuration of the molecule. For valence bond theory, the atomic hybrid orbitals are filled with electrons first to produce a fully bonded valence configuration, followed by performing a linear combination of contributing structures (resonance) if there are several of them. In contrast, for molecular orbital theory a linear combination of atomic orbitals is performed first, followed by filling of the resulting molecular orbitals with electrons.
The two approaches are regarded as complementary, and each provides its own insights into the problem of chemical bonding. As valence bond theory builds the molecular wavefunction out of localized bonds, it is more suited for the calculation of bond energies and the understanding of reaction mechanisms. As molecular orbital theory builds the molecular wavefunction out of delocalized orbitals, it is more suited for the calculation of ionization energies and the understanding of spectral absorption bands.
At the qualitative level, both theories contain incorrect predictions. Simple (Heitler–London) valence bond theory correctly predicts the dissociation of homonuclear diatomic molecules into separate atoms, while simple (Hartree–Fock) molecular orbital theory incorrectly predicts dissociation into a mixture of atoms and ions. On the other hand, simple molecular orbital theory correctly predicts Hückel's rule of aromaticity, while simple valence bond theory incorrectly predicts that cyclobutadiene has larger resonance energy than benzene.
Although the wavefunctions generated by both theories at the qualitative level do not agree and do not match the stabilization energy by experiment, they can be corrected by configuration interaction. This is done by combining the valence bond covalent function with the functions describing all possible ionic structures or by combining the molecular orbital ground state function with the functions describing all possible excited states using unoccupied orbitals. It can then be seen that the simple molecular orbital approach overestimates the weight of the ionic structures while the simple valence bond approach neglects them. This can also be described as saying that the simple molecular orbital approach neglects electron correlation while the simple valence bond approach overestimates it.
Modern calculations in quantum chemistry usually start from (but ultimately go far beyond) a molecular orbital rather than a valence bond approach, not because of any intrinsic superiority in the former but rather because the MO approach is more readily adapted to numerical computations. Molecular orbitals are orthogonal, which significantly increases the feasibility and speed of computer calculations compared to nonorthogonal valence bond orbitals.
In COOP, COHP and BCOOP, evaluation of bond covalency is dependent on the basis set. To overcome this issue, an alternative formulation of the bond covalency can be provided in this way.
The center mass c m ( n , l , m l , m s ) {\displaystyle cm(n,l,m_{l},m_{s})} of an atomic orbital | n , l , m l , m s ⟩ , {\displaystyle |n,l,m_{l},m_{s}\rangle ,} with quantum numbers n , {\displaystyle n,} l , {\displaystyle l,} m l , {\displaystyle m_{l},} m s , {\displaystyle m_{s},} for atom A is defined as
where g | n , l , m l , m s ⟩ A ( E ) {\displaystyle g_{|n,l,m_{l},m_{s}\rangle }^{\mathrm {A} }(E)} is the contribution of the atomic orbital | n , l , m l , m s ⟩ {\displaystyle |n,l,m_{l},m_{s}\rangle } of the atom A to the total electronic density of states g ( E ) {\displaystyle g(E)} of the solid
where the outer sum runs over all atoms A of the unit cell. The energy window [ E 0 , E 1 ] {\displaystyle [E_{0},E_{1}]} is chosen in such a way that it encompasses all of the relevant bands participating in the bond. If the range to select is unclear, it can be identified in practice by examining the molecular orbitals that describe the electron density along with the considered bond.
The relative position C n A l A , n B l B {\displaystyle C_{n_{\mathrm {A} }l_{\mathrm {A} },n_{\mathrm {B} }l_{\mathrm {B} }}} of the center mass of | n A , l A ⟩ {\displaystyle |n_{\mathrm {A} },l_{\mathrm {A} }\rangle } levels of atom A with respect to the center mass of | n B , l B ⟩ {\displaystyle |n_{\mathrm {B} },l_{\mathrm {B} }\rangle } levels of atom B is given as
where the contributions of the magnetic and spin quantum numbers are summed. According to this definition, the relative position of the A levels with respect to the B levels is
where, for simplicity, we may omit the dependence from the principal quantum number n {\displaystyle n} in the notation referring to C n A l A , n B l B . {\displaystyle C_{n_{\mathrm {A} }l_{\mathrm {A} },n_{\mathrm {B} }l_{\mathrm {B} }}.}
In this formalism, the greater the value of C A , B , {\displaystyle C_{\mathrm {A,B} },} the higher the overlap of the selected atomic bands, and thus the electron density described by those orbitals gives a more covalent A−B bond. The quantity C A , B {\displaystyle C_{\mathrm {A,B} }} is denoted as the covalency of the A−B bond, which is specified in the same units of the energy E {\displaystyle E} .
An analogous effect to covalent binding is believed to occur in some nuclear systems, with the difference that the shared fermions are quarks rather than electrons. High energy proton-proton scattering cross-section indicates that quark interchange of either u or d quarks is the dominant process of the nuclear force at short distance. In particular, it dominates over the Yukawa interaction where a meson is exchanged. Therefore, covalent binding by quark interchange is expected to be the dominating mechanism of nuclear binding at small distance when the bound hadrons have covalence quarks in common. | [
{
"paragraph_id": 0,
"text": "A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding. For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full valence shell, corresponding to a stable electronic configuration. In organic chemistry, covalent bonding is much more common than ionic bonding.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Covalent bonding also includes many kinds of interactions, including σ-bonding, π-bonding, metal-to-metal bonding, agostic interactions, bent bonds, three-center two-electron bonds and three-center four-electron bonds. The term covalent bond dates from 1939. The prefix co- means jointly, associated in action, partnered to a lesser degree, etc.; thus a \"co-valent bond\", in essence, means that the atoms share \"valence\", such as is discussed in valence bond theory.",
"title": ""
},
{
"paragraph_id": 2,
"text": "In the molecule H2, the hydrogen atoms share the two electrons via covalent bonding. Covalency is greatest between atoms of similar electronegativities. Thus, covalent bonding does not necessarily require that the two atoms be of the same elements, only that they be of comparable electronegativity. Covalent bonding that entails the sharing of electrons over more than two atoms is said to be delocalized.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The term covalence in regard to bonding was first used in 1919 by Irving Langmuir in a Journal of the American Chemical Society article entitled \"The Arrangement of Electrons in Atoms and Molecules\". Langmuir wrote that \"we shall denote by the term covalence the number of pairs of electrons that a given atom shares with its neighbors.\"",
"title": "History"
},
{
"paragraph_id": 4,
"text": "The idea of covalent bonding can be traced several years before 1919 to Gilbert N. Lewis, who in 1916 described the sharing of electron pairs between atoms (and in 1926 he also coined the term \"photon\" for the smallest unit of radiant energy). He introduced the Lewis notation or electron dot notation or Lewis dot structure, in which valence electrons (those in the outer shell) are represented as dots around the atomic symbols. Pairs of electrons located between atoms represent covalent bonds. Multiple pairs represent multiple bonds, such as double bonds and triple bonds. An alternative form of representation, not shown here, has bond-forming electron pairs represented as solid lines.",
"title": "History"
},
{
"paragraph_id": 5,
"text": "Lewis proposed that an atom forms enough covalent bonds to form a full (or closed) outer electron shell. In the diagram of methane shown here, the carbon atom has a valence of four and is, therefore, surrounded by eight electrons (the octet rule), four from the carbon itself and four from the hydrogens bonded to it. Each hydrogen has a valence of one and is surrounded by two electrons (a duet rule) – its own one electron plus one from the carbon. The numbers of electrons correspond to full shells in the quantum theory of the atom; the outer shell of a carbon atom is the n = 2 shell, which can hold eight electrons, whereas the outer (and only) shell of a hydrogen atom is the n = 1 shell, which can hold only two.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "While the idea of shared electron pairs provides an effective qualitative picture of covalent bonding, quantum mechanics is needed to understand the nature of these bonds and predict the structures and properties of simple molecules. Walter Heitler and Fritz London are credited with the first successful quantum mechanical explanation of a chemical bond (molecular hydrogen) in 1927. Their work was based on the valence bond model, which assumes that a chemical bond is formed when there is good overlap between the atomic orbitals of participating atoms.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "Atomic orbitals (except for s orbitals) have specific directional properties leading to different types of covalent bonds. Sigma (σ) bonds are the strongest covalent bonds and are due to head-on overlapping of orbitals on two different atoms. A single bond is usually a σ bond. Pi (π) bonds are weaker and are due to lateral overlap between p (or d) orbitals. A double bond between two given atoms consists of one σ and one π bond, and a triple bond is one σ and two π bonds.",
"title": "Types of covalent bonds"
},
{
"paragraph_id": 8,
"text": "Covalent bonds are also affected by the electronegativity of the connected atoms which determines the chemical polarity of the bond. Two atoms with equal electronegativity will make nonpolar covalent bonds such as H–H. An unequal relationship creates a polar covalent bond such as with H−Cl. However polarity also requires geometric asymmetry, or else dipoles may cancel out, resulting in a non-polar molecule.",
"title": "Types of covalent bonds"
},
{
"paragraph_id": 9,
"text": "There are several types of structures for covalent substances, including individual molecules, molecular structures, macromolecular structures and giant covalent structures. Individual molecules have strong bonds that hold the atoms together, but generally, there are negligible forces of attraction between molecules. Such covalent substances are usually gases, for example, HCl, SO2, CO2, and CH4. In molecular structures, there are weak forces of attraction. Such covalent substances are low-boiling-temperature liquids (such as ethanol), and low-melting-temperature solids (such as iodine and solid CO2). Macromolecular structures have large numbers of atoms linked by covalent bonds in chains, including synthetic polymers such as polyethylene and nylon, and biopolymers such as proteins and starch. Network covalent structures (or giant covalent structures) contain large numbers of atoms linked in sheets (such as graphite), or 3-dimensional structures (such as diamond and quartz). These substances have high melting and boiling points, are frequently brittle, and tend to have high electrical resistivity. Elements that have high electronegativity, and the ability to form three or four electron pair bonds, often form such large macromolecular structures.",
"title": "Covalent structures"
},
{
"paragraph_id": 10,
"text": "Bonds with one or three electrons can be found in radical species, which have an odd number of electrons. The simplest example of a 1-electron bond is found in the dihydrogen cation, H2. One-electron bonds often have about half the bond energy of a 2-electron bond, and are therefore called \"half bonds\". However, there are exceptions: in the case of dilithium, the bond is actually stronger for the 1-electron Li2 than for the 2-electron Li2. This exception can be explained in terms of hybridization and inner-shell effects.",
"title": "One- and three-electron bonds"
},
{
"paragraph_id": 11,
"text": "The simplest example of three-electron bonding can be found in the helium dimer cation, He2. It is considered a \"half bond\" because it consists of only one shared electron (rather than two); in molecular orbital terms, the third electron is in an anti-bonding orbital which cancels out half of the bond formed by the other two electrons. Another example of a molecule containing a 3-electron bond, in addition to two 2-electron bonds, is nitric oxide, NO. The oxygen molecule, O2 can also be regarded as having two 3-electron bonds and one 2-electron bond, which accounts for its paramagnetism and its formal bond order of 2. Chlorine dioxide and its heavier analogues bromine dioxide and iodine dioxide also contain three-electron bonds.",
"title": "One- and three-electron bonds"
},
{
"paragraph_id": 12,
"text": "Molecules with odd-electron bonds are usually highly reactive. These types of bond are only stable between atoms with similar electronegativities.",
"title": "One- and three-electron bonds"
},
{
"paragraph_id": 13,
"text": "There are situations whereby a single Lewis structure is insufficient to explain the electron configuration in a molecule and its resulting experimentally-determined properties, hence a superposition of structures is needed. The same two atoms in such molecules can be bonded differently in different Lewis structures (a single bond in one, a double bond in another, or even none at all), resulting in a non-integer bond order. The nitrate ion is one such example with three equivalent structures. The bond between the nitrogen and each oxygen is a double bond in one structure and a single bond in the other two, so that the average bond order for each N–O interaction is 2 + 1 + 1/3 = 4/3.",
"title": "Resonance"
},
{
"paragraph_id": 14,
"text": "",
"title": "Resonance"
},
{
"paragraph_id": 15,
"text": "In organic chemistry, when a molecule with a planar ring obeys Hückel's rule, where the number of π electrons fit the formula 4n + 2 (where n is an integer), it attains extra stability and symmetry. In benzene, the prototypical aromatic compound, there are 6 π bonding electrons (n = 1, 4n + 2 = 6). These occupy three delocalized π molecular orbitals (molecular orbital theory) or form conjugate π bonds in two resonance structures that linearly combine (valence bond theory), creating a regular hexagon exhibiting a greater stabilization than the hypothetical 1,3,5-cyclohexatriene.",
"title": "Resonance"
},
{
"paragraph_id": 16,
"text": "In the case of heterocyclic aromatics and substituted benzenes, the electronegativity differences between different parts of the ring may dominate the chemical behavior of aromatic ring bonds, which otherwise are equivalent.",
"title": "Resonance"
},
{
"paragraph_id": 17,
"text": "Certain molecules such as xenon difluoride and sulfur hexafluoride have higher co-ordination numbers than would be possible due to strictly covalent bonding according to the octet rule. This is explained by the three-center four-electron bond (\"3c–4e\") model which interprets the molecular wavefunction in terms of non-bonding highest occupied molecular orbitals in molecular orbital theory and resonance of sigma bonds in valence bond theory.",
"title": "Resonance"
},
{
"paragraph_id": 18,
"text": "In three-center two-electron bonds (\"3c–2e\") three atoms share two electrons in bonding. This type of bonding occurs in boron hydrides such as diborane (B2H6), which are often described as electron deficient because there are not enough valence electrons to form localized (2-centre 2-electron) bonds joining all the atoms. However the more modern description using 3c–2e bonds does provide enough bonding orbitals to connect all the atoms, so that the molecules can instead be classified as electron-precise.",
"title": "Resonance"
},
{
"paragraph_id": 19,
"text": "Each such bond (2 per molecule in diborane) contains a pair of electrons which connect the boron atoms to each other in a banana shape, with a proton (the nucleus of a hydrogen atom) in the middle of the bond, sharing electrons with both boron atoms. In certain cluster compounds, so-called four-center two-electron bonds also have been postulated.",
"title": "Resonance"
},
{
"paragraph_id": 20,
"text": "After the development of quantum mechanics, two basic theories were proposed to provide a quantum description of chemical bonding: valence bond (VB) theory and molecular orbital (MO) theory. A more recent quantum description is given in terms of atomic contributions to the electronic density of states.",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 21,
"text": "The two theories represent two ways to build up the electron configuration of the molecule. For valence bond theory, the atomic hybrid orbitals are filled with electrons first to produce a fully bonded valence configuration, followed by performing a linear combination of contributing structures (resonance) if there are several of them. In contrast, for molecular orbital theory a linear combination of atomic orbitals is performed first, followed by filling of the resulting molecular orbitals with electrons.",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 22,
"text": "The two approaches are regarded as complementary, and each provides its own insights into the problem of chemical bonding. As valence bond theory builds the molecular wavefunction out of localized bonds, it is more suited for the calculation of bond energies and the understanding of reaction mechanisms. As molecular orbital theory builds the molecular wavefunction out of delocalized orbitals, it is more suited for the calculation of ionization energies and the understanding of spectral absorption bands.",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 23,
"text": "At the qualitative level, both theories contain incorrect predictions. Simple (Heitler–London) valence bond theory correctly predicts the dissociation of homonuclear diatomic molecules into separate atoms, while simple (Hartree–Fock) molecular orbital theory incorrectly predicts dissociation into a mixture of atoms and ions. On the other hand, simple molecular orbital theory correctly predicts Hückel's rule of aromaticity, while simple valence bond theory incorrectly predicts that cyclobutadiene has larger resonance energy than benzene.",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 24,
"text": "Although the wavefunctions generated by both theories at the qualitative level do not agree and do not match the stabilization energy by experiment, they can be corrected by configuration interaction. This is done by combining the valence bond covalent function with the functions describing all possible ionic structures or by combining the molecular orbital ground state function with the functions describing all possible excited states using unoccupied orbitals. It can then be seen that the simple molecular orbital approach overestimates the weight of the ionic structures while the simple valence bond approach neglects them. This can also be described as saying that the simple molecular orbital approach neglects electron correlation while the simple valence bond approach overestimates it.",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 25,
"text": "Modern calculations in quantum chemistry usually start from (but ultimately go far beyond) a molecular orbital rather than a valence bond approach, not because of any intrinsic superiority in the former but rather because the MO approach is more readily adapted to numerical computations. Molecular orbitals are orthogonal, which significantly increases the feasibility and speed of computer calculations compared to nonorthogonal valence bond orbitals.",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 26,
"text": "In COOP, COHP and BCOOP, evaluation of bond covalency is dependent on the basis set. To overcome this issue, an alternative formulation of the bond covalency can be provided in this way.",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 27,
"text": "The center mass c m ( n , l , m l , m s ) {\\displaystyle cm(n,l,m_{l},m_{s})} of an atomic orbital | n , l , m l , m s ⟩ , {\\displaystyle |n,l,m_{l},m_{s}\\rangle ,} with quantum numbers n , {\\displaystyle n,} l , {\\displaystyle l,} m l , {\\displaystyle m_{l},} m s , {\\displaystyle m_{s},} for atom A is defined as",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 28,
"text": "where g | n , l , m l , m s ⟩ A ( E ) {\\displaystyle g_{|n,l,m_{l},m_{s}\\rangle }^{\\mathrm {A} }(E)} is the contribution of the atomic orbital | n , l , m l , m s ⟩ {\\displaystyle |n,l,m_{l},m_{s}\\rangle } of the atom A to the total electronic density of states g ( E ) {\\displaystyle g(E)} of the solid",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 29,
"text": "where the outer sum runs over all atoms A of the unit cell. The energy window [ E 0 , E 1 ] {\\displaystyle [E_{0},E_{1}]} is chosen in such a way that it encompasses all of the relevant bands participating in the bond. If the range to select is unclear, it can be identified in practice by examining the molecular orbitals that describe the electron density along with the considered bond.",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 30,
"text": "The relative position C n A l A , n B l B {\\displaystyle C_{n_{\\mathrm {A} }l_{\\mathrm {A} },n_{\\mathrm {B} }l_{\\mathrm {B} }}} of the center mass of | n A , l A ⟩ {\\displaystyle |n_{\\mathrm {A} },l_{\\mathrm {A} }\\rangle } levels of atom A with respect to the center mass of | n B , l B ⟩ {\\displaystyle |n_{\\mathrm {B} },l_{\\mathrm {B} }\\rangle } levels of atom B is given as",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 31,
"text": "where the contributions of the magnetic and spin quantum numbers are summed. According to this definition, the relative position of the A levels with respect to the B levels is",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 32,
"text": "where, for simplicity, we may omit the dependence from the principal quantum number n {\\displaystyle n} in the notation referring to C n A l A , n B l B . {\\displaystyle C_{n_{\\mathrm {A} }l_{\\mathrm {A} },n_{\\mathrm {B} }l_{\\mathrm {B} }}.}",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 33,
"text": "In this formalism, the greater the value of C A , B , {\\displaystyle C_{\\mathrm {A,B} },} the higher the overlap of the selected atomic bands, and thus the electron density described by those orbitals gives a more covalent A−B bond. The quantity C A , B {\\displaystyle C_{\\mathrm {A,B} }} is denoted as the covalency of the A−B bond, which is specified in the same units of the energy E {\\displaystyle E} .",
"title": "Quantum mechanical description"
},
{
"paragraph_id": 34,
"text": "An analogous effect to covalent binding is believed to occur in some nuclear systems, with the difference that the shared fermions are quarks rather than electrons. High energy proton-proton scattering cross-section indicates that quark interchange of either u or d quarks is the dominant process of the nuclear force at short distance. In particular, it dominates over the Yukawa interaction where a meson is exchanged. Therefore, covalent binding by quark interchange is expected to be the dominating mechanism of nuclear binding at small distance when the bound hadrons have covalence quarks in common.",
"title": "Analogous effect in nuclear systems"
}
] | A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding. For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full valence shell, corresponding to a stable electronic configuration. In organic chemistry, covalent bonding is much more common than ionic bonding. Covalent bonding also includes many kinds of interactions, including σ-bonding, π-bonding, metal-to-metal bonding, agostic interactions, bent bonds, three-center two-electron bonds and three-center four-electron bonds. The term covalent bond dates from 1939. The prefix co- means jointly, associated in action, partnered to a lesser degree, etc.; thus a "co-valent bond", in essence, means that the atoms share "valence", such as is discussed in valence bond theory. In the molecule H2, the hydrogen atoms share the two electrons via covalent bonding. Covalency is greatest between atoms of similar electronegativities. Thus, covalent bonding does not necessarily require that the two atoms be of the same elements, only that they be of comparable electronegativity. Covalent bonding that entails the sharing of electrons over more than two atoms is said to be delocalized. | 2001-09-02T13:56:44Z | 2023-12-25T22:07:17Z | [
"Template:Chem",
"Template:Multiple image",
"Template:Sfrac",
"Template:Tmath",
"Template:Cite web",
"Template:Div col",
"Template:Cite book",
"Template:Cite journal",
"Template:Chemical bonding theory",
"Template:Authority control",
"Template:Short description",
"Template:Main article",
"Template:Chem2",
"Template:Div col end",
"Template:Reflist",
"Template:Chemical bonds",
"Template:Organic chemistry",
"Template:Redirect",
"Template:ISBN"
] | https://en.wikipedia.org/wiki/Covalent_bond |
6,247 | Condensation polymer | In polymer chemistry, condensation polymers are any kind of polymers whose process of polymerization involves a condensation reaction (i.e. a small molecule, such as water or methanol, is produced as a byproduct). Natural proteins as well as some common plastics such as nylon and PETE are formed in this way. Condensation polymers are formed by polycondensation, when the polymer is formed by condensation reactions between species of all degrees of polymerization, or by condensative chain polymerization, when the polymer is formed by sequential addition of monomers to an active site in a chain reaction. The main alternative forms of polymerization are chain polymerization and polyaddition, both of which give addition polymers.
Polycondensation A polymerization in which the growth of polymer chains proceeds by condensation reactions between molecules of all degrees of polymerization. Notes: 1. The growth steps are expressed by: Px+Py→Px+y+L {x}∈{1,2,…∞};{y}∈{1,2,…∞}
where Px and Py denote chains of degrees of polymerization x and y, respectively, and L a low-molar-mass by-product. 2. The earlier term 'polycondensation' was synonymous with 'condensation polymerization'. The current definitions of polycondensation and condensative chain polymerization were both embraced by the earlier term 'polycondensation'.
Condensation polymerization is a form of step-growth polymerization. Linear polymers are produced from bifunctional monomers, i.e. compounds with two reactive end-groups. Common condensation polymers include polyesters, polyamides such as nylon, polyacetals, and proteins.
One important class of condensation polymers are polyamides. They arise from the reaction of carboxylic acid and an amine. Examples include nylons and proteins. When prepared from amino-carboxylic acids, e.g. amino acids, the stoichiometry of the polymerization includes co-formation of water:
When prepared from diamines and dicarboxylic acids, e.g. the production of nylon 66, the polymerization produces two molecules of water per repeat unit:
Another important class of condensation polymers are polyesters. They arise from the reaction of a carboxylic acid and an alcohol. An example is polyethyleneterephthalate, the common plastic PETE (recycling #1 in the USA):
Condensation polymers tend to be more biodegradable than addition polymers. The peptide or ester bonds between monomers can be hydrolysed, especially in the presence of catalysts or bacterial enzymes. | [
{
"paragraph_id": 0,
"text": "In polymer chemistry, condensation polymers are any kind of polymers whose process of polymerization involves a condensation reaction (i.e. a small molecule, such as water or methanol, is produced as a byproduct). Natural proteins as well as some common plastics such as nylon and PETE are formed in this way. Condensation polymers are formed by polycondensation, when the polymer is formed by condensation reactions between species of all degrees of polymerization, or by condensative chain polymerization, when the polymer is formed by sequential addition of monomers to an active site in a chain reaction. The main alternative forms of polymerization are chain polymerization and polyaddition, both of which give addition polymers.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Polycondensation A polymerization in which the growth of polymer chains proceeds by condensation reactions between molecules of all degrees of polymerization. Notes: 1. The growth steps are expressed by: Px+Py→Px+y+L {x}∈{1,2,…∞};{y}∈{1,2,…∞}",
"title": ""
},
{
"paragraph_id": 2,
"text": "where Px and Py denote chains of degrees of polymerization x and y, respectively, and L a low-molar-mass by-product. 2. The earlier term 'polycondensation' was synonymous with 'condensation polymerization'. The current definitions of polycondensation and condensative chain polymerization were both embraced by the earlier term 'polycondensation'.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Condensation polymerization is a form of step-growth polymerization. Linear polymers are produced from bifunctional monomers, i.e. compounds with two reactive end-groups. Common condensation polymers include polyesters, polyamides such as nylon, polyacetals, and proteins.",
"title": ""
},
{
"paragraph_id": 4,
"text": "One important class of condensation polymers are polyamides. They arise from the reaction of carboxylic acid and an amine. Examples include nylons and proteins. When prepared from amino-carboxylic acids, e.g. amino acids, the stoichiometry of the polymerization includes co-formation of water:",
"title": "Polyamides"
},
{
"paragraph_id": 5,
"text": "When prepared from diamines and dicarboxylic acids, e.g. the production of nylon 66, the polymerization produces two molecules of water per repeat unit:",
"title": "Polyamides"
},
{
"paragraph_id": 6,
"text": "Another important class of condensation polymers are polyesters. They arise from the reaction of a carboxylic acid and an alcohol. An example is polyethyleneterephthalate, the common plastic PETE (recycling #1 in the USA):",
"title": "Polyesters"
},
{
"paragraph_id": 7,
"text": "Condensation polymers tend to be more biodegradable than addition polymers. The peptide or ester bonds between monomers can be hydrolysed, especially in the presence of catalysts or bacterial enzymes.",
"title": "Safety and environmental considerations"
}
] | In polymer chemistry, condensation polymers are any kind of polymers whose process of polymerization involves a condensation reaction. Natural proteins as well as some common plastics such as nylon and PETE are formed in this way. Condensation polymers are formed by polycondensation, when the polymer is formed by condensation reactions between species of all degrees of polymerization, or by condensative chain polymerization, when the polymer is formed by sequential addition of monomers to an active site in a chain reaction. The main alternative forms of polymerization are chain polymerization and polyaddition, both of which give addition polymers. Condensation polymerization is a form of step-growth polymerization. Linear polymers are produced from bifunctional monomers, i.e. compounds with two reactive end-groups. Common condensation polymers include polyesters, polyamides such as nylon, polyacetals, and proteins. | 2001-09-15T18:05:36Z | 2023-12-30T08:51:05Z | [
"Template:Quote box",
"Template:Reflist",
"Template:ISBN",
"Template:Cite book",
"Template:Cite encyclopedia",
"Template:Cite journal",
"Template:Authority control",
"Template:Short description",
"Template:Clear",
"Template:Commons category"
] | https://en.wikipedia.org/wiki/Condensation_polymer |
6,249 | Timeline of computing | Timeline of computing presents events in the history of computing organized by year and grouped into six topic areas: predictions and concepts, first use and inventions, hardware systems and processors, operating systems, programming languages, and new application areas.
Detailed computing timelines: before 1950, 1950–1979, 1980–1989, 1990–1999, 2000–2009, 2010–2019, 2020–present | [
{
"paragraph_id": 0,
"text": "Timeline of computing presents events in the history of computing organized by year and grouped into six topic areas: predictions and concepts, first use and inventions, hardware systems and processors, operating systems, programming languages, and new application areas.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Detailed computing timelines: before 1950, 1950–1979, 1980–1989, 1990–1999, 2000–2009, 2010–2019, 2020–present",
"title": ""
},
{
"paragraph_id": 2,
"text": "",
"title": "Graphical timeline"
}
] | Timeline of computing presents events in the history of computing organized by year and grouped into six topic areas: predictions and concepts, first use and inventions, hardware systems and processors, operating systems, programming languages, and new application areas. Detailed computing timelines: before 1950, 1950–1979, 1980–1989, 1990–1999, 2000–2009, 2010–2019, 2020–present | 2023-07-02T13:07:03Z | [
"Template:Clear",
"Template:Timeline History of Computing",
"Template:Wikibooks-inline",
"Template:Cite web",
"Template:Timelines of computing",
"Template:Short description",
"Template:History of computing"
] | https://en.wikipedia.org/wiki/Timeline_of_computing |
|
6,250 | Colorado Springs, Colorado | Colorado Springs is a home rule municipality in and the county seat of El Paso County, Colorado, United States. It is the most populous city in El Paso County, with a population of 478,961 at the 2020 census, a 15.02% increase since 2010. Colorado Springs is the second-most populous city and the most extensive city in the state of Colorado, and the 39th-most populous city in the United States. It is the principal city of the Colorado Springs metropolitan area and the second-most prominent city of the Front Range Urban Corridor. It is located in east-central Colorado on Fountain Creek, 70 miles (113 km) south of Denver.
At 6,035 feet (1,839 m) the city stands over 1 mile (1.6 km) above sea level. Colorado Springs is near the base of Pikes Peak, which rises 14,115 feet (4,302.31 m) above sea level on the eastern edge of the Southern Rocky Mountains. The city is the largest city north of Mexico above 6000 feet in elevation.
The Ute, Arapaho and Cheyenne peoples were the first recorded inhabiting the area which would become Colorado Springs. Part of the territory included in the United States' 1803 Louisiana Purchase, the current city area was designated part of the 1854 Kansas Territory. In 1859, after the first local settlement was established, it became part of the Jefferson Territory on October 24 and of El Paso County on November 28. Colorado City at the Front Range confluence of Fountain and Camp creeks was "formally organized on August 13, 1859" during the Pikes Peak Gold Rush. It served as the capital of the Colorado Territory from November 5, 1861, until August 14, 1862, when the capital was moved to Golden, before it was finally moved to Denver in 1867. So many immigrants from England had settled in Colorado Springs by the early 1870s that Colorado Springs was locally referred to as "Little London." In 1871 the Colorado Springs Company laid out the towns of La Font (later called Manitou Springs) and Fountain Colony, upstream and downstream respectively, of Colorado City. Within a year, Fountain Colony was renamed Colorado Springs and officially incorporated. The El Paso County seat shifted from Colorado City in 1873 to the Town of Colorado Springs. On December 1, 1880, Colorado Springs expanded northward with two annexations.
The second period of annexations was during 1889–90, and included Seavey's Addition, West Colorado Springs, East End, and another North End addition. In 1891 the Broadmoor Land Company built the Broadmoor suburb, which included the Broadmoor Casino, and by December 12, 1895, the city had "four Mining Exchanges and 275 mining brokers." By 1898, the city was designated into quadrants by the north-south Cascade Avenue and the east-west Washington/Pikes Peak avenues.
From 1899 to 1901 Tesla Experimental Station operated on Knob Hill, and aircraft flights to the Broadmoor's neighboring fields began in 1919. Alexander Airport north of the city opened in 1925, and in 1927 the original Colorado Springs Municipal Airport land was purchased east of the city.
The city's military presence began during World War II, beginning with Camp Carson (now the 135,000-acre Fort Carson base) that was established in 1941. During the war, the United States Army Air Forces leased land adjacent to the municipal airfield, naming it Peterson Field in December 1942.
In November 1950, Ent Air Force Base was selected as the Cold War headquarters for Air Defense Command (ADC). The former WWII Army Air Base, Peterson Field, which had been inactivated at the end of the war, was re-opened in 1951 as a U.S. Air Force base. North American Aerospace Defense Command (NORAD) was established as a hardened command and control center within the Cheyenne Mountain Complex during the Cold War.
Between 1965 and 1968, the University of Colorado Colorado Springs, Pikes Peak State College and Colorado Technical University were established in or near the city. In 1977 most of the former Ent AFB became a US Olympic training center. The Libertarian Party was founded within the city in the 1970s.
On October 1, 1981, the Broadmoor Addition, Cheyenne Canon, Ivywild, Skyway, and Stratton Meadows were annexed after the Colorado Supreme Court "overturned a district court decision that voided the annexation". Further annexations expanding the city include the Nielson Addition and Vineyard Commerce Park Annexation in September 2008.
The city lies in a semi-arid Steppe climate region with the Southern Rocky Mountains to the west, the Palmer Divide to the north, high plains further east, and high desert lands to the south when leaving Fountain and approaching Pueblo. Colorado Springs is 69 miles (111 km) or one hour and five minutes south of Denver by car using I-25.
Colorado Springs has the greatest total area of any municipality in Colorado. At the 2020 United States Census, the city had a total area of 195.761 square miles (507.019 km) including 0.362 square miles (0.937 km) of water.
Colorado Springs has many features of a modern urban area such as parks, bike trails, and open spaces. However, it is not exempt from problems that typically plague cities experiencing tremendous growth such as overcrowded roads and highways, crime, sprawl, and government budgetary issues. Many of the problems are indirectly or directly caused by the city's difficulty in coping with the large population growth experienced since 1997, and the annexation of the Banning Lewis Ranch area to accommodate further population growth of 175,000 future residents.
Colorado Springs has a cooler, dry-winter semi-arid climate (Köppen BSk), and its location just east of the Rocky Mountains affords it the rapid warming influence from chinook winds during winter but also subjects it to drastic day-to-day variability in weather conditions. The city has abundant sunshine year-round, averaging 243 sunny days per year, and receives approximately 16.5 inches (419 mm) of annual precipitation. Due to unusually low precipitation for several years after flooding in 1999, Colorado Springs enacted lawn water restrictions in 2002. These were lifted in 2005 but permanently reinstated in December 2019.
Colorado Springs is one of the most active lightning strike areas in the United States. This natural phenomenon led Nikola Tesla to select Colorado Springs as the preferred location to build his lab and study electricity.
December is typically the coldest month, averaging 30.8 °F (−0.7 °C). Historically, January had been the coldest month, but, in recent years, December has had both lower daily maxima and minima. Typically, there are 5.2 nights with sub-0 °F (−18 °C) lows and 23.6 days where the high does not rise above freezing.
Snowfall is usually moderate and remains on the ground briefly because of direct sun, with the city receives 38 inches (97 cm) per season, although the mountains to the west often receive in excess of triple that amount; March is the snowiest month in the region, both by total accumulation and number of days with measurable snowfall. In addition, 8 of the top 10 heaviest 24-hour snowfalls have occurred from March to May. Summers are warm, with July, the warmest month, averaging 70.9 °F (21.6 °C), and 18 days of 90 °F (32 °C)+ highs annually. Due to the high elevation and aridity, nights are usually relatively cool and rarely does the low remain above 70 °F (21 °C). Dry weather generally prevails, but brief afternoon thunderstorms are common, especially in July and August when the city receives the majority of its annual rainfall, due to the North American monsoon.
The first autumn freeze and the last freeze in the spring, on average, occur on October 2 and May 6, respectively; the average window for measurable snowfall (≥0.1 in or 0.25 cm) is October 21 through April 25. Extreme temperatures range from 101 °F (38 °C) on June 26, 2012 and most recently on June 21, 2016, down to −27 °F (−33 °C) on February 1, 1951, and December 9, 1919.
As of the 2020 United States Census, the population of the City of Colorado Springs was 478,961 (40th most populous U.S. city), the population of the Colorado Springs Metropolitan Statistical Area was 755,105 (79th most populous MSA), and the population of the Front Range Urban Corridor was 5,055,344.
As of the April 2010 census, 78.8% of the population of the city was White (non-Hispanic Whites were 70.7% of the population, compared with 86.6% in 1970), 16.1% Hispanic or Latino of any race (compared with 7.4% in 1970), 6.3% Black or African American, 3.0% Asian, 1.0% descended from indigenous peoples of the Americas, 0.3% descended from indigenous Hawaiians and other Pacific islanders, 5.5% of some other race, and 5.1% of two or more races. Mexican Americans made up 14.6% of the city's population, compared with 9.1% in 1990. The median age in the city was 35 years.
Colorado Springs's economy is driven primarily by the military, the high-tech industry, and tourism, in that order. The city is experiencing growth in the service sectors. In June 2019, before the COVID-19 pandemic, the unemployment rate was 3.3%. The state's unemployment rate in June 2022 was 3.4% compared to 3.6% for the nation.
As of 2021, there are nearly 45,000 active-duty troops in Colorado Springs. There are more than 100,000 veterans and thousands of reservists. The military and defense contractors supply more than 40% of the Pikes Peak region's economy.
Colorado Springs is home to the Peterson Space Force Base, Schriever Space Force Base, Cheyenne Mountain Space Force Station, U.S. Space Command, and Space Operations Command— the largest contingent of space service military installations. They are responsible for intelligence gathering, space operations, and cyber missions.
Peterson Space Force Base is responsible for the North American Aerospace Defense Command (NORAD) and the United States Northern Command (USNORTHCOM) headquarters, Space Operations Command, and Space Deltas 2, 3, and 7. Located at Peterson is the 302nd Airlift Wing, an Air Force Reserve unit, that transports passengers and cargo and fights wildfires.
Schriever Space Force Base is responsible for Joint Task Force-Space Defense and Space Deltas 6, 8, and 9. The NORAD and USNORTHCOM Alternate Command Center is located at the Cheyenne Mountain Complex. Within the mountain complex, the Cheyenne Mountain Space Force Station has been operated by Space Operations Command. On January 13, 2021, the Air Force announced a new permanent home for Space Command, moving it from Colorado Springs to Huntsville, Alabama in 2026, but the decision could be reversed by Congress.
Army divisions are trained and stationed at Fort Carson. The United States Air Force Academy was established after World War II, on land donated by the City of Colorado Springs.
The defense industry forms a significant part of the Colorado Springs economy, with some of the city's largest employers being defense contractors. Some defense corporations have left or downsized city campuses, but slight growth has been recorded. Significant defense corporations in the city include Northrop Grumman, Boeing, General Dynamics, L3Harris Technologies, SAIC, ITT, Lockheed Martin, and Bluestaq. The Space Foundation is based in Colorado Springs.
A large percentage of Colorado Springs's economy is still based on manufacturing high-tech and complex electronic equipment. The high-tech sector in the Colorado Springs area has decreased its overall presence from 2000 to 2006 (from around 21,000 to around 8,000), with notable reductions in information technology and complex electronic equipment. Current trends project the high-tech employment ratio will continue to decrease.
High-tech corporations offering fibre-optics to the premises connections within the city include: Lumen Technologies, Comcast and other providers as of 2023. Hewlett-Packard still has some sales, support, and SAN storage engineering center for the computer industry. Storage Networking Industry Association is the home of the SNIA Technology Center. Keysight Technologies, spun off in 2014 from Agilent, which was itself spun off from HP in 1999 as an independent, publicly traded company, has its oscilloscope research and development division based in Colorado Springs. Intel had 250 employees in 2009. The Intel facility is now used for the centralized unemployment offices, social services, El Paso county offices, and a bitcoin mining facility. Microchip Technology (formerly Atmel), is a chip fabrication organization. The Apple Inc. facility was sold to Sanmina-SCI in 1996.
Almost immediately following the arrival of railroads beginning in 1871, the city's location at the base of Pikes Peak and the Rocky Mountains made it a popular tourism destination. Tourism is the third largest employer in the Pikes Peak region, accounting for more than 16,000 jobs. In 2018, 23 million day and overnight visitors came to the area, contributing $2.4 billion in revenue.
Colorado Springs has more than 55 attractions and activities in the area, including Garden of the Gods park, United States Air Force Academy, the ANA Money Museum, Cheyenne Mountain Zoo, Colorado Springs Fine Arts Center at Colorado College, Old Colorado City, The National Museum of World War II Aviation, and the U.S. Olympic & Paralympic Training Center. In 2020, the U.S. Olympic & Paralympic Museum opened; the Flying W Ranch Chuckwagon Dinner & Western Show reopened in 2020. A new Pikes Peak Summit Complex opened at the 14,115-foot summit in 2021. The Manitou and Pikes Peak Railway also reopened in 2021.
The downtown Colorado Springs Visitor Information Center offers free area information to leisure and business travelers. The Cultural Office of the Pikes Peak Region (COPPeR), also downtown, supports and advocates for the arts throughout the Pikes Peak Region. It operates the PeakRadar website to communicate city events.
Colorado Springs is home to the annual Colorado Springs Labor Day Lift Off, a hot air balloon festival that takes place over Labor Day weekend at the city's Memorial Park.
Other annual events include: a comic book convention and science fiction convention called GalaxyFest in February, a pride parade called PrideFest in July, the Greek Festival, the Pikes Peak Ascent and Marathon, and the Steers & Beers Whiskey and Beer Festival in August, and the Emma Crawford Coffin Races and Festival in nearby Manitou Springs and Arts Month in October.
The Colorado Springs Festival of Lights Parade is held the first Saturday in December. The parade is held on Tejon Street in Downtown Colorado Springs.
In 2017, Colorado had the third-most craft breweries at 348. Breweries and microbreweries have become popular in Colorado Springs, which hosts over 30 of them.
Although houses of worship of almost every major world religion are within the city, Colorado Springs has in particular attracted a large influx of Evangelical Christians and Christian organizations in recent years. At one time Colorado Springs was the national headquarters for 81 different religious organizations, earning the city the tongue-in-cheek nicknames "the Evangelical Vatican" and "The Christian Mecca."
Religious groups with regional or international headquarters in Colorado Springs include:
Although Colorado voters approved Colorado Amendment 64, a constitutional amendment in 2012 legalizing retail sales of marijuana for recreational purposes, the Colorado Springs city council voted not to permit retail shops in the city, as was allowed in the amendment. Medical marijuana outlets continue to operate in Colorado Springs. In 2015, there were 91 medical marijuana clinics in the city, which reported sales of $59.6 million in 2014, up 11 percent from the previous year but without recreational marijuana shops. On April 26, 2016, Colorado Springs city council decided to extend the current six-month moratorium to eighteen months with no new licenses to be granted until May 2017. A scholarly paper suggested the city would give up $25.4 million in tax revenue and fees if the city continued to thwart the industry from opening within the city limits. As of March 1, 2018, there were 131 medical marijuana centers and no recreational cannabis stores. As of 2019 Colorado Springs is still one of seven towns that have only allowed for medical marijuana.
Colorado Springs has been the subject of or setting for many books, films and television shows, and is a frequent backdrop for political thrillers and military-themed stories because of its many military installations and vital importance to the United States' continental defense. Notable television series using the city as a setting include Dr. Quinn, Medicine Woman, Homicide Hunter and the Stargate series Stargate SG-1, as well as the films WarGames, The Prestige, and BlacKkKlansman.
In a North Korean propaganda video released in April 2013, Colorado Springs was inexplicably singled out as one of four targets for a missile strike. The video failed to pinpoint Colorado Springs on the map, instead showing a spot somewhere in Louisiana.
Colorado Springs, dubbed Olympic City USA, is home to the United States Olympic & Paralympic Training Center and the headquarters of the United States Olympic & Paralympic Committee and the United States Anti-Doping Agency.
Further, over 50 national sports organizations (non-Olympic) headquarter in Colorado Springs. These include the National Strength and Conditioning Association, Sports Incubator, a various non-Olympic Sports (such as USA Ultimate), and more.
Colorado Springs and Denver hosted the 1962 World Ice Hockey Championships.
The city has a long association with the sport of figure skating, having hosted the U.S. Figure Skating Championships six times and the World Figure Skating Championships five times. It is home to the World Figure Skating Museum and Hall of Fame and the Broadmoor Skating Club, a notable training center for the sport. In recent years, the Broadmoor World Arena has hosted skating events such as Skate America and the Four Continents Figure Skating Championships.
Colorado Springs is home to 2 two professional baseball teams, The Rocky Mountain Vibes who are a member of the Pioneer League and are not affiliated with any MLB teams as of 2023, The Colorado Springs Snow Sox professional baseball team is based in Colorado Springs. The team is a member of the Pecos League, an independent baseball league which is not affiliated with Major or Minor League Baseball.
The Pikes Peak International Hill Climb (PPIHC), also known as The Race to the Clouds, is an annual invitational automobile and motorcycle hill climb to the summit of Pikes Peak, every year on the last Sunday of June. The highway wasn't completely paved until 2011.
The local colleges feature many sports teams. Notable among them are several nationally competitive NCAA Division I teams: United States Air Force Academy (Falcons) Football, Basketball and Hockey and Colorado College (Tigers) Hockey, and Women's Soccer.
Colorado Springs was the original headquarters of the Professional Bull Riders (PBR) from its founding in 1992 until 2005, when the organization was moved to Pueblo.
The city's Parks, Recreation and Cultural Services manage 136 neighborhood parks, eight community parks, seven regional parks, and five sports complexes, totaling 9,000 acres (3,600 ha). They also manage 500 acres (200 ha) of trails, of which 160 miles (260 km) are park trails and 105 miles (169 km) are urban. There are 5,000 acres (2,000 ha) of open space in 48 open-space areas.
Garden of the Gods is on Colorado Springs's western edge. It is a National Natural Landmark, with 300 foot (91 m) red/orange sandstone rock formations often viewed against a backdrop of the snow-capped Pikes Peak. This park is free to the public and offers many recreational opportunities, such as hiking, rock climbing, cycling, horseback riding and tours. It offers a variety of annual events, one of the most popular of which is the Starlight Spectacular, a recreational bike ride held every summer to benefit the Trails and Open Space Coalition of Colorado Springs.
Colorado Springs has several major city parks, such as Palmer Park, America the Beautiful Park in downtown, Memorial Park, which includes many sports fields, an indoor swimming pool and skating rink, a skateboard bowl and two half-pipes, and Monument Valley Park, which has walking and biking paths, an outdoor swimming pool and pickleball courts. Monument Valley Park also has Tahama Spring, the original spring in Colorado Springs. Austin Bluffs Park affords a place of recreation in eastern Colorado Springs. El Paso County Regional Parks include Bear Creek Regional Park, Bear Creek Dog Park, Fox Run Regional Park and Fountain Creek Regional Park and Nature Center. Ponderosa pine (Pinus ponderosa), Gambel oak (Quercus gambelii), narrowleaf yucca (Yucca angustissima, syn. Yucca glauca) and prickly pear cactus (Opuntia macrorhiza).
Three trails, the New Santa Fe Regional Trail, Pikes Peak Greenway and Fountain Creek Regional Trail, form a continuous path from Palmer Lake, through Colorado Springs, to Fountain, Colorado. The majority of the trail between Palmer Lake and Fountain is a soft surface breeze gravel trail. A major segment of the trail within the Colorado Springs city limits is paved. The trails, except Monument Valley Park trails, may be used for equestrian traffic. Motorized vehicles are not allowed on the trails. Many of the trails are interconnected, having main spine trails, like the Pikes Peak Greenway, that lead to secondary trails.
On November 2, 2010, Colorado Springs voters adopted a council-strong mayor form of government. The City of Colorado Springs transitioned to the new system of government in 2011. Under the council-strong mayor system of government, the mayor is the chief executive and the city council is the legislative branch. The mayor is a full-time elected position and not a member of the council. The council has nine members, six of whom represent one of six equally populated districts each. The remaining three members are elected at-large.
Colorado Springs City Hall was built from 1902 to 1904 on land donated by W. S. Stratton.
The Colorado Springs City Council consists of nine elected officials, six of whom represent districts and three of whom represent the city at-large.
In 2017 Caleb Hannan wrote in Politico that Colorado Springs was "staunchly Republican", "a right-wing counterweight to liberal Boulder", and that a study ranked it "the fourth most conservative city in America". In 2016 Hannan wrote that downtown Colorado Springs had a different political vibe from the overall area's and that there were "superficial signs of changing demographics". Since 2020, Colorado Springs has continued to shift towards the political center. In 2022, Governor Jared Polis won the city in his bid for reelection. In the 2023 mayoral election, independent candidate Yemi Mobolade handily won the race and became the first elected non-Republican mayor of the city.
In addition the state of Colorado runs the Colorado School for the Deaf and Blind, a residential school for people up to age 21 and established in 1874, in the city.
State institutions offering bachelors and graduate degree programs in Colorado Springs include University of Colorado Colorado Springs (UCCS) with more than 12,000 students, and, Pikes Peak State College which offers mostly two-year degree associate degrees. The United States Air Force Academy is a federal institution offering bachelor's degrees for officer candidates.
Private non-profit institutions include Colorado College established in 1874 with about 2,000 undergraduates. Colorado Christian University has its Colorado Springs Center in the city.
Private for-profit institutions include Colorado Technical University whose main campus is in Colorado Springs and IntelliTec College a technical training school.
Colorado Springs is primarily served by one interstate highway. I-25 runs north and south through Colorado, and traverses the city for nearly 18 miles (29 km), entering the city south of Circle Drive and exiting north of North Gate Boulevard. In El Paso County it is known as Ronald Reagan Highway.
A number of state and U.S. highways serve the city. State Highway 21 is a major east side semi-expressway from Black Forest to Fountain, known locally and co-signed as Powers Boulevard. State Highway 83 runs north–south from central Denver to northern Colorado Springs. State Highway 94 runs east–west from western Cheyenne County to eastern Colorado Springs where it terminates at US 24. US 24 is a major route through the city and county, providing access to Woodland Park via Ute Pass to the west and downtown, Nob Hill and numerous suburbs to the east. It is co-signed with Platte Ave after SH 21 and originally carried local traffic through town. The Martin Luther King Jr Bypass runs from I-25 near Circle Drive along Fountain Blvd to SH 21, then east again. State Highway 115 begins in Cañon City, traveling north along the western edge of Fort Carson; when it reaches the city limits it merges with Nevada Avenue, a signed Business Route of US 85. US 85 and SH 115 are concurrent between Lake Avenue and I-25. US 85 enters the city at Fountain and was signed at Venetucci Blvd, Lake Avenue, and Nevada Avenue at various points in history; however most of US 85 is concurrent with I-25 and is not signed.
In November 2015, voters in Colorado Springs overwhelmingly passed ballot measure 2C, dedicating funds from a temporary sales tax increase to much needed road and infrastructure improvements over five years. This temporary increase is estimated to bring in approximately $50 million annually, which will be used solely to improve roads and infrastructure. The ballot measure passed by a margin of approximately 65–35%.
In 2004, the voters of Colorado Springs and El Paso County established the Pikes Peak Rural Transportation Authority.
In early 2010, the city of Colorado Springs approved an expansion of the northernmost part of Powers Boulevard in order to create an Interstate 25 bypass commonly referred to as the Copper Ridge Expansion.
Colorado Springs Airport (COS; ICAO: KCOS) has been in operation since 1925. It is the second-largest commercial airport in the state, after Denver International Airport (DEN; ICAO: KDEN). It covers 7,200 acres (2,900 ha) of land at an elevation of approximately 6,200 feet (1,900 m). COS is considered to be a joint-use civilian and military airport, as Peterson Space Force Base is a tenant of the airport. It has three paved runways: 17L/35R is 13,501 by 150 feet (4,115 by 46 m), the runway 17R/35L is 11,022 by 150 feet (3,360 by 46 m) and the runway 13/31 is 8,270 by 150 feet (2,521 by 46 m). The airport handled 2,134,618 passengers in 2022, and is served by American, Avelo, Delta, Southwest, Sun Country, and United.
Freight service is provided by Union Pacific and BNSF.
Once an important hub, the city was once served by four Class 1 railroads, as well as a number of smaller operators, some of which were narrow gauge, and an extensive streetcar system, the Colorado Springs and Interurban Railway .
Currently there is no intercity passenger service; the last remaining services connecting the Front Range cities ceased with the formation of Amtrak in 1971 . Front Range Passenger Rail is a current proposal (as of 2023) to link the cities from Pueblo in the south, north to Fort Collins and possibly Cheyenne, Wyoming.
In April 2018, the Colorado Springs City Council approved a Bike Master Plan. The vision of the city's Bike Master Plan is "a healthy and vibrant Colorado Springs where bicycling is one of many transportation options for a large portion of the population, and where a well-connected and well-maintained network of urban trails, single-track, and on-street infrastructure offers a bicycling experience for present and future generations that is safe, convenient, and fun for getting around, getting in shape, or getting away." Bike lanes in Colorado Springs have not been deployed without controversy. According to The Gazette, their readers "have mixed feelings for new bike lanes." In December 2016, the City removed a bike lane along Research Parkway due to overwhelming opposition; an online survey found that 80.5% of respondents opposed the bike lane. The Gazette has stated that since the Bike Master Plan was adopted by city council, "no issue has elicited more argument in The Gazette pages," and due to this immense public interest, on February 25, 2019, The Gazette hosted a town hall meeting called "Battle of the Bike Lanes."
A 2011 study by Walk Score ranked Colorado Springs 34th most walkable of fifty largest U.S. cities.
Mountain Metropolitan Transit (MMT) is testing Battery Electric Buses (BEB), and if the buses perform well, the agency plans to acquire its first three BEBs in 2021 using funds from the Volkswagen emissions scandal and resulting lawsuit and settlement. On April 22, 2022, Mountain Metro unveiled four new all-electric Proterra ZX5 buses to be added to their fleet. The new buses join their current fleet of 67 clean diesel buses. They are funded by the Colorado Department of Transportation Division of Transit and Rail Settlement Transit Bus Replacement Program, Volkswagen Diesel Emission Settlement trust, and Federal transit Administration 5339(b) Buses and Bus Facilities Program grant. The Proterra ZX5 buses run 220 to 330 miles on a single charge, and cost $1.2 million per bus.
Mountain Metro Mobility is an Americans with Disabilities Act (ADA) federally mandated complementary ADA paratransit service, which provides demand-response service for individuals with mobility needs that prevent them from using the fixed-route bus system.
Mountain Metro Rides offers alternative transportation options to residents of the Pikes Peak Region. The program is designed to reduce congestion and pollution by encouraging people to commute by carpool, vanpool, bicycling or walking.
Bustang provides intercity transportation to Colorado Springs. It is part of the South and Outrider lines, which connect to Denver and to Lamar. There is an additional line that connects Colorado Springs directly to the Denver Tech Center.
See also National Register of Historic Places in Colorado Springs, Colorado
Colorado Springs' sister cities are:
Colorado Springs's sister city organization began when it became partners with Fujiyoshida. The torii gate erected to commemorate the relationship stands at the corner of Bijou Street and Nevada Avenue, and is one of the city's most recognizable landmarks. The torii gate, crisscrossed bridge and shrine, in the median between Platte and Bijou Streets downtown, were a gift to Colorado Springs, erected in 1966 by the Rotary Club of Colorado Springs to celebrate the friendship between the two communities. A plaque near the torii gate states that "the purpose of the sister city relationship is to promote understanding between the people of our two countries and cities". The Fujiyoshida Student exchange program has become an annual event.
In 2006 and 2010, the Bankstown TAP (Talent Advancement Program) performed with the Youth Symphony and the Colorado Springs Children's Chorale as part of the annual "In Harmony" program. A notable similarity between Colorado Springs and its sister cities is their geographic positions: three of the seven cities are near the foot of a major mountain or mountain range, as is Colorado Springs. | [
{
"paragraph_id": 0,
"text": "Colorado Springs is a home rule municipality in and the county seat of El Paso County, Colorado, United States. It is the most populous city in El Paso County, with a population of 478,961 at the 2020 census, a 15.02% increase since 2010. Colorado Springs is the second-most populous city and the most extensive city in the state of Colorado, and the 39th-most populous city in the United States. It is the principal city of the Colorado Springs metropolitan area and the second-most prominent city of the Front Range Urban Corridor. It is located in east-central Colorado on Fountain Creek, 70 miles (113 km) south of Denver.",
"title": ""
},
{
"paragraph_id": 1,
"text": "At 6,035 feet (1,839 m) the city stands over 1 mile (1.6 km) above sea level. Colorado Springs is near the base of Pikes Peak, which rises 14,115 feet (4,302.31 m) above sea level on the eastern edge of the Southern Rocky Mountains. The city is the largest city north of Mexico above 6000 feet in elevation.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The Ute, Arapaho and Cheyenne peoples were the first recorded inhabiting the area which would become Colorado Springs. Part of the territory included in the United States' 1803 Louisiana Purchase, the current city area was designated part of the 1854 Kansas Territory. In 1859, after the first local settlement was established, it became part of the Jefferson Territory on October 24 and of El Paso County on November 28. Colorado City at the Front Range confluence of Fountain and Camp creeks was \"formally organized on August 13, 1859\" during the Pikes Peak Gold Rush. It served as the capital of the Colorado Territory from November 5, 1861, until August 14, 1862, when the capital was moved to Golden, before it was finally moved to Denver in 1867. So many immigrants from England had settled in Colorado Springs by the early 1870s that Colorado Springs was locally referred to as \"Little London.\" In 1871 the Colorado Springs Company laid out the towns of La Font (later called Manitou Springs) and Fountain Colony, upstream and downstream respectively, of Colorado City. Within a year, Fountain Colony was renamed Colorado Springs and officially incorporated. The El Paso County seat shifted from Colorado City in 1873 to the Town of Colorado Springs. On December 1, 1880, Colorado Springs expanded northward with two annexations.",
"title": "History"
},
{
"paragraph_id": 3,
"text": "The second period of annexations was during 1889–90, and included Seavey's Addition, West Colorado Springs, East End, and another North End addition. In 1891 the Broadmoor Land Company built the Broadmoor suburb, which included the Broadmoor Casino, and by December 12, 1895, the city had \"four Mining Exchanges and 275 mining brokers.\" By 1898, the city was designated into quadrants by the north-south Cascade Avenue and the east-west Washington/Pikes Peak avenues.",
"title": "History"
},
{
"paragraph_id": 4,
"text": "From 1899 to 1901 Tesla Experimental Station operated on Knob Hill, and aircraft flights to the Broadmoor's neighboring fields began in 1919. Alexander Airport north of the city opened in 1925, and in 1927 the original Colorado Springs Municipal Airport land was purchased east of the city.",
"title": "History"
},
{
"paragraph_id": 5,
"text": "The city's military presence began during World War II, beginning with Camp Carson (now the 135,000-acre Fort Carson base) that was established in 1941. During the war, the United States Army Air Forces leased land adjacent to the municipal airfield, naming it Peterson Field in December 1942.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "In November 1950, Ent Air Force Base was selected as the Cold War headquarters for Air Defense Command (ADC). The former WWII Army Air Base, Peterson Field, which had been inactivated at the end of the war, was re-opened in 1951 as a U.S. Air Force base. North American Aerospace Defense Command (NORAD) was established as a hardened command and control center within the Cheyenne Mountain Complex during the Cold War.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "Between 1965 and 1968, the University of Colorado Colorado Springs, Pikes Peak State College and Colorado Technical University were established in or near the city. In 1977 most of the former Ent AFB became a US Olympic training center. The Libertarian Party was founded within the city in the 1970s.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "On October 1, 1981, the Broadmoor Addition, Cheyenne Canon, Ivywild, Skyway, and Stratton Meadows were annexed after the Colorado Supreme Court \"overturned a district court decision that voided the annexation\". Further annexations expanding the city include the Nielson Addition and Vineyard Commerce Park Annexation in September 2008.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "The city lies in a semi-arid Steppe climate region with the Southern Rocky Mountains to the west, the Palmer Divide to the north, high plains further east, and high desert lands to the south when leaving Fountain and approaching Pueblo. Colorado Springs is 69 miles (111 km) or one hour and five minutes south of Denver by car using I-25.",
"title": "Geography"
},
{
"paragraph_id": 10,
"text": "Colorado Springs has the greatest total area of any municipality in Colorado. At the 2020 United States Census, the city had a total area of 195.761 square miles (507.019 km) including 0.362 square miles (0.937 km) of water.",
"title": "Geography"
},
{
"paragraph_id": 11,
"text": "Colorado Springs has many features of a modern urban area such as parks, bike trails, and open spaces. However, it is not exempt from problems that typically plague cities experiencing tremendous growth such as overcrowded roads and highways, crime, sprawl, and government budgetary issues. Many of the problems are indirectly or directly caused by the city's difficulty in coping with the large population growth experienced since 1997, and the annexation of the Banning Lewis Ranch area to accommodate further population growth of 175,000 future residents.",
"title": "Geography"
},
{
"paragraph_id": 12,
"text": "Colorado Springs has a cooler, dry-winter semi-arid climate (Köppen BSk), and its location just east of the Rocky Mountains affords it the rapid warming influence from chinook winds during winter but also subjects it to drastic day-to-day variability in weather conditions. The city has abundant sunshine year-round, averaging 243 sunny days per year, and receives approximately 16.5 inches (419 mm) of annual precipitation. Due to unusually low precipitation for several years after flooding in 1999, Colorado Springs enacted lawn water restrictions in 2002. These were lifted in 2005 but permanently reinstated in December 2019.",
"title": "Geography"
},
{
"paragraph_id": 13,
"text": "Colorado Springs is one of the most active lightning strike areas in the United States. This natural phenomenon led Nikola Tesla to select Colorado Springs as the preferred location to build his lab and study electricity.",
"title": "Geography"
},
{
"paragraph_id": 14,
"text": "December is typically the coldest month, averaging 30.8 °F (−0.7 °C). Historically, January had been the coldest month, but, in recent years, December has had both lower daily maxima and minima. Typically, there are 5.2 nights with sub-0 °F (−18 °C) lows and 23.6 days where the high does not rise above freezing.",
"title": "Geography"
},
{
"paragraph_id": 15,
"text": "Snowfall is usually moderate and remains on the ground briefly because of direct sun, with the city receives 38 inches (97 cm) per season, although the mountains to the west often receive in excess of triple that amount; March is the snowiest month in the region, both by total accumulation and number of days with measurable snowfall. In addition, 8 of the top 10 heaviest 24-hour snowfalls have occurred from March to May. Summers are warm, with July, the warmest month, averaging 70.9 °F (21.6 °C), and 18 days of 90 °F (32 °C)+ highs annually. Due to the high elevation and aridity, nights are usually relatively cool and rarely does the low remain above 70 °F (21 °C). Dry weather generally prevails, but brief afternoon thunderstorms are common, especially in July and August when the city receives the majority of its annual rainfall, due to the North American monsoon.",
"title": "Geography"
},
{
"paragraph_id": 16,
"text": "The first autumn freeze and the last freeze in the spring, on average, occur on October 2 and May 6, respectively; the average window for measurable snowfall (≥0.1 in or 0.25 cm) is October 21 through April 25. Extreme temperatures range from 101 °F (38 °C) on June 26, 2012 and most recently on June 21, 2016, down to −27 °F (−33 °C) on February 1, 1951, and December 9, 1919.",
"title": "Geography"
},
{
"paragraph_id": 17,
"text": "As of the 2020 United States Census, the population of the City of Colorado Springs was 478,961 (40th most populous U.S. city), the population of the Colorado Springs Metropolitan Statistical Area was 755,105 (79th most populous MSA), and the population of the Front Range Urban Corridor was 5,055,344.",
"title": "Demographics"
},
{
"paragraph_id": 18,
"text": "As of the April 2010 census, 78.8% of the population of the city was White (non-Hispanic Whites were 70.7% of the population, compared with 86.6% in 1970), 16.1% Hispanic or Latino of any race (compared with 7.4% in 1970), 6.3% Black or African American, 3.0% Asian, 1.0% descended from indigenous peoples of the Americas, 0.3% descended from indigenous Hawaiians and other Pacific islanders, 5.5% of some other race, and 5.1% of two or more races. Mexican Americans made up 14.6% of the city's population, compared with 9.1% in 1990. The median age in the city was 35 years.",
"title": "Demographics"
},
{
"paragraph_id": 19,
"text": "Colorado Springs's economy is driven primarily by the military, the high-tech industry, and tourism, in that order. The city is experiencing growth in the service sectors. In June 2019, before the COVID-19 pandemic, the unemployment rate was 3.3%. The state's unemployment rate in June 2022 was 3.4% compared to 3.6% for the nation.",
"title": "Economy"
},
{
"paragraph_id": 20,
"text": "As of 2021, there are nearly 45,000 active-duty troops in Colorado Springs. There are more than 100,000 veterans and thousands of reservists. The military and defense contractors supply more than 40% of the Pikes Peak region's economy.",
"title": "Economy"
},
{
"paragraph_id": 21,
"text": "Colorado Springs is home to the Peterson Space Force Base, Schriever Space Force Base, Cheyenne Mountain Space Force Station, U.S. Space Command, and Space Operations Command— the largest contingent of space service military installations. They are responsible for intelligence gathering, space operations, and cyber missions.",
"title": "Economy"
},
{
"paragraph_id": 22,
"text": "Peterson Space Force Base is responsible for the North American Aerospace Defense Command (NORAD) and the United States Northern Command (USNORTHCOM) headquarters, Space Operations Command, and Space Deltas 2, 3, and 7. Located at Peterson is the 302nd Airlift Wing, an Air Force Reserve unit, that transports passengers and cargo and fights wildfires.",
"title": "Economy"
},
{
"paragraph_id": 23,
"text": "Schriever Space Force Base is responsible for Joint Task Force-Space Defense and Space Deltas 6, 8, and 9. The NORAD and USNORTHCOM Alternate Command Center is located at the Cheyenne Mountain Complex. Within the mountain complex, the Cheyenne Mountain Space Force Station has been operated by Space Operations Command. On January 13, 2021, the Air Force announced a new permanent home for Space Command, moving it from Colorado Springs to Huntsville, Alabama in 2026, but the decision could be reversed by Congress.",
"title": "Economy"
},
{
"paragraph_id": 24,
"text": "Army divisions are trained and stationed at Fort Carson. The United States Air Force Academy was established after World War II, on land donated by the City of Colorado Springs.",
"title": "Economy"
},
{
"paragraph_id": 25,
"text": "The defense industry forms a significant part of the Colorado Springs economy, with some of the city's largest employers being defense contractors. Some defense corporations have left or downsized city campuses, but slight growth has been recorded. Significant defense corporations in the city include Northrop Grumman, Boeing, General Dynamics, L3Harris Technologies, SAIC, ITT, Lockheed Martin, and Bluestaq. The Space Foundation is based in Colorado Springs.",
"title": "Economy"
},
{
"paragraph_id": 26,
"text": "A large percentage of Colorado Springs's economy is still based on manufacturing high-tech and complex electronic equipment. The high-tech sector in the Colorado Springs area has decreased its overall presence from 2000 to 2006 (from around 21,000 to around 8,000), with notable reductions in information technology and complex electronic equipment. Current trends project the high-tech employment ratio will continue to decrease.",
"title": "Economy"
},
{
"paragraph_id": 27,
"text": "High-tech corporations offering fibre-optics to the premises connections within the city include: Lumen Technologies, Comcast and other providers as of 2023. Hewlett-Packard still has some sales, support, and SAN storage engineering center for the computer industry. Storage Networking Industry Association is the home of the SNIA Technology Center. Keysight Technologies, spun off in 2014 from Agilent, which was itself spun off from HP in 1999 as an independent, publicly traded company, has its oscilloscope research and development division based in Colorado Springs. Intel had 250 employees in 2009. The Intel facility is now used for the centralized unemployment offices, social services, El Paso county offices, and a bitcoin mining facility. Microchip Technology (formerly Atmel), is a chip fabrication organization. The Apple Inc. facility was sold to Sanmina-SCI in 1996.",
"title": "Economy"
},
{
"paragraph_id": 28,
"text": "Almost immediately following the arrival of railroads beginning in 1871, the city's location at the base of Pikes Peak and the Rocky Mountains made it a popular tourism destination. Tourism is the third largest employer in the Pikes Peak region, accounting for more than 16,000 jobs. In 2018, 23 million day and overnight visitors came to the area, contributing $2.4 billion in revenue.",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 29,
"text": "Colorado Springs has more than 55 attractions and activities in the area, including Garden of the Gods park, United States Air Force Academy, the ANA Money Museum, Cheyenne Mountain Zoo, Colorado Springs Fine Arts Center at Colorado College, Old Colorado City, The National Museum of World War II Aviation, and the U.S. Olympic & Paralympic Training Center. In 2020, the U.S. Olympic & Paralympic Museum opened; the Flying W Ranch Chuckwagon Dinner & Western Show reopened in 2020. A new Pikes Peak Summit Complex opened at the 14,115-foot summit in 2021. The Manitou and Pikes Peak Railway also reopened in 2021.",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 30,
"text": "The downtown Colorado Springs Visitor Information Center offers free area information to leisure and business travelers. The Cultural Office of the Pikes Peak Region (COPPeR), also downtown, supports and advocates for the arts throughout the Pikes Peak Region. It operates the PeakRadar website to communicate city events.",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 31,
"text": "Colorado Springs is home to the annual Colorado Springs Labor Day Lift Off, a hot air balloon festival that takes place over Labor Day weekend at the city's Memorial Park.",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 32,
"text": "Other annual events include: a comic book convention and science fiction convention called GalaxyFest in February, a pride parade called PrideFest in July, the Greek Festival, the Pikes Peak Ascent and Marathon, and the Steers & Beers Whiskey and Beer Festival in August, and the Emma Crawford Coffin Races and Festival in nearby Manitou Springs and Arts Month in October.",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 33,
"text": "The Colorado Springs Festival of Lights Parade is held the first Saturday in December. The parade is held on Tejon Street in Downtown Colorado Springs.",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 34,
"text": "In 2017, Colorado had the third-most craft breweries at 348. Breweries and microbreweries have become popular in Colorado Springs, which hosts over 30 of them.",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 35,
"text": "Although houses of worship of almost every major world religion are within the city, Colorado Springs has in particular attracted a large influx of Evangelical Christians and Christian organizations in recent years. At one time Colorado Springs was the national headquarters for 81 different religious organizations, earning the city the tongue-in-cheek nicknames \"the Evangelical Vatican\" and \"The Christian Mecca.\"",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 36,
"text": "Religious groups with regional or international headquarters in Colorado Springs include:",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 37,
"text": "Although Colorado voters approved Colorado Amendment 64, a constitutional amendment in 2012 legalizing retail sales of marijuana for recreational purposes, the Colorado Springs city council voted not to permit retail shops in the city, as was allowed in the amendment. Medical marijuana outlets continue to operate in Colorado Springs. In 2015, there were 91 medical marijuana clinics in the city, which reported sales of $59.6 million in 2014, up 11 percent from the previous year but without recreational marijuana shops. On April 26, 2016, Colorado Springs city council decided to extend the current six-month moratorium to eighteen months with no new licenses to be granted until May 2017. A scholarly paper suggested the city would give up $25.4 million in tax revenue and fees if the city continued to thwart the industry from opening within the city limits. As of March 1, 2018, there were 131 medical marijuana centers and no recreational cannabis stores. As of 2019 Colorado Springs is still one of seven towns that have only allowed for medical marijuana.",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 38,
"text": "Colorado Springs has been the subject of or setting for many books, films and television shows, and is a frequent backdrop for political thrillers and military-themed stories because of its many military installations and vital importance to the United States' continental defense. Notable television series using the city as a setting include Dr. Quinn, Medicine Woman, Homicide Hunter and the Stargate series Stargate SG-1, as well as the films WarGames, The Prestige, and BlacKkKlansman.",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 39,
"text": "In a North Korean propaganda video released in April 2013, Colorado Springs was inexplicably singled out as one of four targets for a missile strike. The video failed to pinpoint Colorado Springs on the map, instead showing a spot somewhere in Louisiana.",
"title": "Culture and contemporary life"
},
{
"paragraph_id": 40,
"text": "Colorado Springs, dubbed Olympic City USA, is home to the United States Olympic & Paralympic Training Center and the headquarters of the United States Olympic & Paralympic Committee and the United States Anti-Doping Agency.",
"title": "Sports"
},
{
"paragraph_id": 41,
"text": "Further, over 50 national sports organizations (non-Olympic) headquarter in Colorado Springs. These include the National Strength and Conditioning Association, Sports Incubator, a various non-Olympic Sports (such as USA Ultimate), and more.",
"title": "Sports"
},
{
"paragraph_id": 42,
"text": "Colorado Springs and Denver hosted the 1962 World Ice Hockey Championships.",
"title": "Sports"
},
{
"paragraph_id": 43,
"text": "The city has a long association with the sport of figure skating, having hosted the U.S. Figure Skating Championships six times and the World Figure Skating Championships five times. It is home to the World Figure Skating Museum and Hall of Fame and the Broadmoor Skating Club, a notable training center for the sport. In recent years, the Broadmoor World Arena has hosted skating events such as Skate America and the Four Continents Figure Skating Championships.",
"title": "Sports"
},
{
"paragraph_id": 44,
"text": "Colorado Springs is home to 2 two professional baseball teams, The Rocky Mountain Vibes who are a member of the Pioneer League and are not affiliated with any MLB teams as of 2023, The Colorado Springs Snow Sox professional baseball team is based in Colorado Springs. The team is a member of the Pecos League, an independent baseball league which is not affiliated with Major or Minor League Baseball.",
"title": "Sports"
},
{
"paragraph_id": 45,
"text": "The Pikes Peak International Hill Climb (PPIHC), also known as The Race to the Clouds, is an annual invitational automobile and motorcycle hill climb to the summit of Pikes Peak, every year on the last Sunday of June. The highway wasn't completely paved until 2011.",
"title": "Sports"
},
{
"paragraph_id": 46,
"text": "The local colleges feature many sports teams. Notable among them are several nationally competitive NCAA Division I teams: United States Air Force Academy (Falcons) Football, Basketball and Hockey and Colorado College (Tigers) Hockey, and Women's Soccer.",
"title": "Sports"
},
{
"paragraph_id": 47,
"text": "Colorado Springs was the original headquarters of the Professional Bull Riders (PBR) from its founding in 1992 until 2005, when the organization was moved to Pueblo.",
"title": "Sports"
},
{
"paragraph_id": 48,
"text": "The city's Parks, Recreation and Cultural Services manage 136 neighborhood parks, eight community parks, seven regional parks, and five sports complexes, totaling 9,000 acres (3,600 ha). They also manage 500 acres (200 ha) of trails, of which 160 miles (260 km) are park trails and 105 miles (169 km) are urban. There are 5,000 acres (2,000 ha) of open space in 48 open-space areas.",
"title": "Parks, trails and open space"
},
{
"paragraph_id": 49,
"text": "Garden of the Gods is on Colorado Springs's western edge. It is a National Natural Landmark, with 300 foot (91 m) red/orange sandstone rock formations often viewed against a backdrop of the snow-capped Pikes Peak. This park is free to the public and offers many recreational opportunities, such as hiking, rock climbing, cycling, horseback riding and tours. It offers a variety of annual events, one of the most popular of which is the Starlight Spectacular, a recreational bike ride held every summer to benefit the Trails and Open Space Coalition of Colorado Springs.",
"title": "Parks, trails and open space"
},
{
"paragraph_id": 50,
"text": "Colorado Springs has several major city parks, such as Palmer Park, America the Beautiful Park in downtown, Memorial Park, which includes many sports fields, an indoor swimming pool and skating rink, a skateboard bowl and two half-pipes, and Monument Valley Park, which has walking and biking paths, an outdoor swimming pool and pickleball courts. Monument Valley Park also has Tahama Spring, the original spring in Colorado Springs. Austin Bluffs Park affords a place of recreation in eastern Colorado Springs. El Paso County Regional Parks include Bear Creek Regional Park, Bear Creek Dog Park, Fox Run Regional Park and Fountain Creek Regional Park and Nature Center. Ponderosa pine (Pinus ponderosa), Gambel oak (Quercus gambelii), narrowleaf yucca (Yucca angustissima, syn. Yucca glauca) and prickly pear cactus (Opuntia macrorhiza).",
"title": "Parks, trails and open space"
},
{
"paragraph_id": 51,
"text": "Three trails, the New Santa Fe Regional Trail, Pikes Peak Greenway and Fountain Creek Regional Trail, form a continuous path from Palmer Lake, through Colorado Springs, to Fountain, Colorado. The majority of the trail between Palmer Lake and Fountain is a soft surface breeze gravel trail. A major segment of the trail within the Colorado Springs city limits is paved. The trails, except Monument Valley Park trails, may be used for equestrian traffic. Motorized vehicles are not allowed on the trails. Many of the trails are interconnected, having main spine trails, like the Pikes Peak Greenway, that lead to secondary trails.",
"title": "Parks, trails and open space"
},
{
"paragraph_id": 52,
"text": "On November 2, 2010, Colorado Springs voters adopted a council-strong mayor form of government. The City of Colorado Springs transitioned to the new system of government in 2011. Under the council-strong mayor system of government, the mayor is the chief executive and the city council is the legislative branch. The mayor is a full-time elected position and not a member of the council. The council has nine members, six of whom represent one of six equally populated districts each. The remaining three members are elected at-large.",
"title": "Government"
},
{
"paragraph_id": 53,
"text": "Colorado Springs City Hall was built from 1902 to 1904 on land donated by W. S. Stratton.",
"title": "Government"
},
{
"paragraph_id": 54,
"text": "The Colorado Springs City Council consists of nine elected officials, six of whom represent districts and three of whom represent the city at-large.",
"title": "Government"
},
{
"paragraph_id": 55,
"text": "In 2017 Caleb Hannan wrote in Politico that Colorado Springs was \"staunchly Republican\", \"a right-wing counterweight to liberal Boulder\", and that a study ranked it \"the fourth most conservative city in America\". In 2016 Hannan wrote that downtown Colorado Springs had a different political vibe from the overall area's and that there were \"superficial signs of changing demographics\". Since 2020, Colorado Springs has continued to shift towards the political center. In 2022, Governor Jared Polis won the city in his bid for reelection. In the 2023 mayoral election, independent candidate Yemi Mobolade handily won the race and became the first elected non-Republican mayor of the city.",
"title": "Government"
},
{
"paragraph_id": 56,
"text": "In addition the state of Colorado runs the Colorado School for the Deaf and Blind, a residential school for people up to age 21 and established in 1874, in the city.",
"title": "Education"
},
{
"paragraph_id": 57,
"text": "State institutions offering bachelors and graduate degree programs in Colorado Springs include University of Colorado Colorado Springs (UCCS) with more than 12,000 students, and, Pikes Peak State College which offers mostly two-year degree associate degrees. The United States Air Force Academy is a federal institution offering bachelor's degrees for officer candidates.",
"title": "Education"
},
{
"paragraph_id": 58,
"text": "Private non-profit institutions include Colorado College established in 1874 with about 2,000 undergraduates. Colorado Christian University has its Colorado Springs Center in the city.",
"title": "Education"
},
{
"paragraph_id": 59,
"text": "Private for-profit institutions include Colorado Technical University whose main campus is in Colorado Springs and IntelliTec College a technical training school.",
"title": "Education"
},
{
"paragraph_id": 60,
"text": "Colorado Springs is primarily served by one interstate highway. I-25 runs north and south through Colorado, and traverses the city for nearly 18 miles (29 km), entering the city south of Circle Drive and exiting north of North Gate Boulevard. In El Paso County it is known as Ronald Reagan Highway.",
"title": "Transportation"
},
{
"paragraph_id": 61,
"text": "A number of state and U.S. highways serve the city. State Highway 21 is a major east side semi-expressway from Black Forest to Fountain, known locally and co-signed as Powers Boulevard. State Highway 83 runs north–south from central Denver to northern Colorado Springs. State Highway 94 runs east–west from western Cheyenne County to eastern Colorado Springs where it terminates at US 24. US 24 is a major route through the city and county, providing access to Woodland Park via Ute Pass to the west and downtown, Nob Hill and numerous suburbs to the east. It is co-signed with Platte Ave after SH 21 and originally carried local traffic through town. The Martin Luther King Jr Bypass runs from I-25 near Circle Drive along Fountain Blvd to SH 21, then east again. State Highway 115 begins in Cañon City, traveling north along the western edge of Fort Carson; when it reaches the city limits it merges with Nevada Avenue, a signed Business Route of US 85. US 85 and SH 115 are concurrent between Lake Avenue and I-25. US 85 enters the city at Fountain and was signed at Venetucci Blvd, Lake Avenue, and Nevada Avenue at various points in history; however most of US 85 is concurrent with I-25 and is not signed.",
"title": "Transportation"
},
{
"paragraph_id": 62,
"text": "In November 2015, voters in Colorado Springs overwhelmingly passed ballot measure 2C, dedicating funds from a temporary sales tax increase to much needed road and infrastructure improvements over five years. This temporary increase is estimated to bring in approximately $50 million annually, which will be used solely to improve roads and infrastructure. The ballot measure passed by a margin of approximately 65–35%.",
"title": "Transportation"
},
{
"paragraph_id": 63,
"text": "In 2004, the voters of Colorado Springs and El Paso County established the Pikes Peak Rural Transportation Authority.",
"title": "Transportation"
},
{
"paragraph_id": 64,
"text": "In early 2010, the city of Colorado Springs approved an expansion of the northernmost part of Powers Boulevard in order to create an Interstate 25 bypass commonly referred to as the Copper Ridge Expansion.",
"title": "Transportation"
},
{
"paragraph_id": 65,
"text": "Colorado Springs Airport (COS; ICAO: KCOS) has been in operation since 1925. It is the second-largest commercial airport in the state, after Denver International Airport (DEN; ICAO: KDEN). It covers 7,200 acres (2,900 ha) of land at an elevation of approximately 6,200 feet (1,900 m). COS is considered to be a joint-use civilian and military airport, as Peterson Space Force Base is a tenant of the airport. It has three paved runways: 17L/35R is 13,501 by 150 feet (4,115 by 46 m), the runway 17R/35L is 11,022 by 150 feet (3,360 by 46 m) and the runway 13/31 is 8,270 by 150 feet (2,521 by 46 m). The airport handled 2,134,618 passengers in 2022, and is served by American, Avelo, Delta, Southwest, Sun Country, and United.",
"title": "Transportation"
},
{
"paragraph_id": 66,
"text": "Freight service is provided by Union Pacific and BNSF.",
"title": "Transportation"
},
{
"paragraph_id": 67,
"text": "Once an important hub, the city was once served by four Class 1 railroads, as well as a number of smaller operators, some of which were narrow gauge, and an extensive streetcar system, the Colorado Springs and Interurban Railway .",
"title": "Transportation"
},
{
"paragraph_id": 68,
"text": "Currently there is no intercity passenger service; the last remaining services connecting the Front Range cities ceased with the formation of Amtrak in 1971 . Front Range Passenger Rail is a current proposal (as of 2023) to link the cities from Pueblo in the south, north to Fort Collins and possibly Cheyenne, Wyoming.",
"title": "Transportation"
},
{
"paragraph_id": 69,
"text": "In April 2018, the Colorado Springs City Council approved a Bike Master Plan. The vision of the city's Bike Master Plan is \"a healthy and vibrant Colorado Springs where bicycling is one of many transportation options for a large portion of the population, and where a well-connected and well-maintained network of urban trails, single-track, and on-street infrastructure offers a bicycling experience for present and future generations that is safe, convenient, and fun for getting around, getting in shape, or getting away.\" Bike lanes in Colorado Springs have not been deployed without controversy. According to The Gazette, their readers \"have mixed feelings for new bike lanes.\" In December 2016, the City removed a bike lane along Research Parkway due to overwhelming opposition; an online survey found that 80.5% of respondents opposed the bike lane. The Gazette has stated that since the Bike Master Plan was adopted by city council, \"no issue has elicited more argument in The Gazette pages,\" and due to this immense public interest, on February 25, 2019, The Gazette hosted a town hall meeting called \"Battle of the Bike Lanes.\"",
"title": "Transportation"
},
{
"paragraph_id": 70,
"text": "A 2011 study by Walk Score ranked Colorado Springs 34th most walkable of fifty largest U.S. cities.",
"title": "Transportation"
},
{
"paragraph_id": 71,
"text": "Mountain Metropolitan Transit (MMT) is testing Battery Electric Buses (BEB), and if the buses perform well, the agency plans to acquire its first three BEBs in 2021 using funds from the Volkswagen emissions scandal and resulting lawsuit and settlement. On April 22, 2022, Mountain Metro unveiled four new all-electric Proterra ZX5 buses to be added to their fleet. The new buses join their current fleet of 67 clean diesel buses. They are funded by the Colorado Department of Transportation Division of Transit and Rail Settlement Transit Bus Replacement Program, Volkswagen Diesel Emission Settlement trust, and Federal transit Administration 5339(b) Buses and Bus Facilities Program grant. The Proterra ZX5 buses run 220 to 330 miles on a single charge, and cost $1.2 million per bus.",
"title": "Transportation"
},
{
"paragraph_id": 72,
"text": "Mountain Metro Mobility is an Americans with Disabilities Act (ADA) federally mandated complementary ADA paratransit service, which provides demand-response service for individuals with mobility needs that prevent them from using the fixed-route bus system.",
"title": "Transportation"
},
{
"paragraph_id": 73,
"text": "Mountain Metro Rides offers alternative transportation options to residents of the Pikes Peak Region. The program is designed to reduce congestion and pollution by encouraging people to commute by carpool, vanpool, bicycling or walking.",
"title": "Transportation"
},
{
"paragraph_id": 74,
"text": "Bustang provides intercity transportation to Colorado Springs. It is part of the South and Outrider lines, which connect to Denver and to Lamar. There is an additional line that connects Colorado Springs directly to the Denver Tech Center.",
"title": "Transportation"
},
{
"paragraph_id": 75,
"text": "See also National Register of Historic Places in Colorado Springs, Colorado",
"title": "Neighborhoods and Historic Places"
},
{
"paragraph_id": 76,
"text": "Colorado Springs' sister cities are:",
"title": "Sister cities"
},
{
"paragraph_id": 77,
"text": "Colorado Springs's sister city organization began when it became partners with Fujiyoshida. The torii gate erected to commemorate the relationship stands at the corner of Bijou Street and Nevada Avenue, and is one of the city's most recognizable landmarks. The torii gate, crisscrossed bridge and shrine, in the median between Platte and Bijou Streets downtown, were a gift to Colorado Springs, erected in 1966 by the Rotary Club of Colorado Springs to celebrate the friendship between the two communities. A plaque near the torii gate states that \"the purpose of the sister city relationship is to promote understanding between the people of our two countries and cities\". The Fujiyoshida Student exchange program has become an annual event.",
"title": "Sister cities"
},
{
"paragraph_id": 78,
"text": "In 2006 and 2010, the Bankstown TAP (Talent Advancement Program) performed with the Youth Symphony and the Colorado Springs Children's Chorale as part of the annual \"In Harmony\" program. A notable similarity between Colorado Springs and its sister cities is their geographic positions: three of the seven cities are near the foot of a major mountain or mountain range, as is Colorado Springs.",
"title": "Sister cities"
}
] | Colorado Springs is a home rule municipality in and the county seat of El Paso County, Colorado, United States. It is the most populous city in El Paso County, with a population of 478,961 at the 2020 census, a 15.02% increase since 2010. Colorado Springs is the second-most populous city and the most extensive city in the state of Colorado, and the 39th-most populous city in the United States. It is the principal city of the Colorado Springs metropolitan area and the second-most prominent city of the Front Range Urban Corridor. It is located in east-central Colorado on Fountain Creek, 70 miles (113 km) south of Denver. At 6,035 feet (1,839 m) the city stands over 1 mile (1.6 km) above sea level. Colorado Springs is near the base of Pikes Peak, which rises 14,115 feet (4,302.31 m) above sea level on the eastern edge of the Southern Rocky Mountains. The city is the largest city north of Mexico above 6000 feet in elevation. | 2001-09-14T18:42:23Z | 2023-12-29T05:20:42Z | [
"Template:Div col end",
"Template:Portal",
"Template:Cite web",
"Template:Colorado county seats",
"Template:Main",
"Template:R",
"Template:US Census population",
"Template:Further",
"Template:Rp",
"Template:Efn",
"Template:Citation",
"Template:Legend inline",
"Template:Notelist",
"Template:Cbignore",
"Template:Update inline",
"Template:Clear left",
"Template:Col-begin",
"Template:Cite book",
"Template:Short description",
"Template:Use mdy dates",
"Template:Convert",
"Template:Ndash",
"Template:Cite news",
"Template:Cite journal",
"Template:USPopulousCities",
"Template:Dead link",
"Template:Authority control",
"Template:Col-break",
"Template:Col-end",
"Template:Webarchive",
"Template:El Paso County, Colorado",
"Template:Infobox settlement",
"Template:Weather box",
"Template:Clear",
"Template:Snds",
"Template:Colorado",
"Template:Sister project links",
"Template:Mining in Colorado Springs",
"Template:Tooltip",
"Template:Flagicon",
"Template:Cite magazine",
"Template:Div col",
"Template:See also",
"Template:Reflist",
"Template:Cite report",
"Template:TOC limit",
"Template:For timeline",
"Template:Nbsp",
"Template:As of",
"Template:Colorado Springs",
"Template:Colorado cities and mayors of 100,000 population"
] | https://en.wikipedia.org/wiki/Colorado_Springs,_Colorado |
6,251 | Professional certification | Professional certification, trade certification, or professional designation, often called simply certification or qualification, is a designation earned by a person to assure qualification to perform a job or task. Not all certifications that use post-nominal letters are an acknowledgement of educational achievement, or an agency appointed to safeguard the public interest.
A certification is a third-party attestation of an individual's level of knowledge or proficiency in a certain industry or profession. They are granted by authorities in the field, such as professional societies and universities, or by private certificate-granting agencies. Most certifications are time-limited; some expire after a period of time (e.g., the lifetime of a product that required certification for use), while others can be renewed indefinitely as long as certain requirements are met. Renewal usually requires ongoing education to remain up-to-date on advancements in the field, evidenced by earning the specified number of continuing education credits (CECs), or continuing education units (CEUs), from approved professional development courses.
Many certification programs are affiliated with professional associations, trade organizations, or private vendors interested in raising industry standards. Certification programs are often created or endorsed by professional associations, but are typically completely independent from membership organizations. Certifications are very common in fields such as aviation, construction, technology, environment, and other industrial sectors, as well as healthcare, business, real estate, and finance.
According to The Guide to National Professional Certification Programs (1997) by Phillip Barnhart, "certifications are portable, since they do not depend on one company's definition of a certain job" and they provide potential employers with "an impartial, third-party endorsement of an individual's professional knowledge and experience".
Certification is different from professional licensure. In the United States, licenses are typically issued by state agencies, whereas certifications are usually awarded by professional societies or educational institutes. Obtaining a certificate is voluntary in some fields, but in others, certification from a government-accredited agency may be legally required to perform certain jobs or tasks. In other countries, licenses are typically granted by professional societies or universities and require a certificate after about three to five years and so on thereafter. The assessment process for certification may be more comprehensive than that of licensure, though sometimes the assessment process is very similar or even the same, despite differing in terms of legal status.
The American National Standards Institute (ANSI) defines the standard for being a certifying agency as meeting the following two requirements:
The Institute for Credentialing Excellence (ICE) is a U.S.-based organization that sets standards for the accreditation of personnel certification and certificate programs based on the Standards for Educational and Psychological Testing, a joint publication of the American Educational Research Association (AERA), the American Psychological Association (APA), and the National Council on Measurement in Education (NCME). Many members of the Association of Test Publishers (ATP) are also certification organizations.
There are three general types of certification. Listed in order of development level and portability, they are: corporate (internal), product-specific, and profession-wide.
Corporate, or "internal" certifications, are made by a corporation or low-stakes organization for internal purposes. For example, a corporation might require a one-day training course for all sales personnel, after which they receive a certificate. While this certificate has limited portability – to other corporations, for example – it is the most simple to develop.
Product-specific certifications are more involved, and are intended to be referenced to a product across all applications. This approach is very prevalent in the information technology (IT) industry, where personnel are certified on a version of software or hardware. This type of certification is portable across locations (for example, different corporations that use that software), but not across other products. Another example could be the certifications issued for shipping personnel, which are under international standards even for the recognition of the certification body, under the International Maritime Organization (IMO).
The most general type of certification is profession-wide. Certification in the medical profession is often offered by particular specialties. In order to apply professional standards, increase the level of practice, and protect the public, a professional organization might establish a certification. This is intended to be portable to all places a certified professional might work. Of course, this generalization increases the cost of such a program; the process to establish a legally defensible assessment of an entire profession is very extensive. An example of this is a certified public accountant (CPA), which would not be certified for just one corporation or one piece of accountancy software but for general work in the profession.
Many tertiary education providers grant professional certificates as an award for the completion of an educational program. The curriculum of a professional certificate is most often in a focused subject matter. Many professional certificates have the same curriculum as master's degrees in the same subject. Many other professional certificates offer the same courses as master's degrees in the same subject, but require the student to take fewer total courses to complete the program. Some professional certificates have a curriculum that more closely resembles a baccalaureate major in the same field. The typical professional certificate program is between 200 and 300 class-hours in size. It is uncommon for a program to be larger or smaller than that. Most professional certificate programs are open enrollment, but some have admissions processes. A few universities put some of their professional certificates into a subclass they refer to as advanced professional certificates.
Some of the more commonly offered professional certificates include:
Advanced professional certificates are professional credentials designed to help professionals enhance their job performance and marketability in their respective fields. In many other countries, certificates are qualifications in higher education. In the United States, a certificate may be offered by an institute of higher education. These certificates usually signify that a student has reached a standard of knowledge of a certain vocational subject. Certificate programs can be completed more quickly than associate degrees and often do not have general education requirements.
An advanced professional certificate is a result of an educational process designed for individuals. Certificates are designed for both newcomers to the industry as well as seasoned professionals. Certificates are awarded by an educational program or academic institution. Completion of a certificate program indicates completion of a course or series of courses with a specific concentration that is different from an educational degree program. Course content for an advanced certificate is set forth through a variety of sources i.e. faculty, committee, instructors, and other subject matter experts in a related field. The end goal of an advanced professional certificate is so that professionals may demonstrate knowledge of course content at the end of a set period in time.
There are many professional bodies for accountants and auditors throughout the world; some of them are legally recognized in their jurisdictions. Public accountants are the accountancy and control experts that are legally certified in different jurisdictions to work in public practices, certifying accounts as statutory auditors, eventually selling advice and services to other individuals and businesses. Today, however, many work within private corporations, financial industry, and government bodies.
Cf. Accountancy qualifications and regulation
Aviators are certified through theoretical and in-flight examinations. Requirements for certifications are quite equal in most countries and are regulated by each National Aviation Authority. The existing certificates or pilot licenses are:
Licensing in these categories require not only examinations but also a minimum number of flight hours. All categories are available for Fixed-Wing Aircraft (airplanes) and Rotatory-Wing Aircraft (helicopters). Within each category, aviators may also obtain certifications in:
Usually, aviators must be certified also in their log books for the type and model of aircraft they are allowed to fly. Currency checks as well as regular medical check-ups with a frequency of 6 months, 12 months, or 36 months, depending on the type of flying permitted, are obligatory. An aviator can fly only if holding:
In Europe, the ANSP, ATCO & ANSP technicians are certified according to EUROCONTROL Safety Regulatory Requirement (ESARRs) (according to EU regulation 2096/2005 "Common Requirements").
In the United States, several communications certifications are conferred by the Electronics Technicians Association.
Certification is often used in the professions of software engineering and information technology.
Conferred by the International Dance Council CID at UNESCO, the International Certification of Dance Studies is awarded to students who have completed 150 hours of classes in a specific form of dance for Level 1. Another 150 hours are required for Level 2 and so on till Level 10. This is the only international certification for dance since the International Dance Council CID is the official body for all forms of dance; it is usually given in addition to local or national certificates, that is why it is colloquially called "the dancer's passport". Students cannot apply for this certification directly – they have to ask their school to apply on their behalf. This certification is awarded free of charge, there is no cost other than membership fees.
International Dance Council CID at UNESCO administers the International Certification of Dance Studies.
In the United States, several electronics certifications are provided by the Electronics Technicians Association.
The Federal Emergency Management Agency's EMI offers credentials and training opportunities for United States citizens. Students do not have to be employed by FEMA or be federal employees for some of the programs.
Professional engineering is any act of planning, designing, composing, measuring, evaluating, inspecting, advising, reporting, directing or supervising, or managing any of the foregoing, that requires the application of engineering principles and that concerns the safeguarding of life, health, property, economic interests, the public interest or the environment.
Event planning includes budgeting, scheduling, site selection, acquiring necessary permits, coordinating transportation and parking, arranging for speakers or entertainers, arranging decor, event security, catering, coordinating with third-party vendors, and emergency plans.
Common event planning certifications include:
Facility management can be defined as an aspect of engineering management science that deals with the planning, designing, coordination of space and maintenance of a built environment to enhance quality service management system. Service Quality System includes activities like security, maintenance, catering, and external as well as internal cleaning. In general, it is also the coordination and harmonization of various specialist disciplines to create the best possible working environment for staff.
Facility management is an interdisciplinary field devoted to the coordination of space, infrastructure, people and organization, often associated with the administration of office blocks, arenas, schools, convention centers, shopping complexes, hospitals, hotels, etc. However, FM facilitates on a wider range of activities than just business services and these are referred to as non-core functions.
A warehouse management system (WMS) is a part of the supply chain and primarily aims to control the movement and storage of materials within a warehouse and process the associated transactions, including shipping, receiving, putaway and picking. The systems also direct and optimize stock putaway based on real-time information about the status of bin utilization. A WMS monitors the progress of products through the warehouse. It involves the physical warehouse infrastructure, tracking systems, and communication between product stations.
More precisely, warehouse management involves the receipt, storage and movement of goods, (normally finished goods), to intermediate storage locations or to a final customer. In the multi-echelon model for distribution, there may be multiple levels of warehouses. This includes a central warehouse, a regional warehouses (serviced by the central warehouse) and potentially retail warehouses (serviced by the regional warehouses).
IECEx covers the specialized field of explosion protection associated with the use of equipment in areas where flammable gases, liquids and combustible dusts may be present. This system provides the assurance that equipment is manufactured to meet safety standards, and that services such as installation, repair and overhaul also comply with IEC International Standards on 60079 series. The UNECE (United Nations Economic Commission for Europe), cited IECEx as one example of a practice model for the verification of conformity to IEC Standards, for European smaller countries with no certification schemes for such equipment. It published a "Common Regulatory Framework" as a suggestion for those countries implementing a certification program for the explosive atmospheres' segment.
In the United States, insurance professionals are licensed separately by each state. Many individuals seek one or more certifications to distinguish themselves from their peers.
TESOL is a large field of employment with widely varying degrees of regulation. Most provision worldwide is through the state school system of each individual country, and as such, the instructors tend to be trained primary- or secondary school teachers who are native speakers of the language of their pupils, and not of English. Though native speakers of English have been working in non-English speaking countries in this capacity for years, it was not until the last twenty-five years or so that there was any widespread focus on training particularly for this field. Previously, workers in this sort of job were people engaging in backpacker tourism hoping to earn some extra travel money or well-educated professionals in other fields volunteering, or retired people. These sort of people are certainly still to be found, but there are many who consider TESOL their main profession.
One of the problems facing these full-time teachers is the absence of an international governing body for the certification or licensure of English language teachers. However, Cambridge University and its subsidiary body UCLES are pioneers in trying to get some degree of accountability and quality control to consumers of English courses, through their CELTA and DELTA programs. Trinity College London has equivalent programs, the CertTESOL and the LTCL DipTESOL. They offer initial certificates in teaching, in which candidates are trained in language awareness and classroom techniques, and given a chance to practice teaching, after which feedback is reported. Both institutions have as a follow-up a professional diploma, usually taken after a year or two in the field. Although the initial certificate is available to anyone with a high school education, the diploma is meant to be a post-graduate qualification and can in fact be incorporated into a master's degree program.
An increasing number of attorneys are choosing to be recognized as having special expertise in certain fields of law. According to the American Bar Association, a lawyer who is a certified specialist has been recognized by an independent professional certifying organization as having an enhanced level of skill and expertise, as well as substantial involvement in an established legal specialty. These organizations require a lawyer to demonstrate special training, experience and knowledge to ensure that the lawyer's recognition is meaningful and reliable. Lawyer conduct with regard to specialty certification is regulated by the states.
Legal administrators vary in their day-to-day responsibilities and job requirements. The Association of Legal Administrators (ALA) is the credentialing body of the Certified Legal Manager (CLM) certification program. CLMs are recognized as administrators who have passed a comprehensive examination and have met other eligibility requirements.:
In Australia, ALIA (Australian Library and Information Association) certifies librarians and library technicians. Distinguished librarians who have completed a high level of professional learning are awarded the Distinguished Certified Professional Award. Prior to 2013, this award was known as Associate Fellows.
In New Zealand, the accrediting body is LIANZA (Library and Information Association of New Zealand Aotearoa Te Rau Herenga O Aotearoa). LIANZA accredit prominent librarians at three levels, Fellows, Life Members and Associates.
Logistician is the profession in the logistics and transport sectors, including sea, air, land and rail modes. Professional qualification for logisticians usually carries post-nominal letters.
Certification granting bodies include, but are not limited to, Institute for Supply Management (ISM), Association for Operations Management (APICS), Chartered Institute of Logistics and Transport (CILT), International Society of Logistics (SOLE), Canadian Institute of Traffic and Transportation (CITT), and Allied Council for Commerce and Logistics (ACCL).
Management consulting is the practice of providing consulting services to organizations to improve their performance or in any way to assist in achieving any sort of organizational objectives.
The profession's primary certification is the "Certified Management Consultant" (CMC) designation.
Certification granting bodies are the approximately 50 Institutes of Management Consulting belonging to the International Council of Management Consulting Institutes (ICMCI).
Churches have their own process of who may use various religious titles. Protestant churches typically require a Masters of Divinity, accreditation by the denomination and ordination by the local church in order for a minister to become a "Reverend". Those qualifications may or may not also give government authorization to solemnize marriages.
Board certification is the process by which a physician in the United States documents by written, practical or computer based testing, illustrating a mastery of knowledge and skills that define a particular area of medical specialization. The American Board of Medical Specialties, a not-for-profit organization, assists 24 approved medical specialty boards in the development and use of standards in the ongoing evaluation and certification of physicians.
Medical specialty certification in the United States is a voluntary process. While medical licensure sets the minimum competency requirements to diagnose and treat patients, it is not specialty specific. Board certification demonstrates a physician's exceptional expertise in a particular specialty or sub-specialty of medical practice.
Patients, physicians, health care providers, insurers and quality organizations regard certification as an important measure of a physician's knowledge, experience and skills to provide quality health care within a given specialty.
Other professional certifications include certifications such as medical licenses, Membership of the Royal College of Physicians, Fellowship of the Royal College of Physicians and Surgeons of Canada, nursing board certification, diplomas in social work. The Commission for Certification in Geriatric Pharmacy certifies pharmacists that are knowledgeable about principles of geriatric pharmacotherapy and the provision of pharmaceutical care to the elderly. Additional certifying bodies relating to the medical field include:
NCPRP stands for "National Certified Peer Recovery Professional", and the NCPRP credential and exam were developed in collaboration with the International Certification Board of Recovery Professionals (ICBRP) and is currently being administered by PARfessionals.
PARfessionals is a professional organization and all of the available courses are professional development and pre-certification courses.
The NCPRP credential and exam focus primarily on the concept of peer recovery through mental health and addiction recovery. It has the main purpose of training student-candidates on how to become peer recovery professionals who can provide guidance, knowledge or assistance for individuals who have had similar experiences.
Each student-candidate must complete several key steps which include initial registration; the pre-certification review course; and all applicable sections of the official application in order to become eligible to complete the final step, which is the NCPRP certification exam.
The NCPRP credential is obtained once a participant successfully passes the NCPRP certification exam by the second attempt and is valid for five years.
Organizations that offer various certifications include:
National Board of Public Health Examiners, www.nbphe.org
In the US, the Universal Accreditation Board, an organization composed of the Public Relations Society of America, the Agricultural Relations Council, the National School Public Relations Association, the Religious Communicators Council and other public relations professional societies, administers the Accreditation in Public Relations (APR), a voluntary certification program for public relations practitioners.
The Certified Public Participation Professional (CP3) and Master Certified Public Participation Professional (MCP3) are awarded by two regions of the International Association for Public Participation (IAP2) Archived 17 August 2019 at the Wayback Machine: IAP2 Canada and IAP2 USA. As of 2019, only 25 individuals had achieved either of these distinctions. The CP3 designation is awarded upon successfully completing a three-step process that includes a written application documenting the individual's experience in the profession, a written response to a case study, and an in-person oral assessment.
Individuals seeking certification are assessed against 5 Core Competencies, which are the essential capabilities for a professional in this field to effectively design, implement, and evaluate public participation programs. The competencies emerged from qualitative analysis of a comprehensive list of knowledge, attitudes, beliefs, skills, behaviors, and capabilities identified in June 2014 by more than 100 P2 professionals from around the world. The descriptions and quality standards for each competency were developed, tested, and refined through an iterative process involving IAP2 members. Each competency is further divided into individual criteria. An individual must meet or exceed every criterion to achieve the CP3 designation. IAP2 USA's program includes 29 criteria. IAP2 Canada's program includes 31 criteria; the two additional criteria in Canada address federal requirements for indigenous engagement. The MCP3 designation recognizes additional specialization and expertise and is assessed through a written application available only to individuals who have already achieved the CP3 designation.
To maintain professional certification, individuals must maintain active membership in IAP2, provide a minimum of 20 hours (annually) of volunteer (unpaid) service to IAP2, and participate in a minimum of 12 hours (annually) of continued professional development.
The Building Owners and Managers Association and the International Facility Management Association offer professional certifications for the operation and management of commercial properties.
Organizations offering certification include:
Conferred by the National Speakers Association, the Certified Speaking Professional (CSP) is the speaking profession's international measure of professional platform competence. This certification is awarded by the National Speakers Association. Only about 10% of the speakers who belong to the Global Speakers Federation (GSF) hold this designation. Those who have earned their certification have done so by demonstrating a track record of experience and expertise.
Political commentators have criticized professional or occupational licensing, especially medical and legal licensing, for restricting the supply of services and therefore making them more expensive, often putting them out of reach of the poor.
The proliferation of IT certifications (both offered and attained) has led some technologists to question their value. Proprietary content that has been distributed on the Internet allows some to gain credentials without the implied depth or breadth of expertise. | [
{
"paragraph_id": 0,
"text": "Professional certification, trade certification, or professional designation, often called simply certification or qualification, is a designation earned by a person to assure qualification to perform a job or task. Not all certifications that use post-nominal letters are an acknowledgement of educational achievement, or an agency appointed to safeguard the public interest.",
"title": ""
},
{
"paragraph_id": 1,
"text": "A certification is a third-party attestation of an individual's level of knowledge or proficiency in a certain industry or profession. They are granted by authorities in the field, such as professional societies and universities, or by private certificate-granting agencies. Most certifications are time-limited; some expire after a period of time (e.g., the lifetime of a product that required certification for use), while others can be renewed indefinitely as long as certain requirements are met. Renewal usually requires ongoing education to remain up-to-date on advancements in the field, evidenced by earning the specified number of continuing education credits (CECs), or continuing education units (CEUs), from approved professional development courses.",
"title": "Overview"
},
{
"paragraph_id": 2,
"text": "Many certification programs are affiliated with professional associations, trade organizations, or private vendors interested in raising industry standards. Certification programs are often created or endorsed by professional associations, but are typically completely independent from membership organizations. Certifications are very common in fields such as aviation, construction, technology, environment, and other industrial sectors, as well as healthcare, business, real estate, and finance.",
"title": "Overview"
},
{
"paragraph_id": 3,
"text": "According to The Guide to National Professional Certification Programs (1997) by Phillip Barnhart, \"certifications are portable, since they do not depend on one company's definition of a certain job\" and they provide potential employers with \"an impartial, third-party endorsement of an individual's professional knowledge and experience\".",
"title": "Overview"
},
{
"paragraph_id": 4,
"text": "Certification is different from professional licensure. In the United States, licenses are typically issued by state agencies, whereas certifications are usually awarded by professional societies or educational institutes. Obtaining a certificate is voluntary in some fields, but in others, certification from a government-accredited agency may be legally required to perform certain jobs or tasks. In other countries, licenses are typically granted by professional societies or universities and require a certificate after about three to five years and so on thereafter. The assessment process for certification may be more comprehensive than that of licensure, though sometimes the assessment process is very similar or even the same, despite differing in terms of legal status.",
"title": "Overview"
},
{
"paragraph_id": 5,
"text": "The American National Standards Institute (ANSI) defines the standard for being a certifying agency as meeting the following two requirements:",
"title": "Overview"
},
{
"paragraph_id": 6,
"text": "The Institute for Credentialing Excellence (ICE) is a U.S.-based organization that sets standards for the accreditation of personnel certification and certificate programs based on the Standards for Educational and Psychological Testing, a joint publication of the American Educational Research Association (AERA), the American Psychological Association (APA), and the National Council on Measurement in Education (NCME). Many members of the Association of Test Publishers (ATP) are also certification organizations.",
"title": "Overview"
},
{
"paragraph_id": 7,
"text": "There are three general types of certification. Listed in order of development level and portability, they are: corporate (internal), product-specific, and profession-wide.",
"title": "Categorization"
},
{
"paragraph_id": 8,
"text": "Corporate, or \"internal\" certifications, are made by a corporation or low-stakes organization for internal purposes. For example, a corporation might require a one-day training course for all sales personnel, after which they receive a certificate. While this certificate has limited portability – to other corporations, for example – it is the most simple to develop.",
"title": "Categorization"
},
{
"paragraph_id": 9,
"text": "Product-specific certifications are more involved, and are intended to be referenced to a product across all applications. This approach is very prevalent in the information technology (IT) industry, where personnel are certified on a version of software or hardware. This type of certification is portable across locations (for example, different corporations that use that software), but not across other products. Another example could be the certifications issued for shipping personnel, which are under international standards even for the recognition of the certification body, under the International Maritime Organization (IMO).",
"title": "Categorization"
},
{
"paragraph_id": 10,
"text": "The most general type of certification is profession-wide. Certification in the medical profession is often offered by particular specialties. In order to apply professional standards, increase the level of practice, and protect the public, a professional organization might establish a certification. This is intended to be portable to all places a certified professional might work. Of course, this generalization increases the cost of such a program; the process to establish a legally defensible assessment of an entire profession is very extensive. An example of this is a certified public accountant (CPA), which would not be certified for just one corporation or one piece of accountancy software but for general work in the profession.",
"title": "Categorization"
},
{
"paragraph_id": 11,
"text": "Many tertiary education providers grant professional certificates as an award for the completion of an educational program. The curriculum of a professional certificate is most often in a focused subject matter. Many professional certificates have the same curriculum as master's degrees in the same subject. Many other professional certificates offer the same courses as master's degrees in the same subject, but require the student to take fewer total courses to complete the program. Some professional certificates have a curriculum that more closely resembles a baccalaureate major in the same field. The typical professional certificate program is between 200 and 300 class-hours in size. It is uncommon for a program to be larger or smaller than that. Most professional certificate programs are open enrollment, but some have admissions processes. A few universities put some of their professional certificates into a subclass they refer to as advanced professional certificates.",
"title": "Professional certificates awarded by tertiary education providers"
},
{
"paragraph_id": 12,
"text": "Some of the more commonly offered professional certificates include:",
"title": "Professional certificates awarded by tertiary education providers"
},
{
"paragraph_id": 13,
"text": "Advanced professional certificates are professional credentials designed to help professionals enhance their job performance and marketability in their respective fields. In many other countries, certificates are qualifications in higher education. In the United States, a certificate may be offered by an institute of higher education. These certificates usually signify that a student has reached a standard of knowledge of a certain vocational subject. Certificate programs can be completed more quickly than associate degrees and often do not have general education requirements.",
"title": "Professional certificates awarded by tertiary education providers"
},
{
"paragraph_id": 14,
"text": "An advanced professional certificate is a result of an educational process designed for individuals. Certificates are designed for both newcomers to the industry as well as seasoned professionals. Certificates are awarded by an educational program or academic institution. Completion of a certificate program indicates completion of a course or series of courses with a specific concentration that is different from an educational degree program. Course content for an advanced certificate is set forth through a variety of sources i.e. faculty, committee, instructors, and other subject matter experts in a related field. The end goal of an advanced professional certificate is so that professionals may demonstrate knowledge of course content at the end of a set period in time.",
"title": "Professional certificates awarded by tertiary education providers"
},
{
"paragraph_id": 15,
"text": "There are many professional bodies for accountants and auditors throughout the world; some of them are legally recognized in their jurisdictions. Public accountants are the accountancy and control experts that are legally certified in different jurisdictions to work in public practices, certifying accounts as statutory auditors, eventually selling advice and services to other individuals and businesses. Today, however, many work within private corporations, financial industry, and government bodies.",
"title": "Areas of certification"
},
{
"paragraph_id": 16,
"text": "Cf. Accountancy qualifications and regulation",
"title": "Areas of certification"
},
{
"paragraph_id": 17,
"text": "Aviators are certified through theoretical and in-flight examinations. Requirements for certifications are quite equal in most countries and are regulated by each National Aviation Authority. The existing certificates or pilot licenses are:",
"title": "Areas of certification"
},
{
"paragraph_id": 18,
"text": "Licensing in these categories require not only examinations but also a minimum number of flight hours. All categories are available for Fixed-Wing Aircraft (airplanes) and Rotatory-Wing Aircraft (helicopters). Within each category, aviators may also obtain certifications in:",
"title": "Areas of certification"
},
{
"paragraph_id": 19,
"text": "Usually, aviators must be certified also in their log books for the type and model of aircraft they are allowed to fly. Currency checks as well as regular medical check-ups with a frequency of 6 months, 12 months, or 36 months, depending on the type of flying permitted, are obligatory. An aviator can fly only if holding:",
"title": "Areas of certification"
},
{
"paragraph_id": 20,
"text": "In Europe, the ANSP, ATCO & ANSP technicians are certified according to EUROCONTROL Safety Regulatory Requirement (ESARRs) (according to EU regulation 2096/2005 \"Common Requirements\").",
"title": "Areas of certification"
},
{
"paragraph_id": 21,
"text": "In the United States, several communications certifications are conferred by the Electronics Technicians Association.",
"title": "Areas of certification"
},
{
"paragraph_id": 22,
"text": "Certification is often used in the professions of software engineering and information technology.",
"title": "Areas of certification"
},
{
"paragraph_id": 23,
"text": "Conferred by the International Dance Council CID at UNESCO, the International Certification of Dance Studies is awarded to students who have completed 150 hours of classes in a specific form of dance for Level 1. Another 150 hours are required for Level 2 and so on till Level 10. This is the only international certification for dance since the International Dance Council CID is the official body for all forms of dance; it is usually given in addition to local or national certificates, that is why it is colloquially called \"the dancer's passport\". Students cannot apply for this certification directly – they have to ask their school to apply on their behalf. This certification is awarded free of charge, there is no cost other than membership fees.",
"title": "Areas of certification"
},
{
"paragraph_id": 24,
"text": "International Dance Council CID at UNESCO administers the International Certification of Dance Studies.",
"title": "Areas of certification"
},
{
"paragraph_id": 25,
"text": "In the United States, several electronics certifications are provided by the Electronics Technicians Association.",
"title": "Areas of certification"
},
{
"paragraph_id": 26,
"text": "The Federal Emergency Management Agency's EMI offers credentials and training opportunities for United States citizens. Students do not have to be employed by FEMA or be federal employees for some of the programs.",
"title": "Areas of certification"
},
{
"paragraph_id": 27,
"text": "Professional engineering is any act of planning, designing, composing, measuring, evaluating, inspecting, advising, reporting, directing or supervising, or managing any of the foregoing, that requires the application of engineering principles and that concerns the safeguarding of life, health, property, economic interests, the public interest or the environment.",
"title": "Areas of certification"
},
{
"paragraph_id": 28,
"text": "Event planning includes budgeting, scheduling, site selection, acquiring necessary permits, coordinating transportation and parking, arranging for speakers or entertainers, arranging decor, event security, catering, coordinating with third-party vendors, and emergency plans.",
"title": "Areas of certification"
},
{
"paragraph_id": 29,
"text": "Common event planning certifications include:",
"title": "Areas of certification"
},
{
"paragraph_id": 30,
"text": "Facility management can be defined as an aspect of engineering management science that deals with the planning, designing, coordination of space and maintenance of a built environment to enhance quality service management system. Service Quality System includes activities like security, maintenance, catering, and external as well as internal cleaning. In general, it is also the coordination and harmonization of various specialist disciplines to create the best possible working environment for staff.",
"title": "Areas of certification"
},
{
"paragraph_id": 31,
"text": "Facility management is an interdisciplinary field devoted to the coordination of space, infrastructure, people and organization, often associated with the administration of office blocks, arenas, schools, convention centers, shopping complexes, hospitals, hotels, etc. However, FM facilitates on a wider range of activities than just business services and these are referred to as non-core functions.",
"title": "Areas of certification"
},
{
"paragraph_id": 32,
"text": "A warehouse management system (WMS) is a part of the supply chain and primarily aims to control the movement and storage of materials within a warehouse and process the associated transactions, including shipping, receiving, putaway and picking. The systems also direct and optimize stock putaway based on real-time information about the status of bin utilization. A WMS monitors the progress of products through the warehouse. It involves the physical warehouse infrastructure, tracking systems, and communication between product stations.",
"title": "Areas of certification"
},
{
"paragraph_id": 33,
"text": "More precisely, warehouse management involves the receipt, storage and movement of goods, (normally finished goods), to intermediate storage locations or to a final customer. In the multi-echelon model for distribution, there may be multiple levels of warehouses. This includes a central warehouse, a regional warehouses (serviced by the central warehouse) and potentially retail warehouses (serviced by the regional warehouses).",
"title": "Areas of certification"
},
{
"paragraph_id": 34,
"text": "IECEx covers the specialized field of explosion protection associated with the use of equipment in areas where flammable gases, liquids and combustible dusts may be present. This system provides the assurance that equipment is manufactured to meet safety standards, and that services such as installation, repair and overhaul also comply with IEC International Standards on 60079 series. The UNECE (United Nations Economic Commission for Europe), cited IECEx as one example of a practice model for the verification of conformity to IEC Standards, for European smaller countries with no certification schemes for such equipment. It published a \"Common Regulatory Framework\" as a suggestion for those countries implementing a certification program for the explosive atmospheres' segment.",
"title": "Areas of certification"
},
{
"paragraph_id": 35,
"text": "In the United States, insurance professionals are licensed separately by each state. Many individuals seek one or more certifications to distinguish themselves from their peers.",
"title": "Areas of certification"
},
{
"paragraph_id": 36,
"text": "TESOL is a large field of employment with widely varying degrees of regulation. Most provision worldwide is through the state school system of each individual country, and as such, the instructors tend to be trained primary- or secondary school teachers who are native speakers of the language of their pupils, and not of English. Though native speakers of English have been working in non-English speaking countries in this capacity for years, it was not until the last twenty-five years or so that there was any widespread focus on training particularly for this field. Previously, workers in this sort of job were people engaging in backpacker tourism hoping to earn some extra travel money or well-educated professionals in other fields volunteering, or retired people. These sort of people are certainly still to be found, but there are many who consider TESOL their main profession.",
"title": "Areas of certification"
},
{
"paragraph_id": 37,
"text": "One of the problems facing these full-time teachers is the absence of an international governing body for the certification or licensure of English language teachers. However, Cambridge University and its subsidiary body UCLES are pioneers in trying to get some degree of accountability and quality control to consumers of English courses, through their CELTA and DELTA programs. Trinity College London has equivalent programs, the CertTESOL and the LTCL DipTESOL. They offer initial certificates in teaching, in which candidates are trained in language awareness and classroom techniques, and given a chance to practice teaching, after which feedback is reported. Both institutions have as a follow-up a professional diploma, usually taken after a year or two in the field. Although the initial certificate is available to anyone with a high school education, the diploma is meant to be a post-graduate qualification and can in fact be incorporated into a master's degree program.",
"title": "Areas of certification"
},
{
"paragraph_id": 38,
"text": "An increasing number of attorneys are choosing to be recognized as having special expertise in certain fields of law. According to the American Bar Association, a lawyer who is a certified specialist has been recognized by an independent professional certifying organization as having an enhanced level of skill and expertise, as well as substantial involvement in an established legal specialty. These organizations require a lawyer to demonstrate special training, experience and knowledge to ensure that the lawyer's recognition is meaningful and reliable. Lawyer conduct with regard to specialty certification is regulated by the states.",
"title": "Areas of certification"
},
{
"paragraph_id": 39,
"text": "Legal administrators vary in their day-to-day responsibilities and job requirements. The Association of Legal Administrators (ALA) is the credentialing body of the Certified Legal Manager (CLM) certification program. CLMs are recognized as administrators who have passed a comprehensive examination and have met other eligibility requirements.:",
"title": "Areas of certification"
},
{
"paragraph_id": 40,
"text": "In Australia, ALIA (Australian Library and Information Association) certifies librarians and library technicians. Distinguished librarians who have completed a high level of professional learning are awarded the Distinguished Certified Professional Award. Prior to 2013, this award was known as Associate Fellows.",
"title": "Areas of certification"
},
{
"paragraph_id": 41,
"text": "In New Zealand, the accrediting body is LIANZA (Library and Information Association of New Zealand Aotearoa Te Rau Herenga O Aotearoa). LIANZA accredit prominent librarians at three levels, Fellows, Life Members and Associates.",
"title": "Areas of certification"
},
{
"paragraph_id": 42,
"text": "Logistician is the profession in the logistics and transport sectors, including sea, air, land and rail modes. Professional qualification for logisticians usually carries post-nominal letters.",
"title": "Areas of certification"
},
{
"paragraph_id": 43,
"text": "Certification granting bodies include, but are not limited to, Institute for Supply Management (ISM), Association for Operations Management (APICS), Chartered Institute of Logistics and Transport (CILT), International Society of Logistics (SOLE), Canadian Institute of Traffic and Transportation (CITT), and Allied Council for Commerce and Logistics (ACCL).",
"title": "Areas of certification"
},
{
"paragraph_id": 44,
"text": "Management consulting is the practice of providing consulting services to organizations to improve their performance or in any way to assist in achieving any sort of organizational objectives.",
"title": "Areas of certification"
},
{
"paragraph_id": 45,
"text": "The profession's primary certification is the \"Certified Management Consultant\" (CMC) designation.",
"title": "Areas of certification"
},
{
"paragraph_id": 46,
"text": "Certification granting bodies are the approximately 50 Institutes of Management Consulting belonging to the International Council of Management Consulting Institutes (ICMCI).",
"title": "Areas of certification"
},
{
"paragraph_id": 47,
"text": "Churches have their own process of who may use various religious titles. Protestant churches typically require a Masters of Divinity, accreditation by the denomination and ordination by the local church in order for a minister to become a \"Reverend\". Those qualifications may or may not also give government authorization to solemnize marriages.",
"title": "Areas of certification"
},
{
"paragraph_id": 48,
"text": "Board certification is the process by which a physician in the United States documents by written, practical or computer based testing, illustrating a mastery of knowledge and skills that define a particular area of medical specialization. The American Board of Medical Specialties, a not-for-profit organization, assists 24 approved medical specialty boards in the development and use of standards in the ongoing evaluation and certification of physicians.",
"title": "Areas of certification"
},
{
"paragraph_id": 49,
"text": "Medical specialty certification in the United States is a voluntary process. While medical licensure sets the minimum competency requirements to diagnose and treat patients, it is not specialty specific. Board certification demonstrates a physician's exceptional expertise in a particular specialty or sub-specialty of medical practice.",
"title": "Areas of certification"
},
{
"paragraph_id": 50,
"text": "Patients, physicians, health care providers, insurers and quality organizations regard certification as an important measure of a physician's knowledge, experience and skills to provide quality health care within a given specialty.",
"title": "Areas of certification"
},
{
"paragraph_id": 51,
"text": "Other professional certifications include certifications such as medical licenses, Membership of the Royal College of Physicians, Fellowship of the Royal College of Physicians and Surgeons of Canada, nursing board certification, diplomas in social work. The Commission for Certification in Geriatric Pharmacy certifies pharmacists that are knowledgeable about principles of geriatric pharmacotherapy and the provision of pharmaceutical care to the elderly. Additional certifying bodies relating to the medical field include:",
"title": "Areas of certification"
},
{
"paragraph_id": 52,
"text": "NCPRP stands for \"National Certified Peer Recovery Professional\", and the NCPRP credential and exam were developed in collaboration with the International Certification Board of Recovery Professionals (ICBRP) and is currently being administered by PARfessionals.",
"title": "Areas of certification"
},
{
"paragraph_id": 53,
"text": "PARfessionals is a professional organization and all of the available courses are professional development and pre-certification courses.",
"title": "Areas of certification"
},
{
"paragraph_id": 54,
"text": "The NCPRP credential and exam focus primarily on the concept of peer recovery through mental health and addiction recovery. It has the main purpose of training student-candidates on how to become peer recovery professionals who can provide guidance, knowledge or assistance for individuals who have had similar experiences.",
"title": "Areas of certification"
},
{
"paragraph_id": 55,
"text": "Each student-candidate must complete several key steps which include initial registration; the pre-certification review course; and all applicable sections of the official application in order to become eligible to complete the final step, which is the NCPRP certification exam.",
"title": "Areas of certification"
},
{
"paragraph_id": 56,
"text": "The NCPRP credential is obtained once a participant successfully passes the NCPRP certification exam by the second attempt and is valid for five years.",
"title": "Areas of certification"
},
{
"paragraph_id": 57,
"text": "Organizations that offer various certifications include:",
"title": "Areas of certification"
},
{
"paragraph_id": 58,
"text": "National Board of Public Health Examiners, www.nbphe.org",
"title": "Areas of certification"
},
{
"paragraph_id": 59,
"text": "In the US, the Universal Accreditation Board, an organization composed of the Public Relations Society of America, the Agricultural Relations Council, the National School Public Relations Association, the Religious Communicators Council and other public relations professional societies, administers the Accreditation in Public Relations (APR), a voluntary certification program for public relations practitioners.",
"title": "Areas of certification"
},
{
"paragraph_id": 60,
"text": "The Certified Public Participation Professional (CP3) and Master Certified Public Participation Professional (MCP3) are awarded by two regions of the International Association for Public Participation (IAP2) Archived 17 August 2019 at the Wayback Machine: IAP2 Canada and IAP2 USA. As of 2019, only 25 individuals had achieved either of these distinctions. The CP3 designation is awarded upon successfully completing a three-step process that includes a written application documenting the individual's experience in the profession, a written response to a case study, and an in-person oral assessment.",
"title": "Areas of certification"
},
{
"paragraph_id": 61,
"text": "Individuals seeking certification are assessed against 5 Core Competencies, which are the essential capabilities for a professional in this field to effectively design, implement, and evaluate public participation programs. The competencies emerged from qualitative analysis of a comprehensive list of knowledge, attitudes, beliefs, skills, behaviors, and capabilities identified in June 2014 by more than 100 P2 professionals from around the world. The descriptions and quality standards for each competency were developed, tested, and refined through an iterative process involving IAP2 members. Each competency is further divided into individual criteria. An individual must meet or exceed every criterion to achieve the CP3 designation. IAP2 USA's program includes 29 criteria. IAP2 Canada's program includes 31 criteria; the two additional criteria in Canada address federal requirements for indigenous engagement. The MCP3 designation recognizes additional specialization and expertise and is assessed through a written application available only to individuals who have already achieved the CP3 designation.",
"title": "Areas of certification"
},
{
"paragraph_id": 62,
"text": "To maintain professional certification, individuals must maintain active membership in IAP2, provide a minimum of 20 hours (annually) of volunteer (unpaid) service to IAP2, and participate in a minimum of 12 hours (annually) of continued professional development.",
"title": "Areas of certification"
},
{
"paragraph_id": 63,
"text": "The Building Owners and Managers Association and the International Facility Management Association offer professional certifications for the operation and management of commercial properties.",
"title": "Areas of certification"
},
{
"paragraph_id": 64,
"text": "Organizations offering certification include:",
"title": "Areas of certification"
},
{
"paragraph_id": 65,
"text": "Conferred by the National Speakers Association, the Certified Speaking Professional (CSP) is the speaking profession's international measure of professional platform competence. This certification is awarded by the National Speakers Association. Only about 10% of the speakers who belong to the Global Speakers Federation (GSF) hold this designation. Those who have earned their certification have done so by demonstrating a track record of experience and expertise.",
"title": "Areas of certification"
},
{
"paragraph_id": 66,
"text": "Political commentators have criticized professional or occupational licensing, especially medical and legal licensing, for restricting the supply of services and therefore making them more expensive, often putting them out of reach of the poor.",
"title": "Criticisms"
},
{
"paragraph_id": 67,
"text": "The proliferation of IT certifications (both offered and attained) has led some technologists to question their value. Proprietary content that has been distributed on the Internet allows some to gain credentials without the implied depth or breadth of expertise.",
"title": "Criticisms"
}
] | Professional certification, trade certification, or professional designation, often called simply certification or qualification, is a designation earned by a person to assure qualification to perform a job or task. Not all certifications that use post-nominal letters are an acknowledgement of educational achievement, or an agency appointed to safeguard the public interest. | 2001-09-03T19:59:42Z | 2023-12-19T14:04:17Z | [
"Template:Multiple issues",
"Template:Use dmy dates",
"Template:See also",
"Template:Main",
"Template:Cite book",
"Template:Citation needed",
"Template:According to whom",
"Template:Webarchive",
"Template:ISBN",
"Template:Short description",
"Template:Reflist",
"Template:Dead link",
"Template:Unreferenced section",
"Template:Cite web",
"Template:Cite news"
] | https://en.wikipedia.org/wiki/Professional_certification |
6,255 | Carl Menger | Carl Menger von Wolfensgrün (/ˈmɛŋɡər/; German: [ˈmɛŋɐ]; 28 February 1840 – 26 February 1921) was an Austrian economist and the founder of the Austrian School of economics. Menger contributed to the development of the theories of marginalism and marginal utility, which rejected cost-of-production theory of value, such as developed by the classical economists such as Adam Smith and David Ricardo. As a departure from such, he would go on to call his resultant perspective, the subjective theory of value.
Carl Menger von Wolfensgrün was born in the city of Neu-Sandez in Galicia, Austrian Empire, which is now Nowy Sącz in Poland. He was the son of a wealthy family of minor nobility; his father, Anton Menger, was a lawyer. His mother, Caroline Gerżabek, was the daughter of a wealthy Bohemian merchant. He had two brothers, Anton and Max, both prominent as lawyers. His son, Karl Menger, was a mathematician who taught for many years at Illinois Institute of Technology.
After attending gymnasium he studied law at the Universities of Prague and Vienna and later received a doctorate in jurisprudence from the Jagiellonian University in Kraków. In the 1860s Menger left school and enjoyed a stint as a journalist reporting and analyzing market news, first at the Lemberger Zeitung in Lemberg, Austrian Galicia (now Lviv, Ukraine) and later at the Wiener Zeitung in Vienna.
During the course of his newspaper work, he noticed a discrepancy between what the classical economics he was taught in school said about price determination and what real world market participants believed. In 1867 Menger began a study of political economy which culminated in 1871 with the publication of his Principles of Economics (Grundsätze der Volkswirtschaftslehre), thus becoming the father of the Austrian School of economic thought. It was in this work that he challenged classical cost-based theories of value with his theory of marginality – that price is determined at the margin.
In 1872 Menger was enrolled into the law faculty at the University of Vienna and spent the next several years teaching finance and political economy both in seminars and lectures to a growing number of students. In 1873, he received the university's chair of economic theory at the very young age of 33.
In 1876 Menger began tutoring Archduke Rudolf von Habsburg, the Crown Prince of Austria in political economy and statistics. For two years, Menger accompanied the prince during his travels, first through continental Europe and then later through the British Isles. He is also thought to have assisted the crown prince in the composition of a pamphlet, published anonymously in 1878, which was highly critical of the higher Austrian aristocracy. His association with the prince would last until Rudolf's suicide in 1889.
In 1878 Rudolf's father, Emperor Franz Joseph, appointed Menger to the chair of political economy at Vienna. The title of Hofrat was conferred on him, and he was appointed to the Austrian Herrenhaus in 1900.
Ensconced in his professorship, he set about refining and defending the positions he took and methods he utilized in Principles, the result of which was the 1883 publication of Investigations into the Method of the Social Sciences with Special Reference to Economics (Untersuchungen über die Methode der Socialwissenschaften und der politischen Oekonomie insbesondere). The book caused a firestorm of debate, during which members of the historical school of economics began to derisively call Menger and his students the "Austrian School" to emphasize their departure from mainstream German economic thought – the term was specifically used in an unfavorable review by Gustav von Schmoller.
In 1884 Menger responded with the pamphlet The Errors of Historicism in German Economics and launched the infamous Methodenstreit, or methodological debate, between the Historical School and the Austrian School. During this time Menger began to attract like-minded disciples who would go on to make their own mark on the field of economics, most notably Eugen von Böhm-Bawerk, and Friedrich von Wieser.
In the late 1880s, Menger was appointed to head a commission to reform the Austrian monetary system. Over the course of the next decade, he authored a plethora of articles which would revolutionize monetary theory, including "The Theory of Capital" (1888) and "Money" (1892). Largely due to his pessimism about the state of German scholarship, Menger resigned his professorship in 1903 to concentrate on study.
There are different opinions on Menger's philosophical influences. But it is without discussion that there is a rudimentary dispute of Menger with Plato and a very meticulous one with Aristotle, especially with his ethics.
"Plato holds that money is an agreed sign for change and Aristotle says, that money came into being as an agreement, not by nature, but by law."
Also, the influence of Kant is provable. Many authors emphasize also rationalism and idealism, as is represented by Christian Wolff. Looking at the literature, most writers think that Menger represents an essential Aristotelian position. This is surprisingly a position that is contrary to his theory of the subjective value and his individualistic methodological position.
Another entry is the use of deduction or induction. With his price theory can be shown that Menger is nominalistic and, stronger, anti-essentialistic. That is to say that his approach is inductionalistic.
Menger used his subjective theory of value to arrive at what he considered one of the most powerful insights in economics: "both sides gain from exchange". Unlike William Jevons, Menger did not believe that goods provide "utils," or units of utility. Rather, he wrote, goods are valuable because they serve various uses whose importance differs. Menger also came up with an explanation of how money develops that is still accepted by some schools of thought today.
Menger believed that gold and silver were the precious metals that were adopted as money for their unique attributes like costliness, durability, and easy preservation, making them the "most popular vehicle for hoarding as well as the goods most highly favoured in commerce." Menger showed that "their special saleableness" tended to make their bid-ask spread tighter than any other market good, which led to their adoption as a general medium of exchange and evolution in many societies as money. | [
{
"paragraph_id": 0,
"text": "Carl Menger von Wolfensgrün (/ˈmɛŋɡər/; German: [ˈmɛŋɐ]; 28 February 1840 – 26 February 1921) was an Austrian economist and the founder of the Austrian School of economics. Menger contributed to the development of the theories of marginalism and marginal utility, which rejected cost-of-production theory of value, such as developed by the classical economists such as Adam Smith and David Ricardo. As a departure from such, he would go on to call his resultant perspective, the subjective theory of value.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Carl Menger von Wolfensgrün was born in the city of Neu-Sandez in Galicia, Austrian Empire, which is now Nowy Sącz in Poland. He was the son of a wealthy family of minor nobility; his father, Anton Menger, was a lawyer. His mother, Caroline Gerżabek, was the daughter of a wealthy Bohemian merchant. He had two brothers, Anton and Max, both prominent as lawyers. His son, Karl Menger, was a mathematician who taught for many years at Illinois Institute of Technology.",
"title": "Biography"
},
{
"paragraph_id": 2,
"text": "After attending gymnasium he studied law at the Universities of Prague and Vienna and later received a doctorate in jurisprudence from the Jagiellonian University in Kraków. In the 1860s Menger left school and enjoyed a stint as a journalist reporting and analyzing market news, first at the Lemberger Zeitung in Lemberg, Austrian Galicia (now Lviv, Ukraine) and later at the Wiener Zeitung in Vienna.",
"title": "Biography"
},
{
"paragraph_id": 3,
"text": "During the course of his newspaper work, he noticed a discrepancy between what the classical economics he was taught in school said about price determination and what real world market participants believed. In 1867 Menger began a study of political economy which culminated in 1871 with the publication of his Principles of Economics (Grundsätze der Volkswirtschaftslehre), thus becoming the father of the Austrian School of economic thought. It was in this work that he challenged classical cost-based theories of value with his theory of marginality – that price is determined at the margin.",
"title": "Biography"
},
{
"paragraph_id": 4,
"text": "In 1872 Menger was enrolled into the law faculty at the University of Vienna and spent the next several years teaching finance and political economy both in seminars and lectures to a growing number of students. In 1873, he received the university's chair of economic theory at the very young age of 33.",
"title": "Biography"
},
{
"paragraph_id": 5,
"text": "In 1876 Menger began tutoring Archduke Rudolf von Habsburg, the Crown Prince of Austria in political economy and statistics. For two years, Menger accompanied the prince during his travels, first through continental Europe and then later through the British Isles. He is also thought to have assisted the crown prince in the composition of a pamphlet, published anonymously in 1878, which was highly critical of the higher Austrian aristocracy. His association with the prince would last until Rudolf's suicide in 1889.",
"title": "Biography"
},
{
"paragraph_id": 6,
"text": "In 1878 Rudolf's father, Emperor Franz Joseph, appointed Menger to the chair of political economy at Vienna. The title of Hofrat was conferred on him, and he was appointed to the Austrian Herrenhaus in 1900.",
"title": "Biography"
},
{
"paragraph_id": 7,
"text": "Ensconced in his professorship, he set about refining and defending the positions he took and methods he utilized in Principles, the result of which was the 1883 publication of Investigations into the Method of the Social Sciences with Special Reference to Economics (Untersuchungen über die Methode der Socialwissenschaften und der politischen Oekonomie insbesondere). The book caused a firestorm of debate, during which members of the historical school of economics began to derisively call Menger and his students the \"Austrian School\" to emphasize their departure from mainstream German economic thought – the term was specifically used in an unfavorable review by Gustav von Schmoller.",
"title": "Biography"
},
{
"paragraph_id": 8,
"text": "In 1884 Menger responded with the pamphlet The Errors of Historicism in German Economics and launched the infamous Methodenstreit, or methodological debate, between the Historical School and the Austrian School. During this time Menger began to attract like-minded disciples who would go on to make their own mark on the field of economics, most notably Eugen von Böhm-Bawerk, and Friedrich von Wieser.",
"title": "Biography"
},
{
"paragraph_id": 9,
"text": "In the late 1880s, Menger was appointed to head a commission to reform the Austrian monetary system. Over the course of the next decade, he authored a plethora of articles which would revolutionize monetary theory, including \"The Theory of Capital\" (1888) and \"Money\" (1892). Largely due to his pessimism about the state of German scholarship, Menger resigned his professorship in 1903 to concentrate on study.",
"title": "Biography"
},
{
"paragraph_id": 10,
"text": "There are different opinions on Menger's philosophical influences. But it is without discussion that there is a rudimentary dispute of Menger with Plato and a very meticulous one with Aristotle, especially with his ethics.",
"title": "Philosophical influences"
},
{
"paragraph_id": 11,
"text": "\"Plato holds that money is an agreed sign for change and Aristotle says, that money came into being as an agreement, not by nature, but by law.\"",
"title": "Philosophical influences"
},
{
"paragraph_id": 12,
"text": "Also, the influence of Kant is provable. Many authors emphasize also rationalism and idealism, as is represented by Christian Wolff. Looking at the literature, most writers think that Menger represents an essential Aristotelian position. This is surprisingly a position that is contrary to his theory of the subjective value and his individualistic methodological position.",
"title": "Philosophical influences"
},
{
"paragraph_id": 13,
"text": "Another entry is the use of deduction or induction. With his price theory can be shown that Menger is nominalistic and, stronger, anti-essentialistic. That is to say that his approach is inductionalistic.",
"title": "Philosophical influences"
},
{
"paragraph_id": 14,
"text": "Menger used his subjective theory of value to arrive at what he considered one of the most powerful insights in economics: \"both sides gain from exchange\". Unlike William Jevons, Menger did not believe that goods provide \"utils,\" or units of utility. Rather, he wrote, goods are valuable because they serve various uses whose importance differs. Menger also came up with an explanation of how money develops that is still accepted by some schools of thought today.",
"title": "Economics"
},
{
"paragraph_id": 15,
"text": "Menger believed that gold and silver were the precious metals that were adopted as money for their unique attributes like costliness, durability, and easy preservation, making them the \"most popular vehicle for hoarding as well as the goods most highly favoured in commerce.\" Menger showed that \"their special saleableness\" tended to make their bid-ask spread tighter than any other market good, which led to their adoption as a general medium of exchange and evolution in many societies as money.",
"title": "Economics"
}
] | Carl Menger von Wolfensgrün was an Austrian economist and the founder of the Austrian School of economics. Menger contributed to the development of the theories of marginalism and marginal utility, which rejected cost-of-production theory of value, such as developed by the classical economists such as Adam Smith and David Ricardo. As a departure from such, he would go on to call his resultant perspective, the subjective theory of value. | 2002-02-25T15:51:15Z | 2023-12-10T20:17:56Z | [
"Template:Cite encyclopedia",
"Template:Internet Archive author",
"Template:Austrian economists",
"Template:Blacklisted-links",
"Template:Infobox economist",
"Template:Cite book",
"Template:Cite journal",
"Template:Reflist",
"Template:Austrian School sidebar",
"Template:IPAc-en",
"Template:Cite news",
"Template:Webarchive",
"Template:Authority control",
"Template:About",
"Template:IPA-de",
"Template:Lang",
"Template:Commons category",
"Template:NIE Poster",
"Template:Portal bar",
"Template:Short description",
"Template:Expand German",
"Template:Essay-like",
"Template:Cite web",
"Template:Wikiquote"
] | https://en.wikipedia.org/wiki/Carl_Menger |
6,256 | List of cartoonists | This is a list of cartoonists, visual artists who specialize in drawing cartoons. This list includes only notable cartoonists and is not meant to be exhaustive. | [
{
"paragraph_id": 0,
"text": "This is a list of cartoonists, visual artists who specialize in drawing cartoons. This list includes only notable cartoonists and is not meant to be exhaustive.",
"title": ""
}
] | This is a list of cartoonists, visual artists who specialize in drawing cartoons. This list includes only notable cartoonists and is not meant to be exhaustive. | 2001-09-13T01:51:36Z | 2023-12-14T12:32:54Z | [
"Template:Cite book",
"Template:Short description",
"Template:Div col",
"Template:Div col end",
"Template:Portal",
"Template:Reflist"
] | https://en.wikipedia.org/wiki/List_of_cartoonists |
6,258 | Civilization | A civilization (British English: civilisation) is any complex society characterized by the development of the state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system).
Civilizations are often characterized by additional features as well, including agriculture, architecture, infrastructure, technological advancement, a currency, taxation, regulation, and specialization of labour.
Historically, a civilization has often been understood as a larger and "more advanced" culture, in implied contrast to smaller, supposedly less advanced cultures. In this broad sense, a civilization contrasts with non-centralized tribal societies, including the cultures of nomadic pastoralists, Neolithic societies, or hunter-gatherers; however, sometimes it also contrasts with the cultures found within civilizations themselves. Civilizations are organized densely-populated settlements divided into hierarchical social classes with a ruling elite and subordinate urban and rural populations, which engage in intensive agriculture, mining, small-scale manufacture and trade. Civilization concentrates power, extending human control over the rest of nature, including over other human beings.
The word civilization relates to the Latin civitas or 'city'. As the National Geographic Society has explained it: "This is why the most basic definition of the word civilization is 'a society made up of cities.'" The earliest emergence of civilizations is generally connected with the final stages of the Neolithic Revolution in West Asia, culminating in the relatively rapid process of urban revolution and state formation, a political development associated with the appearance of a governing elite.
The English word civilization comes from the 16th-century French civilisé ('civilized'), from Latin: civilis ('civil'), related to civis ('citizen') and civitas ('city'). The fundamental treatise is Norbert Elias's The Civilizing Process (1939), which traces social mores from medieval courtly society to the early modern period. In The Philosophy of Civilization (1923), Albert Schweitzer outlines two opinions: one purely material and the other material and ethical. He said that the world crisis was from humanity losing the ethical idea of civilization, "the sum total of all progress made by man in every sphere of action and from every point of view in so far as the progress helps towards the spiritual perfecting of individuals as the progress of all progress".
Related words like "civility" developed in the mid-16th century. The abstract noun "civilization", meaning "civilized condition", came in the 1760s, again from French. The first known use in French is in 1757, by Victor de Riqueti, marquis de Mirabeau, and the first use in English is attributed to Adam Ferguson, who in his 1767 Essay on the History of Civil Society wrote, "Not only the individual advances from infancy to manhood but the species itself from rudeness to civilisation". The word was therefore opposed to barbarism or rudeness, in the active pursuit of progress characteristic of the Age of Enlightenment.
In the late 1700s and early 1800s, during the French Revolution, "civilization" was used in the singular, never in the plural, and meant the progress of humanity as a whole. This is still the case in French. The use of "civilizations" as a countable noun was in occasional use in the 19th century, but has become much more common in the later 20th century, sometimes just meaning culture (itself in origin an uncountable noun, made countable in the context of ethnography). Only in this generalized sense does it become possible to speak of a "medieval civilization", which in Elias's sense would have been an oxymoron. Using the terms "civilization" and "culture" as equivalents are controversial and generally rejected so that for example some types of culture are not normally described as civilizations.
Already in the 18th century, civilization was not always seen as an improvement. One historically important distinction between culture and civilization is from the writings of Rousseau, particularly his work about education, Emile. Here, civilization, being more rational and socially driven, is not fully in accord with human nature, and "human wholeness is achievable only through the recovery of or approximation to an original discursive or prerational natural unity" (see noble savage). From this, a new approach was developed, especially in Germany, first by Johann Gottfried Herder and later by philosophers such as Kierkegaard and Nietzsche. This sees cultures as natural organisms, not defined by "conscious, rational, deliberative acts", but a kind of pre-rational "folk spirit". Civilization, in contrast, though more rational and more successful in material progress, is unnatural and leads to "vices of social life" such as guile, hypocrisy, envy and avarice. In World War II, Leo Strauss, having fled Germany, argued in New York that this opinion of civilization was behind Nazism and German militarism and nihilism.
Social scientists such as V. Gordon Childe have named a number of traits that distinguish a civilization from other kinds of society. Civilizations have been distinguished by their means of subsistence, types of livelihood, settlement patterns, forms of government, social stratification, economic systems, literacy and other cultural traits. Andrew Nikiforuk argues that "civilizations relied on shackled human muscle. It took the energy of slaves to plant crops, clothe emperors, and build cities" and considers slavery to be a common feature of pre-modern civilizations.
All civilizations have depended on agriculture for subsistence, with the possible exception of some early civilizations in Peru which may have depended upon maritime resources.
The traditional "surplus model" postulates that cereal farming results in accumulated storage and a surplus of food, particularly when people use intensive agricultural techniques such as artificial fertilization, irrigation and crop rotation. It is possible but more difficult to accumulate horticultural production, and so civilizations based on horticultural gardening have been very rare. Grain surpluses have been especially important because grain can be stored for a long time.
Research from the Journal of Political Economy contradicts the surplus model. It postulates that horticultural gardening was more productive than cereal farming. However, only cereal farming produced civilization because of the appropriability of yearly harvest. Rural populations that could only grow cereals could be taxed allowing for a taxing elite and urban development. This also had a negative effect on rural population, increasing relative agricultural output per farmer. Farming efficiency created food surplus and sustained the food surplus through decreasing rural population growth in favour of urban growth. Suitability of highly productive roots and tubers was in fact a curse of plenty, which prevented the emergence of states and impeded economic development.
A surplus of food permits some people to do things besides producing food for a living: early civilizations included soldiers, artisans, priests and priestesses, and other people with specialized careers. A surplus of food results in a division of labour and a more diverse range of human activity, a defining trait of civilizations. However, in some places hunter-gatherers have had access to food surpluses, such as among some of the indigenous peoples of the Pacific Northwest and perhaps during the Mesolithic Natufian culture. It is possible that food surpluses and relatively large scale social organization and division of labour predates plant and animal domestication.
Civilizations have distinctly different settlement patterns from other societies. The word civilization is sometimes defined as "living in cities". Non-farmers tend to gather in cities to work and to trade.
Compared with other societies, civilizations have a more complex political structure, namely the state. State societies are more stratified than other societies; there is a greater difference among the social classes. The ruling class, normally concentrated in the cities, has control over much of the surplus and exercises its will through the actions of a government or bureaucracy. Morton Fried, a conflict theorist and Elman Service, an integration theorist, have classified human cultures based on political systems and social inequality. This system of classification contains four categories.
Economically, civilizations display more complex patterns of ownership and exchange than less organized societies. Living in one place allows people to accumulate more personal possessions than nomadic people. Some people also acquire landed property, or private ownership of the land. Because a percentage of people in civilizations do not grow their own food, they must trade their goods and services for food in a market system, or receive food through the levy of tribute, redistributive taxation, tariffs or tithes from the food producing segment of the population. Early human cultures functioned through a gift economy supplemented by limited barter systems. By the early Iron Age, contemporary civilizations developed money as a medium of exchange for increasingly complex transactions. In a village, the potter makes a pot for the brewer and the brewer compensates the potter by giving him a certain amount of beer. In a city, the potter may need a new roof, the roofer may need new shoes, the cobbler may need new horseshoes, the blacksmith may need a new coat and the tanner may need a new pot. These people may not be personally acquainted with one another and their needs may not occur all at the same time. A monetary system is a way of organizing these obligations to ensure that they are fulfilled. From the days of the earliest monetarized civilizations, monopolistic controls of monetary systems have benefited the social and political elites.
The transition from simpler to more complex economies does not necessarily mean an improvement in the living standards of the populace. For example, although the Middle Ages is often portrayed as an era of decline from the Roman Empire, studies have shown that the average stature of males in the Middle Ages (c. 500 to 1500 CE) was greater than it was for males during the preceding Roman Empire and the succeeding Early Modern Period (c. 1500 to 1800 CE). Also, the Plains Indians of North America in the 19th century were taller than their "civilized" American and European counterparts. The average stature of a population is a good measurement of the adequacy of its access to necessities, especially food, and its freedom from disease.
Writing, developed first by people in Sumer, is considered a hallmark of civilization and "appears to accompany the rise of complex administrative bureaucracies or the conquest state". Traders and bureaucrats relied on writing to keep accurate records. Like money, the writing was necessitated by the size of the population of a city and the complexity of its commerce among people who are not all personally acquainted with each other. However, writing is not always necessary for civilization, as shown by the Inca civilization of the Andes, which did not use writing at all but except for a complex recording system consisting of knotted strings of different lengths and colors: the "Quipus", and still functioned as a civilized society.
Aided by their division of labour and central government planning, civilizations have developed many other diverse cultural traits. These include organized religion, development in the arts, and countless new advances in science and technology.
Assessments of what level of civilization a polity has reached are based on comparisons of the relative importance of agricultural as opposed to trading or manufacturing capacities, the territorial extensions of its power, the complexity of its division of labour, and the carrying capacity of its urban centres. Secondary elements include a developed transportation system, writing, standardized measurement, currency, contractual and tort-based legal systems, art, architecture, mathematics, scientific understanding, metallurgy, political structures, and organized religion.
The idea of civilization implies a progression or development from a previous "uncivilized" state. Traditionally, cultures that defined themselves as "civilized" often did so in contrast to other societies or human groupings viewed as less civilized, calling the latter barbarians, savages, and primitives. Indeed, the modern Western idea of civilization developed as a contrast to the indigenous cultures European settlers encountered the European colonization of the Americas and Australia. The term "primitive," though once used in anthropology, has now been largely condemned by anthropologists because of its derogatory connotations and because it implies that the cultures it refers to are relics of a past time that do not change or progress.
Because of this, societies regarding themselves as "civilized" have sometimes sought to dominate and assimilate "uncivilized" cultures into a "civilized" way of living. In the nineteenth century, the idea of European culture as "civilized" and superior to "uncivilized" non-European cultures was fully developed, and civilization became a core part of European identity. The idea of civilization can also be used as a justification for dominating another culture and dispossessing a people of their land. For example, in Australia, British settlers justified the displacement of indigenous Australians by observing that the land appeared uncultivated and wild, which to them reflected that the inhabitants were not civilized enough to "improve" it. The behaviors and modes of subsistence that characterize civilization have been spread by colonization, invasion, religious conversion, the extension of bureaucratic control and trade, and by the introduction of new technologies to cultures that did not previously have them. Though aspects of culture associated with civilization can be freely adopted through contact between cultures, since early modern times Eurocentric ideals of "civilization" have been widely imposed upon cultures through coercion and dominance. These ideals complemented a philosophy that assumed there were innate differences between "civilized" and "uncivilized" peoples.
"Civilization" can also refer to the culture of a complex society, not just the society itself. Every society, civilization or not, has a specific set of ideas and customs, and a certain set of manufactures and arts that make it unique. Civilizations tend to develop intricate cultures, including a state-based decision-making apparatus, a literature, professional art, architecture, organized religion and complex customs of education, coercion and control associated with maintaining the elite.
The intricate culture associated with civilization has a tendency to spread to and influence other cultures, sometimes assimilating them into the civilization, a classic example being Chinese civilization and its influence on nearby civilizations such as Korea, Japan and Vietnam Many civilizations are actually large cultural spheres containing many nations and regions. The civilization in which someone lives is that person's broadest cultural identity.
It is precisely the protection of this cultural identity that is becoming increasingly important nationally and internationally. According to international law, the United Nations and UNESCO try to set up and enforce relevant rules. The aim is to preserve the cultural heritage of humanity and also the cultural identity, especially in the case of war and armed conflict. According to Karl von Habsburg, President of Blue Shield International, the destruction of cultural assets is also part of psychological warfare. The target of the attack is often the opponent's cultural identity, which is why symbolic cultural assets become a main target. It is also intended to destroy the particularly sensitive cultural memory (museums, archives, monuments, etc.), the grown cultural diversity, and the economic basis (such as tourism) of a state, region or community.
Many historians have focused on these broad cultural spheres and have treated civilizations as discrete units. Early twentieth-century philosopher Oswald Spengler, uses the German word Kultur, "culture", for what many call a "civilization". Spengler believed a civilization's coherence is based on a single primary cultural symbol. Cultures experience cycles of birth, life, decline, and death, often supplanted by a potent new culture, formed around a compelling new cultural symbol. Spengler states civilization is the beginning of the decline of a culture as "the most external and artificial states of which a species of developed humanity is capable".
This "unified culture" concept of civilization also influenced the theories of historian Arnold J. Toynbee in the mid-twentieth century. Toynbee explored civilization processes in his multi-volume A Study of History, which traced the rise and, in most cases, the decline of 21 civilizations and five "arrested civilizations". Civilizations generally declined and fell, according to Toynbee, because of the failure of a "creative minority", through moral or religious decline, to meet some important challenge, rather than mere economic or environmental causes.
Samuel P. Huntington defines civilization as "the highest cultural grouping of people and the broadest level of cultural identity people have short of that which distinguishes humans from other species".
Another group of theorists, making use of systems theory, looks at a civilization as a complex system, i.e., a framework by which a group of objects can be analysed that work in concert to produce some result. Civilizations can be seen as networks of cities that emerge from pre-urban cultures and are defined by the economic, political, military, diplomatic, social and cultural interactions among them. Any organization is a complex social system and a civilization is a large organization. Systems theory helps guard against superficial and misleading analogies in the study and description of civilizations.
Systems theorists look at many types of relations between cities, including economic relations, cultural exchanges and political/diplomatic/military relations. These spheres often occur on different scales. For example, trade networks were, until the nineteenth century, much larger than either cultural spheres or political spheres. Extensive trade routes, including the Silk Road through Central Asia and Indian Ocean sea routes linking the Roman Empire, Persian Empire, India and China, were well established 2000 years ago when these civilizations scarcely shared any political, diplomatic, military, or cultural relations. The first evidence of such long-distance trade is in the ancient world. During the Uruk period, Guillermo Algaze has argued that trade relations connected Egypt, Mesopotamia, Iran and Afghanistan. Resin found later in the Royal Cemetery at Ur is suggested was traded northwards from Mozambique.
Many theorists argue that the entire world has already become integrated into a single "world system", a process known as globalization. Different civilizations and societies all over the globe are economically, politically, and even culturally interdependent in many ways. There is debate over when this integration began, and what sort of integration – cultural, technological, economic, political, or military-diplomatic – is the key indicator in determining the extent of a civilization. David Wilkinson has proposed that economic and military-diplomatic integration of the Mesopotamian and Egyptian civilizations resulted in the creation of what he calls the "Central Civilization" around 1500 BCE. Central Civilization later expanded to include the entire Middle East and Europe, and then expanded to a global scale with European colonization, integrating the Americas, Australia, China and Japan by the nineteenth century. According to Wilkinson, civilizations can be culturally heterogeneous, like the Central Civilization, or homogeneous, like the Japanese civilization. What Huntington calls the "clash of civilizations" might be characterized by Wilkinson as a clash of cultural spheres within a single global civilization. Others point to the Crusading movement as the first step in globalization. The more conventional viewpoint is that networks of societies have expanded and shrunk since ancient times, and that the current globalized economy and culture is a product of recent European colonialism.
The notion of human history as a succession of "civilizations" is an entirely modern one. In the European Age of Discovery, emerging Modernity was put into stark contrast with the Neolithic and Mesolithic stage of the cultures of many of the peoples they encountered.Nonetheless, developments in the Neolithic stage, such as agriculture and sedentary settlement, were critical to the development of modern conceptions of civilization.
The Natufian culture in the Levantine corridor provides the earliest case of a Neolithic Revolution, with the planting of cereal crops attested from c. 11,000 BCE. The earliest neolithic technology and lifestyle were established first in Western Asia (for example at Göbekli Tepe, from about 9,130 BCE), later in the Yellow River and Yangtze basins in China (for example the Peiligang and Pengtoushan cultures), and from these cores spread across Eurasia. Mesopotamia is the site of the earliest civilizations developing from 7,400 years ago. This area has been evaluated by Beverley Milton-Edwards as having "inspired some of the most important developments in human history including the invention of the wheel, the building of the earliest cities and the development of written cursive script".
Similar pre-civilized "neolithic revolutions" also began independently from 7,000 BCE in northwestern South America (the Caral-Supe civilization) and in Mesoamerica. The Black Sea area served as a cradle of European civilization. The site of Solnitsata – a prehistoric fortified (walled) stone settlement (prehistoric city) (5500–4200 BCE) – is believed by some archeologists to be the oldest known town in present-day Europe.
The 8.2 Kiloyear Arid Event and the 5.9 Kiloyear Interpluvial saw the drying out of semiarid regions and a major spread of deserts. This climate change shifted the cost-benefit ratio of endemic violence between communities, which saw the abandonment of unwalled village communities and the appearance of walled cities, seen by some as a characteristic of early civilizations.
This "urban revolution" –a term introduced by Childe in the 1930s– from the 4th millennium BCE, marked the beginning of the accumulation of transferable economic surpluses, which helped economies and cities develop. Urban revolutions were associated with the state monopoly of violence, the appearance of a warrior, or soldier, class and endemic warfare (a state of continual or frequent warfare), the rapid development of hierarchies, and the use of human sacrifice.
The civilized urban revolution in turn was dependent upon the development of sedentism, the domestication of grains, plants and animals, the permanence of settlements and development of lifestyles that facilitated economies of scale and accumulation of surplus production by particular social sectors. The transition from complex cultures to civilizations, while still disputed, seems to be associated with the development of state structures, in which power was further monopolized by an élite ruling class who practiced human sacrifice.
Towards the end of the Neolithic period, various elitist Chalcolithic civilizations began to rise in various "cradles" from around 3600 BCE beginning with Mesopotamia, expanding into large-scale kingdoms and empires in the course of the Bronze Age (Akkadian Empire, Indus Valley Civilization, Old Kingdom of Egypt, Neo-Sumerian Empire, Middle Assyrian Empire, Babylonian Empire, Hittite Empire, and to some degree the territorial expansions of the Elamites, Hurrians, Amorites and Ebla).
Outside the Old World, a later development took place independently in the Pre-Columbian Americas. Urbanization in the Norte Chico civilization in coastal Peru emerged about 3200 BCE; the oldest known Mayan city, located in Guatemala, dates to about 750 BCE. and Teotihuacan in Mexico was one of the largest cities in the world in 350 CE, with a population of about 125,000.
The Bronze Age collapse was followed by the Iron Age around 1200 BCE, during which a number of new civilizations emerged, culminating in a period from the 8th to the 3rd century BCE which Karl Jaspers termed the Axial Age, presented as a critical transitional phase leading to classical civilization.
A major technological and cultural transition to modernity began approximately 1500 CE in Western Europe, and from this beginning new approaches to science and law spread rapidly around the world, incorporating earlier cultures into the technological and industrial society of the present.
Civilizations are traditionally understood as ending in one of two ways; either through incorporation into another expanding civilization (e.g. as Ancient Egypt was incorporated into Hellenistic Greek, and subsequently Roman civilizations), or by collapsing and reverting to a simpler form of living, as happens in so-called Dark Ages.
There have been many explanations put forward for the collapse of civilization. Some focus on historical examples, and others on general theory.
According to political scientist Samuel P. Huntington, the 21st century will be characterized by a clash of civilizations, which he believes will replace the conflicts between nation-states and ideologies that were prominent in the 19th and 20th centuries. However, this viewpoint been strongly challenged by others such as Edward Said, Muhammed Asadi and Amartya Sen. Ronald Inglehart and Pippa Norris have argued that the "true clash of civilizations" between the Muslim world and the West is caused by the Muslim rejection of the West's more liberal sexual values, rather than a difference in political ideology, although they note that this lack of tolerance is likely to lead to an eventual rejection of (true) democracy. In Identity and Violence Sen questions if people should be divided along the lines of a supposed "civilization", defined by religion and culture only. He argues that this ignores the many others identities that make up people and leads to a focus on differences.
Cultural Historian Morris Berman argues in Dark Ages America: the End of Empire that in the corporate consumerist United States, the very factors that once propelled it to greatness―extreme individualism, territorial and economic expansion, and the pursuit of material wealth―have pushed the United States across a critical threshold where collapse is inevitable. Politically associated with over-reach, and as a result of the environmental exhaustion and polarization of wealth between rich and poor, he concludes the current system is fast arriving at a situation where continuation of the existing system saddled with huge deficits and a hollowed-out economy is physically, socially, economically and politically impossible. Although developed in much more depth, Berman's thesis is similar in some ways to that of Urban Planner, Jane Jacobs who argues that the five pillars of United States culture are in serious decay: community and family; higher education; the effective practice of science; taxation and government; and the self-regulation of the learned professions. The corrosion of these pillars, Jacobs argues, is linked to societal ills such as environmental crisis, racism and the growing gulf between rich and poor.
Cultural critic and author Derrick Jensen argues that modern civilization is directed towards the domination of the environment and humanity itself in an intrinsically harmful, unsustainable, and self-destructive fashion. Defending his definition both linguistically and historically, he defines civilization as "a culture... that both leads to and emerges from the growth of cities", with "cities" defined as "people living more or less permanently in one place in densities high enough to require the routine importation of food and other necessities of life". This need for civilizations to import ever more resources, he argues, stems from their over-exploitation and diminution of their own local resources. Therefore, civilizations inherently adopt imperialist and expansionist policies and, to maintain these, highly militarized, hierarchically structured, and coercion-based cultures and lifestyles.
The Kardashev scale classifies civilizations based on their level of technological advancement, specifically measured by the amount of energy a civilization is able to harness. The scale is only hypothetical, but it puts energy consumption in a cosmic perspective. The Kardashev scale makes provisions for civilizations far more technologically advanced than any currently known to exist.
The current scientific consensus is that human beings are the only animal species with the cognitive ability to create civilizations that has emerged on Earth. A recent thought experiment, the silurian hypothesis, however, considers whether it would "be possible to detect an industrial civilization in the geological record" given the paucity of geological information about eras before the quaternary.
Astronomers speculate about the existence of communicating intelligent civilizations within and beyond the Milky Way galaxy, usually using variants of the Drake equation. They also conduct searches for such intelligences – such as for technological traces, called "technosignatures". The proposed proto-scientific field "xenoarchaeology" is concerned with the study of artifact remains of non-human civilizations to reconstruct and interpret past lives of alien societies if such get discovered and confirmed scientifically. | [
{
"paragraph_id": 0,
"text": "A civilization (British English: civilisation) is any complex society characterized by the development of the state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system).",
"title": ""
},
{
"paragraph_id": 1,
"text": "Civilizations are often characterized by additional features as well, including agriculture, architecture, infrastructure, technological advancement, a currency, taxation, regulation, and specialization of labour.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Historically, a civilization has often been understood as a larger and \"more advanced\" culture, in implied contrast to smaller, supposedly less advanced cultures. In this broad sense, a civilization contrasts with non-centralized tribal societies, including the cultures of nomadic pastoralists, Neolithic societies, or hunter-gatherers; however, sometimes it also contrasts with the cultures found within civilizations themselves. Civilizations are organized densely-populated settlements divided into hierarchical social classes with a ruling elite and subordinate urban and rural populations, which engage in intensive agriculture, mining, small-scale manufacture and trade. Civilization concentrates power, extending human control over the rest of nature, including over other human beings.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The word civilization relates to the Latin civitas or 'city'. As the National Geographic Society has explained it: \"This is why the most basic definition of the word civilization is 'a society made up of cities.'\" The earliest emergence of civilizations is generally connected with the final stages of the Neolithic Revolution in West Asia, culminating in the relatively rapid process of urban revolution and state formation, a political development associated with the appearance of a governing elite.",
"title": ""
},
{
"paragraph_id": 4,
"text": "The English word civilization comes from the 16th-century French civilisé ('civilized'), from Latin: civilis ('civil'), related to civis ('citizen') and civitas ('city'). The fundamental treatise is Norbert Elias's The Civilizing Process (1939), which traces social mores from medieval courtly society to the early modern period. In The Philosophy of Civilization (1923), Albert Schweitzer outlines two opinions: one purely material and the other material and ethical. He said that the world crisis was from humanity losing the ethical idea of civilization, \"the sum total of all progress made by man in every sphere of action and from every point of view in so far as the progress helps towards the spiritual perfecting of individuals as the progress of all progress\".",
"title": "History of the concept"
},
{
"paragraph_id": 5,
"text": "Related words like \"civility\" developed in the mid-16th century. The abstract noun \"civilization\", meaning \"civilized condition\", came in the 1760s, again from French. The first known use in French is in 1757, by Victor de Riqueti, marquis de Mirabeau, and the first use in English is attributed to Adam Ferguson, who in his 1767 Essay on the History of Civil Society wrote, \"Not only the individual advances from infancy to manhood but the species itself from rudeness to civilisation\". The word was therefore opposed to barbarism or rudeness, in the active pursuit of progress characteristic of the Age of Enlightenment.",
"title": "History of the concept"
},
{
"paragraph_id": 6,
"text": "In the late 1700s and early 1800s, during the French Revolution, \"civilization\" was used in the singular, never in the plural, and meant the progress of humanity as a whole. This is still the case in French. The use of \"civilizations\" as a countable noun was in occasional use in the 19th century, but has become much more common in the later 20th century, sometimes just meaning culture (itself in origin an uncountable noun, made countable in the context of ethnography). Only in this generalized sense does it become possible to speak of a \"medieval civilization\", which in Elias's sense would have been an oxymoron. Using the terms \"civilization\" and \"culture\" as equivalents are controversial and generally rejected so that for example some types of culture are not normally described as civilizations.",
"title": "History of the concept"
},
{
"paragraph_id": 7,
"text": "Already in the 18th century, civilization was not always seen as an improvement. One historically important distinction between culture and civilization is from the writings of Rousseau, particularly his work about education, Emile. Here, civilization, being more rational and socially driven, is not fully in accord with human nature, and \"human wholeness is achievable only through the recovery of or approximation to an original discursive or prerational natural unity\" (see noble savage). From this, a new approach was developed, especially in Germany, first by Johann Gottfried Herder and later by philosophers such as Kierkegaard and Nietzsche. This sees cultures as natural organisms, not defined by \"conscious, rational, deliberative acts\", but a kind of pre-rational \"folk spirit\". Civilization, in contrast, though more rational and more successful in material progress, is unnatural and leads to \"vices of social life\" such as guile, hypocrisy, envy and avarice. In World War II, Leo Strauss, having fled Germany, argued in New York that this opinion of civilization was behind Nazism and German militarism and nihilism.",
"title": "History of the concept"
},
{
"paragraph_id": 8,
"text": "Social scientists such as V. Gordon Childe have named a number of traits that distinguish a civilization from other kinds of society. Civilizations have been distinguished by their means of subsistence, types of livelihood, settlement patterns, forms of government, social stratification, economic systems, literacy and other cultural traits. Andrew Nikiforuk argues that \"civilizations relied on shackled human muscle. It took the energy of slaves to plant crops, clothe emperors, and build cities\" and considers slavery to be a common feature of pre-modern civilizations.",
"title": "Characteristics"
},
{
"paragraph_id": 9,
"text": "All civilizations have depended on agriculture for subsistence, with the possible exception of some early civilizations in Peru which may have depended upon maritime resources.",
"title": "Characteristics"
},
{
"paragraph_id": 10,
"text": "The traditional \"surplus model\" postulates that cereal farming results in accumulated storage and a surplus of food, particularly when people use intensive agricultural techniques such as artificial fertilization, irrigation and crop rotation. It is possible but more difficult to accumulate horticultural production, and so civilizations based on horticultural gardening have been very rare. Grain surpluses have been especially important because grain can be stored for a long time.",
"title": "Characteristics"
},
{
"paragraph_id": 11,
"text": "Research from the Journal of Political Economy contradicts the surplus model. It postulates that horticultural gardening was more productive than cereal farming. However, only cereal farming produced civilization because of the appropriability of yearly harvest. Rural populations that could only grow cereals could be taxed allowing for a taxing elite and urban development. This also had a negative effect on rural population, increasing relative agricultural output per farmer. Farming efficiency created food surplus and sustained the food surplus through decreasing rural population growth in favour of urban growth. Suitability of highly productive roots and tubers was in fact a curse of plenty, which prevented the emergence of states and impeded economic development.",
"title": "Characteristics"
},
{
"paragraph_id": 12,
"text": "A surplus of food permits some people to do things besides producing food for a living: early civilizations included soldiers, artisans, priests and priestesses, and other people with specialized careers. A surplus of food results in a division of labour and a more diverse range of human activity, a defining trait of civilizations. However, in some places hunter-gatherers have had access to food surpluses, such as among some of the indigenous peoples of the Pacific Northwest and perhaps during the Mesolithic Natufian culture. It is possible that food surpluses and relatively large scale social organization and division of labour predates plant and animal domestication.",
"title": "Characteristics"
},
{
"paragraph_id": 13,
"text": "Civilizations have distinctly different settlement patterns from other societies. The word civilization is sometimes defined as \"living in cities\". Non-farmers tend to gather in cities to work and to trade.",
"title": "Characteristics"
},
{
"paragraph_id": 14,
"text": "Compared with other societies, civilizations have a more complex political structure, namely the state. State societies are more stratified than other societies; there is a greater difference among the social classes. The ruling class, normally concentrated in the cities, has control over much of the surplus and exercises its will through the actions of a government or bureaucracy. Morton Fried, a conflict theorist and Elman Service, an integration theorist, have classified human cultures based on political systems and social inequality. This system of classification contains four categories.",
"title": "Characteristics"
},
{
"paragraph_id": 15,
"text": "Economically, civilizations display more complex patterns of ownership and exchange than less organized societies. Living in one place allows people to accumulate more personal possessions than nomadic people. Some people also acquire landed property, or private ownership of the land. Because a percentage of people in civilizations do not grow their own food, they must trade their goods and services for food in a market system, or receive food through the levy of tribute, redistributive taxation, tariffs or tithes from the food producing segment of the population. Early human cultures functioned through a gift economy supplemented by limited barter systems. By the early Iron Age, contemporary civilizations developed money as a medium of exchange for increasingly complex transactions. In a village, the potter makes a pot for the brewer and the brewer compensates the potter by giving him a certain amount of beer. In a city, the potter may need a new roof, the roofer may need new shoes, the cobbler may need new horseshoes, the blacksmith may need a new coat and the tanner may need a new pot. These people may not be personally acquainted with one another and their needs may not occur all at the same time. A monetary system is a way of organizing these obligations to ensure that they are fulfilled. From the days of the earliest monetarized civilizations, monopolistic controls of monetary systems have benefited the social and political elites.",
"title": "Characteristics"
},
{
"paragraph_id": 16,
"text": "The transition from simpler to more complex economies does not necessarily mean an improvement in the living standards of the populace. For example, although the Middle Ages is often portrayed as an era of decline from the Roman Empire, studies have shown that the average stature of males in the Middle Ages (c. 500 to 1500 CE) was greater than it was for males during the preceding Roman Empire and the succeeding Early Modern Period (c. 1500 to 1800 CE). Also, the Plains Indians of North America in the 19th century were taller than their \"civilized\" American and European counterparts. The average stature of a population is a good measurement of the adequacy of its access to necessities, especially food, and its freedom from disease.",
"title": "Characteristics"
},
{
"paragraph_id": 17,
"text": "Writing, developed first by people in Sumer, is considered a hallmark of civilization and \"appears to accompany the rise of complex administrative bureaucracies or the conquest state\". Traders and bureaucrats relied on writing to keep accurate records. Like money, the writing was necessitated by the size of the population of a city and the complexity of its commerce among people who are not all personally acquainted with each other. However, writing is not always necessary for civilization, as shown by the Inca civilization of the Andes, which did not use writing at all but except for a complex recording system consisting of knotted strings of different lengths and colors: the \"Quipus\", and still functioned as a civilized society.",
"title": "Characteristics"
},
{
"paragraph_id": 18,
"text": "Aided by their division of labour and central government planning, civilizations have developed many other diverse cultural traits. These include organized religion, development in the arts, and countless new advances in science and technology.",
"title": "Characteristics"
},
{
"paragraph_id": 19,
"text": "Assessments of what level of civilization a polity has reached are based on comparisons of the relative importance of agricultural as opposed to trading or manufacturing capacities, the territorial extensions of its power, the complexity of its division of labour, and the carrying capacity of its urban centres. Secondary elements include a developed transportation system, writing, standardized measurement, currency, contractual and tort-based legal systems, art, architecture, mathematics, scientific understanding, metallurgy, political structures, and organized religion.",
"title": "Characteristics"
},
{
"paragraph_id": 20,
"text": "The idea of civilization implies a progression or development from a previous \"uncivilized\" state. Traditionally, cultures that defined themselves as \"civilized\" often did so in contrast to other societies or human groupings viewed as less civilized, calling the latter barbarians, savages, and primitives. Indeed, the modern Western idea of civilization developed as a contrast to the indigenous cultures European settlers encountered the European colonization of the Americas and Australia. The term \"primitive,\" though once used in anthropology, has now been largely condemned by anthropologists because of its derogatory connotations and because it implies that the cultures it refers to are relics of a past time that do not change or progress.",
"title": "Characteristics"
},
{
"paragraph_id": 21,
"text": "Because of this, societies regarding themselves as \"civilized\" have sometimes sought to dominate and assimilate \"uncivilized\" cultures into a \"civilized\" way of living. In the nineteenth century, the idea of European culture as \"civilized\" and superior to \"uncivilized\" non-European cultures was fully developed, and civilization became a core part of European identity. The idea of civilization can also be used as a justification for dominating another culture and dispossessing a people of their land. For example, in Australia, British settlers justified the displacement of indigenous Australians by observing that the land appeared uncultivated and wild, which to them reflected that the inhabitants were not civilized enough to \"improve\" it. The behaviors and modes of subsistence that characterize civilization have been spread by colonization, invasion, religious conversion, the extension of bureaucratic control and trade, and by the introduction of new technologies to cultures that did not previously have them. Though aspects of culture associated with civilization can be freely adopted through contact between cultures, since early modern times Eurocentric ideals of \"civilization\" have been widely imposed upon cultures through coercion and dominance. These ideals complemented a philosophy that assumed there were innate differences between \"civilized\" and \"uncivilized\" peoples.",
"title": "Characteristics"
},
{
"paragraph_id": 22,
"text": "\"Civilization\" can also refer to the culture of a complex society, not just the society itself. Every society, civilization or not, has a specific set of ideas and customs, and a certain set of manufactures and arts that make it unique. Civilizations tend to develop intricate cultures, including a state-based decision-making apparatus, a literature, professional art, architecture, organized religion and complex customs of education, coercion and control associated with maintaining the elite.",
"title": "Cultural identity"
},
{
"paragraph_id": 23,
"text": "The intricate culture associated with civilization has a tendency to spread to and influence other cultures, sometimes assimilating them into the civilization, a classic example being Chinese civilization and its influence on nearby civilizations such as Korea, Japan and Vietnam Many civilizations are actually large cultural spheres containing many nations and regions. The civilization in which someone lives is that person's broadest cultural identity.",
"title": "Cultural identity"
},
{
"paragraph_id": 24,
"text": "It is precisely the protection of this cultural identity that is becoming increasingly important nationally and internationally. According to international law, the United Nations and UNESCO try to set up and enforce relevant rules. The aim is to preserve the cultural heritage of humanity and also the cultural identity, especially in the case of war and armed conflict. According to Karl von Habsburg, President of Blue Shield International, the destruction of cultural assets is also part of psychological warfare. The target of the attack is often the opponent's cultural identity, which is why symbolic cultural assets become a main target. It is also intended to destroy the particularly sensitive cultural memory (museums, archives, monuments, etc.), the grown cultural diversity, and the economic basis (such as tourism) of a state, region or community.",
"title": "Cultural identity"
},
{
"paragraph_id": 25,
"text": "Many historians have focused on these broad cultural spheres and have treated civilizations as discrete units. Early twentieth-century philosopher Oswald Spengler, uses the German word Kultur, \"culture\", for what many call a \"civilization\". Spengler believed a civilization's coherence is based on a single primary cultural symbol. Cultures experience cycles of birth, life, decline, and death, often supplanted by a potent new culture, formed around a compelling new cultural symbol. Spengler states civilization is the beginning of the decline of a culture as \"the most external and artificial states of which a species of developed humanity is capable\".",
"title": "Cultural identity"
},
{
"paragraph_id": 26,
"text": "This \"unified culture\" concept of civilization also influenced the theories of historian Arnold J. Toynbee in the mid-twentieth century. Toynbee explored civilization processes in his multi-volume A Study of History, which traced the rise and, in most cases, the decline of 21 civilizations and five \"arrested civilizations\". Civilizations generally declined and fell, according to Toynbee, because of the failure of a \"creative minority\", through moral or religious decline, to meet some important challenge, rather than mere economic or environmental causes.",
"title": "Cultural identity"
},
{
"paragraph_id": 27,
"text": "Samuel P. Huntington defines civilization as \"the highest cultural grouping of people and the broadest level of cultural identity people have short of that which distinguishes humans from other species\".",
"title": "Cultural identity"
},
{
"paragraph_id": 28,
"text": "Another group of theorists, making use of systems theory, looks at a civilization as a complex system, i.e., a framework by which a group of objects can be analysed that work in concert to produce some result. Civilizations can be seen as networks of cities that emerge from pre-urban cultures and are defined by the economic, political, military, diplomatic, social and cultural interactions among them. Any organization is a complex social system and a civilization is a large organization. Systems theory helps guard against superficial and misleading analogies in the study and description of civilizations.",
"title": "Complex systems"
},
{
"paragraph_id": 29,
"text": "Systems theorists look at many types of relations between cities, including economic relations, cultural exchanges and political/diplomatic/military relations. These spheres often occur on different scales. For example, trade networks were, until the nineteenth century, much larger than either cultural spheres or political spheres. Extensive trade routes, including the Silk Road through Central Asia and Indian Ocean sea routes linking the Roman Empire, Persian Empire, India and China, were well established 2000 years ago when these civilizations scarcely shared any political, diplomatic, military, or cultural relations. The first evidence of such long-distance trade is in the ancient world. During the Uruk period, Guillermo Algaze has argued that trade relations connected Egypt, Mesopotamia, Iran and Afghanistan. Resin found later in the Royal Cemetery at Ur is suggested was traded northwards from Mozambique.",
"title": "Complex systems"
},
{
"paragraph_id": 30,
"text": "Many theorists argue that the entire world has already become integrated into a single \"world system\", a process known as globalization. Different civilizations and societies all over the globe are economically, politically, and even culturally interdependent in many ways. There is debate over when this integration began, and what sort of integration – cultural, technological, economic, political, or military-diplomatic – is the key indicator in determining the extent of a civilization. David Wilkinson has proposed that economic and military-diplomatic integration of the Mesopotamian and Egyptian civilizations resulted in the creation of what he calls the \"Central Civilization\" around 1500 BCE. Central Civilization later expanded to include the entire Middle East and Europe, and then expanded to a global scale with European colonization, integrating the Americas, Australia, China and Japan by the nineteenth century. According to Wilkinson, civilizations can be culturally heterogeneous, like the Central Civilization, or homogeneous, like the Japanese civilization. What Huntington calls the \"clash of civilizations\" might be characterized by Wilkinson as a clash of cultural spheres within a single global civilization. Others point to the Crusading movement as the first step in globalization. The more conventional viewpoint is that networks of societies have expanded and shrunk since ancient times, and that the current globalized economy and culture is a product of recent European colonialism.",
"title": "Complex systems"
},
{
"paragraph_id": 31,
"text": "The notion of human history as a succession of \"civilizations\" is an entirely modern one. In the European Age of Discovery, emerging Modernity was put into stark contrast with the Neolithic and Mesolithic stage of the cultures of many of the peoples they encountered.Nonetheless, developments in the Neolithic stage, such as agriculture and sedentary settlement, were critical to the development of modern conceptions of civilization.",
"title": "History"
},
{
"paragraph_id": 32,
"text": "The Natufian culture in the Levantine corridor provides the earliest case of a Neolithic Revolution, with the planting of cereal crops attested from c. 11,000 BCE. The earliest neolithic technology and lifestyle were established first in Western Asia (for example at Göbekli Tepe, from about 9,130 BCE), later in the Yellow River and Yangtze basins in China (for example the Peiligang and Pengtoushan cultures), and from these cores spread across Eurasia. Mesopotamia is the site of the earliest civilizations developing from 7,400 years ago. This area has been evaluated by Beverley Milton-Edwards as having \"inspired some of the most important developments in human history including the invention of the wheel, the building of the earliest cities and the development of written cursive script\".",
"title": "History"
},
{
"paragraph_id": 33,
"text": "Similar pre-civilized \"neolithic revolutions\" also began independently from 7,000 BCE in northwestern South America (the Caral-Supe civilization) and in Mesoamerica. The Black Sea area served as a cradle of European civilization. The site of Solnitsata – a prehistoric fortified (walled) stone settlement (prehistoric city) (5500–4200 BCE) – is believed by some archeologists to be the oldest known town in present-day Europe.",
"title": "History"
},
{
"paragraph_id": 34,
"text": "The 8.2 Kiloyear Arid Event and the 5.9 Kiloyear Interpluvial saw the drying out of semiarid regions and a major spread of deserts. This climate change shifted the cost-benefit ratio of endemic violence between communities, which saw the abandonment of unwalled village communities and the appearance of walled cities, seen by some as a characteristic of early civilizations.",
"title": "History"
},
{
"paragraph_id": 35,
"text": "This \"urban revolution\" –a term introduced by Childe in the 1930s– from the 4th millennium BCE, marked the beginning of the accumulation of transferable economic surpluses, which helped economies and cities develop. Urban revolutions were associated with the state monopoly of violence, the appearance of a warrior, or soldier, class and endemic warfare (a state of continual or frequent warfare), the rapid development of hierarchies, and the use of human sacrifice.",
"title": "History"
},
{
"paragraph_id": 36,
"text": "The civilized urban revolution in turn was dependent upon the development of sedentism, the domestication of grains, plants and animals, the permanence of settlements and development of lifestyles that facilitated economies of scale and accumulation of surplus production by particular social sectors. The transition from complex cultures to civilizations, while still disputed, seems to be associated with the development of state structures, in which power was further monopolized by an élite ruling class who practiced human sacrifice.",
"title": "History"
},
{
"paragraph_id": 37,
"text": "Towards the end of the Neolithic period, various elitist Chalcolithic civilizations began to rise in various \"cradles\" from around 3600 BCE beginning with Mesopotamia, expanding into large-scale kingdoms and empires in the course of the Bronze Age (Akkadian Empire, Indus Valley Civilization, Old Kingdom of Egypt, Neo-Sumerian Empire, Middle Assyrian Empire, Babylonian Empire, Hittite Empire, and to some degree the territorial expansions of the Elamites, Hurrians, Amorites and Ebla).",
"title": "History"
},
{
"paragraph_id": 38,
"text": "Outside the Old World, a later development took place independently in the Pre-Columbian Americas. Urbanization in the Norte Chico civilization in coastal Peru emerged about 3200 BCE; the oldest known Mayan city, located in Guatemala, dates to about 750 BCE. and Teotihuacan in Mexico was one of the largest cities in the world in 350 CE, with a population of about 125,000.",
"title": "History"
},
{
"paragraph_id": 39,
"text": "The Bronze Age collapse was followed by the Iron Age around 1200 BCE, during which a number of new civilizations emerged, culminating in a period from the 8th to the 3rd century BCE which Karl Jaspers termed the Axial Age, presented as a critical transitional phase leading to classical civilization.",
"title": "History"
},
{
"paragraph_id": 40,
"text": "A major technological and cultural transition to modernity began approximately 1500 CE in Western Europe, and from this beginning new approaches to science and law spread rapidly around the world, incorporating earlier cultures into the technological and industrial society of the present.",
"title": "History"
},
{
"paragraph_id": 41,
"text": "Civilizations are traditionally understood as ending in one of two ways; either through incorporation into another expanding civilization (e.g. as Ancient Egypt was incorporated into Hellenistic Greek, and subsequently Roman civilizations), or by collapsing and reverting to a simpler form of living, as happens in so-called Dark Ages.",
"title": "Fall of civilizations"
},
{
"paragraph_id": 42,
"text": "There have been many explanations put forward for the collapse of civilization. Some focus on historical examples, and others on general theory.",
"title": "Fall of civilizations"
},
{
"paragraph_id": 43,
"text": "According to political scientist Samuel P. Huntington, the 21st century will be characterized by a clash of civilizations, which he believes will replace the conflicts between nation-states and ideologies that were prominent in the 19th and 20th centuries. However, this viewpoint been strongly challenged by others such as Edward Said, Muhammed Asadi and Amartya Sen. Ronald Inglehart and Pippa Norris have argued that the \"true clash of civilizations\" between the Muslim world and the West is caused by the Muslim rejection of the West's more liberal sexual values, rather than a difference in political ideology, although they note that this lack of tolerance is likely to lead to an eventual rejection of (true) democracy. In Identity and Violence Sen questions if people should be divided along the lines of a supposed \"civilization\", defined by religion and culture only. He argues that this ignores the many others identities that make up people and leads to a focus on differences.",
"title": "Future"
},
{
"paragraph_id": 44,
"text": "Cultural Historian Morris Berman argues in Dark Ages America: the End of Empire that in the corporate consumerist United States, the very factors that once propelled it to greatness―extreme individualism, territorial and economic expansion, and the pursuit of material wealth―have pushed the United States across a critical threshold where collapse is inevitable. Politically associated with over-reach, and as a result of the environmental exhaustion and polarization of wealth between rich and poor, he concludes the current system is fast arriving at a situation where continuation of the existing system saddled with huge deficits and a hollowed-out economy is physically, socially, economically and politically impossible. Although developed in much more depth, Berman's thesis is similar in some ways to that of Urban Planner, Jane Jacobs who argues that the five pillars of United States culture are in serious decay: community and family; higher education; the effective practice of science; taxation and government; and the self-regulation of the learned professions. The corrosion of these pillars, Jacobs argues, is linked to societal ills such as environmental crisis, racism and the growing gulf between rich and poor.",
"title": "Future"
},
{
"paragraph_id": 45,
"text": "Cultural critic and author Derrick Jensen argues that modern civilization is directed towards the domination of the environment and humanity itself in an intrinsically harmful, unsustainable, and self-destructive fashion. Defending his definition both linguistically and historically, he defines civilization as \"a culture... that both leads to and emerges from the growth of cities\", with \"cities\" defined as \"people living more or less permanently in one place in densities high enough to require the routine importation of food and other necessities of life\". This need for civilizations to import ever more resources, he argues, stems from their over-exploitation and diminution of their own local resources. Therefore, civilizations inherently adopt imperialist and expansionist policies and, to maintain these, highly militarized, hierarchically structured, and coercion-based cultures and lifestyles.",
"title": "Future"
},
{
"paragraph_id": 46,
"text": "The Kardashev scale classifies civilizations based on their level of technological advancement, specifically measured by the amount of energy a civilization is able to harness. The scale is only hypothetical, but it puts energy consumption in a cosmic perspective. The Kardashev scale makes provisions for civilizations far more technologically advanced than any currently known to exist.",
"title": "Future"
},
{
"paragraph_id": 47,
"text": "The current scientific consensus is that human beings are the only animal species with the cognitive ability to create civilizations that has emerged on Earth. A recent thought experiment, the silurian hypothesis, however, considers whether it would \"be possible to detect an industrial civilization in the geological record\" given the paucity of geological information about eras before the quaternary.",
"title": "Non-human civilizations"
},
{
"paragraph_id": 48,
"text": "Astronomers speculate about the existence of communicating intelligent civilizations within and beyond the Milky Way galaxy, usually using variants of the Drake equation. They also conduct searches for such intelligences – such as for technological traces, called \"technosignatures\". The proposed proto-scientific field \"xenoarchaeology\" is concerned with the study of artifact remains of non-human civilizations to reconstruct and interpret past lives of alien societies if such get discovered and confirmed scientifically.",
"title": "Non-human civilizations"
}
] | A civilization is any complex society characterized by the development of the state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language. Civilizations are often characterized by additional features as well, including agriculture, architecture, infrastructure, technological advancement, a currency, taxation, regulation, and specialization of labour. Historically, a civilization has often been understood as a larger and "more advanced" culture, in implied contrast to smaller, supposedly less advanced cultures. In this broad sense, a civilization contrasts with non-centralized tribal societies, including the cultures of nomadic pastoralists, Neolithic societies, or hunter-gatherers; however, sometimes it also contrasts with the cultures found within civilizations themselves. Civilizations are organized densely-populated settlements divided into hierarchical social classes with a ruling elite and subordinate urban and rural populations, which engage in intensive agriculture, mining, small-scale manufacture and trade. Civilization concentrates power, extending human control over the rest of nature, including over other human beings. The word civilization relates to the Latin civitas or 'city'. As the National Geographic Society has explained it: "This is why the most basic definition of the word civilization is 'a society made up of cities.'"
The earliest emergence of civilizations is generally connected with the final stages of the Neolithic Revolution in West Asia, culminating in the relatively rapid process of urban revolution and state formation, a political development associated with the appearance of a governing elite. | 2001-09-04T19:50:11Z | 2023-12-13T18:52:04Z | [
"Template:Short description",
"Template:Circa",
"Template:Notelist",
"Template:Cite encyclopaedia",
"Template:Webarchive",
"Template:ArXiv",
"Template:See also",
"Template:Obsolete source",
"Template:Multiref2",
"Template:Lang-la",
"Template:Efn",
"Template:Main",
"Template:Cite book",
"Template:Cite episode",
"Template:Refbegin",
"Template:ISSN",
"Template:Refend",
"Template:Use British English Oxford spelling",
"Template:Use dmy dates",
"Template:Further",
"Template:Columns-list",
"Template:Cite news",
"Template:ASIN",
"Template:Portal",
"Template:Cite web",
"Template:Cite thesis",
"Template:Wikiquote-inline",
"Template:Culture",
"Template:Cite magazine",
"Template:Wiktionary-inline",
"Template:Lang-en-GB",
"Template:Overref",
"Template:Lang",
"Template:Reflist",
"Template:Cite journal",
"Template:Bsn",
"Template:Authority control",
"Template:Other uses",
"Template:Citation needed",
"Template:Cite periodical",
"Template:ISBN",
"Template:Citation",
"Template:Cite Q"
] | https://en.wikipedia.org/wiki/Civilization |
6,259 | Civilization (video game) | Sid Meier's Civilization is a 1991 turn-based strategy 4X game developed and published by MicroProse. The game was originally developed for MS-DOS running on a PC, and it has undergone numerous revisions for various platforms. The player is tasked with leading an entire human civilization over the course of several millennia by controlling various areas such as urban development, exploration, government, trade, research, and military. The player can control individual units and advance the exploration, conquest and settlement of the game's world. The player can also make such decisions as setting forms of government, tax rates and research priorities. The player's civilization is in competition with other computer-controlled civilizations, with which the player can enter diplomatic relationships that can either end in alliances or lead to war.
Civilization was designed by Sid Meier and Bruce Shelley following the successes of Silent Service, Sid Meier's Pirates! and Railroad Tycoon. Civilization has sold 1.5 million copies since its release and is considered one of the most influential computer games in history due to its establishment of the 4X genre. In addition to its commercial and critical success, the game has been deemed pedagogically valuable due to its presentation of historical relationships. A multiplayer remake, Sid Meier's CivNet, was released for the PC in 1995. Civilization was followed by several sequels starting with Civilization II, with similar or modified scenarios.
Civilization is a turn-based single-player strategy game. The player takes on the role of the ruler of a civilization, starting with one (or occasionally two) settler units, and attempts to build an empire in competition with two to seven other civilizations. The game requires a fair amount of micromanagement (although less than other simulation games). Along with the larger tasks of exploration, warfare and diplomacy, the player has to make decisions about where to build new cities, which improvements or units to build in each city, which advances in knowledge should be sought (and at what rate), and how to transform the land surrounding the cities for maximum benefit. From time to time the player's towns may be harassed by barbarians, units with no specific nationality and no named leader. These threats only come from huts, unclaimed land or sea, so that over time and turns of exploration, there are fewer and fewer places from which barbarians will emanate.
Before the game begins, the player chooses which historical or current civilization to play. In contrast to later games in the Civilization series, this is largely a cosmetic choice, affecting titles, city names, musical heralds, and color. The choice does affect their starting position on the "Play on Earth" map, and thus different resources in one's initial cities, but has no effect on starting position when starting a random world game or a customized world game. The player's choice of civilization also prevents the computer from being able to play as that civilization or the other civilization of the same color, and since computer-controlled opponents display certain traits of their civilizations this affects gameplay as well. The Aztecs are both fiercely expansionist and generally extremely wealthy, for example. Other civilizations include the Americans, the Mongols, and Romans. Each civilization is led by a famous historical figure, such as Mahatma Gandhi for India.
The scope of Civilization is larger than most other games. The game begins in 4000 BC, before the Bronze Age, and can last through to AD 2100 (on the easiest setting) with Space Age and "future technologies". At the start of the game there are no cities anywhere in the world: the player controls one or two settler units, which can be used to found new cities in appropriate sites (and those cities may build other settler units, which can go out and found new cities, thus expanding the empire). Settlers can also alter terrain, build improvements such as mines and irrigation, build roads to connect cities, and later in the game they can construct railroads which offer unlimited movement.
As time advances, new technologies are developed; these technologies are the primary way in which the game changes and grows. At the start, players choose from advances such as pottery, the wheel, and the alphabet to, near the end of the game, nuclear fission and spaceflight. Players can gain a large advantage if their civilization is the first to learn a particular technology (the secrets of flight, for example) and put it to use in a military or other context. Most advances give access to new units, city improvements or derivative technologies: for example, the chariot unit becomes available after the wheel is developed, and the granary building becomes available to build after pottery is developed. The whole system of advancements from beginning to end is called the technology tree, or simply the Tech tree; this concept has been adopted in many other strategy games. Since only one tech may be "researched" at any given time, the order in which technologies are chosen makes a considerable difference in the outcome of the game and generally reflects the player's preferred style of gameplay.
Players can also build Wonders of the World in each of the epochs of the game, subject only to obtaining the prerequisite knowledge. These wonders are important achievements of society, science, culture and defense, ranging from the Pyramids and the Great Wall in the Ancient age, to Copernicus' Observatory and Magellan's Expedition in the middle period, up to the Apollo program, the United Nations, and the Manhattan Project in the modern era. Each wonder can only be built once in the world, and requires a lot of resources to build, far more than most other city buildings or units. Wonders provide unique benefits to the controlling civilization. For example, Magellan's Expedition increases the movement rate of naval units. Wonders typically affect either the city in which they are built (for example, the Colossus), every city on the continent (for example, J.S. Bach's Cathedral), or the civilization as a whole (for example, Darwin's Voyage). Some wonders are made obsolete by new technologies.
The game can be won by conquering all other civilizations or by winning the space race by reaching the star system of Alpha Centauri.
British designer Francis Tresham released his Civilization board game in 1980 under his company Hartland Trefoil. Avalon Hill had obtained the rights to publish it in the United States in 1981.
There were at least two attempts to make a computerized version of Tresham's game prior to 1990. Danielle Bunten Berry planned to start work on the game after completing M.U.L.E. in 1983, and again in 1985, after completing The Seven Cities of Gold at Electronic Arts. In 1983 Bunten and producer Joe Ybarra opted to first do Seven Cities of Gold. The success of Seven Cities in 1985 in turn led to a sequel, Heart of Africa. Bunten never returned to the idea of Civilization. Don Daglow, designer of Utopia, the first simulation game, began work programming a version of Civilization in 1987. He dropped the project, however, when he was offered an executive position at Brøderbund, and never returned to the game.
Sid Meier and Bill Stealey co-founded MicroProse in 1982 to develop flight simulators and other military strategy video games based on Stealey's past experiences as a United States Air Force pilot. Around 1989, Meier wanted to expand his repertoire beyond these types of games, as just having finished F-19 Stealth Fighter (1988, 1990), he said "Everything I thought was cool about a flight simulator had gone into that game." He took to heart the success of the new god game genre, in particular SimCity (1989) and Populous (1989). Specifically with SimCity, Meier recognized that video games could still be entertaining based on building something up. By then, Meier was not an official employee of MicroProse but worked under contract where the company paid him upfront for game development, a large payment on delivery of the game, and additional royalties on each game of his sold.
MicroProse had hired a number of Avalon Hill game designers, including Bruce Shelley. Among other works, Shelley had been responsible for adapting the railroad-based 1829 board game developed by Tresham into 1830: The Game of Railroads and Robber Barons. Shelley had joined MicroProse finding that the board game market was weakening in contrast to the video game market, and initially worked on F-19 Stealth Fighter. Meier recognized Shelley's abilities and background in game design and took him on as personal assistant designer to brainstorm new game ideas. The two initially worked on ideas for Covert Action, but had put these aside when they came up with the concepts for Railroad Tycoon (1990), based loosely on the 1829/1830 board games. Railroad Tycoon was generally well received at its release, but the title did not fit within the nature of flight simulators and military strategy from MicroProse's previous catalog. Meier and Shelley had started a sequel to Railroad Tycoon shortly after its release, but Stealey canceled the project.
One positive aspect both had taken from Railroad Tycoon was the idea of multiple smaller systems working together at the same time and the player having to manage them. Both Meier and Shelley recognized that the complex interactions between these systems led players to "make a lot of interesting decisions", and that ruling a whole civilization would readily work well with these underlying systems. Some time later, both discussed their love of the original Empire computer games, and Meier challenged Shelley to give him ten things he would change about Empire; Shelley provided him with twelve. Around May 1990, Meier presented Shelley with a 5-1/4" floppy disk which contained the first prototype of Civilization based on their past discussions and Shelley's list.
Meier described his development process as sculpting with clay. His prototype took elements from Empire, Railroad Tycoon, SimCity and the Civilization board game. This initial version of this game was a real-time simulation, with the player defining zones for their population to grow similar to zoning in SimCity. Meier and Shelley went back and forth with this, with Shelley providing suggestions based on his playthrough and acting as the game's producer, and Meier coding and reworking the game to address these points, and otherwise without involvement of other MicroProse staff. During this period, Stealey and the other managers became concerned that this game did not fit MicroProse's general catalog as strategy computer games had not yet proven successful. A few months into the development, Stealey requested them to put the project on hold and complete Covert Action, after which they could go back to their new game. Meier and Shelley completed Covert Action which was published in 1990.
Once Covert Action was released, Meier and Shelley returned to the prototype. The time away from the project allowed them to recognize that the real-time aspect was not working well, and reworked the game to become turn-based and dropped the zoning aspect, a change that Meier described as "like tossing the clay in the trash and getting a new lump". They incorporated elements of city management and military aspect from Empire, including creating individual military units as well as settler units that replaced the functionality of the zoning approach. Meier felt adding military and combat to the game was necessary: "The game really isn't about being civilized. The competition is what makes the game fun and the players play their best. At times, you have to make the player uncomfortable for the good of the player." Meier also opted to include a technology tree that would help to open the game to many more choices to the player as it continued, creating a non-linear experience. Meier felt players would be able to use the technology tree to adopt a style of play and from which they could use technologies to barter with the other opponents. While the game relies on established recorded history, Meier admitted he did not spend much time in research, usually only to assure the proper chronology or spellings; Shelley noted that they wanted to design for fun, not accuracy, and that "Everything we needed was pretty much available in the children’s section of the library."
Computer Gaming World reported in 1994 that "Sid Meier has stated on numerous occasions that he emphasizes the 'fun parts' of a simulation and throws out the rest". Meier described the process as "Add another bit [of clay]—no, that went too far. Scrape it off". He eliminated the potential for any civilization to fall on its own, believing this would be punishing to the player. "Though historically accurate", Meier said, "The moment the Krakatoa volcano blew up, or the bubonic plague came marching through, all anybody wanted to do was reload from a saved game". Meier omitted multiplayer alliances because the computer used them too effectively, causing players to think that it was cheating. He said that by contrast, minefields and minesweepers caused the computer to do "stupid things ... If you've got a feature that makes the AI look stupid, take it out. It's more important not to have stupid AI than to have good AI". Meier also omitted jets and helicopters because he thought players would not find obtaining new technologies in the endgame useful, and online multiplayer support because of the small number of online players ("if you had friends, you wouldn't need to play computer games"); he also did not believe that online play worked well with turn-based play. The game was developed for the IBM PC platform, which at the time had support for both 16-color EGA to 256-color VGA; Meier opted to support both 16-color and 256-color graphics to allow the game to run on both EGA/Tandy and VGA/MCGA systems.
"I’ve never been able to decide if it was a mistake to keep Civ isolated as long as I did", Meier wrote; while "as many eyes as possible" are beneficial during development, Meier and Shelley worked very quickly together, combining the roles of playtester, game designer, and programmer. Meier and Shelley neared the end of their development and started presenting the game to the rest of MicroProse for feedback towards publication. This process was slowed by the current vice president of development, who had taken over Meier's former position at the company. This vice president did not receive any financial bonuses for successful publication of Meier's games due to Meier's contract terms, forgoing any incentive to provide the needed resources to finish the game. The management had also expressed issue with the lack of a firm completion date, as according to Shelley, Meier would consider a game completed only when he felt he had completed it. Eventually the two got the required help for publication, with Shelley overseeing these processes and Meier making the necessary coding changes.
"One of my big rules has always been, 'double it, or cut it in half'", Meier wrote. He cut the map's size in half less than a month before Civilization's release after playtesting revealed that the previous size was too large and made for boring and repetitive gameplay. Other automated features, like city management, were modified to require more player involvement. They also eliminated a secondary branch of the technology tree with minor skills like beer brewing, and spent time reworking the existing technologies and units to make sure they felt appropriate and did not break the game. Most of the game was originally developed with art crafted by Meier, and MicroProse's art department helped to create most of the final assets, though some of Meier's original art was used. Shelley wrote out the "Civilopedia" entries for all the elements of the game and the game's large manual.
The name Civilization came late in the development process. MicroProse recognized at this point the 1980 Civilization board game may conflict with their video game, as it shared a similar theme including the technology tree. Meier had noted the board game's influence but considered it not as great as Empire or SimCity, while others have noted significant differences that made the video game far different from the board game such as the non-linearity introduced by Meier's technology tree. To avoid any potential legal issues, MicroProse negotiated a license to use the Civilization name from Avalon Hill. The addition of Meier's name to the title was from a current practice established by Stealey to attach games like Civilization that diverged from MicroProse's past catalog to Meier's name, so that players that played Meier's combat simulators and recognized Meier's name would give these new games a try. This approach worked, according to Meier, and he would continue this naming scheme for other titles in the future as a type of branding.
By the time the game was completed and ready for release, Meier estimated that it had cost $170,000 in development. Civilization was released in September 1991. Because of the animosity that MicroProse's management had towards Meier's games, there was very little promotion of the title, though interest in the game through word-of-mouth helped to boost sales. Following the release on the IBM PC, the game was ported to other platforms; Meier and Shelley provided this code to contractors hired by MicroProse to complete the ports.
Civilization was released with only single-player support, with the player working against multiple computer opponents. In 1991, Internet or online gaming was still in its infancy, so this option was not considered in Civilization's release. Over the next few years, as home Internet accessibility took off, MicroProse looked to develop an online version of Civilization. This led to the 1995 release of Sid Meier's CivNet. CivNet allowed for up to seven players to play the game, with computer opponents available to obtain up to six active civilizations. Games could be played either on a turn-based mode, or in a simultaneous mode where each player took their turn at the same time and only progressing to the next turn once all players have confirmed being finished that turn. The game, in addition to better support for Windows 3.1 and Windows 95, supported connectivity through LAN, primitive Internet play, modem, and direct serial link, and included a local hotseat mode. CivNet also included a map editor and a "king builder" to allow a player to customize the names and looks of their civilization as seen by other players.
According to Brian Reynolds, who led the development of Civilization II, MicroProse "sincerely believed that CivNet was going to be a much more important product" than the next single-player Civilization game that he and Jeff Briggs had started working on. Reynolds said that because their project was seen as a side effort with little risk, they were able to innovate new ideas into Civilization II. As a net result, CivNet was generally overshadowed by Civilization II which was released in the following year.
Civilization's critical success created a "golden period of MicroProse" where there was more potential for similar strategy games to succeed, according to Meier. This put stress on the company's direction and culture. Stealey wanted to continue to pursue the military-themed titles, while Meier wanted to continue his success with simulation games. Shelley left MicroProse in 1992 and joined Ensemble Studios, where he used his experience with Civilization to design the Age of Empires games. Stealey had pushed MicroProse to develop console and arcade-based versions of their games, but this put the company into debt, and Stealey eventually sold the company to Spectrum HoloByte in 1993; Spectrum HoloByte kept MicroProse as a separate company on acquisition.
Meier would continue and develop Civilization II along with Brian Reynolds, who served in a similar role to Shelley as design assistant, as well as help from Jeff Briggs and Douglas Kaufman. This game was released in early 1996, and is considered the first sequel of any Sid Meier game. Stealey eventually sold his shares in MicroProse and left the company, and Spectrum HoloByte opted to consolidate the two companies under the name MicroProse in 1996, eliminating numerous positions at MicroProse in the process. As a result, Meier, Briggs, and Reynolds all opted to leave the company and founded Firaxis, which by 2005 became a subsidiary of Take-Two. After a number of acquisitions and legal actions, the Civilization brand (both as a board game and video game) is now owned by Take-Two, and Firaxis, under Meier's oversight, continues to develop games in the Civilization series.
Civilization has been called one of the most important strategy games of all time, and has a loyal following of fans. This high level of interest has led to the creation of a number of free and open source versions and inspired similar games by other commercial developers.
Computer Gaming World stated that "a new Olympian in the genre of god games has truly emerged", comparing Civilization's importance to computer games to that of the wheel. The game was reviewed in 1992 in Dragon #183 by Hartley, Patricia, and Kirk Lesser in "The Role of Computers" column. The reviewers gave the game 5 out of 5 stars. They commented: "Civilization is one of the highest dollar-to-play-ratio entertainments we've enjoyed. The scope is enormous, the strategies border on being limitless, the excitement is genuinely high, and the experience is worth every dime of the game's purchase price."
Jeff Koke reviewed Civilization in Pyramid #2 (July/Aug., 1993), and stated that "Ultimately, there are games that are a lot flashier than Civilization, with cool graphics and animation, but there aren't many - or any - in my book that have the ability to absorb the player so totally and to provide an interesting, unique outcome each and every time it's played."
Civilization won the Origins Award in the category Best Military or Strategy Computer Game of 1991. A 1992 Computer Gaming World survey of wargames with modern settings gave the game five stars out of five, describing it as "more addictive than crack ... so rich and textured that the documentation is incomplete". In 1992 the magazine named it the Overall Game of the Year, in 1993 added the game to its Hall of Fame, and in 1996 chose Civilization as the best game of all time:
While some games might be equally addictive, none have sustained quite the level of rich, satisfying gameplay quite like Sid Meier's magnum opus. The blend of exploration, economics, conquest and diplomacy is augmented by the quintessential research and development model, as you struggle to erect the Pyramids, discover gunpowder, and launch a colonization spacecraft to Alpha Centauri. For its day, Civilization had the toughest computer opponents around - even taking into account the "cheats", that in most instances added rather than detracted from the game. Just when you think the game might bog down, you discover a new land, a new technology, another tough foe - and you tell yourself, "just one more game", even as the first rays of the new sun creep into your room ... the most acute case of game-lock we've ever felt.
A critic for Next Generation judged the Super NES version to be a disappointing port, with a cumbersome menu system (particularly that the "City" and "Production" windows are on separate screens), an unintuitive button configuration, and ugly scaled down graphics. However, he gave it a positive recommendation due to the strong gameplay and strategy of the original game: "if you've never taken a crack at this game before, be prepared to lose hours, even days, trying to conquer those pesky Babylonians." Sir Garnabus of GamePro, in contrast, was pleased with the Super NES version's interface, and said the graphics and audio are above that of a typical strategy game. He also said the game stood out among the Super NES's generally action-oriented library.
In 2000, GameSpot rated Civilization as the tenth most influential video game of all time. It was also ranked at fourth place on IGN's 2000 list of the top PC games of all time. In 2004, readers of Retro Gamer voted it as the 29th top retro game. In 2007, it was named one of the 16 most influential games in history at a German technology and games trade show Telespiele. In Poland, it was included in the retrospective lists of the best Amiga games by Wirtualna Polska (ranked ninth) and CHIP (ranked fifth). In 2012, Time named it one of the 100 greatest video games of all time. In 1994, PC Gamer US named Civilization the second best computer game ever. The editors wrote, "The depth of strategies possible is impressive, and the look and feel of the game will keep you playing and exploring for months. Truly a remarkable title." That same year, PC Gamer UK named its Windows release the sixth best computer game of all time, calling it Sid Meier's "crowning glory".
On March 12, 2007, The New York Times reported on a list of the ten most important video games of all time, the so-called game canon, including Civilization.
By the release of Civilization II in 1996, Civilization had sold over 850,000 copies. By 2001, sales had reached 1 million copies. Shelley stated in a 2016 interview that Civilization had sold 1.5 million copies.
In 2022, The Strong National Museum of Play inducted Sid Meier’s Civilization to its World Video Game Hall of Fame.
There have been several sequels to Civilization, including Civilization II (1996), Civilization III (2001), Civilization IV (2005), Civilization Revolution (2008), Civilization V (2010), and Civilization VI in 2016. In 1994, Meier produced a similar game titled Colonization.
Civilization is generally considered the first major game in the genre of "4X", with the four "X"s equating to "explore, expand, exploit, and exterminate", a term developed by Alan Emrich in promoting 1993's Master of Orion. While other video games with the principles of 4X had been released prior to Civilization, future 4X games would attribute some of their basic design principles to Civilization.
A famous supposed bug in the original game - later debunked - is that a computer-controlled Gandhi, normally a highly peaceful leader, could become a nuclear warmonger if provoked. It was theorized that the game started Gandhi's "aggression value" at 1 out of a maximum 255 possible for an 8-bit unsigned integer, making a computer-controlled Gandhi tend to avoid armed conflict. However, once a civilization achieves democracy as its form of government, its leader's aggression value falls by 2. Under normal arithmetic principles, Gandhi's "1" would be reduced to "-1", but because the value is an 8-bit unsigned integer, it supposedly wraps around to "255", causing Gandhi to suddenly become the most aggressive opponent in the game.
Interviewed in 2019, developer Brian Reynolds said with "99.99% certainty" that this story was apocryphal, recalling Gandhi's coded aggression level as being no lower than other peaceful leaders in the game, and doubting that a wraparound would have had the effect described. He noted that all leaders in the game become "pretty ornery" after their acquisition of nuclear weapons, and suggested that this behaviour simply seemed more surprising and memorable when it happened to Gandhi. Meier, in his autobiography, stated "That kind of bug comes from something called unsigned characters, which are not the default in the C programming language, and not something I used for the leader traits. Brian Reynolds wrote Civ II in C++, and he didn't use them, either. We received no complaints about a Gandhi bug when either game came out, nor did we send out any revisions for one. Gandhi's military aggressiveness score remained at 1 throughout the game." He then explains the overflow error story was made up in 2012. It spread from there to a Wikia entry, then eventually to Reddit, and was picked up by news sites like Kotaku and Geek.com. The story may have originated from the fact that 2010's Civilization V was deliberately written with Gandhi having an affinity for nuclear weapons, added as a joke by developer Jon Shafer. The misinformation around this bug led to the meme known as "Nuclear Gandhi".
Another relic of Civilization was the nature of combat where a military unit from earlier civilization periods could remain in play through modern times, gaining combat bonuses due to veteran proficiency, leading to these primitive units easily beating out modern technology against all common sense, with the common example of a veteran phalanx unit able to fend off a battleship. Meier noted that this resulted from not anticipating how players would use units, expecting them to have used their forces more like a war-based board game to protect borders and maintain zones of control rather than creating "stacks of doom". Future civilization games have had many changes in combat systems to prevent such oddities, though these games do allow for such random victories.
The 1999 game Sid Meier's Alpha Centauri was also created by Meier and is in the same genre, but with a futuristic/space theme; many of the interface and gameplay innovations in this game eventually made their way into Civilization III and IV. Alpha Centauri is not actually a sequel to Civilization, despite beginning with the same event that ends Civilization and Civilization II: a crewed spacecraft from Earth arrives in the Alpha Centauri star system. Firaxis' 2014 game Civilization: Beyond Earth, although bearing the name of the main series, is a reimagining of Alpha Centauri running on the engine of Civilization V.
A 1994 Computer Gaming World survey of space war games stated that "the lesson of this incredibly popular wargame has not been lost on the software community, and technological research popped up all over the place in 1993", citing Spaceward Ho! and Master of Orion as examples. That year MicroProse published Master of Magic, a similar game but embedded in a medieval-fantasy setting where instead of technologies the player (a powerful wizard) develops spells, among other things. In 1999, Activision released Civilization: Call to Power, a sequel of sorts to Civilization II but created by a completely different design team. Call to Power spawned a sequel in 2000, but by then Activision had sold the rights to the Civilization name and could only call it Call to Power II.
An open source clone of Civilization has been developed under the name of Freeciv, with the slogan "'Cause civilization should be free." This game can be configured to match the rules of either Civilization or Civilization II. Another game that partially clones Civilization is a public domain game called C-evo. | [
{
"paragraph_id": 0,
"text": "Sid Meier's Civilization is a 1991 turn-based strategy 4X game developed and published by MicroProse. The game was originally developed for MS-DOS running on a PC, and it has undergone numerous revisions for various platforms. The player is tasked with leading an entire human civilization over the course of several millennia by controlling various areas such as urban development, exploration, government, trade, research, and military. The player can control individual units and advance the exploration, conquest and settlement of the game's world. The player can also make such decisions as setting forms of government, tax rates and research priorities. The player's civilization is in competition with other computer-controlled civilizations, with which the player can enter diplomatic relationships that can either end in alliances or lead to war.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Civilization was designed by Sid Meier and Bruce Shelley following the successes of Silent Service, Sid Meier's Pirates! and Railroad Tycoon. Civilization has sold 1.5 million copies since its release and is considered one of the most influential computer games in history due to its establishment of the 4X genre. In addition to its commercial and critical success, the game has been deemed pedagogically valuable due to its presentation of historical relationships. A multiplayer remake, Sid Meier's CivNet, was released for the PC in 1995. Civilization was followed by several sequels starting with Civilization II, with similar or modified scenarios.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Civilization is a turn-based single-player strategy game. The player takes on the role of the ruler of a civilization, starting with one (or occasionally two) settler units, and attempts to build an empire in competition with two to seven other civilizations. The game requires a fair amount of micromanagement (although less than other simulation games). Along with the larger tasks of exploration, warfare and diplomacy, the player has to make decisions about where to build new cities, which improvements or units to build in each city, which advances in knowledge should be sought (and at what rate), and how to transform the land surrounding the cities for maximum benefit. From time to time the player's towns may be harassed by barbarians, units with no specific nationality and no named leader. These threats only come from huts, unclaimed land or sea, so that over time and turns of exploration, there are fewer and fewer places from which barbarians will emanate.",
"title": "Gameplay"
},
{
"paragraph_id": 3,
"text": "Before the game begins, the player chooses which historical or current civilization to play. In contrast to later games in the Civilization series, this is largely a cosmetic choice, affecting titles, city names, musical heralds, and color. The choice does affect their starting position on the \"Play on Earth\" map, and thus different resources in one's initial cities, but has no effect on starting position when starting a random world game or a customized world game. The player's choice of civilization also prevents the computer from being able to play as that civilization or the other civilization of the same color, and since computer-controlled opponents display certain traits of their civilizations this affects gameplay as well. The Aztecs are both fiercely expansionist and generally extremely wealthy, for example. Other civilizations include the Americans, the Mongols, and Romans. Each civilization is led by a famous historical figure, such as Mahatma Gandhi for India.",
"title": "Gameplay"
},
{
"paragraph_id": 4,
"text": "The scope of Civilization is larger than most other games. The game begins in 4000 BC, before the Bronze Age, and can last through to AD 2100 (on the easiest setting) with Space Age and \"future technologies\". At the start of the game there are no cities anywhere in the world: the player controls one or two settler units, which can be used to found new cities in appropriate sites (and those cities may build other settler units, which can go out and found new cities, thus expanding the empire). Settlers can also alter terrain, build improvements such as mines and irrigation, build roads to connect cities, and later in the game they can construct railroads which offer unlimited movement.",
"title": "Gameplay"
},
{
"paragraph_id": 5,
"text": "As time advances, new technologies are developed; these technologies are the primary way in which the game changes and grows. At the start, players choose from advances such as pottery, the wheel, and the alphabet to, near the end of the game, nuclear fission and spaceflight. Players can gain a large advantage if their civilization is the first to learn a particular technology (the secrets of flight, for example) and put it to use in a military or other context. Most advances give access to new units, city improvements or derivative technologies: for example, the chariot unit becomes available after the wheel is developed, and the granary building becomes available to build after pottery is developed. The whole system of advancements from beginning to end is called the technology tree, or simply the Tech tree; this concept has been adopted in many other strategy games. Since only one tech may be \"researched\" at any given time, the order in which technologies are chosen makes a considerable difference in the outcome of the game and generally reflects the player's preferred style of gameplay.",
"title": "Gameplay"
},
{
"paragraph_id": 6,
"text": "Players can also build Wonders of the World in each of the epochs of the game, subject only to obtaining the prerequisite knowledge. These wonders are important achievements of society, science, culture and defense, ranging from the Pyramids and the Great Wall in the Ancient age, to Copernicus' Observatory and Magellan's Expedition in the middle period, up to the Apollo program, the United Nations, and the Manhattan Project in the modern era. Each wonder can only be built once in the world, and requires a lot of resources to build, far more than most other city buildings or units. Wonders provide unique benefits to the controlling civilization. For example, Magellan's Expedition increases the movement rate of naval units. Wonders typically affect either the city in which they are built (for example, the Colossus), every city on the continent (for example, J.S. Bach's Cathedral), or the civilization as a whole (for example, Darwin's Voyage). Some wonders are made obsolete by new technologies.",
"title": "Gameplay"
},
{
"paragraph_id": 7,
"text": "The game can be won by conquering all other civilizations or by winning the space race by reaching the star system of Alpha Centauri.",
"title": "Gameplay"
},
{
"paragraph_id": 8,
"text": "British designer Francis Tresham released his Civilization board game in 1980 under his company Hartland Trefoil. Avalon Hill had obtained the rights to publish it in the United States in 1981.",
"title": "Development"
},
{
"paragraph_id": 9,
"text": "There were at least two attempts to make a computerized version of Tresham's game prior to 1990. Danielle Bunten Berry planned to start work on the game after completing M.U.L.E. in 1983, and again in 1985, after completing The Seven Cities of Gold at Electronic Arts. In 1983 Bunten and producer Joe Ybarra opted to first do Seven Cities of Gold. The success of Seven Cities in 1985 in turn led to a sequel, Heart of Africa. Bunten never returned to the idea of Civilization. Don Daglow, designer of Utopia, the first simulation game, began work programming a version of Civilization in 1987. He dropped the project, however, when he was offered an executive position at Brøderbund, and never returned to the game.",
"title": "Development"
},
{
"paragraph_id": 10,
"text": "Sid Meier and Bill Stealey co-founded MicroProse in 1982 to develop flight simulators and other military strategy video games based on Stealey's past experiences as a United States Air Force pilot. Around 1989, Meier wanted to expand his repertoire beyond these types of games, as just having finished F-19 Stealth Fighter (1988, 1990), he said \"Everything I thought was cool about a flight simulator had gone into that game.\" He took to heart the success of the new god game genre, in particular SimCity (1989) and Populous (1989). Specifically with SimCity, Meier recognized that video games could still be entertaining based on building something up. By then, Meier was not an official employee of MicroProse but worked under contract where the company paid him upfront for game development, a large payment on delivery of the game, and additional royalties on each game of his sold.",
"title": "Development"
},
{
"paragraph_id": 11,
"text": "MicroProse had hired a number of Avalon Hill game designers, including Bruce Shelley. Among other works, Shelley had been responsible for adapting the railroad-based 1829 board game developed by Tresham into 1830: The Game of Railroads and Robber Barons. Shelley had joined MicroProse finding that the board game market was weakening in contrast to the video game market, and initially worked on F-19 Stealth Fighter. Meier recognized Shelley's abilities and background in game design and took him on as personal assistant designer to brainstorm new game ideas. The two initially worked on ideas for Covert Action, but had put these aside when they came up with the concepts for Railroad Tycoon (1990), based loosely on the 1829/1830 board games. Railroad Tycoon was generally well received at its release, but the title did not fit within the nature of flight simulators and military strategy from MicroProse's previous catalog. Meier and Shelley had started a sequel to Railroad Tycoon shortly after its release, but Stealey canceled the project.",
"title": "Development"
},
{
"paragraph_id": 12,
"text": "One positive aspect both had taken from Railroad Tycoon was the idea of multiple smaller systems working together at the same time and the player having to manage them. Both Meier and Shelley recognized that the complex interactions between these systems led players to \"make a lot of interesting decisions\", and that ruling a whole civilization would readily work well with these underlying systems. Some time later, both discussed their love of the original Empire computer games, and Meier challenged Shelley to give him ten things he would change about Empire; Shelley provided him with twelve. Around May 1990, Meier presented Shelley with a 5-1/4\" floppy disk which contained the first prototype of Civilization based on their past discussions and Shelley's list.",
"title": "Development"
},
{
"paragraph_id": 13,
"text": "Meier described his development process as sculpting with clay. His prototype took elements from Empire, Railroad Tycoon, SimCity and the Civilization board game. This initial version of this game was a real-time simulation, with the player defining zones for their population to grow similar to zoning in SimCity. Meier and Shelley went back and forth with this, with Shelley providing suggestions based on his playthrough and acting as the game's producer, and Meier coding and reworking the game to address these points, and otherwise without involvement of other MicroProse staff. During this period, Stealey and the other managers became concerned that this game did not fit MicroProse's general catalog as strategy computer games had not yet proven successful. A few months into the development, Stealey requested them to put the project on hold and complete Covert Action, after which they could go back to their new game. Meier and Shelley completed Covert Action which was published in 1990.",
"title": "Development"
},
{
"paragraph_id": 14,
"text": "Once Covert Action was released, Meier and Shelley returned to the prototype. The time away from the project allowed them to recognize that the real-time aspect was not working well, and reworked the game to become turn-based and dropped the zoning aspect, a change that Meier described as \"like tossing the clay in the trash and getting a new lump\". They incorporated elements of city management and military aspect from Empire, including creating individual military units as well as settler units that replaced the functionality of the zoning approach. Meier felt adding military and combat to the game was necessary: \"The game really isn't about being civilized. The competition is what makes the game fun and the players play their best. At times, you have to make the player uncomfortable for the good of the player.\" Meier also opted to include a technology tree that would help to open the game to many more choices to the player as it continued, creating a non-linear experience. Meier felt players would be able to use the technology tree to adopt a style of play and from which they could use technologies to barter with the other opponents. While the game relies on established recorded history, Meier admitted he did not spend much time in research, usually only to assure the proper chronology or spellings; Shelley noted that they wanted to design for fun, not accuracy, and that \"Everything we needed was pretty much available in the children’s section of the library.\"",
"title": "Development"
},
{
"paragraph_id": 15,
"text": "Computer Gaming World reported in 1994 that \"Sid Meier has stated on numerous occasions that he emphasizes the 'fun parts' of a simulation and throws out the rest\". Meier described the process as \"Add another bit [of clay]—no, that went too far. Scrape it off\". He eliminated the potential for any civilization to fall on its own, believing this would be punishing to the player. \"Though historically accurate\", Meier said, \"The moment the Krakatoa volcano blew up, or the bubonic plague came marching through, all anybody wanted to do was reload from a saved game\". Meier omitted multiplayer alliances because the computer used them too effectively, causing players to think that it was cheating. He said that by contrast, minefields and minesweepers caused the computer to do \"stupid things ... If you've got a feature that makes the AI look stupid, take it out. It's more important not to have stupid AI than to have good AI\". Meier also omitted jets and helicopters because he thought players would not find obtaining new technologies in the endgame useful, and online multiplayer support because of the small number of online players (\"if you had friends, you wouldn't need to play computer games\"); he also did not believe that online play worked well with turn-based play. The game was developed for the IBM PC platform, which at the time had support for both 16-color EGA to 256-color VGA; Meier opted to support both 16-color and 256-color graphics to allow the game to run on both EGA/Tandy and VGA/MCGA systems.",
"title": "Development"
},
{
"paragraph_id": 16,
"text": "\"I’ve never been able to decide if it was a mistake to keep Civ isolated as long as I did\", Meier wrote; while \"as many eyes as possible\" are beneficial during development, Meier and Shelley worked very quickly together, combining the roles of playtester, game designer, and programmer. Meier and Shelley neared the end of their development and started presenting the game to the rest of MicroProse for feedback towards publication. This process was slowed by the current vice president of development, who had taken over Meier's former position at the company. This vice president did not receive any financial bonuses for successful publication of Meier's games due to Meier's contract terms, forgoing any incentive to provide the needed resources to finish the game. The management had also expressed issue with the lack of a firm completion date, as according to Shelley, Meier would consider a game completed only when he felt he had completed it. Eventually the two got the required help for publication, with Shelley overseeing these processes and Meier making the necessary coding changes.",
"title": "Development"
},
{
"paragraph_id": 17,
"text": "\"One of my big rules has always been, 'double it, or cut it in half'\", Meier wrote. He cut the map's size in half less than a month before Civilization's release after playtesting revealed that the previous size was too large and made for boring and repetitive gameplay. Other automated features, like city management, were modified to require more player involvement. They also eliminated a secondary branch of the technology tree with minor skills like beer brewing, and spent time reworking the existing technologies and units to make sure they felt appropriate and did not break the game. Most of the game was originally developed with art crafted by Meier, and MicroProse's art department helped to create most of the final assets, though some of Meier's original art was used. Shelley wrote out the \"Civilopedia\" entries for all the elements of the game and the game's large manual.",
"title": "Development"
},
{
"paragraph_id": 18,
"text": "The name Civilization came late in the development process. MicroProse recognized at this point the 1980 Civilization board game may conflict with their video game, as it shared a similar theme including the technology tree. Meier had noted the board game's influence but considered it not as great as Empire or SimCity, while others have noted significant differences that made the video game far different from the board game such as the non-linearity introduced by Meier's technology tree. To avoid any potential legal issues, MicroProse negotiated a license to use the Civilization name from Avalon Hill. The addition of Meier's name to the title was from a current practice established by Stealey to attach games like Civilization that diverged from MicroProse's past catalog to Meier's name, so that players that played Meier's combat simulators and recognized Meier's name would give these new games a try. This approach worked, according to Meier, and he would continue this naming scheme for other titles in the future as a type of branding.",
"title": "Development"
},
{
"paragraph_id": 19,
"text": "By the time the game was completed and ready for release, Meier estimated that it had cost $170,000 in development. Civilization was released in September 1991. Because of the animosity that MicroProse's management had towards Meier's games, there was very little promotion of the title, though interest in the game through word-of-mouth helped to boost sales. Following the release on the IBM PC, the game was ported to other platforms; Meier and Shelley provided this code to contractors hired by MicroProse to complete the ports.",
"title": "Development"
},
{
"paragraph_id": 20,
"text": "Civilization was released with only single-player support, with the player working against multiple computer opponents. In 1991, Internet or online gaming was still in its infancy, so this option was not considered in Civilization's release. Over the next few years, as home Internet accessibility took off, MicroProse looked to develop an online version of Civilization. This led to the 1995 release of Sid Meier's CivNet. CivNet allowed for up to seven players to play the game, with computer opponents available to obtain up to six active civilizations. Games could be played either on a turn-based mode, or in a simultaneous mode where each player took their turn at the same time and only progressing to the next turn once all players have confirmed being finished that turn. The game, in addition to better support for Windows 3.1 and Windows 95, supported connectivity through LAN, primitive Internet play, modem, and direct serial link, and included a local hotseat mode. CivNet also included a map editor and a \"king builder\" to allow a player to customize the names and looks of their civilization as seen by other players.",
"title": "Development"
},
{
"paragraph_id": 21,
"text": "According to Brian Reynolds, who led the development of Civilization II, MicroProse \"sincerely believed that CivNet was going to be a much more important product\" than the next single-player Civilization game that he and Jeff Briggs had started working on. Reynolds said that because their project was seen as a side effort with little risk, they were able to innovate new ideas into Civilization II. As a net result, CivNet was generally overshadowed by Civilization II which was released in the following year.",
"title": "Development"
},
{
"paragraph_id": 22,
"text": "Civilization's critical success created a \"golden period of MicroProse\" where there was more potential for similar strategy games to succeed, according to Meier. This put stress on the company's direction and culture. Stealey wanted to continue to pursue the military-themed titles, while Meier wanted to continue his success with simulation games. Shelley left MicroProse in 1992 and joined Ensemble Studios, where he used his experience with Civilization to design the Age of Empires games. Stealey had pushed MicroProse to develop console and arcade-based versions of their games, but this put the company into debt, and Stealey eventually sold the company to Spectrum HoloByte in 1993; Spectrum HoloByte kept MicroProse as a separate company on acquisition.",
"title": "Development"
},
{
"paragraph_id": 23,
"text": "Meier would continue and develop Civilization II along with Brian Reynolds, who served in a similar role to Shelley as design assistant, as well as help from Jeff Briggs and Douglas Kaufman. This game was released in early 1996, and is considered the first sequel of any Sid Meier game. Stealey eventually sold his shares in MicroProse and left the company, and Spectrum HoloByte opted to consolidate the two companies under the name MicroProse in 1996, eliminating numerous positions at MicroProse in the process. As a result, Meier, Briggs, and Reynolds all opted to leave the company and founded Firaxis, which by 2005 became a subsidiary of Take-Two. After a number of acquisitions and legal actions, the Civilization brand (both as a board game and video game) is now owned by Take-Two, and Firaxis, under Meier's oversight, continues to develop games in the Civilization series.",
"title": "Development"
},
{
"paragraph_id": 24,
"text": "Civilization has been called one of the most important strategy games of all time, and has a loyal following of fans. This high level of interest has led to the creation of a number of free and open source versions and inspired similar games by other commercial developers.",
"title": "Reception"
},
{
"paragraph_id": 25,
"text": "Computer Gaming World stated that \"a new Olympian in the genre of god games has truly emerged\", comparing Civilization's importance to computer games to that of the wheel. The game was reviewed in 1992 in Dragon #183 by Hartley, Patricia, and Kirk Lesser in \"The Role of Computers\" column. The reviewers gave the game 5 out of 5 stars. They commented: \"Civilization is one of the highest dollar-to-play-ratio entertainments we've enjoyed. The scope is enormous, the strategies border on being limitless, the excitement is genuinely high, and the experience is worth every dime of the game's purchase price.\"",
"title": "Reception"
},
{
"paragraph_id": 26,
"text": "Jeff Koke reviewed Civilization in Pyramid #2 (July/Aug., 1993), and stated that \"Ultimately, there are games that are a lot flashier than Civilization, with cool graphics and animation, but there aren't many - or any - in my book that have the ability to absorb the player so totally and to provide an interesting, unique outcome each and every time it's played.\"",
"title": "Reception"
},
{
"paragraph_id": 27,
"text": "Civilization won the Origins Award in the category Best Military or Strategy Computer Game of 1991. A 1992 Computer Gaming World survey of wargames with modern settings gave the game five stars out of five, describing it as \"more addictive than crack ... so rich and textured that the documentation is incomplete\". In 1992 the magazine named it the Overall Game of the Year, in 1993 added the game to its Hall of Fame, and in 1996 chose Civilization as the best game of all time:",
"title": "Reception"
},
{
"paragraph_id": 28,
"text": "While some games might be equally addictive, none have sustained quite the level of rich, satisfying gameplay quite like Sid Meier's magnum opus. The blend of exploration, economics, conquest and diplomacy is augmented by the quintessential research and development model, as you struggle to erect the Pyramids, discover gunpowder, and launch a colonization spacecraft to Alpha Centauri. For its day, Civilization had the toughest computer opponents around - even taking into account the \"cheats\", that in most instances added rather than detracted from the game. Just when you think the game might bog down, you discover a new land, a new technology, another tough foe - and you tell yourself, \"just one more game\", even as the first rays of the new sun creep into your room ... the most acute case of game-lock we've ever felt.",
"title": "Reception"
},
{
"paragraph_id": 29,
"text": "A critic for Next Generation judged the Super NES version to be a disappointing port, with a cumbersome menu system (particularly that the \"City\" and \"Production\" windows are on separate screens), an unintuitive button configuration, and ugly scaled down graphics. However, he gave it a positive recommendation due to the strong gameplay and strategy of the original game: \"if you've never taken a crack at this game before, be prepared to lose hours, even days, trying to conquer those pesky Babylonians.\" Sir Garnabus of GamePro, in contrast, was pleased with the Super NES version's interface, and said the graphics and audio are above that of a typical strategy game. He also said the game stood out among the Super NES's generally action-oriented library.",
"title": "Reception"
},
{
"paragraph_id": 30,
"text": "In 2000, GameSpot rated Civilization as the tenth most influential video game of all time. It was also ranked at fourth place on IGN's 2000 list of the top PC games of all time. In 2004, readers of Retro Gamer voted it as the 29th top retro game. In 2007, it was named one of the 16 most influential games in history at a German technology and games trade show Telespiele. In Poland, it was included in the retrospective lists of the best Amiga games by Wirtualna Polska (ranked ninth) and CHIP (ranked fifth). In 2012, Time named it one of the 100 greatest video games of all time. In 1994, PC Gamer US named Civilization the second best computer game ever. The editors wrote, \"The depth of strategies possible is impressive, and the look and feel of the game will keep you playing and exploring for months. Truly a remarkable title.\" That same year, PC Gamer UK named its Windows release the sixth best computer game of all time, calling it Sid Meier's \"crowning glory\".",
"title": "Reception"
},
{
"paragraph_id": 31,
"text": "On March 12, 2007, The New York Times reported on a list of the ten most important video games of all time, the so-called game canon, including Civilization.",
"title": "Reception"
},
{
"paragraph_id": 32,
"text": "By the release of Civilization II in 1996, Civilization had sold over 850,000 copies. By 2001, sales had reached 1 million copies. Shelley stated in a 2016 interview that Civilization had sold 1.5 million copies.",
"title": "Reception"
},
{
"paragraph_id": 33,
"text": "In 2022, The Strong National Museum of Play inducted Sid Meier’s Civilization to its World Video Game Hall of Fame.",
"title": "Reception"
},
{
"paragraph_id": 34,
"text": "There have been several sequels to Civilization, including Civilization II (1996), Civilization III (2001), Civilization IV (2005), Civilization Revolution (2008), Civilization V (2010), and Civilization VI in 2016. In 1994, Meier produced a similar game titled Colonization.",
"title": "Legacy"
},
{
"paragraph_id": 35,
"text": "Civilization is generally considered the first major game in the genre of \"4X\", with the four \"X\"s equating to \"explore, expand, exploit, and exterminate\", a term developed by Alan Emrich in promoting 1993's Master of Orion. While other video games with the principles of 4X had been released prior to Civilization, future 4X games would attribute some of their basic design principles to Civilization.",
"title": "Legacy"
},
{
"paragraph_id": 36,
"text": "A famous supposed bug in the original game - later debunked - is that a computer-controlled Gandhi, normally a highly peaceful leader, could become a nuclear warmonger if provoked. It was theorized that the game started Gandhi's \"aggression value\" at 1 out of a maximum 255 possible for an 8-bit unsigned integer, making a computer-controlled Gandhi tend to avoid armed conflict. However, once a civilization achieves democracy as its form of government, its leader's aggression value falls by 2. Under normal arithmetic principles, Gandhi's \"1\" would be reduced to \"-1\", but because the value is an 8-bit unsigned integer, it supposedly wraps around to \"255\", causing Gandhi to suddenly become the most aggressive opponent in the game.",
"title": "Legacy"
},
{
"paragraph_id": 37,
"text": "Interviewed in 2019, developer Brian Reynolds said with \"99.99% certainty\" that this story was apocryphal, recalling Gandhi's coded aggression level as being no lower than other peaceful leaders in the game, and doubting that a wraparound would have had the effect described. He noted that all leaders in the game become \"pretty ornery\" after their acquisition of nuclear weapons, and suggested that this behaviour simply seemed more surprising and memorable when it happened to Gandhi. Meier, in his autobiography, stated \"That kind of bug comes from something called unsigned characters, which are not the default in the C programming language, and not something I used for the leader traits. Brian Reynolds wrote Civ II in C++, and he didn't use them, either. We received no complaints about a Gandhi bug when either game came out, nor did we send out any revisions for one. Gandhi's military aggressiveness score remained at 1 throughout the game.\" He then explains the overflow error story was made up in 2012. It spread from there to a Wikia entry, then eventually to Reddit, and was picked up by news sites like Kotaku and Geek.com. The story may have originated from the fact that 2010's Civilization V was deliberately written with Gandhi having an affinity for nuclear weapons, added as a joke by developer Jon Shafer. The misinformation around this bug led to the meme known as \"Nuclear Gandhi\".",
"title": "Legacy"
},
{
"paragraph_id": 38,
"text": "Another relic of Civilization was the nature of combat where a military unit from earlier civilization periods could remain in play through modern times, gaining combat bonuses due to veteran proficiency, leading to these primitive units easily beating out modern technology against all common sense, with the common example of a veteran phalanx unit able to fend off a battleship. Meier noted that this resulted from not anticipating how players would use units, expecting them to have used their forces more like a war-based board game to protect borders and maintain zones of control rather than creating \"stacks of doom\". Future civilization games have had many changes in combat systems to prevent such oddities, though these games do allow for such random victories.",
"title": "Legacy"
},
{
"paragraph_id": 39,
"text": "The 1999 game Sid Meier's Alpha Centauri was also created by Meier and is in the same genre, but with a futuristic/space theme; many of the interface and gameplay innovations in this game eventually made their way into Civilization III and IV. Alpha Centauri is not actually a sequel to Civilization, despite beginning with the same event that ends Civilization and Civilization II: a crewed spacecraft from Earth arrives in the Alpha Centauri star system. Firaxis' 2014 game Civilization: Beyond Earth, although bearing the name of the main series, is a reimagining of Alpha Centauri running on the engine of Civilization V.",
"title": "Legacy"
},
{
"paragraph_id": 40,
"text": "A 1994 Computer Gaming World survey of space war games stated that \"the lesson of this incredibly popular wargame has not been lost on the software community, and technological research popped up all over the place in 1993\", citing Spaceward Ho! and Master of Orion as examples. That year MicroProse published Master of Magic, a similar game but embedded in a medieval-fantasy setting where instead of technologies the player (a powerful wizard) develops spells, among other things. In 1999, Activision released Civilization: Call to Power, a sequel of sorts to Civilization II but created by a completely different design team. Call to Power spawned a sequel in 2000, but by then Activision had sold the rights to the Civilization name and could only call it Call to Power II.",
"title": "Legacy"
},
{
"paragraph_id": 41,
"text": "An open source clone of Civilization has been developed under the name of Freeciv, with the slogan \"'Cause civilization should be free.\" This game can be configured to match the rules of either Civilization or Civilization II. Another game that partially clones Civilization is a public domain game called C-evo.",
"title": "Legacy"
}
] | Sid Meier's Civilization is a 1991 turn-based strategy 4X game developed and published by MicroProse. The game was originally developed for MS-DOS running on a PC, and it has undergone numerous revisions for various platforms. The player is tasked with leading an entire human civilization over the course of several millennia by controlling various areas such as urban development, exploration, government, trade, research, and military. The player can control individual units and advance the exploration, conquest and settlement of the game's world. The player can also make such decisions as setting forms of government, tax rates and research priorities. The player's civilization is in competition with other computer-controlled civilizations, with which the player can enter diplomatic relationships that can either end in alliances or lead to war. Civilization was designed by Sid Meier and Bruce Shelley following the successes of Silent Service, Sid Meier's Pirates! and Railroad Tycoon. Civilization has sold 1.5 million copies since its release and is considered one of the most influential computer games in history due to its establishment of the 4X genre. In addition to its commercial and critical success, the game has been deemed pedagogically valuable due to its presentation of historical relationships. A multiplayer remake, Sid Meier's CivNet, was released for the PC in 1995. Civilization was followed by several sequels starting with Civilization II, with similar or modified scenarios. | 2001-11-08T18:04:24Z | 2023-12-25T16:16:35Z | [
"Template:See also",
"Template:Webarchive",
"Template:In lang",
"Template:Commons category",
"Template:Civilization",
"Template:Authority control",
"Template:Redirect",
"Template:Video game reviews",
"Template:ISBN",
"Template:Cite web",
"Template:Cite book",
"Template:Short description",
"Template:Use mdy dates",
"Template:Infobox video game",
"Template:' \"",
"Template:Blockquote",
"Template:Reflist",
"Template:Cite news",
"Template:Cbignore",
"Template:Clear",
"Template:For",
"Template:R",
"Template:'s",
"Template:External media",
"Template:Cite magazine",
"Template:Portal bar"
] | https://en.wikipedia.org/wiki/Civilization_(video_game) |
6,260 | Claude Debussy | (Achille) Claude Debussy (French: [aʃil klod dəbysi]; 22 August 1862 – 25 March 1918) was a French composer. He is sometimes seen as the first Impressionist composer, although he vigorously rejected the term. He was among the most influential composers of the late 19th and early 20th centuries.
Born to a family of modest means and little cultural involvement, Debussy showed enough musical talent to be admitted at the age of ten to France's leading music college, the Conservatoire de Paris. He originally studied the piano, but found his vocation in innovative composition, despite the disapproval of the Conservatoire's conservative professors. He took many years to develop his mature style, and was nearly 40 when he achieved international fame in 1902 with the only opera he completed, Pelléas et Mélisande.
Debussy's orchestral works include Prélude à l'après-midi d'un faune (1894), Nocturnes (1897–1899) and Images (1905–1912). His music was to a considerable extent a reaction against Wagner and the German musical tradition. He regarded the classical symphony as obsolete and sought an alternative in his "symphonic sketches", La mer (1903–1905). His piano works include sets of 24 Préludes and 12 Études. Throughout his career he wrote mélodies based on a wide variety of poetry, including his own. He was greatly influenced by the Symbolist poetic movement of the later 19th century. A small number of works, including the early La Damoiselle élue and the late Le Martyre de saint Sébastien have important parts for chorus. In his final years, he focused on chamber music, completing three of six planned sonatas for different combinations of instruments.
With early influences including Russian and Far Eastern music and works by Chopin, Debussy developed his own style of harmony and orchestral colouring, derided – and unsuccessfully resisted – by much of the musical establishment of the day. His works have strongly influenced a wide range of composers including Béla Bartók, Olivier Messiaen, George Benjamin, and the jazz pianist and composer Bill Evans. Debussy died from cancer at his home in Paris at the age of 55 after a composing career of a little more than 30 years.
Debussy was born on 22 August 1862 in Saint-Germain-en-Laye, Seine-et-Oise, on the north-west fringes of Paris. He was the eldest of the five children of Manuel-Achille Debussy and his wife, Victorine, née Manoury. Debussy senior ran a china shop and his wife was a seamstress. The shop was unsuccessful, and closed in 1864; the family moved to Paris, first living with Victorine's mother, in Clichy, and, from 1868, in their own apartment in the Rue Saint-Honoré. Manuel worked in a printing factory.
In 1870, to escape the siege of Paris during the Franco-Prussian War, Debussy's pregnant mother took him and his sister Adèle to their paternal aunt's home in Cannes, where they remained until the following year. During his stay in Cannes, the seven-year-old Debussy had his first piano lessons; his aunt paid for him to study with an Italian musician, Jean Cerutti. Manuel Debussy remained in Paris and joined the forces of the Commune; after its defeat by French government troops in 1871 he was sentenced to four years' imprisonment, of which he only served one year. His fellow Communard prisoners included his friend Charles de Sivry, a musician. Sivry's mother, Antoinette Mauté de Fleurville, gave piano lessons, and at his instigation the young Debussy became one of her pupils.
Debussy's talents soon became evident, and in 1872, aged ten, he was admitted to the Conservatoire de Paris, where he remained a student for the next eleven years. He first joined the piano class of Antoine François Marmontel, and studied solfège with Albert Lavignac and, later, composition with Ernest Guiraud, harmony with Émile Durand, and organ with César Franck. The course included music history and theory studies with Louis-Albert Bourgault-Ducoudray, but it is not certain that Debussy, who was apt to skip classes, actually attended these.
At the Conservatoire, Debussy initially made good progress. Marmontel said of him, "A charming child, a truly artistic temperament; much can be expected of him". Another teacher was less impressed: Émile Durand wrote in a report, "Debussy would be an excellent pupil if he were less sketchy and less cavalier." A year later he described Debussy as "desperately careless". In July 1874 Debussy received the award of deuxième accessit for his performance as soloist in the first movement of Chopin's Second Piano Concerto at the Conservatoire's annual competition. He was a fine pianist and an outstanding sight reader, who could have had a professional career had he wished, but he was only intermittently diligent in his studies. He advanced to premier accessit in 1875 and second prize in 1877, but failed at the competitions in 1878 and 1879. These failures made him ineligible to continue in the Conservatoire's piano classes, but he remained a student for harmony, solfège and, later, composition.
With Marmontel's help Debussy secured a summer vacation job in 1879 as resident pianist at the Château de Chenonceau, where he rapidly acquired a taste for luxury that was to remain with him all his life. His first compositions date from this period, two settings of poems by Alfred de Musset: "Ballade à la lune" and "Madrid, princesse des Espagnes". The following year he secured a job as pianist in the household of Nadezhda von Meck, the patroness of Tchaikovsky. He travelled with her family for the summers of 1880 to 1882, staying at various places in France, Switzerland and Italy, as well as at her home in Moscow. He composed his Piano Trio in G major for von Meck's ensemble, and made a transcription for piano duet of three dances from Tchaikovsky's Swan Lake.
At the end of 1880 Debussy, while continuing his studies at the Conservatoire, was engaged as accompanist for Marie Moreau-Sainti's singing class; he took this role for four years. Among the members of the class was Marie Vasnier; Debussy was greatly taken with her, and she inspired him to compose: he wrote 27 songs dedicated to her during their seven-year relationship. She was the wife of Henri Vasnier, a prominent civil servant, and much younger than her husband. She soon became Debussy's lover as well as his muse. Whether Vasnier was content to tolerate his wife's affair with the young student or was simply unaware of it is not clear, but he and Debussy remained on excellent terms, and he continued to encourage the composer in his career.
At the Conservatoire, Debussy incurred the disapproval of the faculty, particularly his composition teacher, Guiraud, for his failure to follow the orthodox rules of composition then prevailing. Nevertheless, in 1884 Debussy won France's most prestigious musical award, the Prix de Rome, with his cantata L'enfant prodigue. The Prix carried with it a residence at the Villa Medici, the French Academy in Rome, to further the winner's studies. Debussy was there from January 1885 to March 1887, with three or possibly four absences of several weeks when he returned to France, chiefly to see Marie Vasnier.
Initially Debussy found the artistic atmosphere of the Villa Medici stifling, the company boorish, the food bad, and the accommodation "abominable". Neither did he delight in Italian opera, as he found the operas of Donizetti and Verdi not to his taste. He was much more impressed by the music of the 16th-century composers Palestrina and Lassus, which he heard at Santa Maria dell'Anima: "The only church music I will accept". He was often depressed and unable to compose, but he was inspired by Franz Liszt, who visited the students and played for them. In June 1885, Debussy wrote of his desire to follow his own way, saying, "I am sure the Institute would not approve, for, naturally it regards the path which it ordains as the only right one. But there is no help for it! I am too enamoured of my freedom, too fond of my own ideas!"
Debussy finally composed four pieces that were submitted to the Academy: the symphonic ode Zuleima (based on a text by Heinrich Heine); the orchestral piece Printemps; the cantata La Damoiselle élue (1887–1888), the first piece in which the stylistic features of his later music began to emerge; and the Fantaisie for piano and orchestra, which was heavily based on Franck's music and was eventually withdrawn by Debussy. The Academy chided him for writing music that was "bizarre, incomprehensible and unperformable". Although Debussy's works showed the influence of Jules Massenet, the latter concluded, "He is an enigma". During his years in Rome Debussy composed – not for the Academy – most of his Verlaine cycle, Ariettes oubliées, which made little impact at the time but was successfully republished in 1903 after the composer had become well known.
A week after his return to Paris in 1887, Debussy heard the first act of Wagner's Tristan und Isolde at the Concerts Lamoureux, and judged it "decidedly the finest thing I know". In 1888 and 1889 he went to the annual festivals of Wagner's operas at Bayreuth. He responded positively to Wagner's sensuousness, mastery of form, and striking harmonies, and was briefly influenced by them, but, unlike some other French composers of his generation, he concluded that there was no future in attempting to adopt and develop Wagner's style. He commented in 1903 that Wagner was "a beautiful sunset that was mistaken for a dawn".
In 1889, at the Paris Exposition Universelle, Debussy first heard Javanese gamelan music. The gamelan scales, melodies, rhythms, and ensemble textures appealed to him, and echoes of them are heard in "Pagodes" in his piano suite Estampes. He also attended two concerts of Rimsky-Korsakov's music, conducted by the composer. This too made an impression on him, and its harmonic freedom and non-Teutonic tone colours influenced his own developing musical style.
Marie Vasnier ended her liaison with Debussy soon after his final return from Rome, although they remained on good enough terms for him to dedicate to her one more song, "Mandoline", in 1890. Later in 1890 Debussy met Erik Satie, who proved a kindred spirit in his experimental approach to composition. Both were bohemians, enjoying the same café society and struggling to survive financially. In the same year Debussy began a relationship with Gabrielle (Gaby) Dupont, a tailor's daughter from Lisieux; in July 1893 they began living together.
Debussy continued to compose songs, piano pieces and other works, some of which were publicly performed, but his music made only a modest impact, although his fellow composers recognised his potential by electing him to the committee of the Société Nationale de Musique in 1893. His String Quartet was premiered by the Ysaÿe string quartet at the Société Nationale in the same year. In May 1893 Debussy attended a theatrical event that was of key importance to his later career – the premiere of Maurice Maeterlinck's play Pelléas et Mélisande, which he immediately determined to turn into an opera. He travelled to Maeterlinck's home in Ghent in November to secure his consent to an operatic adaptation.
In February 1894 Debussy completed the first draft of Act I of his operatic version of Pelléas et Mélisande, and for most of the year worked to complete the work. While still living with Dupont, he had an affair with the singer Thérèse Roger, and in 1894 he announced their engagement. His behaviour was widely condemned; anonymous letters circulated denouncing his treatment of both women, as well as his financial irresponsibility and debts. The engagement was broken off, and several of Debussy's friends and supporters disowned him, including Ernest Chausson, hitherto one of his strongest supporters.
In terms of musical recognition, Debussy made a step forward in December 1894, when the symphonic poem Prélude à l'après-midi d'un faune, based on Stéphane Mallarmé's poem, was premiered at a concert of the Société Nationale. The following year he completed the first draft of Pelléas and began efforts to get it staged. In May 1898 he made his first contacts with André Messager and Albert Carré, respectively the musical director and general manager of the Opéra-Comique, Paris, about presenting the opera.
Debussy abandoned Dupont for her friend Marie-Rosalie Texier, known as "Lilly", whom he married in October 1899, after threatening suicide if she refused him. She was affectionate, practical, straightforward, and well liked by Debussy's friends and associates, but he became increasingly irritated by her intellectual limitations and lack of musical sensitivity. The marriage lasted barely five years.
From around 1900 Debussy's music became a focus and inspiration for an informal group of innovative young artists, poets, critics, and musicians who began meeting in Paris. They called themselves Les Apaches – roughly "The Hooligans" – to represent their status as "artistic outcasts". The membership was fluid, but at various times included Maurice Ravel, Ricardo Viñes, Igor Stravinsky and Manuel de Falla. In the same year the first two of Debussy's three orchestral Nocturnes were first performed. Although they did not make any great impact with the public they were well reviewed by musicians including Paul Dukas, Alfred Bruneau and Pierre de Bréville. The complete set was given the following year.
Like many other composers of the time, Debussy supplemented his income by teaching and writing. For most of 1901 he had a sideline as music critic of La Revue Blanche, adopting the pen name "Monsieur Croche". He expressed trenchant views on composers ("I hate sentimentality – his name is Camille Saint-Saëns"), institutions (on the Paris Opéra: "A stranger would take it for a railway station, and, once inside, would mistake it for a Turkish bath"), conductors ("Nikisch is a unique virtuoso, so much so that his virtuosity seems to make him forget the claims of good taste"), musical politics ("The English actually think that a musician can manage an opera house successfully!"), and audiences ("their almost drugged expression of boredom, indifference and even stupidity"). He later collected his criticisms with a view to their publication as a book; it was published after his death as Monsieur Croche, Antidilettante.
In January 1902 rehearsals began at the Opéra-Comique for the opening of Pelléas et Mélisande. For three months, Debussy attended rehearsals practically every day. In February there was conflict between Maeterlinck on the one hand and Debussy, Messager and Carré on the other about the casting of Mélisande. Maeterlinck wanted his mistress, Georgette Leblanc, to sing the role, and was incensed when she was passed over in favour of the Scottish soprano Mary Garden. The opera opened on 30 April 1902, and although the first-night audience was divided between admirers and sceptics, the work quickly became a success. It made Debussy a well-known name in France and abroad; The Times commented that the opera had "provoked more discussion than any work of modern times, excepting, of course, those of Richard Strauss". The Apaches, led by Ravel (who attended every one of the 14 performances in the first run), were loud in their support; the conservative faculty of the Conservatoire tried in vain to stop its students from seeing the opera. The vocal score was published in early May, and the full orchestral score in 1904.
In 1903 there was public recognition of Debussy's stature when he was appointed a Chevalier of the Légion d'honneur, but his social standing suffered a great blow when another turn in his private life caused a scandal the following year. One of his pupils was Raoul Bardac, son of Emma and her husband, Parisian banker Sigismond Bardac. Raoul introduced his teacher to his mother, to whom Debussy quickly became greatly attracted. She was sophisticated, a brilliant conversationalist, an accomplished singer, and relaxed about marital fidelity, having been the mistress and muse of Gabriel Fauré a few years earlier. After despatching Lilly to her parental home at Bichain in Villeneuve-la-Guyard on 15 July 1904, Debussy took Emma away, staying incognito in Jersey and then at Pourville in Normandy. He wrote to his wife on 11 August from Dieppe, telling her that their marriage was over, but still making no mention of Bardac. When he returned to Paris he set up home on his own, taking a flat in a different arrondissement. On 14 October, five days before their fifth wedding anniversary, Lilly Debussy attempted suicide, shooting herself in the chest with a revolver; she survived, although the bullet remained lodged in her vertebrae for the rest of her life. The ensuing scandal caused Bardac's family to disown her, and Debussy lost many good friends including Dukas and Messager. His relations with Ravel, never close, were exacerbated when the latter joined other former friends of Debussy in contributing to a fund to support the deserted Lilly.
The Bardacs divorced in May 1905. Finding the hostility in Paris intolerable, Debussy and Emma (now pregnant) went to England. They stayed at the Grand Hotel, Eastbourne in July and August, where Debussy corrected the proofs of his symphonic sketches La mer, celebrating his divorce on 2 August. After a brief visit to London, the couple returned to Paris in September, buying a house in a courtyard development off the Avenue du Bois de Boulogne (now Avenue Foch), Debussy's home for the rest of his life.
In October 1905 La mer, Debussy's most substantial orchestral work, was premiered in Paris by the Orchestre Lamoureux under the direction of Camille Chevillard; the reception was mixed. Some praised the work, but Pierre Lalo, critic of Le Temps, hitherto an admirer of Debussy, wrote, "I do not hear, I do not see, I do not smell the sea". In the same month the composer's only child was born at their home. Claude-Emma, affectionately known as "Chouchou", was a musical inspiration to the composer (she was the dedicatee of his Children's Corner suite). She outlived her father by scarcely a year, succumbing to the diphtheria epidemic of 1919. Mary Garden said, "I honestly don't know if Debussy ever loved anybody really. He loved his music – and perhaps himself. I think he was wrapped up in his genius", but biographers are agreed that whatever his relations with lovers and friends, Debussy was devoted to his daughter.
Debussy and Emma Bardac eventually married in 1908, their troubled union enduring for the rest of his life. The following year began well, when at Fauré's invitation, Debussy became a member of the governing council of the Conservatoire. His success in London was consolidated in April 1909, when he conducted Prélude à l'après-midi d'un faune and the Nocturnes at the Queen's Hall; in May he was present at the first London production of Pelléas et Mélisande, at Covent Garden. In the same year, Debussy was diagnosed with colorectal cancer, from which he was to die nine years later.
Debussy's works began to feature increasingly in concert programmes at home and overseas. In 1910 Gustav Mahler conducted the Nocturnes and Prélude à l'après-midi d'un faune in New York in successive months. In the same year, visiting Budapest, Debussy commented that his works were better known there than in Paris. In 1912 Sergei Diaghilev commissioned a new ballet score, Jeux. That, and the three Images, premiered the following year, were the composer's last orchestral works. Jeux was unfortunate in its timing: two weeks after the premiere, in March 1913, Diaghilev presented the first performance of Stravinsky's The Rite of Spring, a sensational event that monopolised discussion in musical circles, and effectively sidelined Jeux along with Fauré's Pénélope, which had opened a week before.
In 1915 Debussy underwent one of the earliest colostomy operations. It achieved only a temporary respite, and occasioned him considerable frustration ("There are mornings when the effort of dressing seems like one of the twelve labours of Hercules"). He also had a fierce enemy at this period in the form of Camille Saint-Saëns, who in a letter to Fauré condemned Debussy's En blanc et noir: "It's incredible, and the door of the Institut [de France] must at all costs be barred against a man capable of such atrocities". Saint-Saëns had been a member of the Institut since 1881: Debussy never became one. His health continued to decline; he gave his final concert on 14 September 1917 and became bedridden in early 1918.
Debussy died on 25 March 1918 at his home. The First World War was still raging and Paris was under German aerial and artillery bombardment. The military situation did not permit the honour of a public funeral with ceremonious graveside orations. The funeral procession made its way through deserted streets to a temporary grave at Père Lachaise Cemetery as the German guns bombarded the city. Debussy's body was reinterred the following year in the small Passy Cemetery sequestered behind the Trocadéro, fulfilling his wish to rest "among the trees and the birds"; his wife and daughter are buried with him.
In a survey of Debussy's oeuvre shortly after the composer's death, the critic Ernest Newman wrote, "It would be hardly too much to say that Debussy spent a third of his life in the discovery of himself, a third in the free and happy realisation of himself, and the final third in the partial, painful loss of himself". Later commentators have rated some of the late works more highly than Newman and other contemporaries did, but much of the music for which Debussy is best known is from the middle years of his career.
The analyst David Cox wrote in 1974 that Debussy, admiring Wagner's attempts to combine all the creative arts, "created a new, instinctive, dreamlike world of music, lyrical and pantheistic, contemplative and objective – a kind of art, in fact, which seemed to reach out into all aspects of experience". In 1988 the composer and scholar Wilfrid Mellers wrote of Debussy:
Because of, rather than in spite of, his preoccupation with chords in themselves, he deprived music of the sense of harmonic progression, broke down three centuries' dominance of harmonic tonality, and showed how the melodic conceptions of tonality typical of primitive folk-music and of medieval music might be relevant to the twentieth century
Debussy did not give his works opus numbers, apart from his String Quartet, Op. 10 in G minor (also the only work where the composer's title included a key). His works were catalogued and indexed by the musicologist François Lesure in 1977 (revised in 2003) and their Lesure number ("L" followed by a number) is sometimes used as a suffix to their title in concert programmes and recordings.
Debussy's musical development was slow, and as a student he was adept enough to produce for his teachers at the Conservatoire works that would conform to their conservative precepts. His friend Georges Jean-Aubry commented that Debussy "admirably imitated Massenet's melodic turns of phrase" in the cantata L'enfant prodigue (1884) which won him the Prix de Rome. A more characteristically Debussian work from his early years is La Damoiselle élue, recasting the traditional form for oratorios and cantatas, using a chamber orchestra and a small body of choral tone and using new or long-neglected scales and harmonies. His early mélodies, inspired by Marie Vasnier, are more virtuosic in character than his later works in the genre, with extensive wordless vocalise; from the Ariettes oubliées (1885–1887) onwards he developed a more restrained style. He wrote his own poems for the Proses lyriques (1892–1893) but, in the view of the musical scholar Robert Orledge, "his literary talents were not on a par with his musical imagination".
The musicologist Jacques-Gabriel Prod'homme wrote that, together with La Demoiselle élue, the Ariettes oubliées and the Cinq poèmes de Charles Baudelaire (1889) show "the new, strange way which the young musician will hereafter follow". Newman concurred: "There is a good deal of Wagner, especially of Tristan, in the idiom. But the work as a whole is distinctive, and the first in which we get a hint of the Debussy we were to know later – the lover of vague outlines, of half-lights, of mysterious consonances and dissonances of colour, the apostle of languor, the exclusivist in thought and in style." During the next few years Debussy developed his personal style, without, at this stage, breaking sharply away from French musical traditions. Much of his music from this period is on a small scale, such as the Two Arabesques, Valse romantique, Suite bergamasque, and the first set of Fêtes galantes. Newman remarked that, like Chopin, the Debussy of this period appears as a liberator from Germanic styles of composition – offering instead "an exquisite, pellucid style" capable of conveying "not only gaiety and whimsicality but emotion of a deeper sort". In a 2004 study, Mark DeVoto comments that Debussy's early works are harmonically no more adventurous than existing music by Fauré; in a 2007 book about the piano works, Margery Halford observes that Two Arabesques (1888–1891) and "Rêverie" (1890) have "the fluidity and warmth of Debussy's later style" but are not harmonically innovative. Halford cites the popular "Clair de Lune" (1890), the third of the four movements of Suite Bergamasque, as a transitional work pointing towards the composer's mature style.
Musicians from Debussy's time onwards have regarded Prélude à l'après-midi d'un faune (1894) as his first orchestral masterpiece. Newman considered it "completely original in idea, absolutely personal in style, and logical and coherent from first to last, without a superfluous bar or even a superfluous note"; Pierre Boulez observed, "Modern music was awakened by Prélude à l'après-midi d'un faune". Most of the major works for which Debussy is best known were written between the mid-1890s and the mid-1900s. They include the String Quartet (1893), Pelléas et Mélisande (1893–1902), the Nocturnes for Orchestra (1899) and La mer (1903–1905). The suite Pour le piano (1894–1901) is, in Halford's view, one of the first examples of the mature Debussy as a composer for the piano: "a major landmark ... and an enlargement of the use of piano sonorities".
In the String Quartet (1893), the gamelan sonorities Debussy had heard four years earlier are recalled in the pizzicatos and cross-rhythms of the scherzo. Debussy's biographer Edward Lockspeiser comments that this movement shows the composer's rejection of "the traditional dictum that string instruments should be predominantly lyrical". The work influenced Ravel, whose own String Quartet, written ten years later, has noticeably Debussian features. The academic and journalist Stephen Walsh calls Pelléas et Mélisande (begun 1893, staged 1902) "a key work for the 20th century". The composer Olivier Messiaen was fascinated by its "extraordinary harmonic qualities and ... transparent instrumental texture". The opera is composed in what Alan Blyth describes as a sustained and heightened recitative style, with "sensuous, intimate" vocal lines. It influenced composers as different as Stravinsky and Puccini.
Orledge describes the Nocturnes as exceptionally varied in texture, "ranging from the Musorgskian start of 'Nuages', through the approaching brass band procession in 'Fêtes', to the wordless female chorus in 'Sirènes'". Orledge considers the last a pre-echo of the marine textures of La mer. Estampes for piano (1903) gives impressions of exotic locations, with further echoes of the gamelan in its pentatonic structures. Debussy believed that since Beethoven, the traditional symphonic form had become formulaic, repetitive and obsolete. The three-part, cyclic symphony by César Franck (1888) was more to his liking, and its influence can be found in La mer (1905); this uses a quasi-symphonic form, its three sections making up a giant sonata-form movement with, as Orledge observes, a cyclic theme, in the manner of Franck. The central "Jeux de vagues" section has the function of a symphonic development section leading into the final "Dialogue du vent et de la mer", "a powerful essay in orchestral colour and sonority" (Orledge) which reworks themes from the first movement. The reviews were sharply divided. Some critics thought the treatment less subtle and less mysterious than his previous works, and even a step backward; others praised its "power and charm", its "extraordinary verve and brilliant fantasy", and its strong colours and definite lines.
Of the later orchestral works, Images (1905–1912) is better known than Jeux (1913). The former follows the tripartite form established in the Nocturnes and La mer, but differs in employing traditional British and French folk tunes, and in making the central movement, "Ibéria", far longer than the outer ones, and subdividing it into three parts, all inspired by scenes from Spanish life. Although considering Images "the pinnacle of Debussy's achievement as a composer for orchestra", Trezise notes a contrary view that the accolade belongs to the ballet score Jeux. The latter failed as a ballet because of what Jann Pasler describes as a banal scenario, and the score was neglected for some years. Recent analysts have found it a link between traditional continuity and thematic growth within a score and the desire to create discontinuity in a way mirrored in later 20th century music. In this piece, Debussy abandoned the whole-tone scale he had often favoured previously in favour of the octatonic scale with what the Debussy scholar François Lesure describes as its tonal ambiguities.
Among the late piano works are two books of Préludes (1909–10, 1911–13), short pieces that depict a wide range of subjects. Lesure comments that they range from the frolics of minstrels at Eastbourne in 1905 and the American acrobat "General Lavine" "to dead leaves and the sounds and scents of the evening air". En blanc et noir (In white and black, 1915), a three-movement work for two pianos, is a predominantly sombre piece, reflecting the war and national danger. The Études (1915) for piano have divided opinion. Writing soon after Debussy's death, Newman found them laboured – "a strange last chapter in a great artist's life"; Lesure, writing eighty years later, rates them among Debussy's greatest late works: "Behind a pedagogic exterior, these 12 pieces explore abstract intervals, or – in the last five – the sonorities and timbres peculiar to the piano." In 1914 Debussy started work on a planned set of six sonatas for various instruments. His fatal illness prevented him from completing the set, but those for cello and piano (1915), flute, viola and harp (1915), and violin and piano (1917 – his last completed work) are all concise, three-movement pieces, more diatonic in nature than some of his other late works.
Le Martyre de saint Sébastien (1911), originally a five-act musical play to a text by Gabriele D'Annunzio that took nearly five hours in performance, was not a success, and the music is now more often heard in a concert (or studio) adaptation with narrator, or as an orchestral suite of "Fragments symphoniques". Debussy enlisted the help of André Caplet in orchestrating and arranging the score. Two late stage works, the ballets Khamma (1912) and La boîte à joujoux (1913), were left with the orchestration incomplete, and were completed by Charles Koechlin and Caplet, respectively.
The application of the term "Impressionist" to Debussy and the music he influenced has been much debated, both during his lifetime and since. The analyst Richard Langham Smith writes that Impressionism was originally a term coined to describe a style of late 19th-century French painting, typically scenes suffused with reflected light in which the emphasis is on the overall impression rather than outline or clarity of detail, as in works by Monet, Pissarro, Renoir and others. Langham Smith writes that the term became transferred to the compositions of Debussy and others which were "concerned with the representation of landscape or natural phenomena, particularly the water and light imagery dear to Impressionists, through subtle textures suffused with instrumental colour".
Among painters, Debussy particularly admired Turner, but also drew inspiration from Whistler. With the latter in mind the composer wrote to the violinist Eugène Ysaÿe in 1894 describing the orchestral Nocturnes as "an experiment in the different combinations that can be obtained from one colour – what a study in grey would be in painting."
Debussy strongly objected to the use of the word "Impressionism" for his (or anybody else's) music, but it has continually been attached to him since the assessors at the Conservatoire first applied it, opprobriously, to his early work Printemps. Langham Smith comments that Debussy wrote many piano pieces with titles evocative of nature – "Reflets dans l'eau" (1905), "Les Sons et les parfums tournent dans l'air du soir" (1910) and "Brouillards" (1913) – and suggests that the Impressionist painters' use of brush-strokes and dots is paralleled in the music of Debussy. Although Debussy said that anyone using the term (whether about painting or music) was an imbecile, some Debussy scholars have taken a less absolutist line. Lockspeiser calls La mer "the greatest example of an orchestral Impressionist work", and more recently in The Cambridge Companion to Debussy Nigel Simeone comments, "It does not seem unduly far-fetched to see a parallel in Monet's seascapes".
In this context may be placed Debussy's pantheistic eulogy to Nature, in a 1911 interview with Henry Malherbe:
I have made mysterious Nature my religion ... When I gaze at a sunset sky and spend hours contemplating its marvellous ever-changing beauty, an extraordinary emotion overwhelms me. Nature in all its vastness is truthfully reflected in my sincere though feeble soul. Around me are the trees stretching up their branches to the skies, the perfumed flowers gladdening the meadow, the gentle grass-carpeted earth, ... and my hands unconsciously assume an attitude of adoration.
In contrast to the "impressionistic" characterisation of Debussy's music, several writers have suggested that he structured at least some of his music on rigorous mathematical lines. In 1983 the pianist and scholar Roy Howat published a book contending that certain of Debussy's works are proportioned using mathematical models, even while using an apparent classical structure such as sonata form. Howat suggests that some of Debussy's pieces can be divided into sections that reflect the golden ratio, which is approximated by ratios of consecutive numbers in the Fibonacci sequence. Simon Trezise, in his 1994 book Debussy: La Mer, finds the intrinsic evidence "remarkable", with the caveat that no written or reported evidence suggests that Debussy deliberately sought such proportions. Lesure takes a similar view, endorsing Howat's conclusions while not taking a view on Debussy's conscious intentions.
Debussy wrote "We must agree that the beauty of a work of art will always remain a mystery [...] we can never be absolutely sure 'how it's made.' We must at all costs preserve this magic which is peculiar to music and to which music, by its nature, is of all the arts the most receptive."
Nevertheless, there are many indicators of the sources and elements of Debussy's idiom. Writing in 1958, the critic Rudolph Reti summarised six features of Debussy's music, which he asserted "established a new concept of tonality in European music": the frequent use of lengthy pedal points – "not merely bass pedals in the actual sense of the term, but sustained 'pedals' in any voice"; glittering passages and webs of figurations which distract from occasional absence of tonality; frequent use of parallel chords which are "in essence not harmonies at all, but rather 'chordal melodies', enriched unisons", described by some writers as non-functional harmonies; bitonality, or at least bitonal chords; use of the whole-tone and pentatonic scales; and unprepared modulations, "without any harmonic bridge". Reti concludes that Debussy's achievement was the synthesis of monophonic based "melodic tonality" with harmonies, albeit different from those of "harmonic tonality".
In 1889, Debussy held conversations with his former teacher Guiraud, which included exploration of harmonic possibilities at the piano. The discussion, and Debussy's chordal keyboard improvisations, were noted by a younger pupil of Guiraud, Maurice Emmanuel. The chord sequences played by Debussy include some of the elements identified by Reti. They may also indicate the influence on Debussy of Satie's 1887 Trois Sarabandes. A further improvisation by Debussy during this conversation included a sequence of whole tone harmonies which may have been inspired by the music of Glinka or Rimsky-Korsakov which was becoming known in Paris at this time. During the conversation, Debussy told Guiraud, "There is no theory. You have only to listen. Pleasure is the law!" – although he also conceded, "I feel free because I have been through the mill, and I don't write in the fugal style because I know it."
"Chabrier, Moussorgsky, Palestrina, voilà ce que j'aime" – they are what I love.
Debussy in 1893
Among French predecessors, Chabrier was an important influence on Debussy (as he was on Ravel and Poulenc); Howat has written that Chabrier's piano music such as "Sous-bois" and "Mauresque" in the Pièces pittoresques explored new sound-worlds of which Debussy made effective use 30 years later. Lesure finds traces of Gounod and Massenet in some of Debussy's early songs, and remarks that it may have been from the Russians – Tchaikovsky, Balakirev, Rimsky-Korsakov, Borodin and Mussorgsky – that Debussy acquired his taste for "ancient and oriental modes and for vivid colorations, and a certain disdain for academic rules". Lesure also considers that Mussorgsky's opera Boris Godunov directly influenced Debussy's Pelléas et Mélisande. In the music of Palestrina, Debussy found what he called "a perfect whiteness", and he felt that although Palestrina's musical forms had a "strict manner", they were more to his taste than the rigid rules prevailing among 19th-century French composers and teachers. He drew inspiration from what he called Palestrina's "harmony created by melody", finding an arabesque-like quality in the melodic lines.
Debussy opined that Chopin was "the greatest of them all, for through the piano he discovered everything"; he professed his "respectful gratitude" for Chopin's piano music. He was torn between dedicating his own Études to Chopin or to François Couperin, whom he also admired as a model of form, seeing himself as heir to their mastery of the genre. Howat cautions against the assumption that Debussy's Ballade (1891) and Nocturne (1892) are influenced by Chopin – in Howat's view they owe more to Debussy's early Russian models – but Chopin's influence is found in other early works such as the Two arabesques (1889–1891). In 1914 the publisher A. Durand & fils began publishing scholarly new editions of the works of major composers, and Debussy undertook the supervision of the editing of Chopin's music.
Although Debussy was in no doubt of Wagner's stature, he was only briefly influenced by him in his compositions, after La damoiselle élue and the Cinq poèmes de Baudelaire (both begun in 1887). According to Pierre Louÿs, Debussy "did not see 'what anyone can do beyond Tristan'," although he admitted that it was sometimes difficult to avoid "the ghost of old Klingsor, alias Richard Wagner, appearing at the turning of a bar". After Debussy's short Wagnerian phase, he started to become interested in non-Western music and its unfamiliar approaches to composition. The piano piece Golliwogg's Cakewalk, from the 1908 suite Children's Corner, contains a parody of music from the introduction to Tristan, in which, in the opinion of the musicologist Lawrence Kramer, Debussy escapes the shadow of the older composer and "smilingly relativizes Wagner into insignificance".
A contemporary influence was Erik Satie, according to Nichols Debussy's "most faithful friend" amongst French musicians. Debussy's orchestration in 1896 of Satie's Gymnopédies (which had been written in 1887) "put their composer on the map" according to the musicologist Richard Taruskin, and the Sarabande from Debussy's Pour le piano (1901) "shows that [Debussy] knew Satie's Trois Sarabandes at a time when only a personal friend of the composer could have known them." (They were not published until 1911). Debussy's interest in the popular music of his time is evidenced not only by the Golliwogg's Cakewalk and other piano pieces featuring rag-time, such as The Little Nigar (Debussy's spelling) (1909), but by the slow waltz La plus que lente (The more than slow), based on the style of the gipsy violinist at a Paris hotel (to whom he gave the manuscript of the piece).
In addition to the composers who influenced his own compositions, Debussy held strong views about several others. He was for the most part enthusiastic about Richard Strauss and Stravinsky, respectful of Mozart and was in awe of Bach, whom he called the "good God of music" (le Bon Dieu de la musique). His relationship to Beethoven was complex; he was said to refer to him as le vieux sourd ('the old deaf one') and asked one young pupil not to play Beethoven's music for "it is like somebody dancing on my grave;" but he believed that Beethoven had profound things to say, yet did not know how to say them, "because he was imprisoned in a web of incessant restatement and of German aggressiveness." He was not in sympathy with Schubert, Schumann, Brahms and Mendelssohn, the latter being described as a "facile and elegant notary".
With the advent of the First World War, Debussy became ardently patriotic in his musical opinions. Writing to Stravinsky, he asked "How could we not have foreseen that these men were plotting the destruction of our art, just as they had planned the destruction of our country?" In 1915 he complained that "since Rameau we have had no purely French tradition [...] We tolerated overblown orchestras, tortuous forms [...] we were about to give the seal of approval to even more suspect naturalizations when the sound of gunfire put a sudden stop to it all." Taruskin writes that some have seen this as a reference to the composers Gustav Mahler and Arnold Schoenberg, both born Jewish. In 1912 Debussy had remarked to his publisher of the opera Ariane et Barbe-bleue by the (also Jewish) composer Paul Dukas, "You're right, [it] is a masterpiece – but it's not a masterpiece of French music."
Despite his lack of formal schooling, Debussy read widely and found inspiration in literature. Lesure writes, "The development of free verse in poetry and the disappearance of the subject or model in painting influenced him to think about issues of musical form." Debussy was influenced by the Symbolist poets. These writers, who included Verlaine, Mallarmé, Maeterlinck and Rimbaud, reacted against the realism, naturalism, objectivity and formal conservatism that prevailed in the 1870s. They favoured poetry using suggestion rather than direct statement; the literary scholar Chris Baldrick writes that they evoked "subjective moods through the use of private symbols, while avoiding the description of external reality or the expression of opinion". Debussy was much in sympathy with the Symbolists' desire to bring poetry closer to music, became friendly with several leading exponents, and set many Symbolist works throughout his career.
Debussy's literary inspirations were mostly French, but he did not overlook foreign writers. As well as Maeterlinck for Pelléas et Mélisande, he drew on Shakespeare and Dickens for two of his Préludes for piano – La Danse de Puck (Book 1, 1910) and Hommage à S. Pickwick Esq. P.P.M.P.C. (Book 2, 1913). He set Dante Gabriel Rossetti's The Blessed Damozel in his early cantata, La Damoiselle élue (1888). He wrote incidental music for King Lear and planned an opera based on As You Like It, but abandoned that once he turned his attention to setting Maeterlinck's play. In 1890 he began work on an orchestral piece inspired by Edgar Allan Poe's The Fall of the House of Usher and later sketched the libretto for an opera, La chute de la maison Usher. Another project inspired by Poe – an operatic version of The Devil in the Belfry did not progress beyond sketches. French writers whose words he set include Paul Bourget, Alfred de Musset, Théodore de Banville, Leconte de Lisle, Théophile Gautier, Paul Verlaine, François Villon, and Mallarmé – the last of whom also provided Debussy with the inspiration for one of his most popular orchestral pieces, Prélude à l'après-midi d'un faune.
Debussy is widely regarded as one of the most influential composers of the 20th century. Roger Nichols writes that "if one omits Schoenberg [...] a list of 20th-century composers influenced by Debussy is practically a list of 20th-century composers tout court."
Bartók first encountered Debussy's music in 1907 and later said that "Debussy's great service to music was to reawaken among all musicians an awareness of harmony and its possibilities". Not only Debussy's use of whole-tone scales, but also his style of word-setting in Pelléas et Mélisande, were the subject of study by Leoš Janáček while he was writing his 1921 opera Káťa Kabanová. Stravinsky was more ambivalent about Debussy's music (he thought Pelléas "a terrible bore ... in spite of many wonderful pages") but the two composers knew each other and Stravinsky's Symphonies of Wind Instruments (1920) was written as a memorial for Debussy.
In the aftermath of the First World War, the young French composers of Les Six reacted against what they saw as the poetic, mystical quality of Debussy's music in favour of something more hard-edged. Their sympathiser and self-appointed spokesman Jean Cocteau wrote in 1918: "Enough of nuages, waves, aquariums, ondines and nocturnal perfumes," pointedly alluding to the titles of pieces by Debussy. Later generations of French composers had a much more positive relationship with his music. Messiaen was given a score of Pelléas et Mélisande as a boy and said that it was "a revelation, love at first sight" and "probably the most decisive influence I have been subject to". Boulez also discovered Debussy's music at a young age and said that it gave him his first sense of what modernity in music could mean.
Among contemporary composers George Benjamin has described Prélude à l'après-midi d'un faune as "the definition of perfection"; he has conducted Pelléas et Mélisande and the critic Rupert Christiansen detects the influence of the work in Benjamin's opera Written on Skin (2012). Others have made orchestrations of some of the piano and vocal works, including John Adams's version of four of the Baudelaire songs (Le Livre de Baudelaire, 1994), Robin Holloway's of En blanc et noir (2002), and Colin Matthews's of both books of Préludes (2001–2006).
The pianist Stephen Hough believes that Debussy's influence also extends to jazz and suggests that Reflets dans l'eau can be heard in the harmonies of Bill Evans.
In 1904, Debussy played the piano accompaniment for Mary Garden in recordings for the Compagnie française du Gramophone of four of his songs: three mélodies from the Verlaine cycle Ariettes oubliées – "Il pleure dans mon coeur", "L'ombre des arbres" and "Green" – and "Mes longs cheveux", from Act III of Pelléas et Mélisande. He made a set of piano rolls for the Welte-Mignon company in 1913. They contain fourteen of his pieces: "D'un cahier d'esquisses", "La plus que lente", "La soirée dans Grenade", all six movements of Children's Corner, and five of the Preludes: "Danseuses de Delphes", "Le vent dans la plaine", "La cathédrale engloutie", "La danse de Puck" and "Minstrels". The 1904 and 1913 sets have been transferred to compact disc.
Contemporaries of Debussy who made recordings of his music included the pianists Ricardo Viñes (in "Poissons d'or" from Images and "La soirée dans Grenade" from Estampes); Alfred Cortot (numerous solo pieces as well as the Violin Sonata with Jacques Thibaud and the Chansons de Bilitis with Maggie Teyte); and Marguerite Long ("Jardins sous la pluie" and "Arabesques"). Singers in Debussy's mélodies or excerpts from Pelléas et Mélisande included Jane Bathori, Claire Croiza, Charles Panzéra and Ninon Vallin; and among the conductors in the major orchestral works were Ernest Ansermet, Désiré-Émile Inghelbrecht, Pierre Monteux and Arturo Toscanini, and in the Petite Suite, Henri Büsser, who had prepared the orchestration for Debussy. Many of these early recordings have been reissued on CD.
In more recent times Debussy's output has been extensively recorded. In 2018, to mark the centenary of the composer's death, Warner Classics, with contributions from other companies, issued a 33-CD set that is claimed to include all the music Debussy wrote. | [
{
"paragraph_id": 0,
"text": "(Achille) Claude Debussy (French: [aʃil klod dəbysi]; 22 August 1862 – 25 March 1918) was a French composer. He is sometimes seen as the first Impressionist composer, although he vigorously rejected the term. He was among the most influential composers of the late 19th and early 20th centuries.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Born to a family of modest means and little cultural involvement, Debussy showed enough musical talent to be admitted at the age of ten to France's leading music college, the Conservatoire de Paris. He originally studied the piano, but found his vocation in innovative composition, despite the disapproval of the Conservatoire's conservative professors. He took many years to develop his mature style, and was nearly 40 when he achieved international fame in 1902 with the only opera he completed, Pelléas et Mélisande.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Debussy's orchestral works include Prélude à l'après-midi d'un faune (1894), Nocturnes (1897–1899) and Images (1905–1912). His music was to a considerable extent a reaction against Wagner and the German musical tradition. He regarded the classical symphony as obsolete and sought an alternative in his \"symphonic sketches\", La mer (1903–1905). His piano works include sets of 24 Préludes and 12 Études. Throughout his career he wrote mélodies based on a wide variety of poetry, including his own. He was greatly influenced by the Symbolist poetic movement of the later 19th century. A small number of works, including the early La Damoiselle élue and the late Le Martyre de saint Sébastien have important parts for chorus. In his final years, he focused on chamber music, completing three of six planned sonatas for different combinations of instruments.",
"title": ""
},
{
"paragraph_id": 3,
"text": "With early influences including Russian and Far Eastern music and works by Chopin, Debussy developed his own style of harmony and orchestral colouring, derided – and unsuccessfully resisted – by much of the musical establishment of the day. His works have strongly influenced a wide range of composers including Béla Bartók, Olivier Messiaen, George Benjamin, and the jazz pianist and composer Bill Evans. Debussy died from cancer at his home in Paris at the age of 55 after a composing career of a little more than 30 years.",
"title": ""
},
{
"paragraph_id": 4,
"text": "Debussy was born on 22 August 1862 in Saint-Germain-en-Laye, Seine-et-Oise, on the north-west fringes of Paris. He was the eldest of the five children of Manuel-Achille Debussy and his wife, Victorine, née Manoury. Debussy senior ran a china shop and his wife was a seamstress. The shop was unsuccessful, and closed in 1864; the family moved to Paris, first living with Victorine's mother, in Clichy, and, from 1868, in their own apartment in the Rue Saint-Honoré. Manuel worked in a printing factory.",
"title": "Life and career"
},
{
"paragraph_id": 5,
"text": "In 1870, to escape the siege of Paris during the Franco-Prussian War, Debussy's pregnant mother took him and his sister Adèle to their paternal aunt's home in Cannes, where they remained until the following year. During his stay in Cannes, the seven-year-old Debussy had his first piano lessons; his aunt paid for him to study with an Italian musician, Jean Cerutti. Manuel Debussy remained in Paris and joined the forces of the Commune; after its defeat by French government troops in 1871 he was sentenced to four years' imprisonment, of which he only served one year. His fellow Communard prisoners included his friend Charles de Sivry, a musician. Sivry's mother, Antoinette Mauté de Fleurville, gave piano lessons, and at his instigation the young Debussy became one of her pupils.",
"title": "Life and career"
},
{
"paragraph_id": 6,
"text": "Debussy's talents soon became evident, and in 1872, aged ten, he was admitted to the Conservatoire de Paris, where he remained a student for the next eleven years. He first joined the piano class of Antoine François Marmontel, and studied solfège with Albert Lavignac and, later, composition with Ernest Guiraud, harmony with Émile Durand, and organ with César Franck. The course included music history and theory studies with Louis-Albert Bourgault-Ducoudray, but it is not certain that Debussy, who was apt to skip classes, actually attended these.",
"title": "Life and career"
},
{
"paragraph_id": 7,
"text": "At the Conservatoire, Debussy initially made good progress. Marmontel said of him, \"A charming child, a truly artistic temperament; much can be expected of him\". Another teacher was less impressed: Émile Durand wrote in a report, \"Debussy would be an excellent pupil if he were less sketchy and less cavalier.\" A year later he described Debussy as \"desperately careless\". In July 1874 Debussy received the award of deuxième accessit for his performance as soloist in the first movement of Chopin's Second Piano Concerto at the Conservatoire's annual competition. He was a fine pianist and an outstanding sight reader, who could have had a professional career had he wished, but he was only intermittently diligent in his studies. He advanced to premier accessit in 1875 and second prize in 1877, but failed at the competitions in 1878 and 1879. These failures made him ineligible to continue in the Conservatoire's piano classes, but he remained a student for harmony, solfège and, later, composition.",
"title": "Life and career"
},
{
"paragraph_id": 8,
"text": "With Marmontel's help Debussy secured a summer vacation job in 1879 as resident pianist at the Château de Chenonceau, where he rapidly acquired a taste for luxury that was to remain with him all his life. His first compositions date from this period, two settings of poems by Alfred de Musset: \"Ballade à la lune\" and \"Madrid, princesse des Espagnes\". The following year he secured a job as pianist in the household of Nadezhda von Meck, the patroness of Tchaikovsky. He travelled with her family for the summers of 1880 to 1882, staying at various places in France, Switzerland and Italy, as well as at her home in Moscow. He composed his Piano Trio in G major for von Meck's ensemble, and made a transcription for piano duet of three dances from Tchaikovsky's Swan Lake.",
"title": "Life and career"
},
{
"paragraph_id": 9,
"text": "At the end of 1880 Debussy, while continuing his studies at the Conservatoire, was engaged as accompanist for Marie Moreau-Sainti's singing class; he took this role for four years. Among the members of the class was Marie Vasnier; Debussy was greatly taken with her, and she inspired him to compose: he wrote 27 songs dedicated to her during their seven-year relationship. She was the wife of Henri Vasnier, a prominent civil servant, and much younger than her husband. She soon became Debussy's lover as well as his muse. Whether Vasnier was content to tolerate his wife's affair with the young student or was simply unaware of it is not clear, but he and Debussy remained on excellent terms, and he continued to encourage the composer in his career.",
"title": "Life and career"
},
{
"paragraph_id": 10,
"text": "At the Conservatoire, Debussy incurred the disapproval of the faculty, particularly his composition teacher, Guiraud, for his failure to follow the orthodox rules of composition then prevailing. Nevertheless, in 1884 Debussy won France's most prestigious musical award, the Prix de Rome, with his cantata L'enfant prodigue. The Prix carried with it a residence at the Villa Medici, the French Academy in Rome, to further the winner's studies. Debussy was there from January 1885 to March 1887, with three or possibly four absences of several weeks when he returned to France, chiefly to see Marie Vasnier.",
"title": "Life and career"
},
{
"paragraph_id": 11,
"text": "Initially Debussy found the artistic atmosphere of the Villa Medici stifling, the company boorish, the food bad, and the accommodation \"abominable\". Neither did he delight in Italian opera, as he found the operas of Donizetti and Verdi not to his taste. He was much more impressed by the music of the 16th-century composers Palestrina and Lassus, which he heard at Santa Maria dell'Anima: \"The only church music I will accept\". He was often depressed and unable to compose, but he was inspired by Franz Liszt, who visited the students and played for them. In June 1885, Debussy wrote of his desire to follow his own way, saying, \"I am sure the Institute would not approve, for, naturally it regards the path which it ordains as the only right one. But there is no help for it! I am too enamoured of my freedom, too fond of my own ideas!\"",
"title": "Life and career"
},
{
"paragraph_id": 12,
"text": "Debussy finally composed four pieces that were submitted to the Academy: the symphonic ode Zuleima (based on a text by Heinrich Heine); the orchestral piece Printemps; the cantata La Damoiselle élue (1887–1888), the first piece in which the stylistic features of his later music began to emerge; and the Fantaisie for piano and orchestra, which was heavily based on Franck's music and was eventually withdrawn by Debussy. The Academy chided him for writing music that was \"bizarre, incomprehensible and unperformable\". Although Debussy's works showed the influence of Jules Massenet, the latter concluded, \"He is an enigma\". During his years in Rome Debussy composed – not for the Academy – most of his Verlaine cycle, Ariettes oubliées, which made little impact at the time but was successfully republished in 1903 after the composer had become well known.",
"title": "Life and career"
},
{
"paragraph_id": 13,
"text": "A week after his return to Paris in 1887, Debussy heard the first act of Wagner's Tristan und Isolde at the Concerts Lamoureux, and judged it \"decidedly the finest thing I know\". In 1888 and 1889 he went to the annual festivals of Wagner's operas at Bayreuth. He responded positively to Wagner's sensuousness, mastery of form, and striking harmonies, and was briefly influenced by them, but, unlike some other French composers of his generation, he concluded that there was no future in attempting to adopt and develop Wagner's style. He commented in 1903 that Wagner was \"a beautiful sunset that was mistaken for a dawn\".",
"title": "Life and career"
},
{
"paragraph_id": 14,
"text": "In 1889, at the Paris Exposition Universelle, Debussy first heard Javanese gamelan music. The gamelan scales, melodies, rhythms, and ensemble textures appealed to him, and echoes of them are heard in \"Pagodes\" in his piano suite Estampes. He also attended two concerts of Rimsky-Korsakov's music, conducted by the composer. This too made an impression on him, and its harmonic freedom and non-Teutonic tone colours influenced his own developing musical style.",
"title": "Life and career"
},
{
"paragraph_id": 15,
"text": "Marie Vasnier ended her liaison with Debussy soon after his final return from Rome, although they remained on good enough terms for him to dedicate to her one more song, \"Mandoline\", in 1890. Later in 1890 Debussy met Erik Satie, who proved a kindred spirit in his experimental approach to composition. Both were bohemians, enjoying the same café society and struggling to survive financially. In the same year Debussy began a relationship with Gabrielle (Gaby) Dupont, a tailor's daughter from Lisieux; in July 1893 they began living together.",
"title": "Life and career"
},
{
"paragraph_id": 16,
"text": "Debussy continued to compose songs, piano pieces and other works, some of which were publicly performed, but his music made only a modest impact, although his fellow composers recognised his potential by electing him to the committee of the Société Nationale de Musique in 1893. His String Quartet was premiered by the Ysaÿe string quartet at the Société Nationale in the same year. In May 1893 Debussy attended a theatrical event that was of key importance to his later career – the premiere of Maurice Maeterlinck's play Pelléas et Mélisande, which he immediately determined to turn into an opera. He travelled to Maeterlinck's home in Ghent in November to secure his consent to an operatic adaptation.",
"title": "Life and career"
},
{
"paragraph_id": 17,
"text": "In February 1894 Debussy completed the first draft of Act I of his operatic version of Pelléas et Mélisande, and for most of the year worked to complete the work. While still living with Dupont, he had an affair with the singer Thérèse Roger, and in 1894 he announced their engagement. His behaviour was widely condemned; anonymous letters circulated denouncing his treatment of both women, as well as his financial irresponsibility and debts. The engagement was broken off, and several of Debussy's friends and supporters disowned him, including Ernest Chausson, hitherto one of his strongest supporters.",
"title": "Life and career"
},
{
"paragraph_id": 18,
"text": "In terms of musical recognition, Debussy made a step forward in December 1894, when the symphonic poem Prélude à l'après-midi d'un faune, based on Stéphane Mallarmé's poem, was premiered at a concert of the Société Nationale. The following year he completed the first draft of Pelléas and began efforts to get it staged. In May 1898 he made his first contacts with André Messager and Albert Carré, respectively the musical director and general manager of the Opéra-Comique, Paris, about presenting the opera.",
"title": "Life and career"
},
{
"paragraph_id": 19,
"text": "Debussy abandoned Dupont for her friend Marie-Rosalie Texier, known as \"Lilly\", whom he married in October 1899, after threatening suicide if she refused him. She was affectionate, practical, straightforward, and well liked by Debussy's friends and associates, but he became increasingly irritated by her intellectual limitations and lack of musical sensitivity. The marriage lasted barely five years.",
"title": "Life and career"
},
{
"paragraph_id": 20,
"text": "From around 1900 Debussy's music became a focus and inspiration for an informal group of innovative young artists, poets, critics, and musicians who began meeting in Paris. They called themselves Les Apaches – roughly \"The Hooligans\" – to represent their status as \"artistic outcasts\". The membership was fluid, but at various times included Maurice Ravel, Ricardo Viñes, Igor Stravinsky and Manuel de Falla. In the same year the first two of Debussy's three orchestral Nocturnes were first performed. Although they did not make any great impact with the public they were well reviewed by musicians including Paul Dukas, Alfred Bruneau and Pierre de Bréville. The complete set was given the following year.",
"title": "Life and career"
},
{
"paragraph_id": 21,
"text": "Like many other composers of the time, Debussy supplemented his income by teaching and writing. For most of 1901 he had a sideline as music critic of La Revue Blanche, adopting the pen name \"Monsieur Croche\". He expressed trenchant views on composers (\"I hate sentimentality – his name is Camille Saint-Saëns\"), institutions (on the Paris Opéra: \"A stranger would take it for a railway station, and, once inside, would mistake it for a Turkish bath\"), conductors (\"Nikisch is a unique virtuoso, so much so that his virtuosity seems to make him forget the claims of good taste\"), musical politics (\"The English actually think that a musician can manage an opera house successfully!\"), and audiences (\"their almost drugged expression of boredom, indifference and even stupidity\"). He later collected his criticisms with a view to their publication as a book; it was published after his death as Monsieur Croche, Antidilettante.",
"title": "Life and career"
},
{
"paragraph_id": 22,
"text": "In January 1902 rehearsals began at the Opéra-Comique for the opening of Pelléas et Mélisande. For three months, Debussy attended rehearsals practically every day. In February there was conflict between Maeterlinck on the one hand and Debussy, Messager and Carré on the other about the casting of Mélisande. Maeterlinck wanted his mistress, Georgette Leblanc, to sing the role, and was incensed when she was passed over in favour of the Scottish soprano Mary Garden. The opera opened on 30 April 1902, and although the first-night audience was divided between admirers and sceptics, the work quickly became a success. It made Debussy a well-known name in France and abroad; The Times commented that the opera had \"provoked more discussion than any work of modern times, excepting, of course, those of Richard Strauss\". The Apaches, led by Ravel (who attended every one of the 14 performances in the first run), were loud in their support; the conservative faculty of the Conservatoire tried in vain to stop its students from seeing the opera. The vocal score was published in early May, and the full orchestral score in 1904.",
"title": "Life and career"
},
{
"paragraph_id": 23,
"text": "In 1903 there was public recognition of Debussy's stature when he was appointed a Chevalier of the Légion d'honneur, but his social standing suffered a great blow when another turn in his private life caused a scandal the following year. One of his pupils was Raoul Bardac, son of Emma and her husband, Parisian banker Sigismond Bardac. Raoul introduced his teacher to his mother, to whom Debussy quickly became greatly attracted. She was sophisticated, a brilliant conversationalist, an accomplished singer, and relaxed about marital fidelity, having been the mistress and muse of Gabriel Fauré a few years earlier. After despatching Lilly to her parental home at Bichain in Villeneuve-la-Guyard on 15 July 1904, Debussy took Emma away, staying incognito in Jersey and then at Pourville in Normandy. He wrote to his wife on 11 August from Dieppe, telling her that their marriage was over, but still making no mention of Bardac. When he returned to Paris he set up home on his own, taking a flat in a different arrondissement. On 14 October, five days before their fifth wedding anniversary, Lilly Debussy attempted suicide, shooting herself in the chest with a revolver; she survived, although the bullet remained lodged in her vertebrae for the rest of her life. The ensuing scandal caused Bardac's family to disown her, and Debussy lost many good friends including Dukas and Messager. His relations with Ravel, never close, were exacerbated when the latter joined other former friends of Debussy in contributing to a fund to support the deserted Lilly.",
"title": "Life and career"
},
{
"paragraph_id": 24,
"text": "The Bardacs divorced in May 1905. Finding the hostility in Paris intolerable, Debussy and Emma (now pregnant) went to England. They stayed at the Grand Hotel, Eastbourne in July and August, where Debussy corrected the proofs of his symphonic sketches La mer, celebrating his divorce on 2 August. After a brief visit to London, the couple returned to Paris in September, buying a house in a courtyard development off the Avenue du Bois de Boulogne (now Avenue Foch), Debussy's home for the rest of his life.",
"title": "Life and career"
},
{
"paragraph_id": 25,
"text": "In October 1905 La mer, Debussy's most substantial orchestral work, was premiered in Paris by the Orchestre Lamoureux under the direction of Camille Chevillard; the reception was mixed. Some praised the work, but Pierre Lalo, critic of Le Temps, hitherto an admirer of Debussy, wrote, \"I do not hear, I do not see, I do not smell the sea\". In the same month the composer's only child was born at their home. Claude-Emma, affectionately known as \"Chouchou\", was a musical inspiration to the composer (she was the dedicatee of his Children's Corner suite). She outlived her father by scarcely a year, succumbing to the diphtheria epidemic of 1919. Mary Garden said, \"I honestly don't know if Debussy ever loved anybody really. He loved his music – and perhaps himself. I think he was wrapped up in his genius\", but biographers are agreed that whatever his relations with lovers and friends, Debussy was devoted to his daughter.",
"title": "Life and career"
},
{
"paragraph_id": 26,
"text": "Debussy and Emma Bardac eventually married in 1908, their troubled union enduring for the rest of his life. The following year began well, when at Fauré's invitation, Debussy became a member of the governing council of the Conservatoire. His success in London was consolidated in April 1909, when he conducted Prélude à l'après-midi d'un faune and the Nocturnes at the Queen's Hall; in May he was present at the first London production of Pelléas et Mélisande, at Covent Garden. In the same year, Debussy was diagnosed with colorectal cancer, from which he was to die nine years later.",
"title": "Life and career"
},
{
"paragraph_id": 27,
"text": "Debussy's works began to feature increasingly in concert programmes at home and overseas. In 1910 Gustav Mahler conducted the Nocturnes and Prélude à l'après-midi d'un faune in New York in successive months. In the same year, visiting Budapest, Debussy commented that his works were better known there than in Paris. In 1912 Sergei Diaghilev commissioned a new ballet score, Jeux. That, and the three Images, premiered the following year, were the composer's last orchestral works. Jeux was unfortunate in its timing: two weeks after the premiere, in March 1913, Diaghilev presented the first performance of Stravinsky's The Rite of Spring, a sensational event that monopolised discussion in musical circles, and effectively sidelined Jeux along with Fauré's Pénélope, which had opened a week before.",
"title": "Life and career"
},
{
"paragraph_id": 28,
"text": "In 1915 Debussy underwent one of the earliest colostomy operations. It achieved only a temporary respite, and occasioned him considerable frustration (\"There are mornings when the effort of dressing seems like one of the twelve labours of Hercules\"). He also had a fierce enemy at this period in the form of Camille Saint-Saëns, who in a letter to Fauré condemned Debussy's En blanc et noir: \"It's incredible, and the door of the Institut [de France] must at all costs be barred against a man capable of such atrocities\". Saint-Saëns had been a member of the Institut since 1881: Debussy never became one. His health continued to decline; he gave his final concert on 14 September 1917 and became bedridden in early 1918.",
"title": "Life and career"
},
{
"paragraph_id": 29,
"text": "Debussy died on 25 March 1918 at his home. The First World War was still raging and Paris was under German aerial and artillery bombardment. The military situation did not permit the honour of a public funeral with ceremonious graveside orations. The funeral procession made its way through deserted streets to a temporary grave at Père Lachaise Cemetery as the German guns bombarded the city. Debussy's body was reinterred the following year in the small Passy Cemetery sequestered behind the Trocadéro, fulfilling his wish to rest \"among the trees and the birds\"; his wife and daughter are buried with him.",
"title": "Life and career"
},
{
"paragraph_id": 30,
"text": "In a survey of Debussy's oeuvre shortly after the composer's death, the critic Ernest Newman wrote, \"It would be hardly too much to say that Debussy spent a third of his life in the discovery of himself, a third in the free and happy realisation of himself, and the final third in the partial, painful loss of himself\". Later commentators have rated some of the late works more highly than Newman and other contemporaries did, but much of the music for which Debussy is best known is from the middle years of his career.",
"title": "Works"
},
{
"paragraph_id": 31,
"text": "The analyst David Cox wrote in 1974 that Debussy, admiring Wagner's attempts to combine all the creative arts, \"created a new, instinctive, dreamlike world of music, lyrical and pantheistic, contemplative and objective – a kind of art, in fact, which seemed to reach out into all aspects of experience\". In 1988 the composer and scholar Wilfrid Mellers wrote of Debussy:",
"title": "Works"
},
{
"paragraph_id": 32,
"text": "Because of, rather than in spite of, his preoccupation with chords in themselves, he deprived music of the sense of harmonic progression, broke down three centuries' dominance of harmonic tonality, and showed how the melodic conceptions of tonality typical of primitive folk-music and of medieval music might be relevant to the twentieth century",
"title": "Works"
},
{
"paragraph_id": 33,
"text": "Debussy did not give his works opus numbers, apart from his String Quartet, Op. 10 in G minor (also the only work where the composer's title included a key). His works were catalogued and indexed by the musicologist François Lesure in 1977 (revised in 2003) and their Lesure number (\"L\" followed by a number) is sometimes used as a suffix to their title in concert programmes and recordings.",
"title": "Works"
},
{
"paragraph_id": 34,
"text": "Debussy's musical development was slow, and as a student he was adept enough to produce for his teachers at the Conservatoire works that would conform to their conservative precepts. His friend Georges Jean-Aubry commented that Debussy \"admirably imitated Massenet's melodic turns of phrase\" in the cantata L'enfant prodigue (1884) which won him the Prix de Rome. A more characteristically Debussian work from his early years is La Damoiselle élue, recasting the traditional form for oratorios and cantatas, using a chamber orchestra and a small body of choral tone and using new or long-neglected scales and harmonies. His early mélodies, inspired by Marie Vasnier, are more virtuosic in character than his later works in the genre, with extensive wordless vocalise; from the Ariettes oubliées (1885–1887) onwards he developed a more restrained style. He wrote his own poems for the Proses lyriques (1892–1893) but, in the view of the musical scholar Robert Orledge, \"his literary talents were not on a par with his musical imagination\".",
"title": "Works"
},
{
"paragraph_id": 35,
"text": "The musicologist Jacques-Gabriel Prod'homme wrote that, together with La Demoiselle élue, the Ariettes oubliées and the Cinq poèmes de Charles Baudelaire (1889) show \"the new, strange way which the young musician will hereafter follow\". Newman concurred: \"There is a good deal of Wagner, especially of Tristan, in the idiom. But the work as a whole is distinctive, and the first in which we get a hint of the Debussy we were to know later – the lover of vague outlines, of half-lights, of mysterious consonances and dissonances of colour, the apostle of languor, the exclusivist in thought and in style.\" During the next few years Debussy developed his personal style, without, at this stage, breaking sharply away from French musical traditions. Much of his music from this period is on a small scale, such as the Two Arabesques, Valse romantique, Suite bergamasque, and the first set of Fêtes galantes. Newman remarked that, like Chopin, the Debussy of this period appears as a liberator from Germanic styles of composition – offering instead \"an exquisite, pellucid style\" capable of conveying \"not only gaiety and whimsicality but emotion of a deeper sort\". In a 2004 study, Mark DeVoto comments that Debussy's early works are harmonically no more adventurous than existing music by Fauré; in a 2007 book about the piano works, Margery Halford observes that Two Arabesques (1888–1891) and \"Rêverie\" (1890) have \"the fluidity and warmth of Debussy's later style\" but are not harmonically innovative. Halford cites the popular \"Clair de Lune\" (1890), the third of the four movements of Suite Bergamasque, as a transitional work pointing towards the composer's mature style.",
"title": "Works"
},
{
"paragraph_id": 36,
"text": "Musicians from Debussy's time onwards have regarded Prélude à l'après-midi d'un faune (1894) as his first orchestral masterpiece. Newman considered it \"completely original in idea, absolutely personal in style, and logical and coherent from first to last, without a superfluous bar or even a superfluous note\"; Pierre Boulez observed, \"Modern music was awakened by Prélude à l'après-midi d'un faune\". Most of the major works for which Debussy is best known were written between the mid-1890s and the mid-1900s. They include the String Quartet (1893), Pelléas et Mélisande (1893–1902), the Nocturnes for Orchestra (1899) and La mer (1903–1905). The suite Pour le piano (1894–1901) is, in Halford's view, one of the first examples of the mature Debussy as a composer for the piano: \"a major landmark ... and an enlargement of the use of piano sonorities\".",
"title": "Works"
},
{
"paragraph_id": 37,
"text": "In the String Quartet (1893), the gamelan sonorities Debussy had heard four years earlier are recalled in the pizzicatos and cross-rhythms of the scherzo. Debussy's biographer Edward Lockspeiser comments that this movement shows the composer's rejection of \"the traditional dictum that string instruments should be predominantly lyrical\". The work influenced Ravel, whose own String Quartet, written ten years later, has noticeably Debussian features. The academic and journalist Stephen Walsh calls Pelléas et Mélisande (begun 1893, staged 1902) \"a key work for the 20th century\". The composer Olivier Messiaen was fascinated by its \"extraordinary harmonic qualities and ... transparent instrumental texture\". The opera is composed in what Alan Blyth describes as a sustained and heightened recitative style, with \"sensuous, intimate\" vocal lines. It influenced composers as different as Stravinsky and Puccini.",
"title": "Works"
},
{
"paragraph_id": 38,
"text": "Orledge describes the Nocturnes as exceptionally varied in texture, \"ranging from the Musorgskian start of 'Nuages', through the approaching brass band procession in 'Fêtes', to the wordless female chorus in 'Sirènes'\". Orledge considers the last a pre-echo of the marine textures of La mer. Estampes for piano (1903) gives impressions of exotic locations, with further echoes of the gamelan in its pentatonic structures. Debussy believed that since Beethoven, the traditional symphonic form had become formulaic, repetitive and obsolete. The three-part, cyclic symphony by César Franck (1888) was more to his liking, and its influence can be found in La mer (1905); this uses a quasi-symphonic form, its three sections making up a giant sonata-form movement with, as Orledge observes, a cyclic theme, in the manner of Franck. The central \"Jeux de vagues\" section has the function of a symphonic development section leading into the final \"Dialogue du vent et de la mer\", \"a powerful essay in orchestral colour and sonority\" (Orledge) which reworks themes from the first movement. The reviews were sharply divided. Some critics thought the treatment less subtle and less mysterious than his previous works, and even a step backward; others praised its \"power and charm\", its \"extraordinary verve and brilliant fantasy\", and its strong colours and definite lines.",
"title": "Works"
},
{
"paragraph_id": 39,
"text": "Of the later orchestral works, Images (1905–1912) is better known than Jeux (1913). The former follows the tripartite form established in the Nocturnes and La mer, but differs in employing traditional British and French folk tunes, and in making the central movement, \"Ibéria\", far longer than the outer ones, and subdividing it into three parts, all inspired by scenes from Spanish life. Although considering Images \"the pinnacle of Debussy's achievement as a composer for orchestra\", Trezise notes a contrary view that the accolade belongs to the ballet score Jeux. The latter failed as a ballet because of what Jann Pasler describes as a banal scenario, and the score was neglected for some years. Recent analysts have found it a link between traditional continuity and thematic growth within a score and the desire to create discontinuity in a way mirrored in later 20th century music. In this piece, Debussy abandoned the whole-tone scale he had often favoured previously in favour of the octatonic scale with what the Debussy scholar François Lesure describes as its tonal ambiguities.",
"title": "Works"
},
{
"paragraph_id": 40,
"text": "Among the late piano works are two books of Préludes (1909–10, 1911–13), short pieces that depict a wide range of subjects. Lesure comments that they range from the frolics of minstrels at Eastbourne in 1905 and the American acrobat \"General Lavine\" \"to dead leaves and the sounds and scents of the evening air\". En blanc et noir (In white and black, 1915), a three-movement work for two pianos, is a predominantly sombre piece, reflecting the war and national danger. The Études (1915) for piano have divided opinion. Writing soon after Debussy's death, Newman found them laboured – \"a strange last chapter in a great artist's life\"; Lesure, writing eighty years later, rates them among Debussy's greatest late works: \"Behind a pedagogic exterior, these 12 pieces explore abstract intervals, or – in the last five – the sonorities and timbres peculiar to the piano.\" In 1914 Debussy started work on a planned set of six sonatas for various instruments. His fatal illness prevented him from completing the set, but those for cello and piano (1915), flute, viola and harp (1915), and violin and piano (1917 – his last completed work) are all concise, three-movement pieces, more diatonic in nature than some of his other late works.",
"title": "Works"
},
{
"paragraph_id": 41,
"text": "Le Martyre de saint Sébastien (1911), originally a five-act musical play to a text by Gabriele D'Annunzio that took nearly five hours in performance, was not a success, and the music is now more often heard in a concert (or studio) adaptation with narrator, or as an orchestral suite of \"Fragments symphoniques\". Debussy enlisted the help of André Caplet in orchestrating and arranging the score. Two late stage works, the ballets Khamma (1912) and La boîte à joujoux (1913), were left with the orchestration incomplete, and were completed by Charles Koechlin and Caplet, respectively.",
"title": "Works"
},
{
"paragraph_id": 42,
"text": "The application of the term \"Impressionist\" to Debussy and the music he influenced has been much debated, both during his lifetime and since. The analyst Richard Langham Smith writes that Impressionism was originally a term coined to describe a style of late 19th-century French painting, typically scenes suffused with reflected light in which the emphasis is on the overall impression rather than outline or clarity of detail, as in works by Monet, Pissarro, Renoir and others. Langham Smith writes that the term became transferred to the compositions of Debussy and others which were \"concerned with the representation of landscape or natural phenomena, particularly the water and light imagery dear to Impressionists, through subtle textures suffused with instrumental colour\".",
"title": "Style"
},
{
"paragraph_id": 43,
"text": "Among painters, Debussy particularly admired Turner, but also drew inspiration from Whistler. With the latter in mind the composer wrote to the violinist Eugène Ysaÿe in 1894 describing the orchestral Nocturnes as \"an experiment in the different combinations that can be obtained from one colour – what a study in grey would be in painting.\"",
"title": "Style"
},
{
"paragraph_id": 44,
"text": "Debussy strongly objected to the use of the word \"Impressionism\" for his (or anybody else's) music, but it has continually been attached to him since the assessors at the Conservatoire first applied it, opprobriously, to his early work Printemps. Langham Smith comments that Debussy wrote many piano pieces with titles evocative of nature – \"Reflets dans l'eau\" (1905), \"Les Sons et les parfums tournent dans l'air du soir\" (1910) and \"Brouillards\" (1913) – and suggests that the Impressionist painters' use of brush-strokes and dots is paralleled in the music of Debussy. Although Debussy said that anyone using the term (whether about painting or music) was an imbecile, some Debussy scholars have taken a less absolutist line. Lockspeiser calls La mer \"the greatest example of an orchestral Impressionist work\", and more recently in The Cambridge Companion to Debussy Nigel Simeone comments, \"It does not seem unduly far-fetched to see a parallel in Monet's seascapes\".",
"title": "Style"
},
{
"paragraph_id": 45,
"text": "In this context may be placed Debussy's pantheistic eulogy to Nature, in a 1911 interview with Henry Malherbe:",
"title": "Style"
},
{
"paragraph_id": 46,
"text": "I have made mysterious Nature my religion ... When I gaze at a sunset sky and spend hours contemplating its marvellous ever-changing beauty, an extraordinary emotion overwhelms me. Nature in all its vastness is truthfully reflected in my sincere though feeble soul. Around me are the trees stretching up their branches to the skies, the perfumed flowers gladdening the meadow, the gentle grass-carpeted earth, ... and my hands unconsciously assume an attitude of adoration.",
"title": "Style"
},
{
"paragraph_id": 47,
"text": "In contrast to the \"impressionistic\" characterisation of Debussy's music, several writers have suggested that he structured at least some of his music on rigorous mathematical lines. In 1983 the pianist and scholar Roy Howat published a book contending that certain of Debussy's works are proportioned using mathematical models, even while using an apparent classical structure such as sonata form. Howat suggests that some of Debussy's pieces can be divided into sections that reflect the golden ratio, which is approximated by ratios of consecutive numbers in the Fibonacci sequence. Simon Trezise, in his 1994 book Debussy: La Mer, finds the intrinsic evidence \"remarkable\", with the caveat that no written or reported evidence suggests that Debussy deliberately sought such proportions. Lesure takes a similar view, endorsing Howat's conclusions while not taking a view on Debussy's conscious intentions.",
"title": "Style"
},
{
"paragraph_id": 48,
"text": "Debussy wrote \"We must agree that the beauty of a work of art will always remain a mystery [...] we can never be absolutely sure 'how it's made.' We must at all costs preserve this magic which is peculiar to music and to which music, by its nature, is of all the arts the most receptive.\"",
"title": "Style"
},
{
"paragraph_id": 49,
"text": "Nevertheless, there are many indicators of the sources and elements of Debussy's idiom. Writing in 1958, the critic Rudolph Reti summarised six features of Debussy's music, which he asserted \"established a new concept of tonality in European music\": the frequent use of lengthy pedal points – \"not merely bass pedals in the actual sense of the term, but sustained 'pedals' in any voice\"; glittering passages and webs of figurations which distract from occasional absence of tonality; frequent use of parallel chords which are \"in essence not harmonies at all, but rather 'chordal melodies', enriched unisons\", described by some writers as non-functional harmonies; bitonality, or at least bitonal chords; use of the whole-tone and pentatonic scales; and unprepared modulations, \"without any harmonic bridge\". Reti concludes that Debussy's achievement was the synthesis of monophonic based \"melodic tonality\" with harmonies, albeit different from those of \"harmonic tonality\".",
"title": "Style"
},
{
"paragraph_id": 50,
"text": "In 1889, Debussy held conversations with his former teacher Guiraud, which included exploration of harmonic possibilities at the piano. The discussion, and Debussy's chordal keyboard improvisations, were noted by a younger pupil of Guiraud, Maurice Emmanuel. The chord sequences played by Debussy include some of the elements identified by Reti. They may also indicate the influence on Debussy of Satie's 1887 Trois Sarabandes. A further improvisation by Debussy during this conversation included a sequence of whole tone harmonies which may have been inspired by the music of Glinka or Rimsky-Korsakov which was becoming known in Paris at this time. During the conversation, Debussy told Guiraud, \"There is no theory. You have only to listen. Pleasure is the law!\" – although he also conceded, \"I feel free because I have been through the mill, and I don't write in the fugal style because I know it.\"",
"title": "Style"
},
{
"paragraph_id": 51,
"text": "\"Chabrier, Moussorgsky, Palestrina, voilà ce que j'aime\" – they are what I love.",
"title": "Influences"
},
{
"paragraph_id": 52,
"text": "Debussy in 1893",
"title": "Influences"
},
{
"paragraph_id": 53,
"text": "Among French predecessors, Chabrier was an important influence on Debussy (as he was on Ravel and Poulenc); Howat has written that Chabrier's piano music such as \"Sous-bois\" and \"Mauresque\" in the Pièces pittoresques explored new sound-worlds of which Debussy made effective use 30 years later. Lesure finds traces of Gounod and Massenet in some of Debussy's early songs, and remarks that it may have been from the Russians – Tchaikovsky, Balakirev, Rimsky-Korsakov, Borodin and Mussorgsky – that Debussy acquired his taste for \"ancient and oriental modes and for vivid colorations, and a certain disdain for academic rules\". Lesure also considers that Mussorgsky's opera Boris Godunov directly influenced Debussy's Pelléas et Mélisande. In the music of Palestrina, Debussy found what he called \"a perfect whiteness\", and he felt that although Palestrina's musical forms had a \"strict manner\", they were more to his taste than the rigid rules prevailing among 19th-century French composers and teachers. He drew inspiration from what he called Palestrina's \"harmony created by melody\", finding an arabesque-like quality in the melodic lines.",
"title": "Influences"
},
{
"paragraph_id": 54,
"text": "Debussy opined that Chopin was \"the greatest of them all, for through the piano he discovered everything\"; he professed his \"respectful gratitude\" for Chopin's piano music. He was torn between dedicating his own Études to Chopin or to François Couperin, whom he also admired as a model of form, seeing himself as heir to their mastery of the genre. Howat cautions against the assumption that Debussy's Ballade (1891) and Nocturne (1892) are influenced by Chopin – in Howat's view they owe more to Debussy's early Russian models – but Chopin's influence is found in other early works such as the Two arabesques (1889–1891). In 1914 the publisher A. Durand & fils began publishing scholarly new editions of the works of major composers, and Debussy undertook the supervision of the editing of Chopin's music.",
"title": "Influences"
},
{
"paragraph_id": 55,
"text": "Although Debussy was in no doubt of Wagner's stature, he was only briefly influenced by him in his compositions, after La damoiselle élue and the Cinq poèmes de Baudelaire (both begun in 1887). According to Pierre Louÿs, Debussy \"did not see 'what anyone can do beyond Tristan',\" although he admitted that it was sometimes difficult to avoid \"the ghost of old Klingsor, alias Richard Wagner, appearing at the turning of a bar\". After Debussy's short Wagnerian phase, he started to become interested in non-Western music and its unfamiliar approaches to composition. The piano piece Golliwogg's Cakewalk, from the 1908 suite Children's Corner, contains a parody of music from the introduction to Tristan, in which, in the opinion of the musicologist Lawrence Kramer, Debussy escapes the shadow of the older composer and \"smilingly relativizes Wagner into insignificance\".",
"title": "Influences"
},
{
"paragraph_id": 56,
"text": "A contemporary influence was Erik Satie, according to Nichols Debussy's \"most faithful friend\" amongst French musicians. Debussy's orchestration in 1896 of Satie's Gymnopédies (which had been written in 1887) \"put their composer on the map\" according to the musicologist Richard Taruskin, and the Sarabande from Debussy's Pour le piano (1901) \"shows that [Debussy] knew Satie's Trois Sarabandes at a time when only a personal friend of the composer could have known them.\" (They were not published until 1911). Debussy's interest in the popular music of his time is evidenced not only by the Golliwogg's Cakewalk and other piano pieces featuring rag-time, such as The Little Nigar (Debussy's spelling) (1909), but by the slow waltz La plus que lente (The more than slow), based on the style of the gipsy violinist at a Paris hotel (to whom he gave the manuscript of the piece).",
"title": "Influences"
},
{
"paragraph_id": 57,
"text": "In addition to the composers who influenced his own compositions, Debussy held strong views about several others. He was for the most part enthusiastic about Richard Strauss and Stravinsky, respectful of Mozart and was in awe of Bach, whom he called the \"good God of music\" (le Bon Dieu de la musique). His relationship to Beethoven was complex; he was said to refer to him as le vieux sourd ('the old deaf one') and asked one young pupil not to play Beethoven's music for \"it is like somebody dancing on my grave;\" but he believed that Beethoven had profound things to say, yet did not know how to say them, \"because he was imprisoned in a web of incessant restatement and of German aggressiveness.\" He was not in sympathy with Schubert, Schumann, Brahms and Mendelssohn, the latter being described as a \"facile and elegant notary\".",
"title": "Influences"
},
{
"paragraph_id": 58,
"text": "With the advent of the First World War, Debussy became ardently patriotic in his musical opinions. Writing to Stravinsky, he asked \"How could we not have foreseen that these men were plotting the destruction of our art, just as they had planned the destruction of our country?\" In 1915 he complained that \"since Rameau we have had no purely French tradition [...] We tolerated overblown orchestras, tortuous forms [...] we were about to give the seal of approval to even more suspect naturalizations when the sound of gunfire put a sudden stop to it all.\" Taruskin writes that some have seen this as a reference to the composers Gustav Mahler and Arnold Schoenberg, both born Jewish. In 1912 Debussy had remarked to his publisher of the opera Ariane et Barbe-bleue by the (also Jewish) composer Paul Dukas, \"You're right, [it] is a masterpiece – but it's not a masterpiece of French music.\"",
"title": "Influences"
},
{
"paragraph_id": 59,
"text": "Despite his lack of formal schooling, Debussy read widely and found inspiration in literature. Lesure writes, \"The development of free verse in poetry and the disappearance of the subject or model in painting influenced him to think about issues of musical form.\" Debussy was influenced by the Symbolist poets. These writers, who included Verlaine, Mallarmé, Maeterlinck and Rimbaud, reacted against the realism, naturalism, objectivity and formal conservatism that prevailed in the 1870s. They favoured poetry using suggestion rather than direct statement; the literary scholar Chris Baldrick writes that they evoked \"subjective moods through the use of private symbols, while avoiding the description of external reality or the expression of opinion\". Debussy was much in sympathy with the Symbolists' desire to bring poetry closer to music, became friendly with several leading exponents, and set many Symbolist works throughout his career.",
"title": "Influences"
},
{
"paragraph_id": 60,
"text": "Debussy's literary inspirations were mostly French, but he did not overlook foreign writers. As well as Maeterlinck for Pelléas et Mélisande, he drew on Shakespeare and Dickens for two of his Préludes for piano – La Danse de Puck (Book 1, 1910) and Hommage à S. Pickwick Esq. P.P.M.P.C. (Book 2, 1913). He set Dante Gabriel Rossetti's The Blessed Damozel in his early cantata, La Damoiselle élue (1888). He wrote incidental music for King Lear and planned an opera based on As You Like It, but abandoned that once he turned his attention to setting Maeterlinck's play. In 1890 he began work on an orchestral piece inspired by Edgar Allan Poe's The Fall of the House of Usher and later sketched the libretto for an opera, La chute de la maison Usher. Another project inspired by Poe – an operatic version of The Devil in the Belfry did not progress beyond sketches. French writers whose words he set include Paul Bourget, Alfred de Musset, Théodore de Banville, Leconte de Lisle, Théophile Gautier, Paul Verlaine, François Villon, and Mallarmé – the last of whom also provided Debussy with the inspiration for one of his most popular orchestral pieces, Prélude à l'après-midi d'un faune.",
"title": "Influences"
},
{
"paragraph_id": 61,
"text": "Debussy is widely regarded as one of the most influential composers of the 20th century. Roger Nichols writes that \"if one omits Schoenberg [...] a list of 20th-century composers influenced by Debussy is practically a list of 20th-century composers tout court.\"",
"title": "Influence on later composers"
},
{
"paragraph_id": 62,
"text": "Bartók first encountered Debussy's music in 1907 and later said that \"Debussy's great service to music was to reawaken among all musicians an awareness of harmony and its possibilities\". Not only Debussy's use of whole-tone scales, but also his style of word-setting in Pelléas et Mélisande, were the subject of study by Leoš Janáček while he was writing his 1921 opera Káťa Kabanová. Stravinsky was more ambivalent about Debussy's music (he thought Pelléas \"a terrible bore ... in spite of many wonderful pages\") but the two composers knew each other and Stravinsky's Symphonies of Wind Instruments (1920) was written as a memorial for Debussy.",
"title": "Influence on later composers"
},
{
"paragraph_id": 63,
"text": "In the aftermath of the First World War, the young French composers of Les Six reacted against what they saw as the poetic, mystical quality of Debussy's music in favour of something more hard-edged. Their sympathiser and self-appointed spokesman Jean Cocteau wrote in 1918: \"Enough of nuages, waves, aquariums, ondines and nocturnal perfumes,\" pointedly alluding to the titles of pieces by Debussy. Later generations of French composers had a much more positive relationship with his music. Messiaen was given a score of Pelléas et Mélisande as a boy and said that it was \"a revelation, love at first sight\" and \"probably the most decisive influence I have been subject to\". Boulez also discovered Debussy's music at a young age and said that it gave him his first sense of what modernity in music could mean.",
"title": "Influence on later composers"
},
{
"paragraph_id": 64,
"text": "Among contemporary composers George Benjamin has described Prélude à l'après-midi d'un faune as \"the definition of perfection\"; he has conducted Pelléas et Mélisande and the critic Rupert Christiansen detects the influence of the work in Benjamin's opera Written on Skin (2012). Others have made orchestrations of some of the piano and vocal works, including John Adams's version of four of the Baudelaire songs (Le Livre de Baudelaire, 1994), Robin Holloway's of En blanc et noir (2002), and Colin Matthews's of both books of Préludes (2001–2006).",
"title": "Influence on later composers"
},
{
"paragraph_id": 65,
"text": "The pianist Stephen Hough believes that Debussy's influence also extends to jazz and suggests that Reflets dans l'eau can be heard in the harmonies of Bill Evans.",
"title": "Influence on later composers"
},
{
"paragraph_id": 66,
"text": "In 1904, Debussy played the piano accompaniment for Mary Garden in recordings for the Compagnie française du Gramophone of four of his songs: three mélodies from the Verlaine cycle Ariettes oubliées – \"Il pleure dans mon coeur\", \"L'ombre des arbres\" and \"Green\" – and \"Mes longs cheveux\", from Act III of Pelléas et Mélisande. He made a set of piano rolls for the Welte-Mignon company in 1913. They contain fourteen of his pieces: \"D'un cahier d'esquisses\", \"La plus que lente\", \"La soirée dans Grenade\", all six movements of Children's Corner, and five of the Preludes: \"Danseuses de Delphes\", \"Le vent dans la plaine\", \"La cathédrale engloutie\", \"La danse de Puck\" and \"Minstrels\". The 1904 and 1913 sets have been transferred to compact disc.",
"title": "Recordings"
},
{
"paragraph_id": 67,
"text": "Contemporaries of Debussy who made recordings of his music included the pianists Ricardo Viñes (in \"Poissons d'or\" from Images and \"La soirée dans Grenade\" from Estampes); Alfred Cortot (numerous solo pieces as well as the Violin Sonata with Jacques Thibaud and the Chansons de Bilitis with Maggie Teyte); and Marguerite Long (\"Jardins sous la pluie\" and \"Arabesques\"). Singers in Debussy's mélodies or excerpts from Pelléas et Mélisande included Jane Bathori, Claire Croiza, Charles Panzéra and Ninon Vallin; and among the conductors in the major orchestral works were Ernest Ansermet, Désiré-Émile Inghelbrecht, Pierre Monteux and Arturo Toscanini, and in the Petite Suite, Henri Büsser, who had prepared the orchestration for Debussy. Many of these early recordings have been reissued on CD.",
"title": "Recordings"
},
{
"paragraph_id": 68,
"text": "In more recent times Debussy's output has been extensively recorded. In 2018, to mark the centenary of the composer's death, Warner Classics, with contributions from other companies, issued a 33-CD set that is claimed to include all the music Debussy wrote.",
"title": "Recordings"
}
] | (Achille) Claude Debussy was a French composer. He is sometimes seen as the first Impressionist composer, although he vigorously rejected the term. He was among the most influential composers of the late 19th and early 20th centuries. Born to a family of modest means and little cultural involvement, Debussy showed enough musical talent to be admitted at the age of ten to France's leading music college, the Conservatoire de Paris. He originally studied the piano, but found his vocation in innovative composition, despite the disapproval of the Conservatoire's conservative professors. He took many years to develop his mature style, and was nearly 40 when he achieved international fame in 1902 with the only opera he completed, Pelléas et Mélisande. Debussy's orchestral works include Prélude à l'après-midi d'un faune (1894), Nocturnes (1897–1899) and Images (1905–1912). His music was to a considerable extent a reaction against Wagner and the German musical tradition. He regarded the classical symphony as obsolete and sought an alternative in his "symphonic sketches", La mer (1903–1905). His piano works include sets of 24 Préludes and 12 Études. Throughout his career he wrote mélodies based on a wide variety of poetry, including his own. He was greatly influenced by the Symbolist poetic movement of the later 19th century. A small number of works, including the early La Damoiselle élue and the late Le Martyre de saint Sébastien have important parts for chorus. In his final years, he focused on chamber music, completing three of six planned sonatas for different combinations of instruments. With early influences including Russian and Far Eastern music and works by Chopin, Debussy developed his own style of harmony and orchestral colouring, derided – and unsuccessfully resisted – by much of the musical establishment of the day. His works have strongly influenced a wide range of composers including Béla Bartók, Olivier Messiaen, George Benjamin, and the jazz pianist and composer Bill Evans. Debussy died from cancer at his home in Paris at the age of 55 after a composing career of a little more than 30 years. | 2001-09-04T21:03:31Z | 2023-12-23T09:47:14Z | [
"Template:Short description",
"Template:Lang",
"Template:ChoralWiki",
"Template:'\"",
"Template:Subscription",
"Template:Cite Grove",
"Template:Subject bar",
"Template:Redirect",
"Template:Center",
"Template:Blockquote",
"Template:Reflist",
"Template:Webarchive",
"Template:Featured article",
"Template:Bots",
"Template:Use British English",
"Template:IPA-fr",
"Template:Refbegin",
"Template:Refn",
"Template:Listen",
"Template:Refend",
"Template:Authority control",
"Template:Use dmy dates",
"Template:See also",
"Template:Cite web",
"Template:Cite book",
"Template:BBC composer page",
"Template:Quote box",
"Template:Claude Debussy",
"Template:Impressionist music",
"Template:Modernism",
"Template:C.",
"Template:IMSLP"
] | https://en.wikipedia.org/wiki/Claude_Debussy |
6,261 | Charles Baxter (author) | Charles Morley Baxter (born May 13, 1947) is an American novelist, essayist, and poet.
Baxter was born in Minneapolis, Minnesota, to John and Mary Barber (Eaton) Baxter. He graduated from Macalester College in Saint Paul in 1969. In 1974 he received his PhD in English from the University at Buffalo with a thesis on Djuna Barnes, Malcolm Lowry, and Nathanael West.
Baxter taught high school in Pinconning, Michigan for a year before beginning his university teaching career at Wayne State University in Detroit, Michigan. He then moved to the University of Michigan, where for many years he directed the Creative Writing MFA program. He was a visiting professor of creative writing at the University of Iowa and at Stanford. He taught at the University of Minnesota and in the Warren Wilson College MFA Program for Writers. He retired in 2020.
He was awarded a Guggenheim Fellowship in 1985. He received the PEN/Malamud Award in 2021 for Excellence in the Short Story.
He married teacher Martha Ann Hauser in 1976, and has a son, Daniel. Baxter and Hauser eventually separated. | [
{
"paragraph_id": 0,
"text": "Charles Morley Baxter (born May 13, 1947) is an American novelist, essayist, and poet.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Baxter was born in Minneapolis, Minnesota, to John and Mary Barber (Eaton) Baxter. He graduated from Macalester College in Saint Paul in 1969. In 1974 he received his PhD in English from the University at Buffalo with a thesis on Djuna Barnes, Malcolm Lowry, and Nathanael West.",
"title": "Biography"
},
{
"paragraph_id": 2,
"text": "Baxter taught high school in Pinconning, Michigan for a year before beginning his university teaching career at Wayne State University in Detroit, Michigan. He then moved to the University of Michigan, where for many years he directed the Creative Writing MFA program. He was a visiting professor of creative writing at the University of Iowa and at Stanford. He taught at the University of Minnesota and in the Warren Wilson College MFA Program for Writers. He retired in 2020.",
"title": "Biography"
},
{
"paragraph_id": 3,
"text": "He was awarded a Guggenheim Fellowship in 1985. He received the PEN/Malamud Award in 2021 for Excellence in the Short Story.",
"title": "Biography"
},
{
"paragraph_id": 4,
"text": "He married teacher Martha Ann Hauser in 1976, and has a son, Daniel. Baxter and Hauser eventually separated.",
"title": "Biography"
}
] | Charles Morley Baxter is an American novelist, essayist, and poet. | 2023-05-01T19:43:33Z | [
"Template:Infobox writer",
"Template:Reflist",
"Template:Cite web",
"Template:Cite book",
"Template:ISBN",
"Template:Authority control",
"Template:Short description",
"Template:Use mdy dates"
] | https://en.wikipedia.org/wiki/Charles_Baxter_(author) |
|
6,262 | Ceres | Ceres most commonly refers to:
Ceres may also refer to: | [
{
"paragraph_id": 0,
"text": "Ceres most commonly refers to:",
"title": ""
},
{
"paragraph_id": 1,
"text": "Ceres may also refer to:",
"title": ""
}
] | Ceres most commonly refers to: Ceres, the largest asteroid and first to be discovered
Ceres (mythology), the Roman goddess of agriculture Ceres may also refer to: | 2001-10-14T23:19:02Z | 2023-12-16T03:19:31Z | [
"Template:Wiktionary",
"Template:TOC right",
"Template:Lang",
"Template:Ship",
"Template:Disambiguation"
] | https://en.wikipedia.org/wiki/Ceres |
6,267 | Cultural imperialism | Cultural imperialism (also cultural colonialism) comprises the cultural dimensions of imperialism. The word "imperialism" describes practices in which a country engages culture (language, tradition, and ritual, politics, economics) to create and maintain unequal social and economic relationships among social groups. Cultural imperialism often uses wealth, media power and violence to implement the system of cultural hegemony that legitimizes imperialism.
Cultural imperialism may take various forms, such as an attitude, a formal policy, or military action—insofar as each of these reinforces the empire's cultural hegemony. Research on the topic occurs in scholarly disciplines, and is especially prevalent in communication and media studies, education, foreign policy, history, international relations, linguistics, literature, post-colonialism, science, sociology, social theory, environmentalism, and sports.
Cultural imperialism may be distinguished from the natural process of cultural diffusion. The spread of culture around the world is referred to as cultural globalization.
Although the Oxford English Dictionary has a 1921 reference to the "cultural imperialism of the Russians", John Tomlinson, in his book on the subject, writes that the term emerged in the 1960s and has been a focus of research since at least the 1970s. Terms such as "media imperialism", "structural imperialism", "cultural dependency and domination", "cultural synchronization", "electronic colonialism", "ideological imperialism", and "economic imperialism" have all been used to describe the same basic notion of cultural imperialism.
The term refers largely to the exercise of power in a cultural relationship in which the principles, ideas, practices, and values of a powerful, invading society are imposed upon indigenous cultures in the occupied areas. The process is often used to describe examples of when the compulsory practices of the cultural traditions of the imperial social group are implemented upon a conquered social group. The process is also present when powerful nations are able to flood the information and media space with their ideas, limiting countries and communities ability to compete and expose people to locally created content.
Cultural imperialism has been called a process that intends to transition the "cultural symbols of the invading communities from 'foreign' to 'natural,''domestic,'" comments Jeffrey Herlihy-Mera. He described the process as being carried out in three phases by merchants, then the military, then politicians. While the third phase continues "in perpetuity", cultural imperialism tends to be "gradual, contested (and continues to be contested), and is by nature incomplete. The partial and imperfect configuration of this ontology takes an implicit conceptualization of reality and attempts—and often fails—to elide other forms of collective existence." In order to achieve that end, cultural engineering projects strive to "isolate residents within constructed spheres of symbols" such that they (eventually, in some cases after several generations) abandon other cultures and identify with the new symbols. "The broader intended outcome of these interventions might be described as a common recognition of possession of the land itself (on behalf of the organizations publishing and financing the images)."
For Herbert Schiller, cultural imperialism refers to the American Empire's "coercive and persuasive agencies, and their capacity to promote and universalize an American 'way of life' in other countries without any reciprocation of influence." According to Schiller, cultural imperialism "pressured, forced and bribed" societies to integrate with the U.S.'s expansive capitalist model but also incorporated them with attraction and persuasion by winning "the mutual consent, even solicitation of the indigenous rulers." He continues remarks that it is:
the sum processes by which a society is brought into the modern [U.S.-centered] world system and how its dominating stratum is attracted, pressured, forced, and sometimes bribed into shaping social institutions to correspond to, or even promote, the values and structures of the dominating centres of the system. The public media are the foremost example of operating enterprises that are used in the penetrative process. For penetration on a significant scale the media themselves must be captured by the dominating/penetrating power. This occurs largely through the commercialization of broadcasting.
The historical contexts, iterations, complexities, and politics of Schiller's foundational and substantive theorization of cultural imperialism in international communication and media studies are discussed in detail by political economy of communication researchers Richard Maxwell, Vincent Mosco, Graham Murdock, and Tanner Mirrlees.
Downing and Sreberny-Mohammadi state: "Cultural imperialism signifies the dimensions of the process that go beyond economic exploitation or military force. In the history of colonialism, (i.e., the form of imperialism in which the government of the colony is run directly by foreigners), the educational and media systems of many Third World countries have been set up as replicas of those in Britain, France, or the United States and carry their values. Western advertising has made further inroads, as have architectural and fashion styles. Subtly but powerfully, the message has often been insinuated that Western cultures are superior to the cultures of the Third World."
In poststructuralist and postcolonial theory, cultural imperialism is often understood as the cultural legacy of Western colonialism, or forms of social action contributing to the continuation of Western hegemony. To some outside of the realm of this discourse, the term is critiqued as being unclear, unfocused, and/or contradictory in nature.
The work of French philosopher and social theorist Michel Foucault has heavily influenced use of the term cultural imperialism, particularly his philosophical interpretation of power and his concept of governmentality. Following an interpretation of power similar to that of Machiavelli, Foucault defines power as immaterial, as a "certain type of relation between individuals" that has to do with complex strategic social positions that relate to the subject's ability to control its environment and influence those around itself. According to Foucault, power is intimately tied with his conception of truth. "Truth", as he defines it, is a "system of ordered procedures for the production, regulation, distribution, circulation, and operation of statements" which has a "circular relation" with systems of power. Therefore, inherent in systems of power, is always "truth", which is culturally specific, inseparable from ideology which often coincides with various forms of hegemony. Cultural imperialism may be an example of this.
Foucault's interpretation of governance is also very important in constructing theories of transnational power structure. In his lectures at the Collège de France, Foucault often defines governmentality as the broad art of "governing", which goes beyond the traditional conception of governance in terms of state mandates, and into other realms such as governing "a household, souls, children, a province, a convent, a religious order, a family". This relates directly back to Machiavelli's treatise on how to retain political power at any cost, The Prince, and Foucault's aforementioned conceptions of truth and power. (i.e. various subjectivities are created through power relations that are culturally specific, which lead to various forms of culturally specific governmentality such as neoliberal governmentality.)
Edward Saïd is a founding figure of postcolonialism, established with the book Orientalism (1978), a humanist critique of The Enlightenment, which criticises Western knowledge of "The East"—specifically the English and the French constructions of what is and what is not "Oriental". Whereby said "knowledge" then led to cultural tendencies towards a binary opposition of the Orient vs. the Occident, wherein one concept is defined in opposition to the other concept, and from which they emerge as of unequal value. In Culture and Imperialism (1993), the sequel to Orientalism, Saïd proposes that, despite the formal end of the "age of empire" after the Second World War (1939–1945), colonial imperialism left a cultural legacy to the (previously) colonised peoples, which remains in their contemporary civilisations; and that said American cultural imperialism is very influential in the international systems of power.
In "Can the Subaltern Speak?" Gayatri Chakravorty Spivak critiques common representations in the West of the Sati, as being controlled by authors other than the participants (specifically English colonizers and Hindu leaders). Because of this, Spivak argues that the subaltern, referring to the communities that participate in the Sati, are not able to represent themselves through their own voice. Spivak says that cultural imperialism has the power to disqualify or erase the knowledge and mode of education of certain populations that are low on the social and economic hierarchy.
In A Critique of Postcolonial Reason, Spivak argues that Western philosophy has a history of not only exclusion of the subaltern from discourse, but also does not allow them to occupy the space of a fully human subject.
Cultural imperialism can refer to either the forced acculturation of a subject population, or to the voluntary embracing of a foreign culture by individuals who do so of their own free will. Since these are two very different referents, the validity of the term has been called into question.
Cultural influence can be seen by the "receiving" culture as either a threat to or an enrichment of its cultural identity. It seems therefore useful to distinguish between cultural imperialism as an (active or passive) attitude of superiority, and the position of a culture or group that seeks to complement its own cultural production, considered partly deficient, with imported products.
The imported products or services can themselves represent, or be associated with, certain values (such as consumerism). According to one argument, the "receiving" culture does not necessarily perceive this link, but instead absorbs the foreign culture passively through the use of the foreign goods and services. Due to its somewhat concealed, but very potent nature, this hypothetical idea is described by some experts as "banal imperialism". For example, it is argued that while "American companies are accused of wanting to control 95 percent of the world's consumers", "cultural imperialism involves much more than simple consumer goods; it involved the dissemination of American principles such as freedom and democracy", a process which "may sound appealing" but which "masks a frightening truth: many cultures around the world are disappearing due to the overwhelming influence of corporate and cultural America".
Some believe that the newly globalised economy of the late 20th and early 21st century has facilitated this process through the use of new information technology. This kind of cultural imperialism is derived from what is called "soft power". The theory of electronic colonialism extends the issue to global cultural issues and the impact of major multi-media conglomerates, ranging from Paramount, WarnerMedia, AT&T, Disney, News Corp, to Google and Microsoft with the focus on the hegemonic power of these mainly United States-based communication giants.
One of the reasons often given for opposing any form of cultural imperialism, voluntary or otherwise, is the preservation of cultural diversity, a goal seen by some as analogous to the preservation of ecological diversity. Proponents of this idea argue either that such diversity is valuable in itself, to preserve human historical heritage and knowledge, or instrumentally valuable because it makes available more ways of solving problems and responding to catastrophes, natural or otherwise.
Of all the areas of the world that scholars have claimed to be adversely affected by imperialism, Africa is probably the most notable. In the expansive "age of imperialism" of the nineteenth century, scholars have argued that European colonisation in Africa has led to the elimination of many various cultures, worldviews, and epistemologies, particularly through neocolonisation of public education. This, arguably has led to uneven development, and further informal forms of social control having to do with culture and imperialism. A variety of factors, scholars argue, lead to the elimination of cultures, worldviews, and epistemologies, such as "de-linguicization" (replacing native African languages with European ones), devaluing ontologies that are not explicitly individualistic, and at times going as far as to not only define Western culture itself as science, but that non-Western approaches to science, the Arts, indigenous culture, etc. are not even knowledge. One scholar, Ali A. Abdi, claims that imperialism inherently "involve[s] extensively interactive regimes and heavy contexts of identity deformation, misrecognition, loss of self-esteem, and individual and social doubt in self-efficacy." Therefore, all imperialism would always, already be cultural.
Neoliberalism is often critiqued by sociologists, anthropologists, and cultural studies scholars as being culturally imperialistic. Critics of neoliberalism, at times, claim that it is the newly predominant form of imperialism. Other scholars, such as Elizabeth Dunn and Julia Elyachar have claimed that neoliberalism requires and creates its own form of governmentality.
In Dunn's work, Privatizing Poland, she argues that the expansion of the multinational corporation, Gerber, into Poland in the 1990s imposed Western, neoliberal governmentality, ideologies, and epistemologies upon the post-soviet persons hired. Cultural conflicts occurred most notably the company's inherent individualistic policies, such as promoting competition among workers rather than cooperation, and in its strong opposition to what the company owners claimed was bribery.
In Elyachar's work, Markets of Dispossession, she focuses on ways in which, in Cairo, NGOs along with INGOs and the state promoted neoliberal governmentality through schemas of economic development that relied upon "youth microentrepreneurs". Youth microentrepreneurs would receive small loans to build their own businesses, similar to the way that microfinance supposedly operates. Elyachar argues though, that these programs not only were a failure, but that they shifted cultural opinions of value (personal and cultural) in a way that favoured Western ways of thinking and being.
Often, methods of promoting development and social justice are critiqued as being imperialistic in a cultural sense. For example, Chandra Mohanty has critiqued Western feminism, claiming that it has created a misrepresentation of the "third world woman" as being completely powerless, unable to resist male dominance. Thus, this leads to the often critiqued narrative of the "white man" saving the "brown woman" from the "brown man". Other, more radical critiques of development studies, have to do with the field of study itself. Some scholars even question the intentions of those developing the field of study, claiming that efforts to "develop" the Global South were never about the South itself. Instead, these efforts, it is argued, were made in order to advance Western development and reinforce Western hegemony.
The core of cultural imperialism thesis is integrated with the political-economy traditional approach in media effects research. Critics of cultural imperialism commonly claim that non-Western cultures, particularly from the Third World, will forsake their traditional values and lose their cultural identities when they are solely exposed to Western media. Nonetheless, Michael B. Salwen, in his book Critical Studies in Mass Communication (1991), claims that cross-consideration and integration of empirical findings on cultural imperialist influences is very critical in terms of understanding mass media in the international sphere. He recognises both of contradictory contexts on cultural imperialist impacts. The first context is where cultural imperialism imposes socio-political disruptions on developing nations. Western media can distort images of foreign cultures and provoke personal and social conflicts to developing nations in some cases. Another context is that peoples in developing nations resist to foreign media and preserve their cultural attitudes. Although he admits that outward manifestations of Western culture may be adopted, but the fundamental values and behaviours remain still. Furthermore, positive effects might occur when male-dominated cultures adopt the "liberation" of women with exposure to Western media and it stimulates ample exchange of cultural exchange.
Critics of scholars who discuss cultural imperialism have a number of critiques. Cultural imperialism is a term that is only used in discussions where cultural relativism and constructivism are generally taken as true. (One cannot critique promoting Western values if one believes that said values are good. Similarly, one cannot argue that Western epistemology is unjustly promoted in non-Western societies if one believes that those epistemologies are good.) Therefore, those who disagree with cultural relativism and/or constructivism may critique the employment of the term, cultural imperialism on those terms.
John Tomlinson provides a critique of cultural imperialism theory and reveals major problems in the way in which the idea of cultural, as opposed to economic or political, imperialism is formulated. In his book Cultural Imperialism: A Critical Introduction, he delves into the much debated "media imperialism" theory. Summarizing research on the Third World's reception of American television shows, he challenges the cultural imperialism argument, conveying his doubts about the degree to which US shows in developing nations actually carry US values and improve the profits of US companies. Tomlinson suggests that cultural imperialism is growing in some respects, but local transformation and interpretations of imported media products propose that cultural diversification is not at an end in global society. He explains that one of the fundamental conceptual mistakes of cultural imperialism is to take for granted that the distribution of cultural goods can be considered as cultural dominance. He thus supports his argument highly criticising the concept that Americanization is occurring through global overflow of American television products. He points to a myriad of examples of television networks who have managed to dominate their domestic markets and that domestic programs generally top the ratings. He also doubts the concept that cultural agents are passive receivers of information. He states that movement between cultural/geographical areas always involves translation, mutation, adaptation, and the creation of hybridity.
Other key critiques are that the term is not defined well, and employs further terms that are not defined well, and therefore lacks explanatory power, that cultural imperialism is hard to measure, and that the theory of a legacy of colonialism is not always true.
David Rothkopf, managing director of Kissinger Associates and an adjunct professor of international affairs at Columbia University (who also served as a senior U.S. Commerce Department official in the Clinton Administration), wrote about cultural imperialism in his provocatively titled In Praise of Cultural Imperialism? in the summer 1997 issue of Foreign Policy magazine. Rothkopf says that the United States should embrace "cultural imperialism" as in its self-interest. But his definition of cultural imperialism stresses spreading the values of tolerance and openness to cultural change in order to avoid war and conflict between cultures as well as expanding accepted technological and legal standards to provide free traders with enough security to do business with more countries. Rothkopf's definition almost exclusively involves allowing individuals in other nations to accept or reject foreign cultural influences. He also mentions, but only in passing, the use of the English language and consumption of news and popular music and film as cultural dominance that he supports. Rothkopf additionally makes the point that globalisation and the Internet are accelerating the process of cultural influence.
Culture is sometimes used by the organisers of society—politicians, theologians, academics, and families—to impose and ensure order, the rudiments of which change over time as need dictates. One need only look at the 20th century's genocides. In each one, leaders used culture as a political front to fuel the passions of their armies and other minions and to justify their actions among their people.
Rothkopf then cites genocide and massacres in Armenia, Russia, the Holocaust, Cambodia, Bosnia and Herzegovina, Rwanda and East Timor as examples of culture (in some cases expressed in the ideology of "political culture" or religion) being misused to justify violence. He also acknowledges that cultural imperialism in the past has been guilty of forcefully eliminating the cultures of natives in the Americas and in Africa, or through use of the Inquisition, "and during the expansion of virtually every empire." The most important way to deal with cultural influence in any nation, according to Rothkopf, is to promote tolerance and allow, or even promote, cultural diversities that are compatible with tolerance and to eliminate those cultural differences that cause violent conflict:
Cultural dominance can also be seen in the 1930s in Australia where the Aboriginal Assimilation Policy acted as an attempt to wipe out the Native Australian people. The British settlers tried to biologically alter the skin colour of the Australian Aboriginal people through mixed breeding with white people. The policy also made attempts to forcefully conform the Aborigines to western ideas of dress and education.
Although the term was popularised in the 1960s, and was used by its original proponents to refer to cultural hegemonies in a post-colonial world, cultural imperialism has also been used to refer to times further in the past.
The Ancient Greeks are known for spreading their culture around the Mediterranean and Near East through trade and conquest. During the Archaic Period, the burgeoning Greek city-states established settlements and colonies across the Mediterranean Sea, especially in Sicily and southern Italy, influencing the Etruscan and Roman peoples of the region. In the late fourth century BC, Alexander the Great conquered Persian and Indian territories all the way to the Indus River Valley and Punjab, spreading Greek pagan religion, art, and science along the way. This resulted in the rise of Hellenistic kingdoms and cities across Egypt, the Near East, Central Asia, and Northwest India where Greek culture fused with the cultures of the indigenous peoples. The Greek influence prevailed even longer in science and literature, where medieval Muslim scholars in the Middle East studied the writings of Aristotle for scientific learning.
The Roman Empire was also an early example of cultural imperialism. Early Rome, in its conquest of Italy, assimilated the people of Etruria by replacing the Etruscan language with Latin, which led to the demise of that language and many aspects of Etruscan civilisation. Cultural Romanization was imposed on many parts of Rome's empire by "many regions receiving Roman culture unwillingly, as a form of cultural imperialism." For example, when Greece was conquered by the Roman armies, Rome set about altering the culture of Greece to conform with Roman ideals. For instance, the Greek habit of stripping naked, in public, for exercise, was looked on askance by Roman writers, who considered the practice to be a cause of the Greeks' effeminacy and enslavement. The Roman example has been linked to modern instances of European imperialism in African countries, bridging the two instances with Slavoj Zizek's discussions of 'empty signifiers'. The Pax Romana was secured in the empire, in part, by the "forced acculturation of the culturally diverse populations that Rome had conquered."
British worldwide expansion in the 18th and 19th centuries was an economic and political phenomenon. However, "there was also a strong social and cultural dimension to it, which Rudyard Kipling termed the 'white man's burden'." One of the ways this was carried out was by religious proselytising, by, amongst others, the London Missionary Society, which was "an agent of British cultural imperialism." Another way, was by the imposition of educational material on the colonies for an "imperial curriculum". Robin A. Butlin writes, "The promotion of empire through books, illustrative materials, and educational syllabuses was widespread, part of an education policy geared to cultural imperialism". This was also true of science and technology in the empire. Douglas M. Peers and Nandini Gooptu note that "Most scholars of colonial science in India now prefer to stress the ways in which science and technology worked in the service of colonialism, as both a 'tool of empire' in the practical sense and as a vehicle for cultural imperialism. In other words, science developed in India in ways that reflected colonial priorities, tending to benefit Europeans at the expense of Indians, while remaining dependent on and subservient to scientific authorities in the colonial metropolis." British sports were spread across the Empire partially as a way of encouraging British values and cultural uniformity, though this was tempered by the fact that colonised peoples gained a sense of nationalistic pride by defeating the British in their own sports.
The analysis of cultural imperialism carried out by Edward Said drew principally from a study of the British Empire. According to Danilo Raponi, the cultural imperialism of the British in the 19th century had a much wider effect than only in the British Empire. He writes, "To paraphrase Said, I see cultural imperialism as a complex cultural hegemony of a country, Great Britain, that in the 19th century had no rivals in terms of its ability to project its power across the world and to influence the cultural, political and commercial affairs of most countries. It is the 'cultural hegemony' of a country whose power to export the most fundamental ideas and concepts at the basis of its understanding of 'civilisation' knew practically no bounds." In this, for example, Raponi includes Italy.
The New Cambridge Modern History writes about the cultural imperialism of Napoleonic France. Napoleon used the Institut de France "as an instrument for transmuting French universalism into cultural imperialism." Members of the Institute (who included Napoleon), descended upon Egypt in 1798. "Upon arrival they organised themselves into an Institute of Cairo. The Rosetta Stone is their most famous find. The science of Egyptology is their legacy."
After the First World War, Germans were worried about the extent of French influence in the annexed Rhineland, with the French occupation of the Ruhr Valley in 1923. An early use of the term appeared in an essay by Paul Ruhlmann (as "Peter Hartmann") at that date, entitled French Cultural Imperialism on the Rhine.
Keeping in line with the trends of international imperialistic endeavours, the expansion of Canadian and American territory in the 19th century saw cultural imperialism employed as a means of control over indigenous populations. This, when used in conjunction of more traditional forms of ethnic cleansing and genocide in the United States, saw devastating, lasting effects on indigenous communities.
In 2017 Canada celebrated its 150-year anniversary of the confederating of three British colonies. As Catherine Murton Stoehr points out in Origins, a publication organised by the history departments of Ohio State University and Miami University, the occasion came with remembrance of Canada's treatment of First Nations people.
A mere 9 years after the 1867 signing of confederation Canada passed "The Indian Act", a separate and not equal form of government especially for First Nations. The Indian Act remains in place today, confining and constraining Indigenous jurisdiction in every area of life, in direct contravention of the nation's founding treaties with indigenous nations.
Numerous policies focused on indigenous persons came into effect shortly thereafter. Most notable is the use of residential schools across Canada as a means to remove indigenous persons from their culture and instill in them the beliefs and values of the majorised colonial hegemony. The policies of these schools, as described by Ward Churchill in his book Kill the Indian, Save the Man, were to forcefully assimilate students who were often removed with force from their families. These schools forbid students from using their native languages and participating in their own cultural practices. Residential schools were largely run by Christian churches, operating in conjunction with Christian missions with minimal government oversight. The book, Stolen Lives: The Indigenous peoples of Canada and the Indian Residentials Schools, describes this form of operation: "The government provided little leadership, and the clergy in charge were left to decide what to teach and how to teach it. Their priority was to impart the teachings of their church or order—not to provide a good education that could help students in their post-graduation lives." In a New York Times op-ed, Gabrielle Scrimshaw describes her grandparents being forced to send her mother to one of these schools or risk imprisonment. After hiding her mother on "school pick up day" so as to avoid sending their daughter to institutions whose abuse was well known at the time (mid-20th century). Scrimshaw's mother was left with limited options for further education she says and is today illiterate as a result. Scrimshaw explains, "Seven generations of my ancestors went through these schools. Each new family member enrolled meant a compounding of abuse and a steady loss of identity, culture and hope. My mother was the last generation. the experience left her broken, and like so many, she turned to substances to numb these pains." A report, republished by CBC News, estimates nearly 6,000 children died in the care of these schools.
The colonisation of native peoples in North America remains active today despite the closing of the majority of residential schools. This form of cultural imperialism continues in the use of Native Americans as mascots for schools and athletic teams. Jason Edward Black, a professor and chair in the Department of Communication Studies at the University of North Carolina at Charlotte, describes how the use of Native Americans as mascots furthers the colonial attitudes of the 18th and 19th centuries.
Indigenous groups, along with cultural studies scholars, view the Native mascots as hegemonic devices–commodification tools–that advance a contemporary manifest destiny by marketing Native culture as Euromerican identity.
In Deciphering Pocahontas, Kent Ono and Derek Buescher wrote: "Euro-American culture has made a habit of appropriating, and redefining what is 'distinctive' and constitutive of Native Americans."
Cultural imperialism has also been used in connection with the expansion of German influence under the Nazis in the middle of the twentieth century. Alan Steinweis and Daniel Rogers note that even before the Nazis came to power, "Already in the Weimar Republic, German academic specialists on eastern Europe had contributed through their publications and teaching to the legitimization of German territorial revanchism and cultural imperialism. These scholars operated primarily in the disciplines of history, economics, geography, and literature." In the area of music, Michael Kater writes that during the WWII German occupation of France, Hans Rosbaud, a German conductor based by the Nazi regime in Strasbourg, became "at least nominally, a servant of Nazi cultural imperialism directed against the French."
In Italy during the war, Germany pursued "a European cultural front that gravitates around German culture". The Nazi propaganda minister Joseph Goebbels set up the European Union of Writers, "one of Goebbels's most ambitious projects for Nazi cultural hegemony. Presumably a means of gathering authors from Germany, Italy, and the occupied countries to plan the literary life of the new Europe, the union soon emerged as a vehicle of German cultural imperialism." For other parts of Europe, Robert Gerwarth, writing about cultural imperialism and Reinhard Heydrich, states that the "Nazis' Germanization project was based on a historically unprecedented programme of racial stock-taking, theft, expulsion and murder." Also, "The full integration of the [Czech] Protectorate into this New Order required the complete Germanization of the Protectorate's cultural life and the eradication of indigenous Czech and Jewish culture."
The actions by Nazi Germany reflect on the notion of race and culture playing a significant role in imperialism. The idea that there is a distinction between the Germans and the Jews has created the illusion of Germans believing they were superior to the Jewish inferiors, the notion of us/them and self/others.
Cultural imperialism manifests in the Western world in the form legal system to include commodification and marketing of indigenous resources (example medicinal, spiritual or artistic) and genetic resources (example human DNA).
The terms "McDonaldization", "Disneyization" and "Cocacolonization" have been coined to describe the spread of Western cultural influence.
There are many countries affected by the US and their pop-culture. For example, the film industry in Nigeria referred to as "Nollywood" being the second largest as it produces more films annually than the United States, their films are shown across Africa. Another term that describes the spread of Western cultural influence is "Hollywoodization" it is when American culture is promoted through Hollywood films which can culturally affect the viewers of Hollywood films. | [
{
"paragraph_id": 0,
"text": "Cultural imperialism (also cultural colonialism) comprises the cultural dimensions of imperialism. The word \"imperialism\" describes practices in which a country engages culture (language, tradition, and ritual, politics, economics) to create and maintain unequal social and economic relationships among social groups. Cultural imperialism often uses wealth, media power and violence to implement the system of cultural hegemony that legitimizes imperialism.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Cultural imperialism may take various forms, such as an attitude, a formal policy, or military action—insofar as each of these reinforces the empire's cultural hegemony. Research on the topic occurs in scholarly disciplines, and is especially prevalent in communication and media studies, education, foreign policy, history, international relations, linguistics, literature, post-colonialism, science, sociology, social theory, environmentalism, and sports.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Cultural imperialism may be distinguished from the natural process of cultural diffusion. The spread of culture around the world is referred to as cultural globalization.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Although the Oxford English Dictionary has a 1921 reference to the \"cultural imperialism of the Russians\", John Tomlinson, in his book on the subject, writes that the term emerged in the 1960s and has been a focus of research since at least the 1970s. Terms such as \"media imperialism\", \"structural imperialism\", \"cultural dependency and domination\", \"cultural synchronization\", \"electronic colonialism\", \"ideological imperialism\", and \"economic imperialism\" have all been used to describe the same basic notion of cultural imperialism.",
"title": "Background and definitions"
},
{
"paragraph_id": 4,
"text": "The term refers largely to the exercise of power in a cultural relationship in which the principles, ideas, practices, and values of a powerful, invading society are imposed upon indigenous cultures in the occupied areas. The process is often used to describe examples of when the compulsory practices of the cultural traditions of the imperial social group are implemented upon a conquered social group. The process is also present when powerful nations are able to flood the information and media space with their ideas, limiting countries and communities ability to compete and expose people to locally created content.",
"title": "Background and definitions"
},
{
"paragraph_id": 5,
"text": "Cultural imperialism has been called a process that intends to transition the \"cultural symbols of the invading communities from 'foreign' to 'natural,''domestic,'\" comments Jeffrey Herlihy-Mera. He described the process as being carried out in three phases by merchants, then the military, then politicians. While the third phase continues \"in perpetuity\", cultural imperialism tends to be \"gradual, contested (and continues to be contested), and is by nature incomplete. The partial and imperfect configuration of this ontology takes an implicit conceptualization of reality and attempts—and often fails—to elide other forms of collective existence.\" In order to achieve that end, cultural engineering projects strive to \"isolate residents within constructed spheres of symbols\" such that they (eventually, in some cases after several generations) abandon other cultures and identify with the new symbols. \"The broader intended outcome of these interventions might be described as a common recognition of possession of the land itself (on behalf of the organizations publishing and financing the images).\"",
"title": "Background and definitions"
},
{
"paragraph_id": 6,
"text": "For Herbert Schiller, cultural imperialism refers to the American Empire's \"coercive and persuasive agencies, and their capacity to promote and universalize an American 'way of life' in other countries without any reciprocation of influence.\" According to Schiller, cultural imperialism \"pressured, forced and bribed\" societies to integrate with the U.S.'s expansive capitalist model but also incorporated them with attraction and persuasion by winning \"the mutual consent, even solicitation of the indigenous rulers.\" He continues remarks that it is:",
"title": "Background and definitions"
},
{
"paragraph_id": 7,
"text": "the sum processes by which a society is brought into the modern [U.S.-centered] world system and how its dominating stratum is attracted, pressured, forced, and sometimes bribed into shaping social institutions to correspond to, or even promote, the values and structures of the dominating centres of the system. The public media are the foremost example of operating enterprises that are used in the penetrative process. For penetration on a significant scale the media themselves must be captured by the dominating/penetrating power. This occurs largely through the commercialization of broadcasting.",
"title": "Background and definitions"
},
{
"paragraph_id": 8,
"text": "The historical contexts, iterations, complexities, and politics of Schiller's foundational and substantive theorization of cultural imperialism in international communication and media studies are discussed in detail by political economy of communication researchers Richard Maxwell, Vincent Mosco, Graham Murdock, and Tanner Mirrlees.",
"title": "Background and definitions"
},
{
"paragraph_id": 9,
"text": "Downing and Sreberny-Mohammadi state: \"Cultural imperialism signifies the dimensions of the process that go beyond economic exploitation or military force. In the history of colonialism, (i.e., the form of imperialism in which the government of the colony is run directly by foreigners), the educational and media systems of many Third World countries have been set up as replicas of those in Britain, France, or the United States and carry their values. Western advertising has made further inroads, as have architectural and fashion styles. Subtly but powerfully, the message has often been insinuated that Western cultures are superior to the cultures of the Third World.\"",
"title": "Background and definitions"
},
{
"paragraph_id": 10,
"text": "In poststructuralist and postcolonial theory, cultural imperialism is often understood as the cultural legacy of Western colonialism, or forms of social action contributing to the continuation of Western hegemony. To some outside of the realm of this discourse, the term is critiqued as being unclear, unfocused, and/or contradictory in nature.",
"title": "Background and definitions"
},
{
"paragraph_id": 11,
"text": "The work of French philosopher and social theorist Michel Foucault has heavily influenced use of the term cultural imperialism, particularly his philosophical interpretation of power and his concept of governmentality. Following an interpretation of power similar to that of Machiavelli, Foucault defines power as immaterial, as a \"certain type of relation between individuals\" that has to do with complex strategic social positions that relate to the subject's ability to control its environment and influence those around itself. According to Foucault, power is intimately tied with his conception of truth. \"Truth\", as he defines it, is a \"system of ordered procedures for the production, regulation, distribution, circulation, and operation of statements\" which has a \"circular relation\" with systems of power. Therefore, inherent in systems of power, is always \"truth\", which is culturally specific, inseparable from ideology which often coincides with various forms of hegemony. Cultural imperialism may be an example of this.",
"title": "Background and definitions"
},
{
"paragraph_id": 12,
"text": "Foucault's interpretation of governance is also very important in constructing theories of transnational power structure. In his lectures at the Collège de France, Foucault often defines governmentality as the broad art of \"governing\", which goes beyond the traditional conception of governance in terms of state mandates, and into other realms such as governing \"a household, souls, children, a province, a convent, a religious order, a family\". This relates directly back to Machiavelli's treatise on how to retain political power at any cost, The Prince, and Foucault's aforementioned conceptions of truth and power. (i.e. various subjectivities are created through power relations that are culturally specific, which lead to various forms of culturally specific governmentality such as neoliberal governmentality.)",
"title": "Background and definitions"
},
{
"paragraph_id": 13,
"text": "Edward Saïd is a founding figure of postcolonialism, established with the book Orientalism (1978), a humanist critique of The Enlightenment, which criticises Western knowledge of \"The East\"—specifically the English and the French constructions of what is and what is not \"Oriental\". Whereby said \"knowledge\" then led to cultural tendencies towards a binary opposition of the Orient vs. the Occident, wherein one concept is defined in opposition to the other concept, and from which they emerge as of unequal value. In Culture and Imperialism (1993), the sequel to Orientalism, Saïd proposes that, despite the formal end of the \"age of empire\" after the Second World War (1939–1945), colonial imperialism left a cultural legacy to the (previously) colonised peoples, which remains in their contemporary civilisations; and that said American cultural imperialism is very influential in the international systems of power.",
"title": "Background and definitions"
},
{
"paragraph_id": 14,
"text": "In \"Can the Subaltern Speak?\" Gayatri Chakravorty Spivak critiques common representations in the West of the Sati, as being controlled by authors other than the participants (specifically English colonizers and Hindu leaders). Because of this, Spivak argues that the subaltern, referring to the communities that participate in the Sati, are not able to represent themselves through their own voice. Spivak says that cultural imperialism has the power to disqualify or erase the knowledge and mode of education of certain populations that are low on the social and economic hierarchy.",
"title": "Background and definitions"
},
{
"paragraph_id": 15,
"text": "In A Critique of Postcolonial Reason, Spivak argues that Western philosophy has a history of not only exclusion of the subaltern from discourse, but also does not allow them to occupy the space of a fully human subject.",
"title": "Background and definitions"
},
{
"paragraph_id": 16,
"text": "Cultural imperialism can refer to either the forced acculturation of a subject population, or to the voluntary embracing of a foreign culture by individuals who do so of their own free will. Since these are two very different referents, the validity of the term has been called into question.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 17,
"text": "Cultural influence can be seen by the \"receiving\" culture as either a threat to or an enrichment of its cultural identity. It seems therefore useful to distinguish between cultural imperialism as an (active or passive) attitude of superiority, and the position of a culture or group that seeks to complement its own cultural production, considered partly deficient, with imported products.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 18,
"text": "The imported products or services can themselves represent, or be associated with, certain values (such as consumerism). According to one argument, the \"receiving\" culture does not necessarily perceive this link, but instead absorbs the foreign culture passively through the use of the foreign goods and services. Due to its somewhat concealed, but very potent nature, this hypothetical idea is described by some experts as \"banal imperialism\". For example, it is argued that while \"American companies are accused of wanting to control 95 percent of the world's consumers\", \"cultural imperialism involves much more than simple consumer goods; it involved the dissemination of American principles such as freedom and democracy\", a process which \"may sound appealing\" but which \"masks a frightening truth: many cultures around the world are disappearing due to the overwhelming influence of corporate and cultural America\".",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 19,
"text": "Some believe that the newly globalised economy of the late 20th and early 21st century has facilitated this process through the use of new information technology. This kind of cultural imperialism is derived from what is called \"soft power\". The theory of electronic colonialism extends the issue to global cultural issues and the impact of major multi-media conglomerates, ranging from Paramount, WarnerMedia, AT&T, Disney, News Corp, to Google and Microsoft with the focus on the hegemonic power of these mainly United States-based communication giants.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 20,
"text": "One of the reasons often given for opposing any form of cultural imperialism, voluntary or otherwise, is the preservation of cultural diversity, a goal seen by some as analogous to the preservation of ecological diversity. Proponents of this idea argue either that such diversity is valuable in itself, to preserve human historical heritage and knowledge, or instrumentally valuable because it makes available more ways of solving problems and responding to catastrophes, natural or otherwise.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 21,
"text": "Of all the areas of the world that scholars have claimed to be adversely affected by imperialism, Africa is probably the most notable. In the expansive \"age of imperialism\" of the nineteenth century, scholars have argued that European colonisation in Africa has led to the elimination of many various cultures, worldviews, and epistemologies, particularly through neocolonisation of public education. This, arguably has led to uneven development, and further informal forms of social control having to do with culture and imperialism. A variety of factors, scholars argue, lead to the elimination of cultures, worldviews, and epistemologies, such as \"de-linguicization\" (replacing native African languages with European ones), devaluing ontologies that are not explicitly individualistic, and at times going as far as to not only define Western culture itself as science, but that non-Western approaches to science, the Arts, indigenous culture, etc. are not even knowledge. One scholar, Ali A. Abdi, claims that imperialism inherently \"involve[s] extensively interactive regimes and heavy contexts of identity deformation, misrecognition, loss of self-esteem, and individual and social doubt in self-efficacy.\" Therefore, all imperialism would always, already be cultural.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 22,
"text": "Neoliberalism is often critiqued by sociologists, anthropologists, and cultural studies scholars as being culturally imperialistic. Critics of neoliberalism, at times, claim that it is the newly predominant form of imperialism. Other scholars, such as Elizabeth Dunn and Julia Elyachar have claimed that neoliberalism requires and creates its own form of governmentality.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 23,
"text": "In Dunn's work, Privatizing Poland, she argues that the expansion of the multinational corporation, Gerber, into Poland in the 1990s imposed Western, neoliberal governmentality, ideologies, and epistemologies upon the post-soviet persons hired. Cultural conflicts occurred most notably the company's inherent individualistic policies, such as promoting competition among workers rather than cooperation, and in its strong opposition to what the company owners claimed was bribery.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 24,
"text": "In Elyachar's work, Markets of Dispossession, she focuses on ways in which, in Cairo, NGOs along with INGOs and the state promoted neoliberal governmentality through schemas of economic development that relied upon \"youth microentrepreneurs\". Youth microentrepreneurs would receive small loans to build their own businesses, similar to the way that microfinance supposedly operates. Elyachar argues though, that these programs not only were a failure, but that they shifted cultural opinions of value (personal and cultural) in a way that favoured Western ways of thinking and being.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 25,
"text": "Often, methods of promoting development and social justice are critiqued as being imperialistic in a cultural sense. For example, Chandra Mohanty has critiqued Western feminism, claiming that it has created a misrepresentation of the \"third world woman\" as being completely powerless, unable to resist male dominance. Thus, this leads to the often critiqued narrative of the \"white man\" saving the \"brown woman\" from the \"brown man\". Other, more radical critiques of development studies, have to do with the field of study itself. Some scholars even question the intentions of those developing the field of study, claiming that efforts to \"develop\" the Global South were never about the South itself. Instead, these efforts, it is argued, were made in order to advance Western development and reinforce Western hegemony.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 26,
"text": "The core of cultural imperialism thesis is integrated with the political-economy traditional approach in media effects research. Critics of cultural imperialism commonly claim that non-Western cultures, particularly from the Third World, will forsake their traditional values and lose their cultural identities when they are solely exposed to Western media. Nonetheless, Michael B. Salwen, in his book Critical Studies in Mass Communication (1991), claims that cross-consideration and integration of empirical findings on cultural imperialist influences is very critical in terms of understanding mass media in the international sphere. He recognises both of contradictory contexts on cultural imperialist impacts. The first context is where cultural imperialism imposes socio-political disruptions on developing nations. Western media can distort images of foreign cultures and provoke personal and social conflicts to developing nations in some cases. Another context is that peoples in developing nations resist to foreign media and preserve their cultural attitudes. Although he admits that outward manifestations of Western culture may be adopted, but the fundamental values and behaviours remain still. Furthermore, positive effects might occur when male-dominated cultures adopt the \"liberation\" of women with exposure to Western media and it stimulates ample exchange of cultural exchange.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 27,
"text": "Critics of scholars who discuss cultural imperialism have a number of critiques. Cultural imperialism is a term that is only used in discussions where cultural relativism and constructivism are generally taken as true. (One cannot critique promoting Western values if one believes that said values are good. Similarly, one cannot argue that Western epistemology is unjustly promoted in non-Western societies if one believes that those epistemologies are good.) Therefore, those who disagree with cultural relativism and/or constructivism may critique the employment of the term, cultural imperialism on those terms.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 28,
"text": "John Tomlinson provides a critique of cultural imperialism theory and reveals major problems in the way in which the idea of cultural, as opposed to economic or political, imperialism is formulated. In his book Cultural Imperialism: A Critical Introduction, he delves into the much debated \"media imperialism\" theory. Summarizing research on the Third World's reception of American television shows, he challenges the cultural imperialism argument, conveying his doubts about the degree to which US shows in developing nations actually carry US values and improve the profits of US companies. Tomlinson suggests that cultural imperialism is growing in some respects, but local transformation and interpretations of imported media products propose that cultural diversification is not at an end in global society. He explains that one of the fundamental conceptual mistakes of cultural imperialism is to take for granted that the distribution of cultural goods can be considered as cultural dominance. He thus supports his argument highly criticising the concept that Americanization is occurring through global overflow of American television products. He points to a myriad of examples of television networks who have managed to dominate their domestic markets and that domestic programs generally top the ratings. He also doubts the concept that cultural agents are passive receivers of information. He states that movement between cultural/geographical areas always involves translation, mutation, adaptation, and the creation of hybridity.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 29,
"text": "Other key critiques are that the term is not defined well, and employs further terms that are not defined well, and therefore lacks explanatory power, that cultural imperialism is hard to measure, and that the theory of a legacy of colonialism is not always true.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 30,
"text": "David Rothkopf, managing director of Kissinger Associates and an adjunct professor of international affairs at Columbia University (who also served as a senior U.S. Commerce Department official in the Clinton Administration), wrote about cultural imperialism in his provocatively titled In Praise of Cultural Imperialism? in the summer 1997 issue of Foreign Policy magazine. Rothkopf says that the United States should embrace \"cultural imperialism\" as in its self-interest. But his definition of cultural imperialism stresses spreading the values of tolerance and openness to cultural change in order to avoid war and conflict between cultures as well as expanding accepted technological and legal standards to provide free traders with enough security to do business with more countries. Rothkopf's definition almost exclusively involves allowing individuals in other nations to accept or reject foreign cultural influences. He also mentions, but only in passing, the use of the English language and consumption of news and popular music and film as cultural dominance that he supports. Rothkopf additionally makes the point that globalisation and the Internet are accelerating the process of cultural influence.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 31,
"text": "Culture is sometimes used by the organisers of society—politicians, theologians, academics, and families—to impose and ensure order, the rudiments of which change over time as need dictates. One need only look at the 20th century's genocides. In each one, leaders used culture as a political front to fuel the passions of their armies and other minions and to justify their actions among their people.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 32,
"text": "Rothkopf then cites genocide and massacres in Armenia, Russia, the Holocaust, Cambodia, Bosnia and Herzegovina, Rwanda and East Timor as examples of culture (in some cases expressed in the ideology of \"political culture\" or religion) being misused to justify violence. He also acknowledges that cultural imperialism in the past has been guilty of forcefully eliminating the cultures of natives in the Americas and in Africa, or through use of the Inquisition, \"and during the expansion of virtually every empire.\" The most important way to deal with cultural influence in any nation, according to Rothkopf, is to promote tolerance and allow, or even promote, cultural diversities that are compatible with tolerance and to eliminate those cultural differences that cause violent conflict:",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 33,
"text": "Cultural dominance can also be seen in the 1930s in Australia where the Aboriginal Assimilation Policy acted as an attempt to wipe out the Native Australian people. The British settlers tried to biologically alter the skin colour of the Australian Aboriginal people through mixed breeding with white people. The policy also made attempts to forcefully conform the Aborigines to western ideas of dress and education.",
"title": "Contemporary ideas and debate"
},
{
"paragraph_id": 34,
"text": "Although the term was popularised in the 1960s, and was used by its original proponents to refer to cultural hegemonies in a post-colonial world, cultural imperialism has also been used to refer to times further in the past.",
"title": "In history"
},
{
"paragraph_id": 35,
"text": "The Ancient Greeks are known for spreading their culture around the Mediterranean and Near East through trade and conquest. During the Archaic Period, the burgeoning Greek city-states established settlements and colonies across the Mediterranean Sea, especially in Sicily and southern Italy, influencing the Etruscan and Roman peoples of the region. In the late fourth century BC, Alexander the Great conquered Persian and Indian territories all the way to the Indus River Valley and Punjab, spreading Greek pagan religion, art, and science along the way. This resulted in the rise of Hellenistic kingdoms and cities across Egypt, the Near East, Central Asia, and Northwest India where Greek culture fused with the cultures of the indigenous peoples. The Greek influence prevailed even longer in science and literature, where medieval Muslim scholars in the Middle East studied the writings of Aristotle for scientific learning.",
"title": "In history"
},
{
"paragraph_id": 36,
"text": "The Roman Empire was also an early example of cultural imperialism. Early Rome, in its conquest of Italy, assimilated the people of Etruria by replacing the Etruscan language with Latin, which led to the demise of that language and many aspects of Etruscan civilisation. Cultural Romanization was imposed on many parts of Rome's empire by \"many regions receiving Roman culture unwillingly, as a form of cultural imperialism.\" For example, when Greece was conquered by the Roman armies, Rome set about altering the culture of Greece to conform with Roman ideals. For instance, the Greek habit of stripping naked, in public, for exercise, was looked on askance by Roman writers, who considered the practice to be a cause of the Greeks' effeminacy and enslavement. The Roman example has been linked to modern instances of European imperialism in African countries, bridging the two instances with Slavoj Zizek's discussions of 'empty signifiers'. The Pax Romana was secured in the empire, in part, by the \"forced acculturation of the culturally diverse populations that Rome had conquered.\"",
"title": "In history"
},
{
"paragraph_id": 37,
"text": "British worldwide expansion in the 18th and 19th centuries was an economic and political phenomenon. However, \"there was also a strong social and cultural dimension to it, which Rudyard Kipling termed the 'white man's burden'.\" One of the ways this was carried out was by religious proselytising, by, amongst others, the London Missionary Society, which was \"an agent of British cultural imperialism.\" Another way, was by the imposition of educational material on the colonies for an \"imperial curriculum\". Robin A. Butlin writes, \"The promotion of empire through books, illustrative materials, and educational syllabuses was widespread, part of an education policy geared to cultural imperialism\". This was also true of science and technology in the empire. Douglas M. Peers and Nandini Gooptu note that \"Most scholars of colonial science in India now prefer to stress the ways in which science and technology worked in the service of colonialism, as both a 'tool of empire' in the practical sense and as a vehicle for cultural imperialism. In other words, science developed in India in ways that reflected colonial priorities, tending to benefit Europeans at the expense of Indians, while remaining dependent on and subservient to scientific authorities in the colonial metropolis.\" British sports were spread across the Empire partially as a way of encouraging British values and cultural uniformity, though this was tempered by the fact that colonised peoples gained a sense of nationalistic pride by defeating the British in their own sports.",
"title": "In history"
},
{
"paragraph_id": 38,
"text": "The analysis of cultural imperialism carried out by Edward Said drew principally from a study of the British Empire. According to Danilo Raponi, the cultural imperialism of the British in the 19th century had a much wider effect than only in the British Empire. He writes, \"To paraphrase Said, I see cultural imperialism as a complex cultural hegemony of a country, Great Britain, that in the 19th century had no rivals in terms of its ability to project its power across the world and to influence the cultural, political and commercial affairs of most countries. It is the 'cultural hegemony' of a country whose power to export the most fundamental ideas and concepts at the basis of its understanding of 'civilisation' knew practically no bounds.\" In this, for example, Raponi includes Italy.",
"title": "In history"
},
{
"paragraph_id": 39,
"text": "The New Cambridge Modern History writes about the cultural imperialism of Napoleonic France. Napoleon used the Institut de France \"as an instrument for transmuting French universalism into cultural imperialism.\" Members of the Institute (who included Napoleon), descended upon Egypt in 1798. \"Upon arrival they organised themselves into an Institute of Cairo. The Rosetta Stone is their most famous find. The science of Egyptology is their legacy.\"",
"title": "In history"
},
{
"paragraph_id": 40,
"text": "After the First World War, Germans were worried about the extent of French influence in the annexed Rhineland, with the French occupation of the Ruhr Valley in 1923. An early use of the term appeared in an essay by Paul Ruhlmann (as \"Peter Hartmann\") at that date, entitled French Cultural Imperialism on the Rhine.",
"title": "In history"
},
{
"paragraph_id": 41,
"text": "Keeping in line with the trends of international imperialistic endeavours, the expansion of Canadian and American territory in the 19th century saw cultural imperialism employed as a means of control over indigenous populations. This, when used in conjunction of more traditional forms of ethnic cleansing and genocide in the United States, saw devastating, lasting effects on indigenous communities.",
"title": "In history"
},
{
"paragraph_id": 42,
"text": "In 2017 Canada celebrated its 150-year anniversary of the confederating of three British colonies. As Catherine Murton Stoehr points out in Origins, a publication organised by the history departments of Ohio State University and Miami University, the occasion came with remembrance of Canada's treatment of First Nations people.",
"title": "In history"
},
{
"paragraph_id": 43,
"text": "A mere 9 years after the 1867 signing of confederation Canada passed \"The Indian Act\", a separate and not equal form of government especially for First Nations. The Indian Act remains in place today, confining and constraining Indigenous jurisdiction in every area of life, in direct contravention of the nation's founding treaties with indigenous nations.",
"title": "In history"
},
{
"paragraph_id": 44,
"text": "Numerous policies focused on indigenous persons came into effect shortly thereafter. Most notable is the use of residential schools across Canada as a means to remove indigenous persons from their culture and instill in them the beliefs and values of the majorised colonial hegemony. The policies of these schools, as described by Ward Churchill in his book Kill the Indian, Save the Man, were to forcefully assimilate students who were often removed with force from their families. These schools forbid students from using their native languages and participating in their own cultural practices. Residential schools were largely run by Christian churches, operating in conjunction with Christian missions with minimal government oversight. The book, Stolen Lives: The Indigenous peoples of Canada and the Indian Residentials Schools, describes this form of operation: \"The government provided little leadership, and the clergy in charge were left to decide what to teach and how to teach it. Their priority was to impart the teachings of their church or order—not to provide a good education that could help students in their post-graduation lives.\" In a New York Times op-ed, Gabrielle Scrimshaw describes her grandparents being forced to send her mother to one of these schools or risk imprisonment. After hiding her mother on \"school pick up day\" so as to avoid sending their daughter to institutions whose abuse was well known at the time (mid-20th century). Scrimshaw's mother was left with limited options for further education she says and is today illiterate as a result. Scrimshaw explains, \"Seven generations of my ancestors went through these schools. Each new family member enrolled meant a compounding of abuse and a steady loss of identity, culture and hope. My mother was the last generation. the experience left her broken, and like so many, she turned to substances to numb these pains.\" A report, republished by CBC News, estimates nearly 6,000 children died in the care of these schools.",
"title": "In history"
},
{
"paragraph_id": 45,
"text": "The colonisation of native peoples in North America remains active today despite the closing of the majority of residential schools. This form of cultural imperialism continues in the use of Native Americans as mascots for schools and athletic teams. Jason Edward Black, a professor and chair in the Department of Communication Studies at the University of North Carolina at Charlotte, describes how the use of Native Americans as mascots furthers the colonial attitudes of the 18th and 19th centuries.",
"title": "In history"
},
{
"paragraph_id": 46,
"text": "Indigenous groups, along with cultural studies scholars, view the Native mascots as hegemonic devices–commodification tools–that advance a contemporary manifest destiny by marketing Native culture as Euromerican identity.",
"title": "In history"
},
{
"paragraph_id": 47,
"text": "In Deciphering Pocahontas, Kent Ono and Derek Buescher wrote: \"Euro-American culture has made a habit of appropriating, and redefining what is 'distinctive' and constitutive of Native Americans.\"",
"title": "In history"
},
{
"paragraph_id": 48,
"text": "Cultural imperialism has also been used in connection with the expansion of German influence under the Nazis in the middle of the twentieth century. Alan Steinweis and Daniel Rogers note that even before the Nazis came to power, \"Already in the Weimar Republic, German academic specialists on eastern Europe had contributed through their publications and teaching to the legitimization of German territorial revanchism and cultural imperialism. These scholars operated primarily in the disciplines of history, economics, geography, and literature.\" In the area of music, Michael Kater writes that during the WWII German occupation of France, Hans Rosbaud, a German conductor based by the Nazi regime in Strasbourg, became \"at least nominally, a servant of Nazi cultural imperialism directed against the French.\"",
"title": "In history"
},
{
"paragraph_id": 49,
"text": "In Italy during the war, Germany pursued \"a European cultural front that gravitates around German culture\". The Nazi propaganda minister Joseph Goebbels set up the European Union of Writers, \"one of Goebbels's most ambitious projects for Nazi cultural hegemony. Presumably a means of gathering authors from Germany, Italy, and the occupied countries to plan the literary life of the new Europe, the union soon emerged as a vehicle of German cultural imperialism.\" For other parts of Europe, Robert Gerwarth, writing about cultural imperialism and Reinhard Heydrich, states that the \"Nazis' Germanization project was based on a historically unprecedented programme of racial stock-taking, theft, expulsion and murder.\" Also, \"The full integration of the [Czech] Protectorate into this New Order required the complete Germanization of the Protectorate's cultural life and the eradication of indigenous Czech and Jewish culture.\"",
"title": "In history"
},
{
"paragraph_id": 50,
"text": "The actions by Nazi Germany reflect on the notion of race and culture playing a significant role in imperialism. The idea that there is a distinction between the Germans and the Jews has created the illusion of Germans believing they were superior to the Jewish inferiors, the notion of us/them and self/others.",
"title": "In history"
},
{
"paragraph_id": 51,
"text": "Cultural imperialism manifests in the Western world in the form legal system to include commodification and marketing of indigenous resources (example medicinal, spiritual or artistic) and genetic resources (example human DNA).",
"title": "In history"
},
{
"paragraph_id": 52,
"text": "The terms \"McDonaldization\", \"Disneyization\" and \"Cocacolonization\" have been coined to describe the spread of Western cultural influence.",
"title": "In history"
},
{
"paragraph_id": 53,
"text": "There are many countries affected by the US and their pop-culture. For example, the film industry in Nigeria referred to as \"Nollywood\" being the second largest as it produces more films annually than the United States, their films are shown across Africa. Another term that describes the spread of Western cultural influence is \"Hollywoodization\" it is when American culture is promoted through Hollywood films which can culturally affect the viewers of Hollywood films.",
"title": "In history"
}
] | Cultural imperialism comprises the cultural dimensions of imperialism. The word "imperialism" describes practices in which a country engages culture to create and maintain unequal social and economic relationships among social groups. Cultural imperialism often uses wealth, media power and violence to implement the system of cultural hegemony that legitimizes imperialism. Cultural imperialism may take various forms, such as an attitude, a formal policy, or military action—insofar as each of these reinforces the empire's cultural hegemony. Research on the topic occurs in scholarly disciplines, and is especially prevalent in communication and media studies, education, foreign policy, history, international relations, linguistics, literature, post-colonialism, science, sociology, social theory, environmentalism, and sports. Cultural imperialism may be distinguished from the natural process of cultural diffusion. The spread of culture around the world is referred to as cultural globalization. | 2001-10-19T13:48:57Z | 2023-12-07T15:50:00Z | [
"Template:Col div",
"Template:Cite book",
"Template:Cbignore",
"Template:Culture",
"Template:Short description",
"Template:Use dmy dates",
"Template:Blockquote",
"Template:Michel Foucault",
"Template:Relevance inline",
"Template:Main",
"Template:Anli",
"Template:Colend",
"Template:Cite web",
"Template:Citation",
"Template:Authority control",
"Template:'\"",
"Template:Globalize",
"Template:Further",
"Template:Reflist",
"Template:Cite journal",
"Template:Webarchive",
"Template:Cite news"
] | https://en.wikipedia.org/wiki/Cultural_imperialism |
6,271 | Chemical reaction | A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.
The substance (or substances) initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise course of action is part of the reaction mechanism. Chemical reactions are described with chemical equations, which symbolically present the starting materials, end products, and sometimes intermediate products and reaction conditions.
Chemical reactions happen at a characteristic reaction rate at a given temperature and chemical concentration. Typically, reaction rates increase with increasing temperature because there is more thermal energy available to reach the activation energy necessary for breaking bonds between atoms.
A reaction may be classified as redox in which oxidation and reduction occur or non-redox in which there is no oxidation and reduction occurring. Most simple redox reactions may be classified as a combination, decomposition, or single displacement reaction.
Different chemical reactions are used during chemical synthesis in order to obtain the desired product. In biochemistry, a consecutive series of chemical reactions (where the product of one reaction is the reactant of the next reaction) form metabolic pathways. These reactions are often catalyzed by protein enzymes. Enzymes increase the rates of biochemical reactions, so that metabolic syntheses and decompositions impossible under ordinary conditions can occur at the temperature and concentrations present within a cell.
The general concept of a chemical reaction has been extended to reactions between entities smaller than atoms, including nuclear reactions, radioactive decays and reactions between elementary particles, as described by quantum field theory.
Chemical reactions such as combustion in fire, fermentation and the reduction of ores to metals were known since antiquity. Initial theories of transformation of materials were developed by Greek philosophers, such as the Four-Element Theory of Empedocles stating that any substance is composed of the four basic elements – fire, water, air and earth. In the Middle Ages, chemical transformations were studied by alchemists. They attempted, in particular, to convert lead into gold, for which purpose they used reactions of lead and lead-copper alloys with sulfur.
The artificial production of chemical substances already was a central goal for medieval alchemists. Examples include the synthesis of ammonium chloride from organic substances as described in the works (c. 850–950) attributed to Jābir ibn Ḥayyān, or the production of mineral acids such as sulfuric and nitric acids by later alchemists, starting from c. 1300. The production of mineral acids involved the heating of sulfate and nitrate minerals such as copper sulfate, alum and saltpeter. In the 17th century, Johann Rudolph Glauber produced hydrochloric acid and sodium sulfate by reacting sulfuric acid and sodium chloride. With the development of the lead chamber process in 1746 and the Leblanc process, allowing large-scale production of sulfuric acid and sodium carbonate, respectively, chemical reactions became implemented into the industry. Further optimization of sulfuric acid technology resulted in the contact process in the 1880s, and the Haber process was developed in 1909–1910 for ammonia synthesis.
From the 16th century, researchers including Jan Baptist van Helmont, Robert Boyle, and Isaac Newton tried to establish theories of experimentally observed chemical transformations. The phlogiston theory was proposed in 1667 by Johann Joachim Becher. It postulated the existence of a fire-like element called "phlogiston", which was contained within combustible bodies and released during combustion. This proved to be false in 1785 by Antoine Lavoisier who found the correct explanation of the combustion as a reaction with oxygen from the air.
Joseph Louis Gay-Lussac recognized in 1808 that gases always react in a certain relationship with each other. Based on this idea and the atomic theory of John Dalton, Joseph Proust had developed the law of definite proportions, which later resulted in the concepts of stoichiometry and chemical equations.
Regarding the organic chemistry, it was long believed that compounds obtained from living organisms were too complex to be obtained synthetically. According to the concept of vitalism, organic matter was endowed with a "vital force" and distinguished from inorganic materials. This separation was ended however by the synthesis of urea from inorganic precursors by Friedrich Wöhler in 1828. Other chemists who brought major contributions to organic chemistry include Alexander William Williamson with his synthesis of ethers and Christopher Kelk Ingold, who, among many discoveries, established the mechanisms of substitution reactions.
The general characteristics of chemical reactions are:
Chemical equations are used to graphically illustrate chemical reactions. They consist of chemical or structural formulas of the reactants on the left and those of the products on the right. They are separated by an arrow (→) which indicates the direction and type of the reaction; the arrow is read as the word "yields". The tip of the arrow points in the direction in which the reaction proceeds. A double arrow (⇌) pointing in opposite directions is used for equilibrium reactions. Equations should be balanced according to the stoichiometry, the number of atoms of each species should be the same on both sides of the equation. This is achieved by scaling the number of involved molecules (A, B, C and D in a schematic example below) by the appropriate integers a, b, c and d.
More elaborate reactions are represented by reaction schemes, which in addition to starting materials and products show important intermediates or transition states. Also, some relatively minor additions to the reaction can be indicated above the reaction arrow; examples of such additions are water, heat, illumination, a catalyst, etc. Similarly, some minor products can be placed below the arrow, often with a minus sign.
Retrosynthetic analysis can be applied to design a complex synthesis reaction. Here the analysis starts from the products, for example by splitting selected chemical bonds, to arrive at plausible initial reagents. A special arrow (⇒) is used in retro reactions.
The elementary reaction is the smallest division into which a chemical reaction can be decomposed, it has no intermediate products. Most experimentally observed reactions are built up from many elementary reactions that occur in parallel or sequentially. The actual sequence of the individual elementary reactions is known as reaction mechanism. An elementary reaction involves a few molecules, usually one or two, because of the low probability for several molecules to meet at a certain time.
The most important elementary reactions are unimolecular and bimolecular reactions. Only one molecule is involved in a unimolecular reaction; it is transformed by isomerization or a dissociation into one or more other molecules. Such reactions require the addition of energy in the form of heat or light. A typical example of a unimolecular reaction is the cis–trans isomerization, in which the cis-form of a compound converts to the trans-form or vice versa.
In a typical dissociation reaction, a bond in a molecule splits (ruptures) resulting in two molecular fragments. The splitting can be homolytic or heterolytic. In the first case, the bond is divided so that each product retains an electron and becomes a neutral radical. In the second case, both electrons of the chemical bond remain with one of the products, resulting in charged ions. Dissociation plays an important role in triggering chain reactions, such as hydrogen–oxygen or polymerization reactions.
For bimolecular reactions, two molecules collide and react with each other. Their merger is called chemical synthesis or an addition reaction.
Another possibility is that only a portion of one molecule is transferred to the other molecule. This type of reaction occurs, for example, in redox and acid-base reactions. In redox reactions, the transferred particle is an electron, whereas in acid-base reactions it is a proton. This type of reaction is also called metathesis.
for example
Most chemical reactions are reversible; that is, they can and do run in both directions. The forward and reverse reactions are competing with each other and differ in reaction rates. These rates depend on the concentration and therefore change with the time of the reaction: the reverse rate gradually increases and becomes equal to the rate of the forward reaction, establishing the so-called chemical equilibrium. The time to reach equilibrium depends on parameters such as temperature, pressure, and the materials involved, and is determined by the minimum free energy. In equilibrium, the Gibbs free energy must be zero. The pressure dependence can be explained with the Le Chatelier's principle. For example, an increase in pressure due to decreasing volume causes the reaction to shift to the side with fewer moles of gas.
The reaction yield stabilizes at equilibrium but can be increased by removing the product from the reaction mixture or changed by increasing the temperature or pressure. A change in the concentrations of the reactants does not affect the equilibrium constant but does affect the equilibrium position.
Chemical reactions are determined by the laws of thermodynamics. Reactions can proceed by themselves if they are exergonic, that is if they release free energy. The associated free energy change of the reaction is composed of the changes of two different thermodynamic quantities, enthalpy and entropy:
Reactions can be exothermic, where ΔH is negative and energy is released. Typical examples of exothermic reactions are combustion, precipitation and crystallization, in which ordered solids are formed from disordered gaseous or liquid phases. In contrast, in endothermic reactions, heat is consumed from the environment. This can occur by increasing the entropy of the system, often through the formation of gaseous or dissolved reaction products, which have higher entropy. Since the entropy term in the free-energy change increases with temperature, many endothermic reactions preferably take place at high temperatures. On the contrary, many exothermic reactions such as crystallization occur preferably at lower temperatures. A change in temperature can sometimes reverse the sign of the enthalpy of a reaction, as for the carbon monoxide reduction of molybdenum dioxide:
This reaction to form carbon dioxide and molybdenum is endothermic at low temperatures, becoming less so with increasing temperature. ΔH° is zero at 1855 K, and the reaction becomes exothermic above that temperature.
Changes in temperature can also reverse the direction tendency of a reaction. For example, the water gas shift reaction
is favored by low temperatures, but its reverse is favored by high temperatures. The shift in reaction direction tendency occurs at 1100 K.
Reactions can also be characterized by their internal energy change, which takes into account changes in the entropy, volume and chemical potentials. The latter depends, among other things, on the activities of the involved substances.
The speed at which reactions take place is studied by reaction kinetics. The rate depends on various parameters, such as:
Several theories allow calculating the reaction rates at the molecular level. This field is referred to as reaction dynamics. The rate v of a first-order reaction, which could be the disintegration of a substance A, is given by:
Its integration yields:
Here k is the first-order rate constant, having dimension 1/time, [A](t) is the concentration at a time t and [A]0 is the initial concentration. The rate of a first-order reaction depends only on the concentration and the properties of the involved substance, and the reaction itself can be described with a characteristic half-life. More than one time constant is needed when describing reactions of higher order. The temperature dependence of the rate constant usually follows the Arrhenius equation:
where Ea is the activation energy and kB is the Boltzmann constant. One of the simplest models of reaction rate is the collision theory. More realistic models are tailored to a specific problem and include the transition state theory, the calculation of the potential energy surface, the Marcus theory and the Rice–Ramsperger–Kassel–Marcus (RRKM) theory.
In a synthesis reaction, two or more simple substances combine to form a more complex substance. These reactions are in the general form:
Two or more reactants yielding one product is another way to identify a synthesis reaction. One example of a synthesis reaction is the combination of iron and sulfur to form iron(II) sulfide:
Another example is simple hydrogen gas combined with simple oxygen gas to produce a more complex substance, such as water.
A decomposition reaction is when a more complex substance breaks down into its more simple parts. It is thus the opposite of a synthesis reaction and can be written as
One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas:
In a single displacement reaction, a single uncombined element replaces another in a compound; in other words, one element trades places with another element in a compound These reactions come in the general form of:
One example of a single displacement reaction is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas:
In a double displacement reaction, the anions and cations of two compounds switch places and form two entirely different compounds. These reactions are in the general form:
For example, when barium chloride (BaCl2) and magnesium sulfate (MgSO4) react, the SO4 anion switches places with the 2Cl anion, giving the compounds BaSO4 and MgCl2.
Another example of a double displacement reaction is the reaction of lead(II) nitrate with potassium iodide to form lead(II) iodide and potassium nitrate:
According to Le Châtelier's Principle, reactions may proceed in the forward or reverse direction until they end or reach equilibrium.
Reactions that proceed in the forward direction to approach equilibrium are often called spontaneous reactions, that is, Δ G {\displaystyle \Delta G} is negative, which means that if they occur at constant temperature and pressure, they decrease the Gibbs free energy of the reaction. They don't require much energy to proceed in the forward direction. Most reactions are forward reactions. Examples:
Reactions that proceed in the backward direction to approach equilibrium are often called non-spontaneous reactions, that is, Δ G {\displaystyle \Delta G} is positive, which means that if they occur at constant temperature and pressure, they increase the Gibbs free energy of the reaction. They require input of energy to proceed in the forward direction. Examples include:
In a combustion reaction, an element or compound reacts with an oxidant, usually oxygen, often producing energy in the form of heat or light. Combustion reactions frequently involve a hydrocarbon. For instance, the combustion of 1 mole (114 g) of octane in oxygen
releases 5500 kJ. A combustion reaction can also result from carbon, magnesium or sulfur reacting with oxygen.
Redox reactions can be understood in terms of the transfer of electrons from one involved species (reducing agent) to another (oxidizing agent). In this process, the former species is oxidized and the latter is reduced. Though sufficient for many purposes, these descriptions are not precisely correct. Oxidation is better defined as an increase in oxidation state of atoms and reduction as a decrease in oxidation state. In practice, the transfer of electrons will always change the oxidation state, but there are many reactions that are classed as "redox" even though no electron transfer occurs (such as those involving covalent bonds).
In the following redox reaction, hazardous sodium metal reacts with toxic chlorine gas to form the ionic compound sodium chloride, or common table salt:
In the reaction, sodium metal goes from an oxidation state of 0 (as it is a pure element) to +1: in other words, the sodium lost one electron and is said to have been oxidized. On the other hand, the chlorine gas goes from an oxidation of 0 (it is also a pure element) to −1: the chlorine gains one electron and is said to have been reduced. Because the chlorine is the one reduced, it is considered the electron acceptor, or in other words, induces oxidation in the sodium – thus the chlorine gas is considered the oxidizing agent. Conversely, the sodium is oxidized or is the electron donor, and thus induces a reduction in the other species and is considered the reducing agent.
Which of the involved reactants would be a reducing or oxidizing agent can be predicted from the electronegativity of their elements. Elements with low electronegativities, such as most metals, easily donate electrons and oxidize – they are reducing agents. On the contrary, many oxides or ions with high oxidation numbers of their non-oxygen atoms, such as H2O2, MnO4, CrO3, Cr2O7, or OsO4, can gain one or two extra electrons and are strong oxidizing agents.
For some main-group elements the number of electrons donated or accepted in a redox reaction can be predicted from the electron configuration of the reactant element. Elements try to reach the low-energy noble gas configuration, and therefore alkali metals and halogens will donate and accept one electron, respectively. Noble gases themselves are chemically inactive.
The overall redox reaction can be balanced by combining the oxidation and reduction half-reactions multiplied by coefficients such that the number of electrons lost in the oxidation equals the number of electrons gained in the reduction.
An important class of redox reactions are the electrolytic electrochemical reactions, where electrons from the power supply at the negative electrode are used as the reducing agent and electron withdrawal at the positive electrode as the oxidizing agent. These reactions are particularly important for the production of chemical elements, such as chlorine or aluminium. The reverse process, in which electrons are released in redox reactions and chemical energy is converted to electrical energy, is possible and used in batteries.
In complexation reactions, several ligands react with a metal atom to form a coordination complex. This is achieved by providing lone pairs of the ligand into empty orbitals of the metal atom and forming dipolar bonds. The ligands are Lewis bases, they can be both ions and neutral molecules, such as carbon monoxide, ammonia or water. The number of ligands that react with a central metal atom can be found using the 18-electron rule, saying that the valence shells of a transition metal will collectively accommodate 18 electrons, whereas the symmetry of the resulting complex can be predicted with the crystal field theory and ligand field theory. Complexation reactions also include ligand exchange, in which one or more ligands are replaced by another, and redox processes which change the oxidation state of the central metal atom.
In the Brønsted–Lowry acid–base theory, an acid–base reaction involves a transfer of protons (H) from one species (the acid) to another (the base). When a proton is removed from an acid, the resulting species is termed that acid's conjugate base. When the proton is accepted by a base, the resulting species is termed that base's conjugate acid. In other words, acids act as proton donors and bases act as proton acceptors according to the following equation:
The reverse reaction is possible, and thus the acid/base and conjugated base/acid are always in equilibrium. The equilibrium is determined by the acid and base dissociation constants (Ka and Kb) of the involved substances. A special case of the acid-base reaction is the neutralization where an acid and a base, taken at the exact same amounts, form a neutral salt.
Acid-base reactions can have different definitions depending on the acid-base concept employed. Some of the most common are:
Precipitation is the formation of a solid in a solution or inside another solid during a chemical reaction. It usually takes place when the concentration of dissolved ions exceeds the solubility limit and forms an insoluble salt. This process can be assisted by adding a precipitating agent or by the removal of the solvent. Rapid precipitation results in an amorphous or microcrystalline residue and a slow process can yield single crystals. The latter can also be obtained by recrystallization from microcrystalline salts.
Reactions can take place between two solids. However, because of the relatively small diffusion rates in solids, the corresponding chemical reactions are very slow in comparison to liquid and gas phase reactions. They are accelerated by increasing the reaction temperature and finely dividing the reactant to increase the contacting surface area.
The reaction can take place at the solid|gas interface, surfaces at very low pressure such as ultra-high vacuum. Via scanning tunneling microscopy, it is possible to observe reactions at the solid|gas interface in real space, if the time scale of the reaction is in the correct range. Reactions at the solid|gas interface are in some cases related to catalysis.
In photochemical reactions, atoms and molecules absorb energy (photons) of the illumination light and convert it into an excited state. They can then release this energy by breaking chemical bonds, thereby producing radicals. Photochemical reactions include hydrogen–oxygen reactions, radical polymerization, chain reactions and rearrangement reactions.
Many important processes involve photochemistry. The premier example is photosynthesis, in which most plants use solar energy to convert carbon dioxide and water into glucose, disposing of oxygen as a side-product. Humans rely on photochemistry for the formation of vitamin D, and vision is initiated by a photochemical reaction of rhodopsin. In fireflies, an enzyme in the abdomen catalyzes a reaction that results in bioluminescence. Many significant photochemical reactions, such as ozone formation, occur in the Earth atmosphere and constitute atmospheric chemistry.
In catalysis, the reaction does not proceed directly, but through a reaction with a third substance known as catalyst. Although the catalyst takes part in the reaction, forming weak bonds with reactants or intermediates, it is returned to its original state by the end of the reaction and so is not consumed. However, it can be inhibited, deactivated or destroyed by secondary processes. Catalysts can be used in a different phase (heterogeneous) or in the same phase (homogeneous) as the reactants. In heterogeneous catalysis, typical secondary processes include coking where the catalyst becomes covered by polymeric side products. Additionally, heterogeneous catalysts can dissolve into the solution in a solid-liquid system or evaporate in a solid–gas system. Catalysts can only speed up the reaction – chemicals that slow down the reaction are called inhibitors. Substances that increase the activity of catalysts are called promoters, and substances that deactivate catalysts are called catalytic poisons. With a catalyst, a reaction that is kinetically inhibited by high activation energy can take place in the circumvention of this activation energy.
Heterogeneous catalysts are usually solids, powdered in order to maximize their surface area. Of particular importance in heterogeneous catalysis are the platinum group metals and other transition metals, which are used in hydrogenations, catalytic reforming and in the synthesis of commodity chemicals such as nitric acid and ammonia. Acids are an example of a homogeneous catalyst, they increase the nucleophilicity of carbonyls, allowing a reaction that would not otherwise proceed with electrophiles. The advantage of homogeneous catalysts is the ease of mixing them with the reactants, but they may also be difficult to separate from the products. Therefore, heterogeneous catalysts are preferred in many industrial processes.
In organic chemistry, in addition to oxidation, reduction or acid-base reactions, a number of other reactions can take place which involves covalent bonds between carbon atoms or carbon and heteroatoms (such as oxygen, nitrogen, halogens, etc.). Many specific reactions in organic chemistry are name reactions designated after their discoverers.
In a substitution reaction, a functional group in a particular chemical compound is replaced by another group. These reactions can be distinguished by the type of substituting species into a nucleophilic, electrophilic or radical substitution.
In the first type, a nucleophile, an atom or molecule with an excess of electrons and thus a negative charge or partial charge, replaces another atom or part of the "substrate" molecule. The electron pair from the nucleophile attacks the substrate forming a new bond, while the leaving group departs with an electron pair. The nucleophile may be electrically neutral or negatively charged, whereas the substrate is typically neutral or positively charged. Examples of nucleophiles are hydroxide ion, alkoxides, amines and halides. This type of reaction is found mainly in aliphatic hydrocarbons, and rarely in aromatic hydrocarbon. The latter have high electron density and enter nucleophilic aromatic substitution only with very strong electron withdrawing groups. Nucleophilic substitution can take place by two different mechanisms, SN1 and SN2. In their names, S stands for substitution, N for nucleophilic, and the number represents the kinetic order of the reaction, unimolecular or bimolecular.
The SN1 reaction proceeds in two steps. First, the leaving group is eliminated creating a carbocation. This is followed by a rapid reaction with the nucleophile.
In the SN2 mechanisms, the nucleophile forms a transition state with the attacked molecule, and only then the leaving group is cleaved. These two mechanisms differ in the stereochemistry of the products. SN1 leads to the non-stereospecific addition and does not result in a chiral center, but rather in a set of geometric isomers (cis/trans). In contrast, a reversal (Walden inversion) of the previously existing stereochemistry is observed in the SN2 mechanism.
Electrophilic substitution is the counterpart of the nucleophilic substitution in that the attacking atom or molecule, an electrophile, has low electron density and thus a positive charge. Typical electrophiles are the carbon atom of carbonyl groups, carbocations or sulfur or nitronium cations. This reaction takes place almost exclusively in aromatic hydrocarbons, where it is called electrophilic aromatic substitution. The electrophile attack results in the so-called σ-complex, a transition state in which the aromatic system is abolished. Then, the leaving group, usually a proton, is split off and the aromaticity is restored. An alternative to aromatic substitution is electrophilic aliphatic substitution. It is similar to the nucleophilic aliphatic substitution and also has two major types, SE1 and SE2
In the third type of substitution reaction, radical substitution, the attacking particle is a radical. This process usually takes the form of a chain reaction, for example in the reaction of alkanes with halogens. In the first step, light or heat disintegrates the halogen-containing molecules producing radicals. Then the reaction proceeds as an avalanche until two radicals meet and recombine.
The addition and its counterpart, the elimination, are reactions that change the number of substituents on the carbon atom, and form or cleave multiple bonds. Double and triple bonds can be produced by eliminating a suitable leaving group. Similar to the nucleophilic substitution, there are several possible reaction mechanisms that are named after the respective reaction order. In the E1 mechanism, the leaving group is ejected first, forming a carbocation. The next step, the formation of the double bond, takes place with the elimination of a proton (deprotonation). The leaving order is reversed in the E1cb mechanism, that is the proton is split off first. This mechanism requires the participation of a base. Because of the similar conditions, both reactions in the E1 or E1cb elimination always compete with the SN1 substitution.
The E2 mechanism also requires a base, but there the attack of the base and the elimination of the leaving group proceed simultaneously and produce no ionic intermediate. In contrast to the E1 eliminations, different stereochemical configurations are possible for the reaction product in the E2 mechanism, because the attack of the base preferentially occurs in the anti-position with respect to the leaving group. Because of the similar conditions and reagents, the E2 elimination is always in competition with the SN2-substitution.
The counterpart of elimination is an addition where double or triple bonds are converted into single bonds. Similar to substitution reactions, there are several types of additions distinguished by the type of the attacking particle. For example, in the electrophilic addition of hydrogen bromide, an electrophile (proton) attacks the double bond forming a carbocation, which then reacts with the nucleophile (bromine). The carbocation can be formed on either side of the double bond depending on the groups attached to its ends, and the preferred configuration can be predicted with the Markovnikov's rule. This rule states that "In the heterolytic addition of a polar molecule to an alkene or alkyne, the more electronegative (nucleophilic) atom (or part) of the polar molecule becomes attached to the carbon atom bearing the smaller number of hydrogen atoms."
If the addition of a functional group takes place at the less substituted carbon atom of the double bond, then the electrophilic substitution with acids is not possible. In this case, one has to use the hydroboration–oxidation reaction, wherein the first step, the boron atom acts as electrophile and adds to the less substituted carbon atom. In the second step, the nucleophilic hydroperoxide or halogen anion attacks the boron atom.
While the addition to the electron-rich alkenes and alkynes is mainly electrophilic, the nucleophilic addition plays an important role in the carbon-heteroatom multiple bonds, and especially its most important representative, the carbonyl group. This process is often associated with elimination so that after the reaction the carbonyl group is present again. It is, therefore, called an addition-elimination reaction and may occur in carboxylic acid derivatives such as chlorides, esters or anhydrides. This reaction is often catalyzed by acids or bases, where the acids increase the electrophilicity of the carbonyl group by binding to the oxygen atom, whereas the bases enhance the nucleophilicity of the attacking nucleophile.
Nucleophilic addition of a carbanion or another nucleophile to the double bond of an alpha, beta-unsaturated carbonyl compound can proceed via the Michael reaction, which belongs to the larger class of conjugate additions. This is one of the most useful methods for the mild formation of C–C bonds.
Some additions which can not be executed with nucleophiles and electrophiles can be succeeded with free radicals. As with the free-radical substitution, the radical addition proceeds as a chain reaction, and such reactions are the basis of the free-radical polymerization.
In a rearrangement reaction, the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. These include hydride shift reactions such as the Wagner-Meerwein rearrangement, where a hydrogen, alkyl or aryl group migrates from one carbon to a neighboring carbon. Most rearrangements are associated with the breaking and formation of new carbon-carbon bonds. Other examples are sigmatropic reaction such as the Cope rearrangement.
Cyclic rearrangements include cycloadditions and, more generally, pericyclic reactions, wherein two or more double bond-containing molecules form a cyclic molecule. An important example of cycloaddition reaction is the Diels–Alder reaction (the so-called [4+2] cycloaddition) between a conjugated diene and a substituted alkene to form a substituted cyclohexene system.
Whether a certain cycloaddition would proceed depends on the electronic orbitals of the participating species, as only orbitals with the same sign of wave function will overlap and interact constructively to form new bonds. Cycloaddition is usually assisted by light or heat. These perturbations result in a different arrangement of electrons in the excited state of the involved molecules and therefore in different effects. For example, the [4+2] Diels-Alder reactions can be assisted by heat whereas the [2+2] cycloaddition is selectively induced by light. Because of the orbital character, the potential for developing stereoisomeric products upon cycloaddition is limited, as described by the Woodward–Hoffmann rules.
Biochemical reactions are mainly controlled by enzymes. These proteins can specifically catalyze a single reaction so that reactions can be controlled very precisely. The reaction takes place in the active site, a small part of the enzyme which is usually found in a cleft or pocket lined by amino acid residues, and the rest of the enzyme is used mainly for stabilization. The catalytic action of enzymes relies on several mechanisms including the molecular shape ("induced fit"), bond strain, proximity and orientation of molecules relative to the enzyme, proton donation or withdrawal (acid/base catalysis), electrostatic interactions and many others.
The biochemical reactions that occur in living organisms are collectively known as metabolism. Among the most important of its mechanisms is the anabolism, in which different DNA and enzyme-controlled processes result in the production of large molecules such as proteins and carbohydrates from smaller units. Bioenergetics studies the sources of energy for such reactions. Important energy sources are glucose and oxygen, which can be produced by plants via photosynthesis or assimilated from food and air, respectively. All organisms use this energy to produce adenosine triphosphate (ATP), which can then be used to energize other reactions.
Chemical reactions are central to chemical engineering, where they are used for the synthesis of new compounds from natural raw materials such as petroleum, mineral ores, and oxygen in air. It is essential to make the reaction as efficient as possible, maximizing the yield and minimizing the number of reagents, energy inputs and waste. Catalysts are especially helpful for reducing the energy required for the reaction and increasing its reaction rate.
Some specific reactions have their niche applications. For example, the thermite reaction is used to generate light and heat in pyrotechnics and welding. Although it is less controllable than the more conventional oxy-fuel welding, arc welding and flash welding, it requires much less equipment and is still used to mend rails, especially in remote areas.
Mechanisms of monitoring chemical reactions depend strongly on the reaction rate. Relatively slow processes can be analyzed in situ for the concentrations and identities of the individual ingredients. Important tools of real-time analysis are the measurement of pH and analysis of optical absorption (color) and emission spectra. A less accessible but rather efficient method is the introduction of a radioactive isotope into the reaction and monitoring how it changes over time and where it moves to; this method is often used to analyze the redistribution of substances in the human body. Faster reactions are usually studied with ultrafast laser spectroscopy where utilization of femtosecond lasers allows short-lived transition states to be monitored at a time scaled down to a few femtoseconds. | [
{
"paragraph_id": 0,
"text": "A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The substance (or substances) initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise course of action is part of the reaction mechanism. Chemical reactions are described with chemical equations, which symbolically present the starting materials, end products, and sometimes intermediate products and reaction conditions.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Chemical reactions happen at a characteristic reaction rate at a given temperature and chemical concentration. Typically, reaction rates increase with increasing temperature because there is more thermal energy available to reach the activation energy necessary for breaking bonds between atoms.",
"title": ""
},
{
"paragraph_id": 3,
"text": "A reaction may be classified as redox in which oxidation and reduction occur or non-redox in which there is no oxidation and reduction occurring. Most simple redox reactions may be classified as a combination, decomposition, or single displacement reaction.",
"title": ""
},
{
"paragraph_id": 4,
"text": "Different chemical reactions are used during chemical synthesis in order to obtain the desired product. In biochemistry, a consecutive series of chemical reactions (where the product of one reaction is the reactant of the next reaction) form metabolic pathways. These reactions are often catalyzed by protein enzymes. Enzymes increase the rates of biochemical reactions, so that metabolic syntheses and decompositions impossible under ordinary conditions can occur at the temperature and concentrations present within a cell.",
"title": ""
},
{
"paragraph_id": 5,
"text": "The general concept of a chemical reaction has been extended to reactions between entities smaller than atoms, including nuclear reactions, radioactive decays and reactions between elementary particles, as described by quantum field theory.",
"title": ""
},
{
"paragraph_id": 6,
"text": "Chemical reactions such as combustion in fire, fermentation and the reduction of ores to metals were known since antiquity. Initial theories of transformation of materials were developed by Greek philosophers, such as the Four-Element Theory of Empedocles stating that any substance is composed of the four basic elements – fire, water, air and earth. In the Middle Ages, chemical transformations were studied by alchemists. They attempted, in particular, to convert lead into gold, for which purpose they used reactions of lead and lead-copper alloys with sulfur.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "The artificial production of chemical substances already was a central goal for medieval alchemists. Examples include the synthesis of ammonium chloride from organic substances as described in the works (c. 850–950) attributed to Jābir ibn Ḥayyān, or the production of mineral acids such as sulfuric and nitric acids by later alchemists, starting from c. 1300. The production of mineral acids involved the heating of sulfate and nitrate minerals such as copper sulfate, alum and saltpeter. In the 17th century, Johann Rudolph Glauber produced hydrochloric acid and sodium sulfate by reacting sulfuric acid and sodium chloride. With the development of the lead chamber process in 1746 and the Leblanc process, allowing large-scale production of sulfuric acid and sodium carbonate, respectively, chemical reactions became implemented into the industry. Further optimization of sulfuric acid technology resulted in the contact process in the 1880s, and the Haber process was developed in 1909–1910 for ammonia synthesis.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "From the 16th century, researchers including Jan Baptist van Helmont, Robert Boyle, and Isaac Newton tried to establish theories of experimentally observed chemical transformations. The phlogiston theory was proposed in 1667 by Johann Joachim Becher. It postulated the existence of a fire-like element called \"phlogiston\", which was contained within combustible bodies and released during combustion. This proved to be false in 1785 by Antoine Lavoisier who found the correct explanation of the combustion as a reaction with oxygen from the air.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "Joseph Louis Gay-Lussac recognized in 1808 that gases always react in a certain relationship with each other. Based on this idea and the atomic theory of John Dalton, Joseph Proust had developed the law of definite proportions, which later resulted in the concepts of stoichiometry and chemical equations.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "Regarding the organic chemistry, it was long believed that compounds obtained from living organisms were too complex to be obtained synthetically. According to the concept of vitalism, organic matter was endowed with a \"vital force\" and distinguished from inorganic materials. This separation was ended however by the synthesis of urea from inorganic precursors by Friedrich Wöhler in 1828. Other chemists who brought major contributions to organic chemistry include Alexander William Williamson with his synthesis of ethers and Christopher Kelk Ingold, who, among many discoveries, established the mechanisms of substitution reactions.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "The general characteristics of chemical reactions are:",
"title": "Characteristics"
},
{
"paragraph_id": 12,
"text": "Chemical equations are used to graphically illustrate chemical reactions. They consist of chemical or structural formulas of the reactants on the left and those of the products on the right. They are separated by an arrow (→) which indicates the direction and type of the reaction; the arrow is read as the word \"yields\". The tip of the arrow points in the direction in which the reaction proceeds. A double arrow (⇌) pointing in opposite directions is used for equilibrium reactions. Equations should be balanced according to the stoichiometry, the number of atoms of each species should be the same on both sides of the equation. This is achieved by scaling the number of involved molecules (A, B, C and D in a schematic example below) by the appropriate integers a, b, c and d.",
"title": "Equations"
},
{
"paragraph_id": 13,
"text": "More elaborate reactions are represented by reaction schemes, which in addition to starting materials and products show important intermediates or transition states. Also, some relatively minor additions to the reaction can be indicated above the reaction arrow; examples of such additions are water, heat, illumination, a catalyst, etc. Similarly, some minor products can be placed below the arrow, often with a minus sign.",
"title": "Equations"
},
{
"paragraph_id": 14,
"text": "Retrosynthetic analysis can be applied to design a complex synthesis reaction. Here the analysis starts from the products, for example by splitting selected chemical bonds, to arrive at plausible initial reagents. A special arrow (⇒) is used in retro reactions.",
"title": "Equations"
},
{
"paragraph_id": 15,
"text": "The elementary reaction is the smallest division into which a chemical reaction can be decomposed, it has no intermediate products. Most experimentally observed reactions are built up from many elementary reactions that occur in parallel or sequentially. The actual sequence of the individual elementary reactions is known as reaction mechanism. An elementary reaction involves a few molecules, usually one or two, because of the low probability for several molecules to meet at a certain time.",
"title": "Elementary reactions"
},
{
"paragraph_id": 16,
"text": "The most important elementary reactions are unimolecular and bimolecular reactions. Only one molecule is involved in a unimolecular reaction; it is transformed by isomerization or a dissociation into one or more other molecules. Such reactions require the addition of energy in the form of heat or light. A typical example of a unimolecular reaction is the cis–trans isomerization, in which the cis-form of a compound converts to the trans-form or vice versa.",
"title": "Elementary reactions"
},
{
"paragraph_id": 17,
"text": "In a typical dissociation reaction, a bond in a molecule splits (ruptures) resulting in two molecular fragments. The splitting can be homolytic or heterolytic. In the first case, the bond is divided so that each product retains an electron and becomes a neutral radical. In the second case, both electrons of the chemical bond remain with one of the products, resulting in charged ions. Dissociation plays an important role in triggering chain reactions, such as hydrogen–oxygen or polymerization reactions.",
"title": "Elementary reactions"
},
{
"paragraph_id": 18,
"text": "For bimolecular reactions, two molecules collide and react with each other. Their merger is called chemical synthesis or an addition reaction.",
"title": "Elementary reactions"
},
{
"paragraph_id": 19,
"text": "Another possibility is that only a portion of one molecule is transferred to the other molecule. This type of reaction occurs, for example, in redox and acid-base reactions. In redox reactions, the transferred particle is an electron, whereas in acid-base reactions it is a proton. This type of reaction is also called metathesis.",
"title": "Elementary reactions"
},
{
"paragraph_id": 20,
"text": "for example",
"title": "Elementary reactions"
},
{
"paragraph_id": 21,
"text": "Most chemical reactions are reversible; that is, they can and do run in both directions. The forward and reverse reactions are competing with each other and differ in reaction rates. These rates depend on the concentration and therefore change with the time of the reaction: the reverse rate gradually increases and becomes equal to the rate of the forward reaction, establishing the so-called chemical equilibrium. The time to reach equilibrium depends on parameters such as temperature, pressure, and the materials involved, and is determined by the minimum free energy. In equilibrium, the Gibbs free energy must be zero. The pressure dependence can be explained with the Le Chatelier's principle. For example, an increase in pressure due to decreasing volume causes the reaction to shift to the side with fewer moles of gas.",
"title": "Chemical equilibrium"
},
{
"paragraph_id": 22,
"text": "The reaction yield stabilizes at equilibrium but can be increased by removing the product from the reaction mixture or changed by increasing the temperature or pressure. A change in the concentrations of the reactants does not affect the equilibrium constant but does affect the equilibrium position.",
"title": "Chemical equilibrium"
},
{
"paragraph_id": 23,
"text": "Chemical reactions are determined by the laws of thermodynamics. Reactions can proceed by themselves if they are exergonic, that is if they release free energy. The associated free energy change of the reaction is composed of the changes of two different thermodynamic quantities, enthalpy and entropy:",
"title": "Thermodynamics"
},
{
"paragraph_id": 24,
"text": "Reactions can be exothermic, where ΔH is negative and energy is released. Typical examples of exothermic reactions are combustion, precipitation and crystallization, in which ordered solids are formed from disordered gaseous or liquid phases. In contrast, in endothermic reactions, heat is consumed from the environment. This can occur by increasing the entropy of the system, often through the formation of gaseous or dissolved reaction products, which have higher entropy. Since the entropy term in the free-energy change increases with temperature, many endothermic reactions preferably take place at high temperatures. On the contrary, many exothermic reactions such as crystallization occur preferably at lower temperatures. A change in temperature can sometimes reverse the sign of the enthalpy of a reaction, as for the carbon monoxide reduction of molybdenum dioxide:",
"title": "Thermodynamics"
},
{
"paragraph_id": 25,
"text": "This reaction to form carbon dioxide and molybdenum is endothermic at low temperatures, becoming less so with increasing temperature. ΔH° is zero at 1855 K, and the reaction becomes exothermic above that temperature.",
"title": "Thermodynamics"
},
{
"paragraph_id": 26,
"text": "Changes in temperature can also reverse the direction tendency of a reaction. For example, the water gas shift reaction",
"title": "Thermodynamics"
},
{
"paragraph_id": 27,
"text": "is favored by low temperatures, but its reverse is favored by high temperatures. The shift in reaction direction tendency occurs at 1100 K.",
"title": "Thermodynamics"
},
{
"paragraph_id": 28,
"text": "Reactions can also be characterized by their internal energy change, which takes into account changes in the entropy, volume and chemical potentials. The latter depends, among other things, on the activities of the involved substances.",
"title": "Thermodynamics"
},
{
"paragraph_id": 29,
"text": "The speed at which reactions take place is studied by reaction kinetics. The rate depends on various parameters, such as:",
"title": "Kinetics"
},
{
"paragraph_id": 30,
"text": "Several theories allow calculating the reaction rates at the molecular level. This field is referred to as reaction dynamics. The rate v of a first-order reaction, which could be the disintegration of a substance A, is given by:",
"title": "Kinetics"
},
{
"paragraph_id": 31,
"text": "Its integration yields:",
"title": "Kinetics"
},
{
"paragraph_id": 32,
"text": "Here k is the first-order rate constant, having dimension 1/time, [A](t) is the concentration at a time t and [A]0 is the initial concentration. The rate of a first-order reaction depends only on the concentration and the properties of the involved substance, and the reaction itself can be described with a characteristic half-life. More than one time constant is needed when describing reactions of higher order. The temperature dependence of the rate constant usually follows the Arrhenius equation:",
"title": "Kinetics"
},
{
"paragraph_id": 33,
"text": "where Ea is the activation energy and kB is the Boltzmann constant. One of the simplest models of reaction rate is the collision theory. More realistic models are tailored to a specific problem and include the transition state theory, the calculation of the potential energy surface, the Marcus theory and the Rice–Ramsperger–Kassel–Marcus (RRKM) theory.",
"title": "Kinetics"
},
{
"paragraph_id": 34,
"text": "In a synthesis reaction, two or more simple substances combine to form a more complex substance. These reactions are in the general form:",
"title": "Reaction types"
},
{
"paragraph_id": 35,
"text": "Two or more reactants yielding one product is another way to identify a synthesis reaction. One example of a synthesis reaction is the combination of iron and sulfur to form iron(II) sulfide:",
"title": "Reaction types"
},
{
"paragraph_id": 36,
"text": "Another example is simple hydrogen gas combined with simple oxygen gas to produce a more complex substance, such as water.",
"title": "Reaction types"
},
{
"paragraph_id": 37,
"text": "A decomposition reaction is when a more complex substance breaks down into its more simple parts. It is thus the opposite of a synthesis reaction and can be written as",
"title": "Reaction types"
},
{
"paragraph_id": 38,
"text": "One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas:",
"title": "Reaction types"
},
{
"paragraph_id": 39,
"text": "In a single displacement reaction, a single uncombined element replaces another in a compound; in other words, one element trades places with another element in a compound These reactions come in the general form of:",
"title": "Reaction types"
},
{
"paragraph_id": 40,
"text": "One example of a single displacement reaction is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas:",
"title": "Reaction types"
},
{
"paragraph_id": 41,
"text": "In a double displacement reaction, the anions and cations of two compounds switch places and form two entirely different compounds. These reactions are in the general form:",
"title": "Reaction types"
},
{
"paragraph_id": 42,
"text": "For example, when barium chloride (BaCl2) and magnesium sulfate (MgSO4) react, the SO4 anion switches places with the 2Cl anion, giving the compounds BaSO4 and MgCl2.",
"title": "Reaction types"
},
{
"paragraph_id": 43,
"text": "Another example of a double displacement reaction is the reaction of lead(II) nitrate with potassium iodide to form lead(II) iodide and potassium nitrate:",
"title": "Reaction types"
},
{
"paragraph_id": 44,
"text": "According to Le Châtelier's Principle, reactions may proceed in the forward or reverse direction until they end or reach equilibrium.",
"title": "Reaction types"
},
{
"paragraph_id": 45,
"text": "Reactions that proceed in the forward direction to approach equilibrium are often called spontaneous reactions, that is, Δ G {\\displaystyle \\Delta G} is negative, which means that if they occur at constant temperature and pressure, they decrease the Gibbs free energy of the reaction. They don't require much energy to proceed in the forward direction. Most reactions are forward reactions. Examples:",
"title": "Reaction types"
},
{
"paragraph_id": 46,
"text": "Reactions that proceed in the backward direction to approach equilibrium are often called non-spontaneous reactions, that is, Δ G {\\displaystyle \\Delta G} is positive, which means that if they occur at constant temperature and pressure, they increase the Gibbs free energy of the reaction. They require input of energy to proceed in the forward direction. Examples include:",
"title": "Reaction types"
},
{
"paragraph_id": 47,
"text": "In a combustion reaction, an element or compound reacts with an oxidant, usually oxygen, often producing energy in the form of heat or light. Combustion reactions frequently involve a hydrocarbon. For instance, the combustion of 1 mole (114 g) of octane in oxygen",
"title": "Reaction types"
},
{
"paragraph_id": 48,
"text": "releases 5500 kJ. A combustion reaction can also result from carbon, magnesium or sulfur reacting with oxygen.",
"title": "Reaction types"
},
{
"paragraph_id": 49,
"text": "Redox reactions can be understood in terms of the transfer of electrons from one involved species (reducing agent) to another (oxidizing agent). In this process, the former species is oxidized and the latter is reduced. Though sufficient for many purposes, these descriptions are not precisely correct. Oxidation is better defined as an increase in oxidation state of atoms and reduction as a decrease in oxidation state. In practice, the transfer of electrons will always change the oxidation state, but there are many reactions that are classed as \"redox\" even though no electron transfer occurs (such as those involving covalent bonds).",
"title": "Reaction types"
},
{
"paragraph_id": 50,
"text": "In the following redox reaction, hazardous sodium metal reacts with toxic chlorine gas to form the ionic compound sodium chloride, or common table salt:",
"title": "Reaction types"
},
{
"paragraph_id": 51,
"text": "In the reaction, sodium metal goes from an oxidation state of 0 (as it is a pure element) to +1: in other words, the sodium lost one electron and is said to have been oxidized. On the other hand, the chlorine gas goes from an oxidation of 0 (it is also a pure element) to −1: the chlorine gains one electron and is said to have been reduced. Because the chlorine is the one reduced, it is considered the electron acceptor, or in other words, induces oxidation in the sodium – thus the chlorine gas is considered the oxidizing agent. Conversely, the sodium is oxidized or is the electron donor, and thus induces a reduction in the other species and is considered the reducing agent.",
"title": "Reaction types"
},
{
"paragraph_id": 52,
"text": "Which of the involved reactants would be a reducing or oxidizing agent can be predicted from the electronegativity of their elements. Elements with low electronegativities, such as most metals, easily donate electrons and oxidize – they are reducing agents. On the contrary, many oxides or ions with high oxidation numbers of their non-oxygen atoms, such as H2O2, MnO4, CrO3, Cr2O7, or OsO4, can gain one or two extra electrons and are strong oxidizing agents.",
"title": "Reaction types"
},
{
"paragraph_id": 53,
"text": "For some main-group elements the number of electrons donated or accepted in a redox reaction can be predicted from the electron configuration of the reactant element. Elements try to reach the low-energy noble gas configuration, and therefore alkali metals and halogens will donate and accept one electron, respectively. Noble gases themselves are chemically inactive.",
"title": "Reaction types"
},
{
"paragraph_id": 54,
"text": "The overall redox reaction can be balanced by combining the oxidation and reduction half-reactions multiplied by coefficients such that the number of electrons lost in the oxidation equals the number of electrons gained in the reduction.",
"title": "Reaction types"
},
{
"paragraph_id": 55,
"text": "An important class of redox reactions are the electrolytic electrochemical reactions, where electrons from the power supply at the negative electrode are used as the reducing agent and electron withdrawal at the positive electrode as the oxidizing agent. These reactions are particularly important for the production of chemical elements, such as chlorine or aluminium. The reverse process, in which electrons are released in redox reactions and chemical energy is converted to electrical energy, is possible and used in batteries.",
"title": "Reaction types"
},
{
"paragraph_id": 56,
"text": "In complexation reactions, several ligands react with a metal atom to form a coordination complex. This is achieved by providing lone pairs of the ligand into empty orbitals of the metal atom and forming dipolar bonds. The ligands are Lewis bases, they can be both ions and neutral molecules, such as carbon monoxide, ammonia or water. The number of ligands that react with a central metal atom can be found using the 18-electron rule, saying that the valence shells of a transition metal will collectively accommodate 18 electrons, whereas the symmetry of the resulting complex can be predicted with the crystal field theory and ligand field theory. Complexation reactions also include ligand exchange, in which one or more ligands are replaced by another, and redox processes which change the oxidation state of the central metal atom.",
"title": "Reaction types"
},
{
"paragraph_id": 57,
"text": "In the Brønsted–Lowry acid–base theory, an acid–base reaction involves a transfer of protons (H) from one species (the acid) to another (the base). When a proton is removed from an acid, the resulting species is termed that acid's conjugate base. When the proton is accepted by a base, the resulting species is termed that base's conjugate acid. In other words, acids act as proton donors and bases act as proton acceptors according to the following equation:",
"title": "Reaction types"
},
{
"paragraph_id": 58,
"text": "The reverse reaction is possible, and thus the acid/base and conjugated base/acid are always in equilibrium. The equilibrium is determined by the acid and base dissociation constants (Ka and Kb) of the involved substances. A special case of the acid-base reaction is the neutralization where an acid and a base, taken at the exact same amounts, form a neutral salt.",
"title": "Reaction types"
},
{
"paragraph_id": 59,
"text": "Acid-base reactions can have different definitions depending on the acid-base concept employed. Some of the most common are:",
"title": "Reaction types"
},
{
"paragraph_id": 60,
"text": "Precipitation is the formation of a solid in a solution or inside another solid during a chemical reaction. It usually takes place when the concentration of dissolved ions exceeds the solubility limit and forms an insoluble salt. This process can be assisted by adding a precipitating agent or by the removal of the solvent. Rapid precipitation results in an amorphous or microcrystalline residue and a slow process can yield single crystals. The latter can also be obtained by recrystallization from microcrystalline salts.",
"title": "Reaction types"
},
{
"paragraph_id": 61,
"text": "Reactions can take place between two solids. However, because of the relatively small diffusion rates in solids, the corresponding chemical reactions are very slow in comparison to liquid and gas phase reactions. They are accelerated by increasing the reaction temperature and finely dividing the reactant to increase the contacting surface area.",
"title": "Reaction types"
},
{
"paragraph_id": 62,
"text": "The reaction can take place at the solid|gas interface, surfaces at very low pressure such as ultra-high vacuum. Via scanning tunneling microscopy, it is possible to observe reactions at the solid|gas interface in real space, if the time scale of the reaction is in the correct range. Reactions at the solid|gas interface are in some cases related to catalysis.",
"title": "Reaction types"
},
{
"paragraph_id": 63,
"text": "In photochemical reactions, atoms and molecules absorb energy (photons) of the illumination light and convert it into an excited state. They can then release this energy by breaking chemical bonds, thereby producing radicals. Photochemical reactions include hydrogen–oxygen reactions, radical polymerization, chain reactions and rearrangement reactions.",
"title": "Reaction types"
},
{
"paragraph_id": 64,
"text": "Many important processes involve photochemistry. The premier example is photosynthesis, in which most plants use solar energy to convert carbon dioxide and water into glucose, disposing of oxygen as a side-product. Humans rely on photochemistry for the formation of vitamin D, and vision is initiated by a photochemical reaction of rhodopsin. In fireflies, an enzyme in the abdomen catalyzes a reaction that results in bioluminescence. Many significant photochemical reactions, such as ozone formation, occur in the Earth atmosphere and constitute atmospheric chemistry.",
"title": "Reaction types"
},
{
"paragraph_id": 65,
"text": "In catalysis, the reaction does not proceed directly, but through a reaction with a third substance known as catalyst. Although the catalyst takes part in the reaction, forming weak bonds with reactants or intermediates, it is returned to its original state by the end of the reaction and so is not consumed. However, it can be inhibited, deactivated or destroyed by secondary processes. Catalysts can be used in a different phase (heterogeneous) or in the same phase (homogeneous) as the reactants. In heterogeneous catalysis, typical secondary processes include coking where the catalyst becomes covered by polymeric side products. Additionally, heterogeneous catalysts can dissolve into the solution in a solid-liquid system or evaporate in a solid–gas system. Catalysts can only speed up the reaction – chemicals that slow down the reaction are called inhibitors. Substances that increase the activity of catalysts are called promoters, and substances that deactivate catalysts are called catalytic poisons. With a catalyst, a reaction that is kinetically inhibited by high activation energy can take place in the circumvention of this activation energy.",
"title": "Catalysis"
},
{
"paragraph_id": 66,
"text": "Heterogeneous catalysts are usually solids, powdered in order to maximize their surface area. Of particular importance in heterogeneous catalysis are the platinum group metals and other transition metals, which are used in hydrogenations, catalytic reforming and in the synthesis of commodity chemicals such as nitric acid and ammonia. Acids are an example of a homogeneous catalyst, they increase the nucleophilicity of carbonyls, allowing a reaction that would not otherwise proceed with electrophiles. The advantage of homogeneous catalysts is the ease of mixing them with the reactants, but they may also be difficult to separate from the products. Therefore, heterogeneous catalysts are preferred in many industrial processes.",
"title": "Catalysis"
},
{
"paragraph_id": 67,
"text": "In organic chemistry, in addition to oxidation, reduction or acid-base reactions, a number of other reactions can take place which involves covalent bonds between carbon atoms or carbon and heteroatoms (such as oxygen, nitrogen, halogens, etc.). Many specific reactions in organic chemistry are name reactions designated after their discoverers.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 68,
"text": "In a substitution reaction, a functional group in a particular chemical compound is replaced by another group. These reactions can be distinguished by the type of substituting species into a nucleophilic, electrophilic or radical substitution.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 69,
"text": "In the first type, a nucleophile, an atom or molecule with an excess of electrons and thus a negative charge or partial charge, replaces another atom or part of the \"substrate\" molecule. The electron pair from the nucleophile attacks the substrate forming a new bond, while the leaving group departs with an electron pair. The nucleophile may be electrically neutral or negatively charged, whereas the substrate is typically neutral or positively charged. Examples of nucleophiles are hydroxide ion, alkoxides, amines and halides. This type of reaction is found mainly in aliphatic hydrocarbons, and rarely in aromatic hydrocarbon. The latter have high electron density and enter nucleophilic aromatic substitution only with very strong electron withdrawing groups. Nucleophilic substitution can take place by two different mechanisms, SN1 and SN2. In their names, S stands for substitution, N for nucleophilic, and the number represents the kinetic order of the reaction, unimolecular or bimolecular.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 70,
"text": "The SN1 reaction proceeds in two steps. First, the leaving group is eliminated creating a carbocation. This is followed by a rapid reaction with the nucleophile.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 71,
"text": "In the SN2 mechanisms, the nucleophile forms a transition state with the attacked molecule, and only then the leaving group is cleaved. These two mechanisms differ in the stereochemistry of the products. SN1 leads to the non-stereospecific addition and does not result in a chiral center, but rather in a set of geometric isomers (cis/trans). In contrast, a reversal (Walden inversion) of the previously existing stereochemistry is observed in the SN2 mechanism.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 72,
"text": "Electrophilic substitution is the counterpart of the nucleophilic substitution in that the attacking atom or molecule, an electrophile, has low electron density and thus a positive charge. Typical electrophiles are the carbon atom of carbonyl groups, carbocations or sulfur or nitronium cations. This reaction takes place almost exclusively in aromatic hydrocarbons, where it is called electrophilic aromatic substitution. The electrophile attack results in the so-called σ-complex, a transition state in which the aromatic system is abolished. Then, the leaving group, usually a proton, is split off and the aromaticity is restored. An alternative to aromatic substitution is electrophilic aliphatic substitution. It is similar to the nucleophilic aliphatic substitution and also has two major types, SE1 and SE2",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 73,
"text": "In the third type of substitution reaction, radical substitution, the attacking particle is a radical. This process usually takes the form of a chain reaction, for example in the reaction of alkanes with halogens. In the first step, light or heat disintegrates the halogen-containing molecules producing radicals. Then the reaction proceeds as an avalanche until two radicals meet and recombine.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 74,
"text": "The addition and its counterpart, the elimination, are reactions that change the number of substituents on the carbon atom, and form or cleave multiple bonds. Double and triple bonds can be produced by eliminating a suitable leaving group. Similar to the nucleophilic substitution, there are several possible reaction mechanisms that are named after the respective reaction order. In the E1 mechanism, the leaving group is ejected first, forming a carbocation. The next step, the formation of the double bond, takes place with the elimination of a proton (deprotonation). The leaving order is reversed in the E1cb mechanism, that is the proton is split off first. This mechanism requires the participation of a base. Because of the similar conditions, both reactions in the E1 or E1cb elimination always compete with the SN1 substitution.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 75,
"text": "The E2 mechanism also requires a base, but there the attack of the base and the elimination of the leaving group proceed simultaneously and produce no ionic intermediate. In contrast to the E1 eliminations, different stereochemical configurations are possible for the reaction product in the E2 mechanism, because the attack of the base preferentially occurs in the anti-position with respect to the leaving group. Because of the similar conditions and reagents, the E2 elimination is always in competition with the SN2-substitution.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 76,
"text": "The counterpart of elimination is an addition where double or triple bonds are converted into single bonds. Similar to substitution reactions, there are several types of additions distinguished by the type of the attacking particle. For example, in the electrophilic addition of hydrogen bromide, an electrophile (proton) attacks the double bond forming a carbocation, which then reacts with the nucleophile (bromine). The carbocation can be formed on either side of the double bond depending on the groups attached to its ends, and the preferred configuration can be predicted with the Markovnikov's rule. This rule states that \"In the heterolytic addition of a polar molecule to an alkene or alkyne, the more electronegative (nucleophilic) atom (or part) of the polar molecule becomes attached to the carbon atom bearing the smaller number of hydrogen atoms.\"",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 77,
"text": "If the addition of a functional group takes place at the less substituted carbon atom of the double bond, then the electrophilic substitution with acids is not possible. In this case, one has to use the hydroboration–oxidation reaction, wherein the first step, the boron atom acts as electrophile and adds to the less substituted carbon atom. In the second step, the nucleophilic hydroperoxide or halogen anion attacks the boron atom.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 78,
"text": "While the addition to the electron-rich alkenes and alkynes is mainly electrophilic, the nucleophilic addition plays an important role in the carbon-heteroatom multiple bonds, and especially its most important representative, the carbonyl group. This process is often associated with elimination so that after the reaction the carbonyl group is present again. It is, therefore, called an addition-elimination reaction and may occur in carboxylic acid derivatives such as chlorides, esters or anhydrides. This reaction is often catalyzed by acids or bases, where the acids increase the electrophilicity of the carbonyl group by binding to the oxygen atom, whereas the bases enhance the nucleophilicity of the attacking nucleophile.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 79,
"text": "Nucleophilic addition of a carbanion or another nucleophile to the double bond of an alpha, beta-unsaturated carbonyl compound can proceed via the Michael reaction, which belongs to the larger class of conjugate additions. This is one of the most useful methods for the mild formation of C–C bonds.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 80,
"text": "Some additions which can not be executed with nucleophiles and electrophiles can be succeeded with free radicals. As with the free-radical substitution, the radical addition proceeds as a chain reaction, and such reactions are the basis of the free-radical polymerization.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 81,
"text": "In a rearrangement reaction, the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. These include hydride shift reactions such as the Wagner-Meerwein rearrangement, where a hydrogen, alkyl or aryl group migrates from one carbon to a neighboring carbon. Most rearrangements are associated with the breaking and formation of new carbon-carbon bonds. Other examples are sigmatropic reaction such as the Cope rearrangement.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 82,
"text": "Cyclic rearrangements include cycloadditions and, more generally, pericyclic reactions, wherein two or more double bond-containing molecules form a cyclic molecule. An important example of cycloaddition reaction is the Diels–Alder reaction (the so-called [4+2] cycloaddition) between a conjugated diene and a substituted alkene to form a substituted cyclohexene system.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 83,
"text": "Whether a certain cycloaddition would proceed depends on the electronic orbitals of the participating species, as only orbitals with the same sign of wave function will overlap and interact constructively to form new bonds. Cycloaddition is usually assisted by light or heat. These perturbations result in a different arrangement of electrons in the excited state of the involved molecules and therefore in different effects. For example, the [4+2] Diels-Alder reactions can be assisted by heat whereas the [2+2] cycloaddition is selectively induced by light. Because of the orbital character, the potential for developing stereoisomeric products upon cycloaddition is limited, as described by the Woodward–Hoffmann rules.",
"title": "Reactions in organic chemistry"
},
{
"paragraph_id": 84,
"text": "Biochemical reactions are mainly controlled by enzymes. These proteins can specifically catalyze a single reaction so that reactions can be controlled very precisely. The reaction takes place in the active site, a small part of the enzyme which is usually found in a cleft or pocket lined by amino acid residues, and the rest of the enzyme is used mainly for stabilization. The catalytic action of enzymes relies on several mechanisms including the molecular shape (\"induced fit\"), bond strain, proximity and orientation of molecules relative to the enzyme, proton donation or withdrawal (acid/base catalysis), electrostatic interactions and many others.",
"title": "Biochemical reactions"
},
{
"paragraph_id": 85,
"text": "The biochemical reactions that occur in living organisms are collectively known as metabolism. Among the most important of its mechanisms is the anabolism, in which different DNA and enzyme-controlled processes result in the production of large molecules such as proteins and carbohydrates from smaller units. Bioenergetics studies the sources of energy for such reactions. Important energy sources are glucose and oxygen, which can be produced by plants via photosynthesis or assimilated from food and air, respectively. All organisms use this energy to produce adenosine triphosphate (ATP), which can then be used to energize other reactions.",
"title": "Biochemical reactions"
},
{
"paragraph_id": 86,
"text": "Chemical reactions are central to chemical engineering, where they are used for the synthesis of new compounds from natural raw materials such as petroleum, mineral ores, and oxygen in air. It is essential to make the reaction as efficient as possible, maximizing the yield and minimizing the number of reagents, energy inputs and waste. Catalysts are especially helpful for reducing the energy required for the reaction and increasing its reaction rate.",
"title": "Applications"
},
{
"paragraph_id": 87,
"text": "Some specific reactions have their niche applications. For example, the thermite reaction is used to generate light and heat in pyrotechnics and welding. Although it is less controllable than the more conventional oxy-fuel welding, arc welding and flash welding, it requires much less equipment and is still used to mend rails, especially in remote areas.",
"title": "Applications"
},
{
"paragraph_id": 88,
"text": "Mechanisms of monitoring chemical reactions depend strongly on the reaction rate. Relatively slow processes can be analyzed in situ for the concentrations and identities of the individual ingredients. Important tools of real-time analysis are the measurement of pH and analysis of optical absorption (color) and emission spectra. A less accessible but rather efficient method is the introduction of a radioactive isotope into the reaction and monitoring how it changes over time and where it moves to; this method is often used to analyze the redistribution of substances in the human body. Faster reactions are usually studied with ultrafast laser spectroscopy where utilization of femtosecond lasers allows short-lived transition states to be monitored at a time scaled down to a few femtoseconds.",
"title": "Monitoring"
}
] | A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei, and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur. The substance initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise course of action is part of the reaction mechanism. Chemical reactions are described with chemical equations, which symbolically present the starting materials, end products, and sometimes intermediate products and reaction conditions. Chemical reactions happen at a characteristic reaction rate at a given temperature and chemical concentration. Typically, reaction rates increase with increasing temperature because there is more thermal energy available to reach the activation energy necessary for breaking bonds between atoms. A reaction may be classified as redox in which oxidation and reduction occur or non-redox in which there is no oxidation and reduction occurring. Most simple redox reactions may be classified as a combination, decomposition, or single displacement reaction. Different chemical reactions are used during chemical synthesis in order to obtain the desired product. In biochemistry, a consecutive series of chemical reactions form metabolic pathways. These reactions are often catalyzed by protein enzymes. Enzymes increase the rates of biochemical reactions, so that metabolic syntheses and decompositions impossible under ordinary conditions can occur at the temperature and concentrations present within a cell. The general concept of a chemical reaction has been extended to reactions between entities smaller than atoms, including nuclear reactions, radioactive decays and reactions between elementary particles, as described by quantum field theory. | 2001-11-02T05:33:25Z | 2023-10-08T12:42:05Z | [
"Template:Reflist",
"Template:Underset",
"Template:Portal",
"Template:BranchesofChemistry",
"Template:Footer energy",
"Template:Merge from",
"Template:Mvar",
"Template:Chem",
"Template:Wikiquote",
"Template:Cite journal",
"Template:Cite book",
"Template:JerryMarch",
"Template:Short description",
"Template:Math",
"Template:Val",
"Template:Chemical synthesis",
"Template:More footnotes",
"Template:Cite encyclopedia",
"Template:Organic reactions",
"Template:Cite EB1911",
"Template:Authority control",
"Template:Pp",
"Template:Further",
"Template:Cite web",
"Template:Expand section",
"Template:Main",
"Template:Clear",
"Template:GoldBookRef",
"Template:Webarchive",
"Template:Chem2",
"Template:Eqm",
"Template:Multiple image"
] | https://en.wikipedia.org/wiki/Chemical_reaction |
6,272 | Charleston | Charleston most commonly refers to:
Charleston may also refer to: | [
{
"paragraph_id": 0,
"text": "Charleston most commonly refers to:",
"title": ""
},
{
"paragraph_id": 1,
"text": "Charleston may also refer to:",
"title": ""
}
] | Charleston most commonly refers to: Charleston, South Carolina
Charleston, West Virginia, the state capital
Charleston (dance) Charleston may also refer to: | 2023-06-20T05:44:02Z | [
"Template:Wiktionary",
"Template:TOC right",
"Template:Disambiguation"
] | https://en.wikipedia.org/wiki/Charleston |
|
6,276 | Casiquiare canal | The Casiquiare river (Spanish pronunciation: [kasiˈkjaɾe]) is a distributary of the upper Orinoco flowing southward into the Rio Negro, in Venezuela, South America. As such, it forms a unique natural canal between the Orinoco and Amazon river systems. It is the world's largest river of the kind that links two major river systems, a so-called bifurcation. The area forms a water divide, more dramatically at regional flood stage.
The name Casiquiare, first used in that form by Manuel Román, likely derives from the Ye'kuana language name of the river, Kashishiwadi.
The first to discover and describe it was Cristóbal Diatristán de Acuña in 1639.
In 1744 a Jesuit priest named Manuel Román, while ascending the Orinoco River in the region of La Esmeralda, met some Portuguese slave-traders from the settlements on the Rio Negro. The Portuguese insisted they were not in Spanish territory but on a tributary of the Amazon; they invited Román back with them to prove their claim. He accompanied them on their return, by way of the Casiquiare canal, and afterwards retraced his route to the Orinoco. Along the way, he made first contact with the Ye'kuana people, whom he enlisted to help in his journey. Charles Marie de La Condamine, seven months later, was able to give to the Académie française an account of Father Román's voyage, and thus confirm the existence of this waterway, first reported by Father Acuña in 1639.
Little credence was given to Román's statement until it was verified, in 1756, by the Spanish Boundary-line Commission of José Yturriaga and Solano. In 1800 German scientist Alexander von Humboldt and French botanist Aimé Bonpland explored the river. During a 1924–25 expedition, Alexander H. Rice Jr. of Harvard University traveled up the Orinoco, traversed the Casiquiare canal, and descended the Rio Negro to the Amazon at Manaus. It was the first expedition to use aerial photography and shortwave radio for mapping of the region. In 1968 the Casiquiare was navigated by an SRN6 hovercraft during a National Geographic expedition.
The origin of the Casiquiare, at the River Orinoco, is 14 kilometres (9 mi) below the mission of La Esmeralda at 3°8′18.5″N 65°52′42.5″W / 3.138472°N 65.878472°W / 3.138472; -65.878472, and about 123 metres (404 ft) above sea level. Its mouth at the Rio Negro, an affluent of the Amazon River, is near the town of San Carlos and is 91 metres (299 ft) above sea level.
The general course is south-west, and its length, including windings, is about 320 kilometres (200 mi). Its width, at its bifurcation with the Orinoco, is approximately 90 metres (300 ft), with a current towards the Rio Negro of 0.3 metres per second (0.75 mph). However, as it gains in volume from the very numerous tributary streams, large and small, that it receives en route, its velocity increases, and in the wet season reaches 2.2 metres per second (5 mph), even 3.6 metres per second (8 mph) in certain stretches. It broadens considerably as it approaches its mouth, where it is about 533 metres (1,750 ft) wide. The volume of water the Casiquiare captures from the Orinoco is small in comparison to what it accumulates in its course. Nevertheless, the geological processes are ongoing, and evidence points to a slow and gradual increase in the size of Casiquiare. It is likely that stream capture is in progress, i.e. what currently is the uppermost Orinoco basin, including Cunucunuma River, eventually will be entirely diverted by the Casiquiare into the Amazon basin.
In flood time, it is said to have a second connection with the Rio Negro by a branch, which it throws off to the westward, called the Itinivini, which leaves it at a point about 80 kilometres (50 mi) above its mouth. In the dry season, it has shallows, and is obstructed by sandbanks, a few rapids and granite rocks. Its shores are densely wooded, and the soil more fertile than that along the Rio Negro. The general slope of the plains through which the canal runs is south-west, but those of the Rio Negro slope south-east.
The Casiquiare is not a sluggish canal on a flat tableland, but a great, rapid river which, if its upper waters had not found contact with the Orinoco, perhaps by cutting back, would belong entirely to the Negro branch of the Amazon.
To the west of the Casiquiare, there is a much shorter and easier portage between the Orinoco and Amazon basins, called the isthmus of Pimichin, which is reached by ascending the Temi branch of the Atabapo River, an affluent of the Orinoco. Although the Temi is somewhat obstructed, it is believed that it could easily be made navigable for small craft. The isthmus is 10 miles (16 km) across, with undulating ground, nowhere over 15 metres (50 ft) high, with swamps and marshes. In the early 20th century, it was much used for the transit of large canoes, which were hauled across it from the Temi River and reached the Rio Negro by a little stream called the Pimichin.
The Casiquiare canal – Orinoco River hydrographic divide is a representation of the hydrographic water divide that delineates the separation between the Orinoco Basin and the Amazon Basin. (The Orinoco Basin flows west–north–northeast into the Caribbean; the Amazon Basin flows east into the western Atlantic in the extreme northeast of Brazil.)
Essentially the river divide is a west-flowing, upriver section of Venezuela's Orinoco River with an outflow to the south into the Amazon Basin. This named outflow is the Casiquiare canal, which, as it heads downstream (southerly), picks up speed and also accumulates water volume.
The greatest manifestation of the divide is during floods. During flood stage, the Casiquiare's main outflow point into the Rio Negro is supplemented by an overflow that is a second, and more minor, entry river bifurcation into the Rio Negro and upstream from its major, common low-water entry confluence with the Rio Negro. At flood, the river becomes an area flow source, far more than a narrow confined river.
The Casiquiare canal connects the upper Orinoco, 14 kilometres (9 mi) below the mission of Esmeraldas, with the Rio Negro affluent of the Amazon River near the town of San Carlos.
The simplest description (besides the entire area-floodplain) of the water divide is a "south-bank Orinoco River strip" at the exit point of the Orinoco, also the origin of the Casiquiare canal. However, during the Orinoco's flood stage, that single, simply defined "origin of the canal" is turned into a region, and an entire strip along the southern bank of the Orinoco River. | [
{
"paragraph_id": 0,
"text": "The Casiquiare river (Spanish pronunciation: [kasiˈkjaɾe]) is a distributary of the upper Orinoco flowing southward into the Rio Negro, in Venezuela, South America. As such, it forms a unique natural canal between the Orinoco and Amazon river systems. It is the world's largest river of the kind that links two major river systems, a so-called bifurcation. The area forms a water divide, more dramatically at regional flood stage.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The name Casiquiare, first used in that form by Manuel Román, likely derives from the Ye'kuana language name of the river, Kashishiwadi.",
"title": "Etymology"
},
{
"paragraph_id": 2,
"text": "The first to discover and describe it was Cristóbal Diatristán de Acuña in 1639.",
"title": "Discovery"
},
{
"paragraph_id": 3,
"text": "In 1744 a Jesuit priest named Manuel Román, while ascending the Orinoco River in the region of La Esmeralda, met some Portuguese slave-traders from the settlements on the Rio Negro. The Portuguese insisted they were not in Spanish territory but on a tributary of the Amazon; they invited Román back with them to prove their claim. He accompanied them on their return, by way of the Casiquiare canal, and afterwards retraced his route to the Orinoco. Along the way, he made first contact with the Ye'kuana people, whom he enlisted to help in his journey. Charles Marie de La Condamine, seven months later, was able to give to the Académie française an account of Father Román's voyage, and thus confirm the existence of this waterway, first reported by Father Acuña in 1639.",
"title": "Discovery"
},
{
"paragraph_id": 4,
"text": "Little credence was given to Román's statement until it was verified, in 1756, by the Spanish Boundary-line Commission of José Yturriaga and Solano. In 1800 German scientist Alexander von Humboldt and French botanist Aimé Bonpland explored the river. During a 1924–25 expedition, Alexander H. Rice Jr. of Harvard University traveled up the Orinoco, traversed the Casiquiare canal, and descended the Rio Negro to the Amazon at Manaus. It was the first expedition to use aerial photography and shortwave radio for mapping of the region. In 1968 the Casiquiare was navigated by an SRN6 hovercraft during a National Geographic expedition.",
"title": "Discovery"
},
{
"paragraph_id": 5,
"text": "The origin of the Casiquiare, at the River Orinoco, is 14 kilometres (9 mi) below the mission of La Esmeralda at 3°8′18.5″N 65°52′42.5″W / 3.138472°N 65.878472°W / 3.138472; -65.878472, and about 123 metres (404 ft) above sea level. Its mouth at the Rio Negro, an affluent of the Amazon River, is near the town of San Carlos and is 91 metres (299 ft) above sea level.",
"title": "Geography"
},
{
"paragraph_id": 6,
"text": "The general course is south-west, and its length, including windings, is about 320 kilometres (200 mi). Its width, at its bifurcation with the Orinoco, is approximately 90 metres (300 ft), with a current towards the Rio Negro of 0.3 metres per second (0.75 mph). However, as it gains in volume from the very numerous tributary streams, large and small, that it receives en route, its velocity increases, and in the wet season reaches 2.2 metres per second (5 mph), even 3.6 metres per second (8 mph) in certain stretches. It broadens considerably as it approaches its mouth, where it is about 533 metres (1,750 ft) wide. The volume of water the Casiquiare captures from the Orinoco is small in comparison to what it accumulates in its course. Nevertheless, the geological processes are ongoing, and evidence points to a slow and gradual increase in the size of Casiquiare. It is likely that stream capture is in progress, i.e. what currently is the uppermost Orinoco basin, including Cunucunuma River, eventually will be entirely diverted by the Casiquiare into the Amazon basin.",
"title": "Geography"
},
{
"paragraph_id": 7,
"text": "In flood time, it is said to have a second connection with the Rio Negro by a branch, which it throws off to the westward, called the Itinivini, which leaves it at a point about 80 kilometres (50 mi) above its mouth. In the dry season, it has shallows, and is obstructed by sandbanks, a few rapids and granite rocks. Its shores are densely wooded, and the soil more fertile than that along the Rio Negro. The general slope of the plains through which the canal runs is south-west, but those of the Rio Negro slope south-east.",
"title": "Geography"
},
{
"paragraph_id": 8,
"text": "The Casiquiare is not a sluggish canal on a flat tableland, but a great, rapid river which, if its upper waters had not found contact with the Orinoco, perhaps by cutting back, would belong entirely to the Negro branch of the Amazon.",
"title": "Geography"
},
{
"paragraph_id": 9,
"text": "To the west of the Casiquiare, there is a much shorter and easier portage between the Orinoco and Amazon basins, called the isthmus of Pimichin, which is reached by ascending the Temi branch of the Atabapo River, an affluent of the Orinoco. Although the Temi is somewhat obstructed, it is believed that it could easily be made navigable for small craft. The isthmus is 10 miles (16 km) across, with undulating ground, nowhere over 15 metres (50 ft) high, with swamps and marshes. In the early 20th century, it was much used for the transit of large canoes, which were hauled across it from the Temi River and reached the Rio Negro by a little stream called the Pimichin.",
"title": "Geography"
},
{
"paragraph_id": 10,
"text": "The Casiquiare canal – Orinoco River hydrographic divide is a representation of the hydrographic water divide that delineates the separation between the Orinoco Basin and the Amazon Basin. (The Orinoco Basin flows west–north–northeast into the Caribbean; the Amazon Basin flows east into the western Atlantic in the extreme northeast of Brazil.)",
"title": "Hydrographic divide"
},
{
"paragraph_id": 11,
"text": "Essentially the river divide is a west-flowing, upriver section of Venezuela's Orinoco River with an outflow to the south into the Amazon Basin. This named outflow is the Casiquiare canal, which, as it heads downstream (southerly), picks up speed and also accumulates water volume.",
"title": "Hydrographic divide"
},
{
"paragraph_id": 12,
"text": "The greatest manifestation of the divide is during floods. During flood stage, the Casiquiare's main outflow point into the Rio Negro is supplemented by an overflow that is a second, and more minor, entry river bifurcation into the Rio Negro and upstream from its major, common low-water entry confluence with the Rio Negro. At flood, the river becomes an area flow source, far more than a narrow confined river.",
"title": "Hydrographic divide"
},
{
"paragraph_id": 13,
"text": "The Casiquiare canal connects the upper Orinoco, 14 kilometres (9 mi) below the mission of Esmeraldas, with the Rio Negro affluent of the Amazon River near the town of San Carlos.",
"title": "Hydrographic divide"
},
{
"paragraph_id": 14,
"text": "The simplest description (besides the entire area-floodplain) of the water divide is a \"south-bank Orinoco River strip\" at the exit point of the Orinoco, also the origin of the Casiquiare canal. However, during the Orinoco's flood stage, that single, simply defined \"origin of the canal\" is turned into a region, and an entire strip along the southern bank of the Orinoco River.",
"title": "Hydrographic divide"
}
] | The Casiquiare river is a distributary of the upper Orinoco flowing southward into the Rio Negro, in Venezuela, South America. As such, it forms a unique natural canal between the Orinoco and Amazon river systems. It is the world's largest river of the kind that links two major river systems, a so-called bifurcation. The area forms a water divide, more dramatically at regional flood stage. | 2001-09-06T14:02:06Z | 2023-09-04T18:34:03Z | [
"Template:IPA-es",
"Template:Sfn",
"Template:Coord",
"Template:Cite news",
"Template:Cite journal",
"Template:Commons category",
"Template:Short description",
"Template:EB1911",
"Template:Infobox river",
"Template:Convert",
"Template:Reflist",
"Template:Cite book",
"Template:Authority control",
"Template:Cite EB1911"
] | https://en.wikipedia.org/wiki/Casiquiare_canal |
6,279 | Capetian dynasty | The Capetian dynasty (/kəˈpiːʃən/; French: Capétiens), also known as the "House of France", is a dynasty of European origin, and a branch of the Robertians. It is among the largest and oldest royal houses in Europe and the world, and consists of Hugh Capet, the founder of the dynasty, and his male-line descendants, who ruled in France without interruption from 987 to 1792, and again from 1814 to 1848. The senior line ruled in France as the House of Capet from the election of Hugh Capet in 987 until the death of Charles IV in 1328. That line was succeeded by cadet branches, the Houses of Valois and then Bourbon, which ruled without interruption until the French Revolution abolished the monarchy in 1792. The Bourbons were restored in 1814 in the aftermath of Napoleon's defeat, but had to vacate the throne again in 1830 in favor of the last Capetian monarch of France, Louis Philippe I, who belonged to the House of Orléans. Cadet branches of the Capetian House of Bourbon are still reigning over Spain and Luxembourg.
The dynasty had a crucial role in the formation of the French state. Initially obeyed only in their own demesne, the Île-de-France, the Capetian kings slowly but steadily increased their power and influence until it grew to cover the entirety of their realm. For a detailed narration on the growth of French royal power, see Crown lands of France.
Members of the dynasty were traditionally Catholic, and the early Capetians had an alliance with the Church. The French were also the most active participants in the Crusades, culminating in a series of five Crusader kings – Louis VII, Philip Augustus, Louis VIII, Louis IX, and Philip III. The Capetian alliance with the papacy suffered a severe blow after the disaster of the Aragonese Crusade. Philip III's son and successor, Philip IV, humiliated Pope Boniface VIII and brought the papacy under French control. The later Valois, starting with Francis I, ignored religious differences and allied with the Ottoman sultan to counter the growing power of the Holy Roman Empire. Henry IV was a Protestant at the time of his accession, but realized the necessity of conversion after four years of religious warfare.
The Capetians generally enjoyed a harmonious family relationship. By tradition, younger sons and brothers of the king of France were given appanages for them to maintain their rank and to dissuade them from claiming the French crown itself. When Capetian cadets did aspire for kingship, their ambitions were directed not at the French throne, but at foreign thrones. As a result, the Capetians have reigned at different times in the kingdoms of Spain, Poland, Aragon, Portugal, Navarre, and as emperors of the Brazilian and Latin empires.
In modern times, King Felipe VI of Spain is a member of this family, while Grand Duke Henri of Luxembourg is related to the family by agnatic kinship; both through the Bourbon branch of the dynasty. Along with the House of Habsburg, arguably its greatest historic rival, it was one of the two oldest European royal dynasties. It was also the most powerful royal family in European history, having played a major role in its politics for much of its existence. According to Oxford University, 75% of all royal families in European history, are related to the Capetian dynasty.
The name of the dynasty derives from its founder, Hugh, who was known as "Hugh Capet". The meaning of "Capet" (a nickname rather than a surname of the modern sort) is unknown. While folk etymology identifies it with "cape", other suggestions indicate it might be connected to the Latin word caput ("head"), and explain it as meaning "chief" or "head".
Historians in the 19th century (see House of France) came to apply the name "Capetian" to both the ruling house of France and to the wider-spread male-line descendants of Hugh Capet. It was not a contemporary practice. The name "Capet" has also been used as a surname for French royalty, particularly but not exclusively those of the House of Capet. One notable use was during the French Revolution, when the dethroned King Louis XVI (a member of the House of Bourbon and a direct male-line descendant of Hugh Capet) and Queen Marie Antoinette (a member of the House of Habsburg-Lorraine) were referred to as "Louis and Antoinette Capet" (the queen being addressed as "the Widow Capet" after the execution of her husband).
The Capetian Miracle (French: Miracle capétien) refers to the dynasty's ability to attain and hold onto the French crown.
In 987, Hugh Capet was elected to succeed Louis V of the Carolingian dynasty that had ruled France for over three centuries. By a process of associating elder sons with them in the kingship, the early Capetians established the hereditary succession in their family and transformed a theoretically electoral kingship into a sacral one. By the time of Philip II Augustus, who became king in 1180, the Capetian hold on power was so strong that the practice of associate kingship was dropped. While the Capetian monarchy began as one of the weakest in Europe, drastically eclipsed by the new Anglo-Norman realm in England (who, as dukes of Normandy, were technically their vassals) and even other great lords of France, the political value of orderly succession in the Middle Ages cannot be overstated. The orderly succession of power from father to son over such a long period of time meant that the French monarchs, who originally were essentially just the direct rulers of the Île-de-France, were able to preserve and extend their power, while over the course of centuries the great peers of the realm would eventually lose their power in one succession crisis or another.
By comparison, the Crusader Kingdom of Jerusalem was constantly beset with internal succession disputes because each generation only produced female heirs who tended to die young. Even the English monarchy encountered severe succession crises, such as The Anarchy of the 1120s between Stephen and Matilda, and the murder of Arthur I, Duke of Brittany, the primogeniture heir of Richard I of England. The latter case would deal a severe blow to the prestige of King John, leading to the eventual destruction of Angevin hegemony in France. In contrast, the French kings were able to maintain uncontested father-to-son succession from the time of Hugh Capet until the succession crisis which began the Hundred Years' War of the 14th century.
The dynastic surname now used to describe Hugh Capet's family prior to his election as King of France is "Robertians" or "Robertines." The name is derived from the family's first certain ancestor, Robert the Strong (b. 820), the count of Paris. Robert was probably son of Robert III of Worms (b. 800) and grandson of Robert of Hesbaye (b. 770). The Robertians probably originated in the county Hesbaye, around Tongeren in modern-day Belgium. The sons of Robert the Strong were Odo and Robert, who both ruled as king of Western Francia. The family became Counts of Paris under Odo and Dukes of the Franks under Robert, possessing large parts of Neustria.
In the late 9th century, King Robert I, grandfather of Hugh Capet, married Beatrice of Vermandois, a direct descendant of Charlemagne, thus making the Capetian dynasty a cadet branch of the Carolingian dynasty.
The Carolingian dynasty ceased to rule France upon the death of Louis V. After the death of Louis V, the son of Hugh the Great, Hugh Capet, was elected by the nobility as king of France. Hugh was crowned at Noyon on 3 July 987 with the full support from Holy Roman Emperor Otto III. With Hugh's coronation, a new era began for France, and his descendants came to be named the Capetians, with the Capetian dynasty and its cadet branches such as the House of Valois ruling France for more than 800 years (987–1848, with some interruptions.
Over the succeeding centuries, Capetians spread throughout Europe, ruling every form of provincial unit from kingdoms to manors.
Salic law, reestablished during the Hundred Years' War from an ancient Frankish tradition, caused the French monarchy to permit only male (agnatic) descendants of Hugh to succeed to the throne of France.
Without Salic law, upon the death of John I, the crown would have passed to his half-sister, Joan (later Joan II of Navarre). However, Joan's paternity was suspect due to her mother's adultery in the Tour de Nesle Affair; the French magnates adopted Salic law to avoid the succession of a possible bastard.
In 1328, King Charles IV of France died without male heirs, as his brothers did before him. Philip of Valois, the late king's first cousin, acted as regent, pending the birth of the king's posthumous child, which proved to be a girl. Isabella of France, sister of Charles IV, claimed the throne for her son, Edward III of England. The English king did not find support among the French lords, who made Philip of Valois their king. From then on the French succession not only excluded females but also rejected claims based on the female line of descent.
Thus the French crown passed from the House of Capet after the death of Charles IV to Philip VI of France of the House of Valois, a cadet branch of the Capetian dynasty,
This did not affect monarchies not under that law such as Portugal, Spain, Navarre, and various smaller duchies and counties. Therefore, many royal families appear and disappear in the French succession or become cadet branches upon marriage. A complete list of the senior-most line of Capetians is available below.
The Capetian dynasty has been broken many times into (sometimes rival) cadet branches. A cadet branch is a line of descent from another line than the senior-most. This list of cadet branches shows most of the Capetian cadet lines and designating their royal French progenitor, although some sub-branches are not shown.
Throughout most of history, the Senior Capet and the King of France were synonymous terms. Only in the time before Hugh Capet took the crown for himself and after the reign of Charles X is there a distinction such that the senior Capet must be identified independently from succession to the French Crown. However, since primogeniture and the Salic law provided for the succession of the French throne for most of French history, here is a list of all the French kings from Hugh until Charles, and all the Legitimist pretenders thereafter. All dates are for seniority, not reign.
King of France:
Legitimist Pretenders:
Many years have passed since the Capetian monarchs ruled a large part of Europe; however, they still remain as kings, as well as other titles. Currently two Capetian monarchs still rule in Spain and Luxembourg. In addition, seven pretenders represent exiled dynastic monarchies in Brazil, France, Spain, Portugal, Parma and Two Sicilies. The current legitimate, senior family member is Louis-Alphonse de Bourbon, known by his supporters as Duke of Anjou, who also holds the Legitimist (Blancs d'Espagne) claim to the French throne. Overall, dozens of branches of the Capetian dynasty still exist throughout Europe.
Except for the House of Braganza (founded by an illegitimate son of King John I of Portugal, who was himself illegitimate), all current major Capetian branches are of the Bourbon cadet branch. Within the House of Bourbon, many of these lines are themselves well-defined cadet lines of the House. | [
{
"paragraph_id": 0,
"text": "The Capetian dynasty (/kəˈpiːʃən/; French: Capétiens), also known as the \"House of France\", is a dynasty of European origin, and a branch of the Robertians. It is among the largest and oldest royal houses in Europe and the world, and consists of Hugh Capet, the founder of the dynasty, and his male-line descendants, who ruled in France without interruption from 987 to 1792, and again from 1814 to 1848. The senior line ruled in France as the House of Capet from the election of Hugh Capet in 987 until the death of Charles IV in 1328. That line was succeeded by cadet branches, the Houses of Valois and then Bourbon, which ruled without interruption until the French Revolution abolished the monarchy in 1792. The Bourbons were restored in 1814 in the aftermath of Napoleon's defeat, but had to vacate the throne again in 1830 in favor of the last Capetian monarch of France, Louis Philippe I, who belonged to the House of Orléans. Cadet branches of the Capetian House of Bourbon are still reigning over Spain and Luxembourg.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The dynasty had a crucial role in the formation of the French state. Initially obeyed only in their own demesne, the Île-de-France, the Capetian kings slowly but steadily increased their power and influence until it grew to cover the entirety of their realm. For a detailed narration on the growth of French royal power, see Crown lands of France.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Members of the dynasty were traditionally Catholic, and the early Capetians had an alliance with the Church. The French were also the most active participants in the Crusades, culminating in a series of five Crusader kings – Louis VII, Philip Augustus, Louis VIII, Louis IX, and Philip III. The Capetian alliance with the papacy suffered a severe blow after the disaster of the Aragonese Crusade. Philip III's son and successor, Philip IV, humiliated Pope Boniface VIII and brought the papacy under French control. The later Valois, starting with Francis I, ignored religious differences and allied with the Ottoman sultan to counter the growing power of the Holy Roman Empire. Henry IV was a Protestant at the time of his accession, but realized the necessity of conversion after four years of religious warfare.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The Capetians generally enjoyed a harmonious family relationship. By tradition, younger sons and brothers of the king of France were given appanages for them to maintain their rank and to dissuade them from claiming the French crown itself. When Capetian cadets did aspire for kingship, their ambitions were directed not at the French throne, but at foreign thrones. As a result, the Capetians have reigned at different times in the kingdoms of Spain, Poland, Aragon, Portugal, Navarre, and as emperors of the Brazilian and Latin empires.",
"title": ""
},
{
"paragraph_id": 4,
"text": "In modern times, King Felipe VI of Spain is a member of this family, while Grand Duke Henri of Luxembourg is related to the family by agnatic kinship; both through the Bourbon branch of the dynasty. Along with the House of Habsburg, arguably its greatest historic rival, it was one of the two oldest European royal dynasties. It was also the most powerful royal family in European history, having played a major role in its politics for much of its existence. According to Oxford University, 75% of all royal families in European history, are related to the Capetian dynasty.",
"title": ""
},
{
"paragraph_id": 5,
"text": "The name of the dynasty derives from its founder, Hugh, who was known as \"Hugh Capet\". The meaning of \"Capet\" (a nickname rather than a surname of the modern sort) is unknown. While folk etymology identifies it with \"cape\", other suggestions indicate it might be connected to the Latin word caput (\"head\"), and explain it as meaning \"chief\" or \"head\".",
"title": "Name origins and usage"
},
{
"paragraph_id": 6,
"text": "Historians in the 19th century (see House of France) came to apply the name \"Capetian\" to both the ruling house of France and to the wider-spread male-line descendants of Hugh Capet. It was not a contemporary practice. The name \"Capet\" has also been used as a surname for French royalty, particularly but not exclusively those of the House of Capet. One notable use was during the French Revolution, when the dethroned King Louis XVI (a member of the House of Bourbon and a direct male-line descendant of Hugh Capet) and Queen Marie Antoinette (a member of the House of Habsburg-Lorraine) were referred to as \"Louis and Antoinette Capet\" (the queen being addressed as \"the Widow Capet\" after the execution of her husband).",
"title": "Name origins and usage"
},
{
"paragraph_id": 7,
"text": "The Capetian Miracle (French: Miracle capétien) refers to the dynasty's ability to attain and hold onto the French crown.",
"title": "Capetian miracle"
},
{
"paragraph_id": 8,
"text": "In 987, Hugh Capet was elected to succeed Louis V of the Carolingian dynasty that had ruled France for over three centuries. By a process of associating elder sons with them in the kingship, the early Capetians established the hereditary succession in their family and transformed a theoretically electoral kingship into a sacral one. By the time of Philip II Augustus, who became king in 1180, the Capetian hold on power was so strong that the practice of associate kingship was dropped. While the Capetian monarchy began as one of the weakest in Europe, drastically eclipsed by the new Anglo-Norman realm in England (who, as dukes of Normandy, were technically their vassals) and even other great lords of France, the political value of orderly succession in the Middle Ages cannot be overstated. The orderly succession of power from father to son over such a long period of time meant that the French monarchs, who originally were essentially just the direct rulers of the Île-de-France, were able to preserve and extend their power, while over the course of centuries the great peers of the realm would eventually lose their power in one succession crisis or another.",
"title": "Capetian miracle"
},
{
"paragraph_id": 9,
"text": "By comparison, the Crusader Kingdom of Jerusalem was constantly beset with internal succession disputes because each generation only produced female heirs who tended to die young. Even the English monarchy encountered severe succession crises, such as The Anarchy of the 1120s between Stephen and Matilda, and the murder of Arthur I, Duke of Brittany, the primogeniture heir of Richard I of England. The latter case would deal a severe blow to the prestige of King John, leading to the eventual destruction of Angevin hegemony in France. In contrast, the French kings were able to maintain uncontested father-to-son succession from the time of Hugh Capet until the succession crisis which began the Hundred Years' War of the 14th century.",
"title": "Capetian miracle"
},
{
"paragraph_id": 10,
"text": "The dynastic surname now used to describe Hugh Capet's family prior to his election as King of France is \"Robertians\" or \"Robertines.\" The name is derived from the family's first certain ancestor, Robert the Strong (b. 820), the count of Paris. Robert was probably son of Robert III of Worms (b. 800) and grandson of Robert of Hesbaye (b. 770). The Robertians probably originated in the county Hesbaye, around Tongeren in modern-day Belgium. The sons of Robert the Strong were Odo and Robert, who both ruled as king of Western Francia. The family became Counts of Paris under Odo and Dukes of the Franks under Robert, possessing large parts of Neustria.",
"title": "The Robertians and before"
},
{
"paragraph_id": 11,
"text": "In the late 9th century, King Robert I, grandfather of Hugh Capet, married Beatrice of Vermandois, a direct descendant of Charlemagne, thus making the Capetian dynasty a cadet branch of the Carolingian dynasty.",
"title": "The Robertians and before"
},
{
"paragraph_id": 12,
"text": "The Carolingian dynasty ceased to rule France upon the death of Louis V. After the death of Louis V, the son of Hugh the Great, Hugh Capet, was elected by the nobility as king of France. Hugh was crowned at Noyon on 3 July 987 with the full support from Holy Roman Emperor Otto III. With Hugh's coronation, a new era began for France, and his descendants came to be named the Capetians, with the Capetian dynasty and its cadet branches such as the House of Valois ruling France for more than 800 years (987–1848, with some interruptions.",
"title": "The Robertians and before"
},
{
"paragraph_id": 13,
"text": "Over the succeeding centuries, Capetians spread throughout Europe, ruling every form of provincial unit from kingdoms to manors.",
"title": "Capetians through history"
},
{
"paragraph_id": 14,
"text": "Salic law, reestablished during the Hundred Years' War from an ancient Frankish tradition, caused the French monarchy to permit only male (agnatic) descendants of Hugh to succeed to the throne of France.",
"title": "Capetians through history"
},
{
"paragraph_id": 15,
"text": "Without Salic law, upon the death of John I, the crown would have passed to his half-sister, Joan (later Joan II of Navarre). However, Joan's paternity was suspect due to her mother's adultery in the Tour de Nesle Affair; the French magnates adopted Salic law to avoid the succession of a possible bastard.",
"title": "Capetians through history"
},
{
"paragraph_id": 16,
"text": "In 1328, King Charles IV of France died without male heirs, as his brothers did before him. Philip of Valois, the late king's first cousin, acted as regent, pending the birth of the king's posthumous child, which proved to be a girl. Isabella of France, sister of Charles IV, claimed the throne for her son, Edward III of England. The English king did not find support among the French lords, who made Philip of Valois their king. From then on the French succession not only excluded females but also rejected claims based on the female line of descent.",
"title": "Capetians through history"
},
{
"paragraph_id": 17,
"text": "Thus the French crown passed from the House of Capet after the death of Charles IV to Philip VI of France of the House of Valois, a cadet branch of the Capetian dynasty,",
"title": "Capetians through history"
},
{
"paragraph_id": 18,
"text": "This did not affect monarchies not under that law such as Portugal, Spain, Navarre, and various smaller duchies and counties. Therefore, many royal families appear and disappear in the French succession or become cadet branches upon marriage. A complete list of the senior-most line of Capetians is available below.",
"title": "Capetians through history"
},
{
"paragraph_id": 19,
"text": "The Capetian dynasty has been broken many times into (sometimes rival) cadet branches. A cadet branch is a line of descent from another line than the senior-most. This list of cadet branches shows most of the Capetian cadet lines and designating their royal French progenitor, although some sub-branches are not shown.",
"title": "Capetians through history"
},
{
"paragraph_id": 20,
"text": "Throughout most of history, the Senior Capet and the King of France were synonymous terms. Only in the time before Hugh Capet took the crown for himself and after the reign of Charles X is there a distinction such that the senior Capet must be identified independently from succession to the French Crown. However, since primogeniture and the Salic law provided for the succession of the French throne for most of French history, here is a list of all the French kings from Hugh until Charles, and all the Legitimist pretenders thereafter. All dates are for seniority, not reign.",
"title": "Senior Capets"
},
{
"paragraph_id": 21,
"text": "King of France:",
"title": "Senior Capets"
},
{
"paragraph_id": 22,
"text": "Legitimist Pretenders:",
"title": "Senior Capets"
},
{
"paragraph_id": 23,
"text": "Many years have passed since the Capetian monarchs ruled a large part of Europe; however, they still remain as kings, as well as other titles. Currently two Capetian monarchs still rule in Spain and Luxembourg. In addition, seven pretenders represent exiled dynastic monarchies in Brazil, France, Spain, Portugal, Parma and Two Sicilies. The current legitimate, senior family member is Louis-Alphonse de Bourbon, known by his supporters as Duke of Anjou, who also holds the Legitimist (Blancs d'Espagne) claim to the French throne. Overall, dozens of branches of the Capetian dynasty still exist throughout Europe.",
"title": "The Capetian dynasty today"
},
{
"paragraph_id": 24,
"text": "Except for the House of Braganza (founded by an illegitimate son of King John I of Portugal, who was himself illegitimate), all current major Capetian branches are of the Bourbon cadet branch. Within the House of Bourbon, many of these lines are themselves well-defined cadet lines of the House.",
"title": "The Capetian dynasty today"
}
] | The Capetian dynasty, also known as the "House of France", is a dynasty of European origin, and a branch of the Robertians. It is among the largest and oldest royal houses in Europe and the world, and consists of Hugh Capet, the founder of the dynasty, and his male-line descendants, who ruled in France without interruption from 987 to 1792, and again from 1814 to 1848. The senior line ruled in France as the House of Capet from the election of Hugh Capet in 987 until the death of Charles IV in 1328. That line was succeeded by cadet branches, the Houses of Valois and then Bourbon, which ruled without interruption until the French Revolution abolished the monarchy in 1792. The Bourbons were restored in 1814 in the aftermath of Napoleon's defeat, but had to vacate the throne again in 1830 in favor of the last Capetian monarch of France, Louis Philippe I, who belonged to the House of Orléans.
Cadet branches of the Capetian House of Bourbon are still reigning over Spain and Luxembourg. The dynasty had a crucial role in the formation of the French state. Initially obeyed only in their own demesne, the Île-de-France, the Capetian kings slowly but steadily increased their power and influence until it grew to cover the entirety of their realm. For a detailed narration on the growth of French royal power, see Crown lands of France. Members of the dynasty were traditionally Catholic, and the early Capetians had an alliance with the Church. The French were also the most active participants in the Crusades, culminating in a series of five Crusader kings – Louis VII, Philip Augustus, Louis VIII, Louis IX, and Philip III. The Capetian alliance with the papacy suffered a severe blow after the disaster of the Aragonese Crusade. Philip III's son and successor, Philip IV, humiliated Pope Boniface VIII and brought the papacy under French control. The later Valois, starting with Francis I, ignored religious differences and allied with the Ottoman sultan to counter the growing power of the Holy Roman Empire. Henry IV was a Protestant at the time of his accession, but realized the necessity of conversion after four years of religious warfare. The Capetians generally enjoyed a harmonious family relationship. By tradition, younger sons and brothers of the king of France were given appanages for them to maintain their rank and to dissuade them from claiming the French crown itself. When Capetian cadets did aspire for kingship, their ambitions were directed not at the French throne, but at foreign thrones. As a result, the Capetians have reigned at different times in the kingdoms of Spain, Poland, Aragon, Portugal, Navarre, and as emperors of the Brazilian and Latin empires. In modern times, King Felipe VI of Spain is a member of this family, while Grand Duke Henri of Luxembourg is related to the family by agnatic kinship; both through the Bourbon branch of the dynasty. Along with the House of Habsburg, arguably its greatest historic rival, it was one of the two oldest European royal dynasties. It was also the most powerful royal family in European history, having played a major role in its politics for much of its existence. According to Oxford University, 75% of all royal families in European history, are related to the Capetian dynasty. | 2001-09-06T20:54:25Z | 2023-12-21T03:52:48Z | [
"Template:See also",
"Template:Reflist",
"Template:Short description",
"Template:Royal house",
"Template:Refimprove section",
"Template:Capetian Cadets",
"Template:Tree list",
"Template:More footnotes",
"Template:Unreferenced section",
"Template:Cite book",
"Template:IPAc-en",
"Template:Lang-fr",
"Template:Citation needed",
"Template:Refn",
"Template:Tree list/final branch",
"Template:Cn",
"Template:Royal houses of France",
"Template:For",
"Template:Sfn",
"Template:Page needed",
"Template:Multiple image",
"Template:In lang",
"Template:Main",
"Template:Use dmy dates",
"Template:Tree list/end",
"Template:ISBN",
"Template:Authority control"
] | https://en.wikipedia.org/wiki/Capetian_dynasty |
6,280 | Cuboctahedron | A cuboctahedron is a polyhedron with 8 triangular faces and 6 square faces. A cuboctahedron has 12 identical vertices, with 2 triangles and 2 squares meeting at each, and 24 identical edges, each separating a triangle from a square. As such, it is a quasiregular polyhedron, i.e. an Archimedean solid that is not only vertex-transitive but also edge-transitive. It is radially equilateral.
Its dual polyhedron is the rhombic dodecahedron.
The cuboctahedron was probably known to Plato: Heron's Definitiones quotes Archimedes as saying that Plato knew of a solid made of 8 triangles and 6 squares.
The cuboctahedron has four special orthogonal projections, centered on a vertex, an edge, and the two types of faces, triangular and square. The last two correspond to the B2 and A2 Coxeter planes. The skew projections show a square and hexagon passing through the center of the cuboctahedron.
The cuboctahedron can also be represented as a spherical tiling, and projected onto the plane via a stereographic projection. This projection is conformal, preserving angles but not areas or lengths. Straight lines on the sphere are projected as circular arcs on the plane.
The Cartesian coordinates for the vertices of a cuboctahedron (of edge length √2) centered at the origin are:
An alternate set of coordinates can be made in 4-space, as 12 permutations of:
This construction exists as one of 16 orthant facets of the cantellated 16-cell.
The cuboctahedron's 12 vertices can represent the root vectors of the simple Lie group A3. With the addition of 6 vertices of the octahedron, these vertices represent the 18 root vectors of the simple Lie group B3.
The area A and the volume V of the cuboctahedron of edge length a are:
The cuboctahedron can be dissected into 6 square pyramids and 8 tetrahedra meeting at a central point. This dissection is expressed in the tetrahedral-octahedral honeycomb where pairs of square pyramids are combined into octahedra.
The cuboctahedron can be dissected into two triangular cupolas by a common hexagon passing through the center of the cuboctahedron. If these two triangular cupolas are twisted so triangles and squares line up, Johnson solid J27, the triangular orthobicupola, is created.
In a cuboctahedron, the long radius (center to vertex) is the same as the edge length; thus its long diameter (vertex to opposite vertex) is 2 edge lengths. Its center is like the apical vertex of a pyramid: one edge length away from all the other vertices. (In the case of the cuboctahedron, the center is in fact the apex of 6 square and 8 triangular pyramids). This radial equilateral symmetry is a property of only a few uniform polytopes, including the two-dimensional hexagon, the three-dimensional cuboctahedron, and the four-dimensional 24-cell and 8-cell (tesseract). Radially equilateral polytopes are those which can be constructed, with their long radii, from equilateral triangles which meet at the center of the polytope, each contributing two radii and an edge. Therefore, all the interior elements which meet at the center of these polytopes have equilateral triangle inward faces, as in the dissection of the cuboctahedron into 6 square pyramids and 8 tetrahedra.
Each of these radially equilateral polytopes also occurs as cells of a characteristic space-filling tessellation: the tiling of regular hexagons, the rectified cubic honeycomb (of alternating cuboctahedra and octahedra), the 24-cell honeycomb and the tesseractic honeycomb, respectively. Each tessellation has a dual tessellation; the cell centers in a tessellation are cell vertices in its dual tessellation. The densest known regular sphere-packing in two, three and four dimensions uses the cell centers of one of these tessellations as sphere centers.
A cuboctahedron has octahedral symmetry. Its first stellation is the compound of a cube and its dual octahedron, with the vertices of the cuboctahedron located at the midpoints of the edges of either.
A cuboctahedron can be obtained by taking an equatorial cross section of a four-dimensional 24-cell or 16-cell. A hexagon or a square can be obtained by taking an equatorial cross section of a cuboctahedron.
The cuboctahedron is a rectified cube and also a rectified octahedron.
It is also a cantellated tetrahedron. With this construction it is given the Wythoff symbol: 3 3 | 2.
A skew cantellation of the tetrahedron produces a solid with faces parallel to those of the cuboctahedron, namely eight triangles of two sizes, and six rectangles. While its edges are unequal, this solid remains vertex-uniform: the solid has the full tetrahedral symmetry group and its vertices are equivalent under that group.
The edges of a cuboctahedron form four regular hexagons. If the cuboctahedron is cut in the plane of one of these hexagons, each half is a triangular cupola, one of the Johnson solids; the cuboctahedron itself thus can also be called a triangular gyrobicupola, the simplest of a series (other than the gyrobifastigium or "digonal gyrobicupola"). If the halves are put back together with a twist, so that triangles meet triangles and squares meet squares, the result is another Johnson solid, the triangular orthobicupola, also called an anticuboctahedron.
Both triangular bicupolae are important in sphere packing. The distance from the solid's center to its vertices is equal to its edge length. Each central sphere can have up to twelve neighbors, and in a face-centered cubic lattice these take the positions of a cuboctahedron's vertices. In a hexagonal close-packed lattice they correspond to the corners of the triangular orthobicupola. In both cases the central sphere takes the position of the solid's center.
Cuboctahedra appear as cells in three of the convex uniform honeycombs and in nine of the convex uniform 4-polytopes.
The volume of the cuboctahedron is 5/6 of that of the enclosing cube and 5/8 of that of the enclosing octahedron.
Because it is radially equilateral, the cuboctahedron's center can be treated as a 13th canonical apical vertex, one edge length distant from the 12 ordinary vertices, as the apex of a canonical pyramid is one edge length equidistant from its other vertices.
The cuboctahedron shares its edges and vertex arrangement with two nonconvex uniform polyhedra: the cubohemioctahedron (having the square faces in common) and the octahemioctahedron (having the triangular faces in common), both have four hexagons. It also serves as a cantellated tetrahedron, as being a rectified tetratetrahedron.
The cuboctahedron 2-covers the tetrahemihexahedron, which accordingly has the same abstract vertex figure (two triangles and two squares: 3.4.3.4) and half the vertices, edges, and faces. (The actual vertex figure of the tetrahemihexahedron is 3.4.3/2.4, with the a/2 factor due to the cross.)
When interpreted as a framework of rigid flat faces, connected along the edges by hinges, the cuboctahedron is a rigid structure, as are all convex polyhedra, by Cauchy's theorem. However, when the faces are removed, leaving only rigid edges connected by flexible joints at the vertices, the result is not a rigid system (unlike polyhedra whose faces are all triangles, to which Cauchy's theorem applies despite the missing faces).
Adding a central vertex, connected by rigid edges to all the other vertices, subdivides the cuboctahedron into square pyramids and tetrahedra, meeting at the central vertex. Unlike the cuboctahedron itself, the resulting system of edges and joints is rigid, and forms part of the infinite octet truss structure.
The cuboctahedron is one of a family of uniform polyhedra related to the cube and regular octahedron.
The cuboctahedron also has tetrahedral symmetry with two colors of triangles.
The cuboctahedron exists in a sequence of symmetries of quasiregular polyhedra and tilings with vertex configurations (3.n), progressing from tilings of the sphere to the Euclidean plane and into the hyperbolic plane. With orbifold notation symmetry of *n32 all of these tilings are wythoff construction within a fundamental domain of symmetry, with generator points at the right angle corner of the domain.
This polyhedron is topologically related as a part of sequence of cantellated polyhedra with vertex figure (3.4.n.4), and continues as tilings of the hyperbolic plane. These vertex-transitive figures have (*n32) reflectional symmetry.
The cuboctahedron can be decomposed into a regular octahedron and eight irregular but equal octahedra in the shape of the convex hull of a cube with two opposite vertices removed. This decomposition of the cuboctahedron corresponds with the cell-first parallel projection of the 24-cell into three dimensions. Under this projection, the cuboctahedron forms the projection envelope, which can be decomposed into six square faces, a regular octahedron, and eight irregular octahedra. These elements correspond with the images of six of the octahedral cells in the 24-cell, the nearest and farthest cells from the 4D viewpoint, and the remaining eight pairs of cells, respectively.
In the mathematical field of graph theory, a cuboctahedral graph is the graph of vertices and edges of the cuboctahedron, one of the Archimedean solids. It can also be constructed as the line graph of the cube. It has 12 vertices and 24 edges, is locally linear, and is a quartic Archimedean graph. | [
{
"paragraph_id": 0,
"text": "A cuboctahedron is a polyhedron with 8 triangular faces and 6 square faces. A cuboctahedron has 12 identical vertices, with 2 triangles and 2 squares meeting at each, and 24 identical edges, each separating a triangle from a square. As such, it is a quasiregular polyhedron, i.e. an Archimedean solid that is not only vertex-transitive but also edge-transitive. It is radially equilateral.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Its dual polyhedron is the rhombic dodecahedron.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The cuboctahedron was probably known to Plato: Heron's Definitiones quotes Archimedes as saying that Plato knew of a solid made of 8 triangles and 6 squares.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The cuboctahedron has four special orthogonal projections, centered on a vertex, an edge, and the two types of faces, triangular and square. The last two correspond to the B2 and A2 Coxeter planes. The skew projections show a square and hexagon passing through the center of the cuboctahedron.",
"title": "Orthogonal projections"
},
{
"paragraph_id": 4,
"text": "The cuboctahedron can also be represented as a spherical tiling, and projected onto the plane via a stereographic projection. This projection is conformal, preserving angles but not areas or lengths. Straight lines on the sphere are projected as circular arcs on the plane.",
"title": "Spherical tiling"
},
{
"paragraph_id": 5,
"text": "The Cartesian coordinates for the vertices of a cuboctahedron (of edge length √2) centered at the origin are:",
"title": "Structure"
},
{
"paragraph_id": 6,
"text": "An alternate set of coordinates can be made in 4-space, as 12 permutations of:",
"title": "Structure"
},
{
"paragraph_id": 7,
"text": "This construction exists as one of 16 orthant facets of the cantellated 16-cell.",
"title": "Structure"
},
{
"paragraph_id": 8,
"text": "The cuboctahedron's 12 vertices can represent the root vectors of the simple Lie group A3. With the addition of 6 vertices of the octahedron, these vertices represent the 18 root vectors of the simple Lie group B3.",
"title": "Structure"
},
{
"paragraph_id": 9,
"text": "The area A and the volume V of the cuboctahedron of edge length a are:",
"title": "Structure"
},
{
"paragraph_id": 10,
"text": "The cuboctahedron can be dissected into 6 square pyramids and 8 tetrahedra meeting at a central point. This dissection is expressed in the tetrahedral-octahedral honeycomb where pairs of square pyramids are combined into octahedra.",
"title": "Dissection"
},
{
"paragraph_id": 11,
"text": "The cuboctahedron can be dissected into two triangular cupolas by a common hexagon passing through the center of the cuboctahedron. If these two triangular cupolas are twisted so triangles and squares line up, Johnson solid J27, the triangular orthobicupola, is created.",
"title": "Dissection"
},
{
"paragraph_id": 12,
"text": "In a cuboctahedron, the long radius (center to vertex) is the same as the edge length; thus its long diameter (vertex to opposite vertex) is 2 edge lengths. Its center is like the apical vertex of a pyramid: one edge length away from all the other vertices. (In the case of the cuboctahedron, the center is in fact the apex of 6 square and 8 triangular pyramids). This radial equilateral symmetry is a property of only a few uniform polytopes, including the two-dimensional hexagon, the three-dimensional cuboctahedron, and the four-dimensional 24-cell and 8-cell (tesseract). Radially equilateral polytopes are those which can be constructed, with their long radii, from equilateral triangles which meet at the center of the polytope, each contributing two radii and an edge. Therefore, all the interior elements which meet at the center of these polytopes have equilateral triangle inward faces, as in the dissection of the cuboctahedron into 6 square pyramids and 8 tetrahedra.",
"title": "Geometric relations"
},
{
"paragraph_id": 13,
"text": "Each of these radially equilateral polytopes also occurs as cells of a characteristic space-filling tessellation: the tiling of regular hexagons, the rectified cubic honeycomb (of alternating cuboctahedra and octahedra), the 24-cell honeycomb and the tesseractic honeycomb, respectively. Each tessellation has a dual tessellation; the cell centers in a tessellation are cell vertices in its dual tessellation. The densest known regular sphere-packing in two, three and four dimensions uses the cell centers of one of these tessellations as sphere centers.",
"title": "Geometric relations"
},
{
"paragraph_id": 14,
"text": "A cuboctahedron has octahedral symmetry. Its first stellation is the compound of a cube and its dual octahedron, with the vertices of the cuboctahedron located at the midpoints of the edges of either.",
"title": "Geometric relations"
},
{
"paragraph_id": 15,
"text": "A cuboctahedron can be obtained by taking an equatorial cross section of a four-dimensional 24-cell or 16-cell. A hexagon or a square can be obtained by taking an equatorial cross section of a cuboctahedron.",
"title": "Geometric relations"
},
{
"paragraph_id": 16,
"text": "The cuboctahedron is a rectified cube and also a rectified octahedron.",
"title": "Geometric relations"
},
{
"paragraph_id": 17,
"text": "It is also a cantellated tetrahedron. With this construction it is given the Wythoff symbol: 3 3 | 2.",
"title": "Geometric relations"
},
{
"paragraph_id": 18,
"text": "A skew cantellation of the tetrahedron produces a solid with faces parallel to those of the cuboctahedron, namely eight triangles of two sizes, and six rectangles. While its edges are unequal, this solid remains vertex-uniform: the solid has the full tetrahedral symmetry group and its vertices are equivalent under that group.",
"title": "Geometric relations"
},
{
"paragraph_id": 19,
"text": "The edges of a cuboctahedron form four regular hexagons. If the cuboctahedron is cut in the plane of one of these hexagons, each half is a triangular cupola, one of the Johnson solids; the cuboctahedron itself thus can also be called a triangular gyrobicupola, the simplest of a series (other than the gyrobifastigium or \"digonal gyrobicupola\"). If the halves are put back together with a twist, so that triangles meet triangles and squares meet squares, the result is another Johnson solid, the triangular orthobicupola, also called an anticuboctahedron.",
"title": "Geometric relations"
},
{
"paragraph_id": 20,
"text": "Both triangular bicupolae are important in sphere packing. The distance from the solid's center to its vertices is equal to its edge length. Each central sphere can have up to twelve neighbors, and in a face-centered cubic lattice these take the positions of a cuboctahedron's vertices. In a hexagonal close-packed lattice they correspond to the corners of the triangular orthobicupola. In both cases the central sphere takes the position of the solid's center.",
"title": "Geometric relations"
},
{
"paragraph_id": 21,
"text": "Cuboctahedra appear as cells in three of the convex uniform honeycombs and in nine of the convex uniform 4-polytopes.",
"title": "Geometric relations"
},
{
"paragraph_id": 22,
"text": "The volume of the cuboctahedron is 5/6 of that of the enclosing cube and 5/8 of that of the enclosing octahedron.",
"title": "Geometric relations"
},
{
"paragraph_id": 23,
"text": "Because it is radially equilateral, the cuboctahedron's center can be treated as a 13th canonical apical vertex, one edge length distant from the 12 ordinary vertices, as the apex of a canonical pyramid is one edge length equidistant from its other vertices.",
"title": "Geometric relations"
},
{
"paragraph_id": 24,
"text": "The cuboctahedron shares its edges and vertex arrangement with two nonconvex uniform polyhedra: the cubohemioctahedron (having the square faces in common) and the octahemioctahedron (having the triangular faces in common), both have four hexagons. It also serves as a cantellated tetrahedron, as being a rectified tetratetrahedron.",
"title": "Geometric relations"
},
{
"paragraph_id": 25,
"text": "The cuboctahedron 2-covers the tetrahemihexahedron, which accordingly has the same abstract vertex figure (two triangles and two squares: 3.4.3.4) and half the vertices, edges, and faces. (The actual vertex figure of the tetrahemihexahedron is 3.4.3/2.4, with the a/2 factor due to the cross.)",
"title": "Geometric relations"
},
{
"paragraph_id": 26,
"text": "When interpreted as a framework of rigid flat faces, connected along the edges by hinges, the cuboctahedron is a rigid structure, as are all convex polyhedra, by Cauchy's theorem. However, when the faces are removed, leaving only rigid edges connected by flexible joints at the vertices, the result is not a rigid system (unlike polyhedra whose faces are all triangles, to which Cauchy's theorem applies despite the missing faces).",
"title": "Geometric relations"
},
{
"paragraph_id": 27,
"text": "Adding a central vertex, connected by rigid edges to all the other vertices, subdivides the cuboctahedron into square pyramids and tetrahedra, meeting at the central vertex. Unlike the cuboctahedron itself, the resulting system of edges and joints is rigid, and forms part of the infinite octet truss structure.",
"title": "Geometric relations"
},
{
"paragraph_id": 28,
"text": "The cuboctahedron is one of a family of uniform polyhedra related to the cube and regular octahedron.",
"title": "Related polytopes"
},
{
"paragraph_id": 29,
"text": "The cuboctahedron also has tetrahedral symmetry with two colors of triangles.",
"title": "Related polytopes"
},
{
"paragraph_id": 30,
"text": "The cuboctahedron exists in a sequence of symmetries of quasiregular polyhedra and tilings with vertex configurations (3.n), progressing from tilings of the sphere to the Euclidean plane and into the hyperbolic plane. With orbifold notation symmetry of *n32 all of these tilings are wythoff construction within a fundamental domain of symmetry, with generator points at the right angle corner of the domain.",
"title": "Related polytopes"
},
{
"paragraph_id": 31,
"text": "This polyhedron is topologically related as a part of sequence of cantellated polyhedra with vertex figure (3.4.n.4), and continues as tilings of the hyperbolic plane. These vertex-transitive figures have (*n32) reflectional symmetry.",
"title": "Related polytopes"
},
{
"paragraph_id": 32,
"text": "The cuboctahedron can be decomposed into a regular octahedron and eight irregular but equal octahedra in the shape of the convex hull of a cube with two opposite vertices removed. This decomposition of the cuboctahedron corresponds with the cell-first parallel projection of the 24-cell into three dimensions. Under this projection, the cuboctahedron forms the projection envelope, which can be decomposed into six square faces, a regular octahedron, and eight irregular octahedra. These elements correspond with the images of six of the octahedral cells in the 24-cell, the nearest and farthest cells from the 4D viewpoint, and the remaining eight pairs of cells, respectively.",
"title": "Related polytopes"
},
{
"paragraph_id": 33,
"text": "In the mathematical field of graph theory, a cuboctahedral graph is the graph of vertices and edges of the cuboctahedron, one of the Archimedean solids. It can also be constructed as the line graph of the cube. It has 12 vertices and 24 edges, is locally linear, and is a quartic Archimedean graph.",
"title": "Cuboctahedral graph"
}
] | A cuboctahedron is a polyhedron with 8 triangular faces and 6 square faces. A cuboctahedron has 12 identical vertices, with 2 triangles and 2 squares meeting at each, and 24 identical edges, each separating a triangle from a square. As such, it is a quasiregular polyhedron, i.e. an Archimedean solid that is not only vertex-transitive but also edge-transitive. It is radially equilateral. Its dual polyhedron is the rhombic dodecahedron. The cuboctahedron was probably known to Plato: Heron's Definitiones quotes Archimedes as saying that Plato knew of a solid made of 8 triangles and 6 squares. | 2001-11-09T04:20:18Z | 2023-08-28T02:24:12Z | [
"Template:Quasiregular4 table",
"Template:Infobox graph",
"Template:Cite web",
"Template:Citation",
"Template:KlitzingPolytopes",
"Template:Nowrap",
"Template:Tetrahedron family",
"Template:Quasiregular3 small table",
"Template:Archimedean solids",
"Template:Reflist",
"Template:Refend",
"Template:Polyhedron navigator",
"Template:Efn",
"Template:Cite encyclopedia",
"Template:Sfn",
"Template:Main",
"Template:Clear",
"Template:Short description",
"Template:Semireg polyhedra db",
"Template:Sqrt",
"Template:Notelist",
"Template:Cite book",
"Template:Sfrac",
"Template:Octahedral truncations",
"Template:Expanded small table",
"Template:Refbegin",
"Template:The Geometrical Foundation of Natural Structure (book)",
"Template:Mathworld2"
] | https://en.wikipedia.org/wiki/Cuboctahedron |
6,281 | Canton | Canton may refer to: | [
{
"paragraph_id": 0,
"text": "Canton may refer to:",
"title": ""
}
] | Canton may refer to: | 2001-09-07T01:47:33Z | 2023-11-09T17:48:31Z | [
"Template:Disambiguation",
"Template:Wiktionary",
"Template:TOC right"
] | https://en.wikipedia.org/wiki/Canton |
6,282 | Class | Class, Classes, or The Class may refer to: | [
{
"paragraph_id": 0,
"text": "Class, Classes, or The Class may refer to:",
"title": ""
}
] | Class, Classes, or The Class may refer to: | 2001-10-25T00:16:34Z | 2023-12-09T04:28:55Z | [
"Template:Wiktionary",
"Template:TOC right",
"Template:Disambiguation"
] | https://en.wikipedia.org/wiki/Class |
6,283 | Critical point | Critical point may refer to: | [
{
"paragraph_id": 0,
"text": "Critical point may refer to:",
"title": ""
}
] | Critical point may refer to: Critical phenomena in physics
Critical point (mathematics), in calculus, a point where a function's derivative is either zero or nonexistent
Critical point, an elementary embedding of a transitive class into another transitive class which is the smallest ordinal which is not mapped to itself
Critical point (thermodynamics), a temperature and pressure of a material beyond which there is no longer any difference between the liquid and gas phases
Quantum critical point
Critical point
Construction point, in skiing, a line that represents the steepest point on a hill | 2023-02-14T02:39:09Z | [
"Template:Wiktionary",
"Template:Disambiguation"
] | https://en.wikipedia.org/wiki/Critical_point |
|
6,285 | Cube | In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets, or sides, with three meeting at each vertex. Viewed from a corner, it is a hexagon and its net is usually depicted as a cross.
The cube is the only regular hexahedron and is one of the five Platonic solids. It has 6 faces, 12 edges, and 8 vertices.
The cube is also a square parallelepiped, an equilateral cuboid, a right rhombohedron, and a 3-zonohedron. It is a regular square prism in three orientations, and a trigonal trapezohedron in four orientations.
The cube is dual to the octahedron. It has cubical or octahedral symmetry, and is the only convex polyhedron whose faces are all squares. Its generalization for higher-dimensional spaces is called a hypercube.
The cube has four special orthogonal projections, centered, on a vertex, edges, face and normal to its vertex figure. The first and third correspond to the A2 and B2 Coxeter planes.
The cube can also be represented as a spherical tiling, and projected onto the plane via a stereographic projection. This projection is conformal, preserving angles but not areas or lengths. Straight lines on the sphere are projected as circular arcs on the plane.
For a cube centered at the origin, with edges parallel to the axes and with an edge length of 2, the Cartesian coordinates of the vertices are
while the interior consists of all points (x0, x1, x2) with −1 < xi < 1 for all i.
This configuration matrix represents the cube. The rows and columns correspond to vertices, edges, and faces. The diagonal numbers say how many of each element occur in the whole cube. The nondiagonal numbers say how many of the column's element occur in or at the row's element. For example, the 2 in the first column of the middle row indicates that there are 2 vertices in (i.e., at the extremes of) each edge; the 3 in the middle column of the first row indicates that 3 edges meet at each vertex.
[ 8 3 3 2 12 2 4 4 6 ] {\displaystyle {\begin{bmatrix}{\begin{matrix}8&3&3\\2&12&2\\4&4&6\end{matrix}}\end{bmatrix}}}
In analytic geometry, a cube's surface with center (x0, y0, z0) and edge length of 2a is the locus of all points (x, y, z) such that
A cube can also be considered the limiting case of a 3D superellipsoid as all three exponents approach infinity.
For a cube of edge length a {\displaystyle a} :
As the volume of a cube is the third power of its sides a × a × a {\displaystyle a\times a\times a} , third powers are called cubes, by analogy with squares and second powers.
A cube has the largest volume among cuboids (rectangular boxes) with a given surface area. Also, a cube has the largest volume among cuboids with the same total linear size (length+width+height).
For a cube whose circumscribing sphere has radius R, and for a given point in its 3-dimensional space with distances di from the cube's eight vertices, we have:
Doubling the cube, or the Delian problem, was the problem posed by ancient Greek mathematicians of using only a compass and straightedge to start with the length of the edge of a given cube and to construct the length of the edge of a cube with twice the volume of the original cube. They were unable to solve this problem, which in 1837 Pierre Wantzel proved it to be impossible because the cube root of 2 is not a constructible number.
The cube has three uniform colorings, named by the unique colors of the square faces around each vertex: 111, 112, 123.
The cube has four classes of symmetry, which can be represented by vertex-transitive coloring the faces. The highest octahedral symmetry Oh has all the faces the same color. The dihedral symmetry D4h comes from the cube being a solid, with all the six sides being different colors. The prismatic subsets D2d has the same coloring as the previous one and D2h has alternating colors for its sides for a total of three colors, paired by opposite sides. Each symmetry form has a different Wythoff symbol.
A cube has eleven nets: that is, there are eleven ways to flatten a hollow cube by cutting seven edges. To color the cube so that no two adjacent faces have the same color, one would need at least three colors.
The cube is the cell of the only regular tiling of three-dimensional Euclidean space. It is also unique among the Platonic solids in having faces with an even number of sides and, consequently, it is the only member of that group that is a zonohedron (every face has point symmetry).
The cube can be cut into six identical square pyramids. If these square pyramids are then attached to the faces of a second cube, a rhombic dodecahedron is obtained (with pairs of coplanar triangles combined into rhombic faces).
Cubes appear in Abrahamic religions. The Kaaba (Arabic for 'cube') in Mecca is one example. Cubes also appear in Judaism as tefillin, and the New Jerusalem is described in the New Testament as a cube.
The analogue of a cube in four-dimensional Euclidean space has a special name—a tesseract or hypercube. More properly, a hypercube (or n-dimensional cube or simply n-cube) is the analogue of the cube in n-dimensional Euclidean space and a tesseract is the order-4 hypercube. A hypercube is also called a measure polytope.
There are analogues of the cube in lower dimensions too: a point in dimension 0, a line segment in one dimension and a square in two dimensions.
The quotient of the cube by the antipodal map yields a projective polyhedron, the hemicube.
If the original cube has edge length 1, its dual polyhedron (an octahedron) has edge length 2 / 2 {\displaystyle \scriptstyle {\sqrt {2}}/2} .
The cube is a special case in various classes of general polyhedra:
The vertices of a cube can be grouped into two groups of four, each forming a regular tetrahedron; more generally this is referred to as a demicube. These two together form a regular compound, the stella octangula. The intersection of the two forms a regular octahedron. The symmetries of a regular tetrahedron correspond to those of a cube which map each tetrahedron to itself; the other symmetries of the cube map the two to each other.
One such regular tetrahedron has a volume of 1/3 of that of the cube. The remaining space consists of four equal irregular tetrahedra with a volume of 1/6 of that of the cube, each.
The rectified cube is the cuboctahedron. If smaller corners are cut off we get a polyhedron with six octagonal faces and eight triangular ones. In particular we can get regular octagons (truncated cube). The rhombicuboctahedron is obtained by cutting off both corners and edges to the correct amount.
A cube can be inscribed in a dodecahedron so that each vertex of the cube is a vertex of the dodecahedron and each edge is a diagonal of one of the dodecahedron's faces; taking all such cubes gives rise to the regular compound of five cubes.
If two opposite corners of a cube are truncated at the depth of the three vertices directly connected to them, an irregular octahedron is obtained. Eight of these irregular octahedra can be attached to the triangular faces of a regular octahedron to obtain the cuboctahedron.
The cube is topologically related to a series of spherical polyhedral and tilings with order-3 vertex figures.
The cuboctahedron is one of a family of uniform polyhedra related to the cube and regular octahedron.
The cube is topologically related as a part of sequence of regular tilings, extending into the hyperbolic plane: {4,p}, p=3,4,5...
With dihedral symmetry, Dih4, the cube is topologically related in a series of uniform polyhedral and tilings 4.2n.2n, extending into the hyperbolic plane:
All these figures have octahedral symmetry.
The cube is a part of a sequence of rhombic polyhedra and tilings with [n,3] Coxeter group symmetry. The cube can be seen as a rhombic hexahedron where the rhombi are squares.
The cube is a square prism:
As a trigonal trapezohedron, the cube is related to the hexagonal dihedral symmetry family.
It is an element of 9 of 28 convex uniform honeycombs:
It is also an element of five four-dimensional uniform polychora:
The skeleton of the cube (the vertices and edges) forms a graph with 8 vertices and 12 edges, called the cube graph. It is a special case of the hypercube graph. It is one of 5 Platonic graphs, each a skeleton of its Platonic solid.
An extension is the three dimensional k-ARY Hamming graph, which for k = 2 is the cube graph. Graphs of this sort occur in the theory of parallel processing in computers. | [
{
"paragraph_id": 0,
"text": "In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets, or sides, with three meeting at each vertex. Viewed from a corner, it is a hexagon and its net is usually depicted as a cross.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The cube is the only regular hexahedron and is one of the five Platonic solids. It has 6 faces, 12 edges, and 8 vertices.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The cube is also a square parallelepiped, an equilateral cuboid, a right rhombohedron, and a 3-zonohedron. It is a regular square prism in three orientations, and a trigonal trapezohedron in four orientations.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The cube is dual to the octahedron. It has cubical or octahedral symmetry, and is the only convex polyhedron whose faces are all squares. Its generalization for higher-dimensional spaces is called a hypercube.",
"title": ""
},
{
"paragraph_id": 4,
"text": "The cube has four special orthogonal projections, centered, on a vertex, edges, face and normal to its vertex figure. The first and third correspond to the A2 and B2 Coxeter planes.",
"title": "Orthogonal projections"
},
{
"paragraph_id": 5,
"text": "The cube can also be represented as a spherical tiling, and projected onto the plane via a stereographic projection. This projection is conformal, preserving angles but not areas or lengths. Straight lines on the sphere are projected as circular arcs on the plane.",
"title": "Spherical tiling"
},
{
"paragraph_id": 6,
"text": "For a cube centered at the origin, with edges parallel to the axes and with an edge length of 2, the Cartesian coordinates of the vertices are",
"title": "Cartesian coordinates"
},
{
"paragraph_id": 7,
"text": "while the interior consists of all points (x0, x1, x2) with −1 < xi < 1 for all i.",
"title": "Cartesian coordinates"
},
{
"paragraph_id": 8,
"text": "This configuration matrix represents the cube. The rows and columns correspond to vertices, edges, and faces. The diagonal numbers say how many of each element occur in the whole cube. The nondiagonal numbers say how many of the column's element occur in or at the row's element. For example, the 2 in the first column of the middle row indicates that there are 2 vertices in (i.e., at the extremes of) each edge; the 3 in the middle column of the first row indicates that 3 edges meet at each vertex.",
"title": "Cartesian coordinates"
},
{
"paragraph_id": 9,
"text": "[ 8 3 3 2 12 2 4 4 6 ] {\\displaystyle {\\begin{bmatrix}{\\begin{matrix}8&3&3\\\\2&12&2\\\\4&4&6\\end{matrix}}\\end{bmatrix}}}",
"title": "Cartesian coordinates"
},
{
"paragraph_id": 10,
"text": "In analytic geometry, a cube's surface with center (x0, y0, z0) and edge length of 2a is the locus of all points (x, y, z) such that",
"title": "Equation in three dimensional space"
},
{
"paragraph_id": 11,
"text": "A cube can also be considered the limiting case of a 3D superellipsoid as all three exponents approach infinity.",
"title": "Equation in three dimensional space"
},
{
"paragraph_id": 12,
"text": "For a cube of edge length a {\\displaystyle a} :",
"title": "Formulas"
},
{
"paragraph_id": 13,
"text": "As the volume of a cube is the third power of its sides a × a × a {\\displaystyle a\\times a\\times a} , third powers are called cubes, by analogy with squares and second powers.",
"title": "Formulas"
},
{
"paragraph_id": 14,
"text": "A cube has the largest volume among cuboids (rectangular boxes) with a given surface area. Also, a cube has the largest volume among cuboids with the same total linear size (length+width+height).",
"title": "Formulas"
},
{
"paragraph_id": 15,
"text": "For a cube whose circumscribing sphere has radius R, and for a given point in its 3-dimensional space with distances di from the cube's eight vertices, we have:",
"title": "Formulas"
},
{
"paragraph_id": 16,
"text": "Doubling the cube, or the Delian problem, was the problem posed by ancient Greek mathematicians of using only a compass and straightedge to start with the length of the edge of a given cube and to construct the length of the edge of a cube with twice the volume of the original cube. They were unable to solve this problem, which in 1837 Pierre Wantzel proved it to be impossible because the cube root of 2 is not a constructible number.",
"title": "Doubling the cube"
},
{
"paragraph_id": 17,
"text": "The cube has three uniform colorings, named by the unique colors of the square faces around each vertex: 111, 112, 123.",
"title": "Uniform colorings and symmetry"
},
{
"paragraph_id": 18,
"text": "The cube has four classes of symmetry, which can be represented by vertex-transitive coloring the faces. The highest octahedral symmetry Oh has all the faces the same color. The dihedral symmetry D4h comes from the cube being a solid, with all the six sides being different colors. The prismatic subsets D2d has the same coloring as the previous one and D2h has alternating colors for its sides for a total of three colors, paired by opposite sides. Each symmetry form has a different Wythoff symbol.",
"title": "Uniform colorings and symmetry"
},
{
"paragraph_id": 19,
"text": "A cube has eleven nets: that is, there are eleven ways to flatten a hollow cube by cutting seven edges. To color the cube so that no two adjacent faces have the same color, one would need at least three colors.",
"title": "Geometric relations"
},
{
"paragraph_id": 20,
"text": "The cube is the cell of the only regular tiling of three-dimensional Euclidean space. It is also unique among the Platonic solids in having faces with an even number of sides and, consequently, it is the only member of that group that is a zonohedron (every face has point symmetry).",
"title": "Geometric relations"
},
{
"paragraph_id": 21,
"text": "The cube can be cut into six identical square pyramids. If these square pyramids are then attached to the faces of a second cube, a rhombic dodecahedron is obtained (with pairs of coplanar triangles combined into rhombic faces).",
"title": "Geometric relations"
},
{
"paragraph_id": 22,
"text": "Cubes appear in Abrahamic religions. The Kaaba (Arabic for 'cube') in Mecca is one example. Cubes also appear in Judaism as tefillin, and the New Jerusalem is described in the New Testament as a cube.",
"title": "In theology"
},
{
"paragraph_id": 23,
"text": "The analogue of a cube in four-dimensional Euclidean space has a special name—a tesseract or hypercube. More properly, a hypercube (or n-dimensional cube or simply n-cube) is the analogue of the cube in n-dimensional Euclidean space and a tesseract is the order-4 hypercube. A hypercube is also called a measure polytope.",
"title": "Other dimensions"
},
{
"paragraph_id": 24,
"text": "There are analogues of the cube in lower dimensions too: a point in dimension 0, a line segment in one dimension and a square in two dimensions.",
"title": "Other dimensions"
},
{
"paragraph_id": 25,
"text": "The quotient of the cube by the antipodal map yields a projective polyhedron, the hemicube.",
"title": "Related polyhedra"
},
{
"paragraph_id": 26,
"text": "If the original cube has edge length 1, its dual polyhedron (an octahedron) has edge length 2 / 2 {\\displaystyle \\scriptstyle {\\sqrt {2}}/2} .",
"title": "Related polyhedra"
},
{
"paragraph_id": 27,
"text": "The cube is a special case in various classes of general polyhedra:",
"title": "Related polyhedra"
},
{
"paragraph_id": 28,
"text": "The vertices of a cube can be grouped into two groups of four, each forming a regular tetrahedron; more generally this is referred to as a demicube. These two together form a regular compound, the stella octangula. The intersection of the two forms a regular octahedron. The symmetries of a regular tetrahedron correspond to those of a cube which map each tetrahedron to itself; the other symmetries of the cube map the two to each other.",
"title": "Related polyhedra"
},
{
"paragraph_id": 29,
"text": "One such regular tetrahedron has a volume of 1/3 of that of the cube. The remaining space consists of four equal irregular tetrahedra with a volume of 1/6 of that of the cube, each.",
"title": "Related polyhedra"
},
{
"paragraph_id": 30,
"text": "The rectified cube is the cuboctahedron. If smaller corners are cut off we get a polyhedron with six octagonal faces and eight triangular ones. In particular we can get regular octagons (truncated cube). The rhombicuboctahedron is obtained by cutting off both corners and edges to the correct amount.",
"title": "Related polyhedra"
},
{
"paragraph_id": 31,
"text": "A cube can be inscribed in a dodecahedron so that each vertex of the cube is a vertex of the dodecahedron and each edge is a diagonal of one of the dodecahedron's faces; taking all such cubes gives rise to the regular compound of five cubes.",
"title": "Related polyhedra"
},
{
"paragraph_id": 32,
"text": "If two opposite corners of a cube are truncated at the depth of the three vertices directly connected to them, an irregular octahedron is obtained. Eight of these irregular octahedra can be attached to the triangular faces of a regular octahedron to obtain the cuboctahedron.",
"title": "Related polyhedra"
},
{
"paragraph_id": 33,
"text": "The cube is topologically related to a series of spherical polyhedral and tilings with order-3 vertex figures.",
"title": "Related polyhedra"
},
{
"paragraph_id": 34,
"text": "The cuboctahedron is one of a family of uniform polyhedra related to the cube and regular octahedron.",
"title": "Related polyhedra"
},
{
"paragraph_id": 35,
"text": "The cube is topologically related as a part of sequence of regular tilings, extending into the hyperbolic plane: {4,p}, p=3,4,5...",
"title": "Related polyhedra"
},
{
"paragraph_id": 36,
"text": "With dihedral symmetry, Dih4, the cube is topologically related in a series of uniform polyhedral and tilings 4.2n.2n, extending into the hyperbolic plane:",
"title": "Related polyhedra"
},
{
"paragraph_id": 37,
"text": "All these figures have octahedral symmetry.",
"title": "Related polyhedra"
},
{
"paragraph_id": 38,
"text": "The cube is a part of a sequence of rhombic polyhedra and tilings with [n,3] Coxeter group symmetry. The cube can be seen as a rhombic hexahedron where the rhombi are squares.",
"title": "Related polyhedra"
},
{
"paragraph_id": 39,
"text": "The cube is a square prism:",
"title": "Related polyhedra"
},
{
"paragraph_id": 40,
"text": "As a trigonal trapezohedron, the cube is related to the hexagonal dihedral symmetry family.",
"title": "Related polyhedra"
},
{
"paragraph_id": 41,
"text": "It is an element of 9 of 28 convex uniform honeycombs:",
"title": "Related polyhedra"
},
{
"paragraph_id": 42,
"text": "It is also an element of five four-dimensional uniform polychora:",
"title": "Related polyhedra"
},
{
"paragraph_id": 43,
"text": "The skeleton of the cube (the vertices and edges) forms a graph with 8 vertices and 12 edges, called the cube graph. It is a special case of the hypercube graph. It is one of 5 Platonic graphs, each a skeleton of its Platonic solid.",
"title": "Cubical graph"
},
{
"paragraph_id": 44,
"text": "An extension is the three dimensional k-ARY Hamming graph, which for k = 2 is the cube graph. Graphs of this sort occur in the theory of parallel processing in computers.",
"title": "Cubical graph"
}
] | In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets, or sides, with three meeting at each vertex. Viewed from a corner, it is a hexagon and its net is usually depicted as a cross. The cube is the only regular hexahedron and is one of the five Platonic solids. It has 6 faces, 12 edges, and 8 vertices. The cube is also a square parallelepiped, an equilateral cuboid, a right rhombohedron, and a 3-zonohedron. It is a regular square prism in three orientations, and a trigonal trapezohedron in four orientations. The cube is dual to the octahedron. It has cubical or octahedral symmetry, and is the only convex polyhedron whose faces are all squares. Its generalization for higher-dimensional spaces is called a hypercube. | 2001-09-07T17:57:17Z | 2023-12-20T14:55:32Z | [
"Template:Reg polyhedra db",
"Template:Order-3 tiling table",
"Template:Reflist",
"Template:Mathworld",
"Template:Other uses",
"Template:CDD",
"Template:Octahedral truncations",
"Template:Convex polyhedron navigator",
"Template:Sfn",
"Template:UniformPrisms",
"Template:Hexagonal dihedral truncations",
"Template:Polytopes",
"Template:Sfrac",
"Template:Notelist",
"Template:Infobox graph",
"Template:Authority control",
"Template:Clear",
"Template:Efn",
"Template:Regular square tiling table",
"Template:Dual quasiregular3 table",
"Template:Cite journal",
"Template:Mergefrom",
"Template:Cite web",
"Template:Truncated figure3 table",
"Template:Redirect-distinguish",
"Template:Webarchive",
"Template:Cite book",
"Template:Short description"
] | https://en.wikipedia.org/wiki/Cube |
6,286 | Commuter rail | Commuter rail, or suburban rail, is a passenger rail transport service that primarily operates within a metropolitan area, connecting commuters to a central city from adjacent suburbs or commuter towns. Commuter rail systems are considered heavy rail, using electrified or diesel trains. Distance charges or zone pricing may be used.
The term can refer to systems with a wide variety of different features and service frequencies, but is often used in contrast to rapid transit or light rail.
Some services share similarities with both commuter rail and high-frequency rapid transit, examples being the German S-Bahn in some cities, the Réseau Express Régional (RER) in Paris, the S Lines in Milan, many Japanese commuter systems, the East Rail line in Hong Kong and some Australasian suburban networks, such as Sydney Trains. Some services, like British commuter rail, share tracks with other passenger services and freight.
In North America, commuter rail sometimes refers only to systems that primarily operate during peak periods and offer little to no service for the rest of the day, with regional rail being used to refer to systems that offer all-day service.
Most commuter (or suburban) trains are built to main line rail standards, differing from light rail or rapid transit (metro rail) systems by:
Compared to rapid transit (or metro rail), commuter/suburban rail often has lower frequency, following a schedule rather than fixed intervals, and fewer stations spaced further apart. They primarily serve lower density suburban areas (non inner-city), generally only having one or two stops in a city's central business district, and often share right-of-way with intercity or freight trains. Some services operate only during peak hours and others uses fewer departures during off peak hours and weekends. Average speeds are high, often 50 km/h (30 mph) or higher. These higher speeds better serve the longer distances involved. Some services include express services which skip some stations in order to run faster and separate longer distance riders from short-distance ones.
The general range of commuter trains' travel distance varies between 15 and 200 km (10 and 125 miles), but longer distances can be covered when the trains run between two or several cities (e.g. S-Bahn in the Ruhr area of Germany). Distances between stations may vary, but are usually much longer than those of urban rail systems. In city centers the train either has a terminal station or passes through the city centre with notably fewer station stops than those of urban rail systems. Toilets are often available on-board trains and in stations.
Their ability to coexist with freight or intercity services in the same right-of-way can drastically reduce system construction costs. However, frequently they are built with dedicated tracks within that right-of-way to prevent delays, especially where service densities have converged in the inner parts of the network.
Most such trains run on the local standard gauge track. Some systems may run on a narrower or broader gauge. Examples of narrow gauge systems are found in Japan, Indonesia, Malaysia, Thailand, Taiwan, Switzerland, in the Brisbane (Queensland Rail's City network) and Perth (Transperth) systems in Australia, in some systems in Sweden, and on the Genoa-Casella line in Italy. Some countries and regions, including Finland, India, Pakistan, Russia, Brazil and Sri Lanka, as well as San Francisco (BART) in the US and Melbourne and Adelaide in Australia, use broad gauge track.
Metro rail and rapid transit usually cover smaller inner-urban areas within 12 to 20 km (7 to 12 mi) of city centers, with shorter stop spacing, use rolling stocks with larger standing spaces, lower top speed and higher acceleration, designed for short-distance travel. They also run more frequently, to a headway rather than a published timetable and use dedicated tracks (underground or elevated), whereas commuter rail often shares tracks, technology and the legal framework within mainline railway systems, and uses rolling stocks with more seating and higher speed for comfort on longer city-suburban journeys.
However, the classification as a metro or rapid rail can be difficult as both may typically cover a metropolitan area exclusively, run on separate tracks in the centre, and often feature purpose-built rolling stock. The fact that the terminology is not standardised across countries (even across English-speaking countries) further complicates matters. This distinction is most easily made when there are two (or more) systems such as New York's subway and the LIRR and Metro-North Railroad, Paris' Métro and RER along with Transilien, Washington D.C.'s Metro along with its MARC and VRE, London's tube lines of the Underground and the Overground, Elizabeth line, Thameslink along with other commuter rail operators, Madrid's Metro and Cercanías, Barcelona's Metro and Rodalies, and Tokyo's subway and the JR lines along with various privately owned and operated commuter rail systems.
Regional rail usually provides rail services between towns and cities, rather than purely linking major population hubs in the way inter-city rail does. Regional rail operates outside major cities. Unlike Inter-city, it stops at most or all stations between cities. It provides a service between smaller communities along the line that are often byproducts of ribbon developments, and also connects with long-distance services at interchange stations located at junctions, terminals, or larger towns along the line. Alternative names are "local train" or "stopping train". Examples include the former BR's Regional Railways, France's TER (Transport express régional), Germany's Regionalexpress and Regionalbahn, and South Korea's Tonggeun services.
In some European countries, the distinction between commuter trains and long-distance/intercity trains is subtle, due to the relatively short distances involved. For example, so-called "intercity" trains in Belgium and the Netherlands carry many commuters, while their equipment, range, and speeds are similar to those of commuter trains in some larger countries.
The United Kingdom has a privatised rail system, with different routes and services covered by different private operators. The distinction between commuter and intercity rail is not as clear as it was before privatisation (when InterCity existed as a brand of its own), but usually it is still possible to tell them apart. Some operators, for example Thameslink, focus solely on commuter services. Others, such as Avanti West Coast and LNER, run solely intercity services. Others still, such as GWR and EMR, run a mixture of commuter, regional and intercity services. Some of these operators use different branding for different types of service (for example EMR brands its trains as either "InterCity", "Connect" for London commuter services, and "Regional") but even for those operators that do not, the type of train, amenities offered, and stopping pattern, usually tell the services apart.
Russian commuter trains, on the other hand, frequently cover areas larger than Belgium itself, although these are still short distances by Russian standards. They have a different ticketing system from long-distance trains, and in major cities they often operate from a separate section of the train station.
Some consider "inter-city" service to be that which operates as an express service between two main city stations, bypassing intermediate stations. However, this term is used in Australia (Sydney for example) to describe the regional trains operating beyond the boundaries of the suburban services, even though some of these "inter-city" services stop all stations similar to German regional services. In this regard, the German service delineations and naming conventions are clearer and better used for academic purposes.
Sometimes high-speed rail can serve daily use of commuters. The Japanese Shinkansen high speed rail system is heavily used by commuters in the Greater Tokyo Area, who commute between 100 and 200 km (62 and 124 mi) by Shinkansen. To meet the demand of commuters, JR sells commuter discount passes. Before 2021, they operated 16-car bilevel E4 Series Shinkansen trains at rush hour, providing a capacity of 1,600 seats. Several lines in China, such as the Beijing–Tianjin Intercity Railway and the Shanghai–Nanjing High-Speed Railway, serve a similar role with many more under construction or planned.
In South Korea, some sections of the high-speed rail network are also heavily used by commuters, such as the section between Gwangmyeong Station and Seoul Station on the KTX network (Gyeongbu HSR Line), or the section between Dongtan Station and Suseo station on the SRT Line.
The high-speed services linking Zürich, Bern and Basel in Switzerland (200 km/h (120 mph)) have brought the Central Business Districts (CBDs) of these three cities within 1 hour of each other. This has resulted in unexpectedly high demand for new commuter trips between the three cities and a corresponding increase in suburban rail passengers accessing the high-speed services at the main city-centre stations (Hauptbahnhof). The Regional-Express commuter service between Munich and Nuremberg in Germany runs at 200 km/h (120 mph) on the 300 km/h (186 mph) Nuremberg–Ingolstadt high-speed railway.
The regional trains Stockholm–Uppsala, Stockholm–Västerås, Stockholm–Eskilstuna and Gothenburg–Trollhättan in Sweden reach 200 km/h (120 mph) and have many daily commuters.
In Great Britain, the HS1 domestic services between London and Ashford runs at a top speed of 225 km/h, and in peak hours the trains can be full with commuters standing.
The Athens Suburban Railway in Greece consists of five lines, 4 of which are electrified. The Kiato–Piraeus line and the Aigio–Airport lines reach speeds of up to 180 km/h (112 mph). The Athens–Chalcis line is also expected to attain speeds of up to 200 km/h (124 mph) upon upgrading of the SKA–Oinoi railway sector. These lines also have many daily commuters, with the number expected to rise even higher upon full completion of the Acharnes Railway Center.
Eskişehir-Ankara and Konya-Ankara high speed train routes serve as high speed commuter trains in Turkey.
Commuter/suburban trains are usually optimized for maximum passenger volume, in most cases without sacrificing too much comfort and luggage space, though they seldom have all the amenities of long-distance trains. Cars may be single- or double-level, and aim to provide seating for all. Compared to intercity trains, they have less space, fewer amenities and limited baggage areas.
Commuter rail trains are usually composed of multiple units, which are self-propelled, bidirectional, articulated passenger rail cars with driving motors on each (or every other) bogie. Depending on local circumstances and tradition they may be powered either by diesel engines located below the passenger compartment (diesel multiple units) or by electricity picked up from third rails or overhead lines (electric multiple units). Multiple units are almost invariably equipped with control cabs at both ends, which is why such units are so frequently used to provide commuter services, due to the associated short turn-around time.
Locomotive hauled services are used in some countries or locations. This is often a case of asset sweating, by using a single large combined fleet for intercity and regional services. Loco hauled services are usually run in push-pull formation, that is, the train can run with the locomotive at the "front" or "rear" of the train (pushing or pulling). Trains are often equipped with a control cab at the other end of the train from the locomotive, allowing the train operator to operate the train from either end. The motive power for locomotive-hauled commuter trains may be either electric or diesel-electric, although some countries, such as Germany and some of the former Soviet-bloc countries, also use diesel-hydraulic locomotives.
In the US and some other countries, a three-and-two seat plan is used. Middle seats on these trains are often less popular because passengers feel crowded and uncomfortable.
In Japan, South Korea and Indonesia, longitudinal (sideways window-lining) seating is widely used in many commuter rail trains to increase capacity in rush hours. Carriages are usually not organized to increase seating capacity (although in some trains at least one carriage would feature more doors to facilitate easier boarding and alighting and bench seats so that they can be folded up during rush hour to provide more standing room) even in the case of commuting longer than 50 km and commuters in the Greater Tokyo Area, Seoul metropolitan area, and Jabodetabek area have to stand in the train for more than an hour.
Currently there are not many examples of commuter rail in Africa. Metrorail operates in the major cities of South Africa, and there are some commuter rail services in Algeria, Botswana, Kenya, Morocco, Egypt and Tunisia. In Algeria, SNTF operates commuter rail lines between the capital Algiers and its southern and eastern suburbs. They also serve to connect Algiers' main universities to each other. The Dar es Salaam commuter rail offers intracity services in Dar es Salaam, Tanzania. In Botswana, the (Botswana Railways) "BR Express" has a commuter train between Lobatse and Gaborone.
In Japan, commuter rail systems have extensive network and frequent service and are heavily used. In many cases, Japanese commuter rail is operationally more like a typical metro system (frequent trains, an emphasis on standing passengers, short station spacings) than it is like commuter rail in other countries. Japanese commuter rail commonly interline with city center subway lines, with commuter rail trains continuing into the subway network, and then out onto different commuter rail systems on the other side of the city. Many Japanese commuter systems operate various stopping patterns to reduce the travel time to distant locations, often using station passing loops instead of dedicated express tracks. It is notable that the larger Japanese commuter rail systems are owned and operated by for-profit private railway companies, without public subsidy.
East Japan Railway Company operates a large suburban train network in Tokyo with various lines connecting the suburban areas to the city center. While the Yamanote Line, Keihin Tohoku Line, Chūō–Sōbu Line services arguably are more akin to rapid transit with frequent stops, simple stopping patterns (relative to other JR East lines) no branching services and largely serving the inner suburbs; other services along the Chūō Rapid Line, Sōbu Rapid Line/Yokosuka Line, Ueno–Tokyo Line, Shōnan–Shinjuku Line etc. are mid-distance services from suburban lines in the outer reaches of Greater Tokyo through operating into these lines to form a high frequency corridor though central Tokyo.
Other commuter rail routes in Japan include:
Commuter rail systems have been inaugurated in several cities in China such as Beijing, Shanghai, Zhengzhou, Wuhan, Changsha and the Pearl River Delta. With plans for large systems in northeastern Zhejiang, Jingjinji, and Yangtze River Delta areas. The level of service varies considerably from line to line ranging high to near high speeds. More developed and established lines such as the Guangshen Railway have more frequent metro-like service.
The two MTR lines which are owned and formerly operated by the Kowloon-Canton Railway Corporation (East Rail line and Tuen Ma line which is integrated from the former West Rail line and Ma On Shan line in 2021), then the "KCR"), and MTR's own Tung Chung line connect the new towns in New Territories and the city centre Kowloon together with frequent intervals, and some New Territories-bound trains terminate at intermediate stations, providing more frequent services in Kowloon and the towns closer to Kowloon. They use rolling stocks with a faster maximum speed and have longer stop spacing compard to other lines which only run in the inner urban area, but in order to maximise capacity and throughput, these rolling stocks have longitudinal seatings, 5 pairs of doors in each carriage with large standing spaces like the urban lines, and run as frequent as well. Most of the sections of these four lines are overground and some sections of the East Rail Line share tracks with intercity trains to mainland China. The three KCR lines are integrated into the MTR network since 2008 and most passengers do not need to exit and re-enter the system through separate fare gates and purchase separate tickets to transfer between such lines and the rest of the network (the exceptions are between the Tuen Ma line's East Tsim Sha Tsui station and the Tsuen Wan line's Tsim Sha Tsui station.
In Taiwan, the Western line in the Taipei-Taoyuan Metropolitan Area, Taichung Metropolitan Area and Tainan-Kaohsiung Metropolitan Area as well as the Neiwan-Liujia line in the Hsinchu Area are considered commuter rail.
In South Korea, the Seoul Metropolitan Subway includes a total of 22 lines, and some of its lines are suburban lines. This is especially the case for lines operated by Korail, such as the Gyeongui-Jungang Line, the Gyeongchun Line, the Suin-Bundang Line, or the Gyeonggang Line. Even some lines not operated by Korail, such as the AREX Line, the Seohae Line or the Shinbundang Line mostly function as commuter rail. Lastly, even for the "numbered lines" (1–9) of the Seoul Metropolitan Subway which mostly travel in the dense parts of Seoul, some track sections extend far outside of the city, and operate large sections at ground level, such as on the Line 1, Line 3 and Line 4. In Busan, the Donghae Line, while part of the Busan Metro system, mostly functions as a commuter rail line.
In Indonesia, the KRL Commuterline is the largest commuter rail system in the country, serving the Greater Jakarta. It connects the Jakarta city center with surrounding cities and sub-urbans in Banten and West Java provinces, including Depok, Bogor, Tangerang, Serpong, Rangkasbitung, Bekasi and Cikarang. In July 2015, KA Commuter Jabodetabek served more than 850,000 passengers per day, which is almost triple of the 2011 figures, but still less than 3.5% of all Jabodetabek commutes. Other commuter rail systems in Indonesia include the Metro Surabaya Commuter Line, Prambanan Express, KRL Commuterline Yogyakarta–Solo, Kedung Sepur, and the Greater Bandung Commuter.
In the Philippines, the Philippine National Railways has two commuter rail systems currently operational; the PNR Metro Commuter Line in the Greater Manila Area and the PNR Bicol Commuter in the Bicol Region. A new commuter rail line in Metro Manila, the North–South Commuter Railway, is currently under construction. Its North section is set to be partially opened by 2021.
In Malaysia, there are two commuter services operated by Keretapi Tanah Melayu. They are the KTM Komuter that serves Kuala Lumpur and the surrounding Klang Valley area, and the KTM Komuter Northern Sector that serves Greater Penang, Perak, Kedah and Perlis in the northern region of Peninsular Malaysia.
In Thailand, the Greater Bangkok Commuter rail and the Airport Rail Link serve the Bangkok Metropolitan Region. The SRT Red Lines, a new commuter line in Bangkok, started construction in 2009. It opened in 2021.
Another commuter rail system in Southeast Asia is the Yangon Circular Railway in Myanmar.
In India, commuter rail systems are present in major cities and form an important part of people's daily lives. Mumbai Suburban Railway, the oldest suburban rail system in Asia, carries more than 7.24 million commuters on a daily basis which constitutes more than half of the total daily passenger capacity of the Indian Railways itself. Kolkata Suburban Railway, one of the largest suburban railway networks in the world, consists of more than 450 stations and carries more than 3.5 million commuters per day. The Chennai Suburban Railway along with the Chennai MRTS, also covers over 300 stations and carries more than 2.5 million people daily to different areas in Chennai and its surroundings. Other commuter railways in India include the Hyderabad MMTS, Delhi Suburban Railway, Pune Suburban Railway and Lucknow-Kanpur Suburban Railway.
In 2020, Government of India approved Bengaluru Suburban Railway to connect Bengaluru and its suburbs. It will be unique and first of its kind in India as it will have metro like facilities and rolling stock.
In Bangladesh, there is one suburban rail called the Chittagong Circular Railway. Another suburban railway called the Dhaka Circular Railway is currently proposed.
Karachi in Pakistan has a circular railway since 1969.
In Iran, SYSTRA proposed 4 express lines similar to RER suburban lines in Paris. Tehran Metro is going to construct express lines. For instance, the Rahyab Behineh, a consultant for Tehran Metro, is studying Tehran Express Line 2. Tehran Metro currently has a commuter line, which is Line 5 between Tehran and Karaj. Isfahan has two lines to its suburbs Baharestan and Fuladshahr under construction, and a third line to Shahinshahr is planned.
In Turkey; Başkentray, İZBAN, Marmaray and Gaziray are well-known examples.
Major metropolitan areas in most European countries are usually served by extensive commuter/suburban rail systems. Well-known examples include BG Voz in Belgrade (Serbia), S-Bahn in Germany, Austria and German-speaking areas of Switzerland, Proastiakos in Greece, RER in France and Belgium, Servizio ferroviario suburbano in Italy, Cercanías and Rodalies (Catalonia) in Spain, CP Urban Services in Portugal, Esko in Prague and Ostrava (Czech Republic), HÉV in Budapest (Hungary) and DART in Dublin (Ireland).
London has multiple commuter rail routes:
The Merseyrail network in Liverpool consists of two commuter rail routes powered by third rail, both of which branch out at one end. At the other, the Northern Line continues out of the city centre to a mainline rail interchange, while the Wirral Line has a city-centre loop.
Birmingham has four suburban routes, one of which is operated with diesel trains.
The Tyneside Electrics system in Newcastle existed from 1904 to 1967 using DC third rail. British Rail did not have the budget to maintain the ageing electrification system. The Riverside Branch was closed, while the remaining lines were de-electrified. 13 years later, they were re-electrified using DC overhead wires, and now form the Tyne & Wear Metro Yellow Line.
Many of the rail services around Glasgow are branded as Strathclyde Partnership for Transport. The network includes most electrified Scottish rail routes.
The Metro run eleven services which feed into Leeds, connecting the city with commuter areas and neighbouring urban centres in the West Yorkshire Connurbation.
MetroWest is a proposed network in Bristol, northern Somerset & southern Gloucestershire. The four-tracking of the line between Bristol Temple Meads and Bristol Parkway stations will enable local rail services to be separated from long-distance trains.
The Réseau express régional d'Île-de-France (RER) is a commuter rail network in the agglomeration of Paris. In the centre the RER has high frequency underground corridors where several suburban branches feed similar to a rapid transit system.
Commuter rail systems in Germany are called S-Bahn. While in some major cities S-Bahn services run on separate lines exclusively other systems use the existing regional rail tracks.
Randstadspoor is a network of Sprinter train services in and around the city of Utrecht in the Netherlands. For the realisation of this network, new stations were opened. Separate tracks have been built for these trains, so they can call frequently without disturbing high-frequent Intercity services parallel to these routes. Similar systems are planned for The Hague and Rotterdam.
In Sweden, electrified commuter rail systems known as Pendeltåg are present in the cities of Stockholm and Gothenburg. The Stockholm commuter rail system, which began in 1968, shares railway tracks with inter-city trains and freight trains, but for the most part runs on its own dedicated tracks. It is primarily used to transport passengers from nearby towns and other suburban areas into the city centre, not for transportation inside the city centre. The Gothenburg commuter rail system, which began in 1960, is similar to the Stockholm system, but does fully share tracks with long-distance trains.
In Norway, the Oslo commuter rail system mostly shares tracks with more long-distance trains, but also runs on some local railways without other traffic. Services converge on a primary main line between Asker and Lillestrøm. Oslo has the largest commuter rail system in the Nordic countries in terms of line lengths and number of stations. But some lines have travel times (over an hour from Oslo) and frequencies (once per hour) which are more like regional trains. Also Bergen, Stavanger and Trondheim have commuter rail systems. These have only one or two lines each and they share tracks with other trains.
In Finland, the Helsinki commuter rail network runs on dedicated tracks from Helsinki Central railway station to Leppävaara and Kerava. The Ring Rail Line serves Helsinki Airport and northern suburbs of Vantaa and is exclusively used by the commuter rail network. On 15 December 2019, the Tampere region got its own commuter rail service, with trains running from Tampere to Nokia, Lempäälä and Orivesi.
In Spain, Cercanías networks exist in Madrid, Sevilla, Murcia/Alicante, San Sebastián, Cádiz, Valencia, Asturias, Santander, Zaragoza, Bilbao and Málaga. All these systems include underground sections in the city centre. There is also a network of narrow-gauge commuter systems in North Spain and Murcia.
Cercanías Madrid is one of the most important train services in the country, more than 900,000 passengers move in the system. It has underground stations in Madrid like Recoletos, Sol or Nuevos Ministerios and in the metropolitan area in cities like Parla or Getafe.
In the autonomous community of Catalonia, and unlike the rest of Spain, the commuter service is not managed by Renfe Operadora. Since 2010, the Government of Catalonia has managed all the regular commuter services with the "transfer of Rodalies". There are two companies that manage the Catalan commuter network:
The Government of Catalonia will assume full control of the current R12 regional line in 2024 and it will be owned by the FGC. It will eliminate the current line and replace it with the new commuter lines RL3 and RL4, towards Cervera and Manresa from Lleida respectively.
In Italy there are several commuter rail networks:
In Poland, commuter rail systems exist in Tricity, Warsaw, Kraków (SKA) and Katowice (SKR). There is also a similar system planned in Wrocław and Szczecin. The terms used are "Szybka Kolej Miejska" (fast urban rail) and "kolej aglomeracyjna" (agglomeration rail). These systems are:
The Proastiakos (Greek: Προαστιακός; "suburban") is Greece's suburban railway (commuter rail) services, which are run by TrainOSE, on infrastructure owned by the Hellenic Railways Organisation (OSE). There are three Proastiakos networks, servicing the country's three largest cities: Athens, Thessaloniki and Patras. In particular, the Athenian network is undergoing modifications to completely separate it from mainline traffic, by re-routing the tracks via a tunnel underneath the city center. A similar project is planned for the Patras network, whereas a new line is due to be constructed for the Thessalonian network.
In Romania, the first commuter trains were introduced in December 2019. They operate between Bucharest and Funduea or Buftea.
BG Voz is an urban rail system that serves Belgrade. It currently has only two routes, with plans for further expansion. Between early 1990s and mid-2010s, there was another system, known as Beovoz, that was used to provide mass-transit service within the Belgrade metropolitan area, as well as to nearby towns, similarly to RER in Paris. Beovoz had more lines and far more stops than the current system. However, it was abandoned in favor of more accurate BG Voz, mostly due to inefficiency. While current services rely mostly on the existing infrastructure, any further development means furthering capacities (railways expansion and new trains). Plans for further extension of system include another two lines, one of which should reach Belgrade Nikola Tesla Airport.
In Russia, Ukraine and some other countries of the former Soviet Union, electrical multiple unit passenger suburban trains called Elektrichka are widespread. The first such system in Russia is the Oranienbaum Electric Line in St. Petersburg. In Moscow the Beskudnikovskaya railway branch existed between the 1940s and 1980s. The trains that shuttled along it did not go to the main lines, so it was a city transport. Today there are the Moscow Central Circle and the Moscow Central Diameters.
In Turkey, Marmaray line stations from Sirkeci to Halkalı are located at the European side. Overground section between Kazlıçeşme and Sirkeci, stations such as Cankurtaran, are closed since 2013.
In the United States, Canada, Costa Rica, El Salvador and Mexico regional passenger rail services are provided by governmental or quasi-governmental agencies, with the busiest and most expansive rail networks located in the Northeastern US, California, and Eastern Canada. Most North American commuter railways utilize diesel locomotive propulsion, with the exception of services in New York City, Philadelphia, Chicago, Denver, and Mexico City; New York's commuter rail lines use a combination of third rail and overhead wire power generation, while Chicago only has two out of twelve services that are electrified. Many newer and proposed systems in Canada and the United States are often are geared to serving peak-hour commutes as opposed to the all-day systems of Europe, East Asia, and Australia.
Eight commuter rail systems in the United States carried over ten million trips in 2018, those being in descending order:
Other commuter rail systems in the United States (not in ridership order) are:
Examples include an 899 km (559 mi) commuter system in the Buenos Aires metropolitan area, the 225 km (140 mi) long Supervia in Rio de Janeiro, the Metrotrén in Santiago, Chile, and the Valparaíso Metro in Valparaíso, Chile.
Another example is Companhia Paulista de Trens Metropolitanos (CPTM) in Greater São Paulo, Brazil. CPTM has 94 stations with seven lines, numbered starting on 7 (the lines 1 to 6 and the line 15 belong to the São Paulo Metro), with a total length of 273 kilometres (170 mi). Trains operates at high frequencies on tracks used exclusively for commuter traffic. In Rio de Janeiro SuperVia provides electrified commuter rail services.
The five major cities in Australia have suburban railway systems in their metropolitan areas. These networks have frequent services, with frequencies varying from every 10 to every 30 minutes on most suburban lines, and up to 3–5 minutes in peak on bundled underground lines in the city centres of Sydney, Brisbane, Perth and Melbourne. The networks in each state developed from mainline railways and have never been completely operationally separate from long distance and freight traffic, unlike metro systems. The suburban networks are almost completely electrified.
The main suburban rail networks in Australia are:
New Zealand has two frequent suburban rail services comparable to those in Australia: the Auckland rail network is operated by Auckland One Rail and the Wellington rail network is operated by Transdev Wellington.
Hybrid urban-suburban rail systems exhibiting characteristics of both rapid transit and commuter rail serving a metropolitan region are common in German-speaking countries, where they are known as S-Bahn. Other examples include: Lazio regional railways in Rome, the RER in France and the Elizabeth line, London Underground Metropolitan line, London Overground and Merseyrail in the UK. A comparable system in India, the Delhi RRTS, is also under construction. | [
{
"paragraph_id": 0,
"text": "Commuter rail, or suburban rail, is a passenger rail transport service that primarily operates within a metropolitan area, connecting commuters to a central city from adjacent suburbs or commuter towns. Commuter rail systems are considered heavy rail, using electrified or diesel trains. Distance charges or zone pricing may be used.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The term can refer to systems with a wide variety of different features and service frequencies, but is often used in contrast to rapid transit or light rail.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Some services share similarities with both commuter rail and high-frequency rapid transit, examples being the German S-Bahn in some cities, the Réseau Express Régional (RER) in Paris, the S Lines in Milan, many Japanese commuter systems, the East Rail line in Hong Kong and some Australasian suburban networks, such as Sydney Trains. Some services, like British commuter rail, share tracks with other passenger services and freight.",
"title": ""
},
{
"paragraph_id": 3,
"text": "In North America, commuter rail sometimes refers only to systems that primarily operate during peak periods and offer little to no service for the rest of the day, with regional rail being used to refer to systems that offer all-day service.",
"title": ""
},
{
"paragraph_id": 4,
"text": "Most commuter (or suburban) trains are built to main line rail standards, differing from light rail or rapid transit (metro rail) systems by:",
"title": "Characteristics"
},
{
"paragraph_id": 5,
"text": "Compared to rapid transit (or metro rail), commuter/suburban rail often has lower frequency, following a schedule rather than fixed intervals, and fewer stations spaced further apart. They primarily serve lower density suburban areas (non inner-city), generally only having one or two stops in a city's central business district, and often share right-of-way with intercity or freight trains. Some services operate only during peak hours and others uses fewer departures during off peak hours and weekends. Average speeds are high, often 50 km/h (30 mph) or higher. These higher speeds better serve the longer distances involved. Some services include express services which skip some stations in order to run faster and separate longer distance riders from short-distance ones.",
"title": "Characteristics"
},
{
"paragraph_id": 6,
"text": "The general range of commuter trains' travel distance varies between 15 and 200 km (10 and 125 miles), but longer distances can be covered when the trains run between two or several cities (e.g. S-Bahn in the Ruhr area of Germany). Distances between stations may vary, but are usually much longer than those of urban rail systems. In city centers the train either has a terminal station or passes through the city centre with notably fewer station stops than those of urban rail systems. Toilets are often available on-board trains and in stations.",
"title": "Characteristics"
},
{
"paragraph_id": 7,
"text": "Their ability to coexist with freight or intercity services in the same right-of-way can drastically reduce system construction costs. However, frequently they are built with dedicated tracks within that right-of-way to prevent delays, especially where service densities have converged in the inner parts of the network.",
"title": "Characteristics"
},
{
"paragraph_id": 8,
"text": "Most such trains run on the local standard gauge track. Some systems may run on a narrower or broader gauge. Examples of narrow gauge systems are found in Japan, Indonesia, Malaysia, Thailand, Taiwan, Switzerland, in the Brisbane (Queensland Rail's City network) and Perth (Transperth) systems in Australia, in some systems in Sweden, and on the Genoa-Casella line in Italy. Some countries and regions, including Finland, India, Pakistan, Russia, Brazil and Sri Lanka, as well as San Francisco (BART) in the US and Melbourne and Adelaide in Australia, use broad gauge track.",
"title": "Characteristics"
},
{
"paragraph_id": 9,
"text": "Metro rail and rapid transit usually cover smaller inner-urban areas within 12 to 20 km (7 to 12 mi) of city centers, with shorter stop spacing, use rolling stocks with larger standing spaces, lower top speed and higher acceleration, designed for short-distance travel. They also run more frequently, to a headway rather than a published timetable and use dedicated tracks (underground or elevated), whereas commuter rail often shares tracks, technology and the legal framework within mainline railway systems, and uses rolling stocks with more seating and higher speed for comfort on longer city-suburban journeys.",
"title": "Characteristics"
},
{
"paragraph_id": 10,
"text": "However, the classification as a metro or rapid rail can be difficult as both may typically cover a metropolitan area exclusively, run on separate tracks in the centre, and often feature purpose-built rolling stock. The fact that the terminology is not standardised across countries (even across English-speaking countries) further complicates matters. This distinction is most easily made when there are two (or more) systems such as New York's subway and the LIRR and Metro-North Railroad, Paris' Métro and RER along with Transilien, Washington D.C.'s Metro along with its MARC and VRE, London's tube lines of the Underground and the Overground, Elizabeth line, Thameslink along with other commuter rail operators, Madrid's Metro and Cercanías, Barcelona's Metro and Rodalies, and Tokyo's subway and the JR lines along with various privately owned and operated commuter rail systems.",
"title": "Characteristics"
},
{
"paragraph_id": 11,
"text": "Regional rail usually provides rail services between towns and cities, rather than purely linking major population hubs in the way inter-city rail does. Regional rail operates outside major cities. Unlike Inter-city, it stops at most or all stations between cities. It provides a service between smaller communities along the line that are often byproducts of ribbon developments, and also connects with long-distance services at interchange stations located at junctions, terminals, or larger towns along the line. Alternative names are \"local train\" or \"stopping train\". Examples include the former BR's Regional Railways, France's TER (Transport express régional), Germany's Regionalexpress and Regionalbahn, and South Korea's Tonggeun services.",
"title": "Characteristics"
},
{
"paragraph_id": 12,
"text": "In some European countries, the distinction between commuter trains and long-distance/intercity trains is subtle, due to the relatively short distances involved. For example, so-called \"intercity\" trains in Belgium and the Netherlands carry many commuters, while their equipment, range, and speeds are similar to those of commuter trains in some larger countries.",
"title": "Characteristics"
},
{
"paragraph_id": 13,
"text": "The United Kingdom has a privatised rail system, with different routes and services covered by different private operators. The distinction between commuter and intercity rail is not as clear as it was before privatisation (when InterCity existed as a brand of its own), but usually it is still possible to tell them apart. Some operators, for example Thameslink, focus solely on commuter services. Others, such as Avanti West Coast and LNER, run solely intercity services. Others still, such as GWR and EMR, run a mixture of commuter, regional and intercity services. Some of these operators use different branding for different types of service (for example EMR brands its trains as either \"InterCity\", \"Connect\" for London commuter services, and \"Regional\") but even for those operators that do not, the type of train, amenities offered, and stopping pattern, usually tell the services apart.",
"title": "Characteristics"
},
{
"paragraph_id": 14,
"text": "Russian commuter trains, on the other hand, frequently cover areas larger than Belgium itself, although these are still short distances by Russian standards. They have a different ticketing system from long-distance trains, and in major cities they often operate from a separate section of the train station.",
"title": "Characteristics"
},
{
"paragraph_id": 15,
"text": "Some consider \"inter-city\" service to be that which operates as an express service between two main city stations, bypassing intermediate stations. However, this term is used in Australia (Sydney for example) to describe the regional trains operating beyond the boundaries of the suburban services, even though some of these \"inter-city\" services stop all stations similar to German regional services. In this regard, the German service delineations and naming conventions are clearer and better used for academic purposes.",
"title": "Characteristics"
},
{
"paragraph_id": 16,
"text": "Sometimes high-speed rail can serve daily use of commuters. The Japanese Shinkansen high speed rail system is heavily used by commuters in the Greater Tokyo Area, who commute between 100 and 200 km (62 and 124 mi) by Shinkansen. To meet the demand of commuters, JR sells commuter discount passes. Before 2021, they operated 16-car bilevel E4 Series Shinkansen trains at rush hour, providing a capacity of 1,600 seats. Several lines in China, such as the Beijing–Tianjin Intercity Railway and the Shanghai–Nanjing High-Speed Railway, serve a similar role with many more under construction or planned.",
"title": "Characteristics"
},
{
"paragraph_id": 17,
"text": "In South Korea, some sections of the high-speed rail network are also heavily used by commuters, such as the section between Gwangmyeong Station and Seoul Station on the KTX network (Gyeongbu HSR Line), or the section between Dongtan Station and Suseo station on the SRT Line.",
"title": "Characteristics"
},
{
"paragraph_id": 18,
"text": "The high-speed services linking Zürich, Bern and Basel in Switzerland (200 km/h (120 mph)) have brought the Central Business Districts (CBDs) of these three cities within 1 hour of each other. This has resulted in unexpectedly high demand for new commuter trips between the three cities and a corresponding increase in suburban rail passengers accessing the high-speed services at the main city-centre stations (Hauptbahnhof). The Regional-Express commuter service between Munich and Nuremberg in Germany runs at 200 km/h (120 mph) on the 300 km/h (186 mph) Nuremberg–Ingolstadt high-speed railway.",
"title": "Characteristics"
},
{
"paragraph_id": 19,
"text": "The regional trains Stockholm–Uppsala, Stockholm–Västerås, Stockholm–Eskilstuna and Gothenburg–Trollhättan in Sweden reach 200 km/h (120 mph) and have many daily commuters.",
"title": "Characteristics"
},
{
"paragraph_id": 20,
"text": "In Great Britain, the HS1 domestic services between London and Ashford runs at a top speed of 225 km/h, and in peak hours the trains can be full with commuters standing.",
"title": "Characteristics"
},
{
"paragraph_id": 21,
"text": "The Athens Suburban Railway in Greece consists of five lines, 4 of which are electrified. The Kiato–Piraeus line and the Aigio–Airport lines reach speeds of up to 180 km/h (112 mph). The Athens–Chalcis line is also expected to attain speeds of up to 200 km/h (124 mph) upon upgrading of the SKA–Oinoi railway sector. These lines also have many daily commuters, with the number expected to rise even higher upon full completion of the Acharnes Railway Center.",
"title": "Characteristics"
},
{
"paragraph_id": 22,
"text": "Eskişehir-Ankara and Konya-Ankara high speed train routes serve as high speed commuter trains in Turkey.",
"title": "Characteristics"
},
{
"paragraph_id": 23,
"text": "Commuter/suburban trains are usually optimized for maximum passenger volume, in most cases without sacrificing too much comfort and luggage space, though they seldom have all the amenities of long-distance trains. Cars may be single- or double-level, and aim to provide seating for all. Compared to intercity trains, they have less space, fewer amenities and limited baggage areas.",
"title": "Train types"
},
{
"paragraph_id": 24,
"text": "Commuter rail trains are usually composed of multiple units, which are self-propelled, bidirectional, articulated passenger rail cars with driving motors on each (or every other) bogie. Depending on local circumstances and tradition they may be powered either by diesel engines located below the passenger compartment (diesel multiple units) or by electricity picked up from third rails or overhead lines (electric multiple units). Multiple units are almost invariably equipped with control cabs at both ends, which is why such units are so frequently used to provide commuter services, due to the associated short turn-around time.",
"title": "Train types"
},
{
"paragraph_id": 25,
"text": "Locomotive hauled services are used in some countries or locations. This is often a case of asset sweating, by using a single large combined fleet for intercity and regional services. Loco hauled services are usually run in push-pull formation, that is, the train can run with the locomotive at the \"front\" or \"rear\" of the train (pushing or pulling). Trains are often equipped with a control cab at the other end of the train from the locomotive, allowing the train operator to operate the train from either end. The motive power for locomotive-hauled commuter trains may be either electric or diesel-electric, although some countries, such as Germany and some of the former Soviet-bloc countries, also use diesel-hydraulic locomotives.",
"title": "Train types"
},
{
"paragraph_id": 26,
"text": "In the US and some other countries, a three-and-two seat plan is used. Middle seats on these trains are often less popular because passengers feel crowded and uncomfortable.",
"title": "Train types"
},
{
"paragraph_id": 27,
"text": "In Japan, South Korea and Indonesia, longitudinal (sideways window-lining) seating is widely used in many commuter rail trains to increase capacity in rush hours. Carriages are usually not organized to increase seating capacity (although in some trains at least one carriage would feature more doors to facilitate easier boarding and alighting and bench seats so that they can be folded up during rush hour to provide more standing room) even in the case of commuting longer than 50 km and commuters in the Greater Tokyo Area, Seoul metropolitan area, and Jabodetabek area have to stand in the train for more than an hour.",
"title": "Train types"
},
{
"paragraph_id": 28,
"text": "Currently there are not many examples of commuter rail in Africa. Metrorail operates in the major cities of South Africa, and there are some commuter rail services in Algeria, Botswana, Kenya, Morocco, Egypt and Tunisia. In Algeria, SNTF operates commuter rail lines between the capital Algiers and its southern and eastern suburbs. They also serve to connect Algiers' main universities to each other. The Dar es Salaam commuter rail offers intracity services in Dar es Salaam, Tanzania. In Botswana, the (Botswana Railways) \"BR Express\" has a commuter train between Lobatse and Gaborone.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 29,
"text": "In Japan, commuter rail systems have extensive network and frequent service and are heavily used. In many cases, Japanese commuter rail is operationally more like a typical metro system (frequent trains, an emphasis on standing passengers, short station spacings) than it is like commuter rail in other countries. Japanese commuter rail commonly interline with city center subway lines, with commuter rail trains continuing into the subway network, and then out onto different commuter rail systems on the other side of the city. Many Japanese commuter systems operate various stopping patterns to reduce the travel time to distant locations, often using station passing loops instead of dedicated express tracks. It is notable that the larger Japanese commuter rail systems are owned and operated by for-profit private railway companies, without public subsidy.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 30,
"text": "East Japan Railway Company operates a large suburban train network in Tokyo with various lines connecting the suburban areas to the city center. While the Yamanote Line, Keihin Tohoku Line, Chūō–Sōbu Line services arguably are more akin to rapid transit with frequent stops, simple stopping patterns (relative to other JR East lines) no branching services and largely serving the inner suburbs; other services along the Chūō Rapid Line, Sōbu Rapid Line/Yokosuka Line, Ueno–Tokyo Line, Shōnan–Shinjuku Line etc. are mid-distance services from suburban lines in the outer reaches of Greater Tokyo through operating into these lines to form a high frequency corridor though central Tokyo.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 31,
"text": "Other commuter rail routes in Japan include:",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 32,
"text": "Commuter rail systems have been inaugurated in several cities in China such as Beijing, Shanghai, Zhengzhou, Wuhan, Changsha and the Pearl River Delta. With plans for large systems in northeastern Zhejiang, Jingjinji, and Yangtze River Delta areas. The level of service varies considerably from line to line ranging high to near high speeds. More developed and established lines such as the Guangshen Railway have more frequent metro-like service.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 33,
"text": "The two MTR lines which are owned and formerly operated by the Kowloon-Canton Railway Corporation (East Rail line and Tuen Ma line which is integrated from the former West Rail line and Ma On Shan line in 2021), then the \"KCR\"), and MTR's own Tung Chung line connect the new towns in New Territories and the city centre Kowloon together with frequent intervals, and some New Territories-bound trains terminate at intermediate stations, providing more frequent services in Kowloon and the towns closer to Kowloon. They use rolling stocks with a faster maximum speed and have longer stop spacing compard to other lines which only run in the inner urban area, but in order to maximise capacity and throughput, these rolling stocks have longitudinal seatings, 5 pairs of doors in each carriage with large standing spaces like the urban lines, and run as frequent as well. Most of the sections of these four lines are overground and some sections of the East Rail Line share tracks with intercity trains to mainland China. The three KCR lines are integrated into the MTR network since 2008 and most passengers do not need to exit and re-enter the system through separate fare gates and purchase separate tickets to transfer between such lines and the rest of the network (the exceptions are between the Tuen Ma line's East Tsim Sha Tsui station and the Tsuen Wan line's Tsim Sha Tsui station.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 34,
"text": "In Taiwan, the Western line in the Taipei-Taoyuan Metropolitan Area, Taichung Metropolitan Area and Tainan-Kaohsiung Metropolitan Area as well as the Neiwan-Liujia line in the Hsinchu Area are considered commuter rail.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 35,
"text": "In South Korea, the Seoul Metropolitan Subway includes a total of 22 lines, and some of its lines are suburban lines. This is especially the case for lines operated by Korail, such as the Gyeongui-Jungang Line, the Gyeongchun Line, the Suin-Bundang Line, or the Gyeonggang Line. Even some lines not operated by Korail, such as the AREX Line, the Seohae Line or the Shinbundang Line mostly function as commuter rail. Lastly, even for the \"numbered lines\" (1–9) of the Seoul Metropolitan Subway which mostly travel in the dense parts of Seoul, some track sections extend far outside of the city, and operate large sections at ground level, such as on the Line 1, Line 3 and Line 4. In Busan, the Donghae Line, while part of the Busan Metro system, mostly functions as a commuter rail line.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 36,
"text": "In Indonesia, the KRL Commuterline is the largest commuter rail system in the country, serving the Greater Jakarta. It connects the Jakarta city center with surrounding cities and sub-urbans in Banten and West Java provinces, including Depok, Bogor, Tangerang, Serpong, Rangkasbitung, Bekasi and Cikarang. In July 2015, KA Commuter Jabodetabek served more than 850,000 passengers per day, which is almost triple of the 2011 figures, but still less than 3.5% of all Jabodetabek commutes. Other commuter rail systems in Indonesia include the Metro Surabaya Commuter Line, Prambanan Express, KRL Commuterline Yogyakarta–Solo, Kedung Sepur, and the Greater Bandung Commuter.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 37,
"text": "In the Philippines, the Philippine National Railways has two commuter rail systems currently operational; the PNR Metro Commuter Line in the Greater Manila Area and the PNR Bicol Commuter in the Bicol Region. A new commuter rail line in Metro Manila, the North–South Commuter Railway, is currently under construction. Its North section is set to be partially opened by 2021.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 38,
"text": "In Malaysia, there are two commuter services operated by Keretapi Tanah Melayu. They are the KTM Komuter that serves Kuala Lumpur and the surrounding Klang Valley area, and the KTM Komuter Northern Sector that serves Greater Penang, Perak, Kedah and Perlis in the northern region of Peninsular Malaysia.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 39,
"text": "In Thailand, the Greater Bangkok Commuter rail and the Airport Rail Link serve the Bangkok Metropolitan Region. The SRT Red Lines, a new commuter line in Bangkok, started construction in 2009. It opened in 2021.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 40,
"text": "Another commuter rail system in Southeast Asia is the Yangon Circular Railway in Myanmar.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 41,
"text": "In India, commuter rail systems are present in major cities and form an important part of people's daily lives. Mumbai Suburban Railway, the oldest suburban rail system in Asia, carries more than 7.24 million commuters on a daily basis which constitutes more than half of the total daily passenger capacity of the Indian Railways itself. Kolkata Suburban Railway, one of the largest suburban railway networks in the world, consists of more than 450 stations and carries more than 3.5 million commuters per day. The Chennai Suburban Railway along with the Chennai MRTS, also covers over 300 stations and carries more than 2.5 million people daily to different areas in Chennai and its surroundings. Other commuter railways in India include the Hyderabad MMTS, Delhi Suburban Railway, Pune Suburban Railway and Lucknow-Kanpur Suburban Railway.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 42,
"text": "In 2020, Government of India approved Bengaluru Suburban Railway to connect Bengaluru and its suburbs. It will be unique and first of its kind in India as it will have metro like facilities and rolling stock.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 43,
"text": "In Bangladesh, there is one suburban rail called the Chittagong Circular Railway. Another suburban railway called the Dhaka Circular Railway is currently proposed.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 44,
"text": "Karachi in Pakistan has a circular railway since 1969.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 45,
"text": "In Iran, SYSTRA proposed 4 express lines similar to RER suburban lines in Paris. Tehran Metro is going to construct express lines. For instance, the Rahyab Behineh, a consultant for Tehran Metro, is studying Tehran Express Line 2. Tehran Metro currently has a commuter line, which is Line 5 between Tehran and Karaj. Isfahan has two lines to its suburbs Baharestan and Fuladshahr under construction, and a third line to Shahinshahr is planned.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 46,
"text": "In Turkey; Başkentray, İZBAN, Marmaray and Gaziray are well-known examples.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 47,
"text": "Major metropolitan areas in most European countries are usually served by extensive commuter/suburban rail systems. Well-known examples include BG Voz in Belgrade (Serbia), S-Bahn in Germany, Austria and German-speaking areas of Switzerland, Proastiakos in Greece, RER in France and Belgium, Servizio ferroviario suburbano in Italy, Cercanías and Rodalies (Catalonia) in Spain, CP Urban Services in Portugal, Esko in Prague and Ostrava (Czech Republic), HÉV in Budapest (Hungary) and DART in Dublin (Ireland).",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 48,
"text": "London has multiple commuter rail routes:",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 49,
"text": "The Merseyrail network in Liverpool consists of two commuter rail routes powered by third rail, both of which branch out at one end. At the other, the Northern Line continues out of the city centre to a mainline rail interchange, while the Wirral Line has a city-centre loop.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 50,
"text": "Birmingham has four suburban routes, one of which is operated with diesel trains.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 51,
"text": "The Tyneside Electrics system in Newcastle existed from 1904 to 1967 using DC third rail. British Rail did not have the budget to maintain the ageing electrification system. The Riverside Branch was closed, while the remaining lines were de-electrified. 13 years later, they were re-electrified using DC overhead wires, and now form the Tyne & Wear Metro Yellow Line.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 52,
"text": "Many of the rail services around Glasgow are branded as Strathclyde Partnership for Transport. The network includes most electrified Scottish rail routes.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 53,
"text": "The Metro run eleven services which feed into Leeds, connecting the city with commuter areas and neighbouring urban centres in the West Yorkshire Connurbation.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 54,
"text": "MetroWest is a proposed network in Bristol, northern Somerset & southern Gloucestershire. The four-tracking of the line between Bristol Temple Meads and Bristol Parkway stations will enable local rail services to be separated from long-distance trains.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 55,
"text": "The Réseau express régional d'Île-de-France (RER) is a commuter rail network in the agglomeration of Paris. In the centre the RER has high frequency underground corridors where several suburban branches feed similar to a rapid transit system.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 56,
"text": "Commuter rail systems in Germany are called S-Bahn. While in some major cities S-Bahn services run on separate lines exclusively other systems use the existing regional rail tracks.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 57,
"text": "Randstadspoor is a network of Sprinter train services in and around the city of Utrecht in the Netherlands. For the realisation of this network, new stations were opened. Separate tracks have been built for these trains, so they can call frequently without disturbing high-frequent Intercity services parallel to these routes. Similar systems are planned for The Hague and Rotterdam.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 58,
"text": "In Sweden, electrified commuter rail systems known as Pendeltåg are present in the cities of Stockholm and Gothenburg. The Stockholm commuter rail system, which began in 1968, shares railway tracks with inter-city trains and freight trains, but for the most part runs on its own dedicated tracks. It is primarily used to transport passengers from nearby towns and other suburban areas into the city centre, not for transportation inside the city centre. The Gothenburg commuter rail system, which began in 1960, is similar to the Stockholm system, but does fully share tracks with long-distance trains.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 59,
"text": "In Norway, the Oslo commuter rail system mostly shares tracks with more long-distance trains, but also runs on some local railways without other traffic. Services converge on a primary main line between Asker and Lillestrøm. Oslo has the largest commuter rail system in the Nordic countries in terms of line lengths and number of stations. But some lines have travel times (over an hour from Oslo) and frequencies (once per hour) which are more like regional trains. Also Bergen, Stavanger and Trondheim have commuter rail systems. These have only one or two lines each and they share tracks with other trains.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 60,
"text": "In Finland, the Helsinki commuter rail network runs on dedicated tracks from Helsinki Central railway station to Leppävaara and Kerava. The Ring Rail Line serves Helsinki Airport and northern suburbs of Vantaa and is exclusively used by the commuter rail network. On 15 December 2019, the Tampere region got its own commuter rail service, with trains running from Tampere to Nokia, Lempäälä and Orivesi.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 61,
"text": "In Spain, Cercanías networks exist in Madrid, Sevilla, Murcia/Alicante, San Sebastián, Cádiz, Valencia, Asturias, Santander, Zaragoza, Bilbao and Málaga. All these systems include underground sections in the city centre. There is also a network of narrow-gauge commuter systems in North Spain and Murcia.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 62,
"text": "Cercanías Madrid is one of the most important train services in the country, more than 900,000 passengers move in the system. It has underground stations in Madrid like Recoletos, Sol or Nuevos Ministerios and in the metropolitan area in cities like Parla or Getafe.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 63,
"text": "In the autonomous community of Catalonia, and unlike the rest of Spain, the commuter service is not managed by Renfe Operadora. Since 2010, the Government of Catalonia has managed all the regular commuter services with the \"transfer of Rodalies\". There are two companies that manage the Catalan commuter network:",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 64,
"text": "The Government of Catalonia will assume full control of the current R12 regional line in 2024 and it will be owned by the FGC. It will eliminate the current line and replace it with the new commuter lines RL3 and RL4, towards Cervera and Manresa from Lleida respectively.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 65,
"text": "In Italy there are several commuter rail networks:",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 66,
"text": "In Poland, commuter rail systems exist in Tricity, Warsaw, Kraków (SKA) and Katowice (SKR). There is also a similar system planned in Wrocław and Szczecin. The terms used are \"Szybka Kolej Miejska\" (fast urban rail) and \"kolej aglomeracyjna\" (agglomeration rail). These systems are:",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 67,
"text": "The Proastiakos (Greek: Προαστιακός; \"suburban\") is Greece's suburban railway (commuter rail) services, which are run by TrainOSE, on infrastructure owned by the Hellenic Railways Organisation (OSE). There are three Proastiakos networks, servicing the country's three largest cities: Athens, Thessaloniki and Patras. In particular, the Athenian network is undergoing modifications to completely separate it from mainline traffic, by re-routing the tracks via a tunnel underneath the city center. A similar project is planned for the Patras network, whereas a new line is due to be constructed for the Thessalonian network.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 68,
"text": "In Romania, the first commuter trains were introduced in December 2019. They operate between Bucharest and Funduea or Buftea.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 69,
"text": "BG Voz is an urban rail system that serves Belgrade. It currently has only two routes, with plans for further expansion. Between early 1990s and mid-2010s, there was another system, known as Beovoz, that was used to provide mass-transit service within the Belgrade metropolitan area, as well as to nearby towns, similarly to RER in Paris. Beovoz had more lines and far more stops than the current system. However, it was abandoned in favor of more accurate BG Voz, mostly due to inefficiency. While current services rely mostly on the existing infrastructure, any further development means furthering capacities (railways expansion and new trains). Plans for further extension of system include another two lines, one of which should reach Belgrade Nikola Tesla Airport.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 70,
"text": "In Russia, Ukraine and some other countries of the former Soviet Union, electrical multiple unit passenger suburban trains called Elektrichka are widespread. The first such system in Russia is the Oranienbaum Electric Line in St. Petersburg. In Moscow the Beskudnikovskaya railway branch existed between the 1940s and 1980s. The trains that shuttled along it did not go to the main lines, so it was a city transport. Today there are the Moscow Central Circle and the Moscow Central Diameters.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 71,
"text": "In Turkey, Marmaray line stations from Sirkeci to Halkalı are located at the European side. Overground section between Kazlıçeşme and Sirkeci, stations such as Cankurtaran, are closed since 2013.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 72,
"text": "In the United States, Canada, Costa Rica, El Salvador and Mexico regional passenger rail services are provided by governmental or quasi-governmental agencies, with the busiest and most expansive rail networks located in the Northeastern US, California, and Eastern Canada. Most North American commuter railways utilize diesel locomotive propulsion, with the exception of services in New York City, Philadelphia, Chicago, Denver, and Mexico City; New York's commuter rail lines use a combination of third rail and overhead wire power generation, while Chicago only has two out of twelve services that are electrified. Many newer and proposed systems in Canada and the United States are often are geared to serving peak-hour commutes as opposed to the all-day systems of Europe, East Asia, and Australia.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 73,
"text": "Eight commuter rail systems in the United States carried over ten million trips in 2018, those being in descending order:",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 74,
"text": "Other commuter rail systems in the United States (not in ridership order) are:",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 75,
"text": "Examples include an 899 km (559 mi) commuter system in the Buenos Aires metropolitan area, the 225 km (140 mi) long Supervia in Rio de Janeiro, the Metrotrén in Santiago, Chile, and the Valparaíso Metro in Valparaíso, Chile.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 76,
"text": "Another example is Companhia Paulista de Trens Metropolitanos (CPTM) in Greater São Paulo, Brazil. CPTM has 94 stations with seven lines, numbered starting on 7 (the lines 1 to 6 and the line 15 belong to the São Paulo Metro), with a total length of 273 kilometres (170 mi). Trains operates at high frequencies on tracks used exclusively for commuter traffic. In Rio de Janeiro SuperVia provides electrified commuter rail services.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 77,
"text": "The five major cities in Australia have suburban railway systems in their metropolitan areas. These networks have frequent services, with frequencies varying from every 10 to every 30 minutes on most suburban lines, and up to 3–5 minutes in peak on bundled underground lines in the city centres of Sydney, Brisbane, Perth and Melbourne. The networks in each state developed from mainline railways and have never been completely operationally separate from long distance and freight traffic, unlike metro systems. The suburban networks are almost completely electrified.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 78,
"text": "The main suburban rail networks in Australia are:",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 79,
"text": "New Zealand has two frequent suburban rail services comparable to those in Australia: the Auckland rail network is operated by Auckland One Rail and the Wellington rail network is operated by Transdev Wellington.",
"title": "Commuter rail systems around the world"
},
{
"paragraph_id": 80,
"text": "Hybrid urban-suburban rail systems exhibiting characteristics of both rapid transit and commuter rail serving a metropolitan region are common in German-speaking countries, where they are known as S-Bahn. Other examples include: Lazio regional railways in Rome, the RER in France and the Elizabeth line, London Underground Metropolitan line, London Overground and Merseyrail in the UK. A comparable system in India, the Delhi RRTS, is also under construction.",
"title": "Hybrid urban-suburban rail systems"
}
] | Commuter rail, or suburban rail, is a passenger rail transport service that primarily operates within a metropolitan area, connecting commuters to a central city from adjacent suburbs or commuter towns. Commuter rail systems are considered heavy rail, using electrified or diesel trains. Distance charges or zone pricing may be used. The term can refer to systems with a wide variety of different features and service frequencies, but is often used in contrast to rapid transit or light rail. Some services share similarities with both commuter rail and high-frequency rapid transit, examples being the German S-Bahn in some cities, the Réseau Express Régional (RER) in Paris, the S Lines in Milan, many Japanese commuter systems, the East Rail line in Hong Kong and some Australasian suburban networks, such as Sydney Trains. Some services, like British commuter rail, share tracks with other passenger services and freight. In North America, commuter rail sometimes refers only to systems that primarily operate during peak periods and offer little to no service for the rest of the day, with regional rail being used to refer to systems that offer all-day service. | 2001-09-07T10:20:05Z | 2023-12-28T21:32:51Z | [
"Template:Convert",
"Template:See also",
"Template:Lang-el",
"Template:Div col end",
"Template:Cite web",
"Template:Public transport",
"Template:Short description",
"Template:Redirect",
"Template:Portal bar",
"Template:Citation needed",
"Template:Expand section",
"Template:Div col",
"Template:Cite news",
"Template:More citations needed",
"Template:Multiple image",
"Template:Cite book",
"Template:Train topics",
"Template:Original research",
"Template:Reflist",
"Template:Cite journal",
"Template:Circular reference",
"Template:Main"
] | https://en.wikipedia.org/wiki/Commuter_rail |
6,288 | Cambridgeshire | Cambridgeshire (abbreviated Cambs.) is a ceremonial county in the East of England and East Anglia. It is bordered by Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and Northamptonshire to the west. The largest settlement is the city of Peterborough, and the city of Cambridge is the county town.
The county has an area of 3,389 km (1,309 sq mi) and a population of 852,523. Peterborough (179,349) and Cambridge (145,674), located in the north-west and south respectively, are by far the largest settlements. The remainder of the county is rural, and contains the city of Ely (20,112) and towns such as Wisbech and St Neots. Cambridgeshire contains six local government districts; five are part of a two-tier non-metropolitan county also called Cambridgeshire, and the district of Peterborough is a unitary area. The local authorities collaborate through Cambridgeshire and Peterbrough Combined Authority. The county did not historically include Huntingdonshire or the Soke of Peterborough, which was part of Northamptonshire.
The north and east of the county are dominated by the Fens, an extremely flat, drained marsh maintained by drainage ditches and dykes. Holme Fen is the UK's lowest physical point, at 2.75 m (9 ft) below sea level. The flatness of the landscape makes the few areas of higher ground, such as that Ely is built on, very conspicuous. The landscape in the south and west is gently undulating. Cambridgeshire's principal rivers are the Nene, which flows through the north of the county and is canalised east of Peterborough; the Great Ouse, which flows from west to east past Huntingdon and Ely; and the Cam, a tributary of the Great Ouse which flows through Cambridge.
Cambridgeshire is noted as the site of Flag Fen in Fengate, one of the earliest-known Neolithic permanent settlements in the United Kingdom, compared in importance to Balbridie in Aberdeen, Scotland. Must Farm quarry, at Whittlesey has been described as 'Britain's Pompeii due to its relatively good condition, including the 'best-preserved Bronze Age dwellings ever found'. A great quantity of archaeological finds from the Stone Age, the Bronze Age and the Iron Age were made in East Cambridgeshire. Most items were found in Isleham.
The area was settled by the Anglo-Saxons starting in the fifth century. Genetic testing on seven skeletons found in Anglo-Saxon era graves in Hinxton and Oakington found that five were either migrants or descended from migrants from the continent, one was a native Briton, and one had both continental and native ancestry, suggesting intermarriage.
Cambridgeshire was recorded in the Domesday Book as "Grantbridgeshire" (or rather Grentebrigescire) (related to the river Granta).
Covering a large part of East Anglia, Cambridgeshire today is the result of several local government unifications. In 1888 when county councils were introduced, separate councils were set up, following the traditional division of Cambridgeshire, for
In 1965, these two administrative counties were merged to form Cambridgeshire and the Isle of Ely. Under the Local Government Act 1972 this merged with the county to the west, Huntingdon and Peterborough, which had been formed in 1965, by the merger of Huntingdonshire with the Soke of Peterborough (the latter previously a part of Northamptonshire with its own county council). The resulting county was called simply Cambridgeshire.
Since 1998, the City of Peterborough has been separately administered as a unitary authority area. It is associated with Cambridgeshire for ceremonial purposes such as Lieutenancy and joint functions such as policing and the fire service.
In 2002, the conservation charity Plantlife unofficially designated Cambridgeshire's county flower as the Pasqueflower.
The Cambridgeshire Regiment (nicknamed the Fen Tigers), the county-based army unit, fought in the Boer War in South Africa, the First World War and Second World War.
Due to the county's flat terrain and proximity to the continent, during the Second World War the military built many airfields here for RAF Bomber Command, RAF Fighter Command, and the allied USAAF. In recognition of this collaboration, the Cambridge American Cemetery and Memorial is located in Madingley. It is the only WWII burial ground in England for American servicemen who died during that event.
Most English counties have nicknames for their people, such as a "Tyke" from Yorkshire and a "Yellowbelly" from Lincolnshire. The historical nicknames for people from Cambridgeshire are "Cambridgeshire Camel" or "Cambridgeshire Crane", referring to the wildfowl that were once abundant in the Fens. The term "Fen Tigers" is sometimes used to describe the people who live and work in the Fens.
Original historical documents relating to Cambridgeshire are held by Cambridgeshire Archives. Cambridgeshire County Council Libraries maintains several Local Studies collections of printed and published materials, significantly at the Cambridgeshire Collection held in the Cambridge Central Library.
Cambridgeshire's county flag was made official on 1 February 2015, after the design was selected as an entry from design competition that ran during 2014. The design features three golden crowns, two on the top, one on the bottom that are separated by two wavy lines in the middle. The crowns are meant to represent East Anglia, and the two lines represent the River Cam and are in the university's colours.
Large areas of the county are extremely low-lying and Holme Fen is notable for being the UK's lowest physical point at 2.75 m (9 ft) below sea level. The highest point of the modern administrative county is in the village of Great Chishill at 146 m (480 ft) above sea level. However, this parish was historically a part of Essex, having been moved to Cambridgeshire in boundary changes in 1895. The historic county top is close to the village of Castle Camps where a point on the disused RAF airfield reaches a height of 128 metres (420 ft) above sea level (grid reference TL 63282 41881).
Other prominent hills are Little Trees Hill and Wandlebury Hill (both at 74 m (243 ft)) in the Gog Magog Hills, Rivey Hill above Linton, Rowley's Hill and the Madingley Hills.
Wicken Fen is a 254.5-hectare (629-acre) biological Site of Special Scientific Interest west of Wicken. A large part of it is owned and managed by the National Trust.
Cambridgeshire contains all its green belt around the city of Cambridge, extending to places such as Waterbeach, Lode, Duxford, Little & Great Abington and other communities a few miles away in nearby districts, to afford a protection from the conurbation. It was first drawn up in the 1950s.
Cambridgeshire County Council is controlled by an alliance of the Liberal Democrats, the Labour Party and independent groups, while Peterborough City Council is currently controlled by a Conservative Party minority administration.
The county contains seven Parliamentary constituencies:
This is a chart of trend of regional gross value added of Cambridgeshire at current basic prices published (pp. 240–253) by Office for National Statistics with figures in millions of English Pounds Sterling.
AWG plc is based in Huntingdon. The RAF has several stations in the Huntingdon and St Ives area. RAF Alconbury, three miles north of Huntingdon, is being reorganised after a period of obsolescence following the departure of the USAF, to be the focus of RAF/USAFE intelligence operations, with activities at Upwood and Molesworth being transferred there. Most of Cambridgeshire is agricultural. Close to Cambridge is the so-called Silicon Fen area of high-technology (electronics, computing and biotechnology) companies. ARM Limited is based in Cherry Hinton. The inland Port of Wisbech on the River Nene is the county's only remaining port.
Cambridgeshire has a comprehensive education system with over 240 state schools, not including sixth form colleges. The independent sector includes King's Ely and Wisbech Grammar School, founded in 970 and 1379 respectively, they are two of the oldest schools in the country.
Some of the secondary schools act as Village Colleges, institutions unique to Cambridgeshire. For example, Comberton Village College.
Cambridgeshire is home to a number of institutes of higher education:
In addition, Cambridge Regional College and Huntingdonshire Regional College both offer a limited range of higher education courses in conjunction with partner universities.
These are the settlements in Cambridgeshire with a town charter, city status or a population over 5,000; for a complete list of settlements see list of places in Cambridgeshire.
See the List of Cambridgeshire settlements by population page for more detail.
The town of Newmarket is surrounded on three sides by Cambridgeshire, being connected by a narrow strip of land to the rest of Suffolk.
Cambridgeshire has seen 32,869 dwellings created from 2002 to 2013 and there are a further 35,360 planned new dwellings between 2016 and 2023.
Cambridgeshire has a maritime temperate climate which is broadly similar to the rest of the United Kingdom, though it is drier than the UK average due to its low altitude and easterly location, the prevailing southwesterly winds having already deposited moisture on higher ground further west. Average winter temperatures are cooler than the English average, due to Cambridgeshire's inland location and relative nearness to continental Europe, which results in the moderating maritime influence being less strong. Snowfall is slightly more common than in western areas, due to the relative winter coolness and easterly winds bringing occasional snow from the North Sea. In summer temperatures are average or slightly above, due to less cloud cover. It reaches 25 °C (77 °F) on around ten days each year, and is comparable to parts of Kent and East Anglia.
Various forms of football have been popular in Cambridgeshire since medieval times at least. In 1579 one match played at Chesterton between townspeople and University of Cambridge students ended in a violent brawl that led the Vice-Chancellor to issue a decree forbidding them to play "footeball" outside of college grounds. During the nineteenth century, several formulations of the laws of football, known as the Cambridge rules, were created by students at the university. One of these codes, dating from 1863, had a significant influence on the creation of the original laws of the Football Association.
Cambridgeshire is also the birthplace of bandy, now an IOC accepted sport. According to documents from 1813, Bury Fen Bandy Club was undefeated for 100 years. A member of the club, Charles Goodman Tebbutt, wrote down the first official rules in 1882. Tebbutt was instrumental in spreading the sport to many countries. Great Britain Bandy Association is based in Cambridgeshire.
Fen skating is a traditional form of skating in the Fenland. The National Ice Skating Association was set up in Cambridge in 1879, they took the top Fen skaters to the world speedskating championships where James Smart (skater) became world champion.
On 6–7 June 2015, the inaugural Tour of Cambridgeshire cycle race took place on closed roads across the county. The event was an official UCI qualification event, and consisted of a Time Trial on the 6th, and a Gran Fondo event on the 7th. The Gran Fondo event was open to the public, and over 6000 riders took part in the 128 km (80 mi) race.
The River Cam is the main river flowing through Cambridge, parts of the River Nene and River Great Ouse lie within the county. In 2021 the latter was used as the course for The Boat Race. The River Cam serves as the course for the university Lent Bumps and May Bumps and the non-college rowing organised by Cambridgeshire Rowing Association.
There is only one racecourse in Cambridgeshire, located at Huntingdon.
Cambridge is home to the Kettle's Yard gallery and the artist-run Aid and Abet project space. Nine miles west of Cambridge next to the village of Bourn is Wysing Arts Centre. Cambridge Open Studios is the region's large arts organisation with over 500 members. Every year, more than 370 artists open their doors to visitors during four weekends in July.
The annual Fenland Poet Laureate awards were instigated for poets in the North of the county in 2012 at Wisbech & Fenland Museum.
The county was visited by travelling companies of comedians in the Georgian period. These came from different companies. The Lincoln Circuit included, at various times, Wisbech and Whittlesey. The Wisbech Georgian theatre still survives as an operating theatre now known as The Angles Theatre. In Cambridge the ADC Theatre is the venue for the Footlights. | [
{
"paragraph_id": 0,
"text": "Cambridgeshire (abbreviated Cambs.) is a ceremonial county in the East of England and East Anglia. It is bordered by Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and Northamptonshire to the west. The largest settlement is the city of Peterborough, and the city of Cambridge is the county town.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The county has an area of 3,389 km (1,309 sq mi) and a population of 852,523. Peterborough (179,349) and Cambridge (145,674), located in the north-west and south respectively, are by far the largest settlements. The remainder of the county is rural, and contains the city of Ely (20,112) and towns such as Wisbech and St Neots. Cambridgeshire contains six local government districts; five are part of a two-tier non-metropolitan county also called Cambridgeshire, and the district of Peterborough is a unitary area. The local authorities collaborate through Cambridgeshire and Peterbrough Combined Authority. The county did not historically include Huntingdonshire or the Soke of Peterborough, which was part of Northamptonshire.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The north and east of the county are dominated by the Fens, an extremely flat, drained marsh maintained by drainage ditches and dykes. Holme Fen is the UK's lowest physical point, at 2.75 m (9 ft) below sea level. The flatness of the landscape makes the few areas of higher ground, such as that Ely is built on, very conspicuous. The landscape in the south and west is gently undulating. Cambridgeshire's principal rivers are the Nene, which flows through the north of the county and is canalised east of Peterborough; the Great Ouse, which flows from west to east past Huntingdon and Ely; and the Cam, a tributary of the Great Ouse which flows through Cambridge.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Cambridgeshire is noted as the site of Flag Fen in Fengate, one of the earliest-known Neolithic permanent settlements in the United Kingdom, compared in importance to Balbridie in Aberdeen, Scotland. Must Farm quarry, at Whittlesey has been described as 'Britain's Pompeii due to its relatively good condition, including the 'best-preserved Bronze Age dwellings ever found'. A great quantity of archaeological finds from the Stone Age, the Bronze Age and the Iron Age were made in East Cambridgeshire. Most items were found in Isleham.",
"title": "History"
},
{
"paragraph_id": 4,
"text": "The area was settled by the Anglo-Saxons starting in the fifth century. Genetic testing on seven skeletons found in Anglo-Saxon era graves in Hinxton and Oakington found that five were either migrants or descended from migrants from the continent, one was a native Briton, and one had both continental and native ancestry, suggesting intermarriage.",
"title": "History"
},
{
"paragraph_id": 5,
"text": "Cambridgeshire was recorded in the Domesday Book as \"Grantbridgeshire\" (or rather Grentebrigescire) (related to the river Granta).",
"title": "History"
},
{
"paragraph_id": 6,
"text": "Covering a large part of East Anglia, Cambridgeshire today is the result of several local government unifications. In 1888 when county councils were introduced, separate councils were set up, following the traditional division of Cambridgeshire, for",
"title": "History"
},
{
"paragraph_id": 7,
"text": "In 1965, these two administrative counties were merged to form Cambridgeshire and the Isle of Ely. Under the Local Government Act 1972 this merged with the county to the west, Huntingdon and Peterborough, which had been formed in 1965, by the merger of Huntingdonshire with the Soke of Peterborough (the latter previously a part of Northamptonshire with its own county council). The resulting county was called simply Cambridgeshire.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "Since 1998, the City of Peterborough has been separately administered as a unitary authority area. It is associated with Cambridgeshire for ceremonial purposes such as Lieutenancy and joint functions such as policing and the fire service.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "In 2002, the conservation charity Plantlife unofficially designated Cambridgeshire's county flower as the Pasqueflower.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "The Cambridgeshire Regiment (nicknamed the Fen Tigers), the county-based army unit, fought in the Boer War in South Africa, the First World War and Second World War.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "Due to the county's flat terrain and proximity to the continent, during the Second World War the military built many airfields here for RAF Bomber Command, RAF Fighter Command, and the allied USAAF. In recognition of this collaboration, the Cambridge American Cemetery and Memorial is located in Madingley. It is the only WWII burial ground in England for American servicemen who died during that event.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "Most English counties have nicknames for their people, such as a \"Tyke\" from Yorkshire and a \"Yellowbelly\" from Lincolnshire. The historical nicknames for people from Cambridgeshire are \"Cambridgeshire Camel\" or \"Cambridgeshire Crane\", referring to the wildfowl that were once abundant in the Fens. The term \"Fen Tigers\" is sometimes used to describe the people who live and work in the Fens.",
"title": "History"
},
{
"paragraph_id": 13,
"text": "Original historical documents relating to Cambridgeshire are held by Cambridgeshire Archives. Cambridgeshire County Council Libraries maintains several Local Studies collections of printed and published materials, significantly at the Cambridgeshire Collection held in the Cambridge Central Library.",
"title": "History"
},
{
"paragraph_id": 14,
"text": "Cambridgeshire's county flag was made official on 1 February 2015, after the design was selected as an entry from design competition that ran during 2014. The design features three golden crowns, two on the top, one on the bottom that are separated by two wavy lines in the middle. The crowns are meant to represent East Anglia, and the two lines represent the River Cam and are in the university's colours.",
"title": "Flag"
},
{
"paragraph_id": 15,
"text": "Large areas of the county are extremely low-lying and Holme Fen is notable for being the UK's lowest physical point at 2.75 m (9 ft) below sea level. The highest point of the modern administrative county is in the village of Great Chishill at 146 m (480 ft) above sea level. However, this parish was historically a part of Essex, having been moved to Cambridgeshire in boundary changes in 1895. The historic county top is close to the village of Castle Camps where a point on the disused RAF airfield reaches a height of 128 metres (420 ft) above sea level (grid reference TL 63282 41881).",
"title": "Geography"
},
{
"paragraph_id": 16,
"text": "Other prominent hills are Little Trees Hill and Wandlebury Hill (both at 74 m (243 ft)) in the Gog Magog Hills, Rivey Hill above Linton, Rowley's Hill and the Madingley Hills.",
"title": "Geography"
},
{
"paragraph_id": 17,
"text": "Wicken Fen is a 254.5-hectare (629-acre) biological Site of Special Scientific Interest west of Wicken. A large part of it is owned and managed by the National Trust.",
"title": "Geography"
},
{
"paragraph_id": 18,
"text": "Cambridgeshire contains all its green belt around the city of Cambridge, extending to places such as Waterbeach, Lode, Duxford, Little & Great Abington and other communities a few miles away in nearby districts, to afford a protection from the conurbation. It was first drawn up in the 1950s.",
"title": "Geography"
},
{
"paragraph_id": 19,
"text": "Cambridgeshire County Council is controlled by an alliance of the Liberal Democrats, the Labour Party and independent groups, while Peterborough City Council is currently controlled by a Conservative Party minority administration.",
"title": "Politics"
},
{
"paragraph_id": 20,
"text": "The county contains seven Parliamentary constituencies:",
"title": "Politics"
},
{
"paragraph_id": 21,
"text": "This is a chart of trend of regional gross value added of Cambridgeshire at current basic prices published (pp. 240–253) by Office for National Statistics with figures in millions of English Pounds Sterling.",
"title": "Economy"
},
{
"paragraph_id": 22,
"text": "AWG plc is based in Huntingdon. The RAF has several stations in the Huntingdon and St Ives area. RAF Alconbury, three miles north of Huntingdon, is being reorganised after a period of obsolescence following the departure of the USAF, to be the focus of RAF/USAFE intelligence operations, with activities at Upwood and Molesworth being transferred there. Most of Cambridgeshire is agricultural. Close to Cambridge is the so-called Silicon Fen area of high-technology (electronics, computing and biotechnology) companies. ARM Limited is based in Cherry Hinton. The inland Port of Wisbech on the River Nene is the county's only remaining port.",
"title": "Economy"
},
{
"paragraph_id": 23,
"text": "Cambridgeshire has a comprehensive education system with over 240 state schools, not including sixth form colleges. The independent sector includes King's Ely and Wisbech Grammar School, founded in 970 and 1379 respectively, they are two of the oldest schools in the country.",
"title": "Education"
},
{
"paragraph_id": 24,
"text": "Some of the secondary schools act as Village Colleges, institutions unique to Cambridgeshire. For example, Comberton Village College.",
"title": "Education"
},
{
"paragraph_id": 25,
"text": "Cambridgeshire is home to a number of institutes of higher education:",
"title": "Education"
},
{
"paragraph_id": 26,
"text": "In addition, Cambridge Regional College and Huntingdonshire Regional College both offer a limited range of higher education courses in conjunction with partner universities.",
"title": "Education"
},
{
"paragraph_id": 27,
"text": "These are the settlements in Cambridgeshire with a town charter, city status or a population over 5,000; for a complete list of settlements see list of places in Cambridgeshire.",
"title": "Settlements"
},
{
"paragraph_id": 28,
"text": "See the List of Cambridgeshire settlements by population page for more detail.",
"title": "Settlements"
},
{
"paragraph_id": 29,
"text": "The town of Newmarket is surrounded on three sides by Cambridgeshire, being connected by a narrow strip of land to the rest of Suffolk.",
"title": "Settlements"
},
{
"paragraph_id": 30,
"text": "Cambridgeshire has seen 32,869 dwellings created from 2002 to 2013 and there are a further 35,360 planned new dwellings between 2016 and 2023.",
"title": "Settlements"
},
{
"paragraph_id": 31,
"text": "Cambridgeshire has a maritime temperate climate which is broadly similar to the rest of the United Kingdom, though it is drier than the UK average due to its low altitude and easterly location, the prevailing southwesterly winds having already deposited moisture on higher ground further west. Average winter temperatures are cooler than the English average, due to Cambridgeshire's inland location and relative nearness to continental Europe, which results in the moderating maritime influence being less strong. Snowfall is slightly more common than in western areas, due to the relative winter coolness and easterly winds bringing occasional snow from the North Sea. In summer temperatures are average or slightly above, due to less cloud cover. It reaches 25 °C (77 °F) on around ten days each year, and is comparable to parts of Kent and East Anglia.",
"title": "Climate"
},
{
"paragraph_id": 32,
"text": "Various forms of football have been popular in Cambridgeshire since medieval times at least. In 1579 one match played at Chesterton between townspeople and University of Cambridge students ended in a violent brawl that led the Vice-Chancellor to issue a decree forbidding them to play \"footeball\" outside of college grounds. During the nineteenth century, several formulations of the laws of football, known as the Cambridge rules, were created by students at the university. One of these codes, dating from 1863, had a significant influence on the creation of the original laws of the Football Association.",
"title": "Culture"
},
{
"paragraph_id": 33,
"text": "Cambridgeshire is also the birthplace of bandy, now an IOC accepted sport. According to documents from 1813, Bury Fen Bandy Club was undefeated for 100 years. A member of the club, Charles Goodman Tebbutt, wrote down the first official rules in 1882. Tebbutt was instrumental in spreading the sport to many countries. Great Britain Bandy Association is based in Cambridgeshire.",
"title": "Culture"
},
{
"paragraph_id": 34,
"text": "Fen skating is a traditional form of skating in the Fenland. The National Ice Skating Association was set up in Cambridge in 1879, they took the top Fen skaters to the world speedskating championships where James Smart (skater) became world champion.",
"title": "Culture"
},
{
"paragraph_id": 35,
"text": "On 6–7 June 2015, the inaugural Tour of Cambridgeshire cycle race took place on closed roads across the county. The event was an official UCI qualification event, and consisted of a Time Trial on the 6th, and a Gran Fondo event on the 7th. The Gran Fondo event was open to the public, and over 6000 riders took part in the 128 km (80 mi) race.",
"title": "Culture"
},
{
"paragraph_id": 36,
"text": "The River Cam is the main river flowing through Cambridge, parts of the River Nene and River Great Ouse lie within the county. In 2021 the latter was used as the course for The Boat Race. The River Cam serves as the course for the university Lent Bumps and May Bumps and the non-college rowing organised by Cambridgeshire Rowing Association.",
"title": "Culture"
},
{
"paragraph_id": 37,
"text": "There is only one racecourse in Cambridgeshire, located at Huntingdon.",
"title": "Culture"
},
{
"paragraph_id": 38,
"text": "Cambridge is home to the Kettle's Yard gallery and the artist-run Aid and Abet project space. Nine miles west of Cambridge next to the village of Bourn is Wysing Arts Centre. Cambridge Open Studios is the region's large arts organisation with over 500 members. Every year, more than 370 artists open their doors to visitors during four weekends in July.",
"title": "Culture"
},
{
"paragraph_id": 39,
"text": "The annual Fenland Poet Laureate awards were instigated for poets in the North of the county in 2012 at Wisbech & Fenland Museum.",
"title": "Culture"
},
{
"paragraph_id": 40,
"text": "The county was visited by travelling companies of comedians in the Georgian period. These came from different companies. The Lincoln Circuit included, at various times, Wisbech and Whittlesey. The Wisbech Georgian theatre still survives as an operating theatre now known as The Angles Theatre. In Cambridge the ADC Theatre is the venue for the Footlights.",
"title": "Culture"
}
] | Cambridgeshire is a ceremonial county in the East of England and East Anglia. It is bordered by Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and Northamptonshire to the west. The largest settlement is the city of Peterborough, and the city of Cambridge is the county town. The county has an area of 3,389 km2 (1,309 sq mi) and a population of 852,523. Peterborough (179,349) and Cambridge (145,674), located in the north-west and south respectively, are by far the largest settlements. The remainder of the county is rural, and contains the city of Ely (20,112) and towns such as Wisbech and St Neots. Cambridgeshire contains six local government districts; five are part of a two-tier non-metropolitan county also called Cambridgeshire, and the district of Peterborough is a unitary area. The local authorities collaborate through Cambridgeshire and Peterbrough Combined Authority. The county did not historically include Huntingdonshire or the Soke of Peterborough, which was part of Northamptonshire. The north and east of the county are dominated by the Fens, an extremely flat, drained marsh maintained by drainage ditches and dykes. Holme Fen is the UK's lowest physical point, at 2.75 m (9 ft) below sea level. The flatness of the landscape makes the few areas of higher ground, such as that Ely is built on, very conspicuous. The landscape in the south and west is gently undulating. Cambridgeshire's principal rivers are the Nene, which flows through the north of the county and is canalised east of Peterborough; the Great Ouse, which flows from west to east past Huntingdon and Ely; and the Cam, a tributary of the Great Ouse which flows through Cambridge. | 2001-09-07T11:49:56Z | 2023-12-06T12:37:43Z | [
"Template:Party name with colour",
"Template:Curlie",
"Template:Cambridgeshire",
"Template:Authority control",
"Template:Main",
"Template:Further",
"Template:More citations needed section",
"Template:Cite journal",
"Template:Webarchive",
"Template:Cite news",
"Template:England counties",
"Template:Use dmy dates",
"Template:Main category",
"Template:Refbegin",
"Template:Adjacent communities",
"Template:Notelist",
"Template:Reflist",
"Template:Cite web",
"Template:Commons category",
"Template:About",
"Template:NoteTag",
"Template:Main list",
"Template:Redirect",
"Template:Cambridge weatherbox",
"Template:EngPlacesKey",
"Template:Columns-list",
"Template:NoteFoot",
"Template:Infobox English county",
"Template:Use British English",
"Template:Convert",
"Template:Cite EB1911",
"Template:Cite book",
"Template:Dead link",
"Template:Cite EB9",
"Template:Refend",
"Template:Short description"
] | https://en.wikipedia.org/wiki/Cambridgeshire |
6,290 | Christian Goldbach | Christian Goldbach (/ˈɡoʊldbɑːk/; German: [ˈɡɔltbax]; 18 March 1690 – 20 November 1764) was a Prussian mathematician connected with some important research mainly in number theory; he also studied law and took an interest in and a role in the Russian court. After traveling around Europe in his early life, he landed in Russia in 1725 as a professor at the newly founded Saint Petersburg Academy of Sciences. Goldbach jointly led the Academy in 1737. However, he relinquished duties in the Academy in 1742 and worked in the Russian Ministry of Foreign Affairs until his death in 1764. He is remembered today for Goldbach's conjecture and the Goldbach–Euler Theorem. He had a close friendship with famous mathematician Leonard Euler, serving as inspiration for Euler's mathematical pursuits.
Born in the Duchy of Prussia's capital Königsberg, part of Brandenburg-Prussia, Goldbach was the son of a pastor. He studied at the Royal Albertus University. After finishing his studies he went on long educational trips from 1710 to 1724 through Europe, visiting other German states, England, the Netherlands, Italy, and France, meeting with many famous mathematicians, such as Gottfried Leibniz, Leonhard Euler, and Nicholas I Bernoulli. These acquaintances started Goldbach's interest in mathematics. He briefly attended Oxford University in 1713 and, while he was there, Goldbach studied mathematics with John Wallis and Isaac Newton. Also, Goldbach's travels fostered his interest in philology, archaeology, metaphysics, ballistics, and medicine. Between 1717 and 1724, Goldbach published his first few papers which, while minor, credited his mathematical ability. Back in Königsberg, he became acquainted with Georg Bernhard Bilfinger and Jakob Hermann.
Goldbach followed Bilfinger and Hermann to the newly opened St. Petersburg Academy of Sciences in 1725. Christian Wolff had invited and had written recommendations for all the Germans who traveled to Saint Petersburg for the academy except Goldbach. Goldbach wrote to the president-designate of the academy, petitioning for a position in the academy, using his past publications and knowledge in medicine and law as qualifications. Goldbach was then hired to a five-year contract as a professor of mathematics and historian of the academy. As historian of the academy, he recorded each academy meeting from the opening of the school in 1725 until January 1728. Goldbach worked with famous mathematicians like Leonhard Euler, Daniel Bernoulli, Johann Bernoulli, and Jean le Rond d'Alembert. Goldbach also played a part in Euler's decision to academically pursue mathematics instead of medicine, cementing mathematics as the premier research field of the academy in the 1730s.
In 1728, when Peter II became Tsar of Russia, Goldbach became Peter II and Anna's, Peter II's cousin, tutor. Peter II moved the Russian court from St. Petersburg to Moscow in 1729, so Goldbach followed him to Moscow. Goldbach started a correspondence with Euler in 1729, in which some of Goldbach's most important mathematics contributions can be found. Upon Peter II's death in 1730, Goldbach stopped teaching but continued to assist Empress Anna. In 1732, Goldbach returned to the St. Petersburg Academy of Sciences and stayed in the Russian government when Anna moved the court back to St. Petersburg. Upon return to the academy, Goldbach was named corresponding secretary. With Goldbach's return, his friend Euler continued his teaching and research at the academy as well. Then, in 1737, Goldbach and J.D. Schumacher took over the administration of the academy. Also, Goldbach took on duty in Russian court under Empress Anna. He managed to retain his influence in court after the death of Anna and the rule of Empress Elizabeth. In 1742 he entered the Russian Ministry of Foreign Affairs, stepping away from the academy once more. Goldbach was gifted land and increased salary for his good work and rise in the Russian government. In 1760, Goldbach created new guidelines for the education of the royal children which would remain in place for 100 years. He died on 20 November 1764, aged 74, in Moscow.
Christian Goldbach was multilingual – he wrote a diary in German and Latin, his letters were written in German, Latin, French, and Italian and for official documents he used Russian, German and Latin.
Goldbach is most noted for his correspondence with Leibniz, Euler, and Bernoulli, especially in his 1742 letter to Euler stating his Goldbach's conjecture. He also studied and proved some theorems on perfect powers, such as the Goldbach–Euler theorem, and made several notable contributions to analysis. He also proved a result concerning Fermat numbers that is called Goldbach's theorem.
It is Goldbach and Euler's correspondence that contains some of Goldbach's most important contributions to mathematics, specifically number theory. Goldbach and Euler's friendship survived Goldbach's move to Moscow in 1728 and communication ensued. Their correspondence spanned 196 letters over 35 years written in Latin, German, and French. These letters spanned a wide range of topics, including various mathematics topics. Goldbach was the leading influence on Euler's interest and work in number theory. Most of the letters discuss Euler's research in number theory as well as differential calculus. Until the late 1750s, Euler's correspondence on his number theory research was almost exclusively with Goldbach.
Goldbach's earlier mathematical work and ideas in letters to Euler directly influenced some of Euler's work. In 1729, Euler solved two problems pertaining to sequences which had stumped Goldbach. Ensuingly, Euler outlined the solutions to Goldbach. Also, in 1729 Goldbach closely approximated the Basel problem, which prompted Euler's interest and concurring breakthrough solution. Goldbach, through his letters, kept Euler focused on number theory in the 1730s by discussing Fermat's conjecture with Euler. Euler subsequently offered a proof to the conjecture, crediting Goldbach with introducing him to the subfield. Euler proceeded to write 560 writings, published posthumously in four volumes of Opera omnia, with Goldbach's influence guiding some of the writings. Goldbach's famous conjecture and his writings with Euler prove him to be one of a handful of mathematicians who understood complex number theory in light of Fermat's revolutionary ideas on the topic. | [
{
"paragraph_id": 0,
"text": "Christian Goldbach (/ˈɡoʊldbɑːk/; German: [ˈɡɔltbax]; 18 March 1690 – 20 November 1764) was a Prussian mathematician connected with some important research mainly in number theory; he also studied law and took an interest in and a role in the Russian court. After traveling around Europe in his early life, he landed in Russia in 1725 as a professor at the newly founded Saint Petersburg Academy of Sciences. Goldbach jointly led the Academy in 1737. However, he relinquished duties in the Academy in 1742 and worked in the Russian Ministry of Foreign Affairs until his death in 1764. He is remembered today for Goldbach's conjecture and the Goldbach–Euler Theorem. He had a close friendship with famous mathematician Leonard Euler, serving as inspiration for Euler's mathematical pursuits.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Born in the Duchy of Prussia's capital Königsberg, part of Brandenburg-Prussia, Goldbach was the son of a pastor. He studied at the Royal Albertus University. After finishing his studies he went on long educational trips from 1710 to 1724 through Europe, visiting other German states, England, the Netherlands, Italy, and France, meeting with many famous mathematicians, such as Gottfried Leibniz, Leonhard Euler, and Nicholas I Bernoulli. These acquaintances started Goldbach's interest in mathematics. He briefly attended Oxford University in 1713 and, while he was there, Goldbach studied mathematics with John Wallis and Isaac Newton. Also, Goldbach's travels fostered his interest in philology, archaeology, metaphysics, ballistics, and medicine. Between 1717 and 1724, Goldbach published his first few papers which, while minor, credited his mathematical ability. Back in Königsberg, he became acquainted with Georg Bernhard Bilfinger and Jakob Hermann.",
"title": "Biography"
},
{
"paragraph_id": 2,
"text": "Goldbach followed Bilfinger and Hermann to the newly opened St. Petersburg Academy of Sciences in 1725. Christian Wolff had invited and had written recommendations for all the Germans who traveled to Saint Petersburg for the academy except Goldbach. Goldbach wrote to the president-designate of the academy, petitioning for a position in the academy, using his past publications and knowledge in medicine and law as qualifications. Goldbach was then hired to a five-year contract as a professor of mathematics and historian of the academy. As historian of the academy, he recorded each academy meeting from the opening of the school in 1725 until January 1728. Goldbach worked with famous mathematicians like Leonhard Euler, Daniel Bernoulli, Johann Bernoulli, and Jean le Rond d'Alembert. Goldbach also played a part in Euler's decision to academically pursue mathematics instead of medicine, cementing mathematics as the premier research field of the academy in the 1730s.",
"title": "Biography"
},
{
"paragraph_id": 3,
"text": "In 1728, when Peter II became Tsar of Russia, Goldbach became Peter II and Anna's, Peter II's cousin, tutor. Peter II moved the Russian court from St. Petersburg to Moscow in 1729, so Goldbach followed him to Moscow. Goldbach started a correspondence with Euler in 1729, in which some of Goldbach's most important mathematics contributions can be found. Upon Peter II's death in 1730, Goldbach stopped teaching but continued to assist Empress Anna. In 1732, Goldbach returned to the St. Petersburg Academy of Sciences and stayed in the Russian government when Anna moved the court back to St. Petersburg. Upon return to the academy, Goldbach was named corresponding secretary. With Goldbach's return, his friend Euler continued his teaching and research at the academy as well. Then, in 1737, Goldbach and J.D. Schumacher took over the administration of the academy. Also, Goldbach took on duty in Russian court under Empress Anna. He managed to retain his influence in court after the death of Anna and the rule of Empress Elizabeth. In 1742 he entered the Russian Ministry of Foreign Affairs, stepping away from the academy once more. Goldbach was gifted land and increased salary for his good work and rise in the Russian government. In 1760, Goldbach created new guidelines for the education of the royal children which would remain in place for 100 years. He died on 20 November 1764, aged 74, in Moscow.",
"title": "Biography"
},
{
"paragraph_id": 4,
"text": "Christian Goldbach was multilingual – he wrote a diary in German and Latin, his letters were written in German, Latin, French, and Italian and for official documents he used Russian, German and Latin.",
"title": "Biography"
},
{
"paragraph_id": 5,
"text": "Goldbach is most noted for his correspondence with Leibniz, Euler, and Bernoulli, especially in his 1742 letter to Euler stating his Goldbach's conjecture. He also studied and proved some theorems on perfect powers, such as the Goldbach–Euler theorem, and made several notable contributions to analysis. He also proved a result concerning Fermat numbers that is called Goldbach's theorem.",
"title": "Contributions"
},
{
"paragraph_id": 6,
"text": "It is Goldbach and Euler's correspondence that contains some of Goldbach's most important contributions to mathematics, specifically number theory. Goldbach and Euler's friendship survived Goldbach's move to Moscow in 1728 and communication ensued. Their correspondence spanned 196 letters over 35 years written in Latin, German, and French. These letters spanned a wide range of topics, including various mathematics topics. Goldbach was the leading influence on Euler's interest and work in number theory. Most of the letters discuss Euler's research in number theory as well as differential calculus. Until the late 1750s, Euler's correspondence on his number theory research was almost exclusively with Goldbach.",
"title": "Contributions"
},
{
"paragraph_id": 7,
"text": "Goldbach's earlier mathematical work and ideas in letters to Euler directly influenced some of Euler's work. In 1729, Euler solved two problems pertaining to sequences which had stumped Goldbach. Ensuingly, Euler outlined the solutions to Goldbach. Also, in 1729 Goldbach closely approximated the Basel problem, which prompted Euler's interest and concurring breakthrough solution. Goldbach, through his letters, kept Euler focused on number theory in the 1730s by discussing Fermat's conjecture with Euler. Euler subsequently offered a proof to the conjecture, crediting Goldbach with introducing him to the subfield. Euler proceeded to write 560 writings, published posthumously in four volumes of Opera omnia, with Goldbach's influence guiding some of the writings. Goldbach's famous conjecture and his writings with Euler prove him to be one of a handful of mathematicians who understood complex number theory in light of Fermat's revolutionary ideas on the topic.",
"title": "Contributions"
}
] | Christian Goldbach was a Prussian mathematician connected with some important research mainly in number theory; he also studied law and took an interest in and a role in the Russian court. After traveling around Europe in his early life, he landed in Russia in 1725 as a professor at the newly founded Saint Petersburg Academy of Sciences. Goldbach jointly led the Academy in 1737. However, he relinquished duties in the Academy in 1742 and worked in the Russian Ministry of Foreign Affairs until his death in 1764. He is remembered today for Goldbach's conjecture and the Goldbach–Euler Theorem. He had a close friendship with famous mathematician Leonard Euler, serving as inspiration for Euler's mathematical pursuits. | 2002-02-23T18:13:34Z | 2023-12-25T12:33:33Z | [
"Template:Infobox scientist",
"Template:IPAc-en",
"Template:Cite web",
"Template:Cite encyclopedia",
"Template:Commons category-inline",
"Template:Authority control",
"Template:Short description",
"Template:IPA-de",
"Template:Reflist",
"Template:Cite book",
"Template:Cite journal",
"Template:ISBN",
"Template:MacTutor Biography"
] | https://en.wikipedia.org/wiki/Christian_Goldbach |
6,291 | Roman censor | The censor was a magistrate in ancient Rome who was responsible for maintaining the census, supervising public morality, and overseeing certain aspects of the government's finances.
The power of the censor was absolute: no magistrate could oppose his decisions, and only another censor who succeeded him could cancel those decisions.
The censor's regulation of public morality is the origin of the modern meaning of the words censor and censorship.
The census was first instituted by Servius Tullius, sixth king of Rome, c. 575–535 BC. After the abolition of the monarchy and the founding of the Republic in 509 BC, the consuls had responsibility for the census until 443 BC. In 442 BC, no consuls were elected, but tribunes with consular power were appointed instead. This was a move by the plebeians to try to attain higher magistracies: only patricians could be elected consuls, while some military tribunes were plebeians. To prevent the possibility of plebeians obtaining control of the census, the patricians removed the right to take the census from the consuls and tribunes, and appointed for this duty two magistrates, called censores (censors), elected exclusively from the patricians in Rome.
The magistracy continued to be controlled by patricians until 351 BC, when Gaius Marcius Rutilus was appointed the first plebeian censor. Twelve years later, in 339 BC, one of the Publilian laws required that one censor had to be a plebeian. Despite this, no plebeian censor performed the solemn purification of the people (the lustrum; Livy Periochae 13) until 280 BC. In 131 BC, for the first time, both censors were plebeians.
The reason for having two censors was that the two consuls had previously taken the census together. If one of the censors died during his term of office, another was chosen to replace him, just as with consuls. This happened only once, in 393 BC. However, the Gauls captured Rome in that lustrum (five-year period), and the Romans thereafter regarded such replacement as "an offense against religion". From then on, if one of the censors died, his colleague resigned, and two new censors were chosen to replace them.
The office of censor was limited to eighteen months by a law proposed by the dictator Mamercus Aemilius Mamercinus. During the censorship of Appius Claudius Caecus (312–308 BC) the prestige of the censorship massively increased. Caecus built the first-ever Roman road (the Via Appia) and the first Roman aqueduct (the Aqua Appia), both named after him. He changed the organisation of the Roman tribes and was the first censor to draw the list of senators. He also advocated the founding of Roman coloniae throughout Latium and Campania to support the Roman war effort in the Second Samnite War. With these efforts and reforms, Appius Claudius Caecus was able to hold the censorship for a whole lustrum (five-year period), and the office of censor, subsequently entrusted with various important duties, eventually attained one of the highest political statuses in the Roman Republic, second only to that of the consuls.
The censors were elected in the Centuriate Assembly, which met under the presidency of a consul. Barthold Niebuhr suggests that the censors were at first elected by the Curiate Assembly, and that the Assembly's selections were confirmed by the Centuriate, but William Smith believes that "there is no authority for this supposition, and the truth of it depends entirely upon the correctness of [Niebuhr's] views respecting the election of the consuls". Both censors had to be elected on the same day, and accordingly if the voting for the second was not finished in the same day, the election of the first was invalidated, and a new assembly had to be held.
The assembly for the election of the censors was held under different auspices from those at the election of the consuls and praetors, so the censors were not regarded as their colleagues, although they likewise possessed the maxima auspicia. The assembly was held by the new consuls shortly after they began their term of office; and the censors, as soon as they were elected and the censorial power had been granted to them by a decree of the Centuriate Assembly (lex centuriata), were fully installed in their office.
As a general principle, the only ones eligible for the office of censor were those who had previously been consuls, but there were a few exceptions. At first, there was no law to prevent a person being censor twice, but the only person who was elected to the office twice was Gaius Marcius Rutilus in 265 BC. In that year, he originated a law stating that no one could be elected censor twice. In consequence of this, he received the cognomen of Censorinus.
The censorship differed from all other Roman magistracies in the length of office. The censors were originally chosen for a whole lustrum (a period of five years), but as early as ten years after its institution (433 BC) their office was limited to eighteen months by a law of Dictator Mamercus Aemilius Mamercinus. The censors were also unique with respect to rank and dignity. They had no imperium, and accordingly no lictors. Their rank was granted to them by the Centuriate Assembly, and not by the curiae, and in that respect they were inferior in power to the consuls and praetors.
Notwithstanding this, the censorship was regarded as the highest dignity in the state, with the exception of the dictatorship; it was a "sacred magistracy" (sanctus magistratus), to which the deepest reverence was due. The high rank and dignity which the censorship obtained was due to the various important duties gradually entrusted to it, and especially to its possessing the regimen morum, or general control over the conduct and the morals of the citizens. In the exercise of this power, they were regulated solely by their own views of duty, and were not responsible to any other power in the state.
The censors possessed the official stool called a "curule chair" (sella curulis), but some doubt exists with respect to their official dress. A well-known passage of Polybius describes the use of the imagines at funerals; we may conclude that a consul or praetor wore the purple-bordered toga praetexta, one who triumphed the embroidered toga picta, and the censor a purple toga peculiar to him, but other writers speak of their official dress as being the same as that of the other higher magistrates. The funeral of a censor was always conducted with great pomp and splendour, and hence a "censorial funeral" (funus censorium) was voted even to the emperors.
The censorship continued in existence for 421 years, from 443 BC to 22 BC, but during this period, many lustra passed by without any censor being chosen at all. According to one statement, the office was abolished by Lucius Cornelius Sulla. Although the authority on which this statement rests is not of much weight, the fact itself is probable, since there was no census during the two lustra which elapsed from Sulla's dictatorship to Gnaeus Pompeius Magnus (Pompey)'s first consulship (82–70 BC), and any strict "imposition of morals" would have been found inconvenient to the aristocracy that supported Sulla.
If the censorship had been done away with by Sulla, it was at any rate restored in the consulship of Pompey and Marcus Licinius Crassus. Its power was limited by one of the laws of the tribune Publius Clodius Pulcher (58 BC), which prescribed certain regular forms of proceeding before the censors in expelling a person from the Roman Senate, and required that the censors be in agreement to exact this punishment. This law, however, was repealed in the third consulship of Pompey in 52 BC, on the urging of his colleague Q. Caecilius Metellus Scipio, but the office of the censorship never recovered its former power and influence.
During the civil wars which followed soon afterwards, no censors were elected; it was only after a long interval that they were again appointed, namely in 23 BC, when Augustus caused Lucius Munatius Plancus and Aemilius Lepidus Paullus to fill the office. This was the last time that such magistrates were appointed; the emperors in future discharged the duties of their office under the name of Praefectura Morum ("prefect of the morals").
Some of the emperors sometimes took the name of censor when they held a census of the Roman people; this was the case with Claudius, who appointed the elder Lucius Vitellius as his colleague, and with Vespasian, who likewise had a colleague in his son Titus. Domitian assumed the title of "perpetual censor" (censor perpetuus), but this example was not imitated by succeeding emperors. In the reign of Decius, the elder Valerian was nominated to the censorship, but declined the position.
The duties of the censors may be divided into three classes, all of which were closely connected with one another:
The original business of the censorship was at first of a much more limited kind, and was restricted almost entirely to taking the census, but the possession of this power gradually brought with it fresh power and new duties, as is shown below. A general view of these duties is briefly expressed in the following passage of Cicero: "Censores populi aevitates, soboles, familias pecuniasque censento: urbis templa, vias, aquas, aerarium, vectigalia tuento: populique partes in tribus distribunto: exin pecunias, aevitates, ordines patiunto: equitum, peditumque prolem describunto: caelibes esse prohibento: mores populi regunto: probrum in senatu ne relinquunto." This can be translated as: "The Censors are to determine the generations, origins, families, and properties of the people; they are to (watch over/protect) the city's temples, roads, waters, treasury, and taxes; they are to divide the people into three parts; next, they are to (allow/approve) the properties, generations, and ranks [of the people]; they are to describe the offspring of knights and footsoldiers; they are to forbid being unmarried; they are to guide the behavior of the people; they are not to overlook abuse in the Senate."
The Census, the first and principal duty of the censors, was always held in the Campus Martius, and from the year 435 BC onwards, in a special building called Villa publica, which was erected for that purpose by the second pair of censors, Gaius Furius Pacilus Fusus and Marcus Geganius Macerinus. An account of the formalities with which the census was opened is given in a fragment of the Tabulae Censoriae, preserved by Varro. After the auspices had been taken, the citizens were summoned by a public crier to appear before the censors. Each tribe was called up separately, and the names in each tribe were probably taken according to the lists previously made out by the tribunes of the tribes. Every pater familias had to appear in person before the censors, who were seated in their curule chairs, and those names were taken first which were considered to be of good omen, such as Valerius, Salvius, Statorius, etc.
The Census was conducted according to the judgement of the censor (ad arbitrium censoris), but the censors laid down certain rules, sometimes called leges censui censendo, in which mention was made of the different kinds of property subject to the census, and in what way their value was to be estimated. According to these laws, each citizen had to give an account of himself, of his family, and of his property upon oath, "declared from the heart". First he had to give his full name (praenomen, nomen, and cognomen) and that of his father, or if he were a libertus ("freedman") that of his patron, and he was likewise obliged to state his age. He was then asked, "You, declaring from your heart, do you have a wife?" and if married he had to give the name of his wife, and likewise the number, names, and ages of his children, if any. Single women and orphans were represented by their guardians; their names were entered in separate lists, and they were not included in the sum total of heads.
After a citizen had stated his name, age, family, etc., he then had to give an account of all his property, so far as it was subject to the census. Only such things were liable to the census (censui censendo) as were property according to the Quiritarian law. At first, each citizen appears to have merely given the value of his whole property in general without entering into details; but it soon became the practice to give a minute specification of each article, as well as the general value of the whole. Land formed the most important article of the census, but public land, the possession of which only belonged to a citizen, was excluded as not being Quiritarian property. Judging from the practice of the imperial period, it was the custom to give a most minute specification of all such land as a citizen held according to the Quiritarian law. He had to state the name and location of the land, and to specify what portion of it was arable, what meadow, what vineyard, and what olive-ground: and of the land thus described, he had to give his assessment of its value.
Slaves and cattle formed the next most important item. The censors also possessed the right of calling for a return of such objects as had not usually been given in, such as clothing, jewels, and carriages. It has been doubted by some modern writers whether the censors possessed the power of setting a higher valuation on the property than the citizens themselves gave, but given the discretionary nature of the censors' powers, and the necessity almost that existed, in order to prevent fraud, that the right of making a surcharge should be vested in somebody's hands, it is likely that the censors had this power. It is moreover expressly stated that on one occasion they made an extravagant surcharge on articles of luxury; and even if they did not enter in their books the property of a person at a higher value than he returned it, they accomplished the same end by compelling him to pay a tax upon the property at a higher rate than others. The tax was usually one per thousand upon the property entered in the books of the censors, but on one occasion the censors compelled a person to pay eight per thousand as a punishment.
A person who voluntarily absented himself from the census was considered incensus and subject to the severest punishment. Servius Tullius is said to have threatened such individuals with imprisonment and death, and in the Republican period he might be sold by the state as a slave. In the later period of the Republic, a person who was absent from the census might be represented by another, and be thus registered by the censors. Whether the soldiers who were absent on service had to appoint a representative is uncertain. In ancient times, the sudden outbreaks of war prevented the census from being taken, because a large number of the citizens would necessarily be absent. It is supposed from a passage in Livy that in later times the censors sent commissioners into the provinces with full powers to take the census of the Roman soldiers there, but this seems to have been a special case. It is, on the contrary, probable from the way in which Cicero pleads the absence of Archias from Rome with the army under Lucullus, as a sufficient reason for his not having been enrolled in the census, that service in the army was a valid excuse for absence.
After the censors had received the names of all the citizens with the amount of their property, they then had to make out the lists of the tribes, and also of the classes and centuries; for by the legislation of Servius Tullius the position of each citizen in the state was determined by the amount of his property (Comitia Centuriata). These lists formed a most important part of the Tabulae Censoriae, under which name were included all the documents connected in any way with the discharge of the censors' duties. These lists, insofar as they were connected with the finances of the state, were deposited in the aerarium, located in the Temple of Saturn; but the regular depository for all the archives of the censors was in earlier times the Atrium Libertatis, near the Villa publica, and in later times the temple of the Nymphs.
Besides the division of the citizens into tribes, centuries, and classes, the censors had also to make out the lists of the senators for the ensuing five years, or until new censors were appointed, striking out the names of such as they considered unworthy, and making additions to the body from those who were qualified. In the same manner they held a review of the equites who received a horse from public funds (equites equo publico), and added and removed names as they judged proper. They also confirmed the princeps senatus, or appointed a new one. The princeps himself had to be a former censor. After the lists had been completed, the number of citizens was counted up, and the sum total announced. Accordingly, we find that in the account of a census, the number of citizens is likewise usually given. They are in such cases spoken of as capita ("heads"), sometimes with the addition of the word civium ("of the citizens"), and sometimes not. Hence, to be registered in the census was the same thing as "having a head" (caput habere).
A census was sometimes taken in the provinces, even under the Republic. The emperor sent into the provinces special officers called censitores to take the census; but the duty was sometimes discharged by the Imperial legati. The censitores were assisted by subordinate officers, called censuales, who made out the lists, etc. In Rome, the census was still taken under the Empire, but the old ceremonies connected with it were no longer performed, and the ceremony of the lustratio was not performed after the time of Vespasian. The jurists Paulus and Ulpian each wrote works on the census in the imperial period; and several extracts from these works are given in a chapter in the Digest (50 15).
The word census, besides the conventional meaning of "valuation" of a person's estate, has other meaning in Rome; it could refer to:
Keeping the public morals (regimen morum, or in the Empire cura morum or praefectura morum) was the second most important branch of the censors' duties, and the one which caused their office to be one of the most revered and the most dreaded; hence they were also known as castigatores ("chastisers"). It naturally grew out of the right which they possessed of excluding persons from the lists of citizens; for, as has been well remarked, "they would, in the first place, be the sole judges of many questions of fact, such as whether a citizen had the qualifications required by law or custom for the rank which he claimed, or whether he had ever incurred any judicial sentence, which rendered him infamous: but from thence the transition was easy, according to Roman notions, to the decisions of questions of right; such as whether a citizen was really worthy of retaining his rank, whether he had not committed some act as justly degrading as those which incurred the sentence of the law."
In this manner, the censors gradually assumed at least nominal complete superintendence over the whole public and private life of every citizen. They were constituted as the conservators of public morality; they were not simply to prevent crime or particular acts of immorality, but rather to maintain the traditional Roman character, ethics, and habits (mos majorum)—regimen morum also encompassed this protection of traditional ways, which was called in the times of the Empire cura ("supervision") or praefectura ("command"). The punishment inflicted by the censors in the exercise of this branch of their duties was called nota ("mark, letter") or notatio, or animadversio censoria ("censorial reproach"). In inflicting it, they were guided only by their conscientious convictions of duty; they had to take an oath that they would act biased by neither partiality nor favour; and, in addition to this, they were bound in every case to state in their lists, opposite the name of the guilty citizen, the cause of the punishment inflicted on him, subscriptio censoria.
This part of the censors' office invested them with a peculiar kind of jurisdiction, which in many respects resembled the exercise of public opinion in modern times; for there are innumerable actions which, though acknowledged by everyone to be prejudicial and immoral, still do not come within the reach of the positive laws of a country; as often said, "immorality does not equal illegality". Even in cases of real crimes, the positive laws frequently punish only the particular offence, while in public opinion the offender, even after he has undergone punishment, is still incapacitated for certain honours and distinctions which are granted only to persons of unblemished character.
Hence, the Roman censors might brand a man with their "censorial mark" (nota censoria) in case he had been convicted of a crime in an ordinary court of justice, and had already suffered punishment for it. The consequence of such a nota was only ignominia and not infamia. Infamia and the censorial verdict was not a judicium or res judicata, for its effects were not lasting, but might be removed by the following censors, or by a lex (roughly "law"). A censorial mark was moreover not valid unless both censors agreed. The ignominia was thus only a transitory reduction of status, which does not even appear to have deprived a magistrate of his office, and certainly did not disqualify persons labouring under it for obtaining a magistracy, for being appointed as judices by the praetor, or for serving in the Roman army. Mamercus Aemilius Mamercinus was thus, notwithstanding the reproach of the censors (animadversio censoria), made dictator.
A person might be branded with a censorial mark in a variety of cases, which it would be impossible to specify, as in a great many instances it depended upon the discretion of the censors and the view they took of a case; and sometimes even one set of censors would overlook an offence which was severely chastised by their successors. But the offences which are recorded to have been punished by the censors are of a threefold nature.
A person who had been branded with a nota censoria, might, if he considered himself wronged, endeavour to prove his innocence to the censors, and if he did not succeed, he might try to gain the protection of one of the censors, that he might intercede on his behalf.
The punishments inflicted by the censors generally differed according to the station which a man occupied, though sometimes a person of the highest rank might suffer all the punishments at once, by being degraded to the lowest class of citizens. The punishments are generally divided into four classes:
It was this authority of the Roman censors which eventually developed into the modern meaning of "censor" and "censorship"—i.e., officials who review published material and forbid the publication of material judged to be contrary to "public morality" as the term is interpreted in a given political and social environment.
The administration of the state's finances was another part of the censors' office. In the first place the tributum, or property-tax, had to be paid by each citizen according to the amount of his property registered in the census, and, accordingly, the regulation of this tax naturally fell under the jurisdiction of the censors. They also had the superintendence of all the other revenues of the state, the vectigalia, such as the tithes paid for the public lands, the salt works, the mines, the customs, etc.
The censors typically auctioned off to the highest bidder for the space of a lustrum the collection of the tithes and taxes (tax farming). This auctioning was called venditio or locatio, and seems to have taken place in the month of March, in a public place in Rome The terms on which they were let, together with the rights and duties of the purchasers, were all specified in the leges censoriae, which the censors published in every case before the bidding commenced. For further particulars see Publicani.
The censors also possessed the right, though probably not without the assent of the Senate, of imposing new vectigalia, and even of selling the land belonging to the state. It would thus appear that it was the duty of the censors to bring forward a budget for a five-year period, and to take care that the income of the state was sufficient for its expenditure during that time. In part, their duties resembled those of a modern minister of finance. The censors, however, did not receive the revenues of the state. All the public money was paid into the aerarium, which was entirely under the jurisdiction of the Senate; and all disbursements were made by order of this body, which employed the quaestors as its officers.
In one important department, the public works, the censors were entrusted with the expenditure of the public money (though the actual payments were no doubt made by the quaestors).
The censors had the general superintendence of all the public buildings and works (opera publica), and to meet the expenses connected with this part of their duties, the Senate voted them a certain sum of money or certain revenues, to which they were restricted, but which they might at the same time employ according to their discretion. They had to see that the temples and all other public buildings were in a good state of repair, that no public places were encroached upon by the occupation of private persons, and that the aqueducts, roads, drains, etc. were properly attended to.
The repairs of the public works and the keeping of them in proper condition were let out by the censors by public auction to the lowest bidder, just as the vectigalia were let out to the highest bidder. These expenses were called ultrotributa, and hence we frequently find vectigalia and ultrotributa contrasted with one another. The persons who undertook the contract were called conductores, mancipes, redemptores, susceptores, etc., and the duties they had to discharge were specified in the Leges Censoriae. The censors had also to superintend the expenses connected with the worship of the gods, even for instance the feeding of the sacred geese in the Capitol; these various tasks were also let out on contract. It was ordinary for censors to expend large amounts of money (“by far the largest and most extensive” of the state) in their public works.
Besides keeping existing public buildings and facilities in a proper state of repair, the censors were also in charge of constructing new ones, either for ornament or utility, both in Rome and in other parts of Italy, such as temples, basilicae, theatres, porticoes, fora, aqueducts, town walls, harbours, bridges, cloacae, roads, etc. These works were either performed by them jointly, or they divided between them the money, which had been granted to them by the Senate. They were let out to contractors, like the other works mentioned above, and when they were completed, the censors had to see that the work was performed in accordance with the contract: this was called opus probare or in acceptum referre.
The first ever Roman road, the Via Appia, and the first Roman aqueduct, the Aqua Appia, were all constructed under the censorship of Appius Claudius Caecus, one of the most influential censors.
The aediles had likewise a superintendence over the public buildings, and it is not easy to define with accuracy the respective duties of the censors and aediles, but it may be remarked in general that the superintendence of the aediles had more of a police character, while that of the censors were more financial in subject matter.
After the censors had performed their various duties and taken the five-yearly census, the lustrum, a solemn purification of the people, followed. When the censors entered upon their office, they drew lots to see which of them should perform this purification; but both censors were of course obliged to be present at the ceremony.
Long after the Roman census was no longer taken, the Latin word lustrum has survived, and been adopted in some modern languages, in the derived sense of a period of five years, i.e., half a decennium. | [
{
"paragraph_id": 0,
"text": "The censor was a magistrate in ancient Rome who was responsible for maintaining the census, supervising public morality, and overseeing certain aspects of the government's finances.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The power of the censor was absolute: no magistrate could oppose his decisions, and only another censor who succeeded him could cancel those decisions.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The censor's regulation of public morality is the origin of the modern meaning of the words censor and censorship.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The census was first instituted by Servius Tullius, sixth king of Rome, c. 575–535 BC. After the abolition of the monarchy and the founding of the Republic in 509 BC, the consuls had responsibility for the census until 443 BC. In 442 BC, no consuls were elected, but tribunes with consular power were appointed instead. This was a move by the plebeians to try to attain higher magistracies: only patricians could be elected consuls, while some military tribunes were plebeians. To prevent the possibility of plebeians obtaining control of the census, the patricians removed the right to take the census from the consuls and tribunes, and appointed for this duty two magistrates, called censores (censors), elected exclusively from the patricians in Rome.",
"title": "Early history of the magistracy"
},
{
"paragraph_id": 4,
"text": "The magistracy continued to be controlled by patricians until 351 BC, when Gaius Marcius Rutilus was appointed the first plebeian censor. Twelve years later, in 339 BC, one of the Publilian laws required that one censor had to be a plebeian. Despite this, no plebeian censor performed the solemn purification of the people (the lustrum; Livy Periochae 13) until 280 BC. In 131 BC, for the first time, both censors were plebeians.",
"title": "Early history of the magistracy"
},
{
"paragraph_id": 5,
"text": "The reason for having two censors was that the two consuls had previously taken the census together. If one of the censors died during his term of office, another was chosen to replace him, just as with consuls. This happened only once, in 393 BC. However, the Gauls captured Rome in that lustrum (five-year period), and the Romans thereafter regarded such replacement as \"an offense against religion\". From then on, if one of the censors died, his colleague resigned, and two new censors were chosen to replace them.",
"title": "Early history of the magistracy"
},
{
"paragraph_id": 6,
"text": "The office of censor was limited to eighteen months by a law proposed by the dictator Mamercus Aemilius Mamercinus. During the censorship of Appius Claudius Caecus (312–308 BC) the prestige of the censorship massively increased. Caecus built the first-ever Roman road (the Via Appia) and the first Roman aqueduct (the Aqua Appia), both named after him. He changed the organisation of the Roman tribes and was the first censor to draw the list of senators. He also advocated the founding of Roman coloniae throughout Latium and Campania to support the Roman war effort in the Second Samnite War. With these efforts and reforms, Appius Claudius Caecus was able to hold the censorship for a whole lustrum (five-year period), and the office of censor, subsequently entrusted with various important duties, eventually attained one of the highest political statuses in the Roman Republic, second only to that of the consuls.",
"title": "Early history of the magistracy"
},
{
"paragraph_id": 7,
"text": "The censors were elected in the Centuriate Assembly, which met under the presidency of a consul. Barthold Niebuhr suggests that the censors were at first elected by the Curiate Assembly, and that the Assembly's selections were confirmed by the Centuriate, but William Smith believes that \"there is no authority for this supposition, and the truth of it depends entirely upon the correctness of [Niebuhr's] views respecting the election of the consuls\". Both censors had to be elected on the same day, and accordingly if the voting for the second was not finished in the same day, the election of the first was invalidated, and a new assembly had to be held.",
"title": "Election"
},
{
"paragraph_id": 8,
"text": "The assembly for the election of the censors was held under different auspices from those at the election of the consuls and praetors, so the censors were not regarded as their colleagues, although they likewise possessed the maxima auspicia. The assembly was held by the new consuls shortly after they began their term of office; and the censors, as soon as they were elected and the censorial power had been granted to them by a decree of the Centuriate Assembly (lex centuriata), were fully installed in their office.",
"title": "Election"
},
{
"paragraph_id": 9,
"text": "As a general principle, the only ones eligible for the office of censor were those who had previously been consuls, but there were a few exceptions. At first, there was no law to prevent a person being censor twice, but the only person who was elected to the office twice was Gaius Marcius Rutilus in 265 BC. In that year, he originated a law stating that no one could be elected censor twice. In consequence of this, he received the cognomen of Censorinus.",
"title": "Election"
},
{
"paragraph_id": 10,
"text": "The censorship differed from all other Roman magistracies in the length of office. The censors were originally chosen for a whole lustrum (a period of five years), but as early as ten years after its institution (433 BC) their office was limited to eighteen months by a law of Dictator Mamercus Aemilius Mamercinus. The censors were also unique with respect to rank and dignity. They had no imperium, and accordingly no lictors. Their rank was granted to them by the Centuriate Assembly, and not by the curiae, and in that respect they were inferior in power to the consuls and praetors.",
"title": "Attributes"
},
{
"paragraph_id": 11,
"text": "Notwithstanding this, the censorship was regarded as the highest dignity in the state, with the exception of the dictatorship; it was a \"sacred magistracy\" (sanctus magistratus), to which the deepest reverence was due. The high rank and dignity which the censorship obtained was due to the various important duties gradually entrusted to it, and especially to its possessing the regimen morum, or general control over the conduct and the morals of the citizens. In the exercise of this power, they were regulated solely by their own views of duty, and were not responsible to any other power in the state.",
"title": "Attributes"
},
{
"paragraph_id": 12,
"text": "The censors possessed the official stool called a \"curule chair\" (sella curulis), but some doubt exists with respect to their official dress. A well-known passage of Polybius describes the use of the imagines at funerals; we may conclude that a consul or praetor wore the purple-bordered toga praetexta, one who triumphed the embroidered toga picta, and the censor a purple toga peculiar to him, but other writers speak of their official dress as being the same as that of the other higher magistrates. The funeral of a censor was always conducted with great pomp and splendour, and hence a \"censorial funeral\" (funus censorium) was voted even to the emperors.",
"title": "Attributes"
},
{
"paragraph_id": 13,
"text": "The censorship continued in existence for 421 years, from 443 BC to 22 BC, but during this period, many lustra passed by without any censor being chosen at all. According to one statement, the office was abolished by Lucius Cornelius Sulla. Although the authority on which this statement rests is not of much weight, the fact itself is probable, since there was no census during the two lustra which elapsed from Sulla's dictatorship to Gnaeus Pompeius Magnus (Pompey)'s first consulship (82–70 BC), and any strict \"imposition of morals\" would have been found inconvenient to the aristocracy that supported Sulla.",
"title": "Abolition"
},
{
"paragraph_id": 14,
"text": "If the censorship had been done away with by Sulla, it was at any rate restored in the consulship of Pompey and Marcus Licinius Crassus. Its power was limited by one of the laws of the tribune Publius Clodius Pulcher (58 BC), which prescribed certain regular forms of proceeding before the censors in expelling a person from the Roman Senate, and required that the censors be in agreement to exact this punishment. This law, however, was repealed in the third consulship of Pompey in 52 BC, on the urging of his colleague Q. Caecilius Metellus Scipio, but the office of the censorship never recovered its former power and influence.",
"title": "Abolition"
},
{
"paragraph_id": 15,
"text": "During the civil wars which followed soon afterwards, no censors were elected; it was only after a long interval that they were again appointed, namely in 23 BC, when Augustus caused Lucius Munatius Plancus and Aemilius Lepidus Paullus to fill the office. This was the last time that such magistrates were appointed; the emperors in future discharged the duties of their office under the name of Praefectura Morum (\"prefect of the morals\").",
"title": "Abolition"
},
{
"paragraph_id": 16,
"text": "Some of the emperors sometimes took the name of censor when they held a census of the Roman people; this was the case with Claudius, who appointed the elder Lucius Vitellius as his colleague, and with Vespasian, who likewise had a colleague in his son Titus. Domitian assumed the title of \"perpetual censor\" (censor perpetuus), but this example was not imitated by succeeding emperors. In the reign of Decius, the elder Valerian was nominated to the censorship, but declined the position.",
"title": "Abolition"
},
{
"paragraph_id": 17,
"text": "The duties of the censors may be divided into three classes, all of which were closely connected with one another:",
"title": "Duties"
},
{
"paragraph_id": 18,
"text": "The original business of the censorship was at first of a much more limited kind, and was restricted almost entirely to taking the census, but the possession of this power gradually brought with it fresh power and new duties, as is shown below. A general view of these duties is briefly expressed in the following passage of Cicero: \"Censores populi aevitates, soboles, familias pecuniasque censento: urbis templa, vias, aquas, aerarium, vectigalia tuento: populique partes in tribus distribunto: exin pecunias, aevitates, ordines patiunto: equitum, peditumque prolem describunto: caelibes esse prohibento: mores populi regunto: probrum in senatu ne relinquunto.\" This can be translated as: \"The Censors are to determine the generations, origins, families, and properties of the people; they are to (watch over/protect) the city's temples, roads, waters, treasury, and taxes; they are to divide the people into three parts; next, they are to (allow/approve) the properties, generations, and ranks [of the people]; they are to describe the offspring of knights and footsoldiers; they are to forbid being unmarried; they are to guide the behavior of the people; they are not to overlook abuse in the Senate.\"",
"title": "Duties"
},
{
"paragraph_id": 19,
"text": "The Census, the first and principal duty of the censors, was always held in the Campus Martius, and from the year 435 BC onwards, in a special building called Villa publica, which was erected for that purpose by the second pair of censors, Gaius Furius Pacilus Fusus and Marcus Geganius Macerinus. An account of the formalities with which the census was opened is given in a fragment of the Tabulae Censoriae, preserved by Varro. After the auspices had been taken, the citizens were summoned by a public crier to appear before the censors. Each tribe was called up separately, and the names in each tribe were probably taken according to the lists previously made out by the tribunes of the tribes. Every pater familias had to appear in person before the censors, who were seated in their curule chairs, and those names were taken first which were considered to be of good omen, such as Valerius, Salvius, Statorius, etc.",
"title": "Duties"
},
{
"paragraph_id": 20,
"text": "The Census was conducted according to the judgement of the censor (ad arbitrium censoris), but the censors laid down certain rules, sometimes called leges censui censendo, in which mention was made of the different kinds of property subject to the census, and in what way their value was to be estimated. According to these laws, each citizen had to give an account of himself, of his family, and of his property upon oath, \"declared from the heart\". First he had to give his full name (praenomen, nomen, and cognomen) and that of his father, or if he were a libertus (\"freedman\") that of his patron, and he was likewise obliged to state his age. He was then asked, \"You, declaring from your heart, do you have a wife?\" and if married he had to give the name of his wife, and likewise the number, names, and ages of his children, if any. Single women and orphans were represented by their guardians; their names were entered in separate lists, and they were not included in the sum total of heads.",
"title": "Duties"
},
{
"paragraph_id": 21,
"text": "After a citizen had stated his name, age, family, etc., he then had to give an account of all his property, so far as it was subject to the census. Only such things were liable to the census (censui censendo) as were property according to the Quiritarian law. At first, each citizen appears to have merely given the value of his whole property in general without entering into details; but it soon became the practice to give a minute specification of each article, as well as the general value of the whole. Land formed the most important article of the census, but public land, the possession of which only belonged to a citizen, was excluded as not being Quiritarian property. Judging from the practice of the imperial period, it was the custom to give a most minute specification of all such land as a citizen held according to the Quiritarian law. He had to state the name and location of the land, and to specify what portion of it was arable, what meadow, what vineyard, and what olive-ground: and of the land thus described, he had to give his assessment of its value.",
"title": "Duties"
},
{
"paragraph_id": 22,
"text": "Slaves and cattle formed the next most important item. The censors also possessed the right of calling for a return of such objects as had not usually been given in, such as clothing, jewels, and carriages. It has been doubted by some modern writers whether the censors possessed the power of setting a higher valuation on the property than the citizens themselves gave, but given the discretionary nature of the censors' powers, and the necessity almost that existed, in order to prevent fraud, that the right of making a surcharge should be vested in somebody's hands, it is likely that the censors had this power. It is moreover expressly stated that on one occasion they made an extravagant surcharge on articles of luxury; and even if they did not enter in their books the property of a person at a higher value than he returned it, they accomplished the same end by compelling him to pay a tax upon the property at a higher rate than others. The tax was usually one per thousand upon the property entered in the books of the censors, but on one occasion the censors compelled a person to pay eight per thousand as a punishment.",
"title": "Duties"
},
{
"paragraph_id": 23,
"text": "A person who voluntarily absented himself from the census was considered incensus and subject to the severest punishment. Servius Tullius is said to have threatened such individuals with imprisonment and death, and in the Republican period he might be sold by the state as a slave. In the later period of the Republic, a person who was absent from the census might be represented by another, and be thus registered by the censors. Whether the soldiers who were absent on service had to appoint a representative is uncertain. In ancient times, the sudden outbreaks of war prevented the census from being taken, because a large number of the citizens would necessarily be absent. It is supposed from a passage in Livy that in later times the censors sent commissioners into the provinces with full powers to take the census of the Roman soldiers there, but this seems to have been a special case. It is, on the contrary, probable from the way in which Cicero pleads the absence of Archias from Rome with the army under Lucullus, as a sufficient reason for his not having been enrolled in the census, that service in the army was a valid excuse for absence.",
"title": "Duties"
},
{
"paragraph_id": 24,
"text": "After the censors had received the names of all the citizens with the amount of their property, they then had to make out the lists of the tribes, and also of the classes and centuries; for by the legislation of Servius Tullius the position of each citizen in the state was determined by the amount of his property (Comitia Centuriata). These lists formed a most important part of the Tabulae Censoriae, under which name were included all the documents connected in any way with the discharge of the censors' duties. These lists, insofar as they were connected with the finances of the state, were deposited in the aerarium, located in the Temple of Saturn; but the regular depository for all the archives of the censors was in earlier times the Atrium Libertatis, near the Villa publica, and in later times the temple of the Nymphs.",
"title": "Duties"
},
{
"paragraph_id": 25,
"text": "Besides the division of the citizens into tribes, centuries, and classes, the censors had also to make out the lists of the senators for the ensuing five years, or until new censors were appointed, striking out the names of such as they considered unworthy, and making additions to the body from those who were qualified. In the same manner they held a review of the equites who received a horse from public funds (equites equo publico), and added and removed names as they judged proper. They also confirmed the princeps senatus, or appointed a new one. The princeps himself had to be a former censor. After the lists had been completed, the number of citizens was counted up, and the sum total announced. Accordingly, we find that in the account of a census, the number of citizens is likewise usually given. They are in such cases spoken of as capita (\"heads\"), sometimes with the addition of the word civium (\"of the citizens\"), and sometimes not. Hence, to be registered in the census was the same thing as \"having a head\" (caput habere).",
"title": "Duties"
},
{
"paragraph_id": 26,
"text": "A census was sometimes taken in the provinces, even under the Republic. The emperor sent into the provinces special officers called censitores to take the census; but the duty was sometimes discharged by the Imperial legati. The censitores were assisted by subordinate officers, called censuales, who made out the lists, etc. In Rome, the census was still taken under the Empire, but the old ceremonies connected with it were no longer performed, and the ceremony of the lustratio was not performed after the time of Vespasian. The jurists Paulus and Ulpian each wrote works on the census in the imperial period; and several extracts from these works are given in a chapter in the Digest (50 15).",
"title": "Duties"
},
{
"paragraph_id": 27,
"text": "The word census, besides the conventional meaning of \"valuation\" of a person's estate, has other meaning in Rome; it could refer to:",
"title": "Duties"
},
{
"paragraph_id": 28,
"text": "Keeping the public morals (regimen morum, or in the Empire cura morum or praefectura morum) was the second most important branch of the censors' duties, and the one which caused their office to be one of the most revered and the most dreaded; hence they were also known as castigatores (\"chastisers\"). It naturally grew out of the right which they possessed of excluding persons from the lists of citizens; for, as has been well remarked, \"they would, in the first place, be the sole judges of many questions of fact, such as whether a citizen had the qualifications required by law or custom for the rank which he claimed, or whether he had ever incurred any judicial sentence, which rendered him infamous: but from thence the transition was easy, according to Roman notions, to the decisions of questions of right; such as whether a citizen was really worthy of retaining his rank, whether he had not committed some act as justly degrading as those which incurred the sentence of the law.\"",
"title": "Duties"
},
{
"paragraph_id": 29,
"text": "In this manner, the censors gradually assumed at least nominal complete superintendence over the whole public and private life of every citizen. They were constituted as the conservators of public morality; they were not simply to prevent crime or particular acts of immorality, but rather to maintain the traditional Roman character, ethics, and habits (mos majorum)—regimen morum also encompassed this protection of traditional ways, which was called in the times of the Empire cura (\"supervision\") or praefectura (\"command\"). The punishment inflicted by the censors in the exercise of this branch of their duties was called nota (\"mark, letter\") or notatio, or animadversio censoria (\"censorial reproach\"). In inflicting it, they were guided only by their conscientious convictions of duty; they had to take an oath that they would act biased by neither partiality nor favour; and, in addition to this, they were bound in every case to state in their lists, opposite the name of the guilty citizen, the cause of the punishment inflicted on him, subscriptio censoria.",
"title": "Duties"
},
{
"paragraph_id": 30,
"text": "This part of the censors' office invested them with a peculiar kind of jurisdiction, which in many respects resembled the exercise of public opinion in modern times; for there are innumerable actions which, though acknowledged by everyone to be prejudicial and immoral, still do not come within the reach of the positive laws of a country; as often said, \"immorality does not equal illegality\". Even in cases of real crimes, the positive laws frequently punish only the particular offence, while in public opinion the offender, even after he has undergone punishment, is still incapacitated for certain honours and distinctions which are granted only to persons of unblemished character.",
"title": "Duties"
},
{
"paragraph_id": 31,
"text": "Hence, the Roman censors might brand a man with their \"censorial mark\" (nota censoria) in case he had been convicted of a crime in an ordinary court of justice, and had already suffered punishment for it. The consequence of such a nota was only ignominia and not infamia. Infamia and the censorial verdict was not a judicium or res judicata, for its effects were not lasting, but might be removed by the following censors, or by a lex (roughly \"law\"). A censorial mark was moreover not valid unless both censors agreed. The ignominia was thus only a transitory reduction of status, which does not even appear to have deprived a magistrate of his office, and certainly did not disqualify persons labouring under it for obtaining a magistracy, for being appointed as judices by the praetor, or for serving in the Roman army. Mamercus Aemilius Mamercinus was thus, notwithstanding the reproach of the censors (animadversio censoria), made dictator.",
"title": "Duties"
},
{
"paragraph_id": 32,
"text": "A person might be branded with a censorial mark in a variety of cases, which it would be impossible to specify, as in a great many instances it depended upon the discretion of the censors and the view they took of a case; and sometimes even one set of censors would overlook an offence which was severely chastised by their successors. But the offences which are recorded to have been punished by the censors are of a threefold nature.",
"title": "Duties"
},
{
"paragraph_id": 33,
"text": "A person who had been branded with a nota censoria, might, if he considered himself wronged, endeavour to prove his innocence to the censors, and if he did not succeed, he might try to gain the protection of one of the censors, that he might intercede on his behalf.",
"title": "Duties"
},
{
"paragraph_id": 34,
"text": "The punishments inflicted by the censors generally differed according to the station which a man occupied, though sometimes a person of the highest rank might suffer all the punishments at once, by being degraded to the lowest class of citizens. The punishments are generally divided into four classes:",
"title": "Duties"
},
{
"paragraph_id": 35,
"text": "It was this authority of the Roman censors which eventually developed into the modern meaning of \"censor\" and \"censorship\"—i.e., officials who review published material and forbid the publication of material judged to be contrary to \"public morality\" as the term is interpreted in a given political and social environment.",
"title": "Duties"
},
{
"paragraph_id": 36,
"text": "The administration of the state's finances was another part of the censors' office. In the first place the tributum, or property-tax, had to be paid by each citizen according to the amount of his property registered in the census, and, accordingly, the regulation of this tax naturally fell under the jurisdiction of the censors. They also had the superintendence of all the other revenues of the state, the vectigalia, such as the tithes paid for the public lands, the salt works, the mines, the customs, etc.",
"title": "Duties"
},
{
"paragraph_id": 37,
"text": "The censors typically auctioned off to the highest bidder for the space of a lustrum the collection of the tithes and taxes (tax farming). This auctioning was called venditio or locatio, and seems to have taken place in the month of March, in a public place in Rome The terms on which they were let, together with the rights and duties of the purchasers, were all specified in the leges censoriae, which the censors published in every case before the bidding commenced. For further particulars see Publicani.",
"title": "Duties"
},
{
"paragraph_id": 38,
"text": "The censors also possessed the right, though probably not without the assent of the Senate, of imposing new vectigalia, and even of selling the land belonging to the state. It would thus appear that it was the duty of the censors to bring forward a budget for a five-year period, and to take care that the income of the state was sufficient for its expenditure during that time. In part, their duties resembled those of a modern minister of finance. The censors, however, did not receive the revenues of the state. All the public money was paid into the aerarium, which was entirely under the jurisdiction of the Senate; and all disbursements were made by order of this body, which employed the quaestors as its officers.",
"title": "Duties"
},
{
"paragraph_id": 39,
"text": "In one important department, the public works, the censors were entrusted with the expenditure of the public money (though the actual payments were no doubt made by the quaestors).",
"title": "Duties"
},
{
"paragraph_id": 40,
"text": "The censors had the general superintendence of all the public buildings and works (opera publica), and to meet the expenses connected with this part of their duties, the Senate voted them a certain sum of money or certain revenues, to which they were restricted, but which they might at the same time employ according to their discretion. They had to see that the temples and all other public buildings were in a good state of repair, that no public places were encroached upon by the occupation of private persons, and that the aqueducts, roads, drains, etc. were properly attended to.",
"title": "Duties"
},
{
"paragraph_id": 41,
"text": "The repairs of the public works and the keeping of them in proper condition were let out by the censors by public auction to the lowest bidder, just as the vectigalia were let out to the highest bidder. These expenses were called ultrotributa, and hence we frequently find vectigalia and ultrotributa contrasted with one another. The persons who undertook the contract were called conductores, mancipes, redemptores, susceptores, etc., and the duties they had to discharge were specified in the Leges Censoriae. The censors had also to superintend the expenses connected with the worship of the gods, even for instance the feeding of the sacred geese in the Capitol; these various tasks were also let out on contract. It was ordinary for censors to expend large amounts of money (“by far the largest and most extensive” of the state) in their public works.",
"title": "Duties"
},
{
"paragraph_id": 42,
"text": "Besides keeping existing public buildings and facilities in a proper state of repair, the censors were also in charge of constructing new ones, either for ornament or utility, both in Rome and in other parts of Italy, such as temples, basilicae, theatres, porticoes, fora, aqueducts, town walls, harbours, bridges, cloacae, roads, etc. These works were either performed by them jointly, or they divided between them the money, which had been granted to them by the Senate. They were let out to contractors, like the other works mentioned above, and when they were completed, the censors had to see that the work was performed in accordance with the contract: this was called opus probare or in acceptum referre.",
"title": "Duties"
},
{
"paragraph_id": 43,
"text": "The first ever Roman road, the Via Appia, and the first Roman aqueduct, the Aqua Appia, were all constructed under the censorship of Appius Claudius Caecus, one of the most influential censors.",
"title": "Duties"
},
{
"paragraph_id": 44,
"text": "The aediles had likewise a superintendence over the public buildings, and it is not easy to define with accuracy the respective duties of the censors and aediles, but it may be remarked in general that the superintendence of the aediles had more of a police character, while that of the censors were more financial in subject matter.",
"title": "Duties"
},
{
"paragraph_id": 45,
"text": "After the censors had performed their various duties and taken the five-yearly census, the lustrum, a solemn purification of the people, followed. When the censors entered upon their office, they drew lots to see which of them should perform this purification; but both censors were of course obliged to be present at the ceremony.",
"title": "Duties"
},
{
"paragraph_id": 46,
"text": "Long after the Roman census was no longer taken, the Latin word lustrum has survived, and been adopted in some modern languages, in the derived sense of a period of five years, i.e., half a decennium.",
"title": "Duties"
}
] | The censor was a magistrate in ancient Rome who was responsible for maintaining the census, supervising public morality, and overseeing certain aspects of the government's finances. The power of the censor was absolute: no magistrate could oppose his decisions, and only another censor who succeeded him could cancel those decisions. The censor's regulation of public morality is the origin of the modern meaning of the words censor and censorship. | 2001-09-07T18:44:23Z | 2023-12-07T02:36:51Z | [
"Template:SmithDGRA",
"Template:-",
"Template:Short description",
"Template:See also",
"Template:Notelist",
"Template:Cite encyclopedia",
"Template:Refbegin",
"Template:Cite journal",
"Template:Circa",
"Template:Cn",
"Template:Ancient Rome topics",
"Template:Politics of Ancient Rome",
"Template:Citation needed",
"Template:Ordered list",
"Template:Reflist",
"Template:Cite web",
"Template:Refend"
] | https://en.wikipedia.org/wiki/Roman_censor |
6,292 | Convex set | In geometry, a subset of a Euclidean space, or more generally an affine space over the reals, is convex if, given any two points in the subset, the subset contains the whole line segment that joins them. Equivalently, a convex set or a convex region is a subset that intersects every line into a single line segment (possibly empty). For example, a solid cube is a convex set, but anything that is hollow or has an indent, for example, a crescent shape, is not convex.
The boundary of a convex set is always a convex curve. The intersection of all the convex sets that contain a given subset A of Euclidean space is called the convex hull of A. It is the smallest convex set containing A.
A convex function is a real-valued function defined on an interval with the property that its epigraph (the set of points on or above the graph of the function) is a convex set. Convex minimization is a subfield of optimization that studies the problem of minimizing convex functions over convex sets. The branch of mathematics devoted to the study of properties of convex sets and convex functions is called convex analysis.
The notion of a convex set can be generalized as described below.
Let S be a vector space or an affine space over the real numbers, or, more generally, over some ordered field (this includes Euclidean spaces, which are affine spaces). A subset C of S is convex if, for all x and y in C, the line segment connecting x and y is included in C.
This means that the affine combination (1 − t)x + ty belongs to C for all x,y in C and t in the interval [0, 1]. This implies that convexity is invariant under affine transformations. Further, it implies that a convex set in a real or complex topological vector space is path-connected (and therefore also connected).
A set C is strictly convex if every point on the line segment connecting x and y other than the endpoints is inside the topological interior of C. A closed convex subset is strictly convex if and only if every one of its boundary points is an extreme point.
A set C is absolutely convex if it is convex and balanced.
The convex subsets of R (the set of real numbers) are the intervals and the points of R. Some examples of convex subsets of the Euclidean plane are solid regular polygons, solid triangles, and intersections of solid triangles. Some examples of convex subsets of a Euclidean 3-dimensional space are the Archimedean solids and the Platonic solids. The Kepler-Poinsot polyhedra are examples of non-convex sets.
A set that is not convex is called a non-convex set. A polygon that is not a convex polygon is sometimes called a concave polygon, and some sources more generally use the term concave set to mean a non-convex set, but most authorities prohibit this usage.
The complement of a convex set, such as the epigraph of a concave function, is sometimes called a reverse convex set, especially in the context of mathematical optimization.
Given r points u1, ..., ur in a convex set S, and r nonnegative numbers λ1, ..., λr such that λ1 + ... + λr = 1, the affine combination
belongs to S. As the definition of a convex set is the case r = 2, this property characterizes convex sets.
Such an affine combination is called a convex combination of u1, ..., ur.
The collection of convex subsets of a vector space, an affine space, or a Euclidean space has the following properties:
Closed convex sets are convex sets that contain all their limit points. They can be characterised as the intersections of closed half-spaces (sets of point in space that lie on and to one side of a hyperplane).
From what has just been said, it is clear that such intersections are convex, and they will also be closed sets. To prove the converse, i.e., every closed convex set may be represented as such intersection, one needs the supporting hyperplane theorem in the form that for a given closed convex set C and point P outside it, there is a closed half-space H that contains C and not P. The supporting hyperplane theorem is a special case of the Hahn–Banach theorem of functional analysis.
Let C be a convex body in the plane (a convex set whose interior is non-empty). We can inscribe a rectangle r in C such that a homothetic copy R of r is circumscribed about C. The positive homothety ratio is at most 2 and:
The set K 2 {\displaystyle {\mathcal {K}}^{2}} of all planar convex bodies can be parameterized in terms of the convex body diameter D, its inradius r (the biggest circle contained in the convex body) and its circumradius R (the smallest circle containing the convex body). In fact, this set can be described by the set of inequalities given by
and can be visualized as the image of the function g that maps a convex body to the R point given by (r/R, D/2R). The image of this function is known a (r, D, R) Blachke-Santaló diagram.
Alternatively, the set K 2 {\displaystyle {\mathcal {K}}^{2}} can also be parametrized by its width (the smallest distance between any two different parallel support hyperplanes), perimeter and area.
Let X be a topological vector space and C ⊆ X {\displaystyle C\subseteq X} be convex.
Every subset A of the vector space is contained within a smallest convex set (called the convex hull of A), namely the intersection of all convex sets containing A. The convex-hull operator Conv() has the characteristic properties of a hull operator:
The convex-hull operation is needed for the set of convex sets to form a lattice, in which the "join" operation is the convex hull of the union of two convex sets
The intersection of any collection of convex sets is itself convex, so the convex subsets of a (real or complex) vector space form a complete lattice.
In a real vector-space, the Minkowski sum of two (non-empty) sets, S1 and S2, is defined to be the set S1 + S2 formed by the addition of vectors element-wise from the summand-sets
More generally, the Minkowski sum of a finite family of (non-empty) sets Sn is the set formed by element-wise addition of vectors
For Minkowski addition, the zero set {0} containing only the zero vector 0 has special importance: For every non-empty subset S of a vector space
in algebraic terminology, {0} is the identity element of Minkowski addition (on the collection of non-empty sets).
Minkowski addition behaves well with respect to the operation of taking convex hulls, as shown by the following proposition:
Let S1, S2 be subsets of a real vector-space, the convex hull of their Minkowski sum is the Minkowski sum of their convex hulls
This result holds more generally for each finite collection of non-empty sets:
In mathematical terminology, the operations of Minkowski summation and of forming convex hulls are commuting operations.
The Minkowski sum of two compact convex sets is compact. The sum of a compact convex set and a closed convex set is closed.
The following famous theorem, proved by Dieudonné in 1966, gives a sufficient condition for the difference of two closed convex subsets to be closed. It uses the concept of a recession cone of a non-empty convex subset S, defined as:
where this set is a convex cone containing 0 ∈ X {\displaystyle 0\in X} and satisfying S + rec S = S {\displaystyle S+\operatorname {rec} S=S} . Note that if S is closed and convex then rec S {\displaystyle \operatorname {rec} S} is closed and for all s 0 ∈ S {\displaystyle s_{0}\in S} ,
Theorem (Dieudonné). Let A and B be non-empty, closed, and convex subsets of a locally convex topological vector space such that rec A ∩ rec B {\displaystyle \operatorname {rec} A\cap \operatorname {rec} B} is a linear subspace. If A or B is locally compact then A − B is closed.
The notion of convexity in the Euclidean space may be generalized by modifying the definition in some or other aspects. The common name "generalized convexity" is used, because the resulting objects retain certain properties of convex sets.
Let C be a set in a real or complex vector space. C is star convex (star-shaped) if there exists an x0 in C such that the line segment from x0 to any point y in C is contained in C. Hence a non-empty convex set is always star-convex but a star-convex set is not always convex.
An example of generalized convexity is orthogonal convexity.
A set S in the Euclidean space is called orthogonally convex or ortho-convex, if any segment parallel to any of the coordinate axes connecting two points of S lies totally within S. It is easy to prove that an intersection of any collection of orthoconvex sets is orthoconvex. Some other properties of convex sets are valid as well.
The definition of a convex set and a convex hull extends naturally to geometries which are not Euclidean by defining a geodesically convex set to be one that contains the geodesics joining any two points in the set.
Convexity can be extended for a totally ordered set X endowed with the order topology.
Let Y ⊆ X. The subspace Y is a convex set if for each pair of points a, b in Y such that a ≤ b, the interval [a, b] = {x ∈ X | a ≤ x ≤ b} is contained in Y. That is, Y is convex if and only if for all a, b in Y, a ≤ b implies [a, b] ⊆ Y.
A convex set is not connected in general: a counter-example is given by the subspace {1,2,3} in Z, which is both convex and not connected.
The notion of convexity may be generalised to other objects, if certain properties of convexity are selected as axioms.
Given a set X, a convexity over X is a collection 𝒞 of subsets of X satisfying the following axioms:
The elements of 𝒞 are called convex sets and the pair (X, 𝒞) is called a convexity space. For the ordinary convexity, the first two axioms hold, and the third one is trivial.
For an alternative definition of abstract convexity, more suited to discrete geometry, see the convex geometries associated with antimatroids.
Convexity can be generalised as an abstract algebraic structure: a space is convex if it is possible to take convex combinations of points. | [
{
"paragraph_id": 0,
"text": "In geometry, a subset of a Euclidean space, or more generally an affine space over the reals, is convex if, given any two points in the subset, the subset contains the whole line segment that joins them. Equivalently, a convex set or a convex region is a subset that intersects every line into a single line segment (possibly empty). For example, a solid cube is a convex set, but anything that is hollow or has an indent, for example, a crescent shape, is not convex.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The boundary of a convex set is always a convex curve. The intersection of all the convex sets that contain a given subset A of Euclidean space is called the convex hull of A. It is the smallest convex set containing A.",
"title": ""
},
{
"paragraph_id": 2,
"text": "A convex function is a real-valued function defined on an interval with the property that its epigraph (the set of points on or above the graph of the function) is a convex set. Convex minimization is a subfield of optimization that studies the problem of minimizing convex functions over convex sets. The branch of mathematics devoted to the study of properties of convex sets and convex functions is called convex analysis.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The notion of a convex set can be generalized as described below.",
"title": ""
},
{
"paragraph_id": 4,
"text": "Let S be a vector space or an affine space over the real numbers, or, more generally, over some ordered field (this includes Euclidean spaces, which are affine spaces). A subset C of S is convex if, for all x and y in C, the line segment connecting x and y is included in C.",
"title": "Definitions"
},
{
"paragraph_id": 5,
"text": "This means that the affine combination (1 − t)x + ty belongs to C for all x,y in C and t in the interval [0, 1]. This implies that convexity is invariant under affine transformations. Further, it implies that a convex set in a real or complex topological vector space is path-connected (and therefore also connected).",
"title": "Definitions"
},
{
"paragraph_id": 6,
"text": "A set C is strictly convex if every point on the line segment connecting x and y other than the endpoints is inside the topological interior of C. A closed convex subset is strictly convex if and only if every one of its boundary points is an extreme point.",
"title": "Definitions"
},
{
"paragraph_id": 7,
"text": "A set C is absolutely convex if it is convex and balanced.",
"title": "Definitions"
},
{
"paragraph_id": 8,
"text": "The convex subsets of R (the set of real numbers) are the intervals and the points of R. Some examples of convex subsets of the Euclidean plane are solid regular polygons, solid triangles, and intersections of solid triangles. Some examples of convex subsets of a Euclidean 3-dimensional space are the Archimedean solids and the Platonic solids. The Kepler-Poinsot polyhedra are examples of non-convex sets.",
"title": "Definitions"
},
{
"paragraph_id": 9,
"text": "A set that is not convex is called a non-convex set. A polygon that is not a convex polygon is sometimes called a concave polygon, and some sources more generally use the term concave set to mean a non-convex set, but most authorities prohibit this usage.",
"title": "Definitions"
},
{
"paragraph_id": 10,
"text": "The complement of a convex set, such as the epigraph of a concave function, is sometimes called a reverse convex set, especially in the context of mathematical optimization.",
"title": "Definitions"
},
{
"paragraph_id": 11,
"text": "Given r points u1, ..., ur in a convex set S, and r nonnegative numbers λ1, ..., λr such that λ1 + ... + λr = 1, the affine combination",
"title": "Properties"
},
{
"paragraph_id": 12,
"text": "belongs to S. As the definition of a convex set is the case r = 2, this property characterizes convex sets.",
"title": "Properties"
},
{
"paragraph_id": 13,
"text": "Such an affine combination is called a convex combination of u1, ..., ur.",
"title": "Properties"
},
{
"paragraph_id": 14,
"text": "The collection of convex subsets of a vector space, an affine space, or a Euclidean space has the following properties:",
"title": "Properties"
},
{
"paragraph_id": 15,
"text": "Closed convex sets are convex sets that contain all their limit points. They can be characterised as the intersections of closed half-spaces (sets of point in space that lie on and to one side of a hyperplane).",
"title": "Properties"
},
{
"paragraph_id": 16,
"text": "From what has just been said, it is clear that such intersections are convex, and they will also be closed sets. To prove the converse, i.e., every closed convex set may be represented as such intersection, one needs the supporting hyperplane theorem in the form that for a given closed convex set C and point P outside it, there is a closed half-space H that contains C and not P. The supporting hyperplane theorem is a special case of the Hahn–Banach theorem of functional analysis.",
"title": "Properties"
},
{
"paragraph_id": 17,
"text": "Let C be a convex body in the plane (a convex set whose interior is non-empty). We can inscribe a rectangle r in C such that a homothetic copy R of r is circumscribed about C. The positive homothety ratio is at most 2 and:",
"title": "Properties"
},
{
"paragraph_id": 18,
"text": "",
"title": "Properties"
},
{
"paragraph_id": 19,
"text": "The set K 2 {\\displaystyle {\\mathcal {K}}^{2}} of all planar convex bodies can be parameterized in terms of the convex body diameter D, its inradius r (the biggest circle contained in the convex body) and its circumradius R (the smallest circle containing the convex body). In fact, this set can be described by the set of inequalities given by",
"title": "Properties"
},
{
"paragraph_id": 20,
"text": "and can be visualized as the image of the function g that maps a convex body to the R point given by (r/R, D/2R). The image of this function is known a (r, D, R) Blachke-Santaló diagram.",
"title": "Properties"
},
{
"paragraph_id": 21,
"text": "Alternatively, the set K 2 {\\displaystyle {\\mathcal {K}}^{2}} can also be parametrized by its width (the smallest distance between any two different parallel support hyperplanes), perimeter and area.",
"title": "Properties"
},
{
"paragraph_id": 22,
"text": "Let X be a topological vector space and C ⊆ X {\\displaystyle C\\subseteq X} be convex.",
"title": "Properties"
},
{
"paragraph_id": 23,
"text": "Every subset A of the vector space is contained within a smallest convex set (called the convex hull of A), namely the intersection of all convex sets containing A. The convex-hull operator Conv() has the characteristic properties of a hull operator:",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 24,
"text": "The convex-hull operation is needed for the set of convex sets to form a lattice, in which the \"join\" operation is the convex hull of the union of two convex sets",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 25,
"text": "The intersection of any collection of convex sets is itself convex, so the convex subsets of a (real or complex) vector space form a complete lattice.",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 26,
"text": "In a real vector-space, the Minkowski sum of two (non-empty) sets, S1 and S2, is defined to be the set S1 + S2 formed by the addition of vectors element-wise from the summand-sets",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 27,
"text": "More generally, the Minkowski sum of a finite family of (non-empty) sets Sn is the set formed by element-wise addition of vectors",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 28,
"text": "For Minkowski addition, the zero set {0} containing only the zero vector 0 has special importance: For every non-empty subset S of a vector space",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 29,
"text": "in algebraic terminology, {0} is the identity element of Minkowski addition (on the collection of non-empty sets).",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 30,
"text": "Minkowski addition behaves well with respect to the operation of taking convex hulls, as shown by the following proposition:",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 31,
"text": "Let S1, S2 be subsets of a real vector-space, the convex hull of their Minkowski sum is the Minkowski sum of their convex hulls",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 32,
"text": "This result holds more generally for each finite collection of non-empty sets:",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 33,
"text": "In mathematical terminology, the operations of Minkowski summation and of forming convex hulls are commuting operations.",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 34,
"text": "The Minkowski sum of two compact convex sets is compact. The sum of a compact convex set and a closed convex set is closed.",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 35,
"text": "The following famous theorem, proved by Dieudonné in 1966, gives a sufficient condition for the difference of two closed convex subsets to be closed. It uses the concept of a recession cone of a non-empty convex subset S, defined as:",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 36,
"text": "where this set is a convex cone containing 0 ∈ X {\\displaystyle 0\\in X} and satisfying S + rec S = S {\\displaystyle S+\\operatorname {rec} S=S} . Note that if S is closed and convex then rec S {\\displaystyle \\operatorname {rec} S} is closed and for all s 0 ∈ S {\\displaystyle s_{0}\\in S} ,",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 37,
"text": "Theorem (Dieudonné). Let A and B be non-empty, closed, and convex subsets of a locally convex topological vector space such that rec A ∩ rec B {\\displaystyle \\operatorname {rec} A\\cap \\operatorname {rec} B} is a linear subspace. If A or B is locally compact then A − B is closed.",
"title": "Convex hulls and Minkowski sums"
},
{
"paragraph_id": 38,
"text": "The notion of convexity in the Euclidean space may be generalized by modifying the definition in some or other aspects. The common name \"generalized convexity\" is used, because the resulting objects retain certain properties of convex sets.",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 39,
"text": "Let C be a set in a real or complex vector space. C is star convex (star-shaped) if there exists an x0 in C such that the line segment from x0 to any point y in C is contained in C. Hence a non-empty convex set is always star-convex but a star-convex set is not always convex.",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 40,
"text": "An example of generalized convexity is orthogonal convexity.",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 41,
"text": "A set S in the Euclidean space is called orthogonally convex or ortho-convex, if any segment parallel to any of the coordinate axes connecting two points of S lies totally within S. It is easy to prove that an intersection of any collection of orthoconvex sets is orthoconvex. Some other properties of convex sets are valid as well.",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 42,
"text": "The definition of a convex set and a convex hull extends naturally to geometries which are not Euclidean by defining a geodesically convex set to be one that contains the geodesics joining any two points in the set.",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 43,
"text": "Convexity can be extended for a totally ordered set X endowed with the order topology.",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 44,
"text": "Let Y ⊆ X. The subspace Y is a convex set if for each pair of points a, b in Y such that a ≤ b, the interval [a, b] = {x ∈ X | a ≤ x ≤ b} is contained in Y. That is, Y is convex if and only if for all a, b in Y, a ≤ b implies [a, b] ⊆ Y.",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 45,
"text": "A convex set is not connected in general: a counter-example is given by the subspace {1,2,3} in Z, which is both convex and not connected.",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 46,
"text": "The notion of convexity may be generalised to other objects, if certain properties of convexity are selected as axioms.",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 47,
"text": "Given a set X, a convexity over X is a collection 𝒞 of subsets of X satisfying the following axioms:",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 48,
"text": "The elements of 𝒞 are called convex sets and the pair (X, 𝒞) is called a convexity space. For the ordinary convexity, the first two axioms hold, and the third one is trivial.",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 49,
"text": "For an alternative definition of abstract convexity, more suited to discrete geometry, see the convex geometries associated with antimatroids.",
"title": "Generalizations and extensions for convexity"
},
{
"paragraph_id": 50,
"text": "Convexity can be generalised as an abstract algebraic structure: a space is convex if it is possible to take convex combinations of points.",
"title": "Generalizations and extensions for convexity"
}
] | In geometry, a subset of a Euclidean space, or more generally an affine space over the reals, is convex if, given any two points in the subset, the subset contains the whole line segment that joins them. Equivalently, a convex set or a convex region is a subset that intersects every line into a single line segment.
For example, a solid cube is a convex set, but anything that is hollow or has an indent, for example, a crescent shape, is not convex. The boundary of a convex set is always a convex curve. The intersection of all the convex sets that contain a given subset A of Euclidean space is called the convex hull of A. It is the smallest convex set containing A. A convex function is a real-valued function defined on an interval with the property that its epigraph is a convex set. Convex minimization is a subfield of optimization that studies the problem of minimizing convex functions over convex sets. The branch of mathematics devoted to the study of properties of convex sets and convex functions is called convex analysis. The notion of a convex set can be generalized as described below. | 2001-09-21T19:58:47Z | 2023-08-09T23:52:13Z | [
"Template:Mvar",
"Template:Cite journal",
"Template:Short description",
"Template:Visible anchor",
"Template:Halmos A Hilbert Space Problem Book 1982",
"Template:ISBN",
"Template:Authority control",
"Template:Em",
"Template:Div col end",
"Template:Reflist",
"Template:Functional analysis",
"Template:Wiktionary",
"Template:Springer",
"Template:Convex analysis and variational analysis",
"Template:Math",
"Template:Main",
"Template:Div col",
"Template:Cite book",
"Template:MathWorld"
] | https://en.wikipedia.org/wiki/Convex_set |
6,293 | Cairo | Cairo (/ˈkaɪroʊ/ KY-roh; Arabic: القاهرة, romanized: al-Qāhirah, pronounced [ælqɑ(ː)ˈheɾɑ] ) is the capital of Egypt and the city-state Cairo Governorate, and is the country's largest city, home to 10 million people. It is also part of the largest urban agglomeration in Africa, the Arab world and the Middle East: The Greater Cairo metropolitan area is the 12th-largest in the world by population with a population of over 22.1 million.
Cairo is associated with ancient Egypt, as the Giza pyramid complex and the ancient cities of Memphis and Heliopolis are located in its geographical area. Located near the Nile Delta, the city first developed as Fustat following the Muslim conquest of Egypt in 641 next to an existing ancient Roman fortress, Babylon. Cairo was founded by the Fatimid dynasty in 969. It later superseded Fustat as the main urban centre during the Ayyubid and Mamluk periods (12th–16th centuries). Cairo has long been a centre of the region's political and cultural life, and is titled "the city of a thousand minarets" for its preponderance of Islamic architecture. Cairo's historic center was awarded World Heritage Site status in 1979. Cairo is considered a World City with a "Beta +" classification according to GaWC.
Cairo has the oldest and largest film and music industry in the Arab world, as well as Egypt's oldest institution of higher learning, Al-Azhar University. Many international media, businesses, and organizations have regional headquarters in the city; the Arab League has had its headquarters in Cairo for most of its existence.
With a population of over 10 million spread over 453 km (175 sq mi), Cairo is by far the largest city in Egypt. An additional 9.5 million inhabitants live close to the city. Cairo, like many other megacities, suffers from high levels of pollution and traffic. The Cairo Metro, opened in 1987, is the oldest metro system in Africa, and ranks amongst the fifteen busiest in the world, with over 1 billion annual passenger rides. The economy of Cairo was ranked first in the Middle East in 2005, and 43rd globally on Foreign Policy's 2010 Global Cities Index.
The name Cairo is derived from the Arabic al-Qāhirah (القاهرة), meaning 'the Vanquisher' or 'the Conqueror', given by the Fatimid Caliph al-Mu'izz following the establishment of the city as the capital of the Fatimid dynasty. Initially, its full name was Qāhirat al-Mu'izz, meaning 'the Vanquisher of al-Mu'izz'. It is also supposedly due to the fact that the planet Mars, known in Arabic by names such as an-Najm al-Qāhir (النجم القاهر, 'the Conquering Star'), was rising at the time of the city's founding.
Egyptians often refer to Cairo as Maṣr (IPA: [mɑsˤɾ]; مَصر), the Egyptian Arabic name for Egypt itself, emphasizing the city's importance for the country.
There are a number of Coptic names for the city. Tikešrōmi (Coptic: Ϯⲕⲉϣⲣⲱⲙⲓ Late Coptic: [di.kɑʃˈɾoːmi]) is attested in the 1211 text The Martyrdom of John of Phanijoit and is either a calque meaning 'man breaker' (Ϯ-, 'the', ⲕⲁϣ-, 'to break', and ⲣⲱⲙⲓ, 'man'), akin to Arabic al-Qāhirah, or a derivation from Arabic قَصْر الرُوم (qaṣr ar-rūm, "the Roman castle"), another name of Babylon Fortress in Old Cairo. The Arabic name is also calqued as ⲧⲡⲟⲗⲓⲥ ϯⲣⲉϥϭⲣⲟ, "the victor city" in the Coptic antiphonary.
The form Khairon (Coptic: ⲭⲁⲓⲣⲟⲛ) is attested in the modern Coptic text Ⲡⲓⲫⲓⲣⲓ ⲛ̀ⲧⲉ ϯⲁⲅⲓⲁ ⲙ̀ⲙⲏⲓ Ⲃⲉⲣⲏⲛⲁ (The Tale of Saint Verina). Lioui (Ⲗⲓⲟⲩⲓ Late Coptic: [lɪˈjuːj]) or Elioui (Ⲉⲗⲓⲟⲩⲓ Late Coptic: [ælˈjuːj]) is another name which is descended from the Greek name of Heliopolis (Ήλιούπολις). Some argue that Mistram (Ⲙⲓⲥⲧⲣⲁⲙ Late Coptic: [ˈmɪs.təɾɑm]) or Nistram (Ⲛⲓⲥⲧⲣⲁⲙ Late Coptic: [ˈnɪs.təɾɑm]) is another Coptic name for Cairo, although others think that it is rather a name for the Abbasid province capital al-Askar. Ⲕⲁϩⲓⲣⲏ (Kahi•ree) is a popular modern rendering of an Arabic name (others being Ⲕⲁⲓⲣⲟⲛ [Kairon] and Ⲕⲁϩⲓⲣⲁ [Kahira]) which is modern folk etymology meaning 'land of sun'. Some argue that it was a name of an Egyptian settlement upon which Cairo was built, but it is rather doubtful as this name is not attested in any Hieroglyphic or Demotic source, although some researchers, like Paul Casanova, view it as a legitimate theory. Cairo is also referred to as Ⲭⲏⲙⲓ (Late Coptic: [ˈkɪ.mi]) or Ⲅⲩⲡⲧⲟⲥ (Late Coptic: [ˈɡɪp.dos]), which means Egypt in Coptic, the same way it is referred to in Egyptian Arabic.
Sometimes the city is informally referred to as Cairo by people from Alexandria (IPA: [ˈkæjɾo]; Egyptian Arabic: كايرو).
The area around present-day Cairo had long been a focal point of Ancient Egypt due to its strategic location at the junction of the Nile Valley and the Nile Delta regions (roughly Upper Egypt and Lower Egypt), which also placed it at the crossing of major routes between North Africa and the Levant. Memphis, the capital of Egypt during the Old Kingdom and a major city up until the Ptolemaic period, was located a short distance south west of present-day Cairo. Heliopolis, another important city and major religious center, was located in what are now the modern districts of Matariya and Ain Shams in northeastern Cairo. It was largely destroyed by the Persian invasions in 525 BC and 343 BC and partly abandoned by the late first century BC.
However, the origins of modern Cairo are generally traced back to a series of settlements in the first millennium AD. Around the turn of the fourth century, as Memphis was continuing to decline in importance, the Romans established a large fortress along the east bank of the Nile. The fortress, called Babylon, was built by the Roman emperor Diocletian (r. 285–305) at the entrance of a canal connecting the Nile to the Red Sea that was created earlier by emperor Trajan (r. 98–115). Further north of the fortress, near the present-day district of al-Azbakiya, was a port and fortified outpost known as Tendunyas (Coptic: ϯⲁⲛⲧⲱⲛⲓⲁⲥ) or Umm Dunayn. While no structures older than the 7th century have been preserved in the area aside from the Roman fortifications, historical evidence suggests that a sizeable city existed. The city was important enough that its bishop, Cyrus, participated in the Second Council of Ephesus in 449.
The Byzantine-Sassanian War between 602 and 628 caused great hardship and likely caused much of the urban population to leave for the countryside, leaving the settlement partly deserted. The site today remains at the nucleus of the Coptic Orthodox community, which separated from the Roman and Byzantine churches in the late 4th century. Cairo's oldest extant churches, such as the Church of Saint Barbara and the Church of Saints Sergius and Bacchus (from the late 7th or early 8th century), are located inside the fortress walls in what is now known as Old Cairo or Coptic Cairo.
The Muslim conquest of Byzantine Egypt was led by Amr ibn al-As from 639 to 642. Babylon Fortress was besieged in September 640 and fell in April 641. In 641 or early 642, after the surrender of Alexandria (the Egyptian capital at the time), he founded a new settlement next to Babylon Fortress. The city, known as Fustat (Arabic: الفسطاط, romanized: al-Fusṭāṭ, lit. 'the tent'), served as a garrison town and as the new administrative capital of Egypt. Historians such as Janet Abu-Lughod and André Raymond trace the genesis of present-day Cairo to the foundation of Fustat. The choice of founding a new settlement at this inland location, instead of using the existing capital of Alexandria on the Mediterranean coast, may have been due to the new conquerors' strategic priorities. One of the first projects of the new Muslim administration was to clear and re-open Trajan's ancient canal in order to ship grain more directly from Egypt to Medina, the capital of the caliphate in Arabia. Ibn al-As also founded a mosque for the city at the same time, now known as the Mosque of Amr Ibn al-As, the oldest mosque in Egypt and Africa (although the current structure dates from later expansions).
In 750, following the overthrow of the Umayyad caliphate by the Abbasids, the new rulers created their own settlement to the northeast of Fustat which became the new provincial capital. This was known as al-Askar (Arabic: العسكر, lit. 'the camp') as it was laid out like a military camp. A governor's residence and a new mosque were also added, with the latter completed in 786. In 861, on the orders of the Abbasid caliph al-Mutawakkil, a Nilometer was built on Roda Island near Fustat. Although it was repaired and given a new roof in later centuries, its basic structure is still preserved today, making it the oldest preserved Islamic-era structure in Cairo today.
In 868 a commander of Turkic origin named Bakbak was sent to Egypt by the Abbasid caliph al-Mu'taz to restore order after a rebellion in the country. He was accompanied by his stepson, Ahmad ibn Tulun, who became effective governor of Egypt. Over time, Ibn Tulun gained an army and accumulated influence and wealth, allowing him to become the de facto independent ruler of both Egypt and Syria by 878. In 870, he used his growing wealth to found a new administrative capital, al-Qata'i (Arabic: القطائـع, lit. 'the allotments'), to the northeast of Fustat and of al-Askar. The new city included a palace known as the Dar al-Imara, a parade ground known as al-Maydan, a bimaristan (hospital), and an aqueduct to supply water. Between 876 and 879 Ibn Tulun built a great mosque, now known as the Mosque of Ibn Tulun, at the center of the city, next to the palace. After his death in 884, Ibn Tulun was succeeded by his son and his descendants who continued a short-lived dynasty, the Tulunids. In 905, the Abbasids sent general Muhammad Sulayman al-Katib to re-assert direct control over the country. Tulunid rule was ended and al-Qatta'i was razed to the ground, except for the mosque which remains standing today.
In 969, the Shi'a Isma'ili Fatimid empire conquered Egypt after ruling from Ifriqiya. The Fatimid general Jawhar Al Saqili founded a new fortified city northeast of Fustat and of former al-Qata'i. It took four years to build the city, initially known as al-Manṣūriyyah, which was to serve as the new capital of the caliphate. During that time, the construction of the al-Azhar Mosque was commissioned by order of the caliph, which developed into the third-oldest university in the world. Cairo would eventually become a centre of learning, with the library of Cairo containing hundreds of thousands of books. When Caliph al-Mu'izz li Din Allah arrived from the old Fatimid capital of Mahdia in Tunisia in 973, he gave the city its present name, Qāhirat al-Mu'izz ("The Vanquisher of al-Mu'izz"), from which the name "Cairo" (al-Qāhira) originates. The caliphs lived in a vast and lavish palace complex that occupied the heart of the city. Cairo remained a relatively exclusive royal city for most of this era, but during the tenure of Badr al-Gamali as vizier (1073–1094) the restrictions were loosened for the first time and richer families from Fustat were allowed to move into the city. Between 1087 and 1092 Badr al-Gamali also rebuilt the city walls in stone and constructed the city gates of Bab al-Futuh, Bab al-Nasr, and Bab Zuweila that still stand today.
During the Fatimid period Fustat reached its apogee in size and prosperity, acting as a center of craftsmanship and international trade and as the area's main port on the Nile. Historical sources report that multi-story communal residences existed in the city, particularly in its center, which were typically inhabited by middle and lower-class residents. Some of these were as high as seven stories and could house some 200 to 350 people. They may have been similar to Roman insulae and may have been the prototypes for the rental apartment complexes which became common in the later Mamluk and Ottoman periods.
However, in 1168 the Fatimid vizier Shawar set fire to unfortified Fustat to prevent its potential capture by Amalric, the Crusader king of Jerusalem. While the fire did not destroy the city and it continued to exist afterward, it did mark the beginning of its decline. Over the following centuries it was Cairo, the former palace-city, that became the new economic center and attracted migration from Fustat.
While the Crusaders did not capture the city in 1168, a continuing power struggle between Shawar, King Amalric, and the Zengid general Shirkuh led to the downfall of the Fatimid establishment. In 1169, Shirkuh's nephew Saladin was appointed as the new vizier of Egypt by the Fatimids and two years later he seized power from the family of the last Fatimid caliph, al-'Āḍid. As the first Sultan of Egypt, Saladin established the Ayyubid dynasty, based in Cairo, and aligned Egypt with the Sunni Abbasids, who were based in Baghdad. In 1176, Saladin began construction on the Cairo Citadel, which was to serve as the seat of the Egyptian government until the mid-19th century. The construction of the Citadel definitively ended Fatimid-built Cairo's status as an exclusive palace-city and opened it up to common Egyptians and to foreign merchants, spurring its commercial development. Along with the Citadel, Saladin also began the construction of a new 20-kilometre-long wall that would protect both Cairo and Fustat on their eastern side and connect them with the new Citadel. These construction projects continued beyond Saladin's lifetime and were completed under his Ayyubid successors.
In 1250, during the Seventh Crusade, the Ayyubid dynasty had a crisis with the death of al-Salih and power transitioned instead to the Mamluks, partly with the help of al-Salih's wife, Shajar ad-Durr, who ruled for a brief period around this time. Mamluks were soldiers who were purchased as young slaves and raised to serve in the sultan's army. Between 1250 and 1517 the throne of the Mamluk Sultanate passed from one mamluk to another in a system of succession that was generally non-hereditary, but also frequently violent and chaotic. The Mamluk Empire nonetheless became a major power in the region and was responsible for repelling the advance of the Mongols (most famously at the Battle of Ain Jalut in 1260) and for eliminating the last Crusader states in the Levant.
Despite their military character, the Mamluks were also prolific builders and left a rich architectural legacy throughout Cairo. Continuing a practice started by the Ayyubids, much of the land occupied by former Fatimid palaces was sold and replaced by newer buildings, becoming a prestigious site for the construction of Mamluk religious and funerary complexes. Construction projects initiated by the Mamluks pushed the city outward while also bringing new infrastructure to the centre of the city. Meanwhile, Cairo flourished as a centre of Islamic scholarship and a crossroads on the spice trade route among the civilisations in Afro-Eurasia. Under the reign of the Mamluk sultan al-Nasir Muhammad (1293–1341, with interregnums), Cairo reached its apogee in terms of population and wealth. By 1340, Cairo had a population of close to half a million, making it the largest city west of China.
Multi-story buildings occupied by rental apartments, known as a rab' (plural ribā' or urbu), became common in the Mamluk period and continued to be a feature of the city's housing during the later Ottoman period. These apartments were often laid out as multi-story duplexes or triplexes. They were sometimes attached to caravanserais, where the two lower floors were for commercial and storage purposes and the multiple stories above them were rented out to tenants. The oldest partially-preserved example of this type of structure is the Wikala of Amir Qawsun, built before 1341. Residential buildings were in turn organized into close-knit neighbourhoods called a harat, which in many cases had gates that could be closed off at night or during disturbances.
When the traveller Ibn Battuta first came to Cairo in 1326, he described it as the principal district of Egypt. When he passed through the area again on his return journey in 1348 the Black Death was ravaging most major cities. He cited reports of thousands of deaths per day in Cairo. Although Cairo avoided Europe's stagnation during the Late Middle Ages, it could not escape the Black Death, which struck the city more than fifty times between 1348 and 1517. During its initial, and most deadly waves, approximately 200,000 people were killed by the plague, and, by the 15th century, Cairo's population had been reduced to between 150,000 and 300,000. The population decline was accompanied by a period of political instability between 1348 and 1412. It was nonetheless in this period that the largest Mamluk-era religious monument, the Madrasa-Mosque of Sultan Hasan, was built. In the late 14th century the Burji Mamluks replaced the Bahri Mamluks as rulers of the Mamluk state, but the Mamluk system continued to decline.
Though the plagues returned frequently throughout the 15th century, Cairo remained a major metropolis and its population recovered in part through rural migration. More conscious efforts were conducted by rulers and city officials to redress the city's infrastructure and cleanliness. Its economy and politics also became more deeply connected with the wider Mediterranean. Some Mamluk sultans in this period, such as Barbsay (r. 1422–1438) and Qaytbay (r. 1468–1496), had relatively long and successful reigns. After al-Nasir Muhammad, Qaytbay was one of the most prolific patrons of art and architecture of the Mamluk era. He built or restored numerous monuments in Cairo, in addition to commissioning projects beyond Egypt. The crisis of Mamluk power and of Cairo's economic role deepened after Qaytbay. The city's status was diminished after Vasco da Gama discovered a sea route around the Cape of Good Hope between 1497 and 1499, thereby allowing spice traders to avoid Cairo.
Cairo's political influence diminished significantly after the Ottomans defeated Sultan al-Ghuri in the Battle of Marj Dabiq in 1516 and conquered Egypt in 1517. Ruling from Constantinople, Sultan Selim I relegated Egypt to a province, with Cairo as its capital. For this reason, the history of Cairo during Ottoman times is often described as inconsequential, especially in comparison to other time periods.
During the 16th and 17th centuries, Cairo still remained an important economic and cultural centre. Although no longer on the spice route, the city facilitated the transportation of Yemeni coffee and Indian textiles, primarily to Anatolia, North Africa, and the Balkans. Cairene merchants were instrumental in bringing goods to the barren Hejaz, especially during the annual hajj to Mecca. It was during this same period that al-Azhar University reached the predominance among Islamic schools that it continues to hold today; pilgrims on their way to hajj often attested to the superiority of the institution, which had become associated with Egypt's body of Islamic scholars. The first printing press of the Middle East, printing in Hebrew, was established in Cairo c. 1557 by a scion of the Soncino family of printers, Italian Jews of Ashkenazi origin who operated a press in Constantinople. The existence of the press is known solely from two fragments discovered in the Cairo Geniza.
Under the Ottomans, Cairo expanded south and west from its nucleus around the Citadel. The city was the second-largest in the empire, behind Constantinople, and, although migration was not the primary source of Cairo's growth, twenty percent of its population at the end of the 18th century consisted of religious minorities and foreigners from around the Mediterranean. Still, when Napoleon arrived in Cairo in 1798, the city's population was less than 300,000, forty percent lower than it was at the height of Mamluk—and Cairene—influence in the mid-14th century.
The French occupation was short-lived as British and Ottoman forces, including a sizeable Albanian contingent, recaptured the country in 1801. Cairo itself was besieged by a British and Ottoman force culminating with the French surrender on 22 June 1801. The British vacated Egypt two years later, leaving the Ottomans, the Albanians, and the long-weakened Mamluks jostling for control of the country. Continued civil war allowed an Albanian named Muhammad Ali Pasha to ascend to the role of commander and eventually, with the approval of the religious establishment, viceroy of Egypt in 1805.
Until his death in 1848, Muhammad Ali Pasha instituted a number of social and economic reforms that earned him the title of founder of modern Egypt. However, while Muhammad Ali initiated the construction of public buildings in the city, those reforms had minimal effect on Cairo's landscape. Bigger changes came to Cairo under Isma'il Pasha (r. 1863–1879), who continued the modernisation processes started by his grandfather. Drawing inspiration from Paris, Isma'il envisioned a city of maidans and wide avenues; due to financial constraints, only some of them, in the area now composing Downtown Cairo, came to fruition. Isma'il also sought to modernize the city, which was merging with neighbouring settlements, by establishing a public works ministry, bringing gas and lighting to the city, and opening a theatre and opera house.
The immense debt resulting from Isma'il's projects provided a pretext for increasing European control, which culminated with the British invasion in 1882. The city's economic centre quickly moved west toward the Nile, away from the historic Islamic Cairo section and toward the contemporary, European-style areas built by Isma'il. Europeans accounted for five percent of Cairo's population at the end of the 19th century, by which point they held most top governmental positions.
In 1906 the Heliopolis Oasis Company headed by the Belgian industrialist Édouard Empain and his Egyptian counterpart Boghos Nubar, built a suburb called Heliopolis (city of the sun in Greek) ten kilometers from the center of Cairo. In 1905–1907 the northern part of the Gezira island was developed by the Baehler Company into Zamalek, which would later become Cairo's upscale "chic" neighbourhood. In 1906 construction began on Garden City, a neighbourhood of urban villas with gardens and curved streets.
The British occupation was intended to be temporary, but it lasted well into the 20th century. Nationalists staged large-scale demonstrations in Cairo in 1919, five years after Egypt had been declared a British protectorate. Nevertheless, this led to Egypt's independence in 1922.
The King Fuad I Edition of the Qur'an was first published on 10 July 1924 in Cairo under the patronage of King Fuad. The goal of the government of the newly formed Kingdom of Egypt was not to delegitimize the other variant Quranic texts ("qira'at"), but to eliminate errors found in Qur'anic texts used in state schools. A committee of teachers chose to preserve a single one of the canonical qira'at "readings", namely that of the "Ḥafṣ" version, an 8th-century Kufic recitation. This edition has become the standard for modern printings of the Quran for much of the Islamic world. The publication has been called a "terrific success", and the edition has been described as one "now widely seen as the official text of the Qur'an", so popular among both Sunni and Shi'a that the common belief among less well-informed Muslims is "that the Qur'an has a single, unambiguous reading". Minor amendments were made later in 1924 and in 1936 - the "Faruq edition" in honour of then ruler, King Faruq.
British troops remained in the country until 1956. During this time, urban Cairo, spurred by new bridges and transport links, continued to expand to include the upscale neighbourhoods of Garden City, Zamalek, and Heliopolis. Between 1882 and 1937, the population of Cairo more than tripled—from 347,000 to 1.3 million—and its area increased from 10 to 163 km (4 to 63 sq mi).
The city was devastated during the 1952 riots known as the Cairo Fire or Black Saturday, which saw the destruction of nearly 700 shops, movie theatres, casinos and hotels in downtown Cairo. The British departed Cairo following the Egyptian Revolution of 1952, but the city's rapid growth showed no signs of abating. Seeking to accommodate the increasing population, President Gamal Abdel Nasser redeveloped Tahrir Square and the Nile Corniche, and improved the city's network of bridges and highways. Meanwhile, additional controls of the Nile fostered development within Gezira Island and along the city's waterfront. The metropolis began to encroach on the fertile Nile Delta, prompting the government to build desert satellite towns and devise incentives for city-dwellers to move to them.
In the second half of the 20th century Cairo continue to grow enormously in both population and area. Between 1947 and 2006 the population of Greater Cairo went from 2,986,280 to 16,292,269. The population explosion also drove the rise of "informal" housing ('ashwa'iyyat), meaning housing that was built without any official planning or control. The exact form of this type of housing varies considerably but usually has a much higher population density than formal housing. By 2009, over 63% of the population of Greater Cairo lived in informal neighbourhoods, even though these occupied only 17% of the total area of Greater Cairo. According to economist David Sims, informal housing has the benefits of providing affordable accommodation and vibrant communities to huge numbers of Cairo's working classes, but it also suffers from government neglect, a relative lack of services, and overcrowding.
The "formal" city was also expanded. The most notable example was the creation of Madinat Nasr, a huge government-sponsored expansion of the city to the east which officially began in 1959 but was primarily developed in the mid-1970s. Starting in 1977 the Egyptian government established the New Urban Communities Authority to initiate and direct the development of new planned cities on the outskirts of Cairo, generally established on desert land. These new satellite cities were intended to provide housing, investment, and employment opportunities for the region's growing population as well as to pre-empt the further growth of informal neighbourhoods. As of 2014, about 10% of the population of Greater Cairo lived in the new cities.
Concurrently, Cairo established itself as a political and economic hub for North Africa and the Arab world, with many multinational businesses and organisations, including the Arab League, operating out of the city. In 1979 the historic districts of Cairo were listed as a UNESCO World Heritage Site.
In 1992, Cairo was hit by an earthquake causing 545 deaths, injuring 6,512 and leaving around 50,000 people homeless.
Cairo's Tahrir Square was the focal point of the 2011 Egyptian Revolution against former president Hosni Mubarak. Over 2 million protesters were at Cairo's Tahrir square. More than 50,000 protesters first occupied the square on 25 January, during which the area's wireless services were reported to be impaired. In the following days Tahrir Square continued to be the primary destination for protests in Cairo as it took place following a popular uprising that began on Tuesday, 25 January 2011 and continued until June 2013. The uprising was mainly a campaign of non-violent civil resistance, which featured a series of demonstrations, marches, acts of civil disobedience, and labour strikes. Millions of protesters from a variety of socio-economic and religious backgrounds demanded the overthrow of the regime of Egyptian President Hosni Mubarak. Despite being predominantly peaceful in nature, the revolution was not without violent clashes between security forces and protesters, with at least 846 people killed and 6,000 injured. The uprising took place in Cairo, Alexandria, and in other cities in Egypt, following the Tunisian revolution that resulted in the overthrow of the long-time Tunisian president Zine El Abidine Ben Ali. On 11 February, following weeks of determined popular protest and pressure, Hosni Mubarak resigned from office.
Under the rule of President el-Sisi, in March 2015 plans were announced for another yet-unnamed planned city to be built further east of the existing satellite city of New Cairo, intended to serve as the new capital of Egypt.
Cairo is located in northern Egypt, known as Lower Egypt, 165 km (100 mi) south of the Mediterranean Sea and 120 km (75 mi) west of the Gulf of Suez and Suez Canal. The city lies along the Nile River, immediately south of the point where the river leaves its desert-bound valley and branches into the low-lying Nile Delta region. Although the Cairo metropolis extends away from the Nile in all directions, the city of Cairo resides only on the east bank of the river and two islands within it on a total area of 453 km (175 sq mi). Geologically, Cairo lies on alluvium and sand dunes which date from the quaternary period.
Until the mid-19th century, when the river was tamed by dams, levees, and other controls, the Nile in the vicinity of Cairo was highly susceptible to changes in course and surface level. Over the years, the Nile gradually shifted westward, providing the site between the eastern edge of the river and the Mokattam highlands on which the city now stands. The land on which Cairo was established in 969 (present-day Islamic Cairo) was located underwater just over three hundred years earlier, when Fustat was first built.
Low periods of the Nile during the 11th century continued to add to the landscape of Cairo; a new island, known as Geziret al-Fil, first appeared in 1174, but eventually became connected to the mainland. Today, the site of Geziret al-Fil is occupied by the Shubra district. The low periods created another island at the turn of the 14th century that now composes Zamalek and Gezira. Land reclamation efforts by the Mamluks and Ottomans further contributed to expansion on the east bank of the river.
Because of the Nile's movement, the newer parts of the city—Garden City, Downtown Cairo, and Zamalek—are located closest to the riverbank. The areas, which are home to most of Cairo's embassies, are surrounded on the north, east, and south by the older parts of the city. Old Cairo, located south of the centre, holds the remnants of Fustat and the heart of Egypt's Coptic Christian community, Coptic Cairo. The Boulaq district, which lies in the northern part of the city, was born out of a major 16th-century port and is now a major industrial centre. The Citadel is located east of the city centre around Islamic Cairo, which dates back to the Fatimid era and the foundation of Cairo. While western Cairo is dominated by wide boulevards, open spaces, and modern architecture of European influence, the eastern half, having grown haphazardly over the centuries, is dominated by small lanes, crowded tenements, and Islamic architecture.
Northern and extreme eastern parts of Cairo, which include satellite towns, are among the most recent additions to the city, as they developed in the late-20th and early-21st centuries to accommodate the city's rapid growth. The western bank of the Nile is commonly included within the urban area of Cairo, but it composes the city of Giza and the Giza Governorate. Giza city has also undergone significant expansion over recent years, and today has a population of 2.7 million. The Cairo Governorate was just north of the Helwan Governorate from 2008 when some Cairo's southern districts, including Maadi and New Cairo, were split off and annexed into the new governorate, to 2011 when the Helwan Governorate was reincorporated into the Cairo Governorate.
According to the World Health Organization, the level of air pollution in Cairo is nearly 12 times higher than the recommended safety level.
In Cairo, and along the Nile River Valley, the climate is a hot desert climate (BWh according to the Köppen climate classification system). Wind storms can be frequent, bringing Saharan dust into the city, from March to May and the air often becomes uncomfortably dry. High temperatures in winter range from 14 to 22 °C (57 to 72 °F), while night-time lows drop to below 11 °C (52 °F), often to 5 °C (41 °F). In summer, the highs rarely surpass 40 °C (104 °F), and lows drop to about 20 °C (68 °F). Rainfall is sparse and only happens in the colder months, but sudden showers can cause severe flooding. The summer months have high humidity due to its coastal location. Snowfall is extremely rare; a small amount of graupel, widely believed to be snow, fell on Cairo's easternmost suburbs on 13 December 2013, the first time Cairo's area received this kind of precipitation in many decades. Dew points in the hottest months range from 13.9 °C (57 °F) in June to 18.3 °C (65 °F) in August.
The city of Cairo forms part of Greater Cairo, the largest metropolitan area in Africa. While it has no administrative body, the Ministry of Planning considers it as an economic region consisting of Cairo Governorate, Giza Governorate, and Qalyubia Governorate. As a contiguous metropolitan area, various studies have considered Greater Cairo be composed of the administrative cities that are Cairo, Giza and Shubra al-Kheima, in addition to the satellite cities/new towns surrounding them.
Cairo is a city-state where the governor is also the head of the city. Cairo City itself differs from other Egyptian cities in that it has an extra administrative division between the city and district levels, and that is areas, which are headed by deputy governors. Cairo consists of 4 areas (manatiq, singl. mantiqa) divided into 38 districts (ahya', singl. hayy) and 46 qisms (police wards, 1-2 per district):
The Northern Area is divided into 8 Districts:
The Eastern Area divided into 9 Districts and three new cities:
The Western Area divided into 9 Districts:
The Southern Area divided into 12 Districts:
Since 1977 a number of new towns have been planned and built by the New Urban Communities Authority (NUCA) in the Eastern Desert around Cairo, ostensibly to accommodate additional population growth and development of the city and stem the development of self-built informal areas, especially over agricultural land. As of 2022 four new towns have been built and have residential populations: 15th of May City, Badr City, Shorouk City, and New Cairo. In addition, two more are under construction: the New Administrative Capital. And Capital Gardens, where land was allocated in 2021, and which will house most of the civil servants employed in the new capital.
In March 2015, plans were announced for a new city to be built east of Cairo, in an undeveloped area of the Cairo Governorate, which would serve as the New Administrative Capital of Egypt.
According to the 2017 census, Cairo had a population of 9,539,673 people, distributed across 46 qisms (police wards):
The majority of Egypt and Cairo's population is Sunni Muslim. A significant Christian minority exists, among whom Coptic Orthodox are the majority. Precise numbers for each religious community in Egypt are not available and estimates vary. Other churches that have, or had, a presence in modern Cairo include the Catholic Church (including Armenian Catholic, Coptic Catholic, Chaldean Catholic, Syrian Catholic, and Maronite), the Greek Orthodox Church, the Evangelical Church of Egypt (Synod of the Nile), and some Protestant churches. Until the 20th century, Cairo had a sizeable Jewish community, but as of 2022 only 3 Jews were reported to be living in the city. A total of 12 synagogues in Cairo still exist.
Cairo's economy has traditionally been based on governmental institutions and services, with the modern productive sector expanding in the 20th century to include developments in textiles and food processing – specifically the production of sugar cane. As of 2005, Egypt has the largest non-oil based GDP in the Arab world.
Cairo accounts for 11% of Egypt's population and 22% of its economy (PPP). The majority of the nation's commerce is generated there, or passes through the city. The great majority of publishing houses and media outlets and nearly all film studios are there, as are half of the nation's hospital beds and universities. This has fuelled rapid construction in the city, with one building in five being less than 15 years old.
This growth until recently surged well ahead of city services. Homes, roads, electricity, telephone and sewer services were all in short supply. Analysts trying to grasp the magnitude of the change coined terms like "hyper-urbanization".
Cairo, as well as neighbouring Giza, has been established as Egypt's main centre for medical treatment, and despite some exceptions, has the most advanced level of medical care in the country. Cairo's hospitals include the JCI-accredited As-Salaam International Hospital—Corniche El Nile, Maadi (Egypt's largest private hospital with 350 beds), Ain Shams University Hospital, Dar Al Fouad, Nile Badrawi Hospital, 57357 Hospital, as well as Qasr El Eyni Hospital.
Greater Cairo has long been the hub of education and educational services for Egypt and the region.
Today, Greater Cairo is the centre for many government offices governing the Egyptian educational system, has the largest number of educational schools, and higher education institutes among other cities and governorates of Egypt.
Some of the International Schools found in Cairo:
Universities in Greater Cairo:
Cairo has an extensive road network, rail system, subway system and maritime services. Road transport is facilitated by personal vehicles, taxi cabs, privately owned public buses and microbuses. Cairo International Airport is the country's largest airport and one of the busiest airports in Africa.
Cairo, specifically Ramses Station, is the centre of almost the entire Egyptian transportation network.
The Cairo Transportation Authority (CTA) manages Cairo's public transit. The subway system, the Cairo Metro, is a fast and efficient way of getting around Cairo. The metro network covers Helwan and other suburbs. It can get very crowded during rush hour. Two train cars (the fourth and fifth ones) are reserved for women only, although women may ride in any car they want.
Trams in Greater Cairo and Cairo trolleybus were used as modes of transportation, but were closed in the 1970s everywhere except Heliopolis and Helwan. These were shut down in 2014, after the Egyptian Revolution.
In 2017, plans to construct two monorail systems were announced, one linking 6th of October to suburban Giza, a distance of 35 km (22 mi), and the other linking Nasr City to New Cairo, a distance of 52 km (32 mi).
An extensive road network connects Cairo with other Egyptian cities and villages. There is a new Ring Road that surrounds the outskirts of the city, with exits that reach outer Cairo districts. There are flyovers and bridges, such as the 6th October Bridge that, when the traffic is not heavy, allow fast means of transportation from one side of the city to the other.
Cairo traffic is known to be overwhelming and overcrowded. Traffic moves at a relatively fluid pace. Drivers tend to be aggressive, but are more courteous at junctions, taking turns going, with police aiding in traffic control of some congested areas.
President Mubarak inaugurated the new Cairo Opera House of the Egyptian National Cultural Centres on 10 October 1988, 17 years after the Royal Opera House had been destroyed by fire. The National Cultural Centre was built with the help of JICA, the Japan International Co-operation Agency and stands as a prominent feature for the Japanese-Egyptian co-operation and the friendship between the two nations.
The Khedivial Opera House, or Royal Opera House, was the original opera house in Cairo. It was dedicated on 1 November 1869 and burned down on 28 October 1971. After the original opera house was destroyed, Cairo was without an opera house for nearly two decades until the opening of the new Cairo Opera House in 1988.
Cairo held its first international film festival 16 August 1976, when the first Cairo International Film Festival was launched by the Egyptian Association of Film Writers and Critics, headed by Kamal El-Mallakh. The Association ran the festival for seven years until 1983.
This achievement lead to the President of the Festival again contacting the FIAPF with the request that a competition should be included at the 1991 Festival. The request was granted.
In 1998, the Festival took place under the presidency of one of Egypt's leading actors, Hussein Fahmy, who was appointed by the Minister of Culture, Farouk Hosni, after the death of Saad El-Din Wahba. Four years later, the journalist and writer Cherif El-Shoubashy became president.
The Cairo Geniza is an accumulation of almost 200,000 Jewish manuscripts that were found in the genizah of the Ben Ezra synagogue (built 882) of Fustat, Egypt (now Old Cairo), the Basatin cemetery east of Old Cairo, and a number of old documents that were bought in Cairo in the later 19th century. These documents were written from about 870 to 1880 AD and have been archived in various American and European libraries. The Taylor-Schechter collection in the University of Cambridge runs to 140,000 manuscripts; a further 40,000 manuscripts are housed at the Jewish Theological Seminary of America.
The majority of Cairenes make food for themselves and make use of local produce markets. The restaurant scene includes Arab cuisine and Middle Eastern cuisine, including local staples such as koshary. The city's most exclusive restaurants are typically concentrated in Zamalek and around the luxury hotels lining the shore of the Nile near the Garden City district. Influence from modern western society is also evident, with American chains such as McDonald's, Arby's, Pizza Hut, Subway, and Kentucky Fried Chicken being easy to find in central areas.
Football is the most popular sport in Egypt, and Cairo has a number of sporting teams that compete in national and regional leagues, most notably Al Ahly and Zamalek SC, who are the CAF first and second African clubs of the 20th century. The annual match between Al Ahly and El Zamalek is one of the most watched sports events in Egypt as well as the African-Arab region. The teams form the major rivalry of Egyptian football and are the first and the second champions in Africa and the Arab world. They play their home games at Cairo International Stadium or Naser Stadium, which is the second largest stadium in Egypt, as well as the largest in Cairo and one of the largest stadiums in the world.
The Cairo International Stadium was built in 1960 and its multi-purpose sports complex that houses the main football stadium, an indoor stadium, several satellite fields that held several regional, continental, and global games, including the African Games, U17 Football World Championship and were one of the stadiums scheduled that hosted the 2006 Africa Cup of Nations which was played in January 2006. Egypt later won the competition and went on to win the next edition in Ghana (2008) making the Egyptian and Ghanaian national teams the only teams to win the African Nations Cup Back to back which resulted in Egypt winning the title for a record number of six times in the history of African Continental Competition. This was followed by a third consecutive win in Angola in 2010, making Egypt the only country with a record 3-consecutive and 7-total Continental Football Competition winner. This achievement also placed the Egyptian football team as the #9 best team in the world's FIFA rankings. As of 2021, Egypt's national team is ranked #46 in the world by FIFA.
Cairo failed at the applicant stage when bidding for the 2008 Summer Olympics, which was hosted in Beijing, China. However, Cairo did host the 2007 Pan Arab Games.
There are several other sports teams in the city that participate in several sports including Gezira Sporting Club, el Shams Club, el Seid Club, Heliopolis Sporting Club, and several smaller clubs, but the biggest clubs in Egypt (not in the area but in sports) are Al Ahly and Zamalek. They have the two biggest football teams in Egypt. There are new sports clubs in the area of New Cairo (one hour far from Cairo's downtown), these are Al Zohour sporting club, Wadi Degla sporting club and Platinum Club.
Most of the sports federations of the country are also located in the city suburbs, including the Egyptian Football Association. The headquarters of the Confederation of African Football (CAF) was previously located in Cairo, before relocating to its new headquarters in 6 October City, a small city away from Cairo's crowded districts.
In October 2008, the Egyptian Rugby Federation was officially formed and granted membership into the International Rugby Board.
Egypt is internationally known for the excellence of its squash players who excel in professional and junior divisions. Egypt has seven players in the top ten of the PSA men's world rankings, and three in the women's top ten. Mohamed El Shorbagy held the world number one position for more than a year before being overtaken by compatriot Karim Abdel Gawad, who is number two behind Gregory Gaultier of France. Ramy Ashour and Amr Shabana are regarded as two of the most talented squash players in history. Shabana won the World Open title four times and Ashour twice, although his recent form has been hampered by injury. Egypt's Nour El Sherbini has won the Women's World Championship twice and has been women's world number one for 16 consecutive months. On 30 April 2016, she became the youngest woman to win the Women's World Championship which was held in Malaysia. In April 2017 she retained her title by winning the Women's World Championship which was held in the Egyptian resort of El Gouna.
Cairo is the official end point of Cross Egypt Challenge where its route ends yearly in the most sacred place in Egypt, under the Great Pyramids of Giza with a huge trophy-giving ceremony.
Tahrir Square was founded during the mid 19th century with the establishment of modern downtown Cairo. It was first named Ismailia Square, after the 19th-century ruler Khedive Ismail, who commissioned the new downtown district's 'Paris on the Nile' design. After the Egyptian Revolution of 1919 the square became widely known as Tahrir (Liberation) Square, though it was not officially renamed as such until after the 1952 Revolution which eliminated the monarchy. Several notable buildings surround the square including, the American University in Cairo's downtown campus, the Mogamma governmental administrative Building, the headquarters of the Arab League, the Nile Ritz Carlton Hotel, and the Egyptian Museum. Being at the heart of Cairo, the square witnessed several major protests over the years. However, the most notable event in the square was being the focal point of the 2011 Egyptian Revolution against former president Hosni Mubarak. In 2020 the government completed the erection of a new monument in the center of the square featuring an ancient obelisk from the reign of Ramses II, originally unearthed at Tanis (San al-Hagar) in 2019, and four ram-headed sphinx statues moved from Karnak.
The Museum of Egyptian Antiquities, known commonly as the Egyptian Museum, is home to the most extensive collection of ancient Egyptian antiquities in the world. It has 136,000 items on display, with many more hundreds of thousands in its basement storerooms. Among the collections on display are the finds from the tomb of Tutankhamun.
Much of the collection of the Museum of Egyptian Antiquities, including the Tutankhamun collection, are slated to be moved to the new Grand Egyptian Museum, under construction in Giza and was due to open by the end of 2020.
The Cairo Tower is a free-standing tower with a revolving restaurant at the top. It provides a bird's eye view of Cairo to the restaurant patrons. It stands in the Zamalek district on Gezira Island in the Nile River, in the city centre. At 187 m (614 ft), it is 44 m (144 ft) higher than the Great Pyramid of Giza, which stands some 15 km (9 mi) to the southwest.
This area of Cairo is so-named as it contains the remains of the ancient Roman fortress of Babylon and also overlaps the original site of Fustat, the first Arab settlement in Egypt (7th century AD) and the predecessor of later Cairo. The area includes Coptic Cairo, which holds a high concentration of old Christian churches such as the Hanging Church, the Greek Orthodox Church of St. George, and other Christian or Coptic buildings, most of which are located in an enclave on the site of the ancient Roman fortress. It is also the location of the Coptic Museum, which showcases the history of Coptic art from Greco-Roman to Islamic times, and of the Ben Ezra Synagogue, the oldest and best-known synagogue in Cairo, where the important collection of Geniza documents were discovered in the 19th century.
To the north of this Coptic enclave is the Amr ibn al-'As Mosque, the first mosque in Egypt and the most important religious centre of what was formerly Fustat, founded in 642 AD right after the Arab conquest but rebuilt many times since. A part of the former city of Fustat has also been excavated to the east of the mosque and of the Coptic enclave, although the archeological site is threatened by encroaching construction and modern development. To the northwest of Babylon Fortress and the mosque is the Monastery of Saint Mercurius (or Dayr Abu Sayfayn), an important and historic Coptic religious complex consisting of the Church of Saint Mercurius, the Church of Saint Shenute, and the Church of the Virgin (also known as al-Damshiriya). Several other historic churches are also situated to the south of Babylon Fortress.
Cairo holds one of the greatest concentrations of historical monuments of Islamic architecture in the world. The areas around the old walled city and around the Citadel are characterized by hundreds of mosques, tombs, madrasas, mansions, caravanserais, and fortifications dating from the Islamic era and are often referred to as "Islamic Cairo", especially in English travel literature. It is also the location of several important religious shrines such as the al-Hussein Mosque (whose shrine is believed to hold the head of Husayn ibn Ali), the Mausoleum of Imam al-Shafi'i (founder of the Shafi'i madhhab, one of the primary schools of thought in Sunni Islamic jurisprudence), the Tomb of Sayyida Ruqayya, the Mosque of Sayyida Nafisa, and others.
The first mosque in Egypt was the Mosque of Amr ibn al-As in what was formerly Fustat, the first Arab-Muslim settlement in the area. However, the Mosque of Ibn Tulun is the oldest mosque that still retains its original form and is a rare example of Abbasid architecture from the classical period of Islamic civilization. It was built in 876–879 AD in a style inspired by the Abbasid capital of Samarra in Iraq. It is one of the largest mosques in Cairo and is often cited as one of the most beautiful. Another Abbasid construction, the Nilometer on Roda Island, is the oldest original structure in Cairo, built in 862 AD. It was designed to measure the level of the Nile, which was important for agricultural and administrative purposes.
The settlement that was formally named Cairo (Arabic: al-Qahira) was founded to the northeast of Fustat in 959 AD by the victorious Fatimid army. The Fatimids built it as a separate palatial city which contained their palaces and institutions of government. It was enclosed by a circuit of walls, which were rebuilt in stone in the late 11th century AD by the vizier Badr al-Gamali, parts of which survive today at Bab Zuwayla in the south and Bab al-Futuh and Bab al-Nasr in the north. Among the extant monuments from the Fatimid era are the large Mosque of al-Hakim, the Aqmar Mosque, Juyushi Mosque, Lulua Mosque, and the Mosque of Al-Salih Tala'i.
One of the most important and lasting institutions founded in the Fatimid period was the Mosque of al-Azhar, founded in 970 AD, which competes with the Qarawiyyin in Fes for the title of oldest university in the world. Today, al-Azhar University is the foremost Center of Islamic learning in the world and one of Egypt's largest universities with campuses across the country. The mosque itself retains significant Fatimid elements but has been added to and expanded in subsequent centuries, notably by the Mamluk sultans Qaytbay and al-Ghuri and by Abd al-Rahman Katkhuda in the 18th century.
The most prominent architectural heritage of medieval Cairo, however, dates from the Mamluk period, from 1250 to 1517 AD. The Mamluk sultans and elites were eager patrons of religious and scholarly life, commonly building religious or funerary complexes whose functions could include a mosque, madrasa, khanqah (for Sufis), a sabil (water dispensary), and a mausoleum for themselves and their families. Among the best-known examples of Mamluk monuments in Cairo are the huge Mosque-Madrasa of Sultan Hasan, the Mosque of Amir al-Maridani, the Mosque of Sultan al-Mu'ayyad (whose twin minarets were built above the gate of Bab Zuwayla), the Sultan Al-Ghuri complex, the funerary complex of Sultan Qaytbay in the Northern Cemetery, and the trio of monuments in the Bayn al-Qasrayn area comprising the complex of Sultan al-Mansur Qalawun, the Madrasa of al-Nasir Muhammad, and the Madrasa of Sultan Barquq. Some mosques include spolia (often columns or capitals) from earlier buildings built by the Romans, Byzantines, or Copts.
The Mamluks, and the later Ottomans, also built wikalas or caravanserais to house merchants and goods due to the important role of trade and commerce in Cairo's economy. Still intact today is the Wikala al-Ghuri, which today hosts regular performances by the Al-Tannoura Egyptian Heritage Dance Troupe. The Khan al-Khalili is a commercial hub which also integrated caravanserais (also known as khans).
The Citadel is a fortified enclosure begun by Salah al-Din in 1176 AD on an outcrop of the Muqattam Hills as part of a large defensive system to protect both Cairo to the north and Fustat to the southwest. It was the centre of Egyptian government and residence of its rulers until 1874, when Khedive Isma'il moved to 'Abdin Palace. It is still occupied by the military today, but is now open as a tourist attraction comprising, notably, the National Military Museum, the 14th century Mosque of al-Nasir Muhammad, and the 19th century Mosque of Muhammad Ali which commands a dominant position on Cairo's skyline.
Khan el-Khalili is an ancient bazaar, or marketplace adjacent to the Al-Hussein Mosque. It dates back to 1385, when Amir Jarkas el-Khalili built a large caravanserai, or khan. (A caravanserai is a hotel for traders, and usually the focal point for any surrounding area.) This original caravanserai building was demolished by Sultan al-Ghuri, who rebuilt it as a new commercial complex in the early 16th century, forming the basis for the network of souqs existing today. Many medieval elements remain today, including the ornate Mamluk-style gateways. Today, the Khan el-Khalili is a major tourist attraction and popular stop for tour groups.
In the present day, Cairo is heavily urbanized and most Cairenes live in apartment buildings. Because of the influx of people into the city, lone standing houses are rare, and apartment buildings accommodate for the limited space and abundance of people. Single detached houses are usually owned by the wealthy. Formal education is also seen as important, with twelve years of standard formal education. Cairenes can take a standardized test similar to the SAT to be accepted to an institution of higher learning, but most children do not finish school and opt to pick up a trade to enter the work force. Egypt still struggles with poverty, with almost half the population living on $2 or less a day.
The civil rights movement for women in Cairo – and by extent, Egypt – has been a struggle for years. Women are reported to face constant discrimination, sexual harassment, and abuse throughout Cairo. A 2013 UN study found that over 99% of Egyptian women reported experiencing sexual harassment at some point in their lives. The problem has persisted in spite of new national laws since 2014 defining and criminalizing sexual harassment. The situation is so severe that in 2017, Cairo was named by one poll as the most dangerous megacity for women in the world. In 2020, the social media account "Assault Police" began to name and shame perpetrators of violence against women, in an effort to dissuade potential offenders. The account was founded by student Nadeen Ashraf, who is credited for instigating an iteration of the #MeToo movement in Egypt.
The air pollution in Cairo is a matter of serious concern. Greater Cairo's volatile aromatic hydrocarbon levels are higher than many other similar cities. Air quality measurements in Cairo have also been recording dangerous levels of lead, carbon dioxide, sulphur dioxide, and suspended particulate matter concentrations due to decades of unregulated vehicle emissions, urban industrial operations, and chaff and trash burning. There are over 4,500,000 cars on the streets of Cairo, 60% of which are over 10 years old, and therefore lack modern emission cutting features. Cairo has a very poor dispersion factor because of its lack of rain and its layout of tall buildings and narrow streets, which create a bowl effect.
In recent years, a black cloud (as Egyptians refer to it) of smog has appeared over Cairo every autumn due to temperature inversion. Smog causes serious respiratory diseases and eye irritations for the city's citizens. Tourists who are not familiar with such high levels of pollution must take extra care.
Cairo also has many unregistered lead and copper smelters which heavily pollute the city. The results of this has been a permanent haze over the city with particulate matter in the air reaching over three times normal levels. It is estimated that 10,000 to 25,000 people a year in Cairo die due to air pollution-related diseases. Lead has been shown to cause harm to the central nervous system and neurotoxicity particularly in children. In 1995, the first environmental acts were introduced and the situation has seen some improvement with 36 air monitoring stations and emissions tests on cars. Twenty thousand buses have also been commissioned to the city to improve congestion levels, which are very high.
The city also suffers from a high level of land pollution. Cairo produces 10,000 tons of waste material each day, 4,000 tons of which is not collected or managed. This is a huge health hazard, and the Egyptian Government is looking for ways to combat this. The Cairo Cleaning and Beautification Agency was founded to collect and recycle the waste; they work with the Zabbaleen community that has been collecting and recycling Cairo's waste since the turn of the 20th century and live in an area known locally as Manshiyat naser. Both are working together to pick up as much waste as possible within the city limits, though it remains a pressing problem.
Water pollution is also a serious problem in the city as the sewer system tends to fail and overflow. On occasion, sewage has escaped onto the streets to create a health hazard. This problem is hoped to be solved by a new sewer system funded by the European Union, which could cope with the demand of the city. The dangerously high levels of mercury in the city's water system has global health officials concerned over related health risks.
The Headquarters of the Arab League is located in Tahrir Square, near the downtown business district of Cairo.
Cairo is twinned with: | [
{
"paragraph_id": 0,
"text": "Cairo (/ˈkaɪroʊ/ KY-roh; Arabic: القاهرة, romanized: al-Qāhirah, pronounced [ælqɑ(ː)ˈheɾɑ] ) is the capital of Egypt and the city-state Cairo Governorate, and is the country's largest city, home to 10 million people. It is also part of the largest urban agglomeration in Africa, the Arab world and the Middle East: The Greater Cairo metropolitan area is the 12th-largest in the world by population with a population of over 22.1 million.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Cairo is associated with ancient Egypt, as the Giza pyramid complex and the ancient cities of Memphis and Heliopolis are located in its geographical area. Located near the Nile Delta, the city first developed as Fustat following the Muslim conquest of Egypt in 641 next to an existing ancient Roman fortress, Babylon. Cairo was founded by the Fatimid dynasty in 969. It later superseded Fustat as the main urban centre during the Ayyubid and Mamluk periods (12th–16th centuries). Cairo has long been a centre of the region's political and cultural life, and is titled \"the city of a thousand minarets\" for its preponderance of Islamic architecture. Cairo's historic center was awarded World Heritage Site status in 1979. Cairo is considered a World City with a \"Beta +\" classification according to GaWC.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Cairo has the oldest and largest film and music industry in the Arab world, as well as Egypt's oldest institution of higher learning, Al-Azhar University. Many international media, businesses, and organizations have regional headquarters in the city; the Arab League has had its headquarters in Cairo for most of its existence.",
"title": ""
},
{
"paragraph_id": 3,
"text": "With a population of over 10 million spread over 453 km (175 sq mi), Cairo is by far the largest city in Egypt. An additional 9.5 million inhabitants live close to the city. Cairo, like many other megacities, suffers from high levels of pollution and traffic. The Cairo Metro, opened in 1987, is the oldest metro system in Africa, and ranks amongst the fifteen busiest in the world, with over 1 billion annual passenger rides. The economy of Cairo was ranked first in the Middle East in 2005, and 43rd globally on Foreign Policy's 2010 Global Cities Index.",
"title": ""
},
{
"paragraph_id": 4,
"text": "The name Cairo is derived from the Arabic al-Qāhirah (القاهرة), meaning 'the Vanquisher' or 'the Conqueror', given by the Fatimid Caliph al-Mu'izz following the establishment of the city as the capital of the Fatimid dynasty. Initially, its full name was Qāhirat al-Mu'izz, meaning 'the Vanquisher of al-Mu'izz'. It is also supposedly due to the fact that the planet Mars, known in Arabic by names such as an-Najm al-Qāhir (النجم القاهر, 'the Conquering Star'), was rising at the time of the city's founding.",
"title": "Etymology"
},
{
"paragraph_id": 5,
"text": "Egyptians often refer to Cairo as Maṣr (IPA: [mɑsˤɾ]; مَصر), the Egyptian Arabic name for Egypt itself, emphasizing the city's importance for the country.",
"title": "Etymology"
},
{
"paragraph_id": 6,
"text": "There are a number of Coptic names for the city. Tikešrōmi (Coptic: Ϯⲕⲉϣⲣⲱⲙⲓ Late Coptic: [di.kɑʃˈɾoːmi]) is attested in the 1211 text The Martyrdom of John of Phanijoit and is either a calque meaning 'man breaker' (Ϯ-, 'the', ⲕⲁϣ-, 'to break', and ⲣⲱⲙⲓ, 'man'), akin to Arabic al-Qāhirah, or a derivation from Arabic قَصْر الرُوم (qaṣr ar-rūm, \"the Roman castle\"), another name of Babylon Fortress in Old Cairo. The Arabic name is also calqued as ⲧⲡⲟⲗⲓⲥ ϯⲣⲉϥϭⲣⲟ, \"the victor city\" in the Coptic antiphonary.",
"title": "Etymology"
},
{
"paragraph_id": 7,
"text": "The form Khairon (Coptic: ⲭⲁⲓⲣⲟⲛ) is attested in the modern Coptic text Ⲡⲓⲫⲓⲣⲓ ⲛ̀ⲧⲉ ϯⲁⲅⲓⲁ ⲙ̀ⲙⲏⲓ Ⲃⲉⲣⲏⲛⲁ (The Tale of Saint Verina). Lioui (Ⲗⲓⲟⲩⲓ Late Coptic: [lɪˈjuːj]) or Elioui (Ⲉⲗⲓⲟⲩⲓ Late Coptic: [ælˈjuːj]) is another name which is descended from the Greek name of Heliopolis (Ήλιούπολις). Some argue that Mistram (Ⲙⲓⲥⲧⲣⲁⲙ Late Coptic: [ˈmɪs.təɾɑm]) or Nistram (Ⲛⲓⲥⲧⲣⲁⲙ Late Coptic: [ˈnɪs.təɾɑm]) is another Coptic name for Cairo, although others think that it is rather a name for the Abbasid province capital al-Askar. Ⲕⲁϩⲓⲣⲏ (Kahi•ree) is a popular modern rendering of an Arabic name (others being Ⲕⲁⲓⲣⲟⲛ [Kairon] and Ⲕⲁϩⲓⲣⲁ [Kahira]) which is modern folk etymology meaning 'land of sun'. Some argue that it was a name of an Egyptian settlement upon which Cairo was built, but it is rather doubtful as this name is not attested in any Hieroglyphic or Demotic source, although some researchers, like Paul Casanova, view it as a legitimate theory. Cairo is also referred to as Ⲭⲏⲙⲓ (Late Coptic: [ˈkɪ.mi]) or Ⲅⲩⲡⲧⲟⲥ (Late Coptic: [ˈɡɪp.dos]), which means Egypt in Coptic, the same way it is referred to in Egyptian Arabic.",
"title": "Etymology"
},
{
"paragraph_id": 8,
"text": "Sometimes the city is informally referred to as Cairo by people from Alexandria (IPA: [ˈkæjɾo]; Egyptian Arabic: كايرو).",
"title": "Etymology"
},
{
"paragraph_id": 9,
"text": "The area around present-day Cairo had long been a focal point of Ancient Egypt due to its strategic location at the junction of the Nile Valley and the Nile Delta regions (roughly Upper Egypt and Lower Egypt), which also placed it at the crossing of major routes between North Africa and the Levant. Memphis, the capital of Egypt during the Old Kingdom and a major city up until the Ptolemaic period, was located a short distance south west of present-day Cairo. Heliopolis, another important city and major religious center, was located in what are now the modern districts of Matariya and Ain Shams in northeastern Cairo. It was largely destroyed by the Persian invasions in 525 BC and 343 BC and partly abandoned by the late first century BC.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "However, the origins of modern Cairo are generally traced back to a series of settlements in the first millennium AD. Around the turn of the fourth century, as Memphis was continuing to decline in importance, the Romans established a large fortress along the east bank of the Nile. The fortress, called Babylon, was built by the Roman emperor Diocletian (r. 285–305) at the entrance of a canal connecting the Nile to the Red Sea that was created earlier by emperor Trajan (r. 98–115). Further north of the fortress, near the present-day district of al-Azbakiya, was a port and fortified outpost known as Tendunyas (Coptic: ϯⲁⲛⲧⲱⲛⲓⲁⲥ) or Umm Dunayn. While no structures older than the 7th century have been preserved in the area aside from the Roman fortifications, historical evidence suggests that a sizeable city existed. The city was important enough that its bishop, Cyrus, participated in the Second Council of Ephesus in 449.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "The Byzantine-Sassanian War between 602 and 628 caused great hardship and likely caused much of the urban population to leave for the countryside, leaving the settlement partly deserted. The site today remains at the nucleus of the Coptic Orthodox community, which separated from the Roman and Byzantine churches in the late 4th century. Cairo's oldest extant churches, such as the Church of Saint Barbara and the Church of Saints Sergius and Bacchus (from the late 7th or early 8th century), are located inside the fortress walls in what is now known as Old Cairo or Coptic Cairo.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "The Muslim conquest of Byzantine Egypt was led by Amr ibn al-As from 639 to 642. Babylon Fortress was besieged in September 640 and fell in April 641. In 641 or early 642, after the surrender of Alexandria (the Egyptian capital at the time), he founded a new settlement next to Babylon Fortress. The city, known as Fustat (Arabic: الفسطاط, romanized: al-Fusṭāṭ, lit. 'the tent'), served as a garrison town and as the new administrative capital of Egypt. Historians such as Janet Abu-Lughod and André Raymond trace the genesis of present-day Cairo to the foundation of Fustat. The choice of founding a new settlement at this inland location, instead of using the existing capital of Alexandria on the Mediterranean coast, may have been due to the new conquerors' strategic priorities. One of the first projects of the new Muslim administration was to clear and re-open Trajan's ancient canal in order to ship grain more directly from Egypt to Medina, the capital of the caliphate in Arabia. Ibn al-As also founded a mosque for the city at the same time, now known as the Mosque of Amr Ibn al-As, the oldest mosque in Egypt and Africa (although the current structure dates from later expansions).",
"title": "History"
},
{
"paragraph_id": 13,
"text": "In 750, following the overthrow of the Umayyad caliphate by the Abbasids, the new rulers created their own settlement to the northeast of Fustat which became the new provincial capital. This was known as al-Askar (Arabic: العسكر, lit. 'the camp') as it was laid out like a military camp. A governor's residence and a new mosque were also added, with the latter completed in 786. In 861, on the orders of the Abbasid caliph al-Mutawakkil, a Nilometer was built on Roda Island near Fustat. Although it was repaired and given a new roof in later centuries, its basic structure is still preserved today, making it the oldest preserved Islamic-era structure in Cairo today.",
"title": "History"
},
{
"paragraph_id": 14,
"text": "In 868 a commander of Turkic origin named Bakbak was sent to Egypt by the Abbasid caliph al-Mu'taz to restore order after a rebellion in the country. He was accompanied by his stepson, Ahmad ibn Tulun, who became effective governor of Egypt. Over time, Ibn Tulun gained an army and accumulated influence and wealth, allowing him to become the de facto independent ruler of both Egypt and Syria by 878. In 870, he used his growing wealth to found a new administrative capital, al-Qata'i (Arabic: القطائـع, lit. 'the allotments'), to the northeast of Fustat and of al-Askar. The new city included a palace known as the Dar al-Imara, a parade ground known as al-Maydan, a bimaristan (hospital), and an aqueduct to supply water. Between 876 and 879 Ibn Tulun built a great mosque, now known as the Mosque of Ibn Tulun, at the center of the city, next to the palace. After his death in 884, Ibn Tulun was succeeded by his son and his descendants who continued a short-lived dynasty, the Tulunids. In 905, the Abbasids sent general Muhammad Sulayman al-Katib to re-assert direct control over the country. Tulunid rule was ended and al-Qatta'i was razed to the ground, except for the mosque which remains standing today.",
"title": "History"
},
{
"paragraph_id": 15,
"text": "In 969, the Shi'a Isma'ili Fatimid empire conquered Egypt after ruling from Ifriqiya. The Fatimid general Jawhar Al Saqili founded a new fortified city northeast of Fustat and of former al-Qata'i. It took four years to build the city, initially known as al-Manṣūriyyah, which was to serve as the new capital of the caliphate. During that time, the construction of the al-Azhar Mosque was commissioned by order of the caliph, which developed into the third-oldest university in the world. Cairo would eventually become a centre of learning, with the library of Cairo containing hundreds of thousands of books. When Caliph al-Mu'izz li Din Allah arrived from the old Fatimid capital of Mahdia in Tunisia in 973, he gave the city its present name, Qāhirat al-Mu'izz (\"The Vanquisher of al-Mu'izz\"), from which the name \"Cairo\" (al-Qāhira) originates. The caliphs lived in a vast and lavish palace complex that occupied the heart of the city. Cairo remained a relatively exclusive royal city for most of this era, but during the tenure of Badr al-Gamali as vizier (1073–1094) the restrictions were loosened for the first time and richer families from Fustat were allowed to move into the city. Between 1087 and 1092 Badr al-Gamali also rebuilt the city walls in stone and constructed the city gates of Bab al-Futuh, Bab al-Nasr, and Bab Zuweila that still stand today.",
"title": "History"
},
{
"paragraph_id": 16,
"text": "During the Fatimid period Fustat reached its apogee in size and prosperity, acting as a center of craftsmanship and international trade and as the area's main port on the Nile. Historical sources report that multi-story communal residences existed in the city, particularly in its center, which were typically inhabited by middle and lower-class residents. Some of these were as high as seven stories and could house some 200 to 350 people. They may have been similar to Roman insulae and may have been the prototypes for the rental apartment complexes which became common in the later Mamluk and Ottoman periods.",
"title": "History"
},
{
"paragraph_id": 17,
"text": "However, in 1168 the Fatimid vizier Shawar set fire to unfortified Fustat to prevent its potential capture by Amalric, the Crusader king of Jerusalem. While the fire did not destroy the city and it continued to exist afterward, it did mark the beginning of its decline. Over the following centuries it was Cairo, the former palace-city, that became the new economic center and attracted migration from Fustat.",
"title": "History"
},
{
"paragraph_id": 18,
"text": "While the Crusaders did not capture the city in 1168, a continuing power struggle between Shawar, King Amalric, and the Zengid general Shirkuh led to the downfall of the Fatimid establishment. In 1169, Shirkuh's nephew Saladin was appointed as the new vizier of Egypt by the Fatimids and two years later he seized power from the family of the last Fatimid caliph, al-'Āḍid. As the first Sultan of Egypt, Saladin established the Ayyubid dynasty, based in Cairo, and aligned Egypt with the Sunni Abbasids, who were based in Baghdad. In 1176, Saladin began construction on the Cairo Citadel, which was to serve as the seat of the Egyptian government until the mid-19th century. The construction of the Citadel definitively ended Fatimid-built Cairo's status as an exclusive palace-city and opened it up to common Egyptians and to foreign merchants, spurring its commercial development. Along with the Citadel, Saladin also began the construction of a new 20-kilometre-long wall that would protect both Cairo and Fustat on their eastern side and connect them with the new Citadel. These construction projects continued beyond Saladin's lifetime and were completed under his Ayyubid successors.",
"title": "History"
},
{
"paragraph_id": 19,
"text": "In 1250, during the Seventh Crusade, the Ayyubid dynasty had a crisis with the death of al-Salih and power transitioned instead to the Mamluks, partly with the help of al-Salih's wife, Shajar ad-Durr, who ruled for a brief period around this time. Mamluks were soldiers who were purchased as young slaves and raised to serve in the sultan's army. Between 1250 and 1517 the throne of the Mamluk Sultanate passed from one mamluk to another in a system of succession that was generally non-hereditary, but also frequently violent and chaotic. The Mamluk Empire nonetheless became a major power in the region and was responsible for repelling the advance of the Mongols (most famously at the Battle of Ain Jalut in 1260) and for eliminating the last Crusader states in the Levant.",
"title": "History"
},
{
"paragraph_id": 20,
"text": "Despite their military character, the Mamluks were also prolific builders and left a rich architectural legacy throughout Cairo. Continuing a practice started by the Ayyubids, much of the land occupied by former Fatimid palaces was sold and replaced by newer buildings, becoming a prestigious site for the construction of Mamluk religious and funerary complexes. Construction projects initiated by the Mamluks pushed the city outward while also bringing new infrastructure to the centre of the city. Meanwhile, Cairo flourished as a centre of Islamic scholarship and a crossroads on the spice trade route among the civilisations in Afro-Eurasia. Under the reign of the Mamluk sultan al-Nasir Muhammad (1293–1341, with interregnums), Cairo reached its apogee in terms of population and wealth. By 1340, Cairo had a population of close to half a million, making it the largest city west of China.",
"title": "History"
},
{
"paragraph_id": 21,
"text": "Multi-story buildings occupied by rental apartments, known as a rab' (plural ribā' or urbu), became common in the Mamluk period and continued to be a feature of the city's housing during the later Ottoman period. These apartments were often laid out as multi-story duplexes or triplexes. They were sometimes attached to caravanserais, where the two lower floors were for commercial and storage purposes and the multiple stories above them were rented out to tenants. The oldest partially-preserved example of this type of structure is the Wikala of Amir Qawsun, built before 1341. Residential buildings were in turn organized into close-knit neighbourhoods called a harat, which in many cases had gates that could be closed off at night or during disturbances.",
"title": "History"
},
{
"paragraph_id": 22,
"text": "When the traveller Ibn Battuta first came to Cairo in 1326, he described it as the principal district of Egypt. When he passed through the area again on his return journey in 1348 the Black Death was ravaging most major cities. He cited reports of thousands of deaths per day in Cairo. Although Cairo avoided Europe's stagnation during the Late Middle Ages, it could not escape the Black Death, which struck the city more than fifty times between 1348 and 1517. During its initial, and most deadly waves, approximately 200,000 people were killed by the plague, and, by the 15th century, Cairo's population had been reduced to between 150,000 and 300,000. The population decline was accompanied by a period of political instability between 1348 and 1412. It was nonetheless in this period that the largest Mamluk-era religious monument, the Madrasa-Mosque of Sultan Hasan, was built. In the late 14th century the Burji Mamluks replaced the Bahri Mamluks as rulers of the Mamluk state, but the Mamluk system continued to decline.",
"title": "History"
},
{
"paragraph_id": 23,
"text": "Though the plagues returned frequently throughout the 15th century, Cairo remained a major metropolis and its population recovered in part through rural migration. More conscious efforts were conducted by rulers and city officials to redress the city's infrastructure and cleanliness. Its economy and politics also became more deeply connected with the wider Mediterranean. Some Mamluk sultans in this period, such as Barbsay (r. 1422–1438) and Qaytbay (r. 1468–1496), had relatively long and successful reigns. After al-Nasir Muhammad, Qaytbay was one of the most prolific patrons of art and architecture of the Mamluk era. He built or restored numerous monuments in Cairo, in addition to commissioning projects beyond Egypt. The crisis of Mamluk power and of Cairo's economic role deepened after Qaytbay. The city's status was diminished after Vasco da Gama discovered a sea route around the Cape of Good Hope between 1497 and 1499, thereby allowing spice traders to avoid Cairo.",
"title": "History"
},
{
"paragraph_id": 24,
"text": "Cairo's political influence diminished significantly after the Ottomans defeated Sultan al-Ghuri in the Battle of Marj Dabiq in 1516 and conquered Egypt in 1517. Ruling from Constantinople, Sultan Selim I relegated Egypt to a province, with Cairo as its capital. For this reason, the history of Cairo during Ottoman times is often described as inconsequential, especially in comparison to other time periods.",
"title": "History"
},
{
"paragraph_id": 25,
"text": "During the 16th and 17th centuries, Cairo still remained an important economic and cultural centre. Although no longer on the spice route, the city facilitated the transportation of Yemeni coffee and Indian textiles, primarily to Anatolia, North Africa, and the Balkans. Cairene merchants were instrumental in bringing goods to the barren Hejaz, especially during the annual hajj to Mecca. It was during this same period that al-Azhar University reached the predominance among Islamic schools that it continues to hold today; pilgrims on their way to hajj often attested to the superiority of the institution, which had become associated with Egypt's body of Islamic scholars. The first printing press of the Middle East, printing in Hebrew, was established in Cairo c. 1557 by a scion of the Soncino family of printers, Italian Jews of Ashkenazi origin who operated a press in Constantinople. The existence of the press is known solely from two fragments discovered in the Cairo Geniza.",
"title": "History"
},
{
"paragraph_id": 26,
"text": "Under the Ottomans, Cairo expanded south and west from its nucleus around the Citadel. The city was the second-largest in the empire, behind Constantinople, and, although migration was not the primary source of Cairo's growth, twenty percent of its population at the end of the 18th century consisted of religious minorities and foreigners from around the Mediterranean. Still, when Napoleon arrived in Cairo in 1798, the city's population was less than 300,000, forty percent lower than it was at the height of Mamluk—and Cairene—influence in the mid-14th century.",
"title": "History"
},
{
"paragraph_id": 27,
"text": "The French occupation was short-lived as British and Ottoman forces, including a sizeable Albanian contingent, recaptured the country in 1801. Cairo itself was besieged by a British and Ottoman force culminating with the French surrender on 22 June 1801. The British vacated Egypt two years later, leaving the Ottomans, the Albanians, and the long-weakened Mamluks jostling for control of the country. Continued civil war allowed an Albanian named Muhammad Ali Pasha to ascend to the role of commander and eventually, with the approval of the religious establishment, viceroy of Egypt in 1805.",
"title": "History"
},
{
"paragraph_id": 28,
"text": "Until his death in 1848, Muhammad Ali Pasha instituted a number of social and economic reforms that earned him the title of founder of modern Egypt. However, while Muhammad Ali initiated the construction of public buildings in the city, those reforms had minimal effect on Cairo's landscape. Bigger changes came to Cairo under Isma'il Pasha (r. 1863–1879), who continued the modernisation processes started by his grandfather. Drawing inspiration from Paris, Isma'il envisioned a city of maidans and wide avenues; due to financial constraints, only some of them, in the area now composing Downtown Cairo, came to fruition. Isma'il also sought to modernize the city, which was merging with neighbouring settlements, by establishing a public works ministry, bringing gas and lighting to the city, and opening a theatre and opera house.",
"title": "History"
},
{
"paragraph_id": 29,
"text": "The immense debt resulting from Isma'il's projects provided a pretext for increasing European control, which culminated with the British invasion in 1882. The city's economic centre quickly moved west toward the Nile, away from the historic Islamic Cairo section and toward the contemporary, European-style areas built by Isma'il. Europeans accounted for five percent of Cairo's population at the end of the 19th century, by which point they held most top governmental positions.",
"title": "History"
},
{
"paragraph_id": 30,
"text": "In 1906 the Heliopolis Oasis Company headed by the Belgian industrialist Édouard Empain and his Egyptian counterpart Boghos Nubar, built a suburb called Heliopolis (city of the sun in Greek) ten kilometers from the center of Cairo. In 1905–1907 the northern part of the Gezira island was developed by the Baehler Company into Zamalek, which would later become Cairo's upscale \"chic\" neighbourhood. In 1906 construction began on Garden City, a neighbourhood of urban villas with gardens and curved streets.",
"title": "History"
},
{
"paragraph_id": 31,
"text": "The British occupation was intended to be temporary, but it lasted well into the 20th century. Nationalists staged large-scale demonstrations in Cairo in 1919, five years after Egypt had been declared a British protectorate. Nevertheless, this led to Egypt's independence in 1922.",
"title": "History"
},
{
"paragraph_id": 32,
"text": "The King Fuad I Edition of the Qur'an was first published on 10 July 1924 in Cairo under the patronage of King Fuad. The goal of the government of the newly formed Kingdom of Egypt was not to delegitimize the other variant Quranic texts (\"qira'at\"), but to eliminate errors found in Qur'anic texts used in state schools. A committee of teachers chose to preserve a single one of the canonical qira'at \"readings\", namely that of the \"Ḥafṣ\" version, an 8th-century Kufic recitation. This edition has become the standard for modern printings of the Quran for much of the Islamic world. The publication has been called a \"terrific success\", and the edition has been described as one \"now widely seen as the official text of the Qur'an\", so popular among both Sunni and Shi'a that the common belief among less well-informed Muslims is \"that the Qur'an has a single, unambiguous reading\". Minor amendments were made later in 1924 and in 1936 - the \"Faruq edition\" in honour of then ruler, King Faruq.",
"title": "History"
},
{
"paragraph_id": 33,
"text": "British troops remained in the country until 1956. During this time, urban Cairo, spurred by new bridges and transport links, continued to expand to include the upscale neighbourhoods of Garden City, Zamalek, and Heliopolis. Between 1882 and 1937, the population of Cairo more than tripled—from 347,000 to 1.3 million—and its area increased from 10 to 163 km (4 to 63 sq mi).",
"title": "History"
},
{
"paragraph_id": 34,
"text": "The city was devastated during the 1952 riots known as the Cairo Fire or Black Saturday, which saw the destruction of nearly 700 shops, movie theatres, casinos and hotels in downtown Cairo. The British departed Cairo following the Egyptian Revolution of 1952, but the city's rapid growth showed no signs of abating. Seeking to accommodate the increasing population, President Gamal Abdel Nasser redeveloped Tahrir Square and the Nile Corniche, and improved the city's network of bridges and highways. Meanwhile, additional controls of the Nile fostered development within Gezira Island and along the city's waterfront. The metropolis began to encroach on the fertile Nile Delta, prompting the government to build desert satellite towns and devise incentives for city-dwellers to move to them.",
"title": "History"
},
{
"paragraph_id": 35,
"text": "In the second half of the 20th century Cairo continue to grow enormously in both population and area. Between 1947 and 2006 the population of Greater Cairo went from 2,986,280 to 16,292,269. The population explosion also drove the rise of \"informal\" housing ('ashwa'iyyat), meaning housing that was built without any official planning or control. The exact form of this type of housing varies considerably but usually has a much higher population density than formal housing. By 2009, over 63% of the population of Greater Cairo lived in informal neighbourhoods, even though these occupied only 17% of the total area of Greater Cairo. According to economist David Sims, informal housing has the benefits of providing affordable accommodation and vibrant communities to huge numbers of Cairo's working classes, but it also suffers from government neglect, a relative lack of services, and overcrowding.",
"title": "History"
},
{
"paragraph_id": 36,
"text": "The \"formal\" city was also expanded. The most notable example was the creation of Madinat Nasr, a huge government-sponsored expansion of the city to the east which officially began in 1959 but was primarily developed in the mid-1970s. Starting in 1977 the Egyptian government established the New Urban Communities Authority to initiate and direct the development of new planned cities on the outskirts of Cairo, generally established on desert land. These new satellite cities were intended to provide housing, investment, and employment opportunities for the region's growing population as well as to pre-empt the further growth of informal neighbourhoods. As of 2014, about 10% of the population of Greater Cairo lived in the new cities.",
"title": "History"
},
{
"paragraph_id": 37,
"text": "Concurrently, Cairo established itself as a political and economic hub for North Africa and the Arab world, with many multinational businesses and organisations, including the Arab League, operating out of the city. In 1979 the historic districts of Cairo were listed as a UNESCO World Heritage Site.",
"title": "History"
},
{
"paragraph_id": 38,
"text": "In 1992, Cairo was hit by an earthquake causing 545 deaths, injuring 6,512 and leaving around 50,000 people homeless.",
"title": "History"
},
{
"paragraph_id": 39,
"text": "Cairo's Tahrir Square was the focal point of the 2011 Egyptian Revolution against former president Hosni Mubarak. Over 2 million protesters were at Cairo's Tahrir square. More than 50,000 protesters first occupied the square on 25 January, during which the area's wireless services were reported to be impaired. In the following days Tahrir Square continued to be the primary destination for protests in Cairo as it took place following a popular uprising that began on Tuesday, 25 January 2011 and continued until June 2013. The uprising was mainly a campaign of non-violent civil resistance, which featured a series of demonstrations, marches, acts of civil disobedience, and labour strikes. Millions of protesters from a variety of socio-economic and religious backgrounds demanded the overthrow of the regime of Egyptian President Hosni Mubarak. Despite being predominantly peaceful in nature, the revolution was not without violent clashes between security forces and protesters, with at least 846 people killed and 6,000 injured. The uprising took place in Cairo, Alexandria, and in other cities in Egypt, following the Tunisian revolution that resulted in the overthrow of the long-time Tunisian president Zine El Abidine Ben Ali. On 11 February, following weeks of determined popular protest and pressure, Hosni Mubarak resigned from office.",
"title": "History"
},
{
"paragraph_id": 40,
"text": "Under the rule of President el-Sisi, in March 2015 plans were announced for another yet-unnamed planned city to be built further east of the existing satellite city of New Cairo, intended to serve as the new capital of Egypt.",
"title": "History"
},
{
"paragraph_id": 41,
"text": "Cairo is located in northern Egypt, known as Lower Egypt, 165 km (100 mi) south of the Mediterranean Sea and 120 km (75 mi) west of the Gulf of Suez and Suez Canal. The city lies along the Nile River, immediately south of the point where the river leaves its desert-bound valley and branches into the low-lying Nile Delta region. Although the Cairo metropolis extends away from the Nile in all directions, the city of Cairo resides only on the east bank of the river and two islands within it on a total area of 453 km (175 sq mi). Geologically, Cairo lies on alluvium and sand dunes which date from the quaternary period.",
"title": "Geography"
},
{
"paragraph_id": 42,
"text": "Until the mid-19th century, when the river was tamed by dams, levees, and other controls, the Nile in the vicinity of Cairo was highly susceptible to changes in course and surface level. Over the years, the Nile gradually shifted westward, providing the site between the eastern edge of the river and the Mokattam highlands on which the city now stands. The land on which Cairo was established in 969 (present-day Islamic Cairo) was located underwater just over three hundred years earlier, when Fustat was first built.",
"title": "Geography"
},
{
"paragraph_id": 43,
"text": "Low periods of the Nile during the 11th century continued to add to the landscape of Cairo; a new island, known as Geziret al-Fil, first appeared in 1174, but eventually became connected to the mainland. Today, the site of Geziret al-Fil is occupied by the Shubra district. The low periods created another island at the turn of the 14th century that now composes Zamalek and Gezira. Land reclamation efforts by the Mamluks and Ottomans further contributed to expansion on the east bank of the river.",
"title": "Geography"
},
{
"paragraph_id": 44,
"text": "Because of the Nile's movement, the newer parts of the city—Garden City, Downtown Cairo, and Zamalek—are located closest to the riverbank. The areas, which are home to most of Cairo's embassies, are surrounded on the north, east, and south by the older parts of the city. Old Cairo, located south of the centre, holds the remnants of Fustat and the heart of Egypt's Coptic Christian community, Coptic Cairo. The Boulaq district, which lies in the northern part of the city, was born out of a major 16th-century port and is now a major industrial centre. The Citadel is located east of the city centre around Islamic Cairo, which dates back to the Fatimid era and the foundation of Cairo. While western Cairo is dominated by wide boulevards, open spaces, and modern architecture of European influence, the eastern half, having grown haphazardly over the centuries, is dominated by small lanes, crowded tenements, and Islamic architecture.",
"title": "Geography"
},
{
"paragraph_id": 45,
"text": "Northern and extreme eastern parts of Cairo, which include satellite towns, are among the most recent additions to the city, as they developed in the late-20th and early-21st centuries to accommodate the city's rapid growth. The western bank of the Nile is commonly included within the urban area of Cairo, but it composes the city of Giza and the Giza Governorate. Giza city has also undergone significant expansion over recent years, and today has a population of 2.7 million. The Cairo Governorate was just north of the Helwan Governorate from 2008 when some Cairo's southern districts, including Maadi and New Cairo, were split off and annexed into the new governorate, to 2011 when the Helwan Governorate was reincorporated into the Cairo Governorate.",
"title": "Geography"
},
{
"paragraph_id": 46,
"text": "According to the World Health Organization, the level of air pollution in Cairo is nearly 12 times higher than the recommended safety level.",
"title": "Geography"
},
{
"paragraph_id": 47,
"text": "In Cairo, and along the Nile River Valley, the climate is a hot desert climate (BWh according to the Köppen climate classification system). Wind storms can be frequent, bringing Saharan dust into the city, from March to May and the air often becomes uncomfortably dry. High temperatures in winter range from 14 to 22 °C (57 to 72 °F), while night-time lows drop to below 11 °C (52 °F), often to 5 °C (41 °F). In summer, the highs rarely surpass 40 °C (104 °F), and lows drop to about 20 °C (68 °F). Rainfall is sparse and only happens in the colder months, but sudden showers can cause severe flooding. The summer months have high humidity due to its coastal location. Snowfall is extremely rare; a small amount of graupel, widely believed to be snow, fell on Cairo's easternmost suburbs on 13 December 2013, the first time Cairo's area received this kind of precipitation in many decades. Dew points in the hottest months range from 13.9 °C (57 °F) in June to 18.3 °C (65 °F) in August.",
"title": "Geography"
},
{
"paragraph_id": 48,
"text": "The city of Cairo forms part of Greater Cairo, the largest metropolitan area in Africa. While it has no administrative body, the Ministry of Planning considers it as an economic region consisting of Cairo Governorate, Giza Governorate, and Qalyubia Governorate. As a contiguous metropolitan area, various studies have considered Greater Cairo be composed of the administrative cities that are Cairo, Giza and Shubra al-Kheima, in addition to the satellite cities/new towns surrounding them.",
"title": "Geography"
},
{
"paragraph_id": 49,
"text": "Cairo is a city-state where the governor is also the head of the city. Cairo City itself differs from other Egyptian cities in that it has an extra administrative division between the city and district levels, and that is areas, which are headed by deputy governors. Cairo consists of 4 areas (manatiq, singl. mantiqa) divided into 38 districts (ahya', singl. hayy) and 46 qisms (police wards, 1-2 per district):",
"title": "Geography"
},
{
"paragraph_id": 50,
"text": "The Northern Area is divided into 8 Districts:",
"title": "Geography"
},
{
"paragraph_id": 51,
"text": "The Eastern Area divided into 9 Districts and three new cities:",
"title": "Geography"
},
{
"paragraph_id": 52,
"text": "The Western Area divided into 9 Districts:",
"title": "Geography"
},
{
"paragraph_id": 53,
"text": "The Southern Area divided into 12 Districts:",
"title": "Geography"
},
{
"paragraph_id": 54,
"text": "Since 1977 a number of new towns have been planned and built by the New Urban Communities Authority (NUCA) in the Eastern Desert around Cairo, ostensibly to accommodate additional population growth and development of the city and stem the development of self-built informal areas, especially over agricultural land. As of 2022 four new towns have been built and have residential populations: 15th of May City, Badr City, Shorouk City, and New Cairo. In addition, two more are under construction: the New Administrative Capital. And Capital Gardens, where land was allocated in 2021, and which will house most of the civil servants employed in the new capital.",
"title": "Geography"
},
{
"paragraph_id": 55,
"text": "In March 2015, plans were announced for a new city to be built east of Cairo, in an undeveloped area of the Cairo Governorate, which would serve as the New Administrative Capital of Egypt.",
"title": "Geography"
},
{
"paragraph_id": 56,
"text": "According to the 2017 census, Cairo had a population of 9,539,673 people, distributed across 46 qisms (police wards):",
"title": "Demographics"
},
{
"paragraph_id": 57,
"text": "The majority of Egypt and Cairo's population is Sunni Muslim. A significant Christian minority exists, among whom Coptic Orthodox are the majority. Precise numbers for each religious community in Egypt are not available and estimates vary. Other churches that have, or had, a presence in modern Cairo include the Catholic Church (including Armenian Catholic, Coptic Catholic, Chaldean Catholic, Syrian Catholic, and Maronite), the Greek Orthodox Church, the Evangelical Church of Egypt (Synod of the Nile), and some Protestant churches. Until the 20th century, Cairo had a sizeable Jewish community, but as of 2022 only 3 Jews were reported to be living in the city. A total of 12 synagogues in Cairo still exist.",
"title": "Demographics"
},
{
"paragraph_id": 58,
"text": "Cairo's economy has traditionally been based on governmental institutions and services, with the modern productive sector expanding in the 20th century to include developments in textiles and food processing – specifically the production of sugar cane. As of 2005, Egypt has the largest non-oil based GDP in the Arab world.",
"title": "Economy"
},
{
"paragraph_id": 59,
"text": "Cairo accounts for 11% of Egypt's population and 22% of its economy (PPP). The majority of the nation's commerce is generated there, or passes through the city. The great majority of publishing houses and media outlets and nearly all film studios are there, as are half of the nation's hospital beds and universities. This has fuelled rapid construction in the city, with one building in five being less than 15 years old.",
"title": "Economy"
},
{
"paragraph_id": 60,
"text": "This growth until recently surged well ahead of city services. Homes, roads, electricity, telephone and sewer services were all in short supply. Analysts trying to grasp the magnitude of the change coined terms like \"hyper-urbanization\".",
"title": "Economy"
},
{
"paragraph_id": 61,
"text": "Cairo, as well as neighbouring Giza, has been established as Egypt's main centre for medical treatment, and despite some exceptions, has the most advanced level of medical care in the country. Cairo's hospitals include the JCI-accredited As-Salaam International Hospital—Corniche El Nile, Maadi (Egypt's largest private hospital with 350 beds), Ain Shams University Hospital, Dar Al Fouad, Nile Badrawi Hospital, 57357 Hospital, as well as Qasr El Eyni Hospital.",
"title": "Infrastructure"
},
{
"paragraph_id": 62,
"text": "Greater Cairo has long been the hub of education and educational services for Egypt and the region.",
"title": "Infrastructure"
},
{
"paragraph_id": 63,
"text": "Today, Greater Cairo is the centre for many government offices governing the Egyptian educational system, has the largest number of educational schools, and higher education institutes among other cities and governorates of Egypt.",
"title": "Infrastructure"
},
{
"paragraph_id": 64,
"text": "Some of the International Schools found in Cairo:",
"title": "Infrastructure"
},
{
"paragraph_id": 65,
"text": "Universities in Greater Cairo:",
"title": "Infrastructure"
},
{
"paragraph_id": 66,
"text": "Cairo has an extensive road network, rail system, subway system and maritime services. Road transport is facilitated by personal vehicles, taxi cabs, privately owned public buses and microbuses. Cairo International Airport is the country's largest airport and one of the busiest airports in Africa.",
"title": "Infrastructure"
},
{
"paragraph_id": 67,
"text": "Cairo, specifically Ramses Station, is the centre of almost the entire Egyptian transportation network.",
"title": "Infrastructure"
},
{
"paragraph_id": 68,
"text": "The Cairo Transportation Authority (CTA) manages Cairo's public transit. The subway system, the Cairo Metro, is a fast and efficient way of getting around Cairo. The metro network covers Helwan and other suburbs. It can get very crowded during rush hour. Two train cars (the fourth and fifth ones) are reserved for women only, although women may ride in any car they want.",
"title": "Infrastructure"
},
{
"paragraph_id": 69,
"text": "Trams in Greater Cairo and Cairo trolleybus were used as modes of transportation, but were closed in the 1970s everywhere except Heliopolis and Helwan. These were shut down in 2014, after the Egyptian Revolution.",
"title": "Infrastructure"
},
{
"paragraph_id": 70,
"text": "In 2017, plans to construct two monorail systems were announced, one linking 6th of October to suburban Giza, a distance of 35 km (22 mi), and the other linking Nasr City to New Cairo, a distance of 52 km (32 mi).",
"title": "Infrastructure"
},
{
"paragraph_id": 71,
"text": "An extensive road network connects Cairo with other Egyptian cities and villages. There is a new Ring Road that surrounds the outskirts of the city, with exits that reach outer Cairo districts. There are flyovers and bridges, such as the 6th October Bridge that, when the traffic is not heavy, allow fast means of transportation from one side of the city to the other.",
"title": "Infrastructure"
},
{
"paragraph_id": 72,
"text": "Cairo traffic is known to be overwhelming and overcrowded. Traffic moves at a relatively fluid pace. Drivers tend to be aggressive, but are more courteous at junctions, taking turns going, with police aiding in traffic control of some congested areas.",
"title": "Infrastructure"
},
{
"paragraph_id": 73,
"text": "President Mubarak inaugurated the new Cairo Opera House of the Egyptian National Cultural Centres on 10 October 1988, 17 years after the Royal Opera House had been destroyed by fire. The National Cultural Centre was built with the help of JICA, the Japan International Co-operation Agency and stands as a prominent feature for the Japanese-Egyptian co-operation and the friendship between the two nations.",
"title": "Culture"
},
{
"paragraph_id": 74,
"text": "The Khedivial Opera House, or Royal Opera House, was the original opera house in Cairo. It was dedicated on 1 November 1869 and burned down on 28 October 1971. After the original opera house was destroyed, Cairo was without an opera house for nearly two decades until the opening of the new Cairo Opera House in 1988.",
"title": "Culture"
},
{
"paragraph_id": 75,
"text": "Cairo held its first international film festival 16 August 1976, when the first Cairo International Film Festival was launched by the Egyptian Association of Film Writers and Critics, headed by Kamal El-Mallakh. The Association ran the festival for seven years until 1983.",
"title": "Culture"
},
{
"paragraph_id": 76,
"text": "This achievement lead to the President of the Festival again contacting the FIAPF with the request that a competition should be included at the 1991 Festival. The request was granted.",
"title": "Culture"
},
{
"paragraph_id": 77,
"text": "In 1998, the Festival took place under the presidency of one of Egypt's leading actors, Hussein Fahmy, who was appointed by the Minister of Culture, Farouk Hosni, after the death of Saad El-Din Wahba. Four years later, the journalist and writer Cherif El-Shoubashy became president.",
"title": "Culture"
},
{
"paragraph_id": 78,
"text": "The Cairo Geniza is an accumulation of almost 200,000 Jewish manuscripts that were found in the genizah of the Ben Ezra synagogue (built 882) of Fustat, Egypt (now Old Cairo), the Basatin cemetery east of Old Cairo, and a number of old documents that were bought in Cairo in the later 19th century. These documents were written from about 870 to 1880 AD and have been archived in various American and European libraries. The Taylor-Schechter collection in the University of Cambridge runs to 140,000 manuscripts; a further 40,000 manuscripts are housed at the Jewish Theological Seminary of America.",
"title": "Culture"
},
{
"paragraph_id": 79,
"text": "The majority of Cairenes make food for themselves and make use of local produce markets. The restaurant scene includes Arab cuisine and Middle Eastern cuisine, including local staples such as koshary. The city's most exclusive restaurants are typically concentrated in Zamalek and around the luxury hotels lining the shore of the Nile near the Garden City district. Influence from modern western society is also evident, with American chains such as McDonald's, Arby's, Pizza Hut, Subway, and Kentucky Fried Chicken being easy to find in central areas.",
"title": "Culture"
},
{
"paragraph_id": 80,
"text": "Football is the most popular sport in Egypt, and Cairo has a number of sporting teams that compete in national and regional leagues, most notably Al Ahly and Zamalek SC, who are the CAF first and second African clubs of the 20th century. The annual match between Al Ahly and El Zamalek is one of the most watched sports events in Egypt as well as the African-Arab region. The teams form the major rivalry of Egyptian football and are the first and the second champions in Africa and the Arab world. They play their home games at Cairo International Stadium or Naser Stadium, which is the second largest stadium in Egypt, as well as the largest in Cairo and one of the largest stadiums in the world.",
"title": "Sports"
},
{
"paragraph_id": 81,
"text": "The Cairo International Stadium was built in 1960 and its multi-purpose sports complex that houses the main football stadium, an indoor stadium, several satellite fields that held several regional, continental, and global games, including the African Games, U17 Football World Championship and were one of the stadiums scheduled that hosted the 2006 Africa Cup of Nations which was played in January 2006. Egypt later won the competition and went on to win the next edition in Ghana (2008) making the Egyptian and Ghanaian national teams the only teams to win the African Nations Cup Back to back which resulted in Egypt winning the title for a record number of six times in the history of African Continental Competition. This was followed by a third consecutive win in Angola in 2010, making Egypt the only country with a record 3-consecutive and 7-total Continental Football Competition winner. This achievement also placed the Egyptian football team as the #9 best team in the world's FIFA rankings. As of 2021, Egypt's national team is ranked #46 in the world by FIFA.",
"title": "Sports"
},
{
"paragraph_id": 82,
"text": "Cairo failed at the applicant stage when bidding for the 2008 Summer Olympics, which was hosted in Beijing, China. However, Cairo did host the 2007 Pan Arab Games.",
"title": "Sports"
},
{
"paragraph_id": 83,
"text": "There are several other sports teams in the city that participate in several sports including Gezira Sporting Club, el Shams Club, el Seid Club, Heliopolis Sporting Club, and several smaller clubs, but the biggest clubs in Egypt (not in the area but in sports) are Al Ahly and Zamalek. They have the two biggest football teams in Egypt. There are new sports clubs in the area of New Cairo (one hour far from Cairo's downtown), these are Al Zohour sporting club, Wadi Degla sporting club and Platinum Club.",
"title": "Sports"
},
{
"paragraph_id": 84,
"text": "Most of the sports federations of the country are also located in the city suburbs, including the Egyptian Football Association. The headquarters of the Confederation of African Football (CAF) was previously located in Cairo, before relocating to its new headquarters in 6 October City, a small city away from Cairo's crowded districts.",
"title": "Sports"
},
{
"paragraph_id": 85,
"text": "In October 2008, the Egyptian Rugby Federation was officially formed and granted membership into the International Rugby Board.",
"title": "Sports"
},
{
"paragraph_id": 86,
"text": "Egypt is internationally known for the excellence of its squash players who excel in professional and junior divisions. Egypt has seven players in the top ten of the PSA men's world rankings, and three in the women's top ten. Mohamed El Shorbagy held the world number one position for more than a year before being overtaken by compatriot Karim Abdel Gawad, who is number two behind Gregory Gaultier of France. Ramy Ashour and Amr Shabana are regarded as two of the most talented squash players in history. Shabana won the World Open title four times and Ashour twice, although his recent form has been hampered by injury. Egypt's Nour El Sherbini has won the Women's World Championship twice and has been women's world number one for 16 consecutive months. On 30 April 2016, she became the youngest woman to win the Women's World Championship which was held in Malaysia. In April 2017 she retained her title by winning the Women's World Championship which was held in the Egyptian resort of El Gouna.",
"title": "Sports"
},
{
"paragraph_id": 87,
"text": "Cairo is the official end point of Cross Egypt Challenge where its route ends yearly in the most sacred place in Egypt, under the Great Pyramids of Giza with a huge trophy-giving ceremony.",
"title": "Sports"
},
{
"paragraph_id": 88,
"text": "Tahrir Square was founded during the mid 19th century with the establishment of modern downtown Cairo. It was first named Ismailia Square, after the 19th-century ruler Khedive Ismail, who commissioned the new downtown district's 'Paris on the Nile' design. After the Egyptian Revolution of 1919 the square became widely known as Tahrir (Liberation) Square, though it was not officially renamed as such until after the 1952 Revolution which eliminated the monarchy. Several notable buildings surround the square including, the American University in Cairo's downtown campus, the Mogamma governmental administrative Building, the headquarters of the Arab League, the Nile Ritz Carlton Hotel, and the Egyptian Museum. Being at the heart of Cairo, the square witnessed several major protests over the years. However, the most notable event in the square was being the focal point of the 2011 Egyptian Revolution against former president Hosni Mubarak. In 2020 the government completed the erection of a new monument in the center of the square featuring an ancient obelisk from the reign of Ramses II, originally unearthed at Tanis (San al-Hagar) in 2019, and four ram-headed sphinx statues moved from Karnak.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 89,
"text": "The Museum of Egyptian Antiquities, known commonly as the Egyptian Museum, is home to the most extensive collection of ancient Egyptian antiquities in the world. It has 136,000 items on display, with many more hundreds of thousands in its basement storerooms. Among the collections on display are the finds from the tomb of Tutankhamun.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 90,
"text": "Much of the collection of the Museum of Egyptian Antiquities, including the Tutankhamun collection, are slated to be moved to the new Grand Egyptian Museum, under construction in Giza and was due to open by the end of 2020.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 91,
"text": "The Cairo Tower is a free-standing tower with a revolving restaurant at the top. It provides a bird's eye view of Cairo to the restaurant patrons. It stands in the Zamalek district on Gezira Island in the Nile River, in the city centre. At 187 m (614 ft), it is 44 m (144 ft) higher than the Great Pyramid of Giza, which stands some 15 km (9 mi) to the southwest.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 92,
"text": "This area of Cairo is so-named as it contains the remains of the ancient Roman fortress of Babylon and also overlaps the original site of Fustat, the first Arab settlement in Egypt (7th century AD) and the predecessor of later Cairo. The area includes Coptic Cairo, which holds a high concentration of old Christian churches such as the Hanging Church, the Greek Orthodox Church of St. George, and other Christian or Coptic buildings, most of which are located in an enclave on the site of the ancient Roman fortress. It is also the location of the Coptic Museum, which showcases the history of Coptic art from Greco-Roman to Islamic times, and of the Ben Ezra Synagogue, the oldest and best-known synagogue in Cairo, where the important collection of Geniza documents were discovered in the 19th century.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 93,
"text": "To the north of this Coptic enclave is the Amr ibn al-'As Mosque, the first mosque in Egypt and the most important religious centre of what was formerly Fustat, founded in 642 AD right after the Arab conquest but rebuilt many times since. A part of the former city of Fustat has also been excavated to the east of the mosque and of the Coptic enclave, although the archeological site is threatened by encroaching construction and modern development. To the northwest of Babylon Fortress and the mosque is the Monastery of Saint Mercurius (or Dayr Abu Sayfayn), an important and historic Coptic religious complex consisting of the Church of Saint Mercurius, the Church of Saint Shenute, and the Church of the Virgin (also known as al-Damshiriya). Several other historic churches are also situated to the south of Babylon Fortress.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 94,
"text": "Cairo holds one of the greatest concentrations of historical monuments of Islamic architecture in the world. The areas around the old walled city and around the Citadel are characterized by hundreds of mosques, tombs, madrasas, mansions, caravanserais, and fortifications dating from the Islamic era and are often referred to as \"Islamic Cairo\", especially in English travel literature. It is also the location of several important religious shrines such as the al-Hussein Mosque (whose shrine is believed to hold the head of Husayn ibn Ali), the Mausoleum of Imam al-Shafi'i (founder of the Shafi'i madhhab, one of the primary schools of thought in Sunni Islamic jurisprudence), the Tomb of Sayyida Ruqayya, the Mosque of Sayyida Nafisa, and others.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 95,
"text": "The first mosque in Egypt was the Mosque of Amr ibn al-As in what was formerly Fustat, the first Arab-Muslim settlement in the area. However, the Mosque of Ibn Tulun is the oldest mosque that still retains its original form and is a rare example of Abbasid architecture from the classical period of Islamic civilization. It was built in 876–879 AD in a style inspired by the Abbasid capital of Samarra in Iraq. It is one of the largest mosques in Cairo and is often cited as one of the most beautiful. Another Abbasid construction, the Nilometer on Roda Island, is the oldest original structure in Cairo, built in 862 AD. It was designed to measure the level of the Nile, which was important for agricultural and administrative purposes.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 96,
"text": "The settlement that was formally named Cairo (Arabic: al-Qahira) was founded to the northeast of Fustat in 959 AD by the victorious Fatimid army. The Fatimids built it as a separate palatial city which contained their palaces and institutions of government. It was enclosed by a circuit of walls, which were rebuilt in stone in the late 11th century AD by the vizier Badr al-Gamali, parts of which survive today at Bab Zuwayla in the south and Bab al-Futuh and Bab al-Nasr in the north. Among the extant monuments from the Fatimid era are the large Mosque of al-Hakim, the Aqmar Mosque, Juyushi Mosque, Lulua Mosque, and the Mosque of Al-Salih Tala'i.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 97,
"text": "One of the most important and lasting institutions founded in the Fatimid period was the Mosque of al-Azhar, founded in 970 AD, which competes with the Qarawiyyin in Fes for the title of oldest university in the world. Today, al-Azhar University is the foremost Center of Islamic learning in the world and one of Egypt's largest universities with campuses across the country. The mosque itself retains significant Fatimid elements but has been added to and expanded in subsequent centuries, notably by the Mamluk sultans Qaytbay and al-Ghuri and by Abd al-Rahman Katkhuda in the 18th century.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 98,
"text": "The most prominent architectural heritage of medieval Cairo, however, dates from the Mamluk period, from 1250 to 1517 AD. The Mamluk sultans and elites were eager patrons of religious and scholarly life, commonly building religious or funerary complexes whose functions could include a mosque, madrasa, khanqah (for Sufis), a sabil (water dispensary), and a mausoleum for themselves and their families. Among the best-known examples of Mamluk monuments in Cairo are the huge Mosque-Madrasa of Sultan Hasan, the Mosque of Amir al-Maridani, the Mosque of Sultan al-Mu'ayyad (whose twin minarets were built above the gate of Bab Zuwayla), the Sultan Al-Ghuri complex, the funerary complex of Sultan Qaytbay in the Northern Cemetery, and the trio of monuments in the Bayn al-Qasrayn area comprising the complex of Sultan al-Mansur Qalawun, the Madrasa of al-Nasir Muhammad, and the Madrasa of Sultan Barquq. Some mosques include spolia (often columns or capitals) from earlier buildings built by the Romans, Byzantines, or Copts.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 99,
"text": "The Mamluks, and the later Ottomans, also built wikalas or caravanserais to house merchants and goods due to the important role of trade and commerce in Cairo's economy. Still intact today is the Wikala al-Ghuri, which today hosts regular performances by the Al-Tannoura Egyptian Heritage Dance Troupe. The Khan al-Khalili is a commercial hub which also integrated caravanserais (also known as khans).",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 100,
"text": "The Citadel is a fortified enclosure begun by Salah al-Din in 1176 AD on an outcrop of the Muqattam Hills as part of a large defensive system to protect both Cairo to the north and Fustat to the southwest. It was the centre of Egyptian government and residence of its rulers until 1874, when Khedive Isma'il moved to 'Abdin Palace. It is still occupied by the military today, but is now open as a tourist attraction comprising, notably, the National Military Museum, the 14th century Mosque of al-Nasir Muhammad, and the 19th century Mosque of Muhammad Ali which commands a dominant position on Cairo's skyline.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 101,
"text": "Khan el-Khalili is an ancient bazaar, or marketplace adjacent to the Al-Hussein Mosque. It dates back to 1385, when Amir Jarkas el-Khalili built a large caravanserai, or khan. (A caravanserai is a hotel for traders, and usually the focal point for any surrounding area.) This original caravanserai building was demolished by Sultan al-Ghuri, who rebuilt it as a new commercial complex in the early 16th century, forming the basis for the network of souqs existing today. Many medieval elements remain today, including the ornate Mamluk-style gateways. Today, the Khan el-Khalili is a major tourist attraction and popular stop for tour groups.",
"title": "Cityscape and landmarks"
},
{
"paragraph_id": 102,
"text": "In the present day, Cairo is heavily urbanized and most Cairenes live in apartment buildings. Because of the influx of people into the city, lone standing houses are rare, and apartment buildings accommodate for the limited space and abundance of people. Single detached houses are usually owned by the wealthy. Formal education is also seen as important, with twelve years of standard formal education. Cairenes can take a standardized test similar to the SAT to be accepted to an institution of higher learning, but most children do not finish school and opt to pick up a trade to enter the work force. Egypt still struggles with poverty, with almost half the population living on $2 or less a day.",
"title": "Society"
},
{
"paragraph_id": 103,
"text": "The civil rights movement for women in Cairo – and by extent, Egypt – has been a struggle for years. Women are reported to face constant discrimination, sexual harassment, and abuse throughout Cairo. A 2013 UN study found that over 99% of Egyptian women reported experiencing sexual harassment at some point in their lives. The problem has persisted in spite of new national laws since 2014 defining and criminalizing sexual harassment. The situation is so severe that in 2017, Cairo was named by one poll as the most dangerous megacity for women in the world. In 2020, the social media account \"Assault Police\" began to name and shame perpetrators of violence against women, in an effort to dissuade potential offenders. The account was founded by student Nadeen Ashraf, who is credited for instigating an iteration of the #MeToo movement in Egypt.",
"title": "Society"
},
{
"paragraph_id": 104,
"text": "The air pollution in Cairo is a matter of serious concern. Greater Cairo's volatile aromatic hydrocarbon levels are higher than many other similar cities. Air quality measurements in Cairo have also been recording dangerous levels of lead, carbon dioxide, sulphur dioxide, and suspended particulate matter concentrations due to decades of unregulated vehicle emissions, urban industrial operations, and chaff and trash burning. There are over 4,500,000 cars on the streets of Cairo, 60% of which are over 10 years old, and therefore lack modern emission cutting features. Cairo has a very poor dispersion factor because of its lack of rain and its layout of tall buildings and narrow streets, which create a bowl effect.",
"title": "Pollution"
},
{
"paragraph_id": 105,
"text": "In recent years, a black cloud (as Egyptians refer to it) of smog has appeared over Cairo every autumn due to temperature inversion. Smog causes serious respiratory diseases and eye irritations for the city's citizens. Tourists who are not familiar with such high levels of pollution must take extra care.",
"title": "Pollution"
},
{
"paragraph_id": 106,
"text": "Cairo also has many unregistered lead and copper smelters which heavily pollute the city. The results of this has been a permanent haze over the city with particulate matter in the air reaching over three times normal levels. It is estimated that 10,000 to 25,000 people a year in Cairo die due to air pollution-related diseases. Lead has been shown to cause harm to the central nervous system and neurotoxicity particularly in children. In 1995, the first environmental acts were introduced and the situation has seen some improvement with 36 air monitoring stations and emissions tests on cars. Twenty thousand buses have also been commissioned to the city to improve congestion levels, which are very high.",
"title": "Pollution"
},
{
"paragraph_id": 107,
"text": "The city also suffers from a high level of land pollution. Cairo produces 10,000 tons of waste material each day, 4,000 tons of which is not collected or managed. This is a huge health hazard, and the Egyptian Government is looking for ways to combat this. The Cairo Cleaning and Beautification Agency was founded to collect and recycle the waste; they work with the Zabbaleen community that has been collecting and recycling Cairo's waste since the turn of the 20th century and live in an area known locally as Manshiyat naser. Both are working together to pick up as much waste as possible within the city limits, though it remains a pressing problem.",
"title": "Pollution"
},
{
"paragraph_id": 108,
"text": "Water pollution is also a serious problem in the city as the sewer system tends to fail and overflow. On occasion, sewage has escaped onto the streets to create a health hazard. This problem is hoped to be solved by a new sewer system funded by the European Union, which could cope with the demand of the city. The dangerously high levels of mercury in the city's water system has global health officials concerned over related health risks.",
"title": "Pollution"
},
{
"paragraph_id": 109,
"text": "The Headquarters of the Arab League is located in Tahrir Square, near the downtown business district of Cairo.",
"title": "International relations"
},
{
"paragraph_id": 110,
"text": "Cairo is twinned with:",
"title": "International relations"
}
] | Cairo is the capital of Egypt and the city-state Cairo Governorate, and is the country's largest city, home to 10 million people. It is also part of the largest urban agglomeration in Africa, the Arab world and the Middle East: The Greater Cairo metropolitan area is the 12th-largest in the world by population with a population of over 22.1 million. Cairo is associated with ancient Egypt, as the Giza pyramid complex and the ancient cities of Memphis and Heliopolis are located in its geographical area. Located near the Nile Delta, the city first developed as Fustat following the Muslim conquest of Egypt in 641 next to an existing ancient Roman fortress, Babylon. Cairo was founded by the Fatimid dynasty in 969. It later superseded Fustat as the main urban centre during the Ayyubid and Mamluk periods. Cairo has long been a centre of the region's political and cultural life, and is titled "the city of a thousand minarets" for its preponderance of Islamic architecture. Cairo's historic center was awarded World Heritage Site status in 1979. Cairo is considered a World City with a "Beta +" classification according to GaWC. Cairo has the oldest and largest film and music industry in the Arab world, as well as Egypt's oldest institution of higher learning, Al-Azhar University. Many international media, businesses, and organizations have regional headquarters in the city; the Arab League has had its headquarters in Cairo for most of its existence. With a population of over 10 million spread over 453 km2 (175 sq mi), Cairo is by far the largest city in Egypt. An additional 9.5 million inhabitants live close to the city. Cairo, like many other megacities, suffers from high levels of pollution and traffic. The Cairo Metro, opened in 1987, is the oldest metro system in Africa, and ranks amongst the fifteen busiest in the world, with over 1 billion annual passenger rides. The economy of Cairo was ranked first in the Middle East in 2005, and 43rd globally on Foreign Policy's 2010 Global Cities Index. | 2001-09-07T22:49:44Z | 2023-12-31T19:03:08Z | [
"Template:Cairo weatherbox",
"Template:Notelist",
"Template:Refbegin",
"Template:Citation needed",
"Template:Citation",
"Template:Cite book",
"Template:Dead link",
"Template:Use dmy dates",
"Template:Lang-cop",
"Template:Lang-arz",
"Template:See also",
"Template:More citations needed",
"Template:Cite web",
"Template:For timeline",
"Template:Circa",
"Template:Historical populations",
"Template:Navboxes",
"Template:Unreferenced section",
"Template:ISBN",
"Template:Harvnb",
"Template:Main",
"Template:Multiple image",
"Template:Div col",
"Template:Lang-ar",
"Template:IPA-arz",
"Template:Better source needed",
"Template:Further",
"Template:Reflist",
"Template:Cite magazine",
"Template:Cite journal",
"Template:Wide image",
"Template:Cite thesis",
"Template:Cbignore",
"Template:URL",
"Template:Osmrelation-inline",
"Template:Infobox settlement",
"Template:IPA-all",
"Template:Cn",
"Template:IPAc-en",
"Template:Sister project links",
"Template:Authority control",
"Template:Respell",
"Template:Div col end",
"Template:Webarchive",
"Template:Short description",
"Template:Sfn",
"Template:Lang",
"Template:Cvt",
"Template:Efn",
"Template:In lang",
"Template:Refend",
"Template:Transliteration",
"Template:Coptic",
"Template:Clarify",
"Template:Cite news",
"Template:About",
"Template:'s",
"Template:Cite encyclopedia"
] | https://en.wikipedia.org/wiki/Cairo |
6,295 | Chaos theory | Chaos theory is an interdisciplinary area of scientific study and branch of mathematics focused on underlying patterns and deterministic laws of dynamical systems that are highly sensitive to initial conditions, and were once thought to have completely random states of disorder and irregularities. Chaos theory states that within the apparent randomness of chaotic complex systems, there are underlying patterns, interconnection, constant feedback loops, repetition, self-similarity, fractals, and self-organization. The butterfly effect, an underlying principle of chaos, describes how a small change in one state of a deterministic nonlinear system can result in large differences in a later state (meaning that there is sensitive dependence on initial conditions). A metaphor for this behavior is that a butterfly flapping its wings in Texas can cause a tornado in Brazil.
Small differences in initial conditions, such as those due to errors in measurements or due to rounding errors in numerical computation, can yield widely diverging outcomes for such dynamical systems, rendering long-term prediction of their behavior impossible in general. This can happen even though these systems are deterministic, meaning that their future behavior follows a unique evolution and is fully determined by their initial conditions, with no random elements involved. In other words, the deterministic nature of these systems does not make them predictable. This behavior is known as deterministic chaos, or simply chaos. The theory was summarized by Edward Lorenz as:
Chaos: When the present determines the future, but the approximate present does not approximately determine the future.
Chaotic behavior exists in many natural systems, including fluid flow, heartbeat irregularities, weather, and climate. It also occurs spontaneously in some systems with artificial components, such as road traffic. This behavior can be studied through the analysis of a chaotic mathematical model, or through analytical techniques such as recurrence plots and Poincaré maps. Chaos theory has applications in a variety of disciplines, including meteorology, anthropology, sociology, environmental science, computer science, engineering, economics, ecology, and pandemic crisis management. The theory formed the basis for such fields of study as complex dynamical systems, edge of chaos theory, and self-assembly processes.
Chaos theory concerns deterministic systems whose behavior can, in principle, be predicted. Chaotic systems are predictable for a while and then 'appear' to become random. The amount of time for which the behavior of a chaotic system can be effectively predicted depends on three things: how much uncertainty can be tolerated in the forecast, how accurately its current state can be measured, and a time scale depending on the dynamics of the system, called the Lyapunov time. Some examples of Lyapunov times are: chaotic electrical circuits, about 1 millisecond; weather systems, a few days (unproven); the inner solar system, 4 to 5 million years. In chaotic systems, the uncertainty in a forecast increases exponentially with elapsed time. Hence, mathematically, doubling the forecast time more than squares the proportional uncertainty in the forecast. This means, in practice, a meaningful prediction cannot be made over an interval of more than two or three times the Lyapunov time. When meaningful predictions cannot be made, the system appears random.
Chaos theory is a method of qualitative and quantitative analysis to investigate the behavior of dynamic systems that cannot be explained and predicted by single data relationships, but must be explained and predicted by whole, continuous data relationships.
In common usage, "chaos" means "a state of disorder". However, in chaos theory, the term is defined more precisely. Although no universally accepted mathematical definition of chaos exists, a commonly used definition, originally formulated by Robert L. Devaney, says that to classify a dynamical system as chaotic, it must have these properties:
In some cases, the last two properties above have been shown to actually imply sensitivity to initial conditions. In the discrete-time case, this is true for all continuous maps on metric spaces. In these cases, while it is often the most practically significant property, "sensitivity to initial conditions" need not be stated in the definition.
If attention is restricted to intervals, the second property implies the other two. An alternative and a generally weaker definition of chaos uses only the first two properties in the above list.
Sensitivity to initial conditions means that each point in a chaotic system is arbitrarily closely approximated by other points that have significantly different future paths or trajectories. Thus, an arbitrarily small change or perturbation of the current trajectory may lead to significantly different future behavior.
Sensitivity to initial conditions is popularly known as the "butterfly effect", so-called because of the title of a paper given by Edward Lorenz in 1972 to the American Association for the Advancement of Science in Washington, D.C., entitled Predictability: Does the Flap of a Butterfly's Wings in Brazil set off a Tornado in Texas?. The flapping wing represents a small change in the initial condition of the system, which causes a chain of events that prevents the predictability of large-scale phenomena. Had the butterfly not flapped its wings, the trajectory of the overall system could have been vastly different.
As suggested in Lorenz's book entitled The Essence of Chaos, published in 1993, "sensitive dependence can serve as an acceptable definition of chaos". In the same book, Lorenz defined the butterfly effect as: "The phenomenon that a small alteration in the state of a dynamical system will cause subsequent states to differ greatly from the states that would have followed without the alteration." The above definition is consistent with the sensitive dependence of solutions on initial conditions (SDIC). An idealized skiing model was developed to illustrate the sensitivity of time-varying paths to initial positions. A predictability horizon can be determined before the onset of SDIC (i.e., prior to significant separations of initial nearby trajectories).
A consequence of sensitivity to initial conditions is that if we start with a limited amount of information about the system (as is usually the case in practice), then beyond a certain time, the system would no longer be predictable. This is most prevalent in the case of weather, which is generally predictable only about a week ahead. This does not mean that one cannot assert anything about events far in the future—only that some restrictions on the system are present. For example, we know that the temperature of the surface of the earth will not naturally reach 100 °C (212 °F) or fall below −130 °C (−202 °F) on earth (during the current geologic era), but we cannot predict exactly which day will have the hottest temperature of the year.
In more mathematical terms, the Lyapunov exponent measures the sensitivity to initial conditions, in the form of rate of exponential divergence from the perturbed initial conditions. More specifically, given two starting trajectories in the phase space that are infinitesimally close, with initial separation δ Z 0 {\displaystyle \delta \mathbf {Z} _{0}} , the two trajectories end up diverging at a rate given by
where t {\displaystyle t} is the time and λ {\displaystyle \lambda } is the Lyapunov exponent. The rate of separation depends on the orientation of the initial separation vector, so a whole spectrum of Lyapunov exponents can exist. The number of Lyapunov exponents is equal to the number of dimensions of the phase space, though it is common to just refer to the largest one. For example, the maximal Lyapunov exponent (MLE) is most often used, because it determines the overall predictability of the system. A positive MLE is usually taken as an indication that the system is chaotic.
In addition to the above property, other properties related to sensitivity of initial conditions also exist. These include, for example, measure-theoretical mixing (as discussed in ergodic theory) and properties of a K-system.
A chaotic system may have sequences of values for the evolving variable that exactly repeat themselves, giving periodic behavior starting from any point in that sequence. However, such periodic sequences are repelling rather than attracting, meaning that if the evolving variable is outside the sequence, however close, it will not enter the sequence and in fact, will diverge from it. Thus for almost all initial conditions, the variable evolves chaotically with non-periodic behavior.
Topological mixing (or the weaker condition of topological transitivity) means that the system evolves over time so that any given region or open set of its phase space eventually overlaps with any other given region. This mathematical concept of "mixing" corresponds to the standard intuition, and the mixing of colored dyes or fluids is an example of a chaotic system.
Topological mixing is often omitted from popular accounts of chaos, which equate chaos with only sensitivity to initial conditions. However, sensitive dependence on initial conditions alone does not give chaos. For example, consider the simple dynamical system produced by repeatedly doubling an initial value. This system has sensitive dependence on initial conditions everywhere, since any pair of nearby points eventually becomes widely separated. However, this example has no topological mixing, and therefore has no chaos. Indeed, it has extremely simple behavior: all points except 0 tend to positive or negative infinity.
A map f : X → X {\displaystyle f:X\to X} is said to be topologically transitive if for any pair of non-empty open sets U , V ⊂ X {\displaystyle U,V\subset X} , there exists k > 0 {\displaystyle k>0} such that f k ( U ) ∩ V ≠ ∅ {\displaystyle f^{k}(U)\cap V\neq \emptyset } . Topological transitivity is a weaker version of topological mixing. Intuitively, if a map is topologically transitive then given a point x and a region V, there exists a point y near x whose orbit passes through V. This implies that it is impossible to decompose the system into two open sets.
An important related theorem is the Birkhoff Transitivity Theorem. It is easy to see that the existence of a dense orbit implies topological transitivity. The Birkhoff Transitivity Theorem states that if X is a second countable, complete metric space, then topological transitivity implies the existence of a dense set of points in X that have dense orbits.
For a chaotic system to have dense periodic orbits means that every point in the space is approached arbitrarily closely by periodic orbits. The one-dimensional logistic map defined by x → 4 x (1 – x) is one of the simplest systems with density of periodic orbits. For example, 5 − 5 8 {\displaystyle {\tfrac {5-{\sqrt {5}}}{8}}} → 5 + 5 8 {\displaystyle {\tfrac {5+{\sqrt {5}}}{8}}} → 5 − 5 8 {\displaystyle {\tfrac {5-{\sqrt {5}}}{8}}} (or approximately 0.3454915 → 0.9045085 → 0.3454915) is an (unstable) orbit of period 2, and similar orbits exist for periods 4, 8, 16, etc. (indeed, for all the periods specified by Sharkovskii's theorem).
Sharkovskii's theorem is the basis of the Li and Yorke (1975) proof that any continuous one-dimensional system that exhibits a regular cycle of period three will also display regular cycles of every other length, as well as completely chaotic orbits.
Some dynamical systems, like the one-dimensional logistic map defined by x → 4 x (1 – x), are chaotic everywhere, but in many cases chaotic behavior is found only in a subset of phase space. The cases of most interest arise when the chaotic behavior takes place on an attractor, since then a large set of initial conditions leads to orbits that converge to this chaotic region.
An easy way to visualize a chaotic attractor is to start with a point in the basin of attraction of the attractor, and then simply plot its subsequent orbit. Because of the topological transitivity condition, this is likely to produce a picture of the entire final attractor, and indeed both orbits shown in the figure on the right give a picture of the general shape of the Lorenz attractor. This attractor results from a simple three-dimensional model of the Lorenz weather system. The Lorenz attractor is perhaps one of the best-known chaotic system diagrams, probably because it is not only one of the first, but it is also one of the most complex, and as such gives rise to a very interesting pattern that, with a little imagination, looks like the wings of a butterfly.
Unlike fixed-point attractors and limit cycles, the attractors that arise from chaotic systems, known as strange attractors, have great detail and complexity. Strange attractors occur in both continuous dynamical systems (such as the Lorenz system) and in some discrete systems (such as the Hénon map). Other discrete dynamical systems have a repelling structure called a Julia set, which forms at the boundary between basins of attraction of fixed points. Julia sets can be thought of as strange repellers. Both strange attractors and Julia sets typically have a fractal structure, and the fractal dimension can be calculated for them.
In contrast to single type chaotic solutions, recent studies using Lorenz models have emphasized the importance of considering various types of solutions. For example, coexisting chaotic and non-chaotic may appear within the same model (e.g., the double pendulum system) using the same modeling configurations but different initial conditions. The findings of attractor coexistence, obtained from classical and generalized Lorenz models, suggested a revised view that "the entirety of weather possesses a dual nature of chaos and order with distinct predictability", in contrast to the conventional view of "weather is chaotic".
Discrete chaotic systems, such as the logistic map, can exhibit strange attractors whatever their dimensionality. Universality of one-dimensional maps with parabolic maxima and Feigenbaum constants δ = 4.669201... {\displaystyle \delta =4.669201...} , α = 2.502907... {\displaystyle \alpha =2.502907...} is well visible with Tahn map proposed as a toy model for discrete laser dynamics: x → G x ( 1 − t a n h ( x ) ) {\displaystyle x\rightarrow Gx(1-\mathrm {tanh} (x))} , where x {\displaystyle x} stands for electric field amplitude, G {\displaystyle G} is laser gain as bifurcation parameter. The gradual increase of G {\displaystyle G} at interval [ 0 , ∞ ) {\displaystyle [0,\infty )} changes dynamics from regular to chaotic one with qualitatively the same bifurcation diagram as those for logistic map.
In contrast, for continuous dynamical systems, the Poincaré–Bendixson theorem shows that a strange attractor can only arise in three or more dimensions. Finite-dimensional linear systems are never chaotic; for a dynamical system to display chaotic behavior, it must be either nonlinear or infinite-dimensional.
The Poincaré–Bendixson theorem states that a two-dimensional differential equation has very regular behavior. The Lorenz attractor discussed below is generated by a system of three differential equations such as:
where x {\displaystyle x} , y {\displaystyle y} , and z {\displaystyle z} make up the system state, t {\displaystyle t} is time, and σ {\displaystyle \sigma } , ρ {\displaystyle \rho } , β {\displaystyle \beta } are the system parameters. Five of the terms on the right hand side are linear, while two are quadratic; a total of seven terms. Another well-known chaotic attractor is generated by the Rössler equations, which have only one nonlinear term out of seven. Sprott found a three-dimensional system with just five terms, that had only one nonlinear term, which exhibits chaos for certain parameter values. Zhang and Heidel showed that, at least for dissipative and conservative quadratic systems, three-dimensional quadratic systems with only three or four terms on the right-hand side cannot exhibit chaotic behavior. The reason is, simply put, that solutions to such systems are asymptotic to a two-dimensional surface and therefore solutions are well behaved.
While the Poincaré–Bendixson theorem shows that a continuous dynamical system on the Euclidean plane cannot be chaotic, two-dimensional continuous systems with non-Euclidean geometry can exhibit chaotic behavior. Perhaps surprisingly, chaos may occur also in linear systems, provided they are infinite dimensional. A theory of linear chaos is being developed in a branch of mathematical analysis known as functional analysis.
The above elegant set of three ordinary differential equations has been referred to as the three-dimensional Lorenz model. Since 1963, higher-dimensional Lorenz models have been developed in numerous studies for examining the impact of an increased degree of nonlinearity, as well as its collective effect with heating and dissipations, on solution stability.
The straightforward generalization of coupled discrete maps is based upon convolution integral which mediates interaction between spatially distributed maps: ψ n + 1 ( r → , t ) = ∫ K ( r → − r → , , t ) f [ ψ n ( r → , , t ) ] d r → , {\displaystyle \psi _{n+1}({\vec {r}},t)=\int K({\vec {r}}-{\vec {r}}^{,},t)f[\psi _{n}({\vec {r}}^{,},t)]d{\vec {r}}^{,}} ,
where kernel K ( r → − r → , , t ) {\displaystyle K({\vec {r}}-{\vec {r}}^{,},t)} is propagator derived as Green function of a relevant physical system, f [ ψ n ( r → , t ) ] {\displaystyle f[\psi _{n}({\vec {r}},t)]} might be logistic map alike ψ → G ψ [ 1 − tanh ( ψ ) ] {\displaystyle \psi \rightarrow G\psi [1-\tanh(\psi )]} or complex map. For examples of complex maps the Julia set f [ ψ ] = ψ 2 {\displaystyle f[\psi ]=\psi ^{2}} or Ikeda map ψ n + 1 = A + B ψ n e i ( | ψ n | 2 + C ) {\displaystyle \psi _{n+1}=A+B\psi _{n}e^{i(|\psi _{n}|^{2}+C)}} may serve. When wave propagation problems at distance L = c t {\displaystyle L=ct} with wavelength λ = 2 π / k {\displaystyle \lambda =2\pi /k} are considered the kernel K {\displaystyle K} may have a form of Green function for Schrödinger equation:.
K ( r → − r → , , L ) = i k exp [ i k L ] 2 π L exp [ i k | r → − r → , | 2 2 L ] {\displaystyle K({\vec {r}}-{\vec {r}}^{,},L)={\frac {ik\exp[ikL]}{2\pi L}}\exp[{\frac {ik|{\vec {r}}-{\vec {r}}^{,}|^{2}}{2L}}]} .
In physics, jerk is the third derivative of position, with respect to time. As such, differential equations of the form
are sometimes called jerk equations. It has been shown that a jerk equation, which is equivalent to a system of three first order, ordinary, non-linear differential equations, is in a certain sense the minimal setting for solutions showing chaotic behavior. This motivates mathematical interest in jerk systems. Systems involving a fourth or higher derivative are called accordingly hyperjerk systems.
A jerk system's behavior is described by a jerk equation, and for certain jerk equations, simple electronic circuits can model solutions. These circuits are known as jerk circuits.
One of the most interesting properties of jerk circuits is the possibility of chaotic behavior. In fact, certain well-known chaotic systems, such as the Lorenz attractor and the Rössler map, are conventionally described as a system of three first-order differential equations that can combine into a single (although rather complicated) jerk equation. Another example of a jerk equation with nonlinearity in the magnitude of x {\displaystyle x} is:
Here, A is an adjustable parameter. This equation has a chaotic solution for A=3/5 and can be implemented with the following jerk circuit; the required nonlinearity is brought about by the two diodes:
In the above circuit, all resistors are of equal value, except R A = R / A = 5 R / 3 {\displaystyle R_{A}=R/A=5R/3} , and all capacitors are of equal size. The dominant frequency is 1 / 2 π R C {\displaystyle 1/2\pi RC} . The output of op amp 0 will correspond to the x variable, the output of 1 corresponds to the first derivative of x and the output of 2 corresponds to the second derivative.
Similar circuits only require one diode or no diodes at all.
See also the well-known Chua's circuit, one basis for chaotic true random number generators. The ease of construction of the circuit has made it a ubiquitous real-world example of a chaotic system.
Under the right conditions, chaos spontaneously evolves into a lockstep pattern. In the Kuramoto model, four conditions suffice to produce synchronization in a chaotic system. Examples include the coupled oscillation of Christiaan Huygens' pendulums, fireflies, neurons, the London Millennium Bridge resonance, and large arrays of Josephson junctions.
James Clerk Maxwell first emphasized the "butterfly effect", and is seen as being one of the earliest to discuss chaos theory, with work in the 1860s and 1870s. An early proponent of chaos theory was Henri Poincaré. In the 1880s, while studying the three-body problem, he found that there can be orbits that are nonperiodic, and yet not forever increasing nor approaching a fixed point. In 1898, Jacques Hadamard published an influential study of the chaotic motion of a free particle gliding frictionlessly on a surface of constant negative curvature, called "Hadamard's billiards". Hadamard was able to show that all trajectories are unstable, in that all particle trajectories diverge exponentially from one another, with a positive Lyapunov exponent.
Chaos theory began in the field of ergodic theory. Later studies, also on the topic of nonlinear differential equations, were carried out by George David Birkhoff, Andrey Nikolaevich Kolmogorov, Mary Lucy Cartwright and John Edensor Littlewood, and Stephen Smale. Except for Smale, these studies were all directly inspired by physics: the three-body problem in the case of Birkhoff, turbulence and astronomical problems in the case of Kolmogorov, and radio engineering in the case of Cartwright and Littlewood. Although chaotic planetary motion had not been observed, experimentalists had encountered turbulence in fluid motion and nonperiodic oscillation in radio circuits without the benefit of a theory to explain what they were seeing.
Despite initial insights in the first half of the twentieth century, chaos theory became formalized as such only after mid-century, when it first became evident to some scientists that linear theory, the prevailing system theory at that time, simply could not explain the observed behavior of certain experiments like that of the logistic map. What had been attributed to measure imprecision and simple "noise" was considered by chaos theorists as a full component of the studied systems. In 1959 Boris Valerianovich Chirikov proposed a criterion for the emergence of classical chaos in Hamiltonian systems (Chirikov criterion). He applied this criterion to explain some experimental results on plasma confinement in open mirror traps. This is regarded as the very first physical theory of chaos, which succeeded in explaining a concrete experiment. And Boris Chirikov himself is considered as a pioneer in classical and quantum chaos.
The main catalyst for the development of chaos theory was the electronic computer. Much of the mathematics of chaos theory involves the repeated iteration of simple mathematical formulas, which would be impractical to do by hand. Electronic computers made these repeated calculations practical, while figures and images made it possible to visualize these systems. As a graduate student in Chihiro Hayashi's laboratory at Kyoto University, Yoshisuke Ueda was experimenting with analog computers and noticed, on November 27, 1961, what he called "randomly transitional phenomena". Yet his advisor did not agree with his conclusions at the time, and did not allow him to report his findings until 1970.
Edward Lorenz was an early pioneer of the theory. His interest in chaos came about accidentally through his work on weather prediction in 1961. Lorenz and his collaborator Ellen Fetter and Margaret Hamilton were using a simple digital computer, a Royal McBee LGP-30, to run weather simulations. They wanted to see a sequence of data again, and to save time they started the simulation in the middle of its course. They did this by entering a printout of the data that corresponded to conditions in the middle of the original simulation. To their surprise, the weather the machine began to predict was completely different from the previous calculation. They tracked this down to the computer printout. The computer worked with 6-digit precision, but the printout rounded variables off to a 3-digit number, so a value like 0.506127 printed as 0.506. This difference is tiny, and the consensus at the time would have been that it should have no practical effect. However, Lorenz discovered that small changes in initial conditions produced large changes in long-term outcome. Lorenz's discovery, which gave its name to Lorenz attractors, showed that even detailed atmospheric modeling cannot, in general, make precise long-term weather predictions.
In 1963, Benoit Mandelbrot, studying information theory, discovered that noise in many phenomena (including stock prices and telephone circuits) was patterned like a Cantor set, a set of points with infinite roughness and detail Mandelbrot described both the "Noah effect" (in which sudden discontinuous changes can occur) and the "Joseph effect" (in which persistence of a value can occur for a while, yet suddenly change afterwards). In 1967, he published "How long is the coast of Britain? Statistical self-similarity and fractional dimension", showing that a coastline's length varies with the scale of the measuring instrument, resembles itself at all scales, and is infinite in length for an infinitesimally small measuring device. Arguing that a ball of twine appears as a point when viewed from far away (0-dimensional), a ball when viewed from fairly near (3-dimensional), or a curved strand (1-dimensional), he argued that the dimensions of an object are relative to the observer and may be fractional. An object whose irregularity is constant over different scales ("self-similarity") is a fractal (examples include the Menger sponge, the Sierpiński gasket, and the Koch curve or snowflake, which is infinitely long yet encloses a finite space and has a fractal dimension of circa 1.2619). In 1982, Mandelbrot published The Fractal Geometry of Nature, which became a classic of chaos theory.
In December 1977, the New York Academy of Sciences organized the first symposium on chaos, attended by David Ruelle, Robert May, James A. Yorke (coiner of the term "chaos" as used in mathematics), Robert Shaw, and the meteorologist Edward Lorenz. The following year Pierre Coullet and Charles Tresser published "Itérations d'endomorphismes et groupe de renormalisation", and Mitchell Feigenbaum's article "Quantitative Universality for a Class of Nonlinear Transformations" finally appeared in a journal, after 3 years of referee rejections. Thus Feigenbaum (1975) and Coullet & Tresser (1978) discovered the universality in chaos, permitting the application of chaos theory to many different phenomena.
In 1979, Albert J. Libchaber, during a symposium organized in Aspen by Pierre Hohenberg, presented his experimental observation of the bifurcation cascade that leads to chaos and turbulence in Rayleigh–Bénard convection systems. He was awarded the Wolf Prize in Physics in 1986 along with Mitchell J. Feigenbaum for their inspiring achievements.
In 1986, the New York Academy of Sciences co-organized with the National Institute of Mental Health and the Office of Naval Research the first important conference on chaos in biology and medicine. There, Bernardo Huberman presented a mathematical model of the eye tracking dysfunction among people with schizophrenia. This led to a renewal of physiology in the 1980s through the application of chaos theory, for example, in the study of pathological cardiac cycles.
In 1987, Per Bak, Chao Tang and Kurt Wiesenfeld published a paper in Physical Review Letters describing for the first time self-organized criticality (SOC), considered one of the mechanisms by which complexity arises in nature.
Alongside largely lab-based approaches such as the Bak–Tang–Wiesenfeld sandpile, many other investigations have focused on large-scale natural or social systems that are known (or suspected) to display scale-invariant behavior. Although these approaches were not always welcomed (at least initially) by specialists in the subjects examined, SOC has nevertheless become established as a strong candidate for explaining a number of natural phenomena, including earthquakes, (which, long before SOC was discovered, were known as a source of scale-invariant behavior such as the Gutenberg–Richter law describing the statistical distribution of earthquake sizes, and the Omori law describing the frequency of aftershocks), solar flares, fluctuations in economic systems such as financial markets (references to SOC are common in econophysics), landscape formation, forest fires, landslides, epidemics, and biological evolution (where SOC has been invoked, for example, as the dynamical mechanism behind the theory of "punctuated equilibria" put forward by Niles Eldredge and Stephen Jay Gould). Given the implications of a scale-free distribution of event sizes, some researchers have suggested that another phenomenon that should be considered an example of SOC is the occurrence of wars. These investigations of SOC have included both attempts at modelling (either developing new models or adapting existing ones to the specifics of a given natural system), and extensive data analysis to determine the existence and/or characteristics of natural scaling laws.
In the same year, James Gleick published Chaos: Making a New Science, which became a best-seller and introduced the general principles of chaos theory as well as its history to the broad public. Initially the domain of a few, isolated individuals, chaos theory progressively emerged as a transdisciplinary and institutional discipline, mainly under the name of nonlinear systems analysis. Alluding to Thomas Kuhn's concept of a paradigm shift exposed in The Structure of Scientific Revolutions (1962), many "chaologists" (as some described themselves) claimed that this new theory was an example of such a shift, a thesis upheld by Gleick.
The availability of cheaper, more powerful computers broadens the applicability of chaos theory. Currently, chaos theory remains an active area of research, involving many different disciplines such as mathematics, topology, physics, social systems, population modeling, biology, meteorology, astrophysics, information theory, computational neuroscience, pandemic crisis management, etc.
Throughout his career, Professor Lorenz authored a total of 61 research papers, out of which 58 were solely authored by him. Commencing with the 1960 conference in Japan, Lorenz embarked on a journey of developing diverse models aimed at uncovering the SDIC and chaotic features. A recent review of Lorenz's model progression spanning from 1960 to 2008 revealed his adeptness at employing varied physical systems to illustrate chaotic phenomena. These systems encompassed Quasi-geostrophic systems, the Conservative Vorticity Equation, the Rayleigh-Bénard Convection Equations, and the Shallow Water Equations. Moreover, Lorenz can be credited with the early application of the logistic map to explore chaotic solutions, a milestone he achieved ahead of his colleagues (e.g. Lorenz 1964 ).
In 1972, Lorenz coined the term "butterfly effect" as a metaphor to discuss whether a small perturbation could eventually create a tornado with a three-dimensional, organized, and coherent structure. While connected to the original butterfly effect based on sensitive dependence on initial conditions, its metaphorical variant carries distinct nuances. To commemorate this milestone, a reprint book containing invited papers that deepen our understanding of both butterfly effects was officially published to celebrate the 50th anniversary of the metaphorical butterfly effect.
The sensitive dependence on initial conditions (i.e., butterfly effect) has been illustrated using the following folklore:
For want of a nail, the shoe was lost.
For want of a shoe, the horse was lost.
For want of a horse, the rider was lost.
For want of a rider, the battle was lost.
For want of a battle, the kingdom was lost.
And all for the want of a horseshoe nail.
Based on the above, many people mistakenly believe that the impact of a tiny initial perturbation monotonically increases with time and that any tiny perturbation can eventually produce a large impact on numerical integrations. However, in 2008, Lorenz stated that he did not feel that this verse described true chaos but that it better illustrated the simpler phenomenon of instability and that the verse implicitly suggests that subsequent small events will not reverse the outcome (Lorenz, 2008 ). Based on the analysis, the verse only indicates divergence, not boundedness. Boundedness is important for the finite size of a butterfly pattern. In a recent study, the characteristic of the aforementioned verse was recently denoted as "finite-time sensitive dependence".
Although chaos theory was born from observing weather patterns, it has become applicable to a variety of other situations. Some areas benefiting from chaos theory today are geology, mathematics, biology, computer science, economics, engineering, finance, meteorology, philosophy, anthropology, physics, politics, population dynamics, and robotics. A few categories are listed below with examples, but this is by no means a comprehensive list as new applications are appearing.
Chaos theory has been used for many years in cryptography. In the past few decades, chaos and nonlinear dynamics have been used in the design of hundreds of cryptographic primitives. These algorithms include image encryption algorithms, hash functions, secure pseudo-random number generators, stream ciphers, watermarking, and steganography. The majority of these algorithms are based on uni-modal chaotic maps and a big portion of these algorithms use the control parameters and the initial condition of the chaotic maps as their keys. From a wider perspective, without loss of generality, the similarities between the chaotic maps and the cryptographic systems is the main motivation for the design of chaos based cryptographic algorithms. One type of encryption, secret key or symmetric key, relies on diffusion and confusion, which is modeled well by chaos theory. Another type of computing, DNA computing, when paired with chaos theory, offers a way to encrypt images and other information. Many of the DNA-Chaos cryptographic algorithms are proven to be either not secure, or the technique applied is suggested to be not efficient.
Robotics is another area that has recently benefited from chaos theory. Instead of robots acting in a trial-and-error type of refinement to interact with their environment, chaos theory has been used to build a predictive model. Chaotic dynamics have been exhibited by passive walking biped robots.
For over a hundred years, biologists have been keeping track of populations of different species with population models. Most models are continuous, but recently scientists have been able to implement chaotic models in certain populations. For example, a study on models of Canadian lynx showed there was chaotic behavior in the population growth. Chaos can also be found in ecological systems, such as hydrology. While a chaotic model for hydrology has its shortcomings, there is still much to learn from looking at the data through the lens of chaos theory. Another biological application is found in cardiotocography. Fetal surveillance is a delicate balance of obtaining accurate information while being as noninvasive as possible. Better models of warning signs of fetal hypoxia can be obtained through chaotic modeling.
As Perry points out, modeling of chaotic time series in ecology is helped by constraint. There is always potential difficulty in distinguishing real chaos from chaos that is only in the model. Hence both constraint in the model and or duplicate time series data for comparison will be helpful in constraining the model to something close to the reality, for example Perry & Wall 1984. Gene-for-gene co-evolution sometimes shows chaotic dynamics in allele frequencies. Adding variables exaggerates this: Chaos is more common in models incorporating additional variables to reflect additional facets of real populations. Robert M. May himself did some of these foundational crop co-evolution studies, and this in turn helped shape the entire field. Even for a steady environment, merely combining one crop and one pathogen may result in quasi-periodic- or chaotic- oscillations in pathogen population.
It is possible that economic models can also be improved through an application of chaos theory, but predicting the health of an economic system and what factors influence it most is an extremely complex task. Economic and financial systems are fundamentally different from those in the classical natural sciences since the former are inherently stochastic in nature, as they result from the interactions of people, and thus pure deterministic models are unlikely to provide accurate representations of the data. The empirical literature that tests for chaos in economics and finance presents very mixed results, in part due to confusion between specific tests for chaos and more general tests for non-linear relationships.
Chaos could be found in economics by the means of recurrence quantification analysis. In fact, Orlando et al. by the means of the so-called recurrence quantification correlation index were able detect hidden changes in time series. Then, the same technique was employed to detect transitions from laminar (regular) to turbulent (chaotic) phases as well as differences between macroeconomic variables and highlight hidden features of economic dynamics. Finally, chaos theory could help in modeling how an economy operates as well as in embedding shocks due to external events such as COVID-19.
In chemistry, predicting gas solubility is essential to manufacturing polymers, but models using particle swarm optimization (PSO) tend to converge to the wrong points. An improved version of PSO has been created by introducing chaos, which keeps the simulations from getting stuck. In celestial mechanics, especially when observing asteroids, applying chaos theory leads to better predictions about when these objects will approach Earth and other planets. Four of the five moons of Pluto rotate chaotically. In quantum physics and electrical engineering, the study of large arrays of Josephson junctions benefitted greatly from chaos theory. Closer to home, coal mines have always been dangerous places where frequent natural gas leaks cause many deaths. Until recently, there was no reliable way to predict when they would occur. But these gas leaks have chaotic tendencies that, when properly modeled, can be predicted fairly accurately.
Chaos theory can be applied outside of the natural sciences, but historically nearly all such studies have suffered from lack of reproducibility; poor external validity; and/or inattention to cross-validation, resulting in poor predictive accuracy (if out-of-sample prediction has even been attempted). Glass and Mandell and Selz have found that no EEG study has as yet indicated the presence of strange attractors or other signs of chaotic behavior.
Researchers have continued to apply chaos theory to psychology. For example, in modeling group behavior in which heterogeneous members may behave as if sharing to different degrees what in Wilfred Bion's theory is a basic assumption, researchers have found that the group dynamic is the result of the individual dynamics of the members: each individual reproduces the group dynamics in a different scale, and the chaotic behavior of the group is reflected in each member.
Redington and Reidbord (1992) attempted to demonstrate that the human heart could display chaotic traits. They monitored the changes in between-heartbeat intervals for a single psychotherapy patient as she moved through periods of varying emotional intensity during a therapy session. Results were admittedly inconclusive. Not only were there ambiguities in the various plots the authors produced to purportedly show evidence of chaotic dynamics (spectral analysis, phase trajectory, and autocorrelation plots), but also when they attempted to compute a Lyapunov exponent as more definitive confirmation of chaotic behavior, the authors found they could not reliably do so.
In their 1995 paper, Metcalf and Allen maintained that they uncovered in animal behavior a pattern of period doubling leading to chaos. The authors examined a well-known response called schedule-induced polydipsia, by which an animal deprived of food for certain lengths of time will drink unusual amounts of water when the food is at last presented. The control parameter (r) operating here was the length of the interval between feedings, once resumed. The authors were careful to test a large number of animals and to include many replications, and they designed their experiment so as to rule out the likelihood that changes in response patterns were caused by different starting places for r.
Time series and first delay plots provide the best support for the claims made, showing a fairly clear march from periodicity to irregularity as the feeding times were increased. The various phase trajectory plots and spectral analyses, on the other hand, do not match up well enough with the other graphs or with the overall theory to lead inexorably to a chaotic diagnosis. For example, the phase trajectories do not show a definite progression towards greater and greater complexity (and away from periodicity); the process seems quite muddied. Also, where Metcalf and Allen saw periods of two and six in their spectral plots, there is room for alternative interpretations. All of this ambiguity necessitate some serpentine, post-hoc explanation to show that results fit a chaotic model.
By adapting a model of career counseling to include a chaotic interpretation of the relationship between employees and the job market, Amundson and Bright found that better suggestions can be made to people struggling with career decisions. Modern organizations are increasingly seen as open complex adaptive systems with fundamental natural nonlinear structures, subject to internal and external forces that may contribute chaos. For instance, team building and group development is increasingly being researched as an inherently unpredictable system, as the uncertainty of different individuals meeting for the first time makes the trajectory of the team unknowable.
Some say the chaos metaphor—used in verbal theories—grounded on mathematical models and psychological aspects of human behavior provides helpful insights to describing the complexity of small work groups, that go beyond the metaphor itself.
Traffic forecasting may benefit from applications of chaos theory. Better predictions of when a congestion will occur would allow measures to be taken to disperse it before it would have occurred. Combining chaos theory principles with a few other methods has led to a more accurate short-term prediction model (see the plot of the BML traffic model at right).
Chaos theory has been applied to environmental water cycle data (also hydrological data), such as rainfall and streamflow. These studies have yielded controversial results, because the methods for detecting a chaotic signature are often relatively subjective. Early studies tended to "succeed" in finding chaos, whereas subsequent studies and meta-analyses called those studies into question and provided explanations for why these datasets are not likely to have low-dimension chaotic dynamics.
In art (predominately art theory) a possible postpostmodern era has been outlined with emphasis on multiple narratives and the notion that every fictional angle is a possibility. In part this is therefor of a bisociate (trissociative) discourse and can be explained within emphasis on an institutional interchange of subjectivistic agents.
Examples of chaotic systems
Other related topics
People | [
{
"paragraph_id": 0,
"text": "Chaos theory is an interdisciplinary area of scientific study and branch of mathematics focused on underlying patterns and deterministic laws of dynamical systems that are highly sensitive to initial conditions, and were once thought to have completely random states of disorder and irregularities. Chaos theory states that within the apparent randomness of chaotic complex systems, there are underlying patterns, interconnection, constant feedback loops, repetition, self-similarity, fractals, and self-organization. The butterfly effect, an underlying principle of chaos, describes how a small change in one state of a deterministic nonlinear system can result in large differences in a later state (meaning that there is sensitive dependence on initial conditions). A metaphor for this behavior is that a butterfly flapping its wings in Texas can cause a tornado in Brazil.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Small differences in initial conditions, such as those due to errors in measurements or due to rounding errors in numerical computation, can yield widely diverging outcomes for such dynamical systems, rendering long-term prediction of their behavior impossible in general. This can happen even though these systems are deterministic, meaning that their future behavior follows a unique evolution and is fully determined by their initial conditions, with no random elements involved. In other words, the deterministic nature of these systems does not make them predictable. This behavior is known as deterministic chaos, or simply chaos. The theory was summarized by Edward Lorenz as:",
"title": ""
},
{
"paragraph_id": 2,
"text": "Chaos: When the present determines the future, but the approximate present does not approximately determine the future.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Chaotic behavior exists in many natural systems, including fluid flow, heartbeat irregularities, weather, and climate. It also occurs spontaneously in some systems with artificial components, such as road traffic. This behavior can be studied through the analysis of a chaotic mathematical model, or through analytical techniques such as recurrence plots and Poincaré maps. Chaos theory has applications in a variety of disciplines, including meteorology, anthropology, sociology, environmental science, computer science, engineering, economics, ecology, and pandemic crisis management. The theory formed the basis for such fields of study as complex dynamical systems, edge of chaos theory, and self-assembly processes.",
"title": ""
},
{
"paragraph_id": 4,
"text": "Chaos theory concerns deterministic systems whose behavior can, in principle, be predicted. Chaotic systems are predictable for a while and then 'appear' to become random. The amount of time for which the behavior of a chaotic system can be effectively predicted depends on three things: how much uncertainty can be tolerated in the forecast, how accurately its current state can be measured, and a time scale depending on the dynamics of the system, called the Lyapunov time. Some examples of Lyapunov times are: chaotic electrical circuits, about 1 millisecond; weather systems, a few days (unproven); the inner solar system, 4 to 5 million years. In chaotic systems, the uncertainty in a forecast increases exponentially with elapsed time. Hence, mathematically, doubling the forecast time more than squares the proportional uncertainty in the forecast. This means, in practice, a meaningful prediction cannot be made over an interval of more than two or three times the Lyapunov time. When meaningful predictions cannot be made, the system appears random.",
"title": "Introduction"
},
{
"paragraph_id": 5,
"text": "Chaos theory is a method of qualitative and quantitative analysis to investigate the behavior of dynamic systems that cannot be explained and predicted by single data relationships, but must be explained and predicted by whole, continuous data relationships.",
"title": "Introduction"
},
{
"paragraph_id": 6,
"text": "In common usage, \"chaos\" means \"a state of disorder\". However, in chaos theory, the term is defined more precisely. Although no universally accepted mathematical definition of chaos exists, a commonly used definition, originally formulated by Robert L. Devaney, says that to classify a dynamical system as chaotic, it must have these properties:",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 7,
"text": "In some cases, the last two properties above have been shown to actually imply sensitivity to initial conditions. In the discrete-time case, this is true for all continuous maps on metric spaces. In these cases, while it is often the most practically significant property, \"sensitivity to initial conditions\" need not be stated in the definition.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 8,
"text": "If attention is restricted to intervals, the second property implies the other two. An alternative and a generally weaker definition of chaos uses only the first two properties in the above list.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 9,
"text": "Sensitivity to initial conditions means that each point in a chaotic system is arbitrarily closely approximated by other points that have significantly different future paths or trajectories. Thus, an arbitrarily small change or perturbation of the current trajectory may lead to significantly different future behavior.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 10,
"text": "Sensitivity to initial conditions is popularly known as the \"butterfly effect\", so-called because of the title of a paper given by Edward Lorenz in 1972 to the American Association for the Advancement of Science in Washington, D.C., entitled Predictability: Does the Flap of a Butterfly's Wings in Brazil set off a Tornado in Texas?. The flapping wing represents a small change in the initial condition of the system, which causes a chain of events that prevents the predictability of large-scale phenomena. Had the butterfly not flapped its wings, the trajectory of the overall system could have been vastly different.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 11,
"text": "As suggested in Lorenz's book entitled The Essence of Chaos, published in 1993, \"sensitive dependence can serve as an acceptable definition of chaos\". In the same book, Lorenz defined the butterfly effect as: \"The phenomenon that a small alteration in the state of a dynamical system will cause subsequent states to differ greatly from the states that would have followed without the alteration.\" The above definition is consistent with the sensitive dependence of solutions on initial conditions (SDIC). An idealized skiing model was developed to illustrate the sensitivity of time-varying paths to initial positions. A predictability horizon can be determined before the onset of SDIC (i.e., prior to significant separations of initial nearby trajectories).",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 12,
"text": "A consequence of sensitivity to initial conditions is that if we start with a limited amount of information about the system (as is usually the case in practice), then beyond a certain time, the system would no longer be predictable. This is most prevalent in the case of weather, which is generally predictable only about a week ahead. This does not mean that one cannot assert anything about events far in the future—only that some restrictions on the system are present. For example, we know that the temperature of the surface of the earth will not naturally reach 100 °C (212 °F) or fall below −130 °C (−202 °F) on earth (during the current geologic era), but we cannot predict exactly which day will have the hottest temperature of the year.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 13,
"text": "In more mathematical terms, the Lyapunov exponent measures the sensitivity to initial conditions, in the form of rate of exponential divergence from the perturbed initial conditions. More specifically, given two starting trajectories in the phase space that are infinitesimally close, with initial separation δ Z 0 {\\displaystyle \\delta \\mathbf {Z} _{0}} , the two trajectories end up diverging at a rate given by",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 14,
"text": "where t {\\displaystyle t} is the time and λ {\\displaystyle \\lambda } is the Lyapunov exponent. The rate of separation depends on the orientation of the initial separation vector, so a whole spectrum of Lyapunov exponents can exist. The number of Lyapunov exponents is equal to the number of dimensions of the phase space, though it is common to just refer to the largest one. For example, the maximal Lyapunov exponent (MLE) is most often used, because it determines the overall predictability of the system. A positive MLE is usually taken as an indication that the system is chaotic.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 15,
"text": "In addition to the above property, other properties related to sensitivity of initial conditions also exist. These include, for example, measure-theoretical mixing (as discussed in ergodic theory) and properties of a K-system.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 16,
"text": "A chaotic system may have sequences of values for the evolving variable that exactly repeat themselves, giving periodic behavior starting from any point in that sequence. However, such periodic sequences are repelling rather than attracting, meaning that if the evolving variable is outside the sequence, however close, it will not enter the sequence and in fact, will diverge from it. Thus for almost all initial conditions, the variable evolves chaotically with non-periodic behavior.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 17,
"text": "Topological mixing (or the weaker condition of topological transitivity) means that the system evolves over time so that any given region or open set of its phase space eventually overlaps with any other given region. This mathematical concept of \"mixing\" corresponds to the standard intuition, and the mixing of colored dyes or fluids is an example of a chaotic system.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 18,
"text": "Topological mixing is often omitted from popular accounts of chaos, which equate chaos with only sensitivity to initial conditions. However, sensitive dependence on initial conditions alone does not give chaos. For example, consider the simple dynamical system produced by repeatedly doubling an initial value. This system has sensitive dependence on initial conditions everywhere, since any pair of nearby points eventually becomes widely separated. However, this example has no topological mixing, and therefore has no chaos. Indeed, it has extremely simple behavior: all points except 0 tend to positive or negative infinity.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 19,
"text": "A map f : X → X {\\displaystyle f:X\\to X} is said to be topologically transitive if for any pair of non-empty open sets U , V ⊂ X {\\displaystyle U,V\\subset X} , there exists k > 0 {\\displaystyle k>0} such that f k ( U ) ∩ V ≠ ∅ {\\displaystyle f^{k}(U)\\cap V\\neq \\emptyset } . Topological transitivity is a weaker version of topological mixing. Intuitively, if a map is topologically transitive then given a point x and a region V, there exists a point y near x whose orbit passes through V. This implies that it is impossible to decompose the system into two open sets.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 20,
"text": "An important related theorem is the Birkhoff Transitivity Theorem. It is easy to see that the existence of a dense orbit implies topological transitivity. The Birkhoff Transitivity Theorem states that if X is a second countable, complete metric space, then topological transitivity implies the existence of a dense set of points in X that have dense orbits.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 21,
"text": "For a chaotic system to have dense periodic orbits means that every point in the space is approached arbitrarily closely by periodic orbits. The one-dimensional logistic map defined by x → 4 x (1 – x) is one of the simplest systems with density of periodic orbits. For example, 5 − 5 8 {\\displaystyle {\\tfrac {5-{\\sqrt {5}}}{8}}} → 5 + 5 8 {\\displaystyle {\\tfrac {5+{\\sqrt {5}}}{8}}} → 5 − 5 8 {\\displaystyle {\\tfrac {5-{\\sqrt {5}}}{8}}} (or approximately 0.3454915 → 0.9045085 → 0.3454915) is an (unstable) orbit of period 2, and similar orbits exist for periods 4, 8, 16, etc. (indeed, for all the periods specified by Sharkovskii's theorem).",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 22,
"text": "Sharkovskii's theorem is the basis of the Li and Yorke (1975) proof that any continuous one-dimensional system that exhibits a regular cycle of period three will also display regular cycles of every other length, as well as completely chaotic orbits.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 23,
"text": "Some dynamical systems, like the one-dimensional logistic map defined by x → 4 x (1 – x), are chaotic everywhere, but in many cases chaotic behavior is found only in a subset of phase space. The cases of most interest arise when the chaotic behavior takes place on an attractor, since then a large set of initial conditions leads to orbits that converge to this chaotic region.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 24,
"text": "An easy way to visualize a chaotic attractor is to start with a point in the basin of attraction of the attractor, and then simply plot its subsequent orbit. Because of the topological transitivity condition, this is likely to produce a picture of the entire final attractor, and indeed both orbits shown in the figure on the right give a picture of the general shape of the Lorenz attractor. This attractor results from a simple three-dimensional model of the Lorenz weather system. The Lorenz attractor is perhaps one of the best-known chaotic system diagrams, probably because it is not only one of the first, but it is also one of the most complex, and as such gives rise to a very interesting pattern that, with a little imagination, looks like the wings of a butterfly.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 25,
"text": "Unlike fixed-point attractors and limit cycles, the attractors that arise from chaotic systems, known as strange attractors, have great detail and complexity. Strange attractors occur in both continuous dynamical systems (such as the Lorenz system) and in some discrete systems (such as the Hénon map). Other discrete dynamical systems have a repelling structure called a Julia set, which forms at the boundary between basins of attraction of fixed points. Julia sets can be thought of as strange repellers. Both strange attractors and Julia sets typically have a fractal structure, and the fractal dimension can be calculated for them.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 26,
"text": "In contrast to single type chaotic solutions, recent studies using Lorenz models have emphasized the importance of considering various types of solutions. For example, coexisting chaotic and non-chaotic may appear within the same model (e.g., the double pendulum system) using the same modeling configurations but different initial conditions. The findings of attractor coexistence, obtained from classical and generalized Lorenz models, suggested a revised view that \"the entirety of weather possesses a dual nature of chaos and order with distinct predictability\", in contrast to the conventional view of \"weather is chaotic\".",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 27,
"text": "Discrete chaotic systems, such as the logistic map, can exhibit strange attractors whatever their dimensionality. Universality of one-dimensional maps with parabolic maxima and Feigenbaum constants δ = 4.669201... {\\displaystyle \\delta =4.669201...} , α = 2.502907... {\\displaystyle \\alpha =2.502907...} is well visible with Tahn map proposed as a toy model for discrete laser dynamics: x → G x ( 1 − t a n h ( x ) ) {\\displaystyle x\\rightarrow Gx(1-\\mathrm {tanh} (x))} , where x {\\displaystyle x} stands for electric field amplitude, G {\\displaystyle G} is laser gain as bifurcation parameter. The gradual increase of G {\\displaystyle G} at interval [ 0 , ∞ ) {\\displaystyle [0,\\infty )} changes dynamics from regular to chaotic one with qualitatively the same bifurcation diagram as those for logistic map.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 28,
"text": "In contrast, for continuous dynamical systems, the Poincaré–Bendixson theorem shows that a strange attractor can only arise in three or more dimensions. Finite-dimensional linear systems are never chaotic; for a dynamical system to display chaotic behavior, it must be either nonlinear or infinite-dimensional.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 29,
"text": "The Poincaré–Bendixson theorem states that a two-dimensional differential equation has very regular behavior. The Lorenz attractor discussed below is generated by a system of three differential equations such as:",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 30,
"text": "where x {\\displaystyle x} , y {\\displaystyle y} , and z {\\displaystyle z} make up the system state, t {\\displaystyle t} is time, and σ {\\displaystyle \\sigma } , ρ {\\displaystyle \\rho } , β {\\displaystyle \\beta } are the system parameters. Five of the terms on the right hand side are linear, while two are quadratic; a total of seven terms. Another well-known chaotic attractor is generated by the Rössler equations, which have only one nonlinear term out of seven. Sprott found a three-dimensional system with just five terms, that had only one nonlinear term, which exhibits chaos for certain parameter values. Zhang and Heidel showed that, at least for dissipative and conservative quadratic systems, three-dimensional quadratic systems with only three or four terms on the right-hand side cannot exhibit chaotic behavior. The reason is, simply put, that solutions to such systems are asymptotic to a two-dimensional surface and therefore solutions are well behaved.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 31,
"text": "While the Poincaré–Bendixson theorem shows that a continuous dynamical system on the Euclidean plane cannot be chaotic, two-dimensional continuous systems with non-Euclidean geometry can exhibit chaotic behavior. Perhaps surprisingly, chaos may occur also in linear systems, provided they are infinite dimensional. A theory of linear chaos is being developed in a branch of mathematical analysis known as functional analysis.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 32,
"text": "The above elegant set of three ordinary differential equations has been referred to as the three-dimensional Lorenz model. Since 1963, higher-dimensional Lorenz models have been developed in numerous studies for examining the impact of an increased degree of nonlinearity, as well as its collective effect with heating and dissipations, on solution stability.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 33,
"text": "The straightforward generalization of coupled discrete maps is based upon convolution integral which mediates interaction between spatially distributed maps: ψ n + 1 ( r → , t ) = ∫ K ( r → − r → , , t ) f [ ψ n ( r → , , t ) ] d r → , {\\displaystyle \\psi _{n+1}({\\vec {r}},t)=\\int K({\\vec {r}}-{\\vec {r}}^{,},t)f[\\psi _{n}({\\vec {r}}^{,},t)]d{\\vec {r}}^{,}} ,",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 34,
"text": "where kernel K ( r → − r → , , t ) {\\displaystyle K({\\vec {r}}-{\\vec {r}}^{,},t)} is propagator derived as Green function of a relevant physical system, f [ ψ n ( r → , t ) ] {\\displaystyle f[\\psi _{n}({\\vec {r}},t)]} might be logistic map alike ψ → G ψ [ 1 − tanh ( ψ ) ] {\\displaystyle \\psi \\rightarrow G\\psi [1-\\tanh(\\psi )]} or complex map. For examples of complex maps the Julia set f [ ψ ] = ψ 2 {\\displaystyle f[\\psi ]=\\psi ^{2}} or Ikeda map ψ n + 1 = A + B ψ n e i ( | ψ n | 2 + C ) {\\displaystyle \\psi _{n+1}=A+B\\psi _{n}e^{i(|\\psi _{n}|^{2}+C)}} may serve. When wave propagation problems at distance L = c t {\\displaystyle L=ct} with wavelength λ = 2 π / k {\\displaystyle \\lambda =2\\pi /k} are considered the kernel K {\\displaystyle K} may have a form of Green function for Schrödinger equation:.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 35,
"text": "K ( r → − r → , , L ) = i k exp [ i k L ] 2 π L exp [ i k | r → − r → , | 2 2 L ] {\\displaystyle K({\\vec {r}}-{\\vec {r}}^{,},L)={\\frac {ik\\exp[ikL]}{2\\pi L}}\\exp[{\\frac {ik|{\\vec {r}}-{\\vec {r}}^{,}|^{2}}{2L}}]} .",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 36,
"text": "In physics, jerk is the third derivative of position, with respect to time. As such, differential equations of the form",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 37,
"text": "are sometimes called jerk equations. It has been shown that a jerk equation, which is equivalent to a system of three first order, ordinary, non-linear differential equations, is in a certain sense the minimal setting for solutions showing chaotic behavior. This motivates mathematical interest in jerk systems. Systems involving a fourth or higher derivative are called accordingly hyperjerk systems.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 38,
"text": "A jerk system's behavior is described by a jerk equation, and for certain jerk equations, simple electronic circuits can model solutions. These circuits are known as jerk circuits.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 39,
"text": "One of the most interesting properties of jerk circuits is the possibility of chaotic behavior. In fact, certain well-known chaotic systems, such as the Lorenz attractor and the Rössler map, are conventionally described as a system of three first-order differential equations that can combine into a single (although rather complicated) jerk equation. Another example of a jerk equation with nonlinearity in the magnitude of x {\\displaystyle x} is:",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 40,
"text": "Here, A is an adjustable parameter. This equation has a chaotic solution for A=3/5 and can be implemented with the following jerk circuit; the required nonlinearity is brought about by the two diodes:",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 41,
"text": "In the above circuit, all resistors are of equal value, except R A = R / A = 5 R / 3 {\\displaystyle R_{A}=R/A=5R/3} , and all capacitors are of equal size. The dominant frequency is 1 / 2 π R C {\\displaystyle 1/2\\pi RC} . The output of op amp 0 will correspond to the x variable, the output of 1 corresponds to the first derivative of x and the output of 2 corresponds to the second derivative.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 42,
"text": "Similar circuits only require one diode or no diodes at all.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 43,
"text": "See also the well-known Chua's circuit, one basis for chaotic true random number generators. The ease of construction of the circuit has made it a ubiquitous real-world example of a chaotic system.",
"title": "Chaotic dynamics"
},
{
"paragraph_id": 44,
"text": "Under the right conditions, chaos spontaneously evolves into a lockstep pattern. In the Kuramoto model, four conditions suffice to produce synchronization in a chaotic system. Examples include the coupled oscillation of Christiaan Huygens' pendulums, fireflies, neurons, the London Millennium Bridge resonance, and large arrays of Josephson junctions.",
"title": "Spontaneous order"
},
{
"paragraph_id": 45,
"text": "James Clerk Maxwell first emphasized the \"butterfly effect\", and is seen as being one of the earliest to discuss chaos theory, with work in the 1860s and 1870s. An early proponent of chaos theory was Henri Poincaré. In the 1880s, while studying the three-body problem, he found that there can be orbits that are nonperiodic, and yet not forever increasing nor approaching a fixed point. In 1898, Jacques Hadamard published an influential study of the chaotic motion of a free particle gliding frictionlessly on a surface of constant negative curvature, called \"Hadamard's billiards\". Hadamard was able to show that all trajectories are unstable, in that all particle trajectories diverge exponentially from one another, with a positive Lyapunov exponent.",
"title": "History"
},
{
"paragraph_id": 46,
"text": "Chaos theory began in the field of ergodic theory. Later studies, also on the topic of nonlinear differential equations, were carried out by George David Birkhoff, Andrey Nikolaevich Kolmogorov, Mary Lucy Cartwright and John Edensor Littlewood, and Stephen Smale. Except for Smale, these studies were all directly inspired by physics: the three-body problem in the case of Birkhoff, turbulence and astronomical problems in the case of Kolmogorov, and radio engineering in the case of Cartwright and Littlewood. Although chaotic planetary motion had not been observed, experimentalists had encountered turbulence in fluid motion and nonperiodic oscillation in radio circuits without the benefit of a theory to explain what they were seeing.",
"title": "History"
},
{
"paragraph_id": 47,
"text": "Despite initial insights in the first half of the twentieth century, chaos theory became formalized as such only after mid-century, when it first became evident to some scientists that linear theory, the prevailing system theory at that time, simply could not explain the observed behavior of certain experiments like that of the logistic map. What had been attributed to measure imprecision and simple \"noise\" was considered by chaos theorists as a full component of the studied systems. In 1959 Boris Valerianovich Chirikov proposed a criterion for the emergence of classical chaos in Hamiltonian systems (Chirikov criterion). He applied this criterion to explain some experimental results on plasma confinement in open mirror traps. This is regarded as the very first physical theory of chaos, which succeeded in explaining a concrete experiment. And Boris Chirikov himself is considered as a pioneer in classical and quantum chaos.",
"title": "History"
},
{
"paragraph_id": 48,
"text": "The main catalyst for the development of chaos theory was the electronic computer. Much of the mathematics of chaos theory involves the repeated iteration of simple mathematical formulas, which would be impractical to do by hand. Electronic computers made these repeated calculations practical, while figures and images made it possible to visualize these systems. As a graduate student in Chihiro Hayashi's laboratory at Kyoto University, Yoshisuke Ueda was experimenting with analog computers and noticed, on November 27, 1961, what he called \"randomly transitional phenomena\". Yet his advisor did not agree with his conclusions at the time, and did not allow him to report his findings until 1970.",
"title": "History"
},
{
"paragraph_id": 49,
"text": "Edward Lorenz was an early pioneer of the theory. His interest in chaos came about accidentally through his work on weather prediction in 1961. Lorenz and his collaborator Ellen Fetter and Margaret Hamilton were using a simple digital computer, a Royal McBee LGP-30, to run weather simulations. They wanted to see a sequence of data again, and to save time they started the simulation in the middle of its course. They did this by entering a printout of the data that corresponded to conditions in the middle of the original simulation. To their surprise, the weather the machine began to predict was completely different from the previous calculation. They tracked this down to the computer printout. The computer worked with 6-digit precision, but the printout rounded variables off to a 3-digit number, so a value like 0.506127 printed as 0.506. This difference is tiny, and the consensus at the time would have been that it should have no practical effect. However, Lorenz discovered that small changes in initial conditions produced large changes in long-term outcome. Lorenz's discovery, which gave its name to Lorenz attractors, showed that even detailed atmospheric modeling cannot, in general, make precise long-term weather predictions.",
"title": "History"
},
{
"paragraph_id": 50,
"text": "In 1963, Benoit Mandelbrot, studying information theory, discovered that noise in many phenomena (including stock prices and telephone circuits) was patterned like a Cantor set, a set of points with infinite roughness and detail Mandelbrot described both the \"Noah effect\" (in which sudden discontinuous changes can occur) and the \"Joseph effect\" (in which persistence of a value can occur for a while, yet suddenly change afterwards). In 1967, he published \"How long is the coast of Britain? Statistical self-similarity and fractional dimension\", showing that a coastline's length varies with the scale of the measuring instrument, resembles itself at all scales, and is infinite in length for an infinitesimally small measuring device. Arguing that a ball of twine appears as a point when viewed from far away (0-dimensional), a ball when viewed from fairly near (3-dimensional), or a curved strand (1-dimensional), he argued that the dimensions of an object are relative to the observer and may be fractional. An object whose irregularity is constant over different scales (\"self-similarity\") is a fractal (examples include the Menger sponge, the Sierpiński gasket, and the Koch curve or snowflake, which is infinitely long yet encloses a finite space and has a fractal dimension of circa 1.2619). In 1982, Mandelbrot published The Fractal Geometry of Nature, which became a classic of chaos theory.",
"title": "History"
},
{
"paragraph_id": 51,
"text": "In December 1977, the New York Academy of Sciences organized the first symposium on chaos, attended by David Ruelle, Robert May, James A. Yorke (coiner of the term \"chaos\" as used in mathematics), Robert Shaw, and the meteorologist Edward Lorenz. The following year Pierre Coullet and Charles Tresser published \"Itérations d'endomorphismes et groupe de renormalisation\", and Mitchell Feigenbaum's article \"Quantitative Universality for a Class of Nonlinear Transformations\" finally appeared in a journal, after 3 years of referee rejections. Thus Feigenbaum (1975) and Coullet & Tresser (1978) discovered the universality in chaos, permitting the application of chaos theory to many different phenomena.",
"title": "History"
},
{
"paragraph_id": 52,
"text": "In 1979, Albert J. Libchaber, during a symposium organized in Aspen by Pierre Hohenberg, presented his experimental observation of the bifurcation cascade that leads to chaos and turbulence in Rayleigh–Bénard convection systems. He was awarded the Wolf Prize in Physics in 1986 along with Mitchell J. Feigenbaum for their inspiring achievements.",
"title": "History"
},
{
"paragraph_id": 53,
"text": "In 1986, the New York Academy of Sciences co-organized with the National Institute of Mental Health and the Office of Naval Research the first important conference on chaos in biology and medicine. There, Bernardo Huberman presented a mathematical model of the eye tracking dysfunction among people with schizophrenia. This led to a renewal of physiology in the 1980s through the application of chaos theory, for example, in the study of pathological cardiac cycles.",
"title": "History"
},
{
"paragraph_id": 54,
"text": "In 1987, Per Bak, Chao Tang and Kurt Wiesenfeld published a paper in Physical Review Letters describing for the first time self-organized criticality (SOC), considered one of the mechanisms by which complexity arises in nature.",
"title": "History"
},
{
"paragraph_id": 55,
"text": "Alongside largely lab-based approaches such as the Bak–Tang–Wiesenfeld sandpile, many other investigations have focused on large-scale natural or social systems that are known (or suspected) to display scale-invariant behavior. Although these approaches were not always welcomed (at least initially) by specialists in the subjects examined, SOC has nevertheless become established as a strong candidate for explaining a number of natural phenomena, including earthquakes, (which, long before SOC was discovered, were known as a source of scale-invariant behavior such as the Gutenberg–Richter law describing the statistical distribution of earthquake sizes, and the Omori law describing the frequency of aftershocks), solar flares, fluctuations in economic systems such as financial markets (references to SOC are common in econophysics), landscape formation, forest fires, landslides, epidemics, and biological evolution (where SOC has been invoked, for example, as the dynamical mechanism behind the theory of \"punctuated equilibria\" put forward by Niles Eldredge and Stephen Jay Gould). Given the implications of a scale-free distribution of event sizes, some researchers have suggested that another phenomenon that should be considered an example of SOC is the occurrence of wars. These investigations of SOC have included both attempts at modelling (either developing new models or adapting existing ones to the specifics of a given natural system), and extensive data analysis to determine the existence and/or characteristics of natural scaling laws.",
"title": "History"
},
{
"paragraph_id": 56,
"text": "In the same year, James Gleick published Chaos: Making a New Science, which became a best-seller and introduced the general principles of chaos theory as well as its history to the broad public. Initially the domain of a few, isolated individuals, chaos theory progressively emerged as a transdisciplinary and institutional discipline, mainly under the name of nonlinear systems analysis. Alluding to Thomas Kuhn's concept of a paradigm shift exposed in The Structure of Scientific Revolutions (1962), many \"chaologists\" (as some described themselves) claimed that this new theory was an example of such a shift, a thesis upheld by Gleick.",
"title": "History"
},
{
"paragraph_id": 57,
"text": "The availability of cheaper, more powerful computers broadens the applicability of chaos theory. Currently, chaos theory remains an active area of research, involving many different disciplines such as mathematics, topology, physics, social systems, population modeling, biology, meteorology, astrophysics, information theory, computational neuroscience, pandemic crisis management, etc.",
"title": "History"
},
{
"paragraph_id": 58,
"text": "Throughout his career, Professor Lorenz authored a total of 61 research papers, out of which 58 were solely authored by him. Commencing with the 1960 conference in Japan, Lorenz embarked on a journey of developing diverse models aimed at uncovering the SDIC and chaotic features. A recent review of Lorenz's model progression spanning from 1960 to 2008 revealed his adeptness at employing varied physical systems to illustrate chaotic phenomena. These systems encompassed Quasi-geostrophic systems, the Conservative Vorticity Equation, the Rayleigh-Bénard Convection Equations, and the Shallow Water Equations. Moreover, Lorenz can be credited with the early application of the logistic map to explore chaotic solutions, a milestone he achieved ahead of his colleagues (e.g. Lorenz 1964 ).",
"title": "Lorenz's pioneering contributions to chaotic modeling"
},
{
"paragraph_id": 59,
"text": "In 1972, Lorenz coined the term \"butterfly effect\" as a metaphor to discuss whether a small perturbation could eventually create a tornado with a three-dimensional, organized, and coherent structure. While connected to the original butterfly effect based on sensitive dependence on initial conditions, its metaphorical variant carries distinct nuances. To commemorate this milestone, a reprint book containing invited papers that deepen our understanding of both butterfly effects was officially published to celebrate the 50th anniversary of the metaphorical butterfly effect.",
"title": "Lorenz's pioneering contributions to chaotic modeling"
},
{
"paragraph_id": 60,
"text": "The sensitive dependence on initial conditions (i.e., butterfly effect) has been illustrated using the following folklore:",
"title": "A popular but inaccurate analogy for chaos"
},
{
"paragraph_id": 61,
"text": "For want of a nail, the shoe was lost.",
"title": "A popular but inaccurate analogy for chaos"
},
{
"paragraph_id": 62,
"text": "For want of a shoe, the horse was lost.",
"title": "A popular but inaccurate analogy for chaos"
},
{
"paragraph_id": 63,
"text": "For want of a horse, the rider was lost.",
"title": "A popular but inaccurate analogy for chaos"
},
{
"paragraph_id": 64,
"text": "For want of a rider, the battle was lost.",
"title": "A popular but inaccurate analogy for chaos"
},
{
"paragraph_id": 65,
"text": "For want of a battle, the kingdom was lost.",
"title": "A popular but inaccurate analogy for chaos"
},
{
"paragraph_id": 66,
"text": "And all for the want of a horseshoe nail.",
"title": "A popular but inaccurate analogy for chaos"
},
{
"paragraph_id": 67,
"text": "Based on the above, many people mistakenly believe that the impact of a tiny initial perturbation monotonically increases with time and that any tiny perturbation can eventually produce a large impact on numerical integrations. However, in 2008, Lorenz stated that he did not feel that this verse described true chaos but that it better illustrated the simpler phenomenon of instability and that the verse implicitly suggests that subsequent small events will not reverse the outcome (Lorenz, 2008 ). Based on the analysis, the verse only indicates divergence, not boundedness. Boundedness is important for the finite size of a butterfly pattern. In a recent study, the characteristic of the aforementioned verse was recently denoted as \"finite-time sensitive dependence\".",
"title": "A popular but inaccurate analogy for chaos"
},
{
"paragraph_id": 68,
"text": "Although chaos theory was born from observing weather patterns, it has become applicable to a variety of other situations. Some areas benefiting from chaos theory today are geology, mathematics, biology, computer science, economics, engineering, finance, meteorology, philosophy, anthropology, physics, politics, population dynamics, and robotics. A few categories are listed below with examples, but this is by no means a comprehensive list as new applications are appearing.",
"title": "Applications"
},
{
"paragraph_id": 69,
"text": "Chaos theory has been used for many years in cryptography. In the past few decades, chaos and nonlinear dynamics have been used in the design of hundreds of cryptographic primitives. These algorithms include image encryption algorithms, hash functions, secure pseudo-random number generators, stream ciphers, watermarking, and steganography. The majority of these algorithms are based on uni-modal chaotic maps and a big portion of these algorithms use the control parameters and the initial condition of the chaotic maps as their keys. From a wider perspective, without loss of generality, the similarities between the chaotic maps and the cryptographic systems is the main motivation for the design of chaos based cryptographic algorithms. One type of encryption, secret key or symmetric key, relies on diffusion and confusion, which is modeled well by chaos theory. Another type of computing, DNA computing, when paired with chaos theory, offers a way to encrypt images and other information. Many of the DNA-Chaos cryptographic algorithms are proven to be either not secure, or the technique applied is suggested to be not efficient.",
"title": "Applications"
},
{
"paragraph_id": 70,
"text": "Robotics is another area that has recently benefited from chaos theory. Instead of robots acting in a trial-and-error type of refinement to interact with their environment, chaos theory has been used to build a predictive model. Chaotic dynamics have been exhibited by passive walking biped robots.",
"title": "Applications"
},
{
"paragraph_id": 71,
"text": "For over a hundred years, biologists have been keeping track of populations of different species with population models. Most models are continuous, but recently scientists have been able to implement chaotic models in certain populations. For example, a study on models of Canadian lynx showed there was chaotic behavior in the population growth. Chaos can also be found in ecological systems, such as hydrology. While a chaotic model for hydrology has its shortcomings, there is still much to learn from looking at the data through the lens of chaos theory. Another biological application is found in cardiotocography. Fetal surveillance is a delicate balance of obtaining accurate information while being as noninvasive as possible. Better models of warning signs of fetal hypoxia can be obtained through chaotic modeling.",
"title": "Applications"
},
{
"paragraph_id": 72,
"text": "As Perry points out, modeling of chaotic time series in ecology is helped by constraint. There is always potential difficulty in distinguishing real chaos from chaos that is only in the model. Hence both constraint in the model and or duplicate time series data for comparison will be helpful in constraining the model to something close to the reality, for example Perry & Wall 1984. Gene-for-gene co-evolution sometimes shows chaotic dynamics in allele frequencies. Adding variables exaggerates this: Chaos is more common in models incorporating additional variables to reflect additional facets of real populations. Robert M. May himself did some of these foundational crop co-evolution studies, and this in turn helped shape the entire field. Even for a steady environment, merely combining one crop and one pathogen may result in quasi-periodic- or chaotic- oscillations in pathogen population.",
"title": "Applications"
},
{
"paragraph_id": 73,
"text": "It is possible that economic models can also be improved through an application of chaos theory, but predicting the health of an economic system and what factors influence it most is an extremely complex task. Economic and financial systems are fundamentally different from those in the classical natural sciences since the former are inherently stochastic in nature, as they result from the interactions of people, and thus pure deterministic models are unlikely to provide accurate representations of the data. The empirical literature that tests for chaos in economics and finance presents very mixed results, in part due to confusion between specific tests for chaos and more general tests for non-linear relationships.",
"title": "Applications"
},
{
"paragraph_id": 74,
"text": "Chaos could be found in economics by the means of recurrence quantification analysis. In fact, Orlando et al. by the means of the so-called recurrence quantification correlation index were able detect hidden changes in time series. Then, the same technique was employed to detect transitions from laminar (regular) to turbulent (chaotic) phases as well as differences between macroeconomic variables and highlight hidden features of economic dynamics. Finally, chaos theory could help in modeling how an economy operates as well as in embedding shocks due to external events such as COVID-19.",
"title": "Applications"
},
{
"paragraph_id": 75,
"text": "In chemistry, predicting gas solubility is essential to manufacturing polymers, but models using particle swarm optimization (PSO) tend to converge to the wrong points. An improved version of PSO has been created by introducing chaos, which keeps the simulations from getting stuck. In celestial mechanics, especially when observing asteroids, applying chaos theory leads to better predictions about when these objects will approach Earth and other planets. Four of the five moons of Pluto rotate chaotically. In quantum physics and electrical engineering, the study of large arrays of Josephson junctions benefitted greatly from chaos theory. Closer to home, coal mines have always been dangerous places where frequent natural gas leaks cause many deaths. Until recently, there was no reliable way to predict when they would occur. But these gas leaks have chaotic tendencies that, when properly modeled, can be predicted fairly accurately.",
"title": "Applications"
},
{
"paragraph_id": 76,
"text": "Chaos theory can be applied outside of the natural sciences, but historically nearly all such studies have suffered from lack of reproducibility; poor external validity; and/or inattention to cross-validation, resulting in poor predictive accuracy (if out-of-sample prediction has even been attempted). Glass and Mandell and Selz have found that no EEG study has as yet indicated the presence of strange attractors or other signs of chaotic behavior.",
"title": "Applications"
},
{
"paragraph_id": 77,
"text": "Researchers have continued to apply chaos theory to psychology. For example, in modeling group behavior in which heterogeneous members may behave as if sharing to different degrees what in Wilfred Bion's theory is a basic assumption, researchers have found that the group dynamic is the result of the individual dynamics of the members: each individual reproduces the group dynamics in a different scale, and the chaotic behavior of the group is reflected in each member.",
"title": "Applications"
},
{
"paragraph_id": 78,
"text": "Redington and Reidbord (1992) attempted to demonstrate that the human heart could display chaotic traits. They monitored the changes in between-heartbeat intervals for a single psychotherapy patient as she moved through periods of varying emotional intensity during a therapy session. Results were admittedly inconclusive. Not only were there ambiguities in the various plots the authors produced to purportedly show evidence of chaotic dynamics (spectral analysis, phase trajectory, and autocorrelation plots), but also when they attempted to compute a Lyapunov exponent as more definitive confirmation of chaotic behavior, the authors found they could not reliably do so.",
"title": "Applications"
},
{
"paragraph_id": 79,
"text": "In their 1995 paper, Metcalf and Allen maintained that they uncovered in animal behavior a pattern of period doubling leading to chaos. The authors examined a well-known response called schedule-induced polydipsia, by which an animal deprived of food for certain lengths of time will drink unusual amounts of water when the food is at last presented. The control parameter (r) operating here was the length of the interval between feedings, once resumed. The authors were careful to test a large number of animals and to include many replications, and they designed their experiment so as to rule out the likelihood that changes in response patterns were caused by different starting places for r.",
"title": "Applications"
},
{
"paragraph_id": 80,
"text": "Time series and first delay plots provide the best support for the claims made, showing a fairly clear march from periodicity to irregularity as the feeding times were increased. The various phase trajectory plots and spectral analyses, on the other hand, do not match up well enough with the other graphs or with the overall theory to lead inexorably to a chaotic diagnosis. For example, the phase trajectories do not show a definite progression towards greater and greater complexity (and away from periodicity); the process seems quite muddied. Also, where Metcalf and Allen saw periods of two and six in their spectral plots, there is room for alternative interpretations. All of this ambiguity necessitate some serpentine, post-hoc explanation to show that results fit a chaotic model.",
"title": "Applications"
},
{
"paragraph_id": 81,
"text": "By adapting a model of career counseling to include a chaotic interpretation of the relationship between employees and the job market, Amundson and Bright found that better suggestions can be made to people struggling with career decisions. Modern organizations are increasingly seen as open complex adaptive systems with fundamental natural nonlinear structures, subject to internal and external forces that may contribute chaos. For instance, team building and group development is increasingly being researched as an inherently unpredictable system, as the uncertainty of different individuals meeting for the first time makes the trajectory of the team unknowable.",
"title": "Applications"
},
{
"paragraph_id": 82,
"text": "Some say the chaos metaphor—used in verbal theories—grounded on mathematical models and psychological aspects of human behavior provides helpful insights to describing the complexity of small work groups, that go beyond the metaphor itself.",
"title": "Applications"
},
{
"paragraph_id": 83,
"text": "Traffic forecasting may benefit from applications of chaos theory. Better predictions of when a congestion will occur would allow measures to be taken to disperse it before it would have occurred. Combining chaos theory principles with a few other methods has led to a more accurate short-term prediction model (see the plot of the BML traffic model at right).",
"title": "Applications"
},
{
"paragraph_id": 84,
"text": "Chaos theory has been applied to environmental water cycle data (also hydrological data), such as rainfall and streamflow. These studies have yielded controversial results, because the methods for detecting a chaotic signature are often relatively subjective. Early studies tended to \"succeed\" in finding chaos, whereas subsequent studies and meta-analyses called those studies into question and provided explanations for why these datasets are not likely to have low-dimension chaotic dynamics.",
"title": "Applications"
},
{
"paragraph_id": 85,
"text": "In art (predominately art theory) a possible postpostmodern era has been outlined with emphasis on multiple narratives and the notion that every fictional angle is a possibility. In part this is therefor of a bisociate (trissociative) discourse and can be explained within emphasis on an institutional interchange of subjectivistic agents.",
"title": "Applications"
},
{
"paragraph_id": 86,
"text": "Examples of chaotic systems",
"title": "See also"
},
{
"paragraph_id": 87,
"text": "Other related topics",
"title": "See also"
},
{
"paragraph_id": 88,
"text": "People",
"title": "See also"
}
] | Chaos theory is an interdisciplinary area of scientific study and branch of mathematics focused on underlying patterns and deterministic laws of dynamical systems that are highly sensitive to initial conditions, and were once thought to have completely random states of disorder and irregularities. Chaos theory states that within the apparent randomness of chaotic complex systems, there are underlying patterns, interconnection, constant feedback loops, repetition, self-similarity, fractals, and self-organization. The butterfly effect, an underlying principle of chaos, describes how a small change in one state of a deterministic nonlinear system can result in large differences in a later state. A metaphor for this behavior is that a butterfly flapping its wings in Texas can cause a tornado in Brazil. Small differences in initial conditions, such as those due to errors in measurements or due to rounding errors in numerical computation, can yield widely diverging outcomes for such dynamical systems, rendering long-term prediction of their behavior impossible in general. This can happen even though these systems are deterministic, meaning that their future behavior follows a unique evolution and is fully determined by their initial conditions, with no random elements involved. In other words, the deterministic nature of these systems does not make them predictable. This behavior is known as deterministic chaos, or simply chaos. The theory was summarized by Edward Lorenz as: Chaotic behavior exists in many natural systems, including fluid flow, heartbeat irregularities, weather, and climate. It also occurs spontaneously in some systems with artificial components, such as road traffic. This behavior can be studied through the analysis of a chaotic mathematical model, or through analytical techniques such as recurrence plots and Poincaré maps. Chaos theory has applications in a variety of disciplines, including meteorology, anthropology, sociology, environmental science, computer science, engineering, economics, ecology, and pandemic crisis management. The theory formed the basis for such fields of study as complex dynamical systems, edge of chaos theory, and self-assembly processes. | 2001-09-24T18:10:05Z | 2023-12-18T02:01:08Z | [
"Template:Springer",
"Template:Self-published inline",
"Template:Cite journal",
"Template:Linktext",
"Template:Self-published source",
"Template:Dead link",
"Template:Library resources box",
"Template:Cite book",
"Template:Harvnb",
"Template:Webarchive",
"Template:Div col",
"Template:Commons category",
"Template:Free-content attribution",
"Template:Patterns in nature",
"Template:Other uses",
"Template:RP",
"Template:ISBN",
"Template:Blockquote",
"Template:Portal",
"Template:Reflist",
"Template:Cite web",
"Template:Short description",
"Template:Nowrap",
"Template:Main",
"Template:Convert",
"Template:Rp",
"Template:Citation",
"Template:Authority control",
"Template:Citation needed",
"Template:Div col end",
"Template:Chaos theory"
] | https://en.wikipedia.org/wiki/Chaos_theory |
6,298 | Cupola | In architecture, a cupola (/ˈk(j)uːpələ/) is a relatively small, most often dome-like, tall structure on top of a building. Often used to provide a lookout or to admit light and air, it usually crowns a larger roof or dome.
The word derives, via Italian, from lower Latin cupula (classical Latin cupella), from Ancient Greek κύπελλον (kúpellon) 'small cup' (Latin cupa), indicating a vault resembling an upside-down cup.
The cupola evolved during the Renaissance from the older oculus. Being weatherproof, the cupola was better suited to the wetter climates of northern Europe. The chhatri, seen in Indian architecture, fits the definition of a cupola when it is used atop a larger structure.
Cupolas often serve as a belfry, belvedere, or roof lantern above a main roof. In other cases they may crown a spire, tower, or turret. Barns often have cupolas for ventilation.
Cupolas can also appear as small buildings in their own right.
The square, dome-like segment of a North American railroad train caboose that contains the second-level or "angel" seats is also called a cupola.
The term cupola can also refer to the protrusions atop an armoured fighting vehicle due to their distinctive dome-like appearance. They allow crew or personnel to observe, offering very good all round vision, or even field weaponry, without being exposed to incoming fire. Later designs, however, became progressively flatter and less prominent as technology evolved to allow designers to reduce the profile of their vehicles. | [
{
"paragraph_id": 0,
"text": "In architecture, a cupola (/ˈk(j)uːpələ/) is a relatively small, most often dome-like, tall structure on top of a building. Often used to provide a lookout or to admit light and air, it usually crowns a larger roof or dome.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The word derives, via Italian, from lower Latin cupula (classical Latin cupella), from Ancient Greek κύπελλον (kúpellon) 'small cup' (Latin cupa), indicating a vault resembling an upside-down cup.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The cupola evolved during the Renaissance from the older oculus. Being weatherproof, the cupola was better suited to the wetter climates of northern Europe. The chhatri, seen in Indian architecture, fits the definition of a cupola when it is used atop a larger structure.",
"title": "Background"
},
{
"paragraph_id": 3,
"text": "Cupolas often serve as a belfry, belvedere, or roof lantern above a main roof. In other cases they may crown a spire, tower, or turret. Barns often have cupolas for ventilation.",
"title": "Background"
},
{
"paragraph_id": 4,
"text": "Cupolas can also appear as small buildings in their own right.",
"title": "Background"
},
{
"paragraph_id": 5,
"text": "The square, dome-like segment of a North American railroad train caboose that contains the second-level or \"angel\" seats is also called a cupola.",
"title": "Background"
},
{
"paragraph_id": 6,
"text": "The term cupola can also refer to the protrusions atop an armoured fighting vehicle due to their distinctive dome-like appearance. They allow crew or personnel to observe, offering very good all round vision, or even field weaponry, without being exposed to incoming fire. Later designs, however, became progressively flatter and less prominent as technology evolved to allow designers to reduce the profile of their vehicles.",
"title": "On armoured vehicles"
}
] | In architecture, a cupola is a relatively small, most often dome-like, tall structure on top of a building. Often used to provide a lookout or to admit light and air, it usually crowns a larger roof or dome. The word derives, via Italian, from lower Latin cupula, from Ancient Greek κύπελλον (kúpellon) 'small cup', indicating a vault resembling an upside-down cup. | 2001-09-08T20:12:03Z | 2023-12-27T18:03:18Z | [
"Template:Short description",
"Template:Commons category",
"Template:Cite book",
"Template:Portal",
"Template:History of architecture",
"Template:Notelist",
"Template:Cite web",
"Template:Citation needed",
"Template:Clear",
"Template:Reflist",
"Template:Cite Merriam-Webster",
"Template:Cite journal",
"Template:IPAc-en",
"Template:Etymology",
"Template:Cite American Heritage Dictionary",
"Template:Other uses",
"Template:Efn"
] | https://en.wikipedia.org/wiki/Cupola |
6,299 | Chupacabra | The chupacabra or chupacabras (Spanish pronunciation: [tʃupaˈkaβɾas], literally 'goat-sucker'; from Spanish: chupa, 'sucks', and cabras, 'goats') is a legendary creature in the folklore of parts of the Americas. The name comes from the animal's reported vampirism—the chupacabra is said to attack and drink the blood of livestock, including goats.
Physical descriptions of the creature vary. In Puerto Rico and in Hispanic America it is generally described as a heavy creature, reptilian and alien-like, roughly the size of a small bear, and with a row of spines reaching from the neck to the base of the tail, while in the Southwestern United States it is depicted as more dog-like.
Initial sightings and accompanying descriptions first occurred in Puerto Rico in 1995. The creature has since been reported as far north as Maine, as far south as Chile, and even outside the Americas in countries like Russia and Philippines. All of the reports are anecdotal and have been disregarded as uncorroborated or lacking evidence. Sightings in northern Mexico and the southern United States have been verified as canids afflicted by mange.
Chupacabras can be literally translated as 'goat-sucker', from chupar ('to suck') and cabras ('goats'). It is known as both chupacabras and chupacabra throughout the Americas, with the former being the original name, and the latter a regularization. The name is attributed to Puerto Rican comedian Silverio Pérez, who coined the label in 1995 while commenting on the attacks as a San Juan radio deejay.
In 1975, a series of livestock killings in the small town of Moca, Puerto Rico were attributed to el vampiro de Moca ('the vampire of Moca'). Initially, it was suspected that the killings were committed by a Satanic cult; later more killings were reported around the island, and many farms reported loss of animal life. Each of the animals was reported to have had its body bled dry through a series of small circular incisions.
The first reported attack eventually attributed to the actual chupacabras occurred in March 1995. Eight sheep were discovered dead in Puerto Rico, each with three puncture wounds in the chest area and reportedly completely drained of blood. A few months later, in August, an eyewitness named Madelyne Tolentino reported seeing the creature in the Puerto Rican town of Canóvanas, where as many as 150 farm animals and pets were reportedly killed.
Puerto Rican comedian and entrepreneur Silverio Pérez is credited with coining the term chupacabras soon after the first incidents were reported in the press. Shortly after the first reported incidents in Puerto Rico, other animal deaths were reported in other countries, such as Argentina, Bolivia, Brazil, Chile, Colombia, Dominican Republic, El Salvador, Honduras, Mexico, Nicaragua, Panama, Peru, and the United States.
In 2019 a video recorded by Mundo Ovni showed the results of a supposed attack on chickens in the Seburuquillo sector of Lares, Puerto Rico.
A five-year investigation by Benjamin Radford, documented in his 2011 book Tracking the Chupacabra, concluded that the description given by the original eyewitness in Puerto Rico, Madelyne Tolentino, was based on the creature Sil in the 1995 science-fiction horror film Species. The alien creature Sil is nearly identical to Tolentino's chupacabra eyewitness account and she had seen the movie before her report: "It was a creature that looked like the chupacabra, with spines on its back and all... The resemblance to the chupacabra was really impressive", Tolentino reported. Radford revealed that Tolentino "believed that the creatures and events she saw in Species were happening in reality in Puerto Rico at the time", and therefore concludes that "the most important chupacabra description cannot be trusted". This, Radford believes, seriously undermines the credibility of the chupacabra as a real animal.
The reports of blood-sucking by the chupacabra were never confirmed by a necropsy, the only way to conclude that the animal was drained of blood. Dr. David Morales, a Puerto Rican veterinarian with the Department of Agriculture, analyzed 300 reported victims of the chupacabra and found that they had not been bled dry.
Radford divided the chupacabra reports into two categories: the reports from Puerto Rico and Latin America, where animals were attacked and it is supposed their blood was extracted; and the reports in the United States of mammals, mostly dogs and coyotes with mange, that people call "chupacabra" due to their unusual appearance.
In 2010, University of Michigan biologist Barry O'Connor concluded that all the chupacabra reports in the United States were simply coyotes infected with the parasite Sarcoptes scabiei, whose symptoms would explain most of the features of the chupacabra: they would be left with little fur, thickened skin, and a rank odor. O'Connor theorized that the attacks on goats occurred "because these animals are greatly weakened, [so] they're going to have a hard time hunting. So they may be forced into attacking livestock because it's easier than running down a rabbit or a deer." Both dogs and coyotes can kill and not consume the prey, either because they are inexperienced, or due to injury or difficulty in killing the prey. The prey can survive the attack and die afterwards from internal bleeding or circulatory shock. The presence of two holes in the neck, corresponding with the canine teeth, are to be expected since this is the only way that most land carnivores have to catch their prey. There are reports of stray Mexican hairless dogs being mistaken for chupacabras.
The most common description of the chupacabra is that of a reptile-like creature, said to have leathery or scaly greenish-gray skin and sharp spines or quills running down its back. It is said to be approximately 3 to 4 feet (0.9 to 1.2 m) high, and stands and hops in a fashion similar to that of a kangaroo. This description was the chief one given to the few Puerto Rican reports in 1995 that claimed to have sighted the creature, with similar reports in parts of Chile and Argentina following.
Another common description of the chupacabra is of a strange breed of wild dog. This form is mostly hairless and has a pronounced spinal ridge, unusually pronounced eye sockets, fangs, and claws. This description started to appear in the early 2000s from reports trailing north from the Yucatán Peninsula, northern Mexico, and then into the United States; becoming the predominant description since. Unlike conventional predators, the chupacabra is said to drain all of the animal's blood (and sometimes organs) usually through three holes in the shape of a downwards-pointing triangle, but sometimes through only one or two holes.
The chupacabra panic first started in late 1995, Puerto Rico: farmers were mass reporting the mysterious killings of various livestock. In these reports, the farmers recalled two puncture wounds on the animal carcasses. Chupacabra killings were soon associated with a seemingly untouched animal carcass other than puncture wounds which were said to be used to suck the blood out of the victim. Reports of such killings began to spread around and eventually out of the country, reaching areas such as Mexico, Brazil, Chile, and the Southern area of the United States.
Most notably, these areas experience frequent, and extreme dry seasons; in the cases of the Puerto Rican reports of 1995 and the Mexican reports of 1996, both countries were currently experiencing or dealing with the aftermath of severe droughts. Investigations carried out in both countries at this time noted a certain dramatic violence in these killings. These environmental conditions could provide a simple explanation for the livestock killings: wild predators losing their usual prey to the drought, therefore being forced to hunt the livestock of farmers for sustenance. Thus, the same theory can be applied to many of the other ‘chupacabra’ attacks: that the dry weather had created a more competitive environment for native predators, leading them to prey on livestock to survive. Such an idea can also explain the increased violence in the killings; hungry and desperate predators are driven to hunt livestock to avoid starvation, causing an increase in both the number of livestock killings, and the viciousness of each one.
Evidence of such is provided in page 179 of Benjamin Radford’s book, Tracking the Chupacabra: The Vampire Beast in Fact, Fiction, and Folklore. Radford’s chart highlights ten significant reports of chupacabra attacks, seven of which had a carcass recovered and examined; these autopsies concluded the causes of death as various animal attacks, as displayed though the animal DNA found on the carcasses. Radford provides further evidence in pages 161-162 of his book, displaying animals who are proven to have fallen victim to regular coyote attacks; thus, explaining that it is not unusual for an animal carcass to be left uneaten while only displaying puncture wounds and/or minimal signs of attack.
The plausibility of the chupacabra’s existence is also discredited by the varying descriptions of the creature. Depending on the reported sighting, the creature is described with thick skin or fur, wings or no wings, a long tail or no tail, is bat-like, dog-like, or even alien-like. Evidently, the chupacabra has a wide variety of descriptions; to the point where it is hard to believe that all the sightings are of the same creature. A very likely explanation for this phenomenon is that individuals who had heard of the newly popular chupacabra had the creature’s name fresh in their mind before they happened to see a strange looking animal. They then resort to make sense of their encounter by labelling it as the recently ‘discovered’ monster, instead of a more realistic explanation. For example, some scientists hypothesize that what many believe to be a chupacabra is a wild or domestic dog affected by mange, a disease causing a thick buildup of skin and hair loss.
The "Ozark Howler", a large bear-like animal, is the subject of a similar legend.
The Peuchens of Chile also share similarities in their supposed habits, but instead of being dog-like they are described as winged snakes. This legend may have originated from the vampire bat, an animal endemic to the region.
In the Philippines the Sigbin shares many of the chupacabra's descriptions.
"Grunches" is a legend in New Orleans that gets its name from a lovers' lane called Grunch Road, between the Mississippi River and the Gulf of Mexico. The road was said to be inhabited by creatures called "grunches", similar in appearance to the Chupacabra.
In 2018 there were reports of suspected chupacabras in Manipur, India. Many domestic animals and poultry were killed in a manner similar to other chupacabra attacks, and several people reported that they had seen creatures. Forensic experts opined that street dogs were responsible for mass killing of domestic animals and poultry after studying the remnants of a corpse. | [
{
"paragraph_id": 0,
"text": "The chupacabra or chupacabras (Spanish pronunciation: [tʃupaˈkaβɾas], literally 'goat-sucker'; from Spanish: chupa, 'sucks', and cabras, 'goats') is a legendary creature in the folklore of parts of the Americas. The name comes from the animal's reported vampirism—the chupacabra is said to attack and drink the blood of livestock, including goats.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Physical descriptions of the creature vary. In Puerto Rico and in Hispanic America it is generally described as a heavy creature, reptilian and alien-like, roughly the size of a small bear, and with a row of spines reaching from the neck to the base of the tail, while in the Southwestern United States it is depicted as more dog-like.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Initial sightings and accompanying descriptions first occurred in Puerto Rico in 1995. The creature has since been reported as far north as Maine, as far south as Chile, and even outside the Americas in countries like Russia and Philippines. All of the reports are anecdotal and have been disregarded as uncorroborated or lacking evidence. Sightings in northern Mexico and the southern United States have been verified as canids afflicted by mange.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Chupacabras can be literally translated as 'goat-sucker', from chupar ('to suck') and cabras ('goats'). It is known as both chupacabras and chupacabra throughout the Americas, with the former being the original name, and the latter a regularization. The name is attributed to Puerto Rican comedian Silverio Pérez, who coined the label in 1995 while commenting on the attacks as a San Juan radio deejay.",
"title": "Name"
},
{
"paragraph_id": 4,
"text": "In 1975, a series of livestock killings in the small town of Moca, Puerto Rico were attributed to el vampiro de Moca ('the vampire of Moca'). Initially, it was suspected that the killings were committed by a Satanic cult; later more killings were reported around the island, and many farms reported loss of animal life. Each of the animals was reported to have had its body bled dry through a series of small circular incisions.",
"title": "History"
},
{
"paragraph_id": 5,
"text": "The first reported attack eventually attributed to the actual chupacabras occurred in March 1995. Eight sheep were discovered dead in Puerto Rico, each with three puncture wounds in the chest area and reportedly completely drained of blood. A few months later, in August, an eyewitness named Madelyne Tolentino reported seeing the creature in the Puerto Rican town of Canóvanas, where as many as 150 farm animals and pets were reportedly killed.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "Puerto Rican comedian and entrepreneur Silverio Pérez is credited with coining the term chupacabras soon after the first incidents were reported in the press. Shortly after the first reported incidents in Puerto Rico, other animal deaths were reported in other countries, such as Argentina, Bolivia, Brazil, Chile, Colombia, Dominican Republic, El Salvador, Honduras, Mexico, Nicaragua, Panama, Peru, and the United States.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "In 2019 a video recorded by Mundo Ovni showed the results of a supposed attack on chickens in the Seburuquillo sector of Lares, Puerto Rico.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "A five-year investigation by Benjamin Radford, documented in his 2011 book Tracking the Chupacabra, concluded that the description given by the original eyewitness in Puerto Rico, Madelyne Tolentino, was based on the creature Sil in the 1995 science-fiction horror film Species. The alien creature Sil is nearly identical to Tolentino's chupacabra eyewitness account and she had seen the movie before her report: \"It was a creature that looked like the chupacabra, with spines on its back and all... The resemblance to the chupacabra was really impressive\", Tolentino reported. Radford revealed that Tolentino \"believed that the creatures and events she saw in Species were happening in reality in Puerto Rico at the time\", and therefore concludes that \"the most important chupacabra description cannot be trusted\". This, Radford believes, seriously undermines the credibility of the chupacabra as a real animal.",
"title": "Reputed origin"
},
{
"paragraph_id": 9,
"text": "The reports of blood-sucking by the chupacabra were never confirmed by a necropsy, the only way to conclude that the animal was drained of blood. Dr. David Morales, a Puerto Rican veterinarian with the Department of Agriculture, analyzed 300 reported victims of the chupacabra and found that they had not been bled dry.",
"title": "Reputed origin"
},
{
"paragraph_id": 10,
"text": "Radford divided the chupacabra reports into two categories: the reports from Puerto Rico and Latin America, where animals were attacked and it is supposed their blood was extracted; and the reports in the United States of mammals, mostly dogs and coyotes with mange, that people call \"chupacabra\" due to their unusual appearance.",
"title": "Reputed origin"
},
{
"paragraph_id": 11,
"text": "In 2010, University of Michigan biologist Barry O'Connor concluded that all the chupacabra reports in the United States were simply coyotes infected with the parasite Sarcoptes scabiei, whose symptoms would explain most of the features of the chupacabra: they would be left with little fur, thickened skin, and a rank odor. O'Connor theorized that the attacks on goats occurred \"because these animals are greatly weakened, [so] they're going to have a hard time hunting. So they may be forced into attacking livestock because it's easier than running down a rabbit or a deer.\" Both dogs and coyotes can kill and not consume the prey, either because they are inexperienced, or due to injury or difficulty in killing the prey. The prey can survive the attack and die afterwards from internal bleeding or circulatory shock. The presence of two holes in the neck, corresponding with the canine teeth, are to be expected since this is the only way that most land carnivores have to catch their prey. There are reports of stray Mexican hairless dogs being mistaken for chupacabras.",
"title": "Reputed origin"
},
{
"paragraph_id": 12,
"text": "The most common description of the chupacabra is that of a reptile-like creature, said to have leathery or scaly greenish-gray skin and sharp spines or quills running down its back. It is said to be approximately 3 to 4 feet (0.9 to 1.2 m) high, and stands and hops in a fashion similar to that of a kangaroo. This description was the chief one given to the few Puerto Rican reports in 1995 that claimed to have sighted the creature, with similar reports in parts of Chile and Argentina following.",
"title": "Appearance"
},
{
"paragraph_id": 13,
"text": "Another common description of the chupacabra is of a strange breed of wild dog. This form is mostly hairless and has a pronounced spinal ridge, unusually pronounced eye sockets, fangs, and claws. This description started to appear in the early 2000s from reports trailing north from the Yucatán Peninsula, northern Mexico, and then into the United States; becoming the predominant description since. Unlike conventional predators, the chupacabra is said to drain all of the animal's blood (and sometimes organs) usually through three holes in the shape of a downwards-pointing triangle, but sometimes through only one or two holes.",
"title": "Appearance"
},
{
"paragraph_id": 14,
"text": "The chupacabra panic first started in late 1995, Puerto Rico: farmers were mass reporting the mysterious killings of various livestock. In these reports, the farmers recalled two puncture wounds on the animal carcasses. Chupacabra killings were soon associated with a seemingly untouched animal carcass other than puncture wounds which were said to be used to suck the blood out of the victim. Reports of such killings began to spread around and eventually out of the country, reaching areas such as Mexico, Brazil, Chile, and the Southern area of the United States.",
"title": "Plausibility of Existence"
},
{
"paragraph_id": 15,
"text": "Most notably, these areas experience frequent, and extreme dry seasons; in the cases of the Puerto Rican reports of 1995 and the Mexican reports of 1996, both countries were currently experiencing or dealing with the aftermath of severe droughts. Investigations carried out in both countries at this time noted a certain dramatic violence in these killings. These environmental conditions could provide a simple explanation for the livestock killings: wild predators losing their usual prey to the drought, therefore being forced to hunt the livestock of farmers for sustenance. Thus, the same theory can be applied to many of the other ‘chupacabra’ attacks: that the dry weather had created a more competitive environment for native predators, leading them to prey on livestock to survive. Such an idea can also explain the increased violence in the killings; hungry and desperate predators are driven to hunt livestock to avoid starvation, causing an increase in both the number of livestock killings, and the viciousness of each one.",
"title": "Plausibility of Existence"
},
{
"paragraph_id": 16,
"text": "Evidence of such is provided in page 179 of Benjamin Radford’s book, Tracking the Chupacabra: The Vampire Beast in Fact, Fiction, and Folklore. Radford’s chart highlights ten significant reports of chupacabra attacks, seven of which had a carcass recovered and examined; these autopsies concluded the causes of death as various animal attacks, as displayed though the animal DNA found on the carcasses. Radford provides further evidence in pages 161-162 of his book, displaying animals who are proven to have fallen victim to regular coyote attacks; thus, explaining that it is not unusual for an animal carcass to be left uneaten while only displaying puncture wounds and/or minimal signs of attack.",
"title": "Plausibility of Existence"
},
{
"paragraph_id": 17,
"text": "The plausibility of the chupacabra’s existence is also discredited by the varying descriptions of the creature. Depending on the reported sighting, the creature is described with thick skin or fur, wings or no wings, a long tail or no tail, is bat-like, dog-like, or even alien-like. Evidently, the chupacabra has a wide variety of descriptions; to the point where it is hard to believe that all the sightings are of the same creature. A very likely explanation for this phenomenon is that individuals who had heard of the newly popular chupacabra had the creature’s name fresh in their mind before they happened to see a strange looking animal. They then resort to make sense of their encounter by labelling it as the recently ‘discovered’ monster, instead of a more realistic explanation. For example, some scientists hypothesize that what many believe to be a chupacabra is a wild or domestic dog affected by mange, a disease causing a thick buildup of skin and hair loss.",
"title": "Plausibility of Existence"
},
{
"paragraph_id": 18,
"text": "The \"Ozark Howler\", a large bear-like animal, is the subject of a similar legend.",
"title": "Related legends"
},
{
"paragraph_id": 19,
"text": "The Peuchens of Chile also share similarities in their supposed habits, but instead of being dog-like they are described as winged snakes. This legend may have originated from the vampire bat, an animal endemic to the region.",
"title": "Related legends"
},
{
"paragraph_id": 20,
"text": "In the Philippines the Sigbin shares many of the chupacabra's descriptions.",
"title": "Related legends"
},
{
"paragraph_id": 21,
"text": "\"Grunches\" is a legend in New Orleans that gets its name from a lovers' lane called Grunch Road, between the Mississippi River and the Gulf of Mexico. The road was said to be inhabited by creatures called \"grunches\", similar in appearance to the Chupacabra.",
"title": "Related legends"
},
{
"paragraph_id": 22,
"text": "In 2018 there were reports of suspected chupacabras in Manipur, India. Many domestic animals and poultry were killed in a manner similar to other chupacabra attacks, and several people reported that they had seen creatures. Forensic experts opined that street dogs were responsible for mass killing of domestic animals and poultry after studying the remnants of a corpse.",
"title": "Related legends"
}
] | The chupacabra or chupacabras is a legendary creature in the folklore of parts of the Americas. The name comes from the animal's reported vampirism—the chupacabra is said to attack and drink the blood of livestock, including goats. Physical descriptions of the creature vary. In Puerto Rico and in Hispanic America it is generally described as a heavy creature, reptilian and alien-like, roughly the size of a small bear, and with a row of spines reaching from the neck to the base of the tail, while in the Southwestern United States it is depicted as more dog-like. Initial sightings and accompanying descriptions first occurred in Puerto Rico in 1995. The creature has since been reported as far north as Maine, as far south as Chile, and even outside the Americas in countries like Russia and Philippines. All of the reports are anecdotal and have been disregarded as uncorroborated or lacking evidence. Sightings in northern Mexico and the southern United States have been verified as canids afflicted by mange. | 2001-09-09T00:20:05Z | 2023-12-25T00:13:00Z | [
"Template:Use dmy dates",
"Template:Infobox mythical creature",
"Template:Sisterlinks",
"Template:Cite news",
"Template:Skeptoid",
"Template:Other uses",
"Template:Lang-es",
"Template:Cite book",
"Template:Cite AV media",
"Template:Cbignore",
"Template:Cite journal",
"Template:Short description",
"Template:Reflist",
"Template:Cite magazine",
"Template:Cite web",
"Template:Pp-semi-vandalism",
"Template:Paranormal",
"Template:IPA-es",
"Template:Lang",
"Template:Convert",
"Template:Rs"
] | https://en.wikipedia.org/wiki/Chupacabra |
6,309 | Cayuga Lake | Cayuga Lake (/kəˈjuːɡə/,/keɪˈjuːɡə/,/kaɪˈjuːɡə/) is the longest of central New York's glacial Finger Lakes, and is the second largest in surface area (marginally smaller than Seneca Lake) and second largest in volume. It is just under 39 miles (63 km) long. Its average width is 1.7 miles (2.8 km), and it is 3.5 mi wide (5.6 km) at its widest point, near Aurora. It is approximately 435 ft deep (133 m) at its deepest point, and has over 95 miles (153 km) of shoreline.
The lake is named after the indigenous Cayuga people.
The city of Ithaca, site of Ithaca College and Cornell University, is located at the southern end of Cayuga Lake.
Villages and settlements along the east shore of Cayuga Lake include Myers, King Ferry, Aurora, Levanna, Union Springs, and Cayuga. Settlements along the west shore of the lake include Sheldrake, Poplar Beach, and Canoga.
The lake has two small islands. One is near Union Springs, called Frontenac Island (northeast); this island is not inhabited. The other island, Canoga Island (northwest), is located near the town of Canoga. This island has several camps and is inhabited during the summer months. The only other island in any of the Finger Lakes is Skenoh Island in Canandaigua Lake.
Cayuga Lake is located at 42°41′17″N 76°42′8″W / 42.68806°N 76.70222°W / 42.68806; -76.70222; 116.4 meters (382 ft) above sea level. Its depth, with steep east and west sides and shallow north and south ends, is typical of the Finger Lakes, as they were carved by glaciers during the last ice age.
The water level is regulated by the Mud Lock at the north end of the lake. It is connected to Lake Ontario by the Erie Canal and Seneca Lake by the Seneca River. The lake is drawn down as winter approaches, to minimize ice damage and to maximize its capacity to store heavy spring runoff.
The north end is dominated by shallow mudflats. An important stopover for migratory birds, the mudflats and marsh are the location of the Montezuma National Wildlife Refuge. The southern end is also shallow and often freezes during the winter.
Cayuga Lake is very popular among recreational boaters. The Allan H. Treman State Marine Park, with a large state marina and boat launch, is located at the southern end of the lake in Ithaca. There are two yacht clubs on the western shore: Ithaca Yacht Club, a few miles north of Ithaca, and Red Jacket Yacht Club, just south of Canoga. There are several other marinas and boat launches, scattered along the lake shore.
Cayuga Lake is the source of drinking water for several communities, including Lansing, near the southern end of the lake along the east side, which draws water through the Bolton Point Water System. There are also several lake source cooling systems that are in operation on the lake, whereby cooler water is pumped from the depths of the lake, warmed, and circulated in a closed system back to the surface. One of these systems, which is operated by Cornell University and began operation in 2000, was controversial during the planning and building stages, due to its potential for having a negative environmental impact. However, all of the environmental impact reports and scientific studies have shown that the Cornell lake source cooling system has not yet had, and will not likely have any measurably significant environmental impact. Furthermore, Cornell's system pumps significantly less warm water back into the lake than others further north, which have been operating for decades, including the coal-fired power plant on the eastern shore.
The AES Coal Power plant was shut down in August 2019, and there are plans to convert it into a data center in the near future. The plant used to use Cayuga Lake as a cooling source. In the late 1960s, citizens successfully opposed the construction of an 830-MW nuclear power plant on the shore of Cayuga Lake.
Rod Serling named his production company Cayuga Productions, during the years of his TV series, The Twilight Zone. Serling and his family had a summer home at Cayuga Lake.
The fish population is managed and substantial sport fishing is practiced, with anglers targeting smelt, lake trout and smallmouth bass. Fish species present in the lake include lake trout, landlocked salmon, brown trout, rainbow trout, smallmouth bass, smelt, alewife, atlantic salmon, black crappie, bluegill, pickerel, largemouth bass, northern pike, pumpkinseed sunfish, rock bass, and yellow perch. There are state owned hard surface ramps in Cayuga–Seneca Canal, Lock #1 (Mud Lock), Long Point State Park, Cayuga Lake State Park, Deans Cove Boat Launch, Taughannock Falls State Park, and Allan H. Treman State Marine Park.
The major inflows to the lake are: Fall Creek, Cayuga Inlet, Salmon Creek, Taughannock Creek, and Six Mile Creek; while the lake outflows into the Seneca River and other tributaries. Ungaged tributaries that inflow to the lake include:
The lake is the subject of local folklore.
An Ithaca Journal article of January 5, 1897, reported that a sea serpent, nicknamed "Old Greeny," had been sighted in Cayuga Lake annually for 69 years. A sighting in that month described the animal, 200 feet (61 m) from shore, as "large and its body long," though a "tramp" suggested it was a muskrat. In 1929, two creatures, about 12 to 15 feet (3.7 to 4.6 m) in length, were reportedly spotted along the eastern shore of the lake. Further sightings were reported in 1974 and 1979.
Cornell's alma mater makes reference to its position "Far Above Cayuga's Waters", while that of Ithaca College references "Cayuga's shore".
A tradition at Wells College in Aurora holds that if the lake completely freezes over, classes are canceled (though for only one day). According to Wells College records, this most recently happened in 1979 and the record cold month of February 2015. However, other sources suggest that the only time the entire lake froze over solid end to end in the 20th century was in 1912, when even the deeper Seneca Lake last froze over completely.
Cayuga Lake, like nearby Seneca Lake, is also the site of a phenomenon known as the Guns of the Seneca, mysterious cannon-like booms heard in the surrounding area. Many of these booms may be attributable to bird-scarers, automated cannon-like devices used by farmers to scare birds away from the many vineyards, orchards and crops. There is, however, no proof of this.
Cayuga Lake is included in the American Viticultural Area with which it shares its name. Established in 1988, the AVA now boasts over a dozen wineries, four distilleries, a cidery, and a meadery. | [
{
"paragraph_id": 0,
"text": "Cayuga Lake (/kəˈjuːɡə/,/keɪˈjuːɡə/,/kaɪˈjuːɡə/) is the longest of central New York's glacial Finger Lakes, and is the second largest in surface area (marginally smaller than Seneca Lake) and second largest in volume. It is just under 39 miles (63 km) long. Its average width is 1.7 miles (2.8 km), and it is 3.5 mi wide (5.6 km) at its widest point, near Aurora. It is approximately 435 ft deep (133 m) at its deepest point, and has over 95 miles (153 km) of shoreline.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The lake is named after the indigenous Cayuga people.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The city of Ithaca, site of Ithaca College and Cornell University, is located at the southern end of Cayuga Lake.",
"title": "Location"
},
{
"paragraph_id": 3,
"text": "Villages and settlements along the east shore of Cayuga Lake include Myers, King Ferry, Aurora, Levanna, Union Springs, and Cayuga. Settlements along the west shore of the lake include Sheldrake, Poplar Beach, and Canoga.",
"title": "Location"
},
{
"paragraph_id": 4,
"text": "The lake has two small islands. One is near Union Springs, called Frontenac Island (northeast); this island is not inhabited. The other island, Canoga Island (northwest), is located near the town of Canoga. This island has several camps and is inhabited during the summer months. The only other island in any of the Finger Lakes is Skenoh Island in Canandaigua Lake.",
"title": "Location"
},
{
"paragraph_id": 5,
"text": "Cayuga Lake is located at 42°41′17″N 76°42′8″W / 42.68806°N 76.70222°W / 42.68806; -76.70222; 116.4 meters (382 ft) above sea level. Its depth, with steep east and west sides and shallow north and south ends, is typical of the Finger Lakes, as they were carved by glaciers during the last ice age.",
"title": "Location"
},
{
"paragraph_id": 6,
"text": "The water level is regulated by the Mud Lock at the north end of the lake. It is connected to Lake Ontario by the Erie Canal and Seneca Lake by the Seneca River. The lake is drawn down as winter approaches, to minimize ice damage and to maximize its capacity to store heavy spring runoff.",
"title": "Location"
},
{
"paragraph_id": 7,
"text": "The north end is dominated by shallow mudflats. An important stopover for migratory birds, the mudflats and marsh are the location of the Montezuma National Wildlife Refuge. The southern end is also shallow and often freezes during the winter.",
"title": "Location"
},
{
"paragraph_id": 8,
"text": "Cayuga Lake is very popular among recreational boaters. The Allan H. Treman State Marine Park, with a large state marina and boat launch, is located at the southern end of the lake in Ithaca. There are two yacht clubs on the western shore: Ithaca Yacht Club, a few miles north of Ithaca, and Red Jacket Yacht Club, just south of Canoga. There are several other marinas and boat launches, scattered along the lake shore.",
"title": "Location"
},
{
"paragraph_id": 9,
"text": "Cayuga Lake is the source of drinking water for several communities, including Lansing, near the southern end of the lake along the east side, which draws water through the Bolton Point Water System. There are also several lake source cooling systems that are in operation on the lake, whereby cooler water is pumped from the depths of the lake, warmed, and circulated in a closed system back to the surface. One of these systems, which is operated by Cornell University and began operation in 2000, was controversial during the planning and building stages, due to its potential for having a negative environmental impact. However, all of the environmental impact reports and scientific studies have shown that the Cornell lake source cooling system has not yet had, and will not likely have any measurably significant environmental impact. Furthermore, Cornell's system pumps significantly less warm water back into the lake than others further north, which have been operating for decades, including the coal-fired power plant on the eastern shore.",
"title": "Location"
},
{
"paragraph_id": 10,
"text": "The AES Coal Power plant was shut down in August 2019, and there are plans to convert it into a data center in the near future. The plant used to use Cayuga Lake as a cooling source. In the late 1960s, citizens successfully opposed the construction of an 830-MW nuclear power plant on the shore of Cayuga Lake.",
"title": "Location"
},
{
"paragraph_id": 11,
"text": "Rod Serling named his production company Cayuga Productions, during the years of his TV series, The Twilight Zone. Serling and his family had a summer home at Cayuga Lake.",
"title": "Location"
},
{
"paragraph_id": 12,
"text": "The fish population is managed and substantial sport fishing is practiced, with anglers targeting smelt, lake trout and smallmouth bass. Fish species present in the lake include lake trout, landlocked salmon, brown trout, rainbow trout, smallmouth bass, smelt, alewife, atlantic salmon, black crappie, bluegill, pickerel, largemouth bass, northern pike, pumpkinseed sunfish, rock bass, and yellow perch. There are state owned hard surface ramps in Cayuga–Seneca Canal, Lock #1 (Mud Lock), Long Point State Park, Cayuga Lake State Park, Deans Cove Boat Launch, Taughannock Falls State Park, and Allan H. Treman State Marine Park.",
"title": "Fishing"
},
{
"paragraph_id": 13,
"text": "The major inflows to the lake are: Fall Creek, Cayuga Inlet, Salmon Creek, Taughannock Creek, and Six Mile Creek; while the lake outflows into the Seneca River and other tributaries. Ungaged tributaries that inflow to the lake include:",
"title": "Tributaries"
},
{
"paragraph_id": 14,
"text": "The lake is the subject of local folklore.",
"title": "Folklore"
},
{
"paragraph_id": 15,
"text": "An Ithaca Journal article of January 5, 1897, reported that a sea serpent, nicknamed \"Old Greeny,\" had been sighted in Cayuga Lake annually for 69 years. A sighting in that month described the animal, 200 feet (61 m) from shore, as \"large and its body long,\" though a \"tramp\" suggested it was a muskrat. In 1929, two creatures, about 12 to 15 feet (3.7 to 4.6 m) in length, were reportedly spotted along the eastern shore of the lake. Further sightings were reported in 1974 and 1979.",
"title": "Folklore"
},
{
"paragraph_id": 16,
"text": "Cornell's alma mater makes reference to its position \"Far Above Cayuga's Waters\", while that of Ithaca College references \"Cayuga's shore\".",
"title": "Folklore"
},
{
"paragraph_id": 17,
"text": "A tradition at Wells College in Aurora holds that if the lake completely freezes over, classes are canceled (though for only one day). According to Wells College records, this most recently happened in 1979 and the record cold month of February 2015. However, other sources suggest that the only time the entire lake froze over solid end to end in the 20th century was in 1912, when even the deeper Seneca Lake last froze over completely.",
"title": "Folklore"
},
{
"paragraph_id": 18,
"text": "Cayuga Lake, like nearby Seneca Lake, is also the site of a phenomenon known as the Guns of the Seneca, mysterious cannon-like booms heard in the surrounding area. Many of these booms may be attributable to bird-scarers, automated cannon-like devices used by farmers to scare birds away from the many vineyards, orchards and crops. There is, however, no proof of this.",
"title": "Folklore"
},
{
"paragraph_id": 19,
"text": "Cayuga Lake is included in the American Viticultural Area with which it shares its name. Established in 1988, the AVA now boasts over a dozen wineries, four distilleries, a cidery, and a meadery.",
"title": "Wine"
}
] | Cayuga Lake (,,) is the longest of central New York's glacial Finger Lakes, and is the second largest in surface area and second largest in volume. It is just under 39 miles (63 km) long. Its average width is 1.7 miles (2.8 km), and it is 3.5 mi wide (5.6 km) at its widest point, near Aurora. It is approximately 435 ft deep (133 m) at its deepest point, and has over 95 miles (153 km) of shoreline. The lake is named after the indigenous Cayuga people. | 2001-09-09T22:11:45Z | 2023-11-04T15:32:39Z | [
"Template:Div col end",
"Template:Cite book",
"Template:Cite news",
"Template:Short description",
"Template:Infobox body of water",
"Template:Convert",
"Template:Citation needed",
"Template:Authority control",
"Template:Reflist",
"Template:Cite web",
"Template:Citation",
"Template:Webarchive",
"Template:Coord",
"Template:Div col",
"Template:See also",
"Template:Finger Lakes",
"Template:IPAc-en",
"Template:Portal",
"Template:Commons category"
] | https://en.wikipedia.org/wiki/Cayuga_Lake |
6,310 | Columbia University | Columbia University, officially Columbia University in the City of New York, is a private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhattan, it is the oldest institution of higher education in New York and the fifth-oldest in the United States.
Columbia was established as a colonial college by royal charter under George II of Great Britain. It was renamed Columbia College in 1784 following the American Revolution, and in 1787 was placed under a private board of trustees headed by former students Alexander Hamilton and John Jay. In 1896, the campus was moved to its current location in Morningside Heights and renamed Columbia University.
Columbia is organized into twenty schools, including four undergraduate schools and 16 graduate schools. The university's research efforts include the Lamont–Doherty Earth Observatory, the Goddard Institute for Space Studies, and accelerator laboratories with Big Tech firms such as Amazon and IBM. Columbia is a founding member of the Association of American Universities and was the first school in the United States to grant the MD degree. The university also annually administers the Pulitzer Prize. Its endowment stands at $13.3 billion as of 2022, which is among the largest of any academic institution.
Columbia scientists and scholars have played a pivotal role in scientific breakthroughs including brain-computer interface; the laser and maser; nuclear magnetic resonance; the first nuclear pile; the first nuclear fission reaction in the Americas; the first evidence for plate tectonics and continental drift; and much of the initial research and planning for the Manhattan Project during World War II.
As of December 2021, its alumni, faculty, and staff have included seven Founding Fathers of the United States; four U.S. presidents; 34 foreign heads of state; two secretaries-general of the United Nations; ten justices of the United States Supreme Court; 103 Nobel laureates; 125 National Academy of Sciences members; 53 living billionaires; 23 Olympic medalists; 33 Academy Award winners; and 125 Pulitzer Prize recipients.
Discussions regarding the founding of a college in the Province of New York began as early as 1704, at which time Colonel Lewis Morris wrote to the Society for the Propagation of the Gospel in Foreign Parts, the missionary arm of the Church of England, persuading the society that New York City was an ideal community in which to establish a college. However, it was not until the founding of the College of New Jersey (renamed Princeton) across the Hudson River in New Jersey that the City of New York seriously considered founding a college. In 1746, an act was passed by the general assembly of New York to raise funds for the foundation of a new college. In 1751, the assembly appointed a commission of ten New York residents, seven of whom were members of the Church of England, to direct the funds accrued by the state lottery towards the foundation of a college.
Classes were initially held in July 1754 and were presided over by the college's first president, Samuel Johnson. Johnson was the only instructor of the college's first class, which consisted of a mere eight students. Instruction was held in a new schoolhouse adjoining Trinity Church, located on what is now lower Broadway in Manhattan. The college was officially founded on October 31, 1754, as King's College by royal charter of George II, making it the oldest institution of higher learning in the State of New York and the fifth oldest in the United States.
In 1763, Johnson was succeeded in the presidency by Myles Cooper, a graduate of The Queen's College, Oxford, and an ardent Tory. In the charged political climate of the American Revolution, his chief opponent in discussions at the college was an undergraduate of the class of 1777, Alexander Hamilton. The Irish anatomist, Samuel Clossy, was appointed professor of natural philosophy in October 1765 and later the college's first professor of anatomy in 1767. The American Revolutionary War broke out in 1776, and was catastrophic for the operation of King's College, which suspended instruction for eight years beginning in 1776 with the arrival of the Continental Army. The suspension continued through the military occupation of New York City by British troops until their departure in 1783. The college's library was looted and its sole building requisitioned for use as a military hospital first by American and then British forces.
After the Revolutionary War, the college turned to the State of New York in order to restore its vitality, promising to make whatever changes to the school's charter the state might demand. The legislature agreed to assist the college, and on May 1, 1784, it passed "an Act for granting certain privileges to the College heretofore called King's College". The Act created a board of regents to oversee the resuscitation of King's College, and, in an effort to demonstrate its support for the new Republic, the legislature stipulated that "the College within the City of New York heretofore called King's College be forever hereafter called and known by the name of Columbia College", a reference to Columbia, an alternative name for America which in turn comes from the name of Christopher Columbus. The Regents finally became aware of the college's defective constitution in February 1787 and appointed a revision committee, which was headed by John Jay and Alexander Hamilton. In April of that same year, a new charter was adopted for the college granted the power to a separate board of 24 trustees.
On May 21, 1787, William Samuel Johnson, the son of Samuel Johnson, was unanimously elected president of Columbia College. Prior to serving at the university, Johnson had participated in the First Continental Congress and been chosen as a delegate to the Constitutional Convention. For a period in the 1790s, with New York City as the federal and state capital and the country under successive Federalist governments, a revived Columbia thrived under the auspices of Federalists such as Hamilton and Jay. President George Washington and Vice President John Adams, in addition to both houses of Congress attended the college's commencement on May 6, 1789, as a tribute of honor to the many alumni of the school who had been involved in the American Revolution.
In November 1813, the college agreed to incorporate its medical school with The College of Physicians and Surgeons, a new school created by the Regents of New York, forming Columbia University College of Physicians and Surgeons. The college's enrollment, structure, and academics stagnated for the majority of the 19th century, with many of the college presidents doing little to change the way that the college functioned. In 1857, the college moved from the King's College campus at Park Place to a primarily Gothic Revival campus on 49th Street and Madison Avenue, where it remained for the next forty years.
During the last half of the 19th century, under the leadership of President F.A.P. Barnard, the president that Barnard College is named after, the institution rapidly assumed the shape of a modern university. Barnard College was created in 1889 as a response to the university's refusal to accept women. By this time, the college's investments in New York real estate became a primary source of steady income for the school, mainly owing to the city's expanding population.
In 1896, university president Seth Low moved the campus from 49th Street to its present location, a more spacious campus in the developing neighborhood of Morningside Heights. Under the leadership of Low's successor, Nicholas Murray Butler, who served for over four decades, Columbia rapidly became the nation's major institution for research, setting the multiversity model that later universities would adopt. Prior to becoming the president of Columbia University, Butler founded Teachers College, as a school to prepare home economists and manual art teachers for the children of the poor, with philanthropist Grace Hoadley Dodge. Teachers College is currently affiliated as the university's Graduate School of Education.
Research into the atom by faculty members John R. Dunning, I. I. Rabi, Enrico Fermi and Polykarp Kusch placed Columbia's physics department in the international spotlight in the 1940s after the first nuclear pile was built to start what became the Manhattan Project. In 1928, Seth Low Junior College was established by Columbia University in order to mitigate the number of Jewish applicants to Columbia College. The college was closed in 1936 due to the adverse effects of the Great Depression and its students were subsequently taught at Morningside Heights, although they did not belong to any college but to the university at large. There was an evening school called University Extension, which taught night classes, for a fee, to anyone willing to attend.
In 1947, the program was reorganized as an undergraduate college and designated the School of General Studies in response to the return of GIs after World War II. In 1995, the School of General Studies was again reorganized as a full-fledged liberal arts college for non-traditional students (those who have had an academic break of one year or more, or are pursuing dual-degrees) and was fully integrated into Columbia's traditional undergraduate curriculum. The same year, the Division of Special Programs, later called the School of Continuing Education and now the School of Professional Studies, was established to reprise the former role of University Extension. While the School of Professional Studies only offered non-degree programs for lifelong learners and high school students in its earliest stages, it now offers degree programs in a diverse range of professional and inter-disciplinary fields.
In the aftermath of World War II, the discipline of international relations became a major scholarly focus of the university, and in response, the School of International and Public Affairs was founded in 1946, drawing upon the resources of the faculties of political science, economics, and history. The Columbia University Bicentennial was celebrated in 1954.
During the 1960s Columbia experienced large-scale student activism, which reached a climax in the spring of 1968 when hundreds of students occupied buildings on campus. The incident forced the resignation of Columbia's president, Grayson Kirk, and the establishment of the University Senate.
Though several schools within the university had admitted women for years, Columbia College first admitted women in the fall of 1983, after a decade of failed negotiations with Barnard College, the all-female institution affiliated with the university, to merge the two schools. Barnard College still remains affiliated with Columbia, and all Barnard graduates are issued diplomas signed by the presidents of Columbia University and Barnard College.
During the late 20th century, the university underwent significant academic, structural, and administrative changes as it developed into a major research university. For much of the 19th century, the university consisted of decentralized and separate faculties specializing in Political Science, Philosophy, and Pure Science. In 1979, these faculties were merged into the Graduate School of Arts and Sciences.
In 1991, the faculties of Columbia College, the School of General Studies, the Graduate School of Arts and Sciences, the School of the Arts, and the School of Professional Studies were merged into the Faculty of Arts and Sciences, leading to the academic integration and centralized governance of these schools.
In 2010, the School of International and Public Affairs, which was previously a part of the Faculty of Arts and Sciences, became an independent faculty.
The majority of Columbia's graduate and undergraduate studies are conducted in the Upper Manhattan neighborhood of Morningside Heights on Seth Low's late-19th century vision of a university campus where all disciplines could be taught at one location. The campus was designed along Beaux-Arts planning principles by the architects McKim, Mead & White. Columbia's main campus occupies more than six city blocks, or 32 acres (13 ha), in Morningside Heights, New York City, a neighborhood that contains a number of academic institutions. The university owns over 7,800 apartments in Morningside Heights, housing faculty, graduate students, and staff. Almost two dozen undergraduate dormitories (purpose-built or converted) are located on campus or in Morningside Heights. Columbia University has an extensive tunnel system, more than a century old, with the oldest portions predating the present campus. Some of these remain accessible to the public, while others have been cordoned off.
The Nicholas Murray Butler Library, known simply as Butler Library, is the largest single library in the Columbia University Library System, and is one of the largest buildings on the campus. Proposed as "South Hall" by the university's former president Nicholas Murray Butler as expansion plans for Low Memorial Library stalled, the new library was funded by Edward Harkness, benefactor of Yale's residential college system, and designed by his favorite architect, James Gamble Rogers. It was completed in 1934 and renamed for Butler in 1946. The library design is neo-classical in style. Its facade features a row of columns in the Ionic order above which are inscribed the names of great writers, philosophers, and thinkers, most of whom are read by students engaged in the Core Curriculum of Columbia College. As of 2020, Columbia's library system includes over 15.0 million volumes, making it the eighth largest library system and fifth largest collegiate library system in the United States.
Several buildings on the Morningside Heights campus are listed on the National Register of Historic Places. Low Memorial Library, a National Historic Landmark and the centerpiece of the campus, is listed for its architectural significance. Philosophy Hall is listed as the site of the invention of FM radio. Also listed is Pupin Hall, another National Historic Landmark, which houses the physics and astronomy departments. Here the first experiments on the fission of uranium were conducted by Enrico Fermi. The uranium atom was split there ten days after the world's first atom-splitting in Copenhagen, Denmark. Other buildings listed include Casa Italiana, the Delta Psi, Alpha Chapter building of St. Anthony Hall, Earl Hall, and the buildings of the affiliated Union Theological Seminary.
A statue by sculptor Daniel Chester French called Alma Mater is centered on the front steps of Low Memorial Library. McKim, Mead & White invited French to build the sculpture in order to harmonize with the larger composition of the court and library in the center of the campus. Draped in an academic gown, the female figure of Alma Mater wears a crown of laurels and sits on a throne. The scroll-like arms of the throne end in lamps, representing sapientia and doctrina. A book signifying knowledge, balances on her lap, and an owl, the attribute of wisdom, is hidden in the folds of her gown. Her right hand holds a scepter composed of four sprays of wheat, terminating with a crown of King's College which refers to Columbia's origin as a royal charter institution in 1754. A local actress named Mary Lawton was said to have posed for parts of the sculpture. The statue was dedicated on September 23, 1903, as a gift of Mr. & Mrs. Robert Goelet, and was originally covered in golden leaf. During the Columbia University protests of 1968 a bomb damaged the sculpture, but it has since been repaired. The small hidden owl on the sculpture is also the subject of many Columbia legends, the main legend being that the first student in the freshmen class to find the hidden owl on the statue will be valedictorian, and that any subsequent Columbia male who finds it will marry a Barnard student, given that Barnard is a women's college.
"The Steps", alternatively known as "Low Steps" or the "Urban Beach", are a popular meeting area for Columbia students. The term refers to the long series of granite steps leading from the lower part of campus (South Field) to its upper terrace. With a design inspired by the City Beautiful movement, the steps of Low Library provides Columbia University and Barnard College students, faculty, and staff with a comfortable outdoor platform and space for informal gatherings, events, and ceremonies. McKim's classical facade epitomizes late 19th-century new-classical designs, with its columns and portico marking the entrance to an important structure.
In April 2007, the university purchased more than two-thirds of a 17 acres (6.9 ha) site for a new campus in Manhattanville, an industrial neighborhood to the north of the Morningside Heights campus. Stretching from 125th Street to 133rd Street, Columbia Manhattanville houses buildings for Columbia's Business School, School of International and Public Affairs, Columbia School of the Arts, and the Jerome L. Greene Center for Mind, Brain, and Behavior, where research will occur on neurodegenerative diseases such as Parkinson's and Alzheimer's. The $7 billion expansion plan included demolishing all buildings, except three that are historically significant (the Studebaker Building, Prentis Hall, and the Nash Building), eliminating the existing light industry and storage warehouses, and relocating tenants in 132 apartments. Replacing these buildings created 6.8 million square feet (630,000 m) of space for the university. Community activist groups in West Harlem fought the expansion for reasons ranging from property protection and fair exchange for land, to residents' rights. Subsequent public hearings drew neighborhood opposition. As of December 2008, the State of New York's Empire State Development Corporation approved use of eminent domain, which, through declaration of Manhattanville's "blighted" status, gives governmental bodies the right to appropriate private property for public use. On May 20, 2009, the New York State Public Authorities Control Board approved the Manhanttanville expansion plan.
NewYork-Presbyterian Hospital is affiliated with the medical schools of both Columbia University and Cornell University. According to U.S. News & World Report's "2020–21 Best Hospitals Honor Roll and Medical Specialties Rankings", it is ranked fourth overall and second among university hospitals. Columbia's medical school has a strategic partnership with New York State Psychiatric Institute, and is affiliated with 19 other hospitals in the U.S. and four hospitals in other countries. Health-related schools are located at the Columbia University Medical Center, a 20-acre (8.1 ha) campus located in the neighborhood of Washington Heights, fifty blocks uptown. Other teaching hospitals affiliated with Columbia through the NewYork-Presbyterian network include the Payne Whitney Clinic in Manhattan, and the Payne Whitney Westchester, a psychiatric institute located in White Plains, New York. On the northern tip of Manhattan island (in the neighborhood of Inwood), Columbia owns the 26-acre (11 ha) Baker Field, which includes the Lawrence A. Wien Stadium as well as facilities for field sports, outdoor track, and tennis. There is a third campus on the west bank of the Hudson River, the 157-acre (64 ha) Lamont–Doherty Earth Observatory and Earth Institute in Palisades, New York. A fourth is the 60-acre (24 ha) Nevis Laboratories in Irvington, New York, for the study of particle and motion physics. A satellite site in Paris holds classes at Reid Hall.
In 2006, the university established the Office of Environmental Stewardship to initiate, coordinate and implement programs to reduce the university's environmental footprint. The U.S. Green Building Council selected the university's Manhattanville plan for the Leadership in Energy and Environmental Design (LEED) Neighborhood Design pilot program. The plan commits to incorporating smart growth, new urbanism and "green" building design principles. Columbia is one of the 2030 Challenge Partners, a group of nine universities in the city of New York that have pledged to reduce their greenhouse emissions by 30% within the next ten years. Columbia University adopts LEED standards for all new construction and major renovations. The university requires a minimum of Silver, but through its design and review process seeks to achieve higher levels. This is especially challenging for lab and research buildings with their intensive energy use; however, the university also uses lab design guidelines that seek to maximize energy efficiency while protecting the safety of researchers.
Every Thursday and Sunday of the month, Columbia hosts a greenmarket where local farmers can sell their produce to residents of the city. In addition, from April to November Hodgson's farm, a local New York gardening center, joins the market bringing a large selection of plants and blooming flowers. The market is one of the many operated at different points throughout the city by the non-profit group GrowNYC. Dining services at Columbia spends 36 percent of its food budget on local products, in addition to serving sustainably harvested seafood and fair trade coffee on campus. Columbia has been rated "B+" by the 2011 College Sustainability Report Card for its environmental and sustainability initiatives.
According to the A. W. Kuchler U.S. potential natural vegetation types, Columbia University would have a dominant vegetation type of Appalachian Oak (104) with a dominant vegetation form of Eastern Hardwood Forest (25).
Columbia Transportation is the bus service of the university, operated by Academy Bus Lines. The buses are open to all Columbia faculty, students, Dodge Fitness Center members, and anyone else who holds a Columbia ID card. In addition, all TSC students can ride the buses.
In the New York City Subway, the train serves the university at 116th Street-Columbia University. The M4, M104 and M60 buses stop on Broadway while the M11 stops on Amsterdam Avenue.
Columbia University received 60,551 applications for the class of 2025 (entering 2021) and a total of around 2,218 were admitted to the two schools for an overall acceptance rate of 3.66%. Columbia is a racially diverse school, with approximately 52% of all students identifying themselves as persons of color. Additionally, 50% of all undergraduates received grants from Columbia. The average grant size awarded to these students is $46,516. In 2015–2016, annual undergraduate tuition at Columbia was $50,526 with a total cost of attendance of $65,860 (including room and board). The college is need-blind for domestic applicants.
Annual gifts, fund-raising, and an increase in spending from the university's endowment have allowed Columbia to extend generous financial aid packages to qualifying students. On April 11, 2007, Columbia University announced a $400 million donation from media billionaire alumnus John Kluge to be used exclusively for undergraduate financial aid. The donation is among the largest single gifts to higher education. As of 2008, undergraduates from families with incomes as high as $60,000 a year will have the projected cost of attending the university, including room, board, and academic fees, fully paid for by the university. That same year, the university ended loans for incoming and then-current students who were on financial aid, replacing loans that were traditionally part of aid packages with grants from the university. However, this does not apply to international students, transfer students, visiting students, or students in the School of General Studies. In the fall of 2010, admission to Columbia's undergraduate colleges Columbia College and the Fu Foundation School of Engineering and Applied Science (also known as SEAS or Columbia Engineering) began accepting the Common Application. The policy change made Columbia one of the last major academic institutions and the last Ivy League university to switch to the Common Application.
Scholarships are also given to undergraduate students by the admissions committee. Designations include John W. Kluge Scholars, John Jay Scholars, C. Prescott Davis Scholars, Global Scholars, Egleston Scholars, and Science Research Fellows. Named scholars are selected by the admission committee from first-year applicants. According to Columbia, the first four designated scholars "distinguish themselves for their remarkable academic and personal achievements, dynamism, intellectual curiosity, the originality and independence of their thinking, and the diversity that stems from their different cultures and their varied educational experiences".
In 1919, Columbia established a student application process characterized by The New York Times as "the first modern college application". The application required a photograph of the applicant, the maiden name of the applicant's mother, and the applicant's religious background.
Columbia University is an independent, privately supported, nonsectarian institution of higher education. Its official corporate name is "The Trustees of Columbia University in the City of New York". The university's first charter was granted in 1754 by King George II; however, its modern charter was first enacted in 1787 and last amended in 1810 by the New York State Legislature. The university is governed by 24 trustees, customarily including the president, who serves ex officio. The trustees themselves are responsible for choosing their successors. Six of the 24 are nominated from a pool of candidates recommended by the Columbia Alumni Association. Another six are nominated by the board in consultation with the executive committee of the University Senate. The remaining 12, including the president, are nominated by the trustees themselves through their internal processes. The term of office for trustees is six years. Generally, they serve for no more than two consecutive terms. The trustees appoint the president and other senior administrative officers of the university, and review and confirm faculty appointments as required. They determine the university's financial and investment policies, authorize the budget, supervise the endowment, direct the management of the university's real estate and other assets, and otherwise oversee the administration and management of the university.
The University Senate was established by the trustees after a university-wide referendum in 1969. It succeeded to the powers of the University Council, which was created in 1890 as a body of faculty, deans, and other administrators to regulate inter-Faculty affairs and consider issues of university-wide concern. The University Senate is a unicameral body consisting of 107 members drawn from all constituencies of the university. These include the president of the university, the provost, the deans of Columbia College and the Graduate School of Arts and Sciences, all of whom serve ex officio, and five additional representatives, appointed by the president, from the university's administration. The president serves as the Senate's presiding officer. The Senate is charged with reviewing the educational policies, physical development, budget, and external relations of the university. It oversees the welfare and academic freedom of the faculty and the welfare of students.
The president of Columbia University, who is selected by the trustees in consultation with the executive committee of the University Senate and who serves at the trustees' pleasure, is the chief executive officer of the university. Assisting the president in administering the university are the provost, the senior executive vice president, the executive vice president for health and biomedical sciences, several other vice presidents, the general counsel, the secretary of the university, and the deans of the faculties, all of whom are appointed by the trustees on the nomination of the president and serve at their pleasure. Minouche Shafik became the 20th president of Columbia University on July 1, 2023.
Columbia has four official undergraduate colleges: Columbia College, the liberal arts college offering the Bachelor of Arts degree; the Fu Foundation School of Engineering and Applied Science (also known as SEAS or Columbia Engineering), the engineering and applied science school offering the Bachelor of Science degree; the School of General Studies, the liberal arts college offering the Bachelor of Arts degree to non-traditional students undertaking full- or part-time study; and Barnard College. Barnard College is a women's liberal arts college and an academic affiliate in which students receive a Bachelor of Arts degree from Columbia University. Their degrees are signed by the presidents of Columbia University and Barnard College. Barnard students are also eligible to cross-register classes that are available through the Barnard Catalogue and alumnae can join the Columbia Alumni Association.
Joint degree programs are available through Union Theological Seminary, the Jewish Theological Seminary of America, and the Juilliard School. Teachers College and Barnard College are official faculties of the university; both colleges' presidents are deans under the university governance structure. The Columbia University Senate includes faculty and student representatives from Teachers College and Barnard College who serve two-year terms; all senators are accorded full voting privileges regarding matters impacting the entire university. Teachers College is an affiliated, financially independent graduate school with their own board of trustees. Pursuant to an affiliation agreement, Columbia is given the authority to confer "degrees and diplomas" to the graduates of Teachers College. The degrees are signed by presidents of Teachers College and Columbia University in a manner analogous to the university's other graduate schools. Columbia's General Studies school also has joint undergraduate programs available through University College London, Sciences Po, City University of Hong Kong, Trinity College Dublin, and the Juilliard School.
The university also has several Columbia Global Centers, in Amman, Beijing, Istanbul, Mumbai, Nairobi, Paris, Rio de Janeiro, Santiago, and Tunis.
Columbia students can study abroad for a semester or a year at partner institutions such as Sciences Po, École des hautes études en sciences sociales (EHESS), École normale supérieure (ENS), Panthéon-Sorbonne University, King's College London, London School of Economics, University College London and the University of Warwick. Select students can study at either the University of Oxford or the University of Cambridge for a year if approved by both Columbia and either Oxford or Cambridge. Columbia also has a dual MA program with the Aga Khan University in London.
Columbia University is ranked 12th in the United States and seventh globally for 2023–2024 by U.S. News & World Report. QS University Rankings listed Columbia as fifth in the United States. Ranked 15th among U.S. colleges for 2020 by The Wall Street Journal and Times Higher Education, in recent years it has been ranked as high as second. Individual colleges and schools were also nationally ranked by U.S. News & World Report for its 2021 edition. Columbia Law School was ranked fourth, the Mailman School of Public Health fourth, the School of Social Work tied for third, Columbia Business School eighth, the College of Physicians and Surgeons tied for sixth for research (and tied for 31st for primary care), the School of Nursing tied for 11th in the master's program and tied for first in the doctorate nursing program, and the Fu Foundation School of Engineering and Applied Science (graduate) was ranked tied for 14th.
In 2021, Columbia was ranked seventh in the world (sixth in the United States) by Academic Ranking of World Universities, sixth in the world by U.S. News & World Report, 19th in the world by QS World University Rankings, and 11th globally by Times Higher Education World University Rankings. It was ranked in the first tier of American research universities, along with Harvard, MIT, and Stanford, in the 2019 report from the Center for Measuring University Performance. Columbia's Graduate School of Architecture, Planning and Preservation was ranked the second most admired graduate program by Architectural Record in 2020.
In 2011, the Mines ParisTech: Professional Ranking of World Universities ranked Columbia third best university for forming CEOs in the US and 12th worldwide.
In 2022, Columbia's reporting of metrics used for university ranking was criticized by Professor of Mathematics Michael Thaddeus, who argued key data supporting the ranking was "inaccurate, dubious or highly misleading." Subsequently, U.S. News & World Report "unranked" Columbia from its 2022 list of Best Colleges saying that it could not verify the data submitted by the university. In June 2023, Columbia University announced their undergraduate schools would no longer participate in U.S. News & World Report's rankings, following the lead of its law, medical and nursing schools. A press release cited concerns that such rankings unduly influence applicants and "distill a university's profile into a composite of data categories."
Columbia is classified among "R1: Doctoral Universities – Very high research activity". Columbia was the first North American site where the uranium atom was split. The College of Physicians and Surgeons played a central role in developing the modern understanding of neuroscience with the publication of Principles of Neural Science, described by historian of science Katja Huenther as the "neuroscience 'bible' ". The book was written by a team of Columbia researchers that included Nobel Prize winner Eric Kandel, James H. Schwartz, and Thomas Jessell. Columbia was the birthplace of FM radio and the laser. The first brain-computer interface capable of translating brain signals into speech was developed by neuroengineers at Columbia. The MPEG-2 algorithm of transmitting high quality audio and video over limited bandwidth was developed by Dimitris Anastassiou, a Columbia professor of electrical engineering. Biologist Martin Chalfie was the first to introduce the use of Green Fluorescent Protein (GFP) in labeling cells in intact organisms. Other inventions and products related to Columbia include Sequential Lateral Solidification (SLS) technology for making LCDs, System Management Arts (SMARTS), Session Initiation Protocol (SIP) (which is used for audio, video, chat, instant messaging and whiteboarding), pharmacopeia, Macromodel (software for computational chemistry), a new and better recipe for glass concrete, Blue LEDs, and Beamprop (used in photonics).
Columbia scientists have been credited with about 175 new inventions in the health sciences each year. More than 30 pharmaceutical products based on discoveries and inventions made at Columbia reached the market. These include Remicade (for arthritis), Reopro (for blood clot complications), Xalatan (for glaucoma), Benefix, Latanoprost (a glaucoma treatment), shoulder prosthesis, homocysteine (testing for cardiovascular disease), and Zolinza (for cancer therapy). Columbia Technology Ventures (formerly Science and Technology Ventures), as of 2008, manages some 600 patents and more than 250 active license agreements. Patent-related deals earned Columbia more than $230 million in the 2006 fiscal year, according to the university, more than any university in the world. Columbia owns many unique research facilities, such as the Columbia Institute for Tele-Information dedicated to telecommunications and the Goddard Institute for Space Studies, which is an astronomical observatory affiliated with NASA.
Columbia is a long-standing participant of the United States Department of Veterans Affairs Yellow Ribbon Program, allowing eligible veterans to pursue a Columbia undergraduate degree regardless of socioeconomic status for over 70 years. As a part of the Eisenhower Leader Development Program (ELDP) in partnership with the United States Military Academy at West Point, Columbia is the only school in the Ivy League to offer a graduate degree program in organizational psychology to aid military officers in tactical decision making and strategic management.
Several prestigious awards are administered by Columbia University, most notably the Pulitzer Prize and the Bancroft Prize in history. Other prizes, which are awarded by the Graduate School of Journalism, include the Alfred I. duPont–Columbia University Award, the National Magazine Awards, the Maria Moors Cabot Prizes, the John Chancellor Award, and the Lukas Prizes, which include the J. Anthony Lukas Book Prize and Mark Lynton History Prize. The university also administers the Louisa Gross Horwitz Prize, which is considered an important precursor to the Nobel Prize, 51 of its 101 recipients having gone on to win either a Nobel Prize in Physiology or Medicine or Nobel Prize in Chemistry as of October 2018; the W. Alden Spencer Award; the Vetlesen Prize, which is known as the Nobel Prize of geology; the Japan-U.S. Friendship Commission Prize for the Translation of Japanese Literature, the oldest such award; the Edwin Howard Armstrong award; the Calderone Prize in public health; and the Ditson Conductor's Award.
In 2020, Columbia University's student population was 31,455 (8,842 students in undergraduate programs and 22,613 in postgraduate programs), with 45% of the student population identifying themselves as a minority. Twenty-six percent of students at Columbia have family incomes below $60,000. 16% of students at Columbia receive Federal Pell Grants, which mostly go to students whose family incomes are below $40,000. Seventeen percent of students are the first member of their family to attend a four-year college.
On-campus housing is guaranteed for all four years as an undergraduate. Columbia College and the Fu Foundation School of Engineering and Applied Science (also known as SEAS or Columbia Engineering) share housing in the on-campus residence halls. First-year students usually live in one of the large residence halls situated around South Lawn: Carman Hall, Furnald Hall, Hartley Hall, John Jay Hall, or Wallach Hall (originally Livingston Hall). Upperclassmen participate in a room selection process, wherein students can pick to live in a mix of either corridor- or apartment-style housing with their friends. The Columbia University School of General Studies, Barnard College and graduate schools have their own apartment-style housing in the surrounding neighborhood.
Columbia University is home to many fraternities, sororities, and co-educational Greek organizations. Approximately 10–15% of undergraduate students are associated with Greek life. Many Barnard women also join Columbia sororities. There has been a Greek presence on campus since the establishment in 1836 of the Delta chapter of Alpha Delta Phi. The InterGreek Council is the self-governing student organization that provides guidelines and support to its member organizations within each of the three councils at Columbia, the Interfraternity Council, Panhellenic Council, and Multicultural Greek Council. The three council presidents bring their affiliated chapters together once a month to meet as one Greek community. The InterGreek Council meetings provide opportunity for member organizations to learn from each other, work together and advocate for community needs.
The Columbia Daily Spectator is the nation's second-oldest continuously operating daily student newspaper. The Blue and White is a monthly literary magazine established in 1890 that discusses campus life and local politics. Bwog, originally an offshoot of The Blue and White but now fully independent, is an online campus news and entertainment source. The Morningside Post is a student-run multimedia news publication.
Political publications include The Current, a journal of politics, culture and Jewish Affairs; the Columbia Political Review, the multi-partisan political magazine of the Columbia Political Union; and AdHoc, which denotes itself as the "progressive" campus magazine and deals largely with local political issues and arts events.
Columbia Magazine is the alumni magazine of Columbia, serving all 340,000+ of the university's alumni. Arts and literary publications include The Columbia Review, the nation's oldest college literary magazine; Surgam, the literary magazine of The Philolexian Society; Quarto, Columbia University's official undergraduate literary magazine; 4x4, a student-run alternative to Quarto; Columbia, a nationally regarded literary journal; the Columbia Journal of Literary Criticism; and The Mobius Strip, an online arts and literary magazine. Inside New York is an annual guidebook to New York City, written, edited, and published by Columbia undergraduates. Through a distribution agreement with Columbia University Press, the book is sold at major retailers and independent bookstores.
Columbia is home to numerous undergraduate academic publications. The Columbia Undergraduate Science Journal prints original science research in its two annual publications. The Journal of Politics & Society is a journal of undergraduate research in the social sciences; Publius is an undergraduate journal of politics established in 2008 and published biannually; the Columbia East Asia Review allows undergraduates throughout the world to publish original work on China, Japan, Korea, Tibet, and Vietnam and is supported by the Weatherhead East Asian Institute; The Birch is an undergraduate journal of Eastern European and Eurasian culture that is the first national student-run journal of its kind; the Columbia Economics Review is the undergraduate economic journal on research and policy supported by the Columbia Economics Department; and the Columbia Science Review is a science magazine that prints general interest articles and faculty profiles.
Humor publications on Columbia's campus include The Fed, a triweekly satire and investigative newspaper, and the Jester of Columbia. Other publications include The Columbian, the undergraduate colleges' annually published yearbook; the Gadfly, a biannual journal of popular philosophy produced by undergraduates; and Rhapsody in Blue, an undergraduate urban studies magazine. Professional journals published by academic departments at Columbia University include Current Musicology and The Journal of Philosophy. During the spring semester, graduate students in the Journalism School publish The Bronx Beat, a bi-weekly newspaper covering the South Bronx.
Founded in 1961 under the auspices of Columbia University's Graduate School of Journalism, the Columbia Journalism Review (CJR) examines day-to-day press performance as well as the forces that affect that performance. The magazine is published six times a year.
Former publications include the Columbia University Forum, a review of literature and cultural affairs distributed for free to alumni.
Columbia is home to two pioneers in undergraduate campus radio broadcasting, WKCR-FM and CTV. Many undergraduates are also involved with Barnard's radio station, WBAR. WKCR, the student run radio station that broadcasts to the Tri-state area, claims to be the oldest FM radio station in the world, owing to the university's affiliation with Major Edwin Armstrong. The station went operational on July 18, 1939, from a 400-foot antenna tower in Alpine, New Jersey, broadcasting the first FM transmission in the world. Initially, WKCR was not a radio station, but an organization concerned with the technology of radio communications. As membership grew, however, the nascent club turned its efforts to broadcasting. Armstrong helped the students in their early efforts, donating a microphone and turntables when they designed their first makeshift studio in a dorm room. The station has its studios on the second floor of Alfred Lerner Hall on the Morningside campus with its main transmitter tower at 4 Times Square in Midtown Manhattan. Columbia Television (CTV) is the nation's second oldest student television station and the home of CTV News, a weekly live news program produced by undergraduate students.
The Philolexian Society is a literary and debating club founded in 1802, making it the oldest student group at Columbia, as well as the third oldest collegiate literary society in the country. The society annually administers the Joyce Kilmer Memorial Bad Poetry Contest. The Columbia Parliamentary Debate Team competes in tournaments around the country as part of the American Parliamentary Debate Association, and hosts both high school and college tournaments on Columbia's campus, as well as public debates on issues affecting the university.
The Columbia International Relations Council and Association (CIRCA), oversees Columbia's Model United Nations activities. CIRCA hosts college and high school Model UN conferences, hosts speakers influential in international politics to speak on campus, and trains students from underprivileged schools in New York in Model UN.
Columbia is a top supplier of young engineering entrepreneurs for New York City. Over the past 20 years, graduates of Columbia established over 100 technology companies.
The Columbia University Organization of Rising Entrepreneurs (CORE) was founded in 1999. The student-run group aims to foster entrepreneurship on campus. Each year CORE hosts dozens of events, including talks, #StartupColumbia, a conference and venture competition for $250,000, and Ignite@CU, a weekend for undergrads interested in design, engineering, and entrepreneurship. Notable speakers include Peter Thiel, Jack Dorsey, Alexis Ohanian, Drew Houston, and Mark Cuban. As of 2006, CORE had awarded graduate and undergraduate students over $100,000 in seed capital.
CampusNetwork, an on-campus social networking site called Campus Network that preceded Facebook, was created and popularized by Columbia engineering student Adam Goldberg in 2003. Mark Zuckerberg later asked Goldberg to join him in Palo Alto to work on Facebook, but Goldberg declined the offer. The Fu Foundation School of Engineering and Applied Science offers a minor in Technical Entrepreneurship through its Center for Technology, Innovation, and Community Engagement. SEAS' entrepreneurship activities focus on community building initiatives in New York and worldwide, made possible through partners such as Microsoft Corporation.
On June 14, 2010, Mayor Michael R. Bloomberg launched the NYC Media Lab to promote innovations in New York's media industry. Situated at the New York University Tandon School of Engineering, the lab is a consortium of Columbia University, New York University, and New York City Economic Development Corporation acting to connect companies with universities in new technology research. The Lab is modeled after similar ones at MIT and Stanford, and was established with a $250,000 grant from the New York City Economic Development Corporation.
A member institution of the National Collegiate Athletic Association (NCAA) in Division I FCS, Columbia fields varsity teams in 29 sports and is a member of the Ivy League. The football Lions play home games at the 17,000-seat Robert K. Kraft Field at Lawrence A. Wien Stadium. The Baker Athletics Complex also includes facilities for baseball, softball, soccer, lacrosse, field hockey, tennis, track, and rowing, as well as the new Campbell Sports Center, which opened in January 2013. The basketball, fencing, swimming & diving, volleyball, and wrestling programs are based at the Dodge Physical Fitness Center on the main campus.
Former students include Baseball Hall of Famers Lou Gehrig and Eddie Collins, football Hall of Famer Sid Luckman, Marcellus Wiley, and world champion women's weightlifter Karyn Marshall. On May 17, 1939, fledgling NBC broadcast a doubleheader between the Columbia Lions and the Princeton Tigers at Columbia's Baker Field, making it the first televised regular athletic event in history.
Columbia University athletics has a long history, with many accomplishments in athletic fields. In 1870, Columbia played against Rutgers University in the second intercollegiate rugby football game in the history of the sport. Eight years later, Columbia crew won the famed Henley Royal Regatta in the first-ever defeat for an English crew rowing in English waters. In 1900, Olympian and Columbia College student Maxie Long set the first official world record in the 400 meters with a time of 47.8 seconds. In 1983, Columbia men's soccer went 18–0 and was ranked first in the nation, but lost to Indiana 1–0 in double overtime in the NCAA championship game; nevertheless, the team went further toward the NCAA title than any Ivy League soccer team in history. The football program unfortunately is best known for its record of futility set during the 1980s: between 1983 and 1988, the team lost 44 games in a row, which is still the record for the NCAA Football Championship Subdivision. The streak was broken on October 8, 1988, with a 16–13 victory over arch-rival Princeton University. That was the Lions' first victory at Wien Stadium, which had been opened during the losing streak and was already four years old. A new tradition has developed with the Liberty Cup. The Liberty Cup is awarded annually to the winner of the football game between Fordham and Columbia Universities, two of the only three NCAA Division I football teams in New York City.
Established in 2003 by university president Lee C. Bollinger, the World Leaders Forum at Columbia University provides the opportunity for undergraduate and graduate students alike to listen to world leaders in government, religion, industry, finance, and academia. The World Leaders Forum is a year-around event series that strives to provide a platform for uninhibited speech among nations and cultures, while educating students about problems and progress around the globe.
Past forum speakers include former president of the United States Bill Clinton, the prime minister of India Atal Bihari Vajpayee, former president of Ghana John Agyekum Kufuor, president of Afghanistan Hamid Karzai, prime minister of Russia Vladimir Putin, president of the Republic of Mozambique Joaquim Alberto Chissano, president of the Republic of Bolivia Carlos Diego Mesa Gisbert, president of the Republic of Romania Ion Iliescu, president of the Republic of Latvia Vaira Vīķe-Freiberga, the first female president of Finland Tarja Halonen, President Yudhoyono of Indonesia, President Pervez Musharraf of the Islamic Republic of Pakistan, Iraq President Jalal Talabani, the 14th Dalai Lama, president of the Islamic Republic of Iran Mahmoud Ahmadinejad, financier George Soros, Mayor of New York City Michael R. Bloomberg, President Václav Klaus of the Czech Republic, President Cristina Fernández de Kirchner of Argentina, former Secretary-General of the United Nations Kofi Annan, and Al Gore.
The Columbia University Orchestra was founded by composer Edward MacDowell in 1896, and is the oldest continually operating university orchestra in the United States. Undergraduate student composers at Columbia may choose to become involved with Columbia New Music, which sponsors concerts of music written by undergraduate students from all of Columbia's schools. The Notes and Keys, the oldest a cappella group at Columbia, was founded in 1909. There are a number of performing arts groups at Columbia dedicated to producing student theater, including the Columbia Players, King's Crown Shakespeare Troupe (KCST), Columbia Musical Theater Society (CMTS), NOMADS (New and Original Material Authored and Directed by Students), LateNite Theatre, Columbia University Performing Arts League (CUPAL), Black Theatre Ensemble (BTE), sketch comedy group Chowdah, and improvisational troupes Alfred and Fruit Paunch.
The Columbia Queer Alliance is the central Columbia student organization that represents the bisexual, lesbian, gay, transgender, and questioning student population. It is the oldest gay student organization in the world, founded as the Student Homophile League in 1967 by students including lifelong activist Stephen Donaldson.
Columbia University campus military groups include the U.S. Military Veterans of Columbia University and Advocates for Columbia ROTC. In the 2005–06 academic year, the Columbia Military Society, Columbia's student group for ROTC cadets and Marine officer candidates, was renamed the Hamilton Society for "students who aspire to serve their nation through the military in the tradition of Alexander Hamilton".
The largest student service organization at Columbia is Community Impact (CI). Founded in 1981, CI provides food, clothing, shelter, education, job training, and companionship for residents in its surrounding communities. CI consists of about 950 Columbia University student volunteers participating in 25 community service programs, which serve more than 8,000 people each year.
Columbia has several secret societies, including St. Anthony Hall, which was founded at the university in 1847, and two senior societies, the Nacoms and Sachems.
The Varsity Show is one of the oldest traditions at Columbia. Founded in 1893 as a fundraiser for the university's fledgling athletic teams, the Varsity Show now draws together the entire Columbia undergraduate community for a series of performances every April. Dedicated to producing a unique full-length musical that skewers and satirizes many dubious aspects of life at Columbia, the Varsity Show is written and performed exclusively by university undergraduates. Various renowned playwrights, composers, authors, directors, and actors have contributed to the Varsity Show, either as writers or performers, while students at Columbia, including Richard Rodgers, Oscar Hammerstein II, Lorenz Hart, Herman J. Mankiewicz, I. A. L. Diamond, Herman Wouk, Greta Gerwig, and Kate McKinnon.
Notable past shows include Fly With Me (1920), The Streets of New York (1948), The Sky's the Limit (1954), and Angels at Columbia (1994). In particular, Streets of New York, after having been revived three times, opened off-Broadway in 1963 and was awarded a 1964 Drama Desk Award. The Mischief Maker (1903), written by Edgar Allan Woolf and Cassius Freeborn, premiered at Madison Square Garden in 1906 as Mam'zelle Champagne.
The campus Tree Lighting ceremony was inaugurated in 1998. It celebrates the illumination of the medium-sized trees lining College Walk in front of Kent Hall and Hamilton Hall on the east end and Dodge Hall and Pulitzer Hall on the west, just before finals week in early December. The lights remain on until February 28. Students meet at the sundial for free hot chocolate, performances by a cappella groups, and speeches by the university president and a guest.
Immediately following the College Walk festivities is one of Columbia's older holiday traditions, the lighting of the Yule Log. The Christmas ceremony dates to a period prior to the American Revolutionary War, but lapsed before being revived by President Nicholas Murray Butler in 1910. A troop of students dressed as Continental Army soldiers carry the eponymous log from the sundial to the lounge of John Jay Hall, where it is lit amid the singing of seasonal carols. The Christmas ceremony is accompanied by a reading of A Visit From St. Nicholas by Clement Clarke Moore and Yes, Virginia, There is a Santa Claus by Francis Pharcellus Church.
The university has graduated many notable alumni, including five Founding Fathers of the United States, an author of the United States Constitution and a member of the Committee of Five. Three United States presidents have attended Columbia, as well as ten Justices of the Supreme Court of the United States, including three Chief Justices. As of 2011, 125 Pulitzer Prize winners and 39 Oscar winners have attended Columbia. As of 2006, there were 101 National Academy members who were alumni.
In a 2016 ranking of universities worldwide with respect to living graduates who are billionaires, Columbia ranked second, after Harvard.
Former U.S. Presidents Theodore Roosevelt and Franklin Delano Roosevelt attended the law school. Other political figures educated at Columbia include former U.S. President Barack Obama, Associate Justice of the U.S. Supreme Court Ruth Bader Ginsburg, former U.S. Secretary of State Madeleine Albright, former chairman of the U.S. Federal Reserve Bank Alan Greenspan, U.S. Attorney General Eric Holder, and U.S. Solicitor General Donald Verrilli Jr. The university has also educated 29 foreign heads of state, including president of Georgia Mikheil Saakashvili, president of East Timor Jose Ramos Horta, president of Estonia Toomas Hendrik Ilves and other historical figures such as Wellington Koo, Radovan Karadžić, Gaston Eyskens, and T. V. Soong. One of the architects of the Constitution of India, B. R. Ambedkar, was an alumnus.
Alumni of Columbia have occupied top positions in Wall Street and the rest of the business world. Notable members of the Astor family attended Columbia, while other business graduates include investor Warren Buffett, former CEO of PBS and NBC Larry Grossman, chairman of Wal-Mart S. Robson Walton, Bain Capital Co-Managing Partner, Jonathan Lavine, Thomson Reuters CEO Tom Glocer, New York Stock Exchange president Lynn Martin, and AllianceBernstein Chairman and CEO Lewis A. Sanders. CEO's of top Fortune 500 companies include James P. Gorman of Morgan Stanley, Robert J. Stevens of Lockheed Martin, Philippe Dauman of Viacom, Robert Bakish of Paramount Global, Ursula Burns of Xerox, Devin Wenig of EBay, Vikram Pandit of Citigroup, Ralph Izzo of Public Service Enterprise Group, Gail Koziara Boudreaux of Anthem, and Frank Blake of The Home Depot. Notable labor organizer and women's educator Louise Leonard McLaren received her degree of Master of Arts from Columbia.
In science and technology, Columbia alumni include: founder of IBM Herman Hollerith; inventor of FM radio Edwin Armstrong; Francis Mechner; integral in development of the nuclear submarine Hyman Rickover; founder of Google China Kai-Fu Lee; scientists Stephen Jay Gould, Robert Millikan, Helium–neon laser inventor Ali Javan and Mihajlo Pupin; chief-engineer of the New York City Subway, William Barclay Parsons; philosophers Irwin Edman and Robert Nozick; economist Milton Friedman; psychologist Harriet Babcock; archaeologist Josephine Platner Shear; and sociologists Lewis A. Coser and Rose Laub Coser.
Many Columbia alumni have gone on to renowned careers in the arts, including composers Richard Rodgers, Oscar Hammerstein II, Lorenz Hart, and Art Garfunkel; and painter Georgia O'Keeffe. Five United States Poet Laureates received their degrees from Columbia. Columbia alumni have made an indelible mark in the field of American poetry and literature, with such people as Jack Kerouac and Allen Ginsberg, pioneers of the Beat Generation; and Langston Hughes and Zora Neale Hurston, seminal figures in the Harlem Renaissance, all having attended the university. Other notable writers who attended Columbia include authors Isaac Asimov, J.D. Salinger, Upton Sinclair, Ursula K. Le Guin, Danielle Valore Evans, and Hunter S. Thompson. In architecture, William Lee Stoddart, a prolific architect of U.S. East Coast hotels, is an alumnus.
University alumni have also been very prominent in the film industry, with 33 alumni and former students winning a combined 43 Academy Awards (as of 2011). Some notable Columbia alumni that have gone on to work in film include directors Sidney Lumet (12 Angry Men) and Kathryn Bigelow (The Hurt Locker), screenwriters Howard Koch (Casablanca) and Joseph L. Mankiewicz (All About Eve), and actors James Cagney, Ed Harris and Timothée Chalamet.
As of 2021, Columbia employs 4,381 faculty, including 70 members of the National Academy of Sciences, 178 members of the American Academy of Arts and Sciences, and 65 members of the National Academy of Medicine. In total, the Columbia faculty has included 52 Nobel laureates, 12 National Medal of Science recipients, and 32 National Academy of Engineering members.
Columbia University faculty played particularly important roles during World War II and the creation of the New Deal under President Franklin D. Roosevelt, who attended Columbia Law School. The three core members of Roosevelt's Brain Trust: Adolf A. Berle, Raymond Moley, and Rexford Tugwell, were law professors at Columbia. The Statistical Research Group, which used statistics to analyze military problems during World War II, was composed of Columbia researchers and faculty including George Stigler and Milton Friedman. Columbia faculty and researchers, including Enrico Fermi, Leo Szilard, Eugene T. Booth, John R. Dunning, George B. Pegram, Walter Zinn, Chien-Shiung Wu, Francis G. Slack, Harold Urey, Herbert L. Anderson, and Isidor Isaac Rabi, also played a significant role during the early phases of the Manhattan Project.
Following the rise of Nazi Germany, the exiled Institute for Social Research at Goethe University Frankfurt would affiliate itself with Columbia from 1934 to 1950. It was during this period that thinkers including Theodor Adorno, Max Horkheimer, and Herbert Marcuse wrote and published some of the most seminal works of the Frankfurt School, including Reason and Revolution, Dialectic of Enlightenment, and Eclipse of Reason. Professors Edward Said, author of Orientalism, and Gayatri Spivak are generally considered as founders of the field of postcolonialism; other professors that have significantly contributed to the field include Hamid Dabashi and Joseph Massad. The works of professors Kimberlé Crenshaw, Patricia J. Williams, and Kendall Thomas were foundational to the field of critical race theory.
Columbia and its affiliated faculty have also made significant contributions to the study of religion. The affiliated Union Theological Seminary is a center of liberal Christianity in the United States, having served as the birthplace of Black theology through the efforts of faculty including James H. Cone and Cornel West, and Womanist theology, through the works of Katie Cannon, Emilie Townes, and Delores S. Williams. Likewise, the Jewish Theological Seminary of America was the birthplace of Conservative Judaism movement in the United States, which was founded and led by faculty members including Solomon Schechter, Alexander Kohut, and Louis Ginzberg in the early 20th century, and is a major center for Jewish studies in general.
Other schools of thought in the humanities Columbia professors made significant contributions toward include the Dunning School, founded by William Archibald Dunning; the anthropological schools of historical particularism and cultural relativism, founded by Franz Boas; and functional psychology, whose founders and proponents include John Dewey, James McKeen Cattell, Edward L. Thorndike, and Robert S. Woodworth.
Notable figures that have served as the president of Columbia University include 34th President of the United States Dwight D. Eisenhower, 4th Vice President of the United States George Clinton, Founding Father and U.S. Senator from Connecticut William Samuel Johnson, Nobel Peace Prize laureate Nicholas Murray Butler, and First Amendment scholar Lee Bollinger..
Notable Columbia University faculty include Zbigniew Brzezinski, Sonia Sotomayor, Kimberlé Crenshaw, Lee Bollinger, Franz Boas, Margaret Mead, Edward Sapir, John Dewey, Charles A. Beard, Max Horkheimer, Herbert Marcuse, Edward Said, Gayatri Chakravorty Spivak, Orhan Pamuk, Edwin Howard Armstrong, Enrico Fermi, Chien-Shiung Wu, Tsung-Dao Lee, Jack Steinberger, Joachim Frank, Joseph Stiglitz, Jeffrey Sachs, Robert Mundell, Thomas Hunt Morgan, Eric Kandel, Richard Axel, and Andrei Okounkov. | [
{
"paragraph_id": 0,
"text": "Columbia University, officially Columbia University in the City of New York, is a private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhattan, it is the oldest institution of higher education in New York and the fifth-oldest in the United States.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Columbia was established as a colonial college by royal charter under George II of Great Britain. It was renamed Columbia College in 1784 following the American Revolution, and in 1787 was placed under a private board of trustees headed by former students Alexander Hamilton and John Jay. In 1896, the campus was moved to its current location in Morningside Heights and renamed Columbia University.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Columbia is organized into twenty schools, including four undergraduate schools and 16 graduate schools. The university's research efforts include the Lamont–Doherty Earth Observatory, the Goddard Institute for Space Studies, and accelerator laboratories with Big Tech firms such as Amazon and IBM. Columbia is a founding member of the Association of American Universities and was the first school in the United States to grant the MD degree. The university also annually administers the Pulitzer Prize. Its endowment stands at $13.3 billion as of 2022, which is among the largest of any academic institution.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Columbia scientists and scholars have played a pivotal role in scientific breakthroughs including brain-computer interface; the laser and maser; nuclear magnetic resonance; the first nuclear pile; the first nuclear fission reaction in the Americas; the first evidence for plate tectonics and continental drift; and much of the initial research and planning for the Manhattan Project during World War II.",
"title": ""
},
{
"paragraph_id": 4,
"text": "As of December 2021, its alumni, faculty, and staff have included seven Founding Fathers of the United States; four U.S. presidents; 34 foreign heads of state; two secretaries-general of the United Nations; ten justices of the United States Supreme Court; 103 Nobel laureates; 125 National Academy of Sciences members; 53 living billionaires; 23 Olympic medalists; 33 Academy Award winners; and 125 Pulitzer Prize recipients.",
"title": ""
},
{
"paragraph_id": 5,
"text": "Discussions regarding the founding of a college in the Province of New York began as early as 1704, at which time Colonel Lewis Morris wrote to the Society for the Propagation of the Gospel in Foreign Parts, the missionary arm of the Church of England, persuading the society that New York City was an ideal community in which to establish a college. However, it was not until the founding of the College of New Jersey (renamed Princeton) across the Hudson River in New Jersey that the City of New York seriously considered founding a college. In 1746, an act was passed by the general assembly of New York to raise funds for the foundation of a new college. In 1751, the assembly appointed a commission of ten New York residents, seven of whom were members of the Church of England, to direct the funds accrued by the state lottery towards the foundation of a college.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "Classes were initially held in July 1754 and were presided over by the college's first president, Samuel Johnson. Johnson was the only instructor of the college's first class, which consisted of a mere eight students. Instruction was held in a new schoolhouse adjoining Trinity Church, located on what is now lower Broadway in Manhattan. The college was officially founded on October 31, 1754, as King's College by royal charter of George II, making it the oldest institution of higher learning in the State of New York and the fifth oldest in the United States.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "In 1763, Johnson was succeeded in the presidency by Myles Cooper, a graduate of The Queen's College, Oxford, and an ardent Tory. In the charged political climate of the American Revolution, his chief opponent in discussions at the college was an undergraduate of the class of 1777, Alexander Hamilton. The Irish anatomist, Samuel Clossy, was appointed professor of natural philosophy in October 1765 and later the college's first professor of anatomy in 1767. The American Revolutionary War broke out in 1776, and was catastrophic for the operation of King's College, which suspended instruction for eight years beginning in 1776 with the arrival of the Continental Army. The suspension continued through the military occupation of New York City by British troops until their departure in 1783. The college's library was looted and its sole building requisitioned for use as a military hospital first by American and then British forces.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "After the Revolutionary War, the college turned to the State of New York in order to restore its vitality, promising to make whatever changes to the school's charter the state might demand. The legislature agreed to assist the college, and on May 1, 1784, it passed \"an Act for granting certain privileges to the College heretofore called King's College\". The Act created a board of regents to oversee the resuscitation of King's College, and, in an effort to demonstrate its support for the new Republic, the legislature stipulated that \"the College within the City of New York heretofore called King's College be forever hereafter called and known by the name of Columbia College\", a reference to Columbia, an alternative name for America which in turn comes from the name of Christopher Columbus. The Regents finally became aware of the college's defective constitution in February 1787 and appointed a revision committee, which was headed by John Jay and Alexander Hamilton. In April of that same year, a new charter was adopted for the college granted the power to a separate board of 24 trustees.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "On May 21, 1787, William Samuel Johnson, the son of Samuel Johnson, was unanimously elected president of Columbia College. Prior to serving at the university, Johnson had participated in the First Continental Congress and been chosen as a delegate to the Constitutional Convention. For a period in the 1790s, with New York City as the federal and state capital and the country under successive Federalist governments, a revived Columbia thrived under the auspices of Federalists such as Hamilton and Jay. President George Washington and Vice President John Adams, in addition to both houses of Congress attended the college's commencement on May 6, 1789, as a tribute of honor to the many alumni of the school who had been involved in the American Revolution.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "In November 1813, the college agreed to incorporate its medical school with The College of Physicians and Surgeons, a new school created by the Regents of New York, forming Columbia University College of Physicians and Surgeons. The college's enrollment, structure, and academics stagnated for the majority of the 19th century, with many of the college presidents doing little to change the way that the college functioned. In 1857, the college moved from the King's College campus at Park Place to a primarily Gothic Revival campus on 49th Street and Madison Avenue, where it remained for the next forty years.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "During the last half of the 19th century, under the leadership of President F.A.P. Barnard, the president that Barnard College is named after, the institution rapidly assumed the shape of a modern university. Barnard College was created in 1889 as a response to the university's refusal to accept women. By this time, the college's investments in New York real estate became a primary source of steady income for the school, mainly owing to the city's expanding population.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "In 1896, university president Seth Low moved the campus from 49th Street to its present location, a more spacious campus in the developing neighborhood of Morningside Heights. Under the leadership of Low's successor, Nicholas Murray Butler, who served for over four decades, Columbia rapidly became the nation's major institution for research, setting the multiversity model that later universities would adopt. Prior to becoming the president of Columbia University, Butler founded Teachers College, as a school to prepare home economists and manual art teachers for the children of the poor, with philanthropist Grace Hoadley Dodge. Teachers College is currently affiliated as the university's Graduate School of Education.",
"title": "History"
},
{
"paragraph_id": 13,
"text": "Research into the atom by faculty members John R. Dunning, I. I. Rabi, Enrico Fermi and Polykarp Kusch placed Columbia's physics department in the international spotlight in the 1940s after the first nuclear pile was built to start what became the Manhattan Project. In 1928, Seth Low Junior College was established by Columbia University in order to mitigate the number of Jewish applicants to Columbia College. The college was closed in 1936 due to the adverse effects of the Great Depression and its students were subsequently taught at Morningside Heights, although they did not belong to any college but to the university at large. There was an evening school called University Extension, which taught night classes, for a fee, to anyone willing to attend.",
"title": "History"
},
{
"paragraph_id": 14,
"text": "In 1947, the program was reorganized as an undergraduate college and designated the School of General Studies in response to the return of GIs after World War II. In 1995, the School of General Studies was again reorganized as a full-fledged liberal arts college for non-traditional students (those who have had an academic break of one year or more, or are pursuing dual-degrees) and was fully integrated into Columbia's traditional undergraduate curriculum. The same year, the Division of Special Programs, later called the School of Continuing Education and now the School of Professional Studies, was established to reprise the former role of University Extension. While the School of Professional Studies only offered non-degree programs for lifelong learners and high school students in its earliest stages, it now offers degree programs in a diverse range of professional and inter-disciplinary fields.",
"title": "History"
},
{
"paragraph_id": 15,
"text": "In the aftermath of World War II, the discipline of international relations became a major scholarly focus of the university, and in response, the School of International and Public Affairs was founded in 1946, drawing upon the resources of the faculties of political science, economics, and history. The Columbia University Bicentennial was celebrated in 1954.",
"title": "History"
},
{
"paragraph_id": 16,
"text": "During the 1960s Columbia experienced large-scale student activism, which reached a climax in the spring of 1968 when hundreds of students occupied buildings on campus. The incident forced the resignation of Columbia's president, Grayson Kirk, and the establishment of the University Senate.",
"title": "History"
},
{
"paragraph_id": 17,
"text": "Though several schools within the university had admitted women for years, Columbia College first admitted women in the fall of 1983, after a decade of failed negotiations with Barnard College, the all-female institution affiliated with the university, to merge the two schools. Barnard College still remains affiliated with Columbia, and all Barnard graduates are issued diplomas signed by the presidents of Columbia University and Barnard College.",
"title": "History"
},
{
"paragraph_id": 18,
"text": "During the late 20th century, the university underwent significant academic, structural, and administrative changes as it developed into a major research university. For much of the 19th century, the university consisted of decentralized and separate faculties specializing in Political Science, Philosophy, and Pure Science. In 1979, these faculties were merged into the Graduate School of Arts and Sciences.",
"title": "History"
},
{
"paragraph_id": 19,
"text": "In 1991, the faculties of Columbia College, the School of General Studies, the Graduate School of Arts and Sciences, the School of the Arts, and the School of Professional Studies were merged into the Faculty of Arts and Sciences, leading to the academic integration and centralized governance of these schools.",
"title": "History"
},
{
"paragraph_id": 20,
"text": "In 2010, the School of International and Public Affairs, which was previously a part of the Faculty of Arts and Sciences, became an independent faculty.",
"title": "History"
},
{
"paragraph_id": 21,
"text": "The majority of Columbia's graduate and undergraduate studies are conducted in the Upper Manhattan neighborhood of Morningside Heights on Seth Low's late-19th century vision of a university campus where all disciplines could be taught at one location. The campus was designed along Beaux-Arts planning principles by the architects McKim, Mead & White. Columbia's main campus occupies more than six city blocks, or 32 acres (13 ha), in Morningside Heights, New York City, a neighborhood that contains a number of academic institutions. The university owns over 7,800 apartments in Morningside Heights, housing faculty, graduate students, and staff. Almost two dozen undergraduate dormitories (purpose-built or converted) are located on campus or in Morningside Heights. Columbia University has an extensive tunnel system, more than a century old, with the oldest portions predating the present campus. Some of these remain accessible to the public, while others have been cordoned off.",
"title": "Campus"
},
{
"paragraph_id": 22,
"text": "The Nicholas Murray Butler Library, known simply as Butler Library, is the largest single library in the Columbia University Library System, and is one of the largest buildings on the campus. Proposed as \"South Hall\" by the university's former president Nicholas Murray Butler as expansion plans for Low Memorial Library stalled, the new library was funded by Edward Harkness, benefactor of Yale's residential college system, and designed by his favorite architect, James Gamble Rogers. It was completed in 1934 and renamed for Butler in 1946. The library design is neo-classical in style. Its facade features a row of columns in the Ionic order above which are inscribed the names of great writers, philosophers, and thinkers, most of whom are read by students engaged in the Core Curriculum of Columbia College. As of 2020, Columbia's library system includes over 15.0 million volumes, making it the eighth largest library system and fifth largest collegiate library system in the United States.",
"title": "Campus"
},
{
"paragraph_id": 23,
"text": "Several buildings on the Morningside Heights campus are listed on the National Register of Historic Places. Low Memorial Library, a National Historic Landmark and the centerpiece of the campus, is listed for its architectural significance. Philosophy Hall is listed as the site of the invention of FM radio. Also listed is Pupin Hall, another National Historic Landmark, which houses the physics and astronomy departments. Here the first experiments on the fission of uranium were conducted by Enrico Fermi. The uranium atom was split there ten days after the world's first atom-splitting in Copenhagen, Denmark. Other buildings listed include Casa Italiana, the Delta Psi, Alpha Chapter building of St. Anthony Hall, Earl Hall, and the buildings of the affiliated Union Theological Seminary.",
"title": "Campus"
},
{
"paragraph_id": 24,
"text": "A statue by sculptor Daniel Chester French called Alma Mater is centered on the front steps of Low Memorial Library. McKim, Mead & White invited French to build the sculpture in order to harmonize with the larger composition of the court and library in the center of the campus. Draped in an academic gown, the female figure of Alma Mater wears a crown of laurels and sits on a throne. The scroll-like arms of the throne end in lamps, representing sapientia and doctrina. A book signifying knowledge, balances on her lap, and an owl, the attribute of wisdom, is hidden in the folds of her gown. Her right hand holds a scepter composed of four sprays of wheat, terminating with a crown of King's College which refers to Columbia's origin as a royal charter institution in 1754. A local actress named Mary Lawton was said to have posed for parts of the sculpture. The statue was dedicated on September 23, 1903, as a gift of Mr. & Mrs. Robert Goelet, and was originally covered in golden leaf. During the Columbia University protests of 1968 a bomb damaged the sculpture, but it has since been repaired. The small hidden owl on the sculpture is also the subject of many Columbia legends, the main legend being that the first student in the freshmen class to find the hidden owl on the statue will be valedictorian, and that any subsequent Columbia male who finds it will marry a Barnard student, given that Barnard is a women's college.",
"title": "Campus"
},
{
"paragraph_id": 25,
"text": "\"The Steps\", alternatively known as \"Low Steps\" or the \"Urban Beach\", are a popular meeting area for Columbia students. The term refers to the long series of granite steps leading from the lower part of campus (South Field) to its upper terrace. With a design inspired by the City Beautiful movement, the steps of Low Library provides Columbia University and Barnard College students, faculty, and staff with a comfortable outdoor platform and space for informal gatherings, events, and ceremonies. McKim's classical facade epitomizes late 19th-century new-classical designs, with its columns and portico marking the entrance to an important structure.",
"title": "Campus"
},
{
"paragraph_id": 26,
"text": "In April 2007, the university purchased more than two-thirds of a 17 acres (6.9 ha) site for a new campus in Manhattanville, an industrial neighborhood to the north of the Morningside Heights campus. Stretching from 125th Street to 133rd Street, Columbia Manhattanville houses buildings for Columbia's Business School, School of International and Public Affairs, Columbia School of the Arts, and the Jerome L. Greene Center for Mind, Brain, and Behavior, where research will occur on neurodegenerative diseases such as Parkinson's and Alzheimer's. The $7 billion expansion plan included demolishing all buildings, except three that are historically significant (the Studebaker Building, Prentis Hall, and the Nash Building), eliminating the existing light industry and storage warehouses, and relocating tenants in 132 apartments. Replacing these buildings created 6.8 million square feet (630,000 m) of space for the university. Community activist groups in West Harlem fought the expansion for reasons ranging from property protection and fair exchange for land, to residents' rights. Subsequent public hearings drew neighborhood opposition. As of December 2008, the State of New York's Empire State Development Corporation approved use of eminent domain, which, through declaration of Manhattanville's \"blighted\" status, gives governmental bodies the right to appropriate private property for public use. On May 20, 2009, the New York State Public Authorities Control Board approved the Manhanttanville expansion plan.",
"title": "Campus"
},
{
"paragraph_id": 27,
"text": "NewYork-Presbyterian Hospital is affiliated with the medical schools of both Columbia University and Cornell University. According to U.S. News & World Report's \"2020–21 Best Hospitals Honor Roll and Medical Specialties Rankings\", it is ranked fourth overall and second among university hospitals. Columbia's medical school has a strategic partnership with New York State Psychiatric Institute, and is affiliated with 19 other hospitals in the U.S. and four hospitals in other countries. Health-related schools are located at the Columbia University Medical Center, a 20-acre (8.1 ha) campus located in the neighborhood of Washington Heights, fifty blocks uptown. Other teaching hospitals affiliated with Columbia through the NewYork-Presbyterian network include the Payne Whitney Clinic in Manhattan, and the Payne Whitney Westchester, a psychiatric institute located in White Plains, New York. On the northern tip of Manhattan island (in the neighborhood of Inwood), Columbia owns the 26-acre (11 ha) Baker Field, which includes the Lawrence A. Wien Stadium as well as facilities for field sports, outdoor track, and tennis. There is a third campus on the west bank of the Hudson River, the 157-acre (64 ha) Lamont–Doherty Earth Observatory and Earth Institute in Palisades, New York. A fourth is the 60-acre (24 ha) Nevis Laboratories in Irvington, New York, for the study of particle and motion physics. A satellite site in Paris holds classes at Reid Hall.",
"title": "Campus"
},
{
"paragraph_id": 28,
"text": "In 2006, the university established the Office of Environmental Stewardship to initiate, coordinate and implement programs to reduce the university's environmental footprint. The U.S. Green Building Council selected the university's Manhattanville plan for the Leadership in Energy and Environmental Design (LEED) Neighborhood Design pilot program. The plan commits to incorporating smart growth, new urbanism and \"green\" building design principles. Columbia is one of the 2030 Challenge Partners, a group of nine universities in the city of New York that have pledged to reduce their greenhouse emissions by 30% within the next ten years. Columbia University adopts LEED standards for all new construction and major renovations. The university requires a minimum of Silver, but through its design and review process seeks to achieve higher levels. This is especially challenging for lab and research buildings with their intensive energy use; however, the university also uses lab design guidelines that seek to maximize energy efficiency while protecting the safety of researchers.",
"title": "Campus"
},
{
"paragraph_id": 29,
"text": "Every Thursday and Sunday of the month, Columbia hosts a greenmarket where local farmers can sell their produce to residents of the city. In addition, from April to November Hodgson's farm, a local New York gardening center, joins the market bringing a large selection of plants and blooming flowers. The market is one of the many operated at different points throughout the city by the non-profit group GrowNYC. Dining services at Columbia spends 36 percent of its food budget on local products, in addition to serving sustainably harvested seafood and fair trade coffee on campus. Columbia has been rated \"B+\" by the 2011 College Sustainability Report Card for its environmental and sustainability initiatives.",
"title": "Campus"
},
{
"paragraph_id": 30,
"text": "According to the A. W. Kuchler U.S. potential natural vegetation types, Columbia University would have a dominant vegetation type of Appalachian Oak (104) with a dominant vegetation form of Eastern Hardwood Forest (25).",
"title": "Campus"
},
{
"paragraph_id": 31,
"text": "Columbia Transportation is the bus service of the university, operated by Academy Bus Lines. The buses are open to all Columbia faculty, students, Dodge Fitness Center members, and anyone else who holds a Columbia ID card. In addition, all TSC students can ride the buses.",
"title": "Campus"
},
{
"paragraph_id": 32,
"text": "In the New York City Subway, the train serves the university at 116th Street-Columbia University. The M4, M104 and M60 buses stop on Broadway while the M11 stops on Amsterdam Avenue.",
"title": "Campus"
},
{
"paragraph_id": 33,
"text": "Columbia University received 60,551 applications for the class of 2025 (entering 2021) and a total of around 2,218 were admitted to the two schools for an overall acceptance rate of 3.66%. Columbia is a racially diverse school, with approximately 52% of all students identifying themselves as persons of color. Additionally, 50% of all undergraduates received grants from Columbia. The average grant size awarded to these students is $46,516. In 2015–2016, annual undergraduate tuition at Columbia was $50,526 with a total cost of attendance of $65,860 (including room and board). The college is need-blind for domestic applicants.",
"title": "Academics"
},
{
"paragraph_id": 34,
"text": "Annual gifts, fund-raising, and an increase in spending from the university's endowment have allowed Columbia to extend generous financial aid packages to qualifying students. On April 11, 2007, Columbia University announced a $400 million donation from media billionaire alumnus John Kluge to be used exclusively for undergraduate financial aid. The donation is among the largest single gifts to higher education. As of 2008, undergraduates from families with incomes as high as $60,000 a year will have the projected cost of attending the university, including room, board, and academic fees, fully paid for by the university. That same year, the university ended loans for incoming and then-current students who were on financial aid, replacing loans that were traditionally part of aid packages with grants from the university. However, this does not apply to international students, transfer students, visiting students, or students in the School of General Studies. In the fall of 2010, admission to Columbia's undergraduate colleges Columbia College and the Fu Foundation School of Engineering and Applied Science (also known as SEAS or Columbia Engineering) began accepting the Common Application. The policy change made Columbia one of the last major academic institutions and the last Ivy League university to switch to the Common Application.",
"title": "Academics"
},
{
"paragraph_id": 35,
"text": "Scholarships are also given to undergraduate students by the admissions committee. Designations include John W. Kluge Scholars, John Jay Scholars, C. Prescott Davis Scholars, Global Scholars, Egleston Scholars, and Science Research Fellows. Named scholars are selected by the admission committee from first-year applicants. According to Columbia, the first four designated scholars \"distinguish themselves for their remarkable academic and personal achievements, dynamism, intellectual curiosity, the originality and independence of their thinking, and the diversity that stems from their different cultures and their varied educational experiences\".",
"title": "Academics"
},
{
"paragraph_id": 36,
"text": "In 1919, Columbia established a student application process characterized by The New York Times as \"the first modern college application\". The application required a photograph of the applicant, the maiden name of the applicant's mother, and the applicant's religious background.",
"title": "Academics"
},
{
"paragraph_id": 37,
"text": "Columbia University is an independent, privately supported, nonsectarian institution of higher education. Its official corporate name is \"The Trustees of Columbia University in the City of New York\". The university's first charter was granted in 1754 by King George II; however, its modern charter was first enacted in 1787 and last amended in 1810 by the New York State Legislature. The university is governed by 24 trustees, customarily including the president, who serves ex officio. The trustees themselves are responsible for choosing their successors. Six of the 24 are nominated from a pool of candidates recommended by the Columbia Alumni Association. Another six are nominated by the board in consultation with the executive committee of the University Senate. The remaining 12, including the president, are nominated by the trustees themselves through their internal processes. The term of office for trustees is six years. Generally, they serve for no more than two consecutive terms. The trustees appoint the president and other senior administrative officers of the university, and review and confirm faculty appointments as required. They determine the university's financial and investment policies, authorize the budget, supervise the endowment, direct the management of the university's real estate and other assets, and otherwise oversee the administration and management of the university.",
"title": "Academics"
},
{
"paragraph_id": 38,
"text": "The University Senate was established by the trustees after a university-wide referendum in 1969. It succeeded to the powers of the University Council, which was created in 1890 as a body of faculty, deans, and other administrators to regulate inter-Faculty affairs and consider issues of university-wide concern. The University Senate is a unicameral body consisting of 107 members drawn from all constituencies of the university. These include the president of the university, the provost, the deans of Columbia College and the Graduate School of Arts and Sciences, all of whom serve ex officio, and five additional representatives, appointed by the president, from the university's administration. The president serves as the Senate's presiding officer. The Senate is charged with reviewing the educational policies, physical development, budget, and external relations of the university. It oversees the welfare and academic freedom of the faculty and the welfare of students.",
"title": "Academics"
},
{
"paragraph_id": 39,
"text": "The president of Columbia University, who is selected by the trustees in consultation with the executive committee of the University Senate and who serves at the trustees' pleasure, is the chief executive officer of the university. Assisting the president in administering the university are the provost, the senior executive vice president, the executive vice president for health and biomedical sciences, several other vice presidents, the general counsel, the secretary of the university, and the deans of the faculties, all of whom are appointed by the trustees on the nomination of the president and serve at their pleasure. Minouche Shafik became the 20th president of Columbia University on July 1, 2023.",
"title": "Academics"
},
{
"paragraph_id": 40,
"text": "Columbia has four official undergraduate colleges: Columbia College, the liberal arts college offering the Bachelor of Arts degree; the Fu Foundation School of Engineering and Applied Science (also known as SEAS or Columbia Engineering), the engineering and applied science school offering the Bachelor of Science degree; the School of General Studies, the liberal arts college offering the Bachelor of Arts degree to non-traditional students undertaking full- or part-time study; and Barnard College. Barnard College is a women's liberal arts college and an academic affiliate in which students receive a Bachelor of Arts degree from Columbia University. Their degrees are signed by the presidents of Columbia University and Barnard College. Barnard students are also eligible to cross-register classes that are available through the Barnard Catalogue and alumnae can join the Columbia Alumni Association.",
"title": "Academics"
},
{
"paragraph_id": 41,
"text": "Joint degree programs are available through Union Theological Seminary, the Jewish Theological Seminary of America, and the Juilliard School. Teachers College and Barnard College are official faculties of the university; both colleges' presidents are deans under the university governance structure. The Columbia University Senate includes faculty and student representatives from Teachers College and Barnard College who serve two-year terms; all senators are accorded full voting privileges regarding matters impacting the entire university. Teachers College is an affiliated, financially independent graduate school with their own board of trustees. Pursuant to an affiliation agreement, Columbia is given the authority to confer \"degrees and diplomas\" to the graduates of Teachers College. The degrees are signed by presidents of Teachers College and Columbia University in a manner analogous to the university's other graduate schools. Columbia's General Studies school also has joint undergraduate programs available through University College London, Sciences Po, City University of Hong Kong, Trinity College Dublin, and the Juilliard School.",
"title": "Academics"
},
{
"paragraph_id": 42,
"text": "The university also has several Columbia Global Centers, in Amman, Beijing, Istanbul, Mumbai, Nairobi, Paris, Rio de Janeiro, Santiago, and Tunis.",
"title": "Academics"
},
{
"paragraph_id": 43,
"text": "Columbia students can study abroad for a semester or a year at partner institutions such as Sciences Po, École des hautes études en sciences sociales (EHESS), École normale supérieure (ENS), Panthéon-Sorbonne University, King's College London, London School of Economics, University College London and the University of Warwick. Select students can study at either the University of Oxford or the University of Cambridge for a year if approved by both Columbia and either Oxford or Cambridge. Columbia also has a dual MA program with the Aga Khan University in London.",
"title": "Academics"
},
{
"paragraph_id": 44,
"text": "Columbia University is ranked 12th in the United States and seventh globally for 2023–2024 by U.S. News & World Report. QS University Rankings listed Columbia as fifth in the United States. Ranked 15th among U.S. colleges for 2020 by The Wall Street Journal and Times Higher Education, in recent years it has been ranked as high as second. Individual colleges and schools were also nationally ranked by U.S. News & World Report for its 2021 edition. Columbia Law School was ranked fourth, the Mailman School of Public Health fourth, the School of Social Work tied for third, Columbia Business School eighth, the College of Physicians and Surgeons tied for sixth for research (and tied for 31st for primary care), the School of Nursing tied for 11th in the master's program and tied for first in the doctorate nursing program, and the Fu Foundation School of Engineering and Applied Science (graduate) was ranked tied for 14th.",
"title": "Academics"
},
{
"paragraph_id": 45,
"text": "In 2021, Columbia was ranked seventh in the world (sixth in the United States) by Academic Ranking of World Universities, sixth in the world by U.S. News & World Report, 19th in the world by QS World University Rankings, and 11th globally by Times Higher Education World University Rankings. It was ranked in the first tier of American research universities, along with Harvard, MIT, and Stanford, in the 2019 report from the Center for Measuring University Performance. Columbia's Graduate School of Architecture, Planning and Preservation was ranked the second most admired graduate program by Architectural Record in 2020.",
"title": "Academics"
},
{
"paragraph_id": 46,
"text": "In 2011, the Mines ParisTech: Professional Ranking of World Universities ranked Columbia third best university for forming CEOs in the US and 12th worldwide.",
"title": "Academics"
},
{
"paragraph_id": 47,
"text": "In 2022, Columbia's reporting of metrics used for university ranking was criticized by Professor of Mathematics Michael Thaddeus, who argued key data supporting the ranking was \"inaccurate, dubious or highly misleading.\" Subsequently, U.S. News & World Report \"unranked\" Columbia from its 2022 list of Best Colleges saying that it could not verify the data submitted by the university. In June 2023, Columbia University announced their undergraduate schools would no longer participate in U.S. News & World Report's rankings, following the lead of its law, medical and nursing schools. A press release cited concerns that such rankings unduly influence applicants and \"distill a university's profile into a composite of data categories.\"",
"title": "Academics"
},
{
"paragraph_id": 48,
"text": "Columbia is classified among \"R1: Doctoral Universities – Very high research activity\". Columbia was the first North American site where the uranium atom was split. The College of Physicians and Surgeons played a central role in developing the modern understanding of neuroscience with the publication of Principles of Neural Science, described by historian of science Katja Huenther as the \"neuroscience 'bible' \". The book was written by a team of Columbia researchers that included Nobel Prize winner Eric Kandel, James H. Schwartz, and Thomas Jessell. Columbia was the birthplace of FM radio and the laser. The first brain-computer interface capable of translating brain signals into speech was developed by neuroengineers at Columbia. The MPEG-2 algorithm of transmitting high quality audio and video over limited bandwidth was developed by Dimitris Anastassiou, a Columbia professor of electrical engineering. Biologist Martin Chalfie was the first to introduce the use of Green Fluorescent Protein (GFP) in labeling cells in intact organisms. Other inventions and products related to Columbia include Sequential Lateral Solidification (SLS) technology for making LCDs, System Management Arts (SMARTS), Session Initiation Protocol (SIP) (which is used for audio, video, chat, instant messaging and whiteboarding), pharmacopeia, Macromodel (software for computational chemistry), a new and better recipe for glass concrete, Blue LEDs, and Beamprop (used in photonics).",
"title": "Academics"
},
{
"paragraph_id": 49,
"text": "Columbia scientists have been credited with about 175 new inventions in the health sciences each year. More than 30 pharmaceutical products based on discoveries and inventions made at Columbia reached the market. These include Remicade (for arthritis), Reopro (for blood clot complications), Xalatan (for glaucoma), Benefix, Latanoprost (a glaucoma treatment), shoulder prosthesis, homocysteine (testing for cardiovascular disease), and Zolinza (for cancer therapy). Columbia Technology Ventures (formerly Science and Technology Ventures), as of 2008, manages some 600 patents and more than 250 active license agreements. Patent-related deals earned Columbia more than $230 million in the 2006 fiscal year, according to the university, more than any university in the world. Columbia owns many unique research facilities, such as the Columbia Institute for Tele-Information dedicated to telecommunications and the Goddard Institute for Space Studies, which is an astronomical observatory affiliated with NASA.",
"title": "Academics"
},
{
"paragraph_id": 50,
"text": "Columbia is a long-standing participant of the United States Department of Veterans Affairs Yellow Ribbon Program, allowing eligible veterans to pursue a Columbia undergraduate degree regardless of socioeconomic status for over 70 years. As a part of the Eisenhower Leader Development Program (ELDP) in partnership with the United States Military Academy at West Point, Columbia is the only school in the Ivy League to offer a graduate degree program in organizational psychology to aid military officers in tactical decision making and strategic management.",
"title": "Academics"
},
{
"paragraph_id": 51,
"text": "Several prestigious awards are administered by Columbia University, most notably the Pulitzer Prize and the Bancroft Prize in history. Other prizes, which are awarded by the Graduate School of Journalism, include the Alfred I. duPont–Columbia University Award, the National Magazine Awards, the Maria Moors Cabot Prizes, the John Chancellor Award, and the Lukas Prizes, which include the J. Anthony Lukas Book Prize and Mark Lynton History Prize. The university also administers the Louisa Gross Horwitz Prize, which is considered an important precursor to the Nobel Prize, 51 of its 101 recipients having gone on to win either a Nobel Prize in Physiology or Medicine or Nobel Prize in Chemistry as of October 2018; the W. Alden Spencer Award; the Vetlesen Prize, which is known as the Nobel Prize of geology; the Japan-U.S. Friendship Commission Prize for the Translation of Japanese Literature, the oldest such award; the Edwin Howard Armstrong award; the Calderone Prize in public health; and the Ditson Conductor's Award.",
"title": "Academics"
},
{
"paragraph_id": 52,
"text": "In 2020, Columbia University's student population was 31,455 (8,842 students in undergraduate programs and 22,613 in postgraduate programs), with 45% of the student population identifying themselves as a minority. Twenty-six percent of students at Columbia have family incomes below $60,000. 16% of students at Columbia receive Federal Pell Grants, which mostly go to students whose family incomes are below $40,000. Seventeen percent of students are the first member of their family to attend a four-year college.",
"title": "Student life"
},
{
"paragraph_id": 53,
"text": "On-campus housing is guaranteed for all four years as an undergraduate. Columbia College and the Fu Foundation School of Engineering and Applied Science (also known as SEAS or Columbia Engineering) share housing in the on-campus residence halls. First-year students usually live in one of the large residence halls situated around South Lawn: Carman Hall, Furnald Hall, Hartley Hall, John Jay Hall, or Wallach Hall (originally Livingston Hall). Upperclassmen participate in a room selection process, wherein students can pick to live in a mix of either corridor- or apartment-style housing with their friends. The Columbia University School of General Studies, Barnard College and graduate schools have their own apartment-style housing in the surrounding neighborhood.",
"title": "Student life"
},
{
"paragraph_id": 54,
"text": "Columbia University is home to many fraternities, sororities, and co-educational Greek organizations. Approximately 10–15% of undergraduate students are associated with Greek life. Many Barnard women also join Columbia sororities. There has been a Greek presence on campus since the establishment in 1836 of the Delta chapter of Alpha Delta Phi. The InterGreek Council is the self-governing student organization that provides guidelines and support to its member organizations within each of the three councils at Columbia, the Interfraternity Council, Panhellenic Council, and Multicultural Greek Council. The three council presidents bring their affiliated chapters together once a month to meet as one Greek community. The InterGreek Council meetings provide opportunity for member organizations to learn from each other, work together and advocate for community needs.",
"title": "Student life"
},
{
"paragraph_id": 55,
"text": "The Columbia Daily Spectator is the nation's second-oldest continuously operating daily student newspaper. The Blue and White is a monthly literary magazine established in 1890 that discusses campus life and local politics. Bwog, originally an offshoot of The Blue and White but now fully independent, is an online campus news and entertainment source. The Morningside Post is a student-run multimedia news publication.",
"title": "Student life"
},
{
"paragraph_id": 56,
"text": "Political publications include The Current, a journal of politics, culture and Jewish Affairs; the Columbia Political Review, the multi-partisan political magazine of the Columbia Political Union; and AdHoc, which denotes itself as the \"progressive\" campus magazine and deals largely with local political issues and arts events.",
"title": "Student life"
},
{
"paragraph_id": 57,
"text": "Columbia Magazine is the alumni magazine of Columbia, serving all 340,000+ of the university's alumni. Arts and literary publications include The Columbia Review, the nation's oldest college literary magazine; Surgam, the literary magazine of The Philolexian Society; Quarto, Columbia University's official undergraduate literary magazine; 4x4, a student-run alternative to Quarto; Columbia, a nationally regarded literary journal; the Columbia Journal of Literary Criticism; and The Mobius Strip, an online arts and literary magazine. Inside New York is an annual guidebook to New York City, written, edited, and published by Columbia undergraduates. Through a distribution agreement with Columbia University Press, the book is sold at major retailers and independent bookstores.",
"title": "Student life"
},
{
"paragraph_id": 58,
"text": "Columbia is home to numerous undergraduate academic publications. The Columbia Undergraduate Science Journal prints original science research in its two annual publications. The Journal of Politics & Society is a journal of undergraduate research in the social sciences; Publius is an undergraduate journal of politics established in 2008 and published biannually; the Columbia East Asia Review allows undergraduates throughout the world to publish original work on China, Japan, Korea, Tibet, and Vietnam and is supported by the Weatherhead East Asian Institute; The Birch is an undergraduate journal of Eastern European and Eurasian culture that is the first national student-run journal of its kind; the Columbia Economics Review is the undergraduate economic journal on research and policy supported by the Columbia Economics Department; and the Columbia Science Review is a science magazine that prints general interest articles and faculty profiles.",
"title": "Student life"
},
{
"paragraph_id": 59,
"text": "Humor publications on Columbia's campus include The Fed, a triweekly satire and investigative newspaper, and the Jester of Columbia. Other publications include The Columbian, the undergraduate colleges' annually published yearbook; the Gadfly, a biannual journal of popular philosophy produced by undergraduates; and Rhapsody in Blue, an undergraduate urban studies magazine. Professional journals published by academic departments at Columbia University include Current Musicology and The Journal of Philosophy. During the spring semester, graduate students in the Journalism School publish The Bronx Beat, a bi-weekly newspaper covering the South Bronx.",
"title": "Student life"
},
{
"paragraph_id": 60,
"text": "Founded in 1961 under the auspices of Columbia University's Graduate School of Journalism, the Columbia Journalism Review (CJR) examines day-to-day press performance as well as the forces that affect that performance. The magazine is published six times a year.",
"title": "Student life"
},
{
"paragraph_id": 61,
"text": "Former publications include the Columbia University Forum, a review of literature and cultural affairs distributed for free to alumni.",
"title": "Student life"
},
{
"paragraph_id": 62,
"text": "Columbia is home to two pioneers in undergraduate campus radio broadcasting, WKCR-FM and CTV. Many undergraduates are also involved with Barnard's radio station, WBAR. WKCR, the student run radio station that broadcasts to the Tri-state area, claims to be the oldest FM radio station in the world, owing to the university's affiliation with Major Edwin Armstrong. The station went operational on July 18, 1939, from a 400-foot antenna tower in Alpine, New Jersey, broadcasting the first FM transmission in the world. Initially, WKCR was not a radio station, but an organization concerned with the technology of radio communications. As membership grew, however, the nascent club turned its efforts to broadcasting. Armstrong helped the students in their early efforts, donating a microphone and turntables when they designed their first makeshift studio in a dorm room. The station has its studios on the second floor of Alfred Lerner Hall on the Morningside campus with its main transmitter tower at 4 Times Square in Midtown Manhattan. Columbia Television (CTV) is the nation's second oldest student television station and the home of CTV News, a weekly live news program produced by undergraduate students.",
"title": "Student life"
},
{
"paragraph_id": 63,
"text": "The Philolexian Society is a literary and debating club founded in 1802, making it the oldest student group at Columbia, as well as the third oldest collegiate literary society in the country. The society annually administers the Joyce Kilmer Memorial Bad Poetry Contest. The Columbia Parliamentary Debate Team competes in tournaments around the country as part of the American Parliamentary Debate Association, and hosts both high school and college tournaments on Columbia's campus, as well as public debates on issues affecting the university.",
"title": "Student life"
},
{
"paragraph_id": 64,
"text": "The Columbia International Relations Council and Association (CIRCA), oversees Columbia's Model United Nations activities. CIRCA hosts college and high school Model UN conferences, hosts speakers influential in international politics to speak on campus, and trains students from underprivileged schools in New York in Model UN.",
"title": "Student life"
},
{
"paragraph_id": 65,
"text": "Columbia is a top supplier of young engineering entrepreneurs for New York City. Over the past 20 years, graduates of Columbia established over 100 technology companies.",
"title": "Student life"
},
{
"paragraph_id": 66,
"text": "The Columbia University Organization of Rising Entrepreneurs (CORE) was founded in 1999. The student-run group aims to foster entrepreneurship on campus. Each year CORE hosts dozens of events, including talks, #StartupColumbia, a conference and venture competition for $250,000, and Ignite@CU, a weekend for undergrads interested in design, engineering, and entrepreneurship. Notable speakers include Peter Thiel, Jack Dorsey, Alexis Ohanian, Drew Houston, and Mark Cuban. As of 2006, CORE had awarded graduate and undergraduate students over $100,000 in seed capital.",
"title": "Student life"
},
{
"paragraph_id": 67,
"text": "CampusNetwork, an on-campus social networking site called Campus Network that preceded Facebook, was created and popularized by Columbia engineering student Adam Goldberg in 2003. Mark Zuckerberg later asked Goldberg to join him in Palo Alto to work on Facebook, but Goldberg declined the offer. The Fu Foundation School of Engineering and Applied Science offers a minor in Technical Entrepreneurship through its Center for Technology, Innovation, and Community Engagement. SEAS' entrepreneurship activities focus on community building initiatives in New York and worldwide, made possible through partners such as Microsoft Corporation.",
"title": "Student life"
},
{
"paragraph_id": 68,
"text": "On June 14, 2010, Mayor Michael R. Bloomberg launched the NYC Media Lab to promote innovations in New York's media industry. Situated at the New York University Tandon School of Engineering, the lab is a consortium of Columbia University, New York University, and New York City Economic Development Corporation acting to connect companies with universities in new technology research. The Lab is modeled after similar ones at MIT and Stanford, and was established with a $250,000 grant from the New York City Economic Development Corporation.",
"title": "Student life"
},
{
"paragraph_id": 69,
"text": "A member institution of the National Collegiate Athletic Association (NCAA) in Division I FCS, Columbia fields varsity teams in 29 sports and is a member of the Ivy League. The football Lions play home games at the 17,000-seat Robert K. Kraft Field at Lawrence A. Wien Stadium. The Baker Athletics Complex also includes facilities for baseball, softball, soccer, lacrosse, field hockey, tennis, track, and rowing, as well as the new Campbell Sports Center, which opened in January 2013. The basketball, fencing, swimming & diving, volleyball, and wrestling programs are based at the Dodge Physical Fitness Center on the main campus.",
"title": "Student life"
},
{
"paragraph_id": 70,
"text": "Former students include Baseball Hall of Famers Lou Gehrig and Eddie Collins, football Hall of Famer Sid Luckman, Marcellus Wiley, and world champion women's weightlifter Karyn Marshall. On May 17, 1939, fledgling NBC broadcast a doubleheader between the Columbia Lions and the Princeton Tigers at Columbia's Baker Field, making it the first televised regular athletic event in history.",
"title": "Student life"
},
{
"paragraph_id": 71,
"text": "Columbia University athletics has a long history, with many accomplishments in athletic fields. In 1870, Columbia played against Rutgers University in the second intercollegiate rugby football game in the history of the sport. Eight years later, Columbia crew won the famed Henley Royal Regatta in the first-ever defeat for an English crew rowing in English waters. In 1900, Olympian and Columbia College student Maxie Long set the first official world record in the 400 meters with a time of 47.8 seconds. In 1983, Columbia men's soccer went 18–0 and was ranked first in the nation, but lost to Indiana 1–0 in double overtime in the NCAA championship game; nevertheless, the team went further toward the NCAA title than any Ivy League soccer team in history. The football program unfortunately is best known for its record of futility set during the 1980s: between 1983 and 1988, the team lost 44 games in a row, which is still the record for the NCAA Football Championship Subdivision. The streak was broken on October 8, 1988, with a 16–13 victory over arch-rival Princeton University. That was the Lions' first victory at Wien Stadium, which had been opened during the losing streak and was already four years old. A new tradition has developed with the Liberty Cup. The Liberty Cup is awarded annually to the winner of the football game between Fordham and Columbia Universities, two of the only three NCAA Division I football teams in New York City.",
"title": "Student life"
},
{
"paragraph_id": 72,
"text": "Established in 2003 by university president Lee C. Bollinger, the World Leaders Forum at Columbia University provides the opportunity for undergraduate and graduate students alike to listen to world leaders in government, religion, industry, finance, and academia. The World Leaders Forum is a year-around event series that strives to provide a platform for uninhibited speech among nations and cultures, while educating students about problems and progress around the globe.",
"title": "Student life"
},
{
"paragraph_id": 73,
"text": "Past forum speakers include former president of the United States Bill Clinton, the prime minister of India Atal Bihari Vajpayee, former president of Ghana John Agyekum Kufuor, president of Afghanistan Hamid Karzai, prime minister of Russia Vladimir Putin, president of the Republic of Mozambique Joaquim Alberto Chissano, president of the Republic of Bolivia Carlos Diego Mesa Gisbert, president of the Republic of Romania Ion Iliescu, president of the Republic of Latvia Vaira Vīķe-Freiberga, the first female president of Finland Tarja Halonen, President Yudhoyono of Indonesia, President Pervez Musharraf of the Islamic Republic of Pakistan, Iraq President Jalal Talabani, the 14th Dalai Lama, president of the Islamic Republic of Iran Mahmoud Ahmadinejad, financier George Soros, Mayor of New York City Michael R. Bloomberg, President Václav Klaus of the Czech Republic, President Cristina Fernández de Kirchner of Argentina, former Secretary-General of the United Nations Kofi Annan, and Al Gore.",
"title": "Student life"
},
{
"paragraph_id": 74,
"text": "The Columbia University Orchestra was founded by composer Edward MacDowell in 1896, and is the oldest continually operating university orchestra in the United States. Undergraduate student composers at Columbia may choose to become involved with Columbia New Music, which sponsors concerts of music written by undergraduate students from all of Columbia's schools. The Notes and Keys, the oldest a cappella group at Columbia, was founded in 1909. There are a number of performing arts groups at Columbia dedicated to producing student theater, including the Columbia Players, King's Crown Shakespeare Troupe (KCST), Columbia Musical Theater Society (CMTS), NOMADS (New and Original Material Authored and Directed by Students), LateNite Theatre, Columbia University Performing Arts League (CUPAL), Black Theatre Ensemble (BTE), sketch comedy group Chowdah, and improvisational troupes Alfred and Fruit Paunch.",
"title": "Student life"
},
{
"paragraph_id": 75,
"text": "The Columbia Queer Alliance is the central Columbia student organization that represents the bisexual, lesbian, gay, transgender, and questioning student population. It is the oldest gay student organization in the world, founded as the Student Homophile League in 1967 by students including lifelong activist Stephen Donaldson.",
"title": "Student life"
},
{
"paragraph_id": 76,
"text": "Columbia University campus military groups include the U.S. Military Veterans of Columbia University and Advocates for Columbia ROTC. In the 2005–06 academic year, the Columbia Military Society, Columbia's student group for ROTC cadets and Marine officer candidates, was renamed the Hamilton Society for \"students who aspire to serve their nation through the military in the tradition of Alexander Hamilton\".",
"title": "Student life"
},
{
"paragraph_id": 77,
"text": "The largest student service organization at Columbia is Community Impact (CI). Founded in 1981, CI provides food, clothing, shelter, education, job training, and companionship for residents in its surrounding communities. CI consists of about 950 Columbia University student volunteers participating in 25 community service programs, which serve more than 8,000 people each year.",
"title": "Student life"
},
{
"paragraph_id": 78,
"text": "Columbia has several secret societies, including St. Anthony Hall, which was founded at the university in 1847, and two senior societies, the Nacoms and Sachems.",
"title": "Student life"
},
{
"paragraph_id": 79,
"text": "The Varsity Show is one of the oldest traditions at Columbia. Founded in 1893 as a fundraiser for the university's fledgling athletic teams, the Varsity Show now draws together the entire Columbia undergraduate community for a series of performances every April. Dedicated to producing a unique full-length musical that skewers and satirizes many dubious aspects of life at Columbia, the Varsity Show is written and performed exclusively by university undergraduates. Various renowned playwrights, composers, authors, directors, and actors have contributed to the Varsity Show, either as writers or performers, while students at Columbia, including Richard Rodgers, Oscar Hammerstein II, Lorenz Hart, Herman J. Mankiewicz, I. A. L. Diamond, Herman Wouk, Greta Gerwig, and Kate McKinnon.",
"title": "Traditions"
},
{
"paragraph_id": 80,
"text": "Notable past shows include Fly With Me (1920), The Streets of New York (1948), The Sky's the Limit (1954), and Angels at Columbia (1994). In particular, Streets of New York, after having been revived three times, opened off-Broadway in 1963 and was awarded a 1964 Drama Desk Award. The Mischief Maker (1903), written by Edgar Allan Woolf and Cassius Freeborn, premiered at Madison Square Garden in 1906 as Mam'zelle Champagne.",
"title": "Traditions"
},
{
"paragraph_id": 81,
"text": "The campus Tree Lighting ceremony was inaugurated in 1998. It celebrates the illumination of the medium-sized trees lining College Walk in front of Kent Hall and Hamilton Hall on the east end and Dodge Hall and Pulitzer Hall on the west, just before finals week in early December. The lights remain on until February 28. Students meet at the sundial for free hot chocolate, performances by a cappella groups, and speeches by the university president and a guest.",
"title": "Traditions"
},
{
"paragraph_id": 82,
"text": "Immediately following the College Walk festivities is one of Columbia's older holiday traditions, the lighting of the Yule Log. The Christmas ceremony dates to a period prior to the American Revolutionary War, but lapsed before being revived by President Nicholas Murray Butler in 1910. A troop of students dressed as Continental Army soldiers carry the eponymous log from the sundial to the lounge of John Jay Hall, where it is lit amid the singing of seasonal carols. The Christmas ceremony is accompanied by a reading of A Visit From St. Nicholas by Clement Clarke Moore and Yes, Virginia, There is a Santa Claus by Francis Pharcellus Church.",
"title": "Traditions"
},
{
"paragraph_id": 83,
"text": "The university has graduated many notable alumni, including five Founding Fathers of the United States, an author of the United States Constitution and a member of the Committee of Five. Three United States presidents have attended Columbia, as well as ten Justices of the Supreme Court of the United States, including three Chief Justices. As of 2011, 125 Pulitzer Prize winners and 39 Oscar winners have attended Columbia. As of 2006, there were 101 National Academy members who were alumni.",
"title": "Notable people"
},
{
"paragraph_id": 84,
"text": "In a 2016 ranking of universities worldwide with respect to living graduates who are billionaires, Columbia ranked second, after Harvard.",
"title": "Notable people"
},
{
"paragraph_id": 85,
"text": "Former U.S. Presidents Theodore Roosevelt and Franklin Delano Roosevelt attended the law school. Other political figures educated at Columbia include former U.S. President Barack Obama, Associate Justice of the U.S. Supreme Court Ruth Bader Ginsburg, former U.S. Secretary of State Madeleine Albright, former chairman of the U.S. Federal Reserve Bank Alan Greenspan, U.S. Attorney General Eric Holder, and U.S. Solicitor General Donald Verrilli Jr. The university has also educated 29 foreign heads of state, including president of Georgia Mikheil Saakashvili, president of East Timor Jose Ramos Horta, president of Estonia Toomas Hendrik Ilves and other historical figures such as Wellington Koo, Radovan Karadžić, Gaston Eyskens, and T. V. Soong. One of the architects of the Constitution of India, B. R. Ambedkar, was an alumnus.",
"title": "Notable people"
},
{
"paragraph_id": 86,
"text": "Alumni of Columbia have occupied top positions in Wall Street and the rest of the business world. Notable members of the Astor family attended Columbia, while other business graduates include investor Warren Buffett, former CEO of PBS and NBC Larry Grossman, chairman of Wal-Mart S. Robson Walton, Bain Capital Co-Managing Partner, Jonathan Lavine, Thomson Reuters CEO Tom Glocer, New York Stock Exchange president Lynn Martin, and AllianceBernstein Chairman and CEO Lewis A. Sanders. CEO's of top Fortune 500 companies include James P. Gorman of Morgan Stanley, Robert J. Stevens of Lockheed Martin, Philippe Dauman of Viacom, Robert Bakish of Paramount Global, Ursula Burns of Xerox, Devin Wenig of EBay, Vikram Pandit of Citigroup, Ralph Izzo of Public Service Enterprise Group, Gail Koziara Boudreaux of Anthem, and Frank Blake of The Home Depot. Notable labor organizer and women's educator Louise Leonard McLaren received her degree of Master of Arts from Columbia.",
"title": "Notable people"
},
{
"paragraph_id": 87,
"text": "In science and technology, Columbia alumni include: founder of IBM Herman Hollerith; inventor of FM radio Edwin Armstrong; Francis Mechner; integral in development of the nuclear submarine Hyman Rickover; founder of Google China Kai-Fu Lee; scientists Stephen Jay Gould, Robert Millikan, Helium–neon laser inventor Ali Javan and Mihajlo Pupin; chief-engineer of the New York City Subway, William Barclay Parsons; philosophers Irwin Edman and Robert Nozick; economist Milton Friedman; psychologist Harriet Babcock; archaeologist Josephine Platner Shear; and sociologists Lewis A. Coser and Rose Laub Coser.",
"title": "Notable people"
},
{
"paragraph_id": 88,
"text": "Many Columbia alumni have gone on to renowned careers in the arts, including composers Richard Rodgers, Oscar Hammerstein II, Lorenz Hart, and Art Garfunkel; and painter Georgia O'Keeffe. Five United States Poet Laureates received their degrees from Columbia. Columbia alumni have made an indelible mark in the field of American poetry and literature, with such people as Jack Kerouac and Allen Ginsberg, pioneers of the Beat Generation; and Langston Hughes and Zora Neale Hurston, seminal figures in the Harlem Renaissance, all having attended the university. Other notable writers who attended Columbia include authors Isaac Asimov, J.D. Salinger, Upton Sinclair, Ursula K. Le Guin, Danielle Valore Evans, and Hunter S. Thompson. In architecture, William Lee Stoddart, a prolific architect of U.S. East Coast hotels, is an alumnus.",
"title": "Notable people"
},
{
"paragraph_id": 89,
"text": "University alumni have also been very prominent in the film industry, with 33 alumni and former students winning a combined 43 Academy Awards (as of 2011). Some notable Columbia alumni that have gone on to work in film include directors Sidney Lumet (12 Angry Men) and Kathryn Bigelow (The Hurt Locker), screenwriters Howard Koch (Casablanca) and Joseph L. Mankiewicz (All About Eve), and actors James Cagney, Ed Harris and Timothée Chalamet.",
"title": "Notable people"
},
{
"paragraph_id": 90,
"text": "As of 2021, Columbia employs 4,381 faculty, including 70 members of the National Academy of Sciences, 178 members of the American Academy of Arts and Sciences, and 65 members of the National Academy of Medicine. In total, the Columbia faculty has included 52 Nobel laureates, 12 National Medal of Science recipients, and 32 National Academy of Engineering members.",
"title": "Notable people"
},
{
"paragraph_id": 91,
"text": "Columbia University faculty played particularly important roles during World War II and the creation of the New Deal under President Franklin D. Roosevelt, who attended Columbia Law School. The three core members of Roosevelt's Brain Trust: Adolf A. Berle, Raymond Moley, and Rexford Tugwell, were law professors at Columbia. The Statistical Research Group, which used statistics to analyze military problems during World War II, was composed of Columbia researchers and faculty including George Stigler and Milton Friedman. Columbia faculty and researchers, including Enrico Fermi, Leo Szilard, Eugene T. Booth, John R. Dunning, George B. Pegram, Walter Zinn, Chien-Shiung Wu, Francis G. Slack, Harold Urey, Herbert L. Anderson, and Isidor Isaac Rabi, also played a significant role during the early phases of the Manhattan Project.",
"title": "Notable people"
},
{
"paragraph_id": 92,
"text": "Following the rise of Nazi Germany, the exiled Institute for Social Research at Goethe University Frankfurt would affiliate itself with Columbia from 1934 to 1950. It was during this period that thinkers including Theodor Adorno, Max Horkheimer, and Herbert Marcuse wrote and published some of the most seminal works of the Frankfurt School, including Reason and Revolution, Dialectic of Enlightenment, and Eclipse of Reason. Professors Edward Said, author of Orientalism, and Gayatri Spivak are generally considered as founders of the field of postcolonialism; other professors that have significantly contributed to the field include Hamid Dabashi and Joseph Massad. The works of professors Kimberlé Crenshaw, Patricia J. Williams, and Kendall Thomas were foundational to the field of critical race theory.",
"title": "Notable people"
},
{
"paragraph_id": 93,
"text": "Columbia and its affiliated faculty have also made significant contributions to the study of religion. The affiliated Union Theological Seminary is a center of liberal Christianity in the United States, having served as the birthplace of Black theology through the efforts of faculty including James H. Cone and Cornel West, and Womanist theology, through the works of Katie Cannon, Emilie Townes, and Delores S. Williams. Likewise, the Jewish Theological Seminary of America was the birthplace of Conservative Judaism movement in the United States, which was founded and led by faculty members including Solomon Schechter, Alexander Kohut, and Louis Ginzberg in the early 20th century, and is a major center for Jewish studies in general.",
"title": "Notable people"
},
{
"paragraph_id": 94,
"text": "Other schools of thought in the humanities Columbia professors made significant contributions toward include the Dunning School, founded by William Archibald Dunning; the anthropological schools of historical particularism and cultural relativism, founded by Franz Boas; and functional psychology, whose founders and proponents include John Dewey, James McKeen Cattell, Edward L. Thorndike, and Robert S. Woodworth.",
"title": "Notable people"
},
{
"paragraph_id": 95,
"text": "Notable figures that have served as the president of Columbia University include 34th President of the United States Dwight D. Eisenhower, 4th Vice President of the United States George Clinton, Founding Father and U.S. Senator from Connecticut William Samuel Johnson, Nobel Peace Prize laureate Nicholas Murray Butler, and First Amendment scholar Lee Bollinger..",
"title": "Notable people"
},
{
"paragraph_id": 96,
"text": "Notable Columbia University faculty include Zbigniew Brzezinski, Sonia Sotomayor, Kimberlé Crenshaw, Lee Bollinger, Franz Boas, Margaret Mead, Edward Sapir, John Dewey, Charles A. Beard, Max Horkheimer, Herbert Marcuse, Edward Said, Gayatri Chakravorty Spivak, Orhan Pamuk, Edwin Howard Armstrong, Enrico Fermi, Chien-Shiung Wu, Tsung-Dao Lee, Jack Steinberger, Joachim Frank, Joseph Stiglitz, Jeffrey Sachs, Robert Mundell, Thomas Hunt Morgan, Eric Kandel, Richard Axel, and Andrei Okounkov.",
"title": "Notable people"
}
] | Columbia University, officially Columbia University in the City of New York, is a private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhattan, it is the oldest institution of higher education in New York and the fifth-oldest in the United States. Columbia was established as a colonial college by royal charter under George II of Great Britain. It was renamed Columbia College in 1784 following the American Revolution, and in 1787 was placed under a private board of trustees headed by former students Alexander Hamilton and John Jay. In 1896, the campus was moved to its current location in Morningside Heights and renamed Columbia University. Columbia is organized into twenty schools, including four undergraduate schools and 16 graduate schools. The university's research efforts include the Lamont–Doherty Earth Observatory, the Goddard Institute for Space Studies, and accelerator laboratories with Big Tech firms such as Amazon and IBM. Columbia is a founding member of the Association of American Universities and was the first school in the United States to grant the MD degree. The university also annually administers the Pulitzer Prize. Its endowment stands at $13.3 billion as of 2022, which is among the largest of any academic institution. Columbia scientists and scholars have played a pivotal role in scientific breakthroughs including brain-computer interface; the laser and maser; nuclear magnetic resonance; the first nuclear pile; the first nuclear fission reaction in the Americas; the first evidence for plate tectonics and continental drift; and much of the initial research and planning for the Manhattan Project during World War II. As of December 2021, its alumni, faculty, and staff have included seven Founding Fathers of the United States; four U.S. presidents; 34 foreign heads of state; two secretaries-general of the United Nations; ten justices of the United States Supreme Court; 103 Nobel laureates; 125 National Academy of Sciences members; 53 living billionaires; 23 Olympic medalists; 33 Academy Award winners; and 125 Pulitzer Prize recipients. | 2001-09-10T03:44:36Z | 2023-12-28T04:04:19Z | [
"Template:ISBN",
"Template:Convert",
"Template:NYC bus link",
"Template:Lang",
"Template:Multiple image",
"Template:Rp",
"Template:Clear",
"Template:Cbignore",
"Template:Short description",
"Template:Infobox university",
"Template:Efn",
"Template:Reflist",
"Template:Scholia",
"Template:Columbia",
"Template:Use mdy dates",
"Template:As of",
"Template:Further",
"Template:Navboxes",
"Template:Good article",
"Template:Cite news",
"Template:Authority control",
"Template:Commons category",
"Template:Col-break",
"Template:Cite magazine",
"Template:Official website",
"Template:Col-end",
"Template:Portal",
"Template:Webarchive",
"Template:Wide image",
"Template:Cleanup gallery",
"Template:Cite nycland",
"Template:Refn",
"Template:Infobox U.S. college admissions",
"Template:Small",
"Template:Other uses",
"Template:See also",
"Template:NYCS Broadway-Seventh north",
"Template:Infobox US university ranking",
"Template:Notelist",
"Template:Cite web",
"Template:NHLS url",
"Template:Cite book",
"Template:Pp",
"Template:Div col end",
"Template:Cite journal",
"Template:Main",
"Template:Circa",
"Template:'",
"Template:Bartable",
"Template:Citation",
"Template:Col-begin",
"Template:NYCS trains",
"Template:Div col"
] | https://en.wikipedia.org/wiki/Columbia_University |
6,312 | Cell wall | A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism. Cell walls are absent in many eukaryotes, including animals, but are present in some other ones like fungi, algae and plants, and in most prokaryotes (except mollicute bacteria). A major function is to act as pressure vessels, preventing over-expansion of the cell when water enters.
The composition of cell walls varies between taxonomic group and species and may depend on cell type and developmental stage. The primary cell wall of land plants is composed of the polysaccharides cellulose, hemicelluloses and pectin. Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae possess cell walls made of glycoproteins and polysaccharides such as carrageenan and agar that are absent from land plants. In bacteria, the cell wall is composed of peptidoglycan. The cell walls of archaea have various compositions, and may be formed of glycoprotein S-layers, pseudopeptidoglycan, or polysaccharides. Fungi possess cell walls made of the N-acetylglucosamine polymer chitin. Unusually, diatoms have a cell wall composed of biogenic silica.
A plant cell wall was first observed and named (simply as a "wall") by Robert Hooke in 1665. However, "the dead excrusion product of the living protoplast" was forgotten, for almost three centuries, being the subject of scientific interest mainly as a resource for industrial processing or in relation to animal or human health.
In 1804, Karl Rudolphi and J.H.F. Link proved that cells had independent cell walls. Before, it had been thought that cells shared walls and that fluid passed between them this way.
The mode of formation of the cell wall was controversial in the 19th century. Hugo von Mohl (1853, 1858) advocated the idea that the cell wall grows by apposition. Carl Nägeli (1858, 1862, 1863) believed that the growth of the wall in thickness and in area was due to a process termed intussusception. Each theory was improved in the following decades: the apposition (or lamination) theory by Eduard Strasburger (1882, 1889), and the intussusception theory by Julius Wiesner (1886).
In 1930, Ernst Münch coined the term apoplast in order to separate the "living" symplast from the "dead" plant region, the latter of which included the cell wall.
By the 1980s, some authors suggested replacing the term "cell wall", particularly as it was used for plants, with the more precise term "extracellular matrix", as used for animal cells, but others preferred the older term.
Cell walls serve similar purposes in those organisms that possess them. They may give cells rigidity and strength, offering protection against mechanical stress. The chemical composition and mechanical properties of the cell wall are linked with plant cell growth and morphogenesis. In multicellular organisms, they permit the organism to build and hold a definite shape. Cell walls also limit the entry of large molecules that may be toxic to the cell. They further permit the creation of stable osmotic environments by preventing osmotic lysis and helping to retain water. Their composition, properties, and form may change during the cell cycle and depend on growth conditions.
In most cells, the cell wall is flexible, meaning that it will bend rather than holding a fixed shape, but has considerable tensile strength. The apparent rigidity of primary plant tissues is enabled by cell walls, but is not due to the walls' stiffness. Hydraulic turgor pressure creates this rigidity, along with the wall structure. The flexibility of the cell walls is seen when plants wilt, so that the stems and leaves begin to droop, or in seaweeds that bend in water currents. As John Howland explains
Think of the cell wall as a wicker basket in which a balloon has been inflated so that it exerts pressure from the inside. Such a basket is very rigid and resistant to mechanical damage. Thus does the prokaryote cell (and eukaryotic cell that possesses a cell wall) gain strength from a flexible plasma membrane pressing against a rigid cell wall.
The apparent rigidity of the cell wall thus results from inflation of the cell contained within. This inflation is a result of the passive uptake of water.
In plants, a secondary cell wall is a thicker additional layer of cellulose which increases wall rigidity. Additional layers may be formed by lignin in xylem cell walls, or suberin in cork cell walls. These compounds are rigid and waterproof, making the secondary wall stiff. Both wood and bark cells of trees have secondary walls. Other parts of plants such as the leaf stalk may acquire similar reinforcement to resist the strain of physical forces.
The primary cell wall of most plant cells is freely permeable to small molecules including small proteins, with size exclusion estimated to be 30-60 kDa. The pH is an important factor governing the transport of molecules through cell walls.
Cell walls evolved independently in many groups.
The photosynthetic eukaryotes (so-called plant and algae) is one group with cellulose cell walls, where the cell wall is closely related to the evolution of multicellularity, terrestrialization and vascularization. The CesA cellulose synthase evolved in Cyanobacteria and was part of Archaeplastida since endosymbiosis; secondary endosymbiosis events transferred it (with the arabinogalactan proteins) further into brown algae and oomycetes. Plants later evolved various genes from CesA, including the Csl (cellulose synthase-like) family of proteins and additional Ces proteins. Combined with the various glycosyltransferases (GT), they enable more complex chemical structures to be built.
Fungi use a chitin-glucan-protein cell wall. They share the 1,3-β-glucan synthesis pathway with plants, using homologous GT48 family 1,3-Beta-glucan synthases to perform the task, suggesting that such an enzyme is very ancient within the eukaryotes. Their glycoproteins are rich in mannose. The cell wall might have evolved to deter viral infections. Proteins embedded in cell walls are variable, contained in tandem repeats subject to homologous recombination. An alternative scenario is that fungi started with a chitin-based cell wall and later acquired the GT-48 enzymes for the 1,3-β-glucans via horizontal gene transfer. The pathway leading to 1,6-β-glucan synthesis is not sufficiently known in either case.
The walls of plant cells must have sufficient tensile strength to withstand internal osmotic pressures of several times atmospheric pressure that result from the difference in solute concentration between the cell interior and external solutions. Plant cell walls vary from 0.1 to several µm in thickness.
Up to three strata or layers may be found in plant cell walls:
In the primary (growing) plant cell wall, the major carbohydrates are cellulose, hemicellulose and pectin. The cellulose microfibrils are linked via hemicellulosic tethers to form the cellulose-hemicellulose network, which is embedded in the pectin matrix. The most common hemicellulose in the primary cell wall is xyloglucan. In grass cell walls, xyloglucan and pectin are reduced in abundance and partially replaced by glucuronoarabinoxylan, another type of hemicellulose. Primary cell walls characteristically extend (grow) by a mechanism called acid growth, mediated by expansins, extracellular proteins activated by acidic conditions that modify the hydrogen bonds between pectin and cellulose. This functions to increase cell wall extensibility. The outer part of the primary cell wall of the plant epidermis is usually impregnated with cutin and wax, forming a permeability barrier known as the plant cuticle.
Secondary cell walls contain a wide range of additional compounds that modify their mechanical properties and permeability. The major polymers that make up wood (largely secondary cell walls) include:
Additionally, structural proteins (1-5%) are found in most plant cell walls; they are classified as hydroxyproline-rich glycoproteins (HRGP), arabinogalactan proteins (AGP), glycine-rich proteins (GRPs), and proline-rich proteins (PRPs). Each class of glycoprotein is defined by a characteristic, highly repetitive protein sequence. Most are glycosylated, contain hydroxyproline (Hyp) and become cross-linked in the cell wall. These proteins are often concentrated in specialized cells and in cell corners. Cell walls of the epidermis may contain cutin. The Casparian strip in the endodermis roots and cork cells of plant bark contain suberin. Both cutin and suberin are polyesters that function as permeability barriers to the movement of water. The relative composition of carbohydrates, secondary compounds and proteins varies between plants and between the cell type and age. Plant cells walls also contain numerous enzymes, such as hydrolases, esterases, peroxidases, and transglycosylases, that cut, trim and cross-link wall polymers.
Secondary walls - especially in grasses - may also contain microscopic silica crystals, which may strengthen the wall and protect it from herbivores.
Cell walls in some plant tissues also function as storage deposits for carbohydrates that can be broken down and resorbed to supply the metabolic and growth needs of the plant. For example, endosperm cell walls in the seeds of cereal grasses, nasturtium and other species, are rich in glucans and other polysaccharides that are readily digested by enzymes during seed germination to form simple sugars that nourish the growing embryo.
The middle lamella is laid down first, formed from the cell plate during cytokinesis, and the primary cell wall is then deposited inside the middle lamella. The actual structure of the cell wall is not clearly defined and several models exist - the covalently linked cross model, the tether model, the diffuse layer model and the stratified layer model. However, the primary cell wall, can be defined as composed of cellulose microfibrils aligned at all angles. Cellulose microfibrils are produced at the plasma membrane by the cellulose synthase complex, which is proposed to be made of a hexameric rosette that contains three cellulose synthase catalytic subunits for each of the six units. Microfibrils are held together by hydrogen bonds to provide a high tensile strength. The cells are held together and share the gelatinous membrane called the middle lamella, which contains magnesium and calcium pectates (salts of pectic acid). Cells interact though plasmodesmata, which are inter-connecting channels of cytoplasm that connect to the protoplasts of adjacent cells across the cell wall.
In some plants and cell types, after a maximum size or point in development has been reached, a secondary wall is constructed between the plasma membrane and primary wall. Unlike the primary wall, the cellulose microfibrils are aligned parallel in layers, the orientation changing slightly with each additional layer so that the structure becomes helicoidal. Cells with secondary cell walls can be rigid, as in the gritty sclereid cells in pear and quince fruit. Cell to cell communication is possible through pits in the secondary cell wall that allow plasmodesmata to connect cells through the secondary cell walls.
There are several groups of organisms that have been called "fungi". Some of these groups (Oomycete and Myxogastria) have been transferred out of the Kingdom Fungi, in part because of fundamental biochemical differences in the composition of the cell wall. Most true fungi have a cell wall consisting largely of chitin and other polysaccharides. True fungi do not have cellulose in their cell walls.
In fungi, the cell wall is the outer-most layer, external to the plasma membrane. The fungal cell wall is a matrix of three main components:
Like plants, algae have cell walls. Algal cell walls contain either polysaccharides (such as cellulose (a glucan)) or a variety of glycoproteins (Volvocales) or both. The inclusion of additional polysaccharides in algal cells walls is used as a feature for algal taxonomy.
Other compounds that may accumulate in algal cell walls include sporopollenin and calcium ions.
The group of algae known as the diatoms synthesize their cell walls (also known as frustules or valves) from silicic acid. Significantly, relative to the organic cell walls produced by other groups, silica frustules require less energy to synthesize (approximately 8%), potentially a major saving on the overall cell energy budget and possibly an explanation for higher growth rates in diatoms.
In brown algae, phlorotannins may be a constituent of the cell walls.
The group Oomycetes, also known as water molds, are saprotrophic plant pathogens like fungi. Until recently they were widely believed to be fungi, but structural and molecular evidence has led to their reclassification as heterokonts, related to autotrophic brown algae and diatoms. Unlike fungi, oomycetes typically possess cell walls of cellulose and glucans rather than chitin, although some genera (such as Achlya and Saprolegnia) do have chitin in their walls. The fraction of cellulose in the walls is no more than 4 to 20%, far less than the fraction of glucans. Oomycete cell walls also contain the amino acid hydroxyproline, which is not found in fungal cell walls.
The dictyostelids are another group formerly classified among the fungi. They are slime molds that feed as unicellular amoebae, but aggregate into a reproductive stalk and sporangium under certain conditions. Cells of the reproductive stalk, as well as the spores formed at the apex, possess a cellulose wall. The spore wall has three layers, the middle one composed primarily of cellulose, while the innermost is sensitive to cellulase and pronase.
Around the outside of the cell membrane is the bacterial cell wall. Bacterial cell walls are made of peptidoglycan (also called murein), which is made from polysaccharide chains cross-linked by unusual peptides containing D-amino acids. Bacterial cell walls are different from the cell walls of plants and fungi which are made of cellulose and chitin, respectively. The cell wall of bacteria is also distinct from that of Archaea, which do not contain peptidoglycan. The cell wall is essential to the survival of many bacteria, although L-form bacteria can be produced in the laboratory that lack a cell wall. The antibiotic penicillin is able to kill bacteria by preventing the cross-linking of peptidoglycan and this causes the cell wall to weaken and lyse. The lysozyme enzyme can also damage bacterial cell walls.
There are broadly speaking two different types of cell wall in bacteria, called gram-positive and gram-negative. The names originate from the reaction of cells to the Gram stain, a test long-employed for the classification of bacterial species.
Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids.
Gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins. Most bacteria have the gram-negative cell wall and only the Bacillota and Actinomycetota (previously known as the low G+C and high G+C gram-positive bacteria, respectively) have the alternative gram-positive arrangement.
These differences in structure produce differences in antibiotic susceptibility. The beta-lactam antibiotics (e.g. penicillin, cephalosporin) only work against gram-negative pathogens, such as Haemophilus influenzae or Pseudomonas aeruginosa. The gycopeptide antibiotics (e.g. vancomycin, teicoplanin, telavancin) only work against gram-positive pathogens such as Staphylococcus aureus
Although not truly unique, the cell walls of Archaea are unusual. Whereas peptidoglycan is a standard component of all bacterial cell walls, all archaeal cell walls lack peptidoglycan, though some methanogens have a cell wall made of a similar polymer called pseudopeptidoglycan. There are four types of cell wall currently known among the Archaea.
One type of archaeal cell wall is that composed of pseudopeptidoglycan (also called pseudomurein). This type of wall is found in some methanogens, such as Methanobacterium and Methanothermus. While the overall structure of archaeal pseudopeptidoglycan superficially resembles that of bacterial peptidoglycan, there are a number of significant chemical differences. Like the peptidoglycan found in bacterial cell walls, pseudopeptidoglycan consists of polymer chains of glycan cross-linked by short peptide connections. However, unlike peptidoglycan, the sugar N-acetylmuramic acid is replaced by N-acetyltalosaminuronic acid, and the two sugars are bonded with a β,1-3 glycosidic linkage instead of β,1-4. Additionally, the cross-linking peptides are L-amino acids rather than D-amino acids as they are in bacteria.
A second type of archaeal cell wall is found in Methanosarcina and Halococcus. This type of cell wall is composed entirely of a thick layer of polysaccharides, which may be sulfated in the case of Halococcus. Structure in this type of wall is complex and not fully investigated.
A third type of wall among the Archaea consists of glycoprotein, and occurs in the hyperthermophiles, Halobacterium, and some methanogens. In Halobacterium, the proteins in the wall have a high content of acidic amino acids, giving the wall an overall negative charge. The result is an unstable structure that is stabilized by the presence of large quantities of positive sodium ions that neutralize the charge. Consequently, Halobacterium thrives only under conditions with high salinity.
In other Archaea, such as Methanomicrobium and Desulfurococcus, the wall may be composed only of surface-layer proteins, known as an S-layer. S-layers are common in bacteria, where they serve as either the sole cell-wall component or an outer layer in conjunction with polysaccharides. Most Archaea are Gram-negative, though at least one Gram-positive member is known.
Many protists and bacteria produce other cell surface structures apart from cell walls, external (extracellular matrix) or internal. Many algae have a sheath or envelope of mucilage outside the cell made of exopolysaccharides. Diatoms build a frustule from silica extracted from the surrounding water; radiolarians, foraminiferans, testate amoebae and silicoflagellates also produce a skeleton from minerals, called test in some groups. Many green algae, such as Halimeda and the Dasycladales, and some red algae, the Corallinales, encase their cells in a secreted skeleton of calcium carbonate. In each case, the wall is rigid and essentially inorganic. It is the non-living component of cell. Some golden algae, ciliates and choanoflagellates produces a shell-like protective outer covering called lorica. Some dinoflagellates have a theca of cellulose plates, and coccolithophorids have coccoliths.
An extracellular matrix (ECM) is also present in metazoans. Its composition varies between cells, but collagens are the most abundant protein in the ECM. | [
{
"paragraph_id": 0,
"text": "A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism. Cell walls are absent in many eukaryotes, including animals, but are present in some other ones like fungi, algae and plants, and in most prokaryotes (except mollicute bacteria). A major function is to act as pressure vessels, preventing over-expansion of the cell when water enters.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The composition of cell walls varies between taxonomic group and species and may depend on cell type and developmental stage. The primary cell wall of land plants is composed of the polysaccharides cellulose, hemicelluloses and pectin. Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae possess cell walls made of glycoproteins and polysaccharides such as carrageenan and agar that are absent from land plants. In bacteria, the cell wall is composed of peptidoglycan. The cell walls of archaea have various compositions, and may be formed of glycoprotein S-layers, pseudopeptidoglycan, or polysaccharides. Fungi possess cell walls made of the N-acetylglucosamine polymer chitin. Unusually, diatoms have a cell wall composed of biogenic silica.",
"title": ""
},
{
"paragraph_id": 2,
"text": "A plant cell wall was first observed and named (simply as a \"wall\") by Robert Hooke in 1665. However, \"the dead excrusion product of the living protoplast\" was forgotten, for almost three centuries, being the subject of scientific interest mainly as a resource for industrial processing or in relation to animal or human health.",
"title": "History"
},
{
"paragraph_id": 3,
"text": "In 1804, Karl Rudolphi and J.H.F. Link proved that cells had independent cell walls. Before, it had been thought that cells shared walls and that fluid passed between them this way.",
"title": "History"
},
{
"paragraph_id": 4,
"text": "The mode of formation of the cell wall was controversial in the 19th century. Hugo von Mohl (1853, 1858) advocated the idea that the cell wall grows by apposition. Carl Nägeli (1858, 1862, 1863) believed that the growth of the wall in thickness and in area was due to a process termed intussusception. Each theory was improved in the following decades: the apposition (or lamination) theory by Eduard Strasburger (1882, 1889), and the intussusception theory by Julius Wiesner (1886).",
"title": "History"
},
{
"paragraph_id": 5,
"text": "In 1930, Ernst Münch coined the term apoplast in order to separate the \"living\" symplast from the \"dead\" plant region, the latter of which included the cell wall.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "By the 1980s, some authors suggested replacing the term \"cell wall\", particularly as it was used for plants, with the more precise term \"extracellular matrix\", as used for animal cells, but others preferred the older term.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "Cell walls serve similar purposes in those organisms that possess them. They may give cells rigidity and strength, offering protection against mechanical stress. The chemical composition and mechanical properties of the cell wall are linked with plant cell growth and morphogenesis. In multicellular organisms, they permit the organism to build and hold a definite shape. Cell walls also limit the entry of large molecules that may be toxic to the cell. They further permit the creation of stable osmotic environments by preventing osmotic lysis and helping to retain water. Their composition, properties, and form may change during the cell cycle and depend on growth conditions.",
"title": "Properties"
},
{
"paragraph_id": 8,
"text": "In most cells, the cell wall is flexible, meaning that it will bend rather than holding a fixed shape, but has considerable tensile strength. The apparent rigidity of primary plant tissues is enabled by cell walls, but is not due to the walls' stiffness. Hydraulic turgor pressure creates this rigidity, along with the wall structure. The flexibility of the cell walls is seen when plants wilt, so that the stems and leaves begin to droop, or in seaweeds that bend in water currents. As John Howland explains",
"title": "Properties"
},
{
"paragraph_id": 9,
"text": "Think of the cell wall as a wicker basket in which a balloon has been inflated so that it exerts pressure from the inside. Such a basket is very rigid and resistant to mechanical damage. Thus does the prokaryote cell (and eukaryotic cell that possesses a cell wall) gain strength from a flexible plasma membrane pressing against a rigid cell wall.",
"title": "Properties"
},
{
"paragraph_id": 10,
"text": "The apparent rigidity of the cell wall thus results from inflation of the cell contained within. This inflation is a result of the passive uptake of water.",
"title": "Properties"
},
{
"paragraph_id": 11,
"text": "In plants, a secondary cell wall is a thicker additional layer of cellulose which increases wall rigidity. Additional layers may be formed by lignin in xylem cell walls, or suberin in cork cell walls. These compounds are rigid and waterproof, making the secondary wall stiff. Both wood and bark cells of trees have secondary walls. Other parts of plants such as the leaf stalk may acquire similar reinforcement to resist the strain of physical forces.",
"title": "Properties"
},
{
"paragraph_id": 12,
"text": "The primary cell wall of most plant cells is freely permeable to small molecules including small proteins, with size exclusion estimated to be 30-60 kDa. The pH is an important factor governing the transport of molecules through cell walls.",
"title": "Properties"
},
{
"paragraph_id": 13,
"text": "Cell walls evolved independently in many groups.",
"title": "Evolution"
},
{
"paragraph_id": 14,
"text": "The photosynthetic eukaryotes (so-called plant and algae) is one group with cellulose cell walls, where the cell wall is closely related to the evolution of multicellularity, terrestrialization and vascularization. The CesA cellulose synthase evolved in Cyanobacteria and was part of Archaeplastida since endosymbiosis; secondary endosymbiosis events transferred it (with the arabinogalactan proteins) further into brown algae and oomycetes. Plants later evolved various genes from CesA, including the Csl (cellulose synthase-like) family of proteins and additional Ces proteins. Combined with the various glycosyltransferases (GT), they enable more complex chemical structures to be built.",
"title": "Evolution"
},
{
"paragraph_id": 15,
"text": "Fungi use a chitin-glucan-protein cell wall. They share the 1,3-β-glucan synthesis pathway with plants, using homologous GT48 family 1,3-Beta-glucan synthases to perform the task, suggesting that such an enzyme is very ancient within the eukaryotes. Their glycoproteins are rich in mannose. The cell wall might have evolved to deter viral infections. Proteins embedded in cell walls are variable, contained in tandem repeats subject to homologous recombination. An alternative scenario is that fungi started with a chitin-based cell wall and later acquired the GT-48 enzymes for the 1,3-β-glucans via horizontal gene transfer. The pathway leading to 1,6-β-glucan synthesis is not sufficiently known in either case.",
"title": "Evolution"
},
{
"paragraph_id": 16,
"text": "The walls of plant cells must have sufficient tensile strength to withstand internal osmotic pressures of several times atmospheric pressure that result from the difference in solute concentration between the cell interior and external solutions. Plant cell walls vary from 0.1 to several µm in thickness.",
"title": "Plant cell walls"
},
{
"paragraph_id": 17,
"text": "Up to three strata or layers may be found in plant cell walls:",
"title": "Plant cell walls"
},
{
"paragraph_id": 18,
"text": "In the primary (growing) plant cell wall, the major carbohydrates are cellulose, hemicellulose and pectin. The cellulose microfibrils are linked via hemicellulosic tethers to form the cellulose-hemicellulose network, which is embedded in the pectin matrix. The most common hemicellulose in the primary cell wall is xyloglucan. In grass cell walls, xyloglucan and pectin are reduced in abundance and partially replaced by glucuronoarabinoxylan, another type of hemicellulose. Primary cell walls characteristically extend (grow) by a mechanism called acid growth, mediated by expansins, extracellular proteins activated by acidic conditions that modify the hydrogen bonds between pectin and cellulose. This functions to increase cell wall extensibility. The outer part of the primary cell wall of the plant epidermis is usually impregnated with cutin and wax, forming a permeability barrier known as the plant cuticle.",
"title": "Plant cell walls"
},
{
"paragraph_id": 19,
"text": "Secondary cell walls contain a wide range of additional compounds that modify their mechanical properties and permeability. The major polymers that make up wood (largely secondary cell walls) include:",
"title": "Plant cell walls"
},
{
"paragraph_id": 20,
"text": "Additionally, structural proteins (1-5%) are found in most plant cell walls; they are classified as hydroxyproline-rich glycoproteins (HRGP), arabinogalactan proteins (AGP), glycine-rich proteins (GRPs), and proline-rich proteins (PRPs). Each class of glycoprotein is defined by a characteristic, highly repetitive protein sequence. Most are glycosylated, contain hydroxyproline (Hyp) and become cross-linked in the cell wall. These proteins are often concentrated in specialized cells and in cell corners. Cell walls of the epidermis may contain cutin. The Casparian strip in the endodermis roots and cork cells of plant bark contain suberin. Both cutin and suberin are polyesters that function as permeability barriers to the movement of water. The relative composition of carbohydrates, secondary compounds and proteins varies between plants and between the cell type and age. Plant cells walls also contain numerous enzymes, such as hydrolases, esterases, peroxidases, and transglycosylases, that cut, trim and cross-link wall polymers.",
"title": "Plant cell walls"
},
{
"paragraph_id": 21,
"text": "Secondary walls - especially in grasses - may also contain microscopic silica crystals, which may strengthen the wall and protect it from herbivores.",
"title": "Plant cell walls"
},
{
"paragraph_id": 22,
"text": "Cell walls in some plant tissues also function as storage deposits for carbohydrates that can be broken down and resorbed to supply the metabolic and growth needs of the plant. For example, endosperm cell walls in the seeds of cereal grasses, nasturtium and other species, are rich in glucans and other polysaccharides that are readily digested by enzymes during seed germination to form simple sugars that nourish the growing embryo.",
"title": "Plant cell walls"
},
{
"paragraph_id": 23,
"text": "The middle lamella is laid down first, formed from the cell plate during cytokinesis, and the primary cell wall is then deposited inside the middle lamella. The actual structure of the cell wall is not clearly defined and several models exist - the covalently linked cross model, the tether model, the diffuse layer model and the stratified layer model. However, the primary cell wall, can be defined as composed of cellulose microfibrils aligned at all angles. Cellulose microfibrils are produced at the plasma membrane by the cellulose synthase complex, which is proposed to be made of a hexameric rosette that contains three cellulose synthase catalytic subunits for each of the six units. Microfibrils are held together by hydrogen bonds to provide a high tensile strength. The cells are held together and share the gelatinous membrane called the middle lamella, which contains magnesium and calcium pectates (salts of pectic acid). Cells interact though plasmodesmata, which are inter-connecting channels of cytoplasm that connect to the protoplasts of adjacent cells across the cell wall.",
"title": "Plant cell walls"
},
{
"paragraph_id": 24,
"text": "In some plants and cell types, after a maximum size or point in development has been reached, a secondary wall is constructed between the plasma membrane and primary wall. Unlike the primary wall, the cellulose microfibrils are aligned parallel in layers, the orientation changing slightly with each additional layer so that the structure becomes helicoidal. Cells with secondary cell walls can be rigid, as in the gritty sclereid cells in pear and quince fruit. Cell to cell communication is possible through pits in the secondary cell wall that allow plasmodesmata to connect cells through the secondary cell walls.",
"title": "Plant cell walls"
},
{
"paragraph_id": 25,
"text": "There are several groups of organisms that have been called \"fungi\". Some of these groups (Oomycete and Myxogastria) have been transferred out of the Kingdom Fungi, in part because of fundamental biochemical differences in the composition of the cell wall. Most true fungi have a cell wall consisting largely of chitin and other polysaccharides. True fungi do not have cellulose in their cell walls.",
"title": "Fungal cell walls"
},
{
"paragraph_id": 26,
"text": "In fungi, the cell wall is the outer-most layer, external to the plasma membrane. The fungal cell wall is a matrix of three main components:",
"title": "Fungal cell walls"
},
{
"paragraph_id": 27,
"text": "Like plants, algae have cell walls. Algal cell walls contain either polysaccharides (such as cellulose (a glucan)) or a variety of glycoproteins (Volvocales) or both. The inclusion of additional polysaccharides in algal cells walls is used as a feature for algal taxonomy.",
"title": "Other eukaryotic cell walls"
},
{
"paragraph_id": 28,
"text": "Other compounds that may accumulate in algal cell walls include sporopollenin and calcium ions.",
"title": "Other eukaryotic cell walls"
},
{
"paragraph_id": 29,
"text": "The group of algae known as the diatoms synthesize their cell walls (also known as frustules or valves) from silicic acid. Significantly, relative to the organic cell walls produced by other groups, silica frustules require less energy to synthesize (approximately 8%), potentially a major saving on the overall cell energy budget and possibly an explanation for higher growth rates in diatoms.",
"title": "Other eukaryotic cell walls"
},
{
"paragraph_id": 30,
"text": "In brown algae, phlorotannins may be a constituent of the cell walls.",
"title": "Other eukaryotic cell walls"
},
{
"paragraph_id": 31,
"text": "The group Oomycetes, also known as water molds, are saprotrophic plant pathogens like fungi. Until recently they were widely believed to be fungi, but structural and molecular evidence has led to their reclassification as heterokonts, related to autotrophic brown algae and diatoms. Unlike fungi, oomycetes typically possess cell walls of cellulose and glucans rather than chitin, although some genera (such as Achlya and Saprolegnia) do have chitin in their walls. The fraction of cellulose in the walls is no more than 4 to 20%, far less than the fraction of glucans. Oomycete cell walls also contain the amino acid hydroxyproline, which is not found in fungal cell walls.",
"title": "Other eukaryotic cell walls"
},
{
"paragraph_id": 32,
"text": "The dictyostelids are another group formerly classified among the fungi. They are slime molds that feed as unicellular amoebae, but aggregate into a reproductive stalk and sporangium under certain conditions. Cells of the reproductive stalk, as well as the spores formed at the apex, possess a cellulose wall. The spore wall has three layers, the middle one composed primarily of cellulose, while the innermost is sensitive to cellulase and pronase.",
"title": "Other eukaryotic cell walls"
},
{
"paragraph_id": 33,
"text": "Around the outside of the cell membrane is the bacterial cell wall. Bacterial cell walls are made of peptidoglycan (also called murein), which is made from polysaccharide chains cross-linked by unusual peptides containing D-amino acids. Bacterial cell walls are different from the cell walls of plants and fungi which are made of cellulose and chitin, respectively. The cell wall of bacteria is also distinct from that of Archaea, which do not contain peptidoglycan. The cell wall is essential to the survival of many bacteria, although L-form bacteria can be produced in the laboratory that lack a cell wall. The antibiotic penicillin is able to kill bacteria by preventing the cross-linking of peptidoglycan and this causes the cell wall to weaken and lyse. The lysozyme enzyme can also damage bacterial cell walls.",
"title": "Prokaryotic cell walls"
},
{
"paragraph_id": 34,
"text": "There are broadly speaking two different types of cell wall in bacteria, called gram-positive and gram-negative. The names originate from the reaction of cells to the Gram stain, a test long-employed for the classification of bacterial species.",
"title": "Prokaryotic cell walls"
},
{
"paragraph_id": 35,
"text": "Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids.",
"title": "Prokaryotic cell walls"
},
{
"paragraph_id": 36,
"text": "Gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins. Most bacteria have the gram-negative cell wall and only the Bacillota and Actinomycetota (previously known as the low G+C and high G+C gram-positive bacteria, respectively) have the alternative gram-positive arrangement.",
"title": "Prokaryotic cell walls"
},
{
"paragraph_id": 37,
"text": "These differences in structure produce differences in antibiotic susceptibility. The beta-lactam antibiotics (e.g. penicillin, cephalosporin) only work against gram-negative pathogens, such as Haemophilus influenzae or Pseudomonas aeruginosa. The gycopeptide antibiotics (e.g. vancomycin, teicoplanin, telavancin) only work against gram-positive pathogens such as Staphylococcus aureus",
"title": "Prokaryotic cell walls"
},
{
"paragraph_id": 38,
"text": "Although not truly unique, the cell walls of Archaea are unusual. Whereas peptidoglycan is a standard component of all bacterial cell walls, all archaeal cell walls lack peptidoglycan, though some methanogens have a cell wall made of a similar polymer called pseudopeptidoglycan. There are four types of cell wall currently known among the Archaea.",
"title": "Prokaryotic cell walls"
},
{
"paragraph_id": 39,
"text": "One type of archaeal cell wall is that composed of pseudopeptidoglycan (also called pseudomurein). This type of wall is found in some methanogens, such as Methanobacterium and Methanothermus. While the overall structure of archaeal pseudopeptidoglycan superficially resembles that of bacterial peptidoglycan, there are a number of significant chemical differences. Like the peptidoglycan found in bacterial cell walls, pseudopeptidoglycan consists of polymer chains of glycan cross-linked by short peptide connections. However, unlike peptidoglycan, the sugar N-acetylmuramic acid is replaced by N-acetyltalosaminuronic acid, and the two sugars are bonded with a β,1-3 glycosidic linkage instead of β,1-4. Additionally, the cross-linking peptides are L-amino acids rather than D-amino acids as they are in bacteria.",
"title": "Prokaryotic cell walls"
},
{
"paragraph_id": 40,
"text": "A second type of archaeal cell wall is found in Methanosarcina and Halococcus. This type of cell wall is composed entirely of a thick layer of polysaccharides, which may be sulfated in the case of Halococcus. Structure in this type of wall is complex and not fully investigated.",
"title": "Prokaryotic cell walls"
},
{
"paragraph_id": 41,
"text": "A third type of wall among the Archaea consists of glycoprotein, and occurs in the hyperthermophiles, Halobacterium, and some methanogens. In Halobacterium, the proteins in the wall have a high content of acidic amino acids, giving the wall an overall negative charge. The result is an unstable structure that is stabilized by the presence of large quantities of positive sodium ions that neutralize the charge. Consequently, Halobacterium thrives only under conditions with high salinity.",
"title": "Prokaryotic cell walls"
},
{
"paragraph_id": 42,
"text": "In other Archaea, such as Methanomicrobium and Desulfurococcus, the wall may be composed only of surface-layer proteins, known as an S-layer. S-layers are common in bacteria, where they serve as either the sole cell-wall component or an outer layer in conjunction with polysaccharides. Most Archaea are Gram-negative, though at least one Gram-positive member is known.",
"title": "Prokaryotic cell walls"
},
{
"paragraph_id": 43,
"text": "Many protists and bacteria produce other cell surface structures apart from cell walls, external (extracellular matrix) or internal. Many algae have a sheath or envelope of mucilage outside the cell made of exopolysaccharides. Diatoms build a frustule from silica extracted from the surrounding water; radiolarians, foraminiferans, testate amoebae and silicoflagellates also produce a skeleton from minerals, called test in some groups. Many green algae, such as Halimeda and the Dasycladales, and some red algae, the Corallinales, encase their cells in a secreted skeleton of calcium carbonate. In each case, the wall is rigid and essentially inorganic. It is the non-living component of cell. Some golden algae, ciliates and choanoflagellates produces a shell-like protective outer covering called lorica. Some dinoflagellates have a theca of cellulose plates, and coccolithophorids have coccoliths.",
"title": "Other cell coverings"
},
{
"paragraph_id": 44,
"text": "An extracellular matrix (ECM) is also present in metazoans. Its composition varies between cells, but collagens are the most abundant protein in the ECM.",
"title": "Other cell coverings"
}
] | A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism. Cell walls are absent in many eukaryotes, including animals, but are present in some other ones like fungi, algae and plants, and in most prokaryotes. A major function is to act as pressure vessels, preventing over-expansion of the cell when water enters. The composition of cell walls varies between taxonomic group and species and may depend on cell type and developmental stage. The primary cell wall of land plants is composed of the polysaccharides cellulose, hemicelluloses and pectin. Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae possess cell walls made of glycoproteins and polysaccharides such as carrageenan and agar that are absent from land plants. In bacteria, the cell wall is composed of peptidoglycan. The cell walls of archaea have various compositions, and may be formed of glycoprotein S-layers, pseudopeptidoglycan, or polysaccharides. Fungi possess cell walls made of the N-acetylglucosamine polymer chitin. Unusually, diatoms have a cell wall composed of biogenic silica. | 2001-09-10T18:12:09Z | 2023-12-16T02:11:14Z | [
"Template:Short description",
"Template:Pp-vandalism",
"Template:More citations needed section",
"Template:Clarify",
"Template:Cite book",
"Template:Organelles",
"Template:Botany",
"Template:Protist",
"Template:Authority control",
"Template:Rp",
"Template:Blockquote",
"Template:Cite journal",
"Template:Cite web",
"Template:Bacteria",
"Template:Cell biology",
"Template:Clear",
"Template:Expand section",
"Template:Further",
"Template:Reflist",
"Template:Wiktionary",
"Template:Fungus structure"
] | https://en.wikipedia.org/wiki/Cell_wall |
6,313 | Classical element | The classical elements typically refer to earth, water, air, fire, and (later) aether which were proposed to explain the nature and complexity of all matter in terms of simpler substances. Ancient cultures in Greece, Tibet, and India had similar lists which sometimes referred, in local languages, to "air" as "wind" and the fifth element as "void".
These different cultures and even individual philosophers had widely varying explanations concerning their attributes and how they related to observable phenomena as well as cosmology. Sometimes these theories overlapped with mythology and were personified in deities. Some of these interpretations included atomism (the idea of very small, indivisible portions of matter), but other interpretations considered the elements to be divisible into infinitely small pieces without changing their nature.
While the classification of the material world in ancient India, Hellenistic Egypt, and ancient Greece into air, earth, fire, and water was more philosophical, during the Middle Ages medieval scientists used practical, experimental observation to classify materials. In Europe, the ancient Greek concept, devised by Empedocles, evolved into the systematic classifications of Aristotle and Hippocrates. This evolved slightly into the medieval system, and eventually became the object of experimental verification in the 1600s, at the start of the Scientific Revolution.
Modern science does not support the classical elements to classify types of substances. Atomic theory classifies atoms into more than a hundred chemical elements such as oxygen, iron, and mercury, which may form chemical compounds and mixtures. The modern categories roughly corresponding to the classical elements are the states of matter produced under different temperatures and pressures. Solid, liquid, gas, and plasma share many attributes with the corresponding classical elements of earth, water, air, and fire, but these states describe the similar behavior of different types of atoms at similar energy levels, not the characteristic behavior of certain atoms or substances.
The ancient Greek concept of four basic elements, these being earth (γῆ gê), water (ὕδωρ hýdōr), air (ἀήρ aḗr), and fire (πῦρ pŷr), dates from pre-Socratic times and persisted throughout the Middle Ages and into the Early modern period, deeply influencing European thought and culture.
The classical elements were first proposed independently by several early Pre-Socratic philosophers. Greek philosophers had debated which substance was the arche ("first principle"), or primordial element from which everything else was made. Thales (c. 626/623 – c. 548/545 BC) believed that water was this principle. Anaximander (c. 610 – c. 546 BC) argued that the primordial substance was not any of the known substances, but could be transformed into them, and they into each other. Anaximenes (c. 586 – c. 526 BC) favored air, and Heraclitus (fl. c. 500 BC) championed fire.
The Sicilian Greek philosopher Empedocles (c. 450 BC) was the first to propose the four classical elements as a set: fire, earth, air, and water. He called them the four "roots" (ῥιζώματα, rhizōmata). Empedocles also proved (at least to his own satisfaction) that air was a separate substance by observing that a bucket inverted in water did not become filled with water, a pocket of air remaining trapped inside.
Fire, earth, air, and water have become the popular most popular set in modern interpretations of the classical elements. One version is provided by Robert Boyle in The Sceptical Chymist, which was published in 1661 in the form of a dialogue between five characters. Themistius, the Aristotelian of the party, says:
If You but consider a piece of green-Wood burning in a Chimney, You will readily discern in the disbanded parts of it the four Elements, of which we teach It and other mixt bodies to be compos’d. The fire discovers it self in the flame ... the smoke by ascending to the top of the chimney, and there readily vanishing into air ... manifests to what Element it belongs and gladly returnes. The water ... boyling and hissing at the ends of the burning Wood betrayes it self ... and the ashes by their weight, their firiness, and their dryness, put it past doubt that they belong to the Element of Earth.
According to Galen, these elements were used by Hippocrates (c. 460 – c. 370 BC) in describing the human body with an association with the four humours: yellow bile (fire), black bile (earth), blood (air), and phlegm (water). Medical care was primarily about helping the patient stay in or return to their own personal natural balanced state.
Plato (428/423 – 348/347 BC) seems to have been the first to use the term "element (στοιχεῖον, stoicheîon)" in reference to air, fire, earth, and water. The ancient Greek word for element, stoicheion (from stoicheo, "to line up") meant "smallest division (of a sun-dial), a syllable", as the composing unit of an alphabet it could denote a letter and the smallest unit from which a word is formed.
In On the Heavens (350 BC), Aristotle defines "element" in general:
An element, we take it, is a body into which other bodies may be analysed, present in them potentially or in actuality (which of these, is still disputable), and not itself divisible into bodies different in form. That, or something like it, is what all men in every case mean by element.
In his On Generation and Corruption, Aristotle related each of the four elements to two of the four sensible qualities:
A classic diagram has one square inscribed in the other, with the corners of one being the classical elements, and the corners of the other being the properties. The opposite corner is the opposite of these properties, "hot – cold" and "dry – wet".
Aristotle added a fifth element, aether (αἰθήρ aither), as the quintessence, reasoning that whereas fire, earth, air, and water were earthly and corruptible, since no changes had been perceived in the heavenly regions, the stars cannot be made out of any of the four elements but must be made of a different, unchangeable, heavenly substance. It had previously been believed by pre-Socratics such as Empedocles and Anaxagoras that aether, the name applied to the material of heavenly bodies, was a form of fire. Aristotle himself did not use the term aether for the fifth element, and strongly criticised the pre-Socratics for associating the term with fire. He preferred a number of other terms indicating eternal movement, thus emphasising the evidence for his discovery of a new element. These five elements have been associated since Plato's Timaeus with the five platonic solids.
The Neoplatonic philosopher Proclus rejected Aristotle's theory relating the elements to the sensible qualities hot, cold, wet, and dry. He maintained that each of the elements has three properties. Fire is sharp, subtle, and mobile while its opposite, earth, is blunt, dense, and immobile; they are joined by the intermediate elements, air and water, in the following fashion:
A text written in Egypt in Hellenistic or Roman times called the Kore Kosmou ("Virgin of the World") ascribed to Hermes Trismegistus (associated with the Egyptian god Thoth), names the four elements fire, water, air, and earth. As described in this book:
And Isis answer made: Of living things, my son, some are made friends with fire, and some with water, some with air, and some with earth, and some with two or three of these, and some with all. And, on the contrary, again some are made enemies of fire, and some of water, some of earth, and some of air, and some of two of them, and some of three, and some of all. For instance, son, the locust and all flies flee fire; the eagle and the hawk and all high-flying birds flee water; fish, air and earth; the snake avoids the open air. Whereas snakes and all creeping things love earth; all swimming things love water; winged things, air, of which they are the citizens; while those that fly still higher love the fire and have the habitat near it. Not that some of the animals as well do not love fire; for instance salamanders, for they even have their homes in it. It is because one or another of the elements doth form their bodies’ outer envelope. Each soul, accordingly, while it is in its body is weighted and constricted by these four.
The system of five elements are found in Vedas, especially Ayurveda, the pancha mahabhuta, or "five great elements", of Hinduism are:
They further suggest that all of creation, including the human body, is made of these five essential elements and that upon death, the human body dissolves into these five elements of nature, thereby balancing the cycle of nature.
The five elements are associated with the five senses, and act as the gross medium for the experience of sensations. The basest element, earth, created using all the other elements, can be perceived by all five senses — (i) hearing, (ii) touch, (iii) sight, (iv) taste, and (v) smell. The next higher element, water, has no odor but can be heard, felt, seen and tasted. Next comes fire, which can be heard, felt and seen. Air can be heard and felt. "Akasha" (aether) is beyond the senses of smell, taste, sight, and touch; it being accessible to the sense of hearing alone.
Buddhism has had a variety of thought about the five elements and their existence and relevance, some of which continue to this day.
In the Pali literature, the mahabhuta ("great elements") or catudhatu ("four elements") are earth, water, fire and air. In early Buddhism, the four elements are a basis for understanding suffering and for liberating oneself from suffering. The earliest Buddhist texts explain that the four primary material elements are solidity, fluidity, temperature, and mobility, characterized as earth, water, fire, and air, respectively.
The Buddha's teaching regarding the four elements is to be understood as the base of all observation of real sensations rather than as a philosophy. The four properties are cohesion (water), solidity or inertia (earth), expansion or vibration (air) and heat or energy content (fire). He promulgated a categorization of mind and matter as composed of eight types of "kalapas" of which the four elements are primary and a secondary group of four are colour, smell, taste, and nutriment which are derivative from the four primaries.
Thanissaro Bhikkhu (1997) renders an extract of Shakyamuni Buddha’s from Pali into English thus:
Just as a skilled butcher or his apprentice, having killed a cow, would sit at a crossroads cutting it up into pieces, the monk contemplates this very body — however it stands, however it is disposed — in terms of properties: ‘In this body there is the earth property, the liquid property, the fire property, & the wind property.’
Tibetan Buddhist medical literature speaks of the pañca mahābhūta (five elements) or "elemental properties": earth, water, fire, wind, and space. The concept was extensively used in traditional Tibetan medicine. Tibetan Buddhist theology, tantra traditions, and "astrological texts" also spoke of them making up the "environment, [human] bodies," and at the smallest or "subtlest" level of existence, parts of thought and the mind. Also at the subtlest level of existence, the elements exist as "pure natures represented by the five female buddhas", Ākāśadhātviśvarī, Buddhalocanā, Mamakī, Pāṇḍarāvasinī, and Samayatārā, and these pure natures "manifest as the physical properties of earth (solidity), water (fluidity), fire (heat and light), wind (movement and energy), and" the expanse of space. These natures exist as all "qualities" that are in the physical world and take forms in it.
The elemental system used in medieval alchemy was developed primarily by the anonymous authors of the Arabic works attributed to Pseudo Apollonius of Tyana. This system consisted of the four classical elements of air, earth, fire, and water, in addition to a new theory called the sulphur-mercury theory of metals, which was based on two elements: sulphur, characterizing the principle of combustibility, "the stone which burns"; and mercury, characterizing the principle of metallic properties. They were seen by early alchemists as idealized expressions of irreducible components of the universe and are of larger consideration within philosophical alchemy.
The three metallic principles—sulphur to flammability or combustion, mercury to volatility and stability, and salt to solidity—became the tria prima of the Swiss alchemist Paracelsus. He reasoned that Aristotle's four element theory appeared in bodies as three principles. Paracelsus saw these principles as fundamental and justified them by recourse to the description of how wood burns in fire. Mercury included the cohesive principle, so that when it left in smoke the wood fell apart. Smoke described the volatility (the mercurial principle), the heat-giving flames described flammability (sulphur), and the remnant ash described solidity (salt).
In traditional Bakongo religion, the four elements are incorporated into the Kongo cosmogram. This sacred symbol depicts the physical world (Nseke), the spiritual world of the ancestors (Mpémba), the Kalûnga line that runs between the two worlds, the sacred river (mbûngi) that began as a circular void and forms a circle around the two worlds, and the path of the sun. Each element correlates to a period in the life cycle, which the Bakongo people also equate to the four cardinal directions and seasons. According to their cosmology, all living things go through this cycle.
Japanese traditions use a set of elements called the 五大 (godai, literally "five great"). These five are earth, water, fire, wind/air, and void. These came from Indian Vastu shastra philosophy and Buddhist beliefs; in addition, the classical Chinese elements (五行, wu xing) are also prominent in Japanese culture, especially to the influential Neo-Confucianists during the medieval Edo period.
The Islamic philosophers al-Kindi, Avicenna and Fakhr al-Din al-Razi followed Aristotle in connecting the four elements with the four natures heat and cold (the active force), and dryness and moisture (the recipients).
The medicine wheel is a sacred symbol across many Indigenous American cultures that signifies Earth's boundary and all the knowledge of the universe. It depicts the four cardinal directions, the path of the sun, the four seasons and the four sacred medicines. Each element is also represented by a color that signifies that four races of humans.
The medicine wheel symbol is a modern invention dating to approximately 1972, with these descriptions and associations being a later addition. The associations with the classical elements are not grounded in traditional Indigenous teachings and the symbol has not been adopted by all Indigenous American nations.
The Aristotelian tradition and medieval alchemy eventually gave rise to modern chemistry, scientific theories and new taxonomies. By the time of Antoine Lavoisier, for example, a list of elements would no longer refer to classical elements. Some modern scientists see a parallel between the classical elements and the four states of matter: solid, liquid, gas and weakly ionized plasma.
Modern science recognizes classes of elementary particles which have no substructure (or rather, particles that are not made of other particles) and composite particles having substructure (particles made of other particles).
Western astrology uses the four classical elements in connection with astrological charts and horoscopes. The twelve signs of the zodiac are divided into the four elements: Fire signs are Aries, Leo and Sagittarius, Earth signs are Taurus, Virgo and Capricorn, Air signs are Gemini, Libra and Aquarius, and Water signs are Cancer, Scorpio, and Pisces.
The Dutch historian of science Eduard Jan Dijksterhuis writes that the theory of the classical elements "was bound to exercise a really harmful influence. As is now clear, Aristotle, by adopting this theory as the basis of his interpretation of nature and by never losing faith in it, took a course which promised few opportunities and many dangers for science." Bertrand Russell says that Aristotle's thinking became imbued with almost biblical authority in later centuries. So much so that "Ever since the beginning of the seventeenth century, almost every serious intellectual advance has had to begin with an attack on some Aristotelian doctrine". | [
{
"paragraph_id": 0,
"text": "The classical elements typically refer to earth, water, air, fire, and (later) aether which were proposed to explain the nature and complexity of all matter in terms of simpler substances. Ancient cultures in Greece, Tibet, and India had similar lists which sometimes referred, in local languages, to \"air\" as \"wind\" and the fifth element as \"void\".",
"title": ""
},
{
"paragraph_id": 1,
"text": "These different cultures and even individual philosophers had widely varying explanations concerning their attributes and how they related to observable phenomena as well as cosmology. Sometimes these theories overlapped with mythology and were personified in deities. Some of these interpretations included atomism (the idea of very small, indivisible portions of matter), but other interpretations considered the elements to be divisible into infinitely small pieces without changing their nature.",
"title": ""
},
{
"paragraph_id": 2,
"text": "While the classification of the material world in ancient India, Hellenistic Egypt, and ancient Greece into air, earth, fire, and water was more philosophical, during the Middle Ages medieval scientists used practical, experimental observation to classify materials. In Europe, the ancient Greek concept, devised by Empedocles, evolved into the systematic classifications of Aristotle and Hippocrates. This evolved slightly into the medieval system, and eventually became the object of experimental verification in the 1600s, at the start of the Scientific Revolution.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Modern science does not support the classical elements to classify types of substances. Atomic theory classifies atoms into more than a hundred chemical elements such as oxygen, iron, and mercury, which may form chemical compounds and mixtures. The modern categories roughly corresponding to the classical elements are the states of matter produced under different temperatures and pressures. Solid, liquid, gas, and plasma share many attributes with the corresponding classical elements of earth, water, air, and fire, but these states describe the similar behavior of different types of atoms at similar energy levels, not the characteristic behavior of certain atoms or substances.",
"title": ""
},
{
"paragraph_id": 4,
"text": "",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 5,
"text": "The ancient Greek concept of four basic elements, these being earth (γῆ gê), water (ὕδωρ hýdōr), air (ἀήρ aḗr), and fire (πῦρ pŷr), dates from pre-Socratic times and persisted throughout the Middle Ages and into the Early modern period, deeply influencing European thought and culture.",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 6,
"text": "The classical elements were first proposed independently by several early Pre-Socratic philosophers. Greek philosophers had debated which substance was the arche (\"first principle\"), or primordial element from which everything else was made. Thales (c. 626/623 – c. 548/545 BC) believed that water was this principle. Anaximander (c. 610 – c. 546 BC) argued that the primordial substance was not any of the known substances, but could be transformed into them, and they into each other. Anaximenes (c. 586 – c. 526 BC) favored air, and Heraclitus (fl. c. 500 BC) championed fire.",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 7,
"text": "The Sicilian Greek philosopher Empedocles (c. 450 BC) was the first to propose the four classical elements as a set: fire, earth, air, and water. He called them the four \"roots\" (ῥιζώματα, rhizōmata). Empedocles also proved (at least to his own satisfaction) that air was a separate substance by observing that a bucket inverted in water did not become filled with water, a pocket of air remaining trapped inside.",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 8,
"text": "Fire, earth, air, and water have become the popular most popular set in modern interpretations of the classical elements. One version is provided by Robert Boyle in The Sceptical Chymist, which was published in 1661 in the form of a dialogue between five characters. Themistius, the Aristotelian of the party, says:",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 9,
"text": "If You but consider a piece of green-Wood burning in a Chimney, You will readily discern in the disbanded parts of it the four Elements, of which we teach It and other mixt bodies to be compos’d. The fire discovers it self in the flame ... the smoke by ascending to the top of the chimney, and there readily vanishing into air ... manifests to what Element it belongs and gladly returnes. The water ... boyling and hissing at the ends of the burning Wood betrayes it self ... and the ashes by their weight, their firiness, and their dryness, put it past doubt that they belong to the Element of Earth.",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 10,
"text": "According to Galen, these elements were used by Hippocrates (c. 460 – c. 370 BC) in describing the human body with an association with the four humours: yellow bile (fire), black bile (earth), blood (air), and phlegm (water). Medical care was primarily about helping the patient stay in or return to their own personal natural balanced state.",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 11,
"text": "Plato (428/423 – 348/347 BC) seems to have been the first to use the term \"element (στοιχεῖον, stoicheîon)\" in reference to air, fire, earth, and water. The ancient Greek word for element, stoicheion (from stoicheo, \"to line up\") meant \"smallest division (of a sun-dial), a syllable\", as the composing unit of an alphabet it could denote a letter and the smallest unit from which a word is formed.",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 12,
"text": "In On the Heavens (350 BC), Aristotle defines \"element\" in general:",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 13,
"text": "An element, we take it, is a body into which other bodies may be analysed, present in them potentially or in actuality (which of these, is still disputable), and not itself divisible into bodies different in form. That, or something like it, is what all men in every case mean by element.",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 14,
"text": "In his On Generation and Corruption, Aristotle related each of the four elements to two of the four sensible qualities:",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 15,
"text": "A classic diagram has one square inscribed in the other, with the corners of one being the classical elements, and the corners of the other being the properties. The opposite corner is the opposite of these properties, \"hot – cold\" and \"dry – wet\".",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 16,
"text": "Aristotle added a fifth element, aether (αἰθήρ aither), as the quintessence, reasoning that whereas fire, earth, air, and water were earthly and corruptible, since no changes had been perceived in the heavenly regions, the stars cannot be made out of any of the four elements but must be made of a different, unchangeable, heavenly substance. It had previously been believed by pre-Socratics such as Empedocles and Anaxagoras that aether, the name applied to the material of heavenly bodies, was a form of fire. Aristotle himself did not use the term aether for the fifth element, and strongly criticised the pre-Socratics for associating the term with fire. He preferred a number of other terms indicating eternal movement, thus emphasising the evidence for his discovery of a new element. These five elements have been associated since Plato's Timaeus with the five platonic solids.",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 17,
"text": "The Neoplatonic philosopher Proclus rejected Aristotle's theory relating the elements to the sensible qualities hot, cold, wet, and dry. He maintained that each of the elements has three properties. Fire is sharp, subtle, and mobile while its opposite, earth, is blunt, dense, and immobile; they are joined by the intermediate elements, air and water, in the following fashion:",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 18,
"text": "A text written in Egypt in Hellenistic or Roman times called the Kore Kosmou (\"Virgin of the World\") ascribed to Hermes Trismegistus (associated with the Egyptian god Thoth), names the four elements fire, water, air, and earth. As described in this book:",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 19,
"text": "And Isis answer made: Of living things, my son, some are made friends with fire, and some with water, some with air, and some with earth, and some with two or three of these, and some with all. And, on the contrary, again some are made enemies of fire, and some of water, some of earth, and some of air, and some of two of them, and some of three, and some of all. For instance, son, the locust and all flies flee fire; the eagle and the hawk and all high-flying birds flee water; fish, air and earth; the snake avoids the open air. Whereas snakes and all creeping things love earth; all swimming things love water; winged things, air, of which they are the citizens; while those that fly still higher love the fire and have the habitat near it. Not that some of the animals as well do not love fire; for instance salamanders, for they even have their homes in it. It is because one or another of the elements doth form their bodies’ outer envelope. Each soul, accordingly, while it is in its body is weighted and constricted by these four.",
"title": "Hellenistic philosophy"
},
{
"paragraph_id": 20,
"text": "",
"title": "Ancient Indian philosophy"
},
{
"paragraph_id": 21,
"text": "The system of five elements are found in Vedas, especially Ayurveda, the pancha mahabhuta, or \"five great elements\", of Hinduism are:",
"title": "Ancient Indian philosophy"
},
{
"paragraph_id": 22,
"text": "They further suggest that all of creation, including the human body, is made of these five essential elements and that upon death, the human body dissolves into these five elements of nature, thereby balancing the cycle of nature.",
"title": "Ancient Indian philosophy"
},
{
"paragraph_id": 23,
"text": "The five elements are associated with the five senses, and act as the gross medium for the experience of sensations. The basest element, earth, created using all the other elements, can be perceived by all five senses — (i) hearing, (ii) touch, (iii) sight, (iv) taste, and (v) smell. The next higher element, water, has no odor but can be heard, felt, seen and tasted. Next comes fire, which can be heard, felt and seen. Air can be heard and felt. \"Akasha\" (aether) is beyond the senses of smell, taste, sight, and touch; it being accessible to the sense of hearing alone.",
"title": "Ancient Indian philosophy"
},
{
"paragraph_id": 24,
"text": "",
"title": "Ancient Indian philosophy"
},
{
"paragraph_id": 25,
"text": "Buddhism has had a variety of thought about the five elements and their existence and relevance, some of which continue to this day.",
"title": "Ancient Indian philosophy"
},
{
"paragraph_id": 26,
"text": "In the Pali literature, the mahabhuta (\"great elements\") or catudhatu (\"four elements\") are earth, water, fire and air. In early Buddhism, the four elements are a basis for understanding suffering and for liberating oneself from suffering. The earliest Buddhist texts explain that the four primary material elements are solidity, fluidity, temperature, and mobility, characterized as earth, water, fire, and air, respectively.",
"title": "Ancient Indian philosophy"
},
{
"paragraph_id": 27,
"text": "The Buddha's teaching regarding the four elements is to be understood as the base of all observation of real sensations rather than as a philosophy. The four properties are cohesion (water), solidity or inertia (earth), expansion or vibration (air) and heat or energy content (fire). He promulgated a categorization of mind and matter as composed of eight types of \"kalapas\" of which the four elements are primary and a secondary group of four are colour, smell, taste, and nutriment which are derivative from the four primaries.",
"title": "Ancient Indian philosophy"
},
{
"paragraph_id": 28,
"text": "Thanissaro Bhikkhu (1997) renders an extract of Shakyamuni Buddha’s from Pali into English thus:",
"title": "Ancient Indian philosophy"
},
{
"paragraph_id": 29,
"text": "Just as a skilled butcher or his apprentice, having killed a cow, would sit at a crossroads cutting it up into pieces, the monk contemplates this very body — however it stands, however it is disposed — in terms of properties: ‘In this body there is the earth property, the liquid property, the fire property, & the wind property.’",
"title": "Ancient Indian philosophy"
},
{
"paragraph_id": 30,
"text": "Tibetan Buddhist medical literature speaks of the pañca mahābhūta (five elements) or \"elemental properties\": earth, water, fire, wind, and space. The concept was extensively used in traditional Tibetan medicine. Tibetan Buddhist theology, tantra traditions, and \"astrological texts\" also spoke of them making up the \"environment, [human] bodies,\" and at the smallest or \"subtlest\" level of existence, parts of thought and the mind. Also at the subtlest level of existence, the elements exist as \"pure natures represented by the five female buddhas\", Ākāśadhātviśvarī, Buddhalocanā, Mamakī, Pāṇḍarāvasinī, and Samayatārā, and these pure natures \"manifest as the physical properties of earth (solidity), water (fluidity), fire (heat and light), wind (movement and energy), and\" the expanse of space. These natures exist as all \"qualities\" that are in the physical world and take forms in it.",
"title": "Ancient Indian philosophy"
},
{
"paragraph_id": 31,
"text": "",
"title": "Post-classical history"
},
{
"paragraph_id": 32,
"text": "The elemental system used in medieval alchemy was developed primarily by the anonymous authors of the Arabic works attributed to Pseudo Apollonius of Tyana. This system consisted of the four classical elements of air, earth, fire, and water, in addition to a new theory called the sulphur-mercury theory of metals, which was based on two elements: sulphur, characterizing the principle of combustibility, \"the stone which burns\"; and mercury, characterizing the principle of metallic properties. They were seen by early alchemists as idealized expressions of irreducible components of the universe and are of larger consideration within philosophical alchemy.",
"title": "Post-classical history"
},
{
"paragraph_id": 33,
"text": "The three metallic principles—sulphur to flammability or combustion, mercury to volatility and stability, and salt to solidity—became the tria prima of the Swiss alchemist Paracelsus. He reasoned that Aristotle's four element theory appeared in bodies as three principles. Paracelsus saw these principles as fundamental and justified them by recourse to the description of how wood burns in fire. Mercury included the cohesive principle, so that when it left in smoke the wood fell apart. Smoke described the volatility (the mercurial principle), the heat-giving flames described flammability (sulphur), and the remnant ash described solidity (salt).",
"title": "Post-classical history"
},
{
"paragraph_id": 34,
"text": "In traditional Bakongo religion, the four elements are incorporated into the Kongo cosmogram. This sacred symbol depicts the physical world (Nseke), the spiritual world of the ancestors (Mpémba), the Kalûnga line that runs between the two worlds, the sacred river (mbûngi) that began as a circular void and forms a circle around the two worlds, and the path of the sun. Each element correlates to a period in the life cycle, which the Bakongo people also equate to the four cardinal directions and seasons. According to their cosmology, all living things go through this cycle.",
"title": "Post-classical history"
},
{
"paragraph_id": 35,
"text": "",
"title": "Post-classical history"
},
{
"paragraph_id": 36,
"text": "Japanese traditions use a set of elements called the 五大 (godai, literally \"five great\"). These five are earth, water, fire, wind/air, and void. These came from Indian Vastu shastra philosophy and Buddhist beliefs; in addition, the classical Chinese elements (五行, wu xing) are also prominent in Japanese culture, especially to the influential Neo-Confucianists during the medieval Edo period.",
"title": "Post-classical history"
},
{
"paragraph_id": 37,
"text": "The Islamic philosophers al-Kindi, Avicenna and Fakhr al-Din al-Razi followed Aristotle in connecting the four elements with the four natures heat and cold (the active force), and dryness and moisture (the recipients).",
"title": "Post-classical history"
},
{
"paragraph_id": 38,
"text": "The medicine wheel is a sacred symbol across many Indigenous American cultures that signifies Earth's boundary and all the knowledge of the universe. It depicts the four cardinal directions, the path of the sun, the four seasons and the four sacred medicines. Each element is also represented by a color that signifies that four races of humans.",
"title": "Post-classical history"
},
{
"paragraph_id": 39,
"text": "The medicine wheel symbol is a modern invention dating to approximately 1972, with these descriptions and associations being a later addition. The associations with the classical elements are not grounded in traditional Indigenous teachings and the symbol has not been adopted by all Indigenous American nations.",
"title": "Post-classical history"
},
{
"paragraph_id": 40,
"text": "",
"title": "Modern history"
},
{
"paragraph_id": 41,
"text": "The Aristotelian tradition and medieval alchemy eventually gave rise to modern chemistry, scientific theories and new taxonomies. By the time of Antoine Lavoisier, for example, a list of elements would no longer refer to classical elements. Some modern scientists see a parallel between the classical elements and the four states of matter: solid, liquid, gas and weakly ionized plasma.",
"title": "Modern history"
},
{
"paragraph_id": 42,
"text": "Modern science recognizes classes of elementary particles which have no substructure (or rather, particles that are not made of other particles) and composite particles having substructure (particles made of other particles).",
"title": "Modern history"
},
{
"paragraph_id": 43,
"text": "",
"title": "Modern history"
},
{
"paragraph_id": 44,
"text": "Western astrology uses the four classical elements in connection with astrological charts and horoscopes. The twelve signs of the zodiac are divided into the four elements: Fire signs are Aries, Leo and Sagittarius, Earth signs are Taurus, Virgo and Capricorn, Air signs are Gemini, Libra and Aquarius, and Water signs are Cancer, Scorpio, and Pisces.",
"title": "Modern history"
},
{
"paragraph_id": 45,
"text": "The Dutch historian of science Eduard Jan Dijksterhuis writes that the theory of the classical elements \"was bound to exercise a really harmful influence. As is now clear, Aristotle, by adopting this theory as the basis of his interpretation of nature and by never losing faith in it, took a course which promised few opportunities and many dangers for science.\" Bertrand Russell says that Aristotle's thinking became imbued with almost biblical authority in later centuries. So much so that \"Ever since the beginning of the seventeenth century, almost every serious intellectual advance has had to begin with an attack on some Aristotelian doctrine\".",
"title": "Modern history"
}
] | The classical elements typically refer to earth, water, air, fire, and (later) aether which were proposed to explain the nature and complexity of all matter in terms of simpler substances. Ancient cultures in Greece, Tibet, and India had similar lists which sometimes referred, in local languages, to "air" as "wind" and the fifth element as "void". These different cultures and even individual philosophers had widely varying explanations concerning their attributes and how they related to observable phenomena as well as cosmology. Sometimes these theories overlapped with mythology and were personified in deities. Some of these interpretations included atomism, but other interpretations considered the elements to be divisible into infinitely small pieces without changing their nature. While the classification of the material world in ancient India, Hellenistic Egypt, and ancient Greece into air, earth, fire, and water was more philosophical, during the Middle Ages medieval scientists used practical, experimental observation to classify materials. In Europe, the ancient Greek concept, devised by Empedocles, evolved into the systematic classifications of Aristotle and Hippocrates. This evolved slightly into the medieval system, and eventually became the object of experimental verification in the 1600s, at the start of the Scientific Revolution. Modern science does not support the classical elements to classify types of substances. Atomic theory classifies atoms into more than a hundred chemical elements such as oxygen, iron, and mercury, which may form chemical compounds and mixtures. The modern categories roughly corresponding to the classical elements are the states of matter produced under different temperatures and pressures. Solid, liquid, gas, and plasma share many attributes with the corresponding classical elements of earth, water, air, and fire, but these states describe the similar behavior of different types of atoms at similar energy levels, not the characteristic behavior of certain atoms or substances. | 2001-09-22T23:17:09Z | 2023-12-31T05:05:10Z | [
"Template:Lang",
"Template:Transliteration",
"Template:Redirect",
"Template:Citation",
"Template:Cite encyclopedia",
"Template:Authority control",
"Template:Notelist",
"Template:Portal",
"Template:Cite book",
"Template:Cite magazine",
"Template:Refend",
"Template:Blockquote",
"Template:Clear",
"Template:Efn",
"Template:Multiple image",
"Template:Reflist",
"Template:Cite AV media",
"Template:Cite journal",
"Template:Cite wikisource",
"Template:Use dmy dates",
"Template:Sfnp",
"Template:Circa",
"Template:Section link",
"Template:Refbegin",
"Template:Commons category-inline",
"Template:TOC limit",
"Template:Classic element",
"Template:IAST",
"Template:See also",
"Template:Cite SEP",
"Template:Short description",
"Template:Annotated link",
"Template:Cite web",
"Template:Use British English",
"Template:Anchor",
"Template:·",
"Template:Main",
"Template:About"
] | https://en.wikipedia.org/wiki/Classical_element |
6,314 | Fire (classical element) | Fire is one of the four classical elements along with earth, water and air in ancient Greek philosophy and science. Fire is considered to be both hot and dry and, according to Plato, is associated with the tetrahedron.
Fire is one of the four classical elements in ancient Greek philosophy and science. It was commonly associated with the qualities of energy, assertiveness, and passion. In one Greek myth, Prometheus stole fire from the gods to protect the otherwise helpless humans, but was punished for this charity.
Fire was one of many archai proposed by the pre-Socratics, most of whom sought to reduce the cosmos, or its creation, to a single substance. Heraclitus (c. 535 BCE – c. 475 BCE) considered fire to be the most fundamental of all elements. He believed fire gave rise to the other three elements: "All things are an interchange for fire, and fire for all things, just like goods for gold and gold for goods." He had a reputation for obscure philosophical principles and for speaking in riddles. He described how fire gave rise to the other elements as the: "upward-downward path", (ὁδὸς ἄνω κάτω), a "hidden harmony" or series of transformations he called the "turnings of fire", (πυρὸς τροπαὶ), first into sea, and half that sea into earth, and half that earth into rarefied air. This is a concept that anticipates both the four classical elements of Empedocles and Aristotle's transmutation of the four elements into one another.
This world, which is the same for all, no one of gods or men has made. But it always was and will be: an ever-living fire, with measures of it kindling, and measures going out.
Heraclitus regarded the soul as being a mixture of fire and water, with fire being the more noble part and water the ignoble aspect. He believed the goal of the soul is to be rid of water and become pure fire: the dry soul is the best and it is worldly pleasures that make the soul "moist". He was known as the "weeping philosopher" and died of hydropsy, a swelling due to abnormal accumulation of fluid beneath the skin.
However, Empedocles of Akragas (c. 495 – c. 435 BCE), is best known for having selected all elements as his archai and by the time of Plato (427–347 BCE), the four Empedoclian elements were well established. In the Timaeus, Plato's major cosmological dialogue, the Platonic solid he associated with fire was the tetrahedron which is formed from four triangles and contains the least volume with the greatest surface area. This also makes fire the element with the smallest number of sides, and Plato regarded it as appropriate for the heat of fire, which he felt is sharp and stabbing, (like one of the points of a tetrahedron).
Plato's student Aristotle (384–322 BCE) did not maintain his former teacher's geometric view of the elements, but rather preferred a somewhat more naturalistic explanation for the elements based on their traditional qualities. Fire the hot and dry element, like the other elements, was an abstract principle and not identical with the normal solids, liquids and combustion phenomena we experience:
What we commonly call fire. It is not really fire, for fire is an excess of heat and a sort of ebullition; but in reality, of what we call air, the part surrounding the earth is moist and warm, because it contains both vapour and a dry exhalation from the earth.
According to Aristotle, the four elements rise or fall toward their natural place in concentric layers surrounding the center of the earth and form the terrestrial or sublunary spheres.
In ancient Greek medicine, each of the four humours became associated with an element. Yellow bile was the humor identified with fire, since both were hot and dry. Other things associated with fire and yellow bile in ancient and medieval medicine included the season of summer, since it increased the qualities of heat and aridity; the choleric temperament (of a person dominated by the yellow bile humour); the masculine; and the eastern point of the compass.
In alchemy the chemical element of sulfur was often associated with fire and its alchemical symbol and its symbol was an upward-pointing triangle. In alchemic tradition, metals are incubated by fire in the womb of the Earth and alchemists only accelerate their development.
Agni is a Hindu and Vedic deity. The word agni is Sanskrit for fire (noun), cognate with Latin ignis (the root of English ignite), Russian огонь (fire), pronounced agon. Agni has three forms: fire, lightning and the sun.
Agni is one of the most important of the Vedic gods. He is the god of fire and the accepter of sacrifices. The sacrifices made to Agni go to the deities because Agni is a messenger from and to the other gods. He is ever-young, because the fire is re-lit every day, yet he is also immortal. In Indian tradition fire is also linked to Surya or the Sun and Mangala or Mars, and with the south-east direction.
Fire and the other Greek classical elements were incorporated into the Golden Dawn system. Philosophus (4=7) is the elemental grade attributed to fire; this grade is also attributed to the Qabalistic Sephirah Netzach and the planet Venus. The elemental weapon of fire is the Wand. Each of the elements has several associated spiritual beings. The archangel of fire is Michael, the angel is Aral, the ruler is Seraph, the king is Djin, and the fire elementals (following Paracelsus) are called salamanders. Fire is considered to be active; it is represented by the symbol for Leo and it is referred to the lower right point of the pentacle in the Supreme Invoking Ritual of the Pentacle. Many of these associations have since spread throughout the occult community.
Fire in tarot symbolizes conversion or passion. Many references to fire in tarot are related to the usage of fire in the practice of alchemy, in which the application of fire is a prime method of conversion, and everything that touches fire is changed, often beyond recognition. The symbol of fire was a cue pointing towards transformation, the chemical variant being the symbol delta, which is also the classical symbol for fire. Conversion symbolized can be good, for example, refining raw crudities to gold, as seen in The Devil. Conversion can also be bad, as in The Tower, symbolizing a downfall due to anger. Fire is associated with the suit of rods/wands, and as such, represents passion from inspiration. As an element, fire has mixed symbolism because it represents energy, which can be helpful when controlled, but volatile if left unchecked.
Fire is one of the five elements that appear in most Wiccan traditions influenced by the Golden Dawn system of magic, and Aleister Crowley's mysticism, which was in turn inspired by the Golden Dawn.
In freemasonry, fire is present, for example, during the ceremony of winter solstice, a symbol also of renaissance and energy. Freemasonry takes the ancient symbolic meaning of fire and recognizes its double nature: creation, light, on the one hand, and destruction and purification, on the other. | [
{
"paragraph_id": 0,
"text": "Fire is one of the four classical elements along with earth, water and air in ancient Greek philosophy and science. Fire is considered to be both hot and dry and, according to Plato, is associated with the tetrahedron.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Fire is one of the four classical elements in ancient Greek philosophy and science. It was commonly associated with the qualities of energy, assertiveness, and passion. In one Greek myth, Prometheus stole fire from the gods to protect the otherwise helpless humans, but was punished for this charity.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 2,
"text": "Fire was one of many archai proposed by the pre-Socratics, most of whom sought to reduce the cosmos, or its creation, to a single substance. Heraclitus (c. 535 BCE – c. 475 BCE) considered fire to be the most fundamental of all elements. He believed fire gave rise to the other three elements: \"All things are an interchange for fire, and fire for all things, just like goods for gold and gold for goods.\" He had a reputation for obscure philosophical principles and for speaking in riddles. He described how fire gave rise to the other elements as the: \"upward-downward path\", (ὁδὸς ἄνω κάτω), a \"hidden harmony\" or series of transformations he called the \"turnings of fire\", (πυρὸς τροπαὶ), first into sea, and half that sea into earth, and half that earth into rarefied air. This is a concept that anticipates both the four classical elements of Empedocles and Aristotle's transmutation of the four elements into one another.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 3,
"text": "This world, which is the same for all, no one of gods or men has made. But it always was and will be: an ever-living fire, with measures of it kindling, and measures going out.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 4,
"text": "Heraclitus regarded the soul as being a mixture of fire and water, with fire being the more noble part and water the ignoble aspect. He believed the goal of the soul is to be rid of water and become pure fire: the dry soul is the best and it is worldly pleasures that make the soul \"moist\". He was known as the \"weeping philosopher\" and died of hydropsy, a swelling due to abnormal accumulation of fluid beneath the skin.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 5,
"text": "However, Empedocles of Akragas (c. 495 – c. 435 BCE), is best known for having selected all elements as his archai and by the time of Plato (427–347 BCE), the four Empedoclian elements were well established. In the Timaeus, Plato's major cosmological dialogue, the Platonic solid he associated with fire was the tetrahedron which is formed from four triangles and contains the least volume with the greatest surface area. This also makes fire the element with the smallest number of sides, and Plato regarded it as appropriate for the heat of fire, which he felt is sharp and stabbing, (like one of the points of a tetrahedron).",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 6,
"text": "Plato's student Aristotle (384–322 BCE) did not maintain his former teacher's geometric view of the elements, but rather preferred a somewhat more naturalistic explanation for the elements based on their traditional qualities. Fire the hot and dry element, like the other elements, was an abstract principle and not identical with the normal solids, liquids and combustion phenomena we experience:",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 7,
"text": "What we commonly call fire. It is not really fire, for fire is an excess of heat and a sort of ebullition; but in reality, of what we call air, the part surrounding the earth is moist and warm, because it contains both vapour and a dry exhalation from the earth.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 8,
"text": "According to Aristotle, the four elements rise or fall toward their natural place in concentric layers surrounding the center of the earth and form the terrestrial or sublunary spheres.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 9,
"text": "In ancient Greek medicine, each of the four humours became associated with an element. Yellow bile was the humor identified with fire, since both were hot and dry. Other things associated with fire and yellow bile in ancient and medieval medicine included the season of summer, since it increased the qualities of heat and aridity; the choleric temperament (of a person dominated by the yellow bile humour); the masculine; and the eastern point of the compass.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 10,
"text": "In alchemy the chemical element of sulfur was often associated with fire and its alchemical symbol and its symbol was an upward-pointing triangle. In alchemic tradition, metals are incubated by fire in the womb of the Earth and alchemists only accelerate their development.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 11,
"text": "Agni is a Hindu and Vedic deity. The word agni is Sanskrit for fire (noun), cognate with Latin ignis (the root of English ignite), Russian огонь (fire), pronounced agon. Agni has three forms: fire, lightning and the sun.",
"title": "Indian tradition"
},
{
"paragraph_id": 12,
"text": "Agni is one of the most important of the Vedic gods. He is the god of fire and the accepter of sacrifices. The sacrifices made to Agni go to the deities because Agni is a messenger from and to the other gods. He is ever-young, because the fire is re-lit every day, yet he is also immortal. In Indian tradition fire is also linked to Surya or the Sun and Mangala or Mars, and with the south-east direction.",
"title": "Indian tradition"
},
{
"paragraph_id": 13,
"text": "Fire and the other Greek classical elements were incorporated into the Golden Dawn system. Philosophus (4=7) is the elemental grade attributed to fire; this grade is also attributed to the Qabalistic Sephirah Netzach and the planet Venus. The elemental weapon of fire is the Wand. Each of the elements has several associated spiritual beings. The archangel of fire is Michael, the angel is Aral, the ruler is Seraph, the king is Djin, and the fire elementals (following Paracelsus) are called salamanders. Fire is considered to be active; it is represented by the symbol for Leo and it is referred to the lower right point of the pentacle in the Supreme Invoking Ritual of the Pentacle. Many of these associations have since spread throughout the occult community.",
"title": "Ceremonial magic"
},
{
"paragraph_id": 14,
"text": "Fire in tarot symbolizes conversion or passion. Many references to fire in tarot are related to the usage of fire in the practice of alchemy, in which the application of fire is a prime method of conversion, and everything that touches fire is changed, often beyond recognition. The symbol of fire was a cue pointing towards transformation, the chemical variant being the symbol delta, which is also the classical symbol for fire. Conversion symbolized can be good, for example, refining raw crudities to gold, as seen in The Devil. Conversion can also be bad, as in The Tower, symbolizing a downfall due to anger. Fire is associated with the suit of rods/wands, and as such, represents passion from inspiration. As an element, fire has mixed symbolism because it represents energy, which can be helpful when controlled, but volatile if left unchecked.",
"title": "Tarot"
},
{
"paragraph_id": 15,
"text": "Fire is one of the five elements that appear in most Wiccan traditions influenced by the Golden Dawn system of magic, and Aleister Crowley's mysticism, which was in turn inspired by the Golden Dawn.",
"title": "Modern witchcraft"
},
{
"paragraph_id": 16,
"text": "In freemasonry, fire is present, for example, during the ceremony of winter solstice, a symbol also of renaissance and energy. Freemasonry takes the ancient symbolic meaning of fire and recognizes its double nature: creation, light, on the one hand, and destruction and purification, on the other.",
"title": "Freemasonry"
}
] | Fire is one of the four classical elements along with earth, water and air in ancient Greek philosophy and science. Fire is considered to be both hot and dry and, according to Plato, is associated with the tetrahedron. | 2001-09-09T19:42:53Z | 2023-10-08T12:28:24Z | [
"Template:Lang",
"Template:Reflist",
"Template:Cite web",
"Template:Short description",
"Template:Classic element",
"Template:Nowrap",
"Template:Main",
"Template:ISBN",
"Template:Wikicite",
"Template:Commons category"
] | https://en.wikipedia.org/wiki/Fire_(classical_element) |
6,315 | Air (classical element) | Air or Wind is one of the four classical elements along with water, earth and fire in ancient Greek philosophy and in Western alchemy.
According to Plato, it is associated with the octahedron; air is considered to be both hot and wet. The ancient Greeks used two words for air: aer meant the dim lower atmosphere, and aether meant the bright upper atmosphere above the clouds. Plato, for instance writes that "So it is with air: there is the brightest variety which we call aether, the muddiest which we call mist and darkness, and other kinds for which we have no name...." Among the early Greek Pre-Socratic philosophers, Anaximenes (mid-6th century BCE) named air as the arche. A similar belief was attributed by some ancient sources to Diogenes Apolloniates (late 5th century BCE), who also linked air with intelligence and soul (psyche), but other sources claim that his arche was a substance between air and fire. Aristophanes parodied such teachings in his play The Clouds by putting a prayer to air in the mouth of Socrates.
Air was one of many archai proposed by the Pre-socratics, most of whom tried to reduce all things to a single substance. However, Empedocles of Acragas (c. 495-c. 435 BCE) selected four archai for his four roots: air, fire, water, and earth. Ancient and modern opinions differ as to whether he identified air by the divine name Hera, Aidoneus or even Zeus. Empedocles’ roots became the four classical elements of Greek philosophy. Plato (427–347 BCE) took over the four elements of Empedocles. In the Timaeus, his major cosmological dialogue, the Platonic solid associated with air is the octahedron which is formed from eight equilateral triangles. This places air between fire and water which Plato regarded as appropriate because it is intermediate in its mobility, sharpness, and ability to penetrate. He also said of air that its minuscule components are so smooth that one can barely feel them.
Plato's student Aristotle (384–322 BCE) developed a different explanation for the elements based on pairs of qualities. The four elements were arranged concentrically around the center of the universe to form the sublunary sphere. According to Aristotle, air is both hot and wet and occupies a place between fire and water among the elemental spheres. Aristotle definitively separated air from aether. For him, aether was an unchanging, almost divine substance that was found only in the heavens, where it formed celestial spheres.
In ancient Greek medicine, each of the four humours became associated with an element. Blood was the humor identified with air, since both were hot and wet. Other things associated with air and blood in ancient and medieval medicine included the season of spring, since it increased the qualities of heat and moisture; the sanguine temperament (of a person dominated by the blood humour); hermaphrodite (combining the masculine quality of heat with the feminine quality of moisture); and the northern point of the compass.
The alchemical symbol for air is an upward-pointing triangle, bisected by a horizontal line.
The Hermetic Order of the Golden Dawn, founded in 1888, incorporates air and the other Greek classical elements into its teachings. The elemental weapon of air is the dagger which must be painted yellow with magical names and sigils written upon it in violet. Each of the elements has several associated spiritual beings. The archangel of air is Raphael, the angel is Chassan, the ruler is Ariel, the king is Paralda, and the air elementals (following Paracelsus) are called sylphs. Air is considerable and it is referred to the upper left point of the pentagram in the Supreme Invoking Ritual of the Pentagram. Many of these associations have since spread throughout the occult community.
In the Golden Dawn and many other magical systems, each element is associated with one of the cardinal points and is placed under the care of guardian Watchtowers. The Watchtowers derive from the Enochian system of magic founded by Dee. In the Golden Dawn, they are represented by the Enochian elemental tablets. Air is associated with the east, which is guarded by the First Watchtower.
Air is one of the five elements that appear in most Wiccan and Pagan traditions. Wicca in particular was influenced by the Golden Dawn system of magic and Aleister Crowley's mysticism.
Air is not one of the traditional five Chinese classical elements. Nevertheless, the ancient Chinese concept of Qi or chi is believed to be close to that of air. Qi is believed to be part of every living thing that exists, as a kind of "life force" or "spiritual energy". It is frequently translated as "energy flow", or literally as "air" or "breath". (For example, tiānqì, literally "sky breath", is the Chinese word for "weather"). The concept of qi is often reified, however no scientific evidence supports its existence.
The element air also appears as a concept in the Buddhist philosophy which has an ancient history in China.
Some Western modern occultists equate the Chinese classical element of metal with air, others with wood due to the elemental association of wind and wood in the bagua.
Enlil was the god of air in ancient Sumer. Shu was the ancient Egyptian deity of air and the husband of Tefnut, goddess of moisture. He became an emblem of strength by virtue of his role in separating Nut from Geb. Shu played a primary role in the Coffin Texts, which were spells intended to help the deceased reach the realm of the afterlife safely. On the way to the sky, the spirit had to travel through the air as one spell indicates: "I have gone up in Shu, I have climbed on the sunbeams." | [
{
"paragraph_id": 0,
"text": "Air or Wind is one of the four classical elements along with water, earth and fire in ancient Greek philosophy and in Western alchemy.",
"title": ""
},
{
"paragraph_id": 1,
"text": "According to Plato, it is associated with the octahedron; air is considered to be both hot and wet. The ancient Greeks used two words for air: aer meant the dim lower atmosphere, and aether meant the bright upper atmosphere above the clouds. Plato, for instance writes that \"So it is with air: there is the brightest variety which we call aether, the muddiest which we call mist and darkness, and other kinds for which we have no name....\" Among the early Greek Pre-Socratic philosophers, Anaximenes (mid-6th century BCE) named air as the arche. A similar belief was attributed by some ancient sources to Diogenes Apolloniates (late 5th century BCE), who also linked air with intelligence and soul (psyche), but other sources claim that his arche was a substance between air and fire. Aristophanes parodied such teachings in his play The Clouds by putting a prayer to air in the mouth of Socrates.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 2,
"text": "Air was one of many archai proposed by the Pre-socratics, most of whom tried to reduce all things to a single substance. However, Empedocles of Acragas (c. 495-c. 435 BCE) selected four archai for his four roots: air, fire, water, and earth. Ancient and modern opinions differ as to whether he identified air by the divine name Hera, Aidoneus or even Zeus. Empedocles’ roots became the four classical elements of Greek philosophy. Plato (427–347 BCE) took over the four elements of Empedocles. In the Timaeus, his major cosmological dialogue, the Platonic solid associated with air is the octahedron which is formed from eight equilateral triangles. This places air between fire and water which Plato regarded as appropriate because it is intermediate in its mobility, sharpness, and ability to penetrate. He also said of air that its minuscule components are so smooth that one can barely feel them.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 3,
"text": "Plato's student Aristotle (384–322 BCE) developed a different explanation for the elements based on pairs of qualities. The four elements were arranged concentrically around the center of the universe to form the sublunary sphere. According to Aristotle, air is both hot and wet and occupies a place between fire and water among the elemental spheres. Aristotle definitively separated air from aether. For him, aether was an unchanging, almost divine substance that was found only in the heavens, where it formed celestial spheres.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 4,
"text": "In ancient Greek medicine, each of the four humours became associated with an element. Blood was the humor identified with air, since both were hot and wet. Other things associated with air and blood in ancient and medieval medicine included the season of spring, since it increased the qualities of heat and moisture; the sanguine temperament (of a person dominated by the blood humour); hermaphrodite (combining the masculine quality of heat with the feminine quality of moisture); and the northern point of the compass.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 5,
"text": "The alchemical symbol for air is an upward-pointing triangle, bisected by a horizontal line.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 6,
"text": "The Hermetic Order of the Golden Dawn, founded in 1888, incorporates air and the other Greek classical elements into its teachings. The elemental weapon of air is the dagger which must be painted yellow with magical names and sigils written upon it in violet. Each of the elements has several associated spiritual beings. The archangel of air is Raphael, the angel is Chassan, the ruler is Ariel, the king is Paralda, and the air elementals (following Paracelsus) are called sylphs. Air is considerable and it is referred to the upper left point of the pentagram in the Supreme Invoking Ritual of the Pentagram. Many of these associations have since spread throughout the occult community.",
"title": "Modern reception"
},
{
"paragraph_id": 7,
"text": "In the Golden Dawn and many other magical systems, each element is associated with one of the cardinal points and is placed under the care of guardian Watchtowers. The Watchtowers derive from the Enochian system of magic founded by Dee. In the Golden Dawn, they are represented by the Enochian elemental tablets. Air is associated with the east, which is guarded by the First Watchtower.",
"title": "Modern reception"
},
{
"paragraph_id": 8,
"text": "Air is one of the five elements that appear in most Wiccan and Pagan traditions. Wicca in particular was influenced by the Golden Dawn system of magic and Aleister Crowley's mysticism.",
"title": "Modern reception"
},
{
"paragraph_id": 9,
"text": "Air is not one of the traditional five Chinese classical elements. Nevertheless, the ancient Chinese concept of Qi or chi is believed to be close to that of air. Qi is believed to be part of every living thing that exists, as a kind of \"life force\" or \"spiritual energy\". It is frequently translated as \"energy flow\", or literally as \"air\" or \"breath\". (For example, tiānqì, literally \"sky breath\", is the Chinese word for \"weather\"). The concept of qi is often reified, however no scientific evidence supports its existence.",
"title": "Parallels in non-Western traditions"
},
{
"paragraph_id": 10,
"text": "The element air also appears as a concept in the Buddhist philosophy which has an ancient history in China.",
"title": "Parallels in non-Western traditions"
},
{
"paragraph_id": 11,
"text": "Some Western modern occultists equate the Chinese classical element of metal with air, others with wood due to the elemental association of wind and wood in the bagua.",
"title": "Parallels in non-Western traditions"
},
{
"paragraph_id": 12,
"text": "Enlil was the god of air in ancient Sumer. Shu was the ancient Egyptian deity of air and the husband of Tefnut, goddess of moisture. He became an emblem of strength by virtue of his role in separating Nut from Geb. Shu played a primary role in the Coffin Texts, which were spells intended to help the deceased reach the realm of the afterlife safely. On the way to the sky, the spirit had to travel through the air as one spell indicates: \"I have gone up in Shu, I have climbed on the sunbeams.\"",
"title": "Parallels in non-Western traditions"
}
] | Air or Wind is one of the four classical elements along with water, earth and fire in ancient Greek philosophy and in Western alchemy. | 2001-09-09T19:43:39Z | 2023-09-10T23:17:28Z | [
"Template:Classic element",
"Template:Reflist",
"Template:Wikiquote",
"Template:Short description"
] | https://en.wikipedia.org/wiki/Air_(classical_element) |
6,316 | Water (classical element) | Water is one of the classical elements in ancient Greek philosophy along with air, earth and fire, in the Asian Indian system Panchamahabhuta, and in the Chinese cosmological and physiological system Wu Xing. In contemporary esoteric traditions, it is commonly associated with the qualities of emotion and intuition.
Water was one of many archai proposed by the Pre-socratics, most of whom tried to reduce all things to a single substance. However, Empedocles of Acragas (c. 495 – c. 435 BC) selected four archai for his four roots: air, fire, water and earth. Empedocles roots became the four classical elements of Greek philosophy. Plato (427–347 BC) took over the four elements of Empedocles. In the Timaeus, his major cosmological dialogue, the Platonic solid associated with water is the icosahedron which is formed from twenty equilateral triangles. This makes water the element with the greatest number of sides, which Plato regarded as appropriate because water flows out of one's hand when picked up, as if it is made of tiny little balls.
Plato's student Aristotle (384–322 BC) developed a different explanation for the elements based on pairs of qualities. The four elements were arranged concentrically around the center of the Universe to form the sublunary sphere. According to Aristotle, water is both cold and wet and occupies a place between air and earth among the elemental spheres.
In ancient Greek medicine, each of the four humours became associated with an element. Phlegm was the humor identified with water, since both were cold and wet. Other things associated with water and phlegm in ancient and medieval medicine included the season of Winter, since it increased the qualities of cold and moisture, the phlegmatic temperament, the feminine and the western point of the compass.
In alchemy, the chemical element of mercury was often associated with water and its alchemical symbol was a downward-pointing triangle.
Ap (áp-) is the Vedic Sanskrit term for water, in Classical Sanskrit occurring only in the plural is not an element.v, āpas (sometimes re-analysed as a thematic singular, āpa-), whence Hindi āp. The term is from PIE hxap water.
In Hindu philosophy, the term refers to water as an element, one of the Panchamahabhuta, or "five great elements". In Hinduism, it is also the name of the deva, a personification of water, (one of the Vasus in most later Puranic lists). The element water is also associated with Chandra or the moon and Shukra, who represent feelings, intuition and imagination.
Water and the other Greek classical elements were incorporated into the Golden Dawn system. The elemental weapon of water is the cup. Each of the elements has several associated spiritual beings. The archangel of water is Gabriel, the angel is Taliahad, the ruler is Tharsis, the king is Nichsa and the water elementals are called Ondines. It is referred to the upper right point of the pentagram in the Supreme Invoking Ritual of the Pentagram. Many of these associations have since spread throughout the occult community.
Water is one of the five elements that appear in most Wiccan traditions. Wicca in particular was influenced by the Golden Dawn system of magic and Aleister Crowley's mysticism, which was in turn inspired by the Golden Dawn. | [
{
"paragraph_id": 0,
"text": "Water is one of the classical elements in ancient Greek philosophy along with air, earth and fire, in the Asian Indian system Panchamahabhuta, and in the Chinese cosmological and physiological system Wu Xing. In contemporary esoteric traditions, it is commonly associated with the qualities of emotion and intuition.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Water was one of many archai proposed by the Pre-socratics, most of whom tried to reduce all things to a single substance. However, Empedocles of Acragas (c. 495 – c. 435 BC) selected four archai for his four roots: air, fire, water and earth. Empedocles roots became the four classical elements of Greek philosophy. Plato (427–347 BC) took over the four elements of Empedocles. In the Timaeus, his major cosmological dialogue, the Platonic solid associated with water is the icosahedron which is formed from twenty equilateral triangles. This makes water the element with the greatest number of sides, which Plato regarded as appropriate because water flows out of one's hand when picked up, as if it is made of tiny little balls.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 2,
"text": "Plato's student Aristotle (384–322 BC) developed a different explanation for the elements based on pairs of qualities. The four elements were arranged concentrically around the center of the Universe to form the sublunary sphere. According to Aristotle, water is both cold and wet and occupies a place between air and earth among the elemental spheres.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 3,
"text": "In ancient Greek medicine, each of the four humours became associated with an element. Phlegm was the humor identified with water, since both were cold and wet. Other things associated with water and phlegm in ancient and medieval medicine included the season of Winter, since it increased the qualities of cold and moisture, the phlegmatic temperament, the feminine and the western point of the compass.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 4,
"text": "In alchemy, the chemical element of mercury was often associated with water and its alchemical symbol was a downward-pointing triangle.",
"title": "Greek and Roman tradition"
},
{
"paragraph_id": 5,
"text": "Ap (áp-) is the Vedic Sanskrit term for water, in Classical Sanskrit occurring only in the plural is not an element.v, āpas (sometimes re-analysed as a thematic singular, āpa-), whence Hindi āp. The term is from PIE hxap water.",
"title": "Indian tradition"
},
{
"paragraph_id": 6,
"text": "In Hindu philosophy, the term refers to water as an element, one of the Panchamahabhuta, or \"five great elements\". In Hinduism, it is also the name of the deva, a personification of water, (one of the Vasus in most later Puranic lists). The element water is also associated with Chandra or the moon and Shukra, who represent feelings, intuition and imagination.",
"title": "Indian tradition"
},
{
"paragraph_id": 7,
"text": "Water and the other Greek classical elements were incorporated into the Golden Dawn system. The elemental weapon of water is the cup. Each of the elements has several associated spiritual beings. The archangel of water is Gabriel, the angel is Taliahad, the ruler is Tharsis, the king is Nichsa and the water elementals are called Ondines. It is referred to the upper right point of the pentagram in the Supreme Invoking Ritual of the Pentagram. Many of these associations have since spread throughout the occult community.",
"title": "Ceremonial magic"
},
{
"paragraph_id": 8,
"text": "Water is one of the five elements that appear in most Wiccan traditions. Wicca in particular was influenced by the Golden Dawn system of magic and Aleister Crowley's mysticism, which was in turn inspired by the Golden Dawn.",
"title": "Modern witchcraft"
}
] | Water is one of the classical elements in ancient Greek philosophy along with air, earth and fire, in the Asian Indian system Panchamahabhuta, and in the Chinese cosmological and physiological system Wu Xing. In contemporary esoteric traditions, it is commonly associated with the qualities of emotion and intuition. | 2023-07-06T05:47:56Z | [
"Template:Main",
"Template:IAST",
"Template:Reflist",
"Template:Short description",
"Template:Classic element"
] | https://en.wikipedia.org/wiki/Water_(classical_element) |
|
6,317 | Earth (classical element) | Earth is one of the classical elements, in some systems being one of the four along with air, fire, and water.
Earth is one of the four classical elements in ancient Greek philosophy and science. It was commonly associated with qualities of heaviness, matter and the terrestrial world. Due to the hero cults, and chthonic underworld deities, the element of earth is also associated with the sensual aspects of both life and death in later occultism.
Empedocles of Acragas (c. 495 – c. 435 BCE) proposed four archai by which to understand the cosmos: fire, air, water, and earth. Plato (427–347 BCE) believed the elements were geometric forms (the platonic solids) and he assigned the cube to the element of earth in his dialogue Timaeus. Aristotle (384–322 BCE) believed earth was the heaviest element, and his theory of natural place suggested that any earth–laden substances, would fall quickly, straight down, towards the center of the cosmos.
In Classical Greek and Roman myth, various goddesses represented the Earth, seasons, crops and fertility, including Demeter and Persephone; Ceres; the Horae (goddesses of the seasons), and Proserpina; and Hades (Pluto) who ruled the souls of dead in the Underworld.
In ancient Greek medicine, each of the four humours became associated with an element. Black bile was the humor identified with earth, since both were cold and dry. Other things associated with earth and black bile in ancient and medieval medicine included the season of fall, since it increased the qualities of cold and aridity; the melancholic temperament (of a person dominated by the black bile humour); the feminine; and the southern point of the compass.
In alchemy, earth was believed to be primarily dry, and secondarily cold, (as per Aristotle). Beyond those classical attributes, the chemical substance salt, was associated with earth and its alchemical symbol was a downward-pointing triangle, bisected by a horizontal line.
Prithvi (Sanskrit: pṛthvī, also pṛthivī) is the Hindu earth and mother goddess. According to one such tradition, she is the personification of the Earth itself; according to another, its actual mother, being Prithvi Tattwa, the essence of the element earth.
As Prithvi Mata, or "Mother Earth", she contrasts with Dyaus Pita, "father sky". In the Rigveda, earth and sky are frequently addressed as a duality, often indicated by the idea of two complementary "half-shells." In addition, the element Earth is associated with Budha or Mercury who represents communication, business, mathematics and other practical matters.
Earth and the other Greek classical elements were incorporated into the Golden Dawn system. Zelator is the elemental grade attributed to earth; this grade is also attributed to the Sephirot of Malkuth. The elemental weapon of earth is the Pentacle. Each of the elements has several associated spiritual beings. The archangel of earth is Uriel, the angel is Phorlakh, the ruler is Kerub, the king is Ghob, and the earth elementals (following Paracelsus) are called gnomes. Earth is considered to be passive; it is represented by the symbol for Taurus, and it is referred to the lower left point of the pentagram in the Supreme Invoking Ritual of the Pentagram. Many of these associations have since spread throughout the occult community.
It is sometimes represented by its Tattva or by a downward pointing triangle with a horizontal line through it.
Earth is one of the five elements that appear in most Wiccan and Pagan traditions. Wicca in particular was influenced by the Golden Dawn system of magic, and Aleister Crowley's mysticism which was in turn inspired by the Golden Dawn.
Earth is represented in the Aztec religion by a house; to the Hindus, a lotus; to the Scythians, a plough; to the Greeks, a wheel; and in Christian iconography; bulls and birds. | [
{
"paragraph_id": 0,
"text": "Earth is one of the classical elements, in some systems being one of the four along with air, fire, and water.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Earth is one of the four classical elements in ancient Greek philosophy and science. It was commonly associated with qualities of heaviness, matter and the terrestrial world. Due to the hero cults, and chthonic underworld deities, the element of earth is also associated with the sensual aspects of both life and death in later occultism.",
"title": "European tradition"
},
{
"paragraph_id": 2,
"text": "Empedocles of Acragas (c. 495 – c. 435 BCE) proposed four archai by which to understand the cosmos: fire, air, water, and earth. Plato (427–347 BCE) believed the elements were geometric forms (the platonic solids) and he assigned the cube to the element of earth in his dialogue Timaeus. Aristotle (384–322 BCE) believed earth was the heaviest element, and his theory of natural place suggested that any earth–laden substances, would fall quickly, straight down, towards the center of the cosmos.",
"title": "European tradition"
},
{
"paragraph_id": 3,
"text": "In Classical Greek and Roman myth, various goddesses represented the Earth, seasons, crops and fertility, including Demeter and Persephone; Ceres; the Horae (goddesses of the seasons), and Proserpina; and Hades (Pluto) who ruled the souls of dead in the Underworld.",
"title": "European tradition"
},
{
"paragraph_id": 4,
"text": "In ancient Greek medicine, each of the four humours became associated with an element. Black bile was the humor identified with earth, since both were cold and dry. Other things associated with earth and black bile in ancient and medieval medicine included the season of fall, since it increased the qualities of cold and aridity; the melancholic temperament (of a person dominated by the black bile humour); the feminine; and the southern point of the compass.",
"title": "European tradition"
},
{
"paragraph_id": 5,
"text": "In alchemy, earth was believed to be primarily dry, and secondarily cold, (as per Aristotle). Beyond those classical attributes, the chemical substance salt, was associated with earth and its alchemical symbol was a downward-pointing triangle, bisected by a horizontal line.",
"title": "European tradition"
},
{
"paragraph_id": 6,
"text": "Prithvi (Sanskrit: pṛthvī, also pṛthivī) is the Hindu earth and mother goddess. According to one such tradition, she is the personification of the Earth itself; according to another, its actual mother, being Prithvi Tattwa, the essence of the element earth.",
"title": "Indian tradition"
},
{
"paragraph_id": 7,
"text": "As Prithvi Mata, or \"Mother Earth\", she contrasts with Dyaus Pita, \"father sky\". In the Rigveda, earth and sky are frequently addressed as a duality, often indicated by the idea of two complementary \"half-shells.\" In addition, the element Earth is associated with Budha or Mercury who represents communication, business, mathematics and other practical matters.",
"title": "Indian tradition"
},
{
"paragraph_id": 8,
"text": "Earth and the other Greek classical elements were incorporated into the Golden Dawn system. Zelator is the elemental grade attributed to earth; this grade is also attributed to the Sephirot of Malkuth. The elemental weapon of earth is the Pentacle. Each of the elements has several associated spiritual beings. The archangel of earth is Uriel, the angel is Phorlakh, the ruler is Kerub, the king is Ghob, and the earth elementals (following Paracelsus) are called gnomes. Earth is considered to be passive; it is represented by the symbol for Taurus, and it is referred to the lower left point of the pentagram in the Supreme Invoking Ritual of the Pentagram. Many of these associations have since spread throughout the occult community.",
"title": "Ceremonial magic"
},
{
"paragraph_id": 9,
"text": "It is sometimes represented by its Tattva or by a downward pointing triangle with a horizontal line through it.",
"title": "Ceremonial magic"
},
{
"paragraph_id": 10,
"text": "Earth is one of the five elements that appear in most Wiccan and Pagan traditions. Wicca in particular was influenced by the Golden Dawn system of magic, and Aleister Crowley's mysticism which was in turn inspired by the Golden Dawn.",
"title": "Modern witchcraft"
},
{
"paragraph_id": 11,
"text": "Earth is represented in the Aztec religion by a house; to the Hindus, a lotus; to the Scythians, a plough; to the Greeks, a wheel; and in Christian iconography; bulls and birds.",
"title": "Other traditions"
}
] | Earth is one of the classical elements, in some systems being one of the four along with air, fire, and water. | 2001-09-09T19:45:14Z | 2023-09-23T20:04:17Z | [
"Template:IAST",
"Template:Reflist",
"Template:Cite web",
"Template:Wikiquote",
"Template:Short description",
"Template:Classic element",
"Template:Nowrap",
"Template:Main"
] | https://en.wikipedia.org/wiki/Earth_(classical_element) |
6,319 | Blue Jam | Blue Jam was an ambient, surreal dark comedy and horror radio programme created and directed by Chris Morris. It was broadcast on BBC Radio 1 in the early hours of the morning, for three series from 1997 to 1999.
The programme gained cult status due to its unique mix of surreal monologue, ambient soundtrack, synthesised voices, heavily edited broadcasts and recurring sketches. It featured vocal performances of Kevin Eldon, Julia Davis, Mark Heap, David Cann and Amelia Bullmore, with Morris himself delivering disturbing monologues, one of which was revamped and made into the BAFTA-winning short film My Wrongs #8245–8249 & 117. Writers who contributed to the programme included Graham Linehan, Arthur Mathews, Peter Baynham, David Quantick, Jane Bussmann, Robert Katz and the cast.
The programme was adapted into the TV series Jam, which aired in 2000. All episodes of Blue Jam are currently available for streaming and download on the Internet Archive and Youtube.
On his inspiration for making the show, Morris commented: "It was so singular, and it came from a mood, quite a desolate mood. I had this misty, autumnal, boggy mood anyway, so I just went with that. But no doubt getting to the end of something like Brass Eye, where you've been forced to be a sort of surrogate lawyer, well, that's the most creatively stifling thing you could possibly do." Morris also described the show as being "like the nightmares you have when you fall asleep listening to the BBC World Service" (a reference to the World Service also appears in one of the monologues read by Morris).
Morris originally requested that the show be broadcast at 3 a.m. on Radio 1 "because at that hour, on insomniac radio, the amplitude of terrible things is enormously overblown". As a compromise, the show was broadcast at midnight without much promotion. Morris reportedly included sketches too graphic or transgressive for radio that he knew would be cut so as to make his other material seem less transgressive in comparison. During the airing of episode 6 of series one, a re-editing of the Archbishop of Canterbury's speech at Princess Diana's funeral was deemed too offensive for broadcast, and was switched with a different episode as it aired.
Each episode opened (and closed) with a short spoken monologue (delivered by Morris) describing, in surreal, broken language, various bizarre feelings and situations (for example: "when you sick so sad you cry, and in crying cry a whole leopard from your eye"), set to ambient music interspersed with short clips of other songs and sounds. The introduction would always end with "welcome in Blue Jam", inviting the listener, who is presumably experiencing such feelings, to get lost in the program. (This format was replicated in the television adaptation Jam, often reusing opening monologues from series 3 of the radio series.) The sketches within dealt with heavy and taboo topics, such as murder, suicide, missing or dead children, and rape.
The sketches not listed are often in the style of a documentary; characters speak as if being interviewed about a recent event. In one sketch, a character voiced by Morris describes a man attempting to commit suicide by jumping off a second-story balcony repeatedly; in another, an angry man (Eldon) shouts about how his car, after being picked up from the garage, is only four feet long.
Morris included a series of 'radio stings', bizarre sequences of sounds and prose as a parody of modern DJs' own soundbites and self-advertising pieces. Each one revolves around a contemporary DJ, such as Chris Moyles, Jo Whiley and Mark Goodier, typically involving each DJ dying in a graphic way or going mad in some form – for example, Chris Moyles covering himself in jam and hanging himself from the top of a building.
Three series were produced, with a total of eighteen episodes. All episodes were originally broadcast weekly on BBC Radio 1. Series 1 was broadcast from 14 November to 19 December 1997; series 2 was broadcast from 27 March to 1 May 1998; and series 3 broadcast from 21 January to 25 February 1999.
The first five episodes of series 1 of Blue Jam were repeated by BBC Radio 4 Extra in February and March 2014, and series 2 was rebroadcast in December.
Blue Jam features songs, generally of a downtempo nature, interspersed between (and sometimes during) sketches. Artists featured includes Massive Attack, Air, Morcheeba, The Chemical Brothers, Björk, Aphex Twin, Everything But the Girl and Dimitri from Paris, as well as various non-electronic artists including Sly and the Family Stone, Serge Gainsbourg, The Cardigans and Eels.
Blue Jam was favourably reviewed on several occasions by The Guardian and also received a positive review by The Independent.
Digital Spy wrote in 2014: "It's a heady cocktail that provokes an odd, unsettling reaction in the listener, yet Blue Jam is still thumpingly and frequently laugh-out-loud hilarious." Hot Press called it "as odd as comedy gets".
A CD of a number of Blue Jam sketches was released on 23 October 2000 by record label Warp. Although the CD claims to have 22 tracks, the last one, "www.bishopslips.com", is not a track, but rather a reference to the "Bishopslips" sketch, which was cut in the middle of a broadcast. Most of the sketches on the CD were remade for Jam.
Blue Jam was later made for television and broadcast on Channel 4 as Jam. It used unusual editing techniques to achieve an unnerving ambience in keeping with the radio show. Many of the sketches were lifted from the radio version, even to the extent of simply setting images to the radio soundtrack. A subsequent "re-mixed" airing, called Jaaaaam was even more extreme in its use of post-production gadgetry, often heavily distorting the footage.
Blue Jam shares parallels with early editions of a US public radio show Joe Frank: Work in Progress from the mid-1980s, that Joe Frank did on the NPR affiliate station, KCRW, in Santa Monica, California. | [
{
"paragraph_id": 0,
"text": "Blue Jam was an ambient, surreal dark comedy and horror radio programme created and directed by Chris Morris. It was broadcast on BBC Radio 1 in the early hours of the morning, for three series from 1997 to 1999.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The programme gained cult status due to its unique mix of surreal monologue, ambient soundtrack, synthesised voices, heavily edited broadcasts and recurring sketches. It featured vocal performances of Kevin Eldon, Julia Davis, Mark Heap, David Cann and Amelia Bullmore, with Morris himself delivering disturbing monologues, one of which was revamped and made into the BAFTA-winning short film My Wrongs #8245–8249 & 117. Writers who contributed to the programme included Graham Linehan, Arthur Mathews, Peter Baynham, David Quantick, Jane Bussmann, Robert Katz and the cast.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The programme was adapted into the TV series Jam, which aired in 2000. All episodes of Blue Jam are currently available for streaming and download on the Internet Archive and Youtube.",
"title": ""
},
{
"paragraph_id": 3,
"text": "On his inspiration for making the show, Morris commented: \"It was so singular, and it came from a mood, quite a desolate mood. I had this misty, autumnal, boggy mood anyway, so I just went with that. But no doubt getting to the end of something like Brass Eye, where you've been forced to be a sort of surrogate lawyer, well, that's the most creatively stifling thing you could possibly do.\" Morris also described the show as being \"like the nightmares you have when you fall asleep listening to the BBC World Service\" (a reference to the World Service also appears in one of the monologues read by Morris).",
"title": "Production"
},
{
"paragraph_id": 4,
"text": "Morris originally requested that the show be broadcast at 3 a.m. on Radio 1 \"because at that hour, on insomniac radio, the amplitude of terrible things is enormously overblown\". As a compromise, the show was broadcast at midnight without much promotion. Morris reportedly included sketches too graphic or transgressive for radio that he knew would be cut so as to make his other material seem less transgressive in comparison. During the airing of episode 6 of series one, a re-editing of the Archbishop of Canterbury's speech at Princess Diana's funeral was deemed too offensive for broadcast, and was switched with a different episode as it aired.",
"title": "Production"
},
{
"paragraph_id": 5,
"text": "Each episode opened (and closed) with a short spoken monologue (delivered by Morris) describing, in surreal, broken language, various bizarre feelings and situations (for example: \"when you sick so sad you cry, and in crying cry a whole leopard from your eye\"), set to ambient music interspersed with short clips of other songs and sounds. The introduction would always end with \"welcome in Blue Jam\", inviting the listener, who is presumably experiencing such feelings, to get lost in the program. (This format was replicated in the television adaptation Jam, often reusing opening monologues from series 3 of the radio series.) The sketches within dealt with heavy and taboo topics, such as murder, suicide, missing or dead children, and rape.",
"title": "Format and style"
},
{
"paragraph_id": 6,
"text": "The sketches not listed are often in the style of a documentary; characters speak as if being interviewed about a recent event. In one sketch, a character voiced by Morris describes a man attempting to commit suicide by jumping off a second-story balcony repeatedly; in another, an angry man (Eldon) shouts about how his car, after being picked up from the garage, is only four feet long.",
"title": "Format and style"
},
{
"paragraph_id": 7,
"text": "Morris included a series of 'radio stings', bizarre sequences of sounds and prose as a parody of modern DJs' own soundbites and self-advertising pieces. Each one revolves around a contemporary DJ, such as Chris Moyles, Jo Whiley and Mark Goodier, typically involving each DJ dying in a graphic way or going mad in some form – for example, Chris Moyles covering himself in jam and hanging himself from the top of a building.",
"title": "Format and style"
},
{
"paragraph_id": 8,
"text": "Three series were produced, with a total of eighteen episodes. All episodes were originally broadcast weekly on BBC Radio 1. Series 1 was broadcast from 14 November to 19 December 1997; series 2 was broadcast from 27 March to 1 May 1998; and series 3 broadcast from 21 January to 25 February 1999.",
"title": "Episodes"
},
{
"paragraph_id": 9,
"text": "The first five episodes of series 1 of Blue Jam were repeated by BBC Radio 4 Extra in February and March 2014, and series 2 was rebroadcast in December.",
"title": "Episodes"
},
{
"paragraph_id": 10,
"text": "Blue Jam features songs, generally of a downtempo nature, interspersed between (and sometimes during) sketches. Artists featured includes Massive Attack, Air, Morcheeba, The Chemical Brothers, Björk, Aphex Twin, Everything But the Girl and Dimitri from Paris, as well as various non-electronic artists including Sly and the Family Stone, Serge Gainsbourg, The Cardigans and Eels.",
"title": "Music"
},
{
"paragraph_id": 11,
"text": "Blue Jam was favourably reviewed on several occasions by The Guardian and also received a positive review by The Independent.",
"title": "Reception"
},
{
"paragraph_id": 12,
"text": "Digital Spy wrote in 2014: \"It's a heady cocktail that provokes an odd, unsettling reaction in the listener, yet Blue Jam is still thumpingly and frequently laugh-out-loud hilarious.\" Hot Press called it \"as odd as comedy gets\".",
"title": "Reception"
},
{
"paragraph_id": 13,
"text": "A CD of a number of Blue Jam sketches was released on 23 October 2000 by record label Warp. Although the CD claims to have 22 tracks, the last one, \"www.bishopslips.com\", is not a track, but rather a reference to the \"Bishopslips\" sketch, which was cut in the middle of a broadcast. Most of the sketches on the CD were remade for Jam.",
"title": "CD release"
},
{
"paragraph_id": 14,
"text": "Blue Jam was later made for television and broadcast on Channel 4 as Jam. It used unusual editing techniques to achieve an unnerving ambience in keeping with the radio show. Many of the sketches were lifted from the radio version, even to the extent of simply setting images to the radio soundtrack. A subsequent \"re-mixed\" airing, called Jaaaaam was even more extreme in its use of post-production gadgetry, often heavily distorting the footage.",
"title": "Related shows"
},
{
"paragraph_id": 15,
"text": "Blue Jam shares parallels with early editions of a US public radio show Joe Frank: Work in Progress from the mid-1980s, that Joe Frank did on the NPR affiliate station, KCRW, in Santa Monica, California.",
"title": "Related shows"
}
] | Blue Jam was an ambient, surreal dark comedy and horror radio programme created and directed by Chris Morris. It was broadcast on BBC Radio 1 in the early hours of the morning, for three series from 1997 to 1999. The programme gained cult status due to its unique mix of surreal monologue, ambient soundtrack, synthesised voices, heavily edited broadcasts and recurring sketches. It featured vocal performances of Kevin Eldon, Julia Davis, Mark Heap, David Cann and Amelia Bullmore, with Morris himself delivering disturbing monologues, one of which was revamped and made into the BAFTA-winning short film My Wrongs #8245–8249 & 117. Writers who contributed to the programme included Graham Linehan, Arthur Mathews, Peter Baynham, David Quantick, Jane Bussmann, Robert Katz and the cast. The programme was adapted into the TV series Jam, which aired in 2000. All episodes of Blue Jam are currently available for streaming and download on the Internet Archive and Youtube. | 2001-09-10T20:50:59Z | 2023-12-31T22:59:25Z | [
"Template:Episode table",
"Template:Reflist",
"Template:Internet Archive",
"Template:BBC programme",
"Template:Christopher Morris",
"Template:Italic title",
"Template:Album ratings",
"Template:Cite web",
"Template:Other uses",
"Template:Use British English",
"Template:Use dmy dates",
"Template:Cite news",
"Template:Authority control",
"Template:Infobox Radio Show"
] | https://en.wikipedia.org/wiki/Blue_Jam |
6,321 | Channel 4 | Channel 4 is a British free-to-air public broadcast television channel owned and operated by Channel Four Television Corporation. It is publicly owned but, unlike the BBC, it receives no public funding and is funded entirely by its commercial activities, including publicity. It began its transmission in 1982 and was established to provide a fourth television service in the United Kingdom. At the time, the only other channels were the licence-funded BBC1 and BBC2, and a single commercial broadcasting network ITV.
Originally a subsidiary of the Independent Broadcasting Authority (IBA), the station is now owned and operated by Channel Four Television Corporation, a public corporation of the Department for Culture, Media and Sport, which was established in 1990 and came into operation in 1993. Until 2010, Channel 4 did not broadcast in Wales, but many of its programmes were re-broadcast there by the Welsh fourth channel S4C. In 2010, Channel 4 extended service into Wales and became a nationwide television channel. The network's headquarters are in London and Leeds, with creative hubs in Glasgow and Bristol.
Before Channel 4 and S4C, Britain had three terrestrial television services: BBC1, BBC2, and ITV. The Broadcasting Act 1980 began the process of adding a fourth; Channel 4 was formally created, along with its Welsh counterpart, by an act of Parliament in 1982. After some months of test broadcasts, it began scheduled transmissions on 2 November 1982 from Scala House, the former site of the Scala Theatre.
The notion of a second commercial broadcaster in the United Kingdom had been around since the inception of ITV in 1954 and its subsequent launch in 1955; the idea of an "ITV2" was long expected and pushed for. Indeed, television sets sold throughout the 1970s and early 1980s often had a spare tuning button labelled "ITV 2" or "IBA 2". Throughout ITV's history and until Channel 4 finally became a reality, a perennial dialogue existed between the GPO, the government, the ITV companies and other interested parties, concerning the form such an expansion of commercial broadcasting would take. Most likely, politics had the biggest impact leading to a delay of almost three decades before the second commercial channel became a reality.
One clear benefit of the "late arrival" of the channel was that its frequency allocations at each transmitter had already been arranged in the early 1960s when the launch of an ITV2 was anticipated. This led to very good coverage across most of the country and few problems of interference with other UK-based transmissions; a stark contrast to the problems associated with Channel 5's launch almost 15 years later. "ITV2" is not to be confused with ITV's digital television channel launched in 1998.
At the time the fourth service was being considered, a movement in Wales lobbied for the creation of dedicated service that would air Welsh language programmes, then only catered for at "off peak" times on BBC Wales and HTV. The campaign was taken so seriously by Gwynfor Evans, former president of Plaid Cymru, that he threatened the government with a hunger strike were it not to honour the plans.
The result was that Channel 4 as seen by the rest of the United Kingdom would be replaced in Wales by Sianel Pedwar Cymru (S4C) ("Channel Four Wales"). Operated by a specially created authority, S4C would air programmes in Welsh made by HTV, the BBC and independent companies. Initially limited frequency space meant that Channel 4 could not be broadcast alongside S4C, though some Channel 4 programmes would be aired at less popular times on the Welsh variant; this practice continued until the closure of S4C's analogue transmissions in 2010, at which time S4C became a fully Welsh channel. With this conversion of the Wenvoe transmitter group in Wales to digital terrestrial broadcasting on 31 March 2010, Channel 4 became a UK-wide television channel for the first time.
Since then, carriage on digital cable, satellite and digital terrestrial has introduced Channel 4 to Welsh homes where it is now universally available.
The first voice heard on Channel 4's opening day of 2 November 1982 was that of continuity announcer Paul Coia who said: "Good afternoon. It's a pleasure to be able to say to you, welcome to Channel Four." Following the announcement, the channel headed into a montage of clips from its programmes set to the station's signature tune, "Fourscore", written by David Dundas, which would form the basis of the station's jingles for its first decade. The first programme to air on the channel was the teatime game show Countdown, produced by Yorkshire Television, at 16:45. The first person to be seen on Channel 4 was Richard Whiteley, with Ted Moult being the second. The first woman on the channel, contrary to popular belief, was not Whiteley's Countdown co-host Carol Vorderman, but a lexicographer only ever identified as Mary. Whiteley opened the show with the words: "As the countdown to a brand new channel ends, a brand new countdown begins." On its first day, Channel 4 also broadcast the soap opera Brookside, which often ran storylines thought to be controversial; this ran until 2003.
At its launch, Channel 4 committed itself to providing an alternative to the existing channels, an agenda in part set out by its remit which required the provision of programming to minority groups. In step with its remit, the channel became well received both by minority groups and the arts and cultural worlds during this period under founding chief executive Jeremy Isaacs, where the channel gained a reputation for programmes on the contemporary arts. Two programmes captured awards from the Broadcasting Press Guild in March 1983: Best comedy for The Comic Strip Presents…Five Go Mad in Dorset, and best on-screen performance in a non-acting role for Tom Keating in his series On Painters. Channel 4 co-commissioned Robert Ashley's television opera Perfect Lives, which it premiered over several episodes in 1984. The channel often did not receive mass audiences for much of this period, however, as might be expected for a station focusing on minority interests. During this time Channel 4 also began the funding of independent films, such as the Merchant Ivory docudrama The Courtesans of Bombay.
In 1992, Channel 4 faced its first libel case by Jani Allan, a South African journalist, who objected to her representation in Nick Broomfield's documentary The Leader, His Driver and the Driver's Wife.
In September 1993, the channel broadcast the direct-to-TV documentary film Beyond Citizen Kane, in which it displayed the dominant position of the Rede Globo (now TV Globo) television network, and discussed its influence, power, and political connections in Brazil.
After control of the station passed from the Channel Four Television Company to the Channel Four Television Corporation in 1993, a shift in broadcasting style took place. Instead of aiming for minority tastes, it began to focus on the edges of the mainstream, and the centre of the mass market itself. It began to show many US programmes in peak viewing time, far more than it had previously done. It gave such shows as Friends and ER their UK premières.
In the early 2000s, Channel 4 began broadcasting reality formats such as Big Brother and obtained the rights to broadcast mass appeal sporting events like cricket and horse racing. This new direction increased ratings and revenues.
In addition, the corporation launched several new television channels through its new 4Ventures offshoot, including Film4, At the Races, E4 and More4.
Partially in reaction to its new "populist" direction, the Communications Act 2003 directed the channel to demonstrate innovation, experimentation, and creativity, appeal to the tastes and interests of a culturally diverse society, and include programmes of an educational nature which exhibit a distinctive character.
On 31 December 2004, Channel 4 launched a 'brand' new look and new visual identity in which the logo is disguised as different objects and the "4" can be seen in an angle.
Under the leadership of Freeview founder Andy Duncan, 2005 saw a change of direction for Channel 4's digital channels. Channel 4 made E4 free-to-air on digital terrestrial television, and launched a new free-to-air digital channel called More4. By October, Channel 4 had joined the Freeview consortium. By July 2006, Film4 had likewise become free-to-air and restarted broadcasting on digital terrestrial.
Venturing into radio broadcasting, 2005 saw Channel 4 purchase 51 per cent of shares in the now defunct Oneword radio station, with UBC Media holding on to the remaining shares. New programmes such as the weekly, half-hour The Morning Report news programme were among some of the new content Channel 4 provided for the station, with the name 4Radio being used. As of early 2009, however, Channel 4's future involvement in radio remained uncertain.
On 2 November 2007, the station celebrated its 25th birthday. It showed the first episode of Countdown, an anniversary Countdown special, as well as a special edition of The Big Fat Quiz and using the original multicoloured 1982–1996 blocks logo on presentation and idents using the Fourscore jingle throughout the day.
In November 2009, Channel 4 launched a week of 3D television, broadcasting selected programmes each night using stereoscopic ColorCode 3D technology. The accompanying 3D glasses were distributed through Sainsbury's supermarkets.
On 29 September 2015, Channel 4 revamped its presentation for a fifth time; the new branding downplayed the "4" logo from most on-air usage, in favour of using the shapes from the logo in various forms. Four new idents were filmed by Jonathan Glazer, which featured the shapes in various real-world scenes depicting the "discovery" and "origins" of the shapes. The full logo was still occasionally used, but primarily for off-air marketing. Channel 4 also commissioned two new corporate typefaces, "Chadwick", and "Horseferry" (a variation of Chadwick with the aforementioned shapes incorporated into its letter forms), for use across promotional material and on-air.
On 31 October 2017, Channel 4 introduced a new series of idents continuing the theme, this time depicting the logo shapes as having formed into an anthropomorphic "giant" character.
Before the digital switch-over, Channel 4 raised concerns over how it might finance its public service obligations afterward. In April 2006, it was announced that Channel 4's digital switch-over costs would be paid for by licence fee revenues.
On 28 March 2007, Channel 4 announced plans to launch a music channel "4Music" as a joint venture with British media company EMAP, which would include carriage on the Freeview platform. On 15 August 2008, 4Music was launched across the UK. Channel 4 announced interest in launching a high-definition version of Film4 on Freeview, to coincide with the launch of Channel 4 HD. However, the fourth HD slot was given to Channel 5 instead. Channel 4 has since acquired a 50 per cent stake in EMAP's TV business for a reported £28 million.
In June 2017, it was announced that Alex Mahon would be the next chief executive, and would take over from David Abraham, who left in November 2017.
On 25 September 2021, Channel 4 and several of its sub-channels went off air after an incident at Red Bee Media's playout centre in west London. Channel 4, More4, Film4, E4, 4Music, The Box, Box Hits, Kiss, Magic and Kerrang! were impacted (4seven was not impacted), with the incident still affecting a number of the channels on 30 September 2021. The London Fire Brigade confirmed that a gas fire prevention system at the site had been activated, but firefighters found no sign of fire. Activation of the fire suppression system caused catastrophic damage to some systems, such as Channel 4's subtitles, signing, and audio description system. An emergency backup subtitling system also failed, leaving Channel 4 unable to provide access services to viewers. This situation was criticised by the National Deaf Children's Society, which complained to the broadcasting watchdog. A new subtitling, signing and audio description system had to be built from scratch. The service eventually began to return at the end of October. In June 2022 after a six-month long investigation, Ofcom found that Channel 4 had breached its broadcast licence conditions on two grounds: Missing its subtitles quota on Freesat for 2021 and failure to effectively communicate with affected audiences.
On 23 December 2021, Jon Snow presented Channel 4 News for the last time, after 32 years as a main presenter on the programme, making Snow one of the UK's longest-serving presenters on a national news programme.
Channel 4's parent company, Channel Four Television Corporation, was considered for privatisation by the governments of Margaret Thatcher, John Major and Tony Blair. In 2014, the Cameron-Clegg coalition government drew up proposals to privatise the corporation but the sale was blocked by the Liberal Democrat Business Secretary Vince Cable. In 2016, the future of the channel was again being looked into by the government, with analysts suggesting several options for its future. In June 2021, the government of Boris Johnson was considering selling the channel.
In April 2022, the Department for Culture, Media and Sport acknowledged that ministerial discussions were taking place regarding the sale of Channel Four Television Corporation. The channel's chief executive, Alex Mahon, expressed disappointment at this, saying that its vision for the future was "rooted in continued public ownership".
In January 2023, Michelle Donelan confirmed that the plans to sell Channel 4 were scrapped and that it would remain in public ownership for the foreseeable future.
Channel 4 was established with, and continues to hold, a remit of public service obligations which it must fulfil. The remit changes periodically, as dictated by various broadcasting and communications acts, and is regulated by the various authorities Channel 4 has been answerable to; originally the IBA, then the ITC and now Ofcom.
The preamble of the remit as per the Communications Act 2003 states that:
The public service remit for Channel 4 is the provision of a broad range of high quality and diverse programming which, in particular:
The remit also involves an obligation to provide programming for schools, and a substantial amount of programming produced outside of Greater London.
Channel 4 was carried from its beginning on analogue terrestrial, the standard means of television broadcast in the United Kingdom. It continued to be broadcast through these means until the changeover to digital terrestrial television in the United Kingdom was complete. Since 1998, it has been universally available on digital terrestrial, and the Sky platform (initially encrypted, though encryption was dropped on 14 April 2008 and is now free of charge and available on the Freesat platform) as well as having been available from various times in various areas, on analogue and digital cable networks.
Due to its special status as a public service broadcaster with a specific remit, it is afforded free carriage on the terrestrial platforms, in contrast with other broadcasters such as ITV.
Channel 4 is available outside the United Kingdom; it is widely available in the Republic of Ireland, the Netherlands, Belgium and Switzerland. The channel is registered to broadcast within the European Union/EEA through the Luxembourg Broadcasting Regulator (ALIA).
Since 2019, it has been offered by British Forces Broadcasting Service (BFBS) to members of the British Armed Forces and their families around the world, BFBS Extra having previously carried a selection of Channel 4 programmes.
The Channel 4 website allows people in the United Kingdom to watch Channel 4 live on the Internet. Previously, some programmes (mostly international imports) were not shown. Channel 4 is also provided by Virgin Mobile's DAB mobile TV service, which has the same restrictions as the Internet live stream. Channel 4 is also carried by the Internet TV service TVCatchup and was previously carried by Zattoo until the operator removed the channel from its platform.
Channel 4 also makes some of its programming available "on demand" via cable and the Internet through Channel 4.
During its first decade, Channel 4 was funded by subscriptions collected by the IBA from the ITV regional companies, in return for which each company had the right to sell advertisements on the fourth channel in its own region and keep the proceeds. This meant that ITV and Channel 4 were not in competition with each other, and often promoted each other's programmes.
A change in funding came about under the Broadcasting Act 1990 when the new corporation was afforded the ability to fund itself. Originally this arrangement left a "safety net" guaranteed minimum income should the revenue fall too low, funded by large insurance payments made to the ITV companies. Such a subsidy was never required, however, and these premiums were phased out by the government in 1998. After the link with ITV was cut, the cross-promotion which had existed between ITV and Channel 4 also ended.
In 2007, owing to severe funding difficulties, the channel sought government help and was granted a payment of £14 million over a six-year period. The money was to have come from the television licence fee, and would have been the first time that money from the licence fee had been given to any broadcaster other than the BBC. However, the plan was scrapped by the Secretary of State for Culture, Media and Sport, Andy Burnham, ahead of "broader decisions about the future framework of public service broadcasting". The broadcasting regulator Ofcom released its review in January 2009 in which it suggested that Channel 4 would preferably be funded by "partnerships, joint ventures or mergers".
As of 2022, it breaks even in much the same way as most privately run commercial stations through the sale of on-air advertising, programme sponsorship, and the sale of any programme content and merchandising rights it owns, such as overseas broadcasting rights and domestic video sales. For example, as of 2012 its total revenues were £925 million with 91 per cent derived from sale of advertising. It also has the ability to subsidise the main network through any profits made on the corporation's other endeavours, which have in the past included subscription fees from stations such as E4 and Film4 (now no longer subscription services) and its "video-on-demand" sales. In practice, however, these other activities are loss-making, and are subsidised by the main network. According to Channel 4's last published accounts, for 2005, the extent of this cross-subsidy was some £30 million.
Channel 4 is a "publisher-broadcaster", meaning that it commissions or "buys" all of its programming from companies independent of itself. It was the first UK broadcaster to do so on a significant scale; such commissioning is a stipulation which is included in its licence to broadcast. In consequence, numerous independent production companies emerged, though external commissioning on the BBC and in ITV (where a quota of 25 per cent minimum of total output has been imposed since the Broadcasting Act 1990 came into force) has become regular practice, as well as on the numerous stations that launched later. Although it was the first British broadcaster to commission all of its programmes from third parties, Channel 4 was the last terrestrial broadcaster to outsource its transmission and playout operations (to Red Bee Media), after 25 years in-house.
The requirement to obtain all content externally is stipulated in its licence. Additionally, Channel 4 also began a trend of owning the copyright and distribution rights of the programmes it aired, in a manner that is similar to the major Hollywood studios' ownership of television programmes that they did not directly produce. Thus, although Channel 4 does not produce programmes, many are seen as belonging to it.
It was established with a specific intention of providing programming to groups of minority interests, not catered for by its competitors, which at the time were only the BBC and ITV.
Channel 4 also pioneered the concept of 'stranded programming', where seasons of programmes following a common theme would be aired and promoted together. Some would be very specific, and run for a fixed period of time; the 4 Mation season, for example, showed innovative animation. Other, less specific strands, were (and still are) run regularly, such as T4, a strand of programming aimed at teenagers, on weekend mornings (and weekdays during school/college holidays); Friday Night Comedy, a slot where the channel would pioneer its style of comedy commissions, 4Music (now a separate channel) and 4Later, an eclectic collection of offbeat programmes transmitted in the early hours of the morning.
For a period in the mid-1980s, some art-house films (dubbed by Channel 4's critics as being pornographic) would be screened with a red triangle graphic in the upper right of the screen.
In recent years concerns have arisen regarding a number of programmes made for Channel 4, that are believed missing from all known archives.
The following is a list of the 10 most watched shows on Channel 4 since launch, based on Live +28 data supplied by BARB, and archival data published by Channel 4.
During the station's early days, the screenings of innovative short one-off comedy films produced by a rotating line-up of alternative comedians went under the title of The Comic Strip Presents. The Tube and Saturday Live/Friday Night Live also launched the careers of a number of comedians and writers. Channel 4 broadcast a number of popular American imports, including The Cosby Show, Roseanne, Home Improvement, Friends, Sex and the City, South Park and Will & Grace. Other significant US acquisitions include The Simpsons, for which the station was reported to have paid £700,000 per episode for the terrestrial television rights.
In April 2010, Channel 4 became the first UK broadcaster to adapt the American comedy institution of roasting to British television, with A Comedy Roast.
In 2010, Channel 4 organised Channel 4's Comedy Gala, a comedy benefit show in aid of Great Ormond Street Children's Hospital. With over 25 comedians appearing, it billed it as "the biggest live stand up show in United Kingdom history". Filmed live on 30 March in front of 14,000 at The O2 Arena in London, it was broadcast on 5 April. This has continued to 2016.
In 2021, Channel 4 decided to revive The British Comedy Awards as part of their Stand Up To Cancer programming. The ceremony, billed as The National Comedy Awards was due to be held in the spring of 2021 but was delayed due to the Coronavirus pandemic until 15 December 2021 and then cancelled a week before it was due to be held, due to concerns over the Omicron variant. The ceremony was finally held on 2 March 2022 and broadcast on Channel 4 three days later. The National Comedy Awards was not the only live comedy event that was part of the channel's Christmas schedule that was effected by these concerns as Joe Lycett: Mummy's Big Christmas Do! was also postponed, with the 22 December show due to air as a pilot for a new series called Mummy's House Party in spring 2022. Lycett's Birmingham-based extravaganza finally made it to air on 3 July 2022 as Joe Lycett's Big Pride Party, with 0.29 million viewers tuning in (compared to 0.69 million for The Cruise on Channel 5).
Channel 4 has a strong reputation for history programmes and documentaries. Its news service, Channel 4 News, is supplied by ITN whilst its long-standing investigative documentary series, Dispatches, gains attention from other media outlets. Its live broadcast of the first public autopsy in the UK for 170 years, carried out by Gunther von Hagens in 2002 and the 2003 one-off stunt Derren Brown Plays Russian Roulette Live proved controversial.
A season of television programmes about masturbation, called Wank Week, was to be broadcast in the United Kingdom by Channel 4 in March 2007. The series came under public attack from senior television figures, and was pulled amid claims of declining editorial standards and concern for the channel's public service broadcasting credentials.
FourDocs was an online documentary site provided by Channel 4. It allowed viewers to upload their own documentaries to the site for others to view. It focused on documentaries of between 3 and 5 minutes. The website also included an archive of classic documentaries, interviews with documentary filmmakers and short educational guides to documentary-making. It won a Peabody Award in 2006. The site also included a strand for documentaries of under 59 seconds, called "Microdocs".
Channel 4 is obliged to carry schools programming as part of its remit and licence.
Since 1957 ITV had produced schools programming, which became an obligation. In 1987, five years after the station was launched, the IBA afforded ITV free carriage of these programmes during Channel 4's then-unused weekday morning hours. This arrangement allowed the ITV companies to fulfil their obligation to provide schools programming, whilst allowing ITV itself to broadcast regular programmes complete with advertisements. During the times in which schools programmes were aired Central Television provided most of the continuity with play-out originating from Birmingham.
After the restructuring of the station in 1993, ITV's obligations to provide such programming on Channel 4's airtime passed to Channel 4 itself, and the new service became Channel 4 Schools, with the new corporation administering the service and commissioning its programmes, some still from ITV, others from independent producers.
In March 2008, the 4Learning interactive new media commission Slabovia.tv was launched. The Slabplayer online media player showing TV shows for teenagers was launched on 26 May 2008.
The schools programming has always had elements which differ from its normal presentational package. In 1993, the Channel 4 Schools idents featured famous people in one category, with light shining on them in front of an industrial-looking setting supplemented by instrumental calming music. This changed in 1996 with the circles look to numerous children touching the screen, forming circles of information then picked up by other children. The last child would produce the Channel 4 logo in the form of three vertical circles, with another in the middle and to the left containing the Channel 4 logo.
A present feature of presentation was a countdown sequence featuring, in 1993 a slide with the programme name, and afterwards an extended sequence matching the channel branding. In 1996, this was an extended ident with timer in top left corner, and in 1999 following the adoption of the squares look, featured a square with timer slowly make its way across the right of the screen with people learning and having fun while doing so passing across the screen. It finished with the Channel 4 logo box on the right of the screen and the name 'Channel 4 Schools' being shown. This was adapted in 2000 when the service's name was changed to '4Learning'.
In 2001, this was altered to various scenes from classrooms around the world and different parts of school life. The countdown now flips over from the top, right, bottom and left with each second, and ends with four coloured squares, three of which are aligned vertically to the left of the Channel 4 logo, which is contained inside the fourth box. The tag 'Learning' is located directly beneath the logo. The final countdown sequence lasted between 2004 and 2005 and featured a background video of current controversial issues, overlaid with upcoming programming information. The video features people in the style of graffiti enacting the overuse of CCTV cameras, fox hunting, computer viruses and pirate videos, relationships, pollution of the seas and violent lifestyles. Following 2005, no branded section has been used for schools programmes.
From the outset, Channel 4 did not conform to the expectations of conventional religious broadcasting in the UK. John Ranelagh, first Commissioning Editor for Religion, made his priority 'broadening the spectrum of religious programming' and more 'intellectual' concerns. He also ignored the religious programme advisory structure that had been put in place by the BBC, and subsequently adopted by ITV. Ranelagh's first major commission caused a furore, a three-part documentary series called Jesus: The Evidence. The programmes, transmitted during the Easter period of 1984, seemed to advocate the idea that the Gospels were unreliable, Jesus may have indulged in witchcraft, and that he may not have even existed. The series triggered a public outcry, and marked a significant moment in the deterioration in the relationship between the UK's broadcasting and religious institutions.
Numerous genres of film-making – such as comedy, drama, documentary, adventure/action, romance and horror/thriller – are represented in the channel's schedule. From the launch of Channel 4 until 1998, film presentations on C4 would often be broadcast under the "Film on Four" banner.
In March 2005, Channel 4 screened the uncut Lars von Trier film The Idiots, which includes unsimulated sexual intercourse, making it the first UK terrestrial channel to do so. The channel had previously screened other films with similar material but censored and with warnings.
Since 1 November 1998, Channel 4 has had a digital subsidiary channel dedicated to the screening of films. This channel launched as a paid subscription channel under the name "FilmFour", and was relaunched in July 2006 as a free-to-air channel under the current name of "Film4". The Film4 channel carries a wide range of film productions, including acquired and Film4-produced projects. Channel 4's general entertainment channels E4 and More4 also screen feature films at certain points in the schedule as part of their content mix.
On 8 March 2007, Channel 4 screened a documentary, The Great Global Warming Swindle stating that global warming is "a lie" and "the biggest scam of modern times". The programme's accuracy were disputed on multiple points, and commentators criticised it for being one-sided, observing that the mainstream position on global warming is supported by the scientific academies of the major industrialised nations. There were 246 complaints to Ofcom as of 25 April 2007, including allegations that the programme falsified data. The programme was criticised by scientists and scientific organisations, and various scientists who participated in the documentary claimed their views had been distorted.
Against Nature: An earlier controversial Channel 4 programme made by Martin Durkin which was also critical of the environmental movement and was charged by the UK's Independent Television Commission for misrepresenting and distorting the views of interviewees by selective editing.
The Greenhouse Conspiracy: An earlier Channel 4 documentary broadcast on 12 August 1990, as part of the Equinox series, in which similar claims were made. Three of the people interviewed (Lindzen, Michaels and Spencer) were also interviewed in The Great Global Warming Swindle.
In the Alternative Christmas address of 2008, a Channel 4 tradition since 1993 with a different presenter each year, Iranian President Mahmoud Ahmadinejad made a thinly veiled attack on the United States by claiming that Christ would have been against "bullying, ill-tempered and expansionist powers".
The broadcast was rebuked by human rights activists, politicians and religious figures, including Peter Tatchell, Louise Ellman, Ron Prosor and Rabbi Aaron Goldstein. A spokeswoman for the Foreign and Commonwealth Office said: "President Ahmadinejad has, during his time in office, made a series of appalling anti-Semitic statements. The British media are rightly free to make their own editorial choices, but this invitation will cause offence and bemusement not just at home but among friendly countries abroad".
However, Channel 4 was defended by Stonewall director Ben Summerskill who stated: "In spite of his ridiculous and often offensive views, it is an important way of reminding him that there are some countries where free speech is not repressed...If it serves that purpose, then Channel 4 will have done a significant public service". Dorothy Byrne, Channel 4's head of news and current affairs, said in response to the station's critics: "As the leader of one of the most powerful states in the Middle East, President Ahmadinejad's views are enormously influential... As we approach a critical time in international relations, we are offering our viewers an insight into an alternative world view...Channel 4 has devoted more airtime to examining Iran than any other broadcaster and this message continues a long tradition of offering a different perspective on the world around us".
4Talent is an editorial branch of Channel 4's commissioning wing, which co-ordinates Channel 4's various talent development schemes for film, television, radio, new media and other platforms and provides a showcasing platform for new talent.
There are bases in London, Birmingham, Glasgow and Belfast, serving editorial hubs known respectively as 4Talent National, 4Talent Central England, 4Talent Scotland and 4Talent Northern Ireland. These four sites include features, profiles and interviews in text, audio and video formats, divided into five zones: TV, Film, Radio, New Media and Extras, which covers other arts such as theatre, music and design. 4Talent also collates networking, showcasing and professional development opportunities, and runs workshops, masterclasses, seminars and showcasing events across the UK.
4Talent Magazine is the creative industries magazine from 4Talent, which launched in 2005 as TEN4 magazine under the editorship of Dan Jones. 4Talent Magazine is currently edited by Nick Carson. Other staff include deputy editor Catherine Bray and production editor Helen Byrne. The magazine covers rising and established figures of interest in the creative industries, a remit including film, radio, TV, comedy, music, new media and design.
Subjects are usually UK-based, with contributing editors based in Northern Ireland, Scotland, London and Birmingham, but the publication has been known to source international content from Australia, America, continental Europe and the Middle East. The magazine is frequently organised around a theme for the issue, for instance giving half of November 2007's pages over to profiling winners of the annual 4Talent Awards.
An unusual feature of the magazine's credits is the equal prominence given to the names of writers, photographers, designers and illustrators, contradicting standard industry practice of more prominent writer bylines. It is also recognisable for its 'wraparound' covers, which use the front and back as a continuous canvas – often produced by guest artists.
Although 4Talent Magazine is technically a newsstand title, a significant proportion of its readers are subscribers. It started life as a quarterly 100-page title, but has since doubled in size and is now published bi-annually.
Since the 2010s, Channel 4 has become the public service broadcaster most likely to amend their schedule at short notice, if programmes are not gaining sufficient viewers in their intended slots. Programmes which have been heavily promoted by the channel before launch and then have lost their slot a week later include Sixteen: Class of 2021. This was a fly-on-the-wall school documentary which lost its prime 9pm slot after one episode on 31 August 2021, even with a 4 star review in The Guardian. Channel 4 moved the next episode to a late night (post-primetime) slot on a different day and continued to broadcast the remainder of the four-part series in this timeslot.
Also in 2021, the channel launched Epic Wales: Valleys, Mountains and Coast, a version of their More4 documentaries The Pennines: Backbone of Britain, The Yorkshire Dales and The Lakes and Devon and Cornwall. set in Wales. Epic Wales: Valleys, Mountains and Coast. was initially broadcast in a prime Friday night slot at 8pm, in the hour before their comedy shows, but was dumped by the channel before the series was completed and replaced by repeats. In February 2022, the channel scheduled a new version of the show under the title Wonderous Wales with a Saturday night slot at 8pm but after one episode, they decided to take this series out of their schedule, moving up a repeat of Matt Baker: Our Farm in the Dales to 8pm and putting an episode of Escape to the Chateau in Baker's slot at 7pm. Other programmes moved out of primetime in 2022, include Mega Mansion Hunters, Channel 4's answer to Selling Sunset, which saw its third and final episode moved past midnight with repeats put in the schedule before it, and Richard Hammond's Crazy Contraptions, a primetime Friday night competitive engineering show which saw its grand final moved to 11pm on a Sunday night. Instead of Hammond's competition, Channel 4 decided to schedule the fifth series of Devon and Cornwall in its place at 8pm on Friday nights, with this documentary being put up against Channel 5's World's Most Scenic Railway Journeys in the same timeslot.
A new series of Unreported World was due to start on 18 February 2022 with a report by Seyi Rhodes in South Sudan, but was dropped due to an extended storm report on Channel 4 News. When the programme was rescheduled for following Fridays, it was dropped again as Channel 4 News was extended due to the 2022 Russian invasion of Ukraine. Winter Paralympics: Today in Beijing is due to take the Unreported World slot from 11 March 2022 though this sports programme may also be moved around the schedule to continue the extended news programmes reporting on the conflict. The invasion of Ukraine has also prompted Channel 4 to acquire and schedule the comedy series Servant of the People as a last minute replacement. The programme stars the current President of Ukraine Volodymyr Zelenskyy as an ordinary man who gets elected to run the country, and will be shown on 6 March 2022 along with the documentary Zelenskyy: The Man Who Took on Putin.
In addition to these shows, O.T. Fagbenle's sitcom Maxxx was pulled from their youth TV channel E4, after one episode from the series had been broadcast on 2 April 2020, with Channel 4 deciding to keep the series off-air until Black History Month, with the series now going out on the main channel from October 2020.
In May 2022, the reality dating show Let's Make a Love Scene was scrapped after one episode with the second programme in the series, hosted by Ellie Taylor, pulled from the May 20 schedule and replaced with an episode of 8 Out of 10 Cats Does Countdown. The first edition was negatively received, with Anita Singh, the Arts and Entertainments Editor for The Telegraph writing that the show was "the most ill-conceived programme idea since Prince Edward dreamt up It's a Royal Knockout".
Since its launch in 1982, Channel 4 has used the same logo which consists of a stylised numeral "4" made up of nine differently-shaped blocks.
The original version was designed by Martin Lambie-Nairn and his partner Colin Robinson and was the first UK channel ident made using advanced computer generation (the first electronically-generated ident was on BBC2 in 1979, but this was two-dimensional). It was designed in conjunction with Bo Gehring Aviation of Los Angeles and originally depicted the "4" in red, yellow, green, blue and purple. The music accompanying the ident was called "Fourscore" and was composed by David Dundas; it was later released as a single alongside a B-side, "Fourscore Two", although neither reached the UK charts. In November 1992, "Fourscore" was replaced by new music.
In 1996, Channel 4 commissioned Tomato Films to revamp the "4", which resulted in the "Circles" idents showing four white circles forming up transparently over various scenes, with the "4" logo depicted in white in one of the circles.
In 1999, Spin redesigned the logo to feature in a single square that sat on the right-hand side of the screen, whilst various stripes would move along from left to right, often lighting the squared "4" up. Like previous "Circles" idents from 1996 (which was made by Tomato Films), the stripes would be interspersed with various scenes potentially related to the upcoming programme.
The logo was made three-dimensional again in 2004 when it was depicted in filmed scenes that show the blocks forming the "4" logo for less than a second before the action moves away again.
In 2015, the logo was disassembled completely to allow the blocks to appear as parts of a nature scene, sometimes featuring a strange dancing creature and sometimes being excavated for scientific study, one being studied under a microscope and showing a tardigrade. The second wave of these idents, launched in 2017, depict a giant creature made of the "4" blocks (made to look almost like a person) interacting with everyday life, sometimes shouting the "Fourscore" theme as a foghorn.
The original 1982 ident was given a one-off revival on 28 December 2020, as a tribute to Lambie-Nairn after his death three days earlier. It was also used on 22 January 2021 as part of the 80s-themed "takeover" to promote the premiere of It's a Sin, which was set during the 1980s AIDS crisis.
The Channel 4 logo was reassembled in 2023 in an all-lime green colour to promote the network's new digital-first strategy, which included its streaming service All 4 being renamed under the Channel 4 brand. This was then followed by the launch of a new idents package on 14 June 2023.
Channel 4 has, since its inception, broadcast identical programmes and continuity throughout the United Kingdom (excluding Wales where it did not operate on analogue transmitters). At launch this made it unique, as both the BBC and ITV had long-established traditions of providing regional variations in their programming in different areas of the country. Since the launch of subsequent British television channels, Channel 4 has become typical in its lack of regional programming variations.
A few exceptions exist to this rule for programming and continuity:
Part of Channel 4's remit covers the commissioning of programmes from outside London. Channel 4 has a dedicated director of nations and regions, Stuart Cosgrove, who is based in a regional office in Glasgow. As his job title suggests, it is his responsibility to foster relations with independent producers based in areas of the United Kingdom (including Wales) outside London.
Channel 4 is available in Ireland, with adverts tailored to the Irish market. The channel is registered with the broadcasting regulators in Luxembourg for terms of conduct and business within the EU/EEA while observing guidelines outlined by Ireland's BAI code. Irish advertising sales are managed by Media Link in Dublin. Where Channel 4 does not hold broadcasting rights within the Republic of Ireland such programming is unavailable. For example, the series Glee was not available on Channel 4 on Sky in Ireland due to it broadcasting on TV3 within Ireland. Currently, programming available on Channel 4 is available within the Republic of Ireland without restrictions. Elsewhere in Europe, the UK version of the channel is available.
With ITV plc pushing for much looser requirements on the amount of regional news and other programming it is obliged to broadcast in its ITV regions, the idea of Channel 4 taking on a regional news commitment has been considered, with the corporation in talks with Ofcom and ITV over the matter. Channel 4 believe that a scaling-back of such operations on ITV's part would be detrimental to Channel 4's national news operation, which shares much of its resources with ITV through their shared news contractor ITN. At the same time, Channel 4 also believe that such an additional public service commitment would bode well in on-going negotiations with Ofcom in securing additional funding for its other public service commitments.
In mid-2006 Channel 4 ran a six-month closed trial of HDTV, as part of the wider Freeview HD experiment via the Crystal Palace transmitter to London and parts of the home counties, including the use of Lost and Desperate Housewives as part of the experiment, as US broadcasters such as ABC already have an HDTV back catalogue.
On 10 December 2007, Channel 4 launched a high-definition television simulcast of Channel 4 on Sky's digital satellite platform, after Sky agreed to contribute toward the channel's satellite distribution costs. It was the first full-time high-definition channel from a terrestrial UK broadcaster.
On 31 July 2009, Virgin Media added Channel 4 HD on channel 146 (later on channel 142, now on channel 141) as part of the M pack. On 25 March 2010 Channel 4 HD appeared on Freeview channel 52 with a placeholding caption, ahead of a commercial launch on 30 March 2010, coinciding with the commercial launch of Freeview HD. On 19 April 2011, Channel 4 HD was added to Freesat on channel 126. As a consequence, the channel moved from being free-to-view to free-to-air on satellite during March 2011. With the closure of S4C Clirlun in Wales on 1 December 2012, on Freeview, Channel 4 HD launched in Wales on 2 December 2012.
The channel carries the same schedule as Channel 4, broadcasting programmes in HD when available, acting as a simulcast. Therefore, SD programming is broadcast upscaled to HD. The first true HD programme to be shown was the 1996 Adam Sandler film Happy Gilmore. From launch until 2016 the presence of the 4HD logo on screen denoted true HD content.
On 1 July 2014, Channel 4 +1 HD, an HD simulcast of Channel 4 +1, launched on Freeview channel 110. It closed on 22 June 2020 to help make room on COM7 following the closure of COM8 on Freeview. 4Seven HD were removed from Freeview also.
On 20 February 2018, Channel 4 announced that Channel 4 HD and All 4 would no longer be supplied on Freesat from 22 February 2018. Channel 4 HD returned to the platform on 8 December 2021, along with the music channel portfolio of The Box Plus Network.
On 27 September 2022, the other 6 advertising regions of Channel 4 (South, Midlands, North, Scotland, Northern Ireland and Rep of Ireland) were made available in HD on Sky and Virgin Media. Prior to this, Channel 4 HD was only available in the London advertising region.
Channel 4's video on demand service, known simply as "Channel 4" since April 2023, launched in November 2006 as "4oD", and was renamed "All 4" in March 2015. The service offers a variety of programmes recently shown on Channel 4, E4, More4 or from their archives, though some programmes and movies are not available due to rights issues.
Channel 4 originally licensed an ancillary teletext service to provide schedules, programme information and features. The original service was called 4-Tel, and was produced by Intelfax, a company set up especially for the purpose. It was carried in the 400s on Oracle. In 1993, with Oracle losing its franchise to Teletext Ltd, 4-Tel found a new home in the 300s, and had its name shown in the header row. Intelfax continued to produce the service and in 2002 it was renamed FourText.
In 2003, Channel 4 awarded Teletext Ltd a ten-year contract to run the channel's ancillary teletext service, named Teletext on 4. The service closed in 2008, and Teletext is no longer available on Channel 4, ITV and Channel 5. | [
{
"paragraph_id": 0,
"text": "Channel 4 is a British free-to-air public broadcast television channel owned and operated by Channel Four Television Corporation. It is publicly owned but, unlike the BBC, it receives no public funding and is funded entirely by its commercial activities, including publicity. It began its transmission in 1982 and was established to provide a fourth television service in the United Kingdom. At the time, the only other channels were the licence-funded BBC1 and BBC2, and a single commercial broadcasting network ITV.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Originally a subsidiary of the Independent Broadcasting Authority (IBA), the station is now owned and operated by Channel Four Television Corporation, a public corporation of the Department for Culture, Media and Sport, which was established in 1990 and came into operation in 1993. Until 2010, Channel 4 did not broadcast in Wales, but many of its programmes were re-broadcast there by the Welsh fourth channel S4C. In 2010, Channel 4 extended service into Wales and became a nationwide television channel. The network's headquarters are in London and Leeds, with creative hubs in Glasgow and Bristol.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Before Channel 4 and S4C, Britain had three terrestrial television services: BBC1, BBC2, and ITV. The Broadcasting Act 1980 began the process of adding a fourth; Channel 4 was formally created, along with its Welsh counterpart, by an act of Parliament in 1982. After some months of test broadcasts, it began scheduled transmissions on 2 November 1982 from Scala House, the former site of the Scala Theatre.",
"title": "History"
},
{
"paragraph_id": 3,
"text": "The notion of a second commercial broadcaster in the United Kingdom had been around since the inception of ITV in 1954 and its subsequent launch in 1955; the idea of an \"ITV2\" was long expected and pushed for. Indeed, television sets sold throughout the 1970s and early 1980s often had a spare tuning button labelled \"ITV 2\" or \"IBA 2\". Throughout ITV's history and until Channel 4 finally became a reality, a perennial dialogue existed between the GPO, the government, the ITV companies and other interested parties, concerning the form such an expansion of commercial broadcasting would take. Most likely, politics had the biggest impact leading to a delay of almost three decades before the second commercial channel became a reality.",
"title": "History"
},
{
"paragraph_id": 4,
"text": "One clear benefit of the \"late arrival\" of the channel was that its frequency allocations at each transmitter had already been arranged in the early 1960s when the launch of an ITV2 was anticipated. This led to very good coverage across most of the country and few problems of interference with other UK-based transmissions; a stark contrast to the problems associated with Channel 5's launch almost 15 years later. \"ITV2\" is not to be confused with ITV's digital television channel launched in 1998.",
"title": "History"
},
{
"paragraph_id": 5,
"text": "At the time the fourth service was being considered, a movement in Wales lobbied for the creation of dedicated service that would air Welsh language programmes, then only catered for at \"off peak\" times on BBC Wales and HTV. The campaign was taken so seriously by Gwynfor Evans, former president of Plaid Cymru, that he threatened the government with a hunger strike were it not to honour the plans.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "The result was that Channel 4 as seen by the rest of the United Kingdom would be replaced in Wales by Sianel Pedwar Cymru (S4C) (\"Channel Four Wales\"). Operated by a specially created authority, S4C would air programmes in Welsh made by HTV, the BBC and independent companies. Initially limited frequency space meant that Channel 4 could not be broadcast alongside S4C, though some Channel 4 programmes would be aired at less popular times on the Welsh variant; this practice continued until the closure of S4C's analogue transmissions in 2010, at which time S4C became a fully Welsh channel. With this conversion of the Wenvoe transmitter group in Wales to digital terrestrial broadcasting on 31 March 2010, Channel 4 became a UK-wide television channel for the first time.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "Since then, carriage on digital cable, satellite and digital terrestrial has introduced Channel 4 to Welsh homes where it is now universally available.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "The first voice heard on Channel 4's opening day of 2 November 1982 was that of continuity announcer Paul Coia who said: \"Good afternoon. It's a pleasure to be able to say to you, welcome to Channel Four.\" Following the announcement, the channel headed into a montage of clips from its programmes set to the station's signature tune, \"Fourscore\", written by David Dundas, which would form the basis of the station's jingles for its first decade. The first programme to air on the channel was the teatime game show Countdown, produced by Yorkshire Television, at 16:45. The first person to be seen on Channel 4 was Richard Whiteley, with Ted Moult being the second. The first woman on the channel, contrary to popular belief, was not Whiteley's Countdown co-host Carol Vorderman, but a lexicographer only ever identified as Mary. Whiteley opened the show with the words: \"As the countdown to a brand new channel ends, a brand new countdown begins.\" On its first day, Channel 4 also broadcast the soap opera Brookside, which often ran storylines thought to be controversial; this ran until 2003.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "At its launch, Channel 4 committed itself to providing an alternative to the existing channels, an agenda in part set out by its remit which required the provision of programming to minority groups. In step with its remit, the channel became well received both by minority groups and the arts and cultural worlds during this period under founding chief executive Jeremy Isaacs, where the channel gained a reputation for programmes on the contemporary arts. Two programmes captured awards from the Broadcasting Press Guild in March 1983: Best comedy for The Comic Strip Presents…Five Go Mad in Dorset, and best on-screen performance in a non-acting role for Tom Keating in his series On Painters. Channel 4 co-commissioned Robert Ashley's television opera Perfect Lives, which it premiered over several episodes in 1984. The channel often did not receive mass audiences for much of this period, however, as might be expected for a station focusing on minority interests. During this time Channel 4 also began the funding of independent films, such as the Merchant Ivory docudrama The Courtesans of Bombay.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "In 1992, Channel 4 faced its first libel case by Jani Allan, a South African journalist, who objected to her representation in Nick Broomfield's documentary The Leader, His Driver and the Driver's Wife.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "In September 1993, the channel broadcast the direct-to-TV documentary film Beyond Citizen Kane, in which it displayed the dominant position of the Rede Globo (now TV Globo) television network, and discussed its influence, power, and political connections in Brazil.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "After control of the station passed from the Channel Four Television Company to the Channel Four Television Corporation in 1993, a shift in broadcasting style took place. Instead of aiming for minority tastes, it began to focus on the edges of the mainstream, and the centre of the mass market itself. It began to show many US programmes in peak viewing time, far more than it had previously done. It gave such shows as Friends and ER their UK premières.",
"title": "History"
},
{
"paragraph_id": 13,
"text": "In the early 2000s, Channel 4 began broadcasting reality formats such as Big Brother and obtained the rights to broadcast mass appeal sporting events like cricket and horse racing. This new direction increased ratings and revenues.",
"title": "History"
},
{
"paragraph_id": 14,
"text": "In addition, the corporation launched several new television channels through its new 4Ventures offshoot, including Film4, At the Races, E4 and More4.",
"title": "History"
},
{
"paragraph_id": 15,
"text": "Partially in reaction to its new \"populist\" direction, the Communications Act 2003 directed the channel to demonstrate innovation, experimentation, and creativity, appeal to the tastes and interests of a culturally diverse society, and include programmes of an educational nature which exhibit a distinctive character.",
"title": "History"
},
{
"paragraph_id": 16,
"text": "On 31 December 2004, Channel 4 launched a 'brand' new look and new visual identity in which the logo is disguised as different objects and the \"4\" can be seen in an angle.",
"title": "History"
},
{
"paragraph_id": 17,
"text": "Under the leadership of Freeview founder Andy Duncan, 2005 saw a change of direction for Channel 4's digital channels. Channel 4 made E4 free-to-air on digital terrestrial television, and launched a new free-to-air digital channel called More4. By October, Channel 4 had joined the Freeview consortium. By July 2006, Film4 had likewise become free-to-air and restarted broadcasting on digital terrestrial.",
"title": "History"
},
{
"paragraph_id": 18,
"text": "Venturing into radio broadcasting, 2005 saw Channel 4 purchase 51 per cent of shares in the now defunct Oneword radio station, with UBC Media holding on to the remaining shares. New programmes such as the weekly, half-hour The Morning Report news programme were among some of the new content Channel 4 provided for the station, with the name 4Radio being used. As of early 2009, however, Channel 4's future involvement in radio remained uncertain.",
"title": "History"
},
{
"paragraph_id": 19,
"text": "On 2 November 2007, the station celebrated its 25th birthday. It showed the first episode of Countdown, an anniversary Countdown special, as well as a special edition of The Big Fat Quiz and using the original multicoloured 1982–1996 blocks logo on presentation and idents using the Fourscore jingle throughout the day.",
"title": "History"
},
{
"paragraph_id": 20,
"text": "In November 2009, Channel 4 launched a week of 3D television, broadcasting selected programmes each night using stereoscopic ColorCode 3D technology. The accompanying 3D glasses were distributed through Sainsbury's supermarkets.",
"title": "History"
},
{
"paragraph_id": 21,
"text": "On 29 September 2015, Channel 4 revamped its presentation for a fifth time; the new branding downplayed the \"4\" logo from most on-air usage, in favour of using the shapes from the logo in various forms. Four new idents were filmed by Jonathan Glazer, which featured the shapes in various real-world scenes depicting the \"discovery\" and \"origins\" of the shapes. The full logo was still occasionally used, but primarily for off-air marketing. Channel 4 also commissioned two new corporate typefaces, \"Chadwick\", and \"Horseferry\" (a variation of Chadwick with the aforementioned shapes incorporated into its letter forms), for use across promotional material and on-air.",
"title": "History"
},
{
"paragraph_id": 22,
"text": "On 31 October 2017, Channel 4 introduced a new series of idents continuing the theme, this time depicting the logo shapes as having formed into an anthropomorphic \"giant\" character.",
"title": "History"
},
{
"paragraph_id": 23,
"text": "Before the digital switch-over, Channel 4 raised concerns over how it might finance its public service obligations afterward. In April 2006, it was announced that Channel 4's digital switch-over costs would be paid for by licence fee revenues.",
"title": "History"
},
{
"paragraph_id": 24,
"text": "On 28 March 2007, Channel 4 announced plans to launch a music channel \"4Music\" as a joint venture with British media company EMAP, which would include carriage on the Freeview platform. On 15 August 2008, 4Music was launched across the UK. Channel 4 announced interest in launching a high-definition version of Film4 on Freeview, to coincide with the launch of Channel 4 HD. However, the fourth HD slot was given to Channel 5 instead. Channel 4 has since acquired a 50 per cent stake in EMAP's TV business for a reported £28 million.",
"title": "History"
},
{
"paragraph_id": 25,
"text": "In June 2017, it was announced that Alex Mahon would be the next chief executive, and would take over from David Abraham, who left in November 2017.",
"title": "History"
},
{
"paragraph_id": 26,
"text": "On 25 September 2021, Channel 4 and several of its sub-channels went off air after an incident at Red Bee Media's playout centre in west London. Channel 4, More4, Film4, E4, 4Music, The Box, Box Hits, Kiss, Magic and Kerrang! were impacted (4seven was not impacted), with the incident still affecting a number of the channels on 30 September 2021. The London Fire Brigade confirmed that a gas fire prevention system at the site had been activated, but firefighters found no sign of fire. Activation of the fire suppression system caused catastrophic damage to some systems, such as Channel 4's subtitles, signing, and audio description system. An emergency backup subtitling system also failed, leaving Channel 4 unable to provide access services to viewers. This situation was criticised by the National Deaf Children's Society, which complained to the broadcasting watchdog. A new subtitling, signing and audio description system had to be built from scratch. The service eventually began to return at the end of October. In June 2022 after a six-month long investigation, Ofcom found that Channel 4 had breached its broadcast licence conditions on two grounds: Missing its subtitles quota on Freesat for 2021 and failure to effectively communicate with affected audiences.",
"title": "History"
},
{
"paragraph_id": 27,
"text": "On 23 December 2021, Jon Snow presented Channel 4 News for the last time, after 32 years as a main presenter on the programme, making Snow one of the UK's longest-serving presenters on a national news programme.",
"title": "History"
},
{
"paragraph_id": 28,
"text": "Channel 4's parent company, Channel Four Television Corporation, was considered for privatisation by the governments of Margaret Thatcher, John Major and Tony Blair. In 2014, the Cameron-Clegg coalition government drew up proposals to privatise the corporation but the sale was blocked by the Liberal Democrat Business Secretary Vince Cable. In 2016, the future of the channel was again being looked into by the government, with analysts suggesting several options for its future. In June 2021, the government of Boris Johnson was considering selling the channel.",
"title": "History"
},
{
"paragraph_id": 29,
"text": "In April 2022, the Department for Culture, Media and Sport acknowledged that ministerial discussions were taking place regarding the sale of Channel Four Television Corporation. The channel's chief executive, Alex Mahon, expressed disappointment at this, saying that its vision for the future was \"rooted in continued public ownership\".",
"title": "History"
},
{
"paragraph_id": 30,
"text": "In January 2023, Michelle Donelan confirmed that the plans to sell Channel 4 were scrapped and that it would remain in public ownership for the foreseeable future.",
"title": "History"
},
{
"paragraph_id": 31,
"text": "Channel 4 was established with, and continues to hold, a remit of public service obligations which it must fulfil. The remit changes periodically, as dictated by various broadcasting and communications acts, and is regulated by the various authorities Channel 4 has been answerable to; originally the IBA, then the ITC and now Ofcom.",
"title": "Public service remit"
},
{
"paragraph_id": 32,
"text": "The preamble of the remit as per the Communications Act 2003 states that:",
"title": "Public service remit"
},
{
"paragraph_id": 33,
"text": "The public service remit for Channel 4 is the provision of a broad range of high quality and diverse programming which, in particular:",
"title": "Public service remit"
},
{
"paragraph_id": 34,
"text": "The remit also involves an obligation to provide programming for schools, and a substantial amount of programming produced outside of Greater London.",
"title": "Public service remit"
},
{
"paragraph_id": 35,
"text": "Channel 4 was carried from its beginning on analogue terrestrial, the standard means of television broadcast in the United Kingdom. It continued to be broadcast through these means until the changeover to digital terrestrial television in the United Kingdom was complete. Since 1998, it has been universally available on digital terrestrial, and the Sky platform (initially encrypted, though encryption was dropped on 14 April 2008 and is now free of charge and available on the Freesat platform) as well as having been available from various times in various areas, on analogue and digital cable networks.",
"title": "Carriage"
},
{
"paragraph_id": 36,
"text": "Due to its special status as a public service broadcaster with a specific remit, it is afforded free carriage on the terrestrial platforms, in contrast with other broadcasters such as ITV.",
"title": "Carriage"
},
{
"paragraph_id": 37,
"text": "Channel 4 is available outside the United Kingdom; it is widely available in the Republic of Ireland, the Netherlands, Belgium and Switzerland. The channel is registered to broadcast within the European Union/EEA through the Luxembourg Broadcasting Regulator (ALIA).",
"title": "Carriage"
},
{
"paragraph_id": 38,
"text": "Since 2019, it has been offered by British Forces Broadcasting Service (BFBS) to members of the British Armed Forces and their families around the world, BFBS Extra having previously carried a selection of Channel 4 programmes.",
"title": "Carriage"
},
{
"paragraph_id": 39,
"text": "The Channel 4 website allows people in the United Kingdom to watch Channel 4 live on the Internet. Previously, some programmes (mostly international imports) were not shown. Channel 4 is also provided by Virgin Mobile's DAB mobile TV service, which has the same restrictions as the Internet live stream. Channel 4 is also carried by the Internet TV service TVCatchup and was previously carried by Zattoo until the operator removed the channel from its platform.",
"title": "Carriage"
},
{
"paragraph_id": 40,
"text": "Channel 4 also makes some of its programming available \"on demand\" via cable and the Internet through Channel 4.",
"title": "Carriage"
},
{
"paragraph_id": 41,
"text": "During its first decade, Channel 4 was funded by subscriptions collected by the IBA from the ITV regional companies, in return for which each company had the right to sell advertisements on the fourth channel in its own region and keep the proceeds. This meant that ITV and Channel 4 were not in competition with each other, and often promoted each other's programmes.",
"title": "Funding"
},
{
"paragraph_id": 42,
"text": "A change in funding came about under the Broadcasting Act 1990 when the new corporation was afforded the ability to fund itself. Originally this arrangement left a \"safety net\" guaranteed minimum income should the revenue fall too low, funded by large insurance payments made to the ITV companies. Such a subsidy was never required, however, and these premiums were phased out by the government in 1998. After the link with ITV was cut, the cross-promotion which had existed between ITV and Channel 4 also ended.",
"title": "Funding"
},
{
"paragraph_id": 43,
"text": "In 2007, owing to severe funding difficulties, the channel sought government help and was granted a payment of £14 million over a six-year period. The money was to have come from the television licence fee, and would have been the first time that money from the licence fee had been given to any broadcaster other than the BBC. However, the plan was scrapped by the Secretary of State for Culture, Media and Sport, Andy Burnham, ahead of \"broader decisions about the future framework of public service broadcasting\". The broadcasting regulator Ofcom released its review in January 2009 in which it suggested that Channel 4 would preferably be funded by \"partnerships, joint ventures or mergers\".",
"title": "Funding"
},
{
"paragraph_id": 44,
"text": "As of 2022, it breaks even in much the same way as most privately run commercial stations through the sale of on-air advertising, programme sponsorship, and the sale of any programme content and merchandising rights it owns, such as overseas broadcasting rights and domestic video sales. For example, as of 2012 its total revenues were £925 million with 91 per cent derived from sale of advertising. It also has the ability to subsidise the main network through any profits made on the corporation's other endeavours, which have in the past included subscription fees from stations such as E4 and Film4 (now no longer subscription services) and its \"video-on-demand\" sales. In practice, however, these other activities are loss-making, and are subsidised by the main network. According to Channel 4's last published accounts, for 2005, the extent of this cross-subsidy was some £30 million.",
"title": "Funding"
},
{
"paragraph_id": 45,
"text": "Channel 4 is a \"publisher-broadcaster\", meaning that it commissions or \"buys\" all of its programming from companies independent of itself. It was the first UK broadcaster to do so on a significant scale; such commissioning is a stipulation which is included in its licence to broadcast. In consequence, numerous independent production companies emerged, though external commissioning on the BBC and in ITV (where a quota of 25 per cent minimum of total output has been imposed since the Broadcasting Act 1990 came into force) has become regular practice, as well as on the numerous stations that launched later. Although it was the first British broadcaster to commission all of its programmes from third parties, Channel 4 was the last terrestrial broadcaster to outsource its transmission and playout operations (to Red Bee Media), after 25 years in-house.",
"title": "Programming"
},
{
"paragraph_id": 46,
"text": "The requirement to obtain all content externally is stipulated in its licence. Additionally, Channel 4 also began a trend of owning the copyright and distribution rights of the programmes it aired, in a manner that is similar to the major Hollywood studios' ownership of television programmes that they did not directly produce. Thus, although Channel 4 does not produce programmes, many are seen as belonging to it.",
"title": "Programming"
},
{
"paragraph_id": 47,
"text": "It was established with a specific intention of providing programming to groups of minority interests, not catered for by its competitors, which at the time were only the BBC and ITV.",
"title": "Programming"
},
{
"paragraph_id": 48,
"text": "Channel 4 also pioneered the concept of 'stranded programming', where seasons of programmes following a common theme would be aired and promoted together. Some would be very specific, and run for a fixed period of time; the 4 Mation season, for example, showed innovative animation. Other, less specific strands, were (and still are) run regularly, such as T4, a strand of programming aimed at teenagers, on weekend mornings (and weekdays during school/college holidays); Friday Night Comedy, a slot where the channel would pioneer its style of comedy commissions, 4Music (now a separate channel) and 4Later, an eclectic collection of offbeat programmes transmitted in the early hours of the morning.",
"title": "Programming"
},
{
"paragraph_id": 49,
"text": "For a period in the mid-1980s, some art-house films (dubbed by Channel 4's critics as being pornographic) would be screened with a red triangle graphic in the upper right of the screen.",
"title": "Programming"
},
{
"paragraph_id": 50,
"text": "In recent years concerns have arisen regarding a number of programmes made for Channel 4, that are believed missing from all known archives.",
"title": "Programming"
},
{
"paragraph_id": 51,
"text": "The following is a list of the 10 most watched shows on Channel 4 since launch, based on Live +28 data supplied by BARB, and archival data published by Channel 4.",
"title": "Programming"
},
{
"paragraph_id": 52,
"text": "During the station's early days, the screenings of innovative short one-off comedy films produced by a rotating line-up of alternative comedians went under the title of The Comic Strip Presents. The Tube and Saturday Live/Friday Night Live also launched the careers of a number of comedians and writers. Channel 4 broadcast a number of popular American imports, including The Cosby Show, Roseanne, Home Improvement, Friends, Sex and the City, South Park and Will & Grace. Other significant US acquisitions include The Simpsons, for which the station was reported to have paid £700,000 per episode for the terrestrial television rights.",
"title": "Programming"
},
{
"paragraph_id": 53,
"text": "In April 2010, Channel 4 became the first UK broadcaster to adapt the American comedy institution of roasting to British television, with A Comedy Roast.",
"title": "Programming"
},
{
"paragraph_id": 54,
"text": "In 2010, Channel 4 organised Channel 4's Comedy Gala, a comedy benefit show in aid of Great Ormond Street Children's Hospital. With over 25 comedians appearing, it billed it as \"the biggest live stand up show in United Kingdom history\". Filmed live on 30 March in front of 14,000 at The O2 Arena in London, it was broadcast on 5 April. This has continued to 2016.",
"title": "Programming"
},
{
"paragraph_id": 55,
"text": "In 2021, Channel 4 decided to revive The British Comedy Awards as part of their Stand Up To Cancer programming. The ceremony, billed as The National Comedy Awards was due to be held in the spring of 2021 but was delayed due to the Coronavirus pandemic until 15 December 2021 and then cancelled a week before it was due to be held, due to concerns over the Omicron variant. The ceremony was finally held on 2 March 2022 and broadcast on Channel 4 three days later. The National Comedy Awards was not the only live comedy event that was part of the channel's Christmas schedule that was effected by these concerns as Joe Lycett: Mummy's Big Christmas Do! was also postponed, with the 22 December show due to air as a pilot for a new series called Mummy's House Party in spring 2022. Lycett's Birmingham-based extravaganza finally made it to air on 3 July 2022 as Joe Lycett's Big Pride Party, with 0.29 million viewers tuning in (compared to 0.69 million for The Cruise on Channel 5).",
"title": "Programming"
},
{
"paragraph_id": 56,
"text": "Channel 4 has a strong reputation for history programmes and documentaries. Its news service, Channel 4 News, is supplied by ITN whilst its long-standing investigative documentary series, Dispatches, gains attention from other media outlets. Its live broadcast of the first public autopsy in the UK for 170 years, carried out by Gunther von Hagens in 2002 and the 2003 one-off stunt Derren Brown Plays Russian Roulette Live proved controversial.",
"title": "Programming"
},
{
"paragraph_id": 57,
"text": "A season of television programmes about masturbation, called Wank Week, was to be broadcast in the United Kingdom by Channel 4 in March 2007. The series came under public attack from senior television figures, and was pulled amid claims of declining editorial standards and concern for the channel's public service broadcasting credentials.",
"title": "Programming"
},
{
"paragraph_id": 58,
"text": "FourDocs was an online documentary site provided by Channel 4. It allowed viewers to upload their own documentaries to the site for others to view. It focused on documentaries of between 3 and 5 minutes. The website also included an archive of classic documentaries, interviews with documentary filmmakers and short educational guides to documentary-making. It won a Peabody Award in 2006. The site also included a strand for documentaries of under 59 seconds, called \"Microdocs\".",
"title": "Programming"
},
{
"paragraph_id": 59,
"text": "Channel 4 is obliged to carry schools programming as part of its remit and licence.",
"title": "Programming"
},
{
"paragraph_id": 60,
"text": "Since 1957 ITV had produced schools programming, which became an obligation. In 1987, five years after the station was launched, the IBA afforded ITV free carriage of these programmes during Channel 4's then-unused weekday morning hours. This arrangement allowed the ITV companies to fulfil their obligation to provide schools programming, whilst allowing ITV itself to broadcast regular programmes complete with advertisements. During the times in which schools programmes were aired Central Television provided most of the continuity with play-out originating from Birmingham.",
"title": "Programming"
},
{
"paragraph_id": 61,
"text": "After the restructuring of the station in 1993, ITV's obligations to provide such programming on Channel 4's airtime passed to Channel 4 itself, and the new service became Channel 4 Schools, with the new corporation administering the service and commissioning its programmes, some still from ITV, others from independent producers.",
"title": "Programming"
},
{
"paragraph_id": 62,
"text": "In March 2008, the 4Learning interactive new media commission Slabovia.tv was launched. The Slabplayer online media player showing TV shows for teenagers was launched on 26 May 2008.",
"title": "Programming"
},
{
"paragraph_id": 63,
"text": "The schools programming has always had elements which differ from its normal presentational package. In 1993, the Channel 4 Schools idents featured famous people in one category, with light shining on them in front of an industrial-looking setting supplemented by instrumental calming music. This changed in 1996 with the circles look to numerous children touching the screen, forming circles of information then picked up by other children. The last child would produce the Channel 4 logo in the form of three vertical circles, with another in the middle and to the left containing the Channel 4 logo.",
"title": "Programming"
},
{
"paragraph_id": 64,
"text": "A present feature of presentation was a countdown sequence featuring, in 1993 a slide with the programme name, and afterwards an extended sequence matching the channel branding. In 1996, this was an extended ident with timer in top left corner, and in 1999 following the adoption of the squares look, featured a square with timer slowly make its way across the right of the screen with people learning and having fun while doing so passing across the screen. It finished with the Channel 4 logo box on the right of the screen and the name 'Channel 4 Schools' being shown. This was adapted in 2000 when the service's name was changed to '4Learning'.",
"title": "Programming"
},
{
"paragraph_id": 65,
"text": "In 2001, this was altered to various scenes from classrooms around the world and different parts of school life. The countdown now flips over from the top, right, bottom and left with each second, and ends with four coloured squares, three of which are aligned vertically to the left of the Channel 4 logo, which is contained inside the fourth box. The tag 'Learning' is located directly beneath the logo. The final countdown sequence lasted between 2004 and 2005 and featured a background video of current controversial issues, overlaid with upcoming programming information. The video features people in the style of graffiti enacting the overuse of CCTV cameras, fox hunting, computer viruses and pirate videos, relationships, pollution of the seas and violent lifestyles. Following 2005, no branded section has been used for schools programmes.",
"title": "Programming"
},
{
"paragraph_id": 66,
"text": "From the outset, Channel 4 did not conform to the expectations of conventional religious broadcasting in the UK. John Ranelagh, first Commissioning Editor for Religion, made his priority 'broadening the spectrum of religious programming' and more 'intellectual' concerns. He also ignored the religious programme advisory structure that had been put in place by the BBC, and subsequently adopted by ITV. Ranelagh's first major commission caused a furore, a three-part documentary series called Jesus: The Evidence. The programmes, transmitted during the Easter period of 1984, seemed to advocate the idea that the Gospels were unreliable, Jesus may have indulged in witchcraft, and that he may not have even existed. The series triggered a public outcry, and marked a significant moment in the deterioration in the relationship between the UK's broadcasting and religious institutions.",
"title": "Programming"
},
{
"paragraph_id": 67,
"text": "Numerous genres of film-making – such as comedy, drama, documentary, adventure/action, romance and horror/thriller – are represented in the channel's schedule. From the launch of Channel 4 until 1998, film presentations on C4 would often be broadcast under the \"Film on Four\" banner.",
"title": "Programming"
},
{
"paragraph_id": 68,
"text": "In March 2005, Channel 4 screened the uncut Lars von Trier film The Idiots, which includes unsimulated sexual intercourse, making it the first UK terrestrial channel to do so. The channel had previously screened other films with similar material but censored and with warnings.",
"title": "Programming"
},
{
"paragraph_id": 69,
"text": "Since 1 November 1998, Channel 4 has had a digital subsidiary channel dedicated to the screening of films. This channel launched as a paid subscription channel under the name \"FilmFour\", and was relaunched in July 2006 as a free-to-air channel under the current name of \"Film4\". The Film4 channel carries a wide range of film productions, including acquired and Film4-produced projects. Channel 4's general entertainment channels E4 and More4 also screen feature films at certain points in the schedule as part of their content mix.",
"title": "Programming"
},
{
"paragraph_id": 70,
"text": "On 8 March 2007, Channel 4 screened a documentary, The Great Global Warming Swindle stating that global warming is \"a lie\" and \"the biggest scam of modern times\". The programme's accuracy were disputed on multiple points, and commentators criticised it for being one-sided, observing that the mainstream position on global warming is supported by the scientific academies of the major industrialised nations. There were 246 complaints to Ofcom as of 25 April 2007, including allegations that the programme falsified data. The programme was criticised by scientists and scientific organisations, and various scientists who participated in the documentary claimed their views had been distorted.",
"title": "Programming"
},
{
"paragraph_id": 71,
"text": "Against Nature: An earlier controversial Channel 4 programme made by Martin Durkin which was also critical of the environmental movement and was charged by the UK's Independent Television Commission for misrepresenting and distorting the views of interviewees by selective editing.",
"title": "Programming"
},
{
"paragraph_id": 72,
"text": "The Greenhouse Conspiracy: An earlier Channel 4 documentary broadcast on 12 August 1990, as part of the Equinox series, in which similar claims were made. Three of the people interviewed (Lindzen, Michaels and Spencer) were also interviewed in The Great Global Warming Swindle.",
"title": "Programming"
},
{
"paragraph_id": 73,
"text": "In the Alternative Christmas address of 2008, a Channel 4 tradition since 1993 with a different presenter each year, Iranian President Mahmoud Ahmadinejad made a thinly veiled attack on the United States by claiming that Christ would have been against \"bullying, ill-tempered and expansionist powers\".",
"title": "Programming"
},
{
"paragraph_id": 74,
"text": "The broadcast was rebuked by human rights activists, politicians and religious figures, including Peter Tatchell, Louise Ellman, Ron Prosor and Rabbi Aaron Goldstein. A spokeswoman for the Foreign and Commonwealth Office said: \"President Ahmadinejad has, during his time in office, made a series of appalling anti-Semitic statements. The British media are rightly free to make their own editorial choices, but this invitation will cause offence and bemusement not just at home but among friendly countries abroad\".",
"title": "Programming"
},
{
"paragraph_id": 75,
"text": "However, Channel 4 was defended by Stonewall director Ben Summerskill who stated: \"In spite of his ridiculous and often offensive views, it is an important way of reminding him that there are some countries where free speech is not repressed...If it serves that purpose, then Channel 4 will have done a significant public service\". Dorothy Byrne, Channel 4's head of news and current affairs, said in response to the station's critics: \"As the leader of one of the most powerful states in the Middle East, President Ahmadinejad's views are enormously influential... As we approach a critical time in international relations, we are offering our viewers an insight into an alternative world view...Channel 4 has devoted more airtime to examining Iran than any other broadcaster and this message continues a long tradition of offering a different perspective on the world around us\".",
"title": "Programming"
},
{
"paragraph_id": 76,
"text": "4Talent is an editorial branch of Channel 4's commissioning wing, which co-ordinates Channel 4's various talent development schemes for film, television, radio, new media and other platforms and provides a showcasing platform for new talent.",
"title": "Programming"
},
{
"paragraph_id": 77,
"text": "There are bases in London, Birmingham, Glasgow and Belfast, serving editorial hubs known respectively as 4Talent National, 4Talent Central England, 4Talent Scotland and 4Talent Northern Ireland. These four sites include features, profiles and interviews in text, audio and video formats, divided into five zones: TV, Film, Radio, New Media and Extras, which covers other arts such as theatre, music and design. 4Talent also collates networking, showcasing and professional development opportunities, and runs workshops, masterclasses, seminars and showcasing events across the UK.",
"title": "Programming"
},
{
"paragraph_id": 78,
"text": "4Talent Magazine is the creative industries magazine from 4Talent, which launched in 2005 as TEN4 magazine under the editorship of Dan Jones. 4Talent Magazine is currently edited by Nick Carson. Other staff include deputy editor Catherine Bray and production editor Helen Byrne. The magazine covers rising and established figures of interest in the creative industries, a remit including film, radio, TV, comedy, music, new media and design.",
"title": "Programming"
},
{
"paragraph_id": 79,
"text": "Subjects are usually UK-based, with contributing editors based in Northern Ireland, Scotland, London and Birmingham, but the publication has been known to source international content from Australia, America, continental Europe and the Middle East. The magazine is frequently organised around a theme for the issue, for instance giving half of November 2007's pages over to profiling winners of the annual 4Talent Awards.",
"title": "Programming"
},
{
"paragraph_id": 80,
"text": "An unusual feature of the magazine's credits is the equal prominence given to the names of writers, photographers, designers and illustrators, contradicting standard industry practice of more prominent writer bylines. It is also recognisable for its 'wraparound' covers, which use the front and back as a continuous canvas – often produced by guest artists.",
"title": "Programming"
},
{
"paragraph_id": 81,
"text": "Although 4Talent Magazine is technically a newsstand title, a significant proportion of its readers are subscribers. It started life as a quarterly 100-page title, but has since doubled in size and is now published bi-annually.",
"title": "Programming"
},
{
"paragraph_id": 82,
"text": "Since the 2010s, Channel 4 has become the public service broadcaster most likely to amend their schedule at short notice, if programmes are not gaining sufficient viewers in their intended slots. Programmes which have been heavily promoted by the channel before launch and then have lost their slot a week later include Sixteen: Class of 2021. This was a fly-on-the-wall school documentary which lost its prime 9pm slot after one episode on 31 August 2021, even with a 4 star review in The Guardian. Channel 4 moved the next episode to a late night (post-primetime) slot on a different day and continued to broadcast the remainder of the four-part series in this timeslot.",
"title": "Programming"
},
{
"paragraph_id": 83,
"text": "Also in 2021, the channel launched Epic Wales: Valleys, Mountains and Coast, a version of their More4 documentaries The Pennines: Backbone of Britain, The Yorkshire Dales and The Lakes and Devon and Cornwall. set in Wales. Epic Wales: Valleys, Mountains and Coast. was initially broadcast in a prime Friday night slot at 8pm, in the hour before their comedy shows, but was dumped by the channel before the series was completed and replaced by repeats. In February 2022, the channel scheduled a new version of the show under the title Wonderous Wales with a Saturday night slot at 8pm but after one episode, they decided to take this series out of their schedule, moving up a repeat of Matt Baker: Our Farm in the Dales to 8pm and putting an episode of Escape to the Chateau in Baker's slot at 7pm. Other programmes moved out of primetime in 2022, include Mega Mansion Hunters, Channel 4's answer to Selling Sunset, which saw its third and final episode moved past midnight with repeats put in the schedule before it, and Richard Hammond's Crazy Contraptions, a primetime Friday night competitive engineering show which saw its grand final moved to 11pm on a Sunday night. Instead of Hammond's competition, Channel 4 decided to schedule the fifth series of Devon and Cornwall in its place at 8pm on Friday nights, with this documentary being put up against Channel 5's World's Most Scenic Railway Journeys in the same timeslot.",
"title": "Programming"
},
{
"paragraph_id": 84,
"text": "A new series of Unreported World was due to start on 18 February 2022 with a report by Seyi Rhodes in South Sudan, but was dropped due to an extended storm report on Channel 4 News. When the programme was rescheduled for following Fridays, it was dropped again as Channel 4 News was extended due to the 2022 Russian invasion of Ukraine. Winter Paralympics: Today in Beijing is due to take the Unreported World slot from 11 March 2022 though this sports programme may also be moved around the schedule to continue the extended news programmes reporting on the conflict. The invasion of Ukraine has also prompted Channel 4 to acquire and schedule the comedy series Servant of the People as a last minute replacement. The programme stars the current President of Ukraine Volodymyr Zelenskyy as an ordinary man who gets elected to run the country, and will be shown on 6 March 2022 along with the documentary Zelenskyy: The Man Who Took on Putin.",
"title": "Programming"
},
{
"paragraph_id": 85,
"text": "In addition to these shows, O.T. Fagbenle's sitcom Maxxx was pulled from their youth TV channel E4, after one episode from the series had been broadcast on 2 April 2020, with Channel 4 deciding to keep the series off-air until Black History Month, with the series now going out on the main channel from October 2020.",
"title": "Programming"
},
{
"paragraph_id": 86,
"text": "In May 2022, the reality dating show Let's Make a Love Scene was scrapped after one episode with the second programme in the series, hosted by Ellie Taylor, pulled from the May 20 schedule and replaced with an episode of 8 Out of 10 Cats Does Countdown. The first edition was negatively received, with Anita Singh, the Arts and Entertainments Editor for The Telegraph writing that the show was \"the most ill-conceived programme idea since Prince Edward dreamt up It's a Royal Knockout\".",
"title": "Programming"
},
{
"paragraph_id": 87,
"text": "Since its launch in 1982, Channel 4 has used the same logo which consists of a stylised numeral \"4\" made up of nine differently-shaped blocks.",
"title": "Presentation"
},
{
"paragraph_id": 88,
"text": "The original version was designed by Martin Lambie-Nairn and his partner Colin Robinson and was the first UK channel ident made using advanced computer generation (the first electronically-generated ident was on BBC2 in 1979, but this was two-dimensional). It was designed in conjunction with Bo Gehring Aviation of Los Angeles and originally depicted the \"4\" in red, yellow, green, blue and purple. The music accompanying the ident was called \"Fourscore\" and was composed by David Dundas; it was later released as a single alongside a B-side, \"Fourscore Two\", although neither reached the UK charts. In November 1992, \"Fourscore\" was replaced by new music.",
"title": "Presentation"
},
{
"paragraph_id": 89,
"text": "In 1996, Channel 4 commissioned Tomato Films to revamp the \"4\", which resulted in the \"Circles\" idents showing four white circles forming up transparently over various scenes, with the \"4\" logo depicted in white in one of the circles.",
"title": "Presentation"
},
{
"paragraph_id": 90,
"text": "In 1999, Spin redesigned the logo to feature in a single square that sat on the right-hand side of the screen, whilst various stripes would move along from left to right, often lighting the squared \"4\" up. Like previous \"Circles\" idents from 1996 (which was made by Tomato Films), the stripes would be interspersed with various scenes potentially related to the upcoming programme.",
"title": "Presentation"
},
{
"paragraph_id": 91,
"text": "The logo was made three-dimensional again in 2004 when it was depicted in filmed scenes that show the blocks forming the \"4\" logo for less than a second before the action moves away again.",
"title": "Presentation"
},
{
"paragraph_id": 92,
"text": "In 2015, the logo was disassembled completely to allow the blocks to appear as parts of a nature scene, sometimes featuring a strange dancing creature and sometimes being excavated for scientific study, one being studied under a microscope and showing a tardigrade. The second wave of these idents, launched in 2017, depict a giant creature made of the \"4\" blocks (made to look almost like a person) interacting with everyday life, sometimes shouting the \"Fourscore\" theme as a foghorn.",
"title": "Presentation"
},
{
"paragraph_id": 93,
"text": "The original 1982 ident was given a one-off revival on 28 December 2020, as a tribute to Lambie-Nairn after his death three days earlier. It was also used on 22 January 2021 as part of the 80s-themed \"takeover\" to promote the premiere of It's a Sin, which was set during the 1980s AIDS crisis.",
"title": "Presentation"
},
{
"paragraph_id": 94,
"text": "The Channel 4 logo was reassembled in 2023 in an all-lime green colour to promote the network's new digital-first strategy, which included its streaming service All 4 being renamed under the Channel 4 brand. This was then followed by the launch of a new idents package on 14 June 2023.",
"title": "Presentation"
},
{
"paragraph_id": 95,
"text": "Channel 4 has, since its inception, broadcast identical programmes and continuity throughout the United Kingdom (excluding Wales where it did not operate on analogue transmitters). At launch this made it unique, as both the BBC and ITV had long-established traditions of providing regional variations in their programming in different areas of the country. Since the launch of subsequent British television channels, Channel 4 has become typical in its lack of regional programming variations.",
"title": "Regions/international"
},
{
"paragraph_id": 96,
"text": "A few exceptions exist to this rule for programming and continuity:",
"title": "Regions/international"
},
{
"paragraph_id": 97,
"text": "Part of Channel 4's remit covers the commissioning of programmes from outside London. Channel 4 has a dedicated director of nations and regions, Stuart Cosgrove, who is based in a regional office in Glasgow. As his job title suggests, it is his responsibility to foster relations with independent producers based in areas of the United Kingdom (including Wales) outside London.",
"title": "Regions/international"
},
{
"paragraph_id": 98,
"text": "Channel 4 is available in Ireland, with adverts tailored to the Irish market. The channel is registered with the broadcasting regulators in Luxembourg for terms of conduct and business within the EU/EEA while observing guidelines outlined by Ireland's BAI code. Irish advertising sales are managed by Media Link in Dublin. Where Channel 4 does not hold broadcasting rights within the Republic of Ireland such programming is unavailable. For example, the series Glee was not available on Channel 4 on Sky in Ireland due to it broadcasting on TV3 within Ireland. Currently, programming available on Channel 4 is available within the Republic of Ireland without restrictions. Elsewhere in Europe, the UK version of the channel is available.",
"title": "Regions/international"
},
{
"paragraph_id": 99,
"text": "With ITV plc pushing for much looser requirements on the amount of regional news and other programming it is obliged to broadcast in its ITV regions, the idea of Channel 4 taking on a regional news commitment has been considered, with the corporation in talks with Ofcom and ITV over the matter. Channel 4 believe that a scaling-back of such operations on ITV's part would be detrimental to Channel 4's national news operation, which shares much of its resources with ITV through their shared news contractor ITN. At the same time, Channel 4 also believe that such an additional public service commitment would bode well in on-going negotiations with Ofcom in securing additional funding for its other public service commitments.",
"title": "Regions/international"
},
{
"paragraph_id": 100,
"text": "In mid-2006 Channel 4 ran a six-month closed trial of HDTV, as part of the wider Freeview HD experiment via the Crystal Palace transmitter to London and parts of the home counties, including the use of Lost and Desperate Housewives as part of the experiment, as US broadcasters such as ABC already have an HDTV back catalogue.",
"title": "Channel 4 HD"
},
{
"paragraph_id": 101,
"text": "On 10 December 2007, Channel 4 launched a high-definition television simulcast of Channel 4 on Sky's digital satellite platform, after Sky agreed to contribute toward the channel's satellite distribution costs. It was the first full-time high-definition channel from a terrestrial UK broadcaster.",
"title": "Channel 4 HD"
},
{
"paragraph_id": 102,
"text": "On 31 July 2009, Virgin Media added Channel 4 HD on channel 146 (later on channel 142, now on channel 141) as part of the M pack. On 25 March 2010 Channel 4 HD appeared on Freeview channel 52 with a placeholding caption, ahead of a commercial launch on 30 March 2010, coinciding with the commercial launch of Freeview HD. On 19 April 2011, Channel 4 HD was added to Freesat on channel 126. As a consequence, the channel moved from being free-to-view to free-to-air on satellite during March 2011. With the closure of S4C Clirlun in Wales on 1 December 2012, on Freeview, Channel 4 HD launched in Wales on 2 December 2012.",
"title": "Channel 4 HD"
},
{
"paragraph_id": 103,
"text": "The channel carries the same schedule as Channel 4, broadcasting programmes in HD when available, acting as a simulcast. Therefore, SD programming is broadcast upscaled to HD. The first true HD programme to be shown was the 1996 Adam Sandler film Happy Gilmore. From launch until 2016 the presence of the 4HD logo on screen denoted true HD content.",
"title": "Channel 4 HD"
},
{
"paragraph_id": 104,
"text": "On 1 July 2014, Channel 4 +1 HD, an HD simulcast of Channel 4 +1, launched on Freeview channel 110. It closed on 22 June 2020 to help make room on COM7 following the closure of COM8 on Freeview. 4Seven HD were removed from Freeview also.",
"title": "Channel 4 HD"
},
{
"paragraph_id": 105,
"text": "On 20 February 2018, Channel 4 announced that Channel 4 HD and All 4 would no longer be supplied on Freesat from 22 February 2018. Channel 4 HD returned to the platform on 8 December 2021, along with the music channel portfolio of The Box Plus Network.",
"title": "Channel 4 HD"
},
{
"paragraph_id": 106,
"text": "On 27 September 2022, the other 6 advertising regions of Channel 4 (South, Midlands, North, Scotland, Northern Ireland and Rep of Ireland) were made available in HD on Sky and Virgin Media. Prior to this, Channel 4 HD was only available in the London advertising region.",
"title": "Channel 4 HD"
},
{
"paragraph_id": 107,
"text": "Channel 4's video on demand service, known simply as \"Channel 4\" since April 2023, launched in November 2006 as \"4oD\", and was renamed \"All 4\" in March 2015. The service offers a variety of programmes recently shown on Channel 4, E4, More4 or from their archives, though some programmes and movies are not available due to rights issues.",
"title": "Video on demand"
},
{
"paragraph_id": 108,
"text": "Channel 4 originally licensed an ancillary teletext service to provide schedules, programme information and features. The original service was called 4-Tel, and was produced by Intelfax, a company set up especially for the purpose. It was carried in the 400s on Oracle. In 1993, with Oracle losing its franchise to Teletext Ltd, 4-Tel found a new home in the 300s, and had its name shown in the header row. Intelfax continued to produce the service and in 2002 it was renamed FourText.",
"title": "Teletext services"
},
{
"paragraph_id": 109,
"text": "In 2003, Channel 4 awarded Teletext Ltd a ten-year contract to run the channel's ancillary teletext service, named Teletext on 4. The service closed in 2008, and Teletext is no longer available on Channel 4, ITV and Channel 5.",
"title": "Teletext services"
}
] | Channel 4 is a British free-to-air public broadcast television channel owned and operated by Channel Four Television Corporation. It is publicly owned but, unlike the BBC, it receives no public funding and is funded entirely by its commercial activities, including publicity. It began its transmission in 1982 and was established to provide a fourth television service in the United Kingdom. At the time, the only other channels were the licence-funded BBC1 and BBC2, and a single commercial broadcasting network ITV. Originally a subsidiary of the Independent Broadcasting Authority (IBA), the station is now owned and operated by Channel Four Television Corporation, a public corporation of the Department for Culture, Media and Sport, which was established in 1990 and came into operation in 1993. Until 2010, Channel 4 did not broadcast in Wales, but many of its programmes were re-broadcast there by the Welsh fourth channel S4C. In 2010, Channel 4 extended service into Wales and became a nationwide television channel. The network's headquarters are in London and Leeds, with creative hubs in Glasgow and Bristol. | 2001-09-11T10:12:49Z | 2023-12-22T15:11:13Z | [
"Template:Cite press release",
"Template:Cite journal",
"Template:Dead link",
"Template:For timeline",
"Template:Blockquote",
"Template:Overly detailed",
"Template:Multiple image",
"Template:Notelist",
"Template:Authority control",
"Template:Use dmy dates",
"Template:As of",
"Template:Reflist",
"Template:Cite book",
"Template:Official website",
"Template:About",
"Template:Cite news",
"Template:Cbignore",
"Template:Use British English",
"Template:Cite web",
"Template:Channel Four Television Corporation",
"Template:Nom",
"Template:See also",
"Template:International Emmy Founders Award",
"Template:Citation needed",
"Template:Redirect",
"Template:Infobox television channel",
"Template:Main",
"Template:Navboxes",
"Template:Short description"
] | https://en.wikipedia.org/wiki/Channel_4 |
6,322 | Carolina parakeet | The Carolina parakeet (Conuropsis carolinensis), or Carolina conure, is an extinct species of small green neotropical parrot with a bright yellow head, reddish orange face, and pale beak that was native to the Eastern, Midwest, and Plains states of the United States. It was the only indigenous parrot within its range, as well as one of only three parrot species native to the United States (the others being the thick-billed parrot, now extirpated, and the green parakeet, still present in Texas; a fourth parrot species, the red-crowned amazon, is debated). It was called puzzi la née ("head of yellow") or pot pot chee by the Seminole and kelinky in Chickasaw. Though formerly prevalent within its range, the bird had become rare by the middle of the 19th century. The last confirmed sighting in the wild was of the C. c. ludovicianus subspecies in 1910. The last known specimen, a male named Incas, perished in captivity at the Cincinnati Zoo in 1918, and the species was declared extinct in 1939.
The earliest reference to these parrots was in 1583 in Florida reported by Sir George Peckham in A True Report of the Late Discoveries of the Newfound Lands of expeditions conducted by English explorer Sir Humphrey Gilbert, who notes that explorers in North America "doe testifie that they have found in those countryes; ... parrots." They were first scientifically described in English naturalist Mark Catesby's two-volume Natural History of Carolina, Florida and the Bahama Islands published in London in 1731 and 1743.
Carolina parakeets were probably poisonous—French-American naturalist and painter John J. Audubon noted that cats apparently died from eating them, and they are known to have eaten the toxic seeds of cockleburs.
Carolinensis is a species of the genus Conuropsis, one of numerous genera of New World Neotropical parrots in family Psittacidae of true parrots.
The binomial Psittacus carolinensis was assigned by Swedish zoologist Carl Linnaeus in the 10th edition of Systema Naturae published in 1758. The species was given its own genus, Conuropsis, by Italian zoologist and ornithologist Tommaso Salvadori in 1891 in his Catalogue of the Birds in the British Museum, volume 20. The name is derived from the Greek-ified conure ("parrot of the genus Conurus" an obsolete name of genus Aratinga) + -opsis ("likeness of") and Latinized Carolina (from Carolana, an English colonial province) + -ensis (of or "from a place"), therefore a bird "like a conure from Carolina."
Two subspecies are recognized: The Louisiana subspecies of the Carolina parakeet, C. c. ludovicianus, was slightly different in color from the nominate subspecies, being more bluish-green and generally of a somewhat subdued coloration, and became extinct in much the same way, but at a somewhat earlier date (early 1910s). The Appalachian Mountains separated these birds from the eastern C. c. carolinensis.
According to a study of mitochondrial DNA recovered from museum specimens, their closest living relatives include some of the South American Aratinga parakeets: The Nanday parakeet, the sun parakeet, and the golden-capped parakeet. The authors note the bright yellow and orange plumage and blue wing feathers found in C. carolinensis are traits shared by another species, the jandaya parakeet (A. jandaya), that was not sampled in the study, but is generally thought to be closely related. To help resolve the divergence time a whole genome of a preserved specimen has now been sequenced. The Carolina parakeet colonized North America about 5.5 million years ago. This was well before North America and South America were joined by the formation of the Panama land bridge about 3.5 mya. Since the Carolina parakeets' more distant relations are geographically closer to its own historic range while its closest relatives are more geographically distant to it, these data are consistent with the generally accepted hypothesis that Central and North America were colonized at different times by distinct lineages of parrots – parrots that originally invaded South America from Antarctica some time after the breakup of Gondwana, where Neotropical parrots originated approximately 50 mya.
The following cladogram shows the placement of the Carolina parakeet among its closest relatives, after a DNA study by Kirchman et al. (2012):
A fossil parrot, designated Conuropsis fratercula, was described based on a single humerus from the Miocene Sheep Creek Formation (possibly late Hemingfordian, c. 16 mya, possibly later) of Snake River, Nebraska. It was a smaller bird, three-quarters the size of the Carolina parakeet. "The present species is of peculiar interest as it represents the first known parrot-like bird to be described as a fossil from North America." (Wetmore 1926; italics added) However, it is not completely certain that the species is correctly assigned to Conuropsis, but some authors consider it a paleosubspecies of the Carolina parakeet.
The Carolina parakeet was a small, green parrot very similar in size and coloration to the extant jenday parakeet and sun conure - the sun conure being its closest living relative. The majority of the plumage was green with lighter green underparts, a bright yellow head and orange forehead and face extending to behind the eyes and upper cheeks (lores). The shoulders were yellow, continuing down the outer edge of the wings. The primary feathers were mostly green, but with yellow edges on the outer primaries. Thighs were green towards the top and yellow towards the feet. Male and female adults were identical in plumage, however males were slightly larger than females (sexually dimorphic). The legs and feet were light brown. They share the zygodactyl feet of the parrot family. The skin around the eyes was white and the beak was pale flesh colored. These birds weigh about 3.5 oz., are 13 in. long, and have wingspans of 21–23 in.
Young Carolina parakeets differed slightly in coloration from adults. The face and entire body were green, with paler underparts. They lacked yellow or orange plumage on the face, wings, and thighs. Hatchlings were covered in mouse-gray down, until about 39–40 days old, when green wings and tails appeared. Fledglings had full adult plumage around 1 year of age.
These birds were fairly long-lived, at least in captivity; a pair was kept at the Cincinnati Zoo for over 35 years.
The Carolina parakeet had the northernmost range of any known parrot. It was found from southern New York and Wisconsin to Kentucky, Tennessee, and the Gulf of Mexico, from the Atlantic Seaboard to as far west as eastern Colorado. It lived in old-growth forests along rivers and in swamps. Its range was described by early explorers thus: the 43rd parallel as the northern limit, the 26th as the most southern, the 73rd and 106th meridians as the eastern and western boundaries, respectively, the range included all or portions of at least 28 states. Its habitats were old-growth wetland forests along rivers and in swamps, especially in the Mississippi-Missouri drainage basin with large hollow trees including cypress and sycamore to use as roosting and nesting sites.
Only very rough estimates of the birds' former prevalence can be made, with an estimated range of 20,000 to 2.5 million km, and population density of 0.5 to 2.0 parrots per km, population estimates range from tens of thousands to a few million birds (though the densest populations occurred in Florida covering 170,000 km, so hundreds of thousands of the birds may have been in that state alone).
The species may have appeared as a very rare vagrant in places as far north as southern Ontario in Canada. A few bones, including a pygostyle found at the Calvert Site in southern Ontario, came from the Carolina parakeet. The possibility remains open that this specimen was taken there for ceremonial purposes.
The bird lived in huge, noisy flocks of as many as 300 birds. It built its nest in a hollow tree, laying two to five (most accounts say two) 1.6 in (4.1 cm) round white eggs. Reportedly, multiple female parakeets could deposit their eggs into one nest, similar to nesting behavior described in the monk parakeet (Myiopsitta monachus).
It mostly ate the seeds of forest trees and shrubs, including those of cypress, hackberry, beech, sycamore, elm, pine, maple, oak, and other plants such as thistles and sandspurs (Cenchrus species). It also ate fruits, including apples, grapes, and figs (often from orchards by the time of its decline), as well as flower buds, and occasionally, insects. It was especially noted for its predilection for cockleburs (Xanthium strumarium), a plant which contains a toxic glucoside, and it was considered to be an agricultural pest of grain crops.
The last captive Carolina parakeet, Incas, died at the Cincinnati Zoo on February 21, 1918, in the same cage as Martha, the last passenger pigeon, which died in 1914. There are no scientific studies or surveys of this bird by American naturalists; most information about it is from anecdotal accounts and museum specimens, so details of its prevalence and decline are unverified or speculative.
Extensive accounts of the precolonial and early colonial have been given for prevalence of this bird. The existence of flocks of gregarious, very colorful and raucous parrots could hardly have gone unnoted by European explorers, as parrots were virtually unknown in seafaring European nations in the 16th and 17th centuries. Later accounts in the latter half of the 19th century onward noted the birds' sparseness and absence.
Genetic evidence suggests that while populations had been in decline since the last glacial maximum, the lack of evidence of inbreeding suggests that the birds declined very quickly.
The birds' range collapsed from east to west with settlement and clearing of the eastern and southern deciduous forests. John J. Audubon commented as early as 1832 on the decline of the birds. The bird was rarely reported outside Florida after 1860. The last reported sighting east of the Mississippi River (except Florida) was in 1878 in Kentucky. By the turn of the century, it was restricted to the swamps of central Florida. The last known wild specimen was killed in Okeechobee County, Florida, in 1904, and the last captive bird died at the Cincinnati Zoo on February 21, 1918. This was the male specimen, Incas, that died within a year of his mate, Lady Jane. Additional reports of the bird were made in Okeechobee County, Florida, until the late 1920s, but these are not supported by specimens. Not until 1939, however, did the American Ornithologists' Union declare the Carolina parakeet to be extinct. The IUCN has listed the species as extinct since 1920.
In 1937, three parakeets resembling this species were sighted and filmed in the Okefenokee Swamp of Georgia. However, the American Ornithologists' Union analyzed the film and concluded that they had probably filmed feral parakeets. A year later, in 1938, a flock of parakeets was apparently sighted by a group of experienced ornithologists in the swamps of the Santee River basin in South Carolina, but this sighting was doubted by most other ornithologists. The birds were never seen again after this sighting, and shortly after a portion of the area was destroyed to make way for power lines, making the species' continued existence unlikely.
About 720 skins and 16 skeletons are housed in museums around the world, and analyzable DNA has been extracted from them.
The evidence is indicative that humans had at least a contributory role in the extinction of the Carolina parakeet, through a variety of means. Chief was deforestation in the 18th and 19th centuries. Hunting played a significant role, both for decorative use of their colorful feathers, for example, adornment of women's hats, and for reduction of crop predation. This was partially offset by the recognition of their value in controlling invasive cockleburs. Minor roles were played by capture for the pet trade and, as noted in Pacific Standard, by the introduction for crop pollination of European honeybees that competed for nest sites.
A factor that exacerbated their decline to extinction was the flocking behavior that led them to return to the vicinity of dead and dying birds (e.g., birds downed by hunting), enabling wholesale slaughter.
The final extinction of the species in the early years of the 20th century is somewhat of a mystery, as it happened so rapidly. Vigorous flocks with many juveniles and reproducing pairs were noted as late as 1896, and the birds were long-lived in captivity, but they had virtually disappeared by 1904. Sufficient nest sites remained intact, so deforestation was not the final cause. American ornithologist Noel F. Snyder speculates that the most likely cause seems to be that the birds succumbed to poultry disease, although no recent or historical records exist of New World parrot populations being afflicted by domestic poultry diseases. The modern poultry scourge Newcastle disease was not detected until 1926 in Indonesia, and only a subacute form of it was reported in the United States in 1938. As well, genetic research on samples did not show any significant presence of bird viruses (though this does not solely rule out disease). | [
{
"paragraph_id": 0,
"text": "The Carolina parakeet (Conuropsis carolinensis), or Carolina conure, is an extinct species of small green neotropical parrot with a bright yellow head, reddish orange face, and pale beak that was native to the Eastern, Midwest, and Plains states of the United States. It was the only indigenous parrot within its range, as well as one of only three parrot species native to the United States (the others being the thick-billed parrot, now extirpated, and the green parakeet, still present in Texas; a fourth parrot species, the red-crowned amazon, is debated). It was called puzzi la née (\"head of yellow\") or pot pot chee by the Seminole and kelinky in Chickasaw. Though formerly prevalent within its range, the bird had become rare by the middle of the 19th century. The last confirmed sighting in the wild was of the C. c. ludovicianus subspecies in 1910. The last known specimen, a male named Incas, perished in captivity at the Cincinnati Zoo in 1918, and the species was declared extinct in 1939.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The earliest reference to these parrots was in 1583 in Florida reported by Sir George Peckham in A True Report of the Late Discoveries of the Newfound Lands of expeditions conducted by English explorer Sir Humphrey Gilbert, who notes that explorers in North America \"doe testifie that they have found in those countryes; ... parrots.\" They were first scientifically described in English naturalist Mark Catesby's two-volume Natural History of Carolina, Florida and the Bahama Islands published in London in 1731 and 1743.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Carolina parakeets were probably poisonous—French-American naturalist and painter John J. Audubon noted that cats apparently died from eating them, and they are known to have eaten the toxic seeds of cockleburs.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Carolinensis is a species of the genus Conuropsis, one of numerous genera of New World Neotropical parrots in family Psittacidae of true parrots.",
"title": "Taxonomy"
},
{
"paragraph_id": 4,
"text": "The binomial Psittacus carolinensis was assigned by Swedish zoologist Carl Linnaeus in the 10th edition of Systema Naturae published in 1758. The species was given its own genus, Conuropsis, by Italian zoologist and ornithologist Tommaso Salvadori in 1891 in his Catalogue of the Birds in the British Museum, volume 20. The name is derived from the Greek-ified conure (\"parrot of the genus Conurus\" an obsolete name of genus Aratinga) + -opsis (\"likeness of\") and Latinized Carolina (from Carolana, an English colonial province) + -ensis (of or \"from a place\"), therefore a bird \"like a conure from Carolina.\"",
"title": "Taxonomy"
},
{
"paragraph_id": 5,
"text": "Two subspecies are recognized: The Louisiana subspecies of the Carolina parakeet, C. c. ludovicianus, was slightly different in color from the nominate subspecies, being more bluish-green and generally of a somewhat subdued coloration, and became extinct in much the same way, but at a somewhat earlier date (early 1910s). The Appalachian Mountains separated these birds from the eastern C. c. carolinensis.",
"title": "Taxonomy"
},
{
"paragraph_id": 6,
"text": "According to a study of mitochondrial DNA recovered from museum specimens, their closest living relatives include some of the South American Aratinga parakeets: The Nanday parakeet, the sun parakeet, and the golden-capped parakeet. The authors note the bright yellow and orange plumage and blue wing feathers found in C. carolinensis are traits shared by another species, the jandaya parakeet (A. jandaya), that was not sampled in the study, but is generally thought to be closely related. To help resolve the divergence time a whole genome of a preserved specimen has now been sequenced. The Carolina parakeet colonized North America about 5.5 million years ago. This was well before North America and South America were joined by the formation of the Panama land bridge about 3.5 mya. Since the Carolina parakeets' more distant relations are geographically closer to its own historic range while its closest relatives are more geographically distant to it, these data are consistent with the generally accepted hypothesis that Central and North America were colonized at different times by distinct lineages of parrots – parrots that originally invaded South America from Antarctica some time after the breakup of Gondwana, where Neotropical parrots originated approximately 50 mya.",
"title": "Taxonomy"
},
{
"paragraph_id": 7,
"text": "The following cladogram shows the placement of the Carolina parakeet among its closest relatives, after a DNA study by Kirchman et al. (2012):",
"title": "Taxonomy"
},
{
"paragraph_id": 8,
"text": "A fossil parrot, designated Conuropsis fratercula, was described based on a single humerus from the Miocene Sheep Creek Formation (possibly late Hemingfordian, c. 16 mya, possibly later) of Snake River, Nebraska. It was a smaller bird, three-quarters the size of the Carolina parakeet. \"The present species is of peculiar interest as it represents the first known parrot-like bird to be described as a fossil from North America.\" (Wetmore 1926; italics added) However, it is not completely certain that the species is correctly assigned to Conuropsis, but some authors consider it a paleosubspecies of the Carolina parakeet.",
"title": "Taxonomy"
},
{
"paragraph_id": 9,
"text": "The Carolina parakeet was a small, green parrot very similar in size and coloration to the extant jenday parakeet and sun conure - the sun conure being its closest living relative. The majority of the plumage was green with lighter green underparts, a bright yellow head and orange forehead and face extending to behind the eyes and upper cheeks (lores). The shoulders were yellow, continuing down the outer edge of the wings. The primary feathers were mostly green, but with yellow edges on the outer primaries. Thighs were green towards the top and yellow towards the feet. Male and female adults were identical in plumage, however males were slightly larger than females (sexually dimorphic). The legs and feet were light brown. They share the zygodactyl feet of the parrot family. The skin around the eyes was white and the beak was pale flesh colored. These birds weigh about 3.5 oz., are 13 in. long, and have wingspans of 21–23 in.",
"title": "Description"
},
{
"paragraph_id": 10,
"text": "Young Carolina parakeets differed slightly in coloration from adults. The face and entire body were green, with paler underparts. They lacked yellow or orange plumage on the face, wings, and thighs. Hatchlings were covered in mouse-gray down, until about 39–40 days old, when green wings and tails appeared. Fledglings had full adult plumage around 1 year of age.",
"title": "Description"
},
{
"paragraph_id": 11,
"text": "These birds were fairly long-lived, at least in captivity; a pair was kept at the Cincinnati Zoo for over 35 years.",
"title": "Description"
},
{
"paragraph_id": 12,
"text": "The Carolina parakeet had the northernmost range of any known parrot. It was found from southern New York and Wisconsin to Kentucky, Tennessee, and the Gulf of Mexico, from the Atlantic Seaboard to as far west as eastern Colorado. It lived in old-growth forests along rivers and in swamps. Its range was described by early explorers thus: the 43rd parallel as the northern limit, the 26th as the most southern, the 73rd and 106th meridians as the eastern and western boundaries, respectively, the range included all or portions of at least 28 states. Its habitats were old-growth wetland forests along rivers and in swamps, especially in the Mississippi-Missouri drainage basin with large hollow trees including cypress and sycamore to use as roosting and nesting sites.",
"title": "Distribution and habitat"
},
{
"paragraph_id": 13,
"text": "Only very rough estimates of the birds' former prevalence can be made, with an estimated range of 20,000 to 2.5 million km, and population density of 0.5 to 2.0 parrots per km, population estimates range from tens of thousands to a few million birds (though the densest populations occurred in Florida covering 170,000 km, so hundreds of thousands of the birds may have been in that state alone).",
"title": "Distribution and habitat"
},
{
"paragraph_id": 14,
"text": "The species may have appeared as a very rare vagrant in places as far north as southern Ontario in Canada. A few bones, including a pygostyle found at the Calvert Site in southern Ontario, came from the Carolina parakeet. The possibility remains open that this specimen was taken there for ceremonial purposes.",
"title": "Distribution and habitat"
},
{
"paragraph_id": 15,
"text": "The bird lived in huge, noisy flocks of as many as 300 birds. It built its nest in a hollow tree, laying two to five (most accounts say two) 1.6 in (4.1 cm) round white eggs. Reportedly, multiple female parakeets could deposit their eggs into one nest, similar to nesting behavior described in the monk parakeet (Myiopsitta monachus).",
"title": "Behavior and diet"
},
{
"paragraph_id": 16,
"text": "It mostly ate the seeds of forest trees and shrubs, including those of cypress, hackberry, beech, sycamore, elm, pine, maple, oak, and other plants such as thistles and sandspurs (Cenchrus species). It also ate fruits, including apples, grapes, and figs (often from orchards by the time of its decline), as well as flower buds, and occasionally, insects. It was especially noted for its predilection for cockleburs (Xanthium strumarium), a plant which contains a toxic glucoside, and it was considered to be an agricultural pest of grain crops.",
"title": "Behavior and diet"
},
{
"paragraph_id": 17,
"text": "The last captive Carolina parakeet, Incas, died at the Cincinnati Zoo on February 21, 1918, in the same cage as Martha, the last passenger pigeon, which died in 1914. There are no scientific studies or surveys of this bird by American naturalists; most information about it is from anecdotal accounts and museum specimens, so details of its prevalence and decline are unverified or speculative.",
"title": "Extinction"
},
{
"paragraph_id": 18,
"text": "Extensive accounts of the precolonial and early colonial have been given for prevalence of this bird. The existence of flocks of gregarious, very colorful and raucous parrots could hardly have gone unnoted by European explorers, as parrots were virtually unknown in seafaring European nations in the 16th and 17th centuries. Later accounts in the latter half of the 19th century onward noted the birds' sparseness and absence.",
"title": "Extinction"
},
{
"paragraph_id": 19,
"text": "Genetic evidence suggests that while populations had been in decline since the last glacial maximum, the lack of evidence of inbreeding suggests that the birds declined very quickly.",
"title": "Extinction"
},
{
"paragraph_id": 20,
"text": "The birds' range collapsed from east to west with settlement and clearing of the eastern and southern deciduous forests. John J. Audubon commented as early as 1832 on the decline of the birds. The bird was rarely reported outside Florida after 1860. The last reported sighting east of the Mississippi River (except Florida) was in 1878 in Kentucky. By the turn of the century, it was restricted to the swamps of central Florida. The last known wild specimen was killed in Okeechobee County, Florida, in 1904, and the last captive bird died at the Cincinnati Zoo on February 21, 1918. This was the male specimen, Incas, that died within a year of his mate, Lady Jane. Additional reports of the bird were made in Okeechobee County, Florida, until the late 1920s, but these are not supported by specimens. Not until 1939, however, did the American Ornithologists' Union declare the Carolina parakeet to be extinct. The IUCN has listed the species as extinct since 1920.",
"title": "Extinction"
},
{
"paragraph_id": 21,
"text": "In 1937, three parakeets resembling this species were sighted and filmed in the Okefenokee Swamp of Georgia. However, the American Ornithologists' Union analyzed the film and concluded that they had probably filmed feral parakeets. A year later, in 1938, a flock of parakeets was apparently sighted by a group of experienced ornithologists in the swamps of the Santee River basin in South Carolina, but this sighting was doubted by most other ornithologists. The birds were never seen again after this sighting, and shortly after a portion of the area was destroyed to make way for power lines, making the species' continued existence unlikely.",
"title": "Extinction"
},
{
"paragraph_id": 22,
"text": "About 720 skins and 16 skeletons are housed in museums around the world, and analyzable DNA has been extracted from them.",
"title": "Extinction"
},
{
"paragraph_id": 23,
"text": "The evidence is indicative that humans had at least a contributory role in the extinction of the Carolina parakeet, through a variety of means. Chief was deforestation in the 18th and 19th centuries. Hunting played a significant role, both for decorative use of their colorful feathers, for example, adornment of women's hats, and for reduction of crop predation. This was partially offset by the recognition of their value in controlling invasive cockleburs. Minor roles were played by capture for the pet trade and, as noted in Pacific Standard, by the introduction for crop pollination of European honeybees that competed for nest sites.",
"title": "Extinction"
},
{
"paragraph_id": 24,
"text": "A factor that exacerbated their decline to extinction was the flocking behavior that led them to return to the vicinity of dead and dying birds (e.g., birds downed by hunting), enabling wholesale slaughter.",
"title": "Extinction"
},
{
"paragraph_id": 25,
"text": "The final extinction of the species in the early years of the 20th century is somewhat of a mystery, as it happened so rapidly. Vigorous flocks with many juveniles and reproducing pairs were noted as late as 1896, and the birds were long-lived in captivity, but they had virtually disappeared by 1904. Sufficient nest sites remained intact, so deforestation was not the final cause. American ornithologist Noel F. Snyder speculates that the most likely cause seems to be that the birds succumbed to poultry disease, although no recent or historical records exist of New World parrot populations being afflicted by domestic poultry diseases. The modern poultry scourge Newcastle disease was not detected until 1926 in Indonesia, and only a subacute form of it was reported in the United States in 1938. As well, genetic research on samples did not show any significant presence of bird viruses (though this does not solely rule out disease).",
"title": "Extinction"
}
] | The Carolina parakeet, or Carolina conure, is an extinct species of small green neotropical parrot with a bright yellow head, reddish orange face, and pale beak that was native to the Eastern, Midwest, and Plains states of the United States. It was the only indigenous parrot within its range, as well as one of only three parrot species native to the United States. It was called puzzi la née or pot pot chee by the Seminole and kelinky in Chickasaw. Though formerly prevalent within its range, the bird had become rare by the middle of the 19th century. The last confirmed sighting in the wild was of the C. c. ludovicianus subspecies in 1910. The last known specimen, a male named Incas, perished in captivity at the Cincinnati Zoo in 1918, and the species was declared extinct in 1939. The earliest reference to these parrots was in 1583 in Florida reported by Sir George Peckham in A True Report of the Late Discoveries of the Newfound Lands of expeditions conducted by English explorer Sir Humphrey Gilbert, who notes that explorers in North America "doe testifie that they have found in those countryes; ... parrots." They were first scientifically described in English naturalist Mark Catesby's two-volume Natural History of Carolina, Florida and the Bahama Islands published in London in 1731 and 1743. Carolina parakeets were probably poisonous—French-American naturalist and painter John J. Audubon noted that cats apparently died from eating them, and they are known to have eaten the toxic seeds of cockleburs. | 2001-09-11T11:11:01Z | 2023-12-24T02:07:42Z | [
"Template:ISBN",
"Template:Speciesbox",
"Template:Cite web",
"Template:Commons",
"Template:Short description",
"Template:Ndash",
"Template:Reflist",
"Template:Cite iucn",
"Template:Citation needed",
"Template:R",
"Template:Clade",
"Template:Convert",
"Template:Cite book",
"Template:Cite news",
"Template:Cite journal",
"Template:Taxonbar",
"Template:Use dmy dates"
] | https://en.wikipedia.org/wiki/Carolina_parakeet |
6,324 | Collective trauma | The term collective trauma calls attention to the "psychological reactions to a traumatic event that affect[s] an entire society." Collective trauma does not only represent a historical fact or event, but is a collective memory of an awful event that happened to that group of people.
American sociologist Kai Erikson was one of the first to document collective trauma in his book Everything in Its Path, which documented the aftermath of a catastrophic flood in 1972.
Gilad Hirschberger of Interdisciplinary Center, Herzliya, Israel, defines the term:
The term collective trauma refers to the psychological reactions to a traumatic event that affect an entire society; it does not merely reflect an historical fact, the recollection of a terrible event that happened to a group of people. It suggests that the tragedy is represented in the collective memory of the group, and like all forms of memory it comprises not only a reproduction of the events, but also an ongoing reconstruction of the trauma in an attempt to make sense of it.
Clarifying the term collective, Ursula König (2018) focused on two different levels of collective trauma:
According to these two distinctions, a collective trauma can only be defined as such if affects can be clearly defined at either level. For example, the traumatisation of many individuals may not be considered collective, unless their traumatic experiences are used as key identity markers in public discourses and/or as a way of self-expression/-definition. Once trauma of many individuals is framed and used as a collective identity marker we can speak of it as such.
Furthermore, a distinction can be made between collective identity markers which in practice are all highly interwoven:
Traumatic events witnessed by an entire society can stir up collective sentiment, often resulting in a shift in that society's culture and mass actions.
Well known collective traumas include: the Holocaust, the Armenian genocide, slavery in the United States, the Nanjing Massacre, the atomic bombings of Hiroshima and Nagasaki, the Trail of Tears, the Great Irish Famine, attack on Pearl Harbor, the MS Estonia in Sweden, the September 11, 2001 attacks in the United States, the Halabja chemical attack, the Palestinian Nakba, the COVID-19 pandemic, and various others.
Collective traumas have been shown to play a key role in group identity formation (see: Law of Common Fate). During World War II, a US submarine, the USS Puffer (SS-268), came under several hours of depth charge attack by a Japanese surface vessel until the ship became convinced the submarine had somehow escaped. Psychological studies later showed that crewmen transferred to the submarine after the event were never accepted as part of the team. Later, US naval policy was changed so that after events of such psychological trauma, the crew would be dispersed to new assignments.
Rehabilitation of survivors becomes extremely difficult when an entire nation has experienced such severe traumas as war, genocide, torture, massacre, etc. Treatment of individuals is less effective when society itself is traumatized. Trauma remains chronic and can potentially reproduce itself as long as social causes are not addressed and perpetrators continue to enjoy impunity. Society as a whole may suffer from a form of chronic trauma. However, ways to heal collective trauma have recently been created (see section on Healing Collective Trauma below).
During the Algerian War, Frantz Omar Fanon found his practice of treatment of native Algerians ineffective due to the continuation of the horror of a colonial war. He emphasized about the social origin of traumas, joined the liberation movement and urged oppressed people to purge themselves of their degrading traumas through their collective liberation struggle. He made the following remarks in his letter of resignation, as the Head of the Psychiatry Department at the Blida-Joinville Hospital in Algeria:
"If psychiatry is the medical technique that aims to enable man no longer to be a stranger to his environment, I owe it to myself to affirm that the Arab, permanently an alien in his own country, lives in a state of absolute depersonalization".
Inculcation of horror and anxiety, through widespread torture, massacre, genocide and similar coercive measures has happened frequently in human history. There are plenty of examples in our modern history. Tyrants have always used their technique of "psychological artillery" in an attempt to cause havoc and confusion in the minds of people and hypnotize them with intimidation and cynicism. The result is a collective trauma that will pass through generations. There is no magic formula of rehabilitation. Collective trauma can be alleviated through cohesive and collective efforts such as recognition, remembrance, solidarity, communal therapy and massive cooperation.
Multiple international scientific studies have shown how the emotional states of a mother has a direct impact on the developing nervous system of their child and the ensuing development of their brain systems over time.
A study conducted in the aftermath of the Six day war in Israel in 1967 for example, found that women who were pregnant during the wars occurrence were statistically more likely to have had children with schizophrenia. What happened at the collective level of the country, was directly reflected in the individual neurobiological systems of the infants in the womb. Due to the direct correlation/connection between the nervous system and every other organ in our bodies, collective trauma is also evident at the cellular level. Trauma can thus not be understood in purely individual terms.
Collective trauma does not merely reflect a historical fact or the recollection of a traumatic event that happened to a group of people. Collective trauma suggests that the tragedy is represented in the collective memory of the group, and like all forms of memory it comprises not only a reproduction of the events, but also an ongoing reconstruction of the trauma in an attempt to make sense of it. Collective memory of a trauma is different from individual memory because collective memory persists beyond the lives of the direct survivors of the events, and is remembered by group members that may be far removed from the traumatic events in time and space.
Reliving traumatic experiences as a collective can lead to a vast range on mental health problems, including Post Traumatic Stress Disorder (PTSD), depression, and disassociation. With collective traumas including events like natural disasters and even historical traumas like The Holocaust, the psychological impact of these vary based on direct and indirect experience. These traumas can result in psychological conditions to prevail, for example we see how PTSD and Alexithymia was developed by survivors of the earthquakes in L'Aquila, Italy. PTSD symptoms can include re-experiencing your traumatic event, avoidance, and emotional numbing such as alexithymia, and many more emotional and physical symptoms . These symptoms and the condition of PTSD are not limited to the victims themselves, but generations after traumatic events as well, usually up to two generations, which can be attributed to a combination of epigenetics and collective cultural trauma (see these sections below). The mental health conditions due to collective trauma are not limited to PTSD, with studies showing higher levels of low self esteem in the children of holocaust survivors and higher levels of anxiety and depression in those who have experienced a collective historical trauma, like the Native Americans. Therefore, experiencing a collective trauma directly or indirectly can result in many mental health conditions for the collective.
When collective trauma is experienced, there are neurological and neurophysiological impacts on the victims and those affected. With most collective trauma accompanied by PTSD, there are two responses that victims are most likely to adopt: reexperiencing and/or hyperarousal and dissociation. These play a part in dictating what neural pathways the brain will form. PTSD and collective trauma have an impact on limbic function, and impact parts of the brain, like the right amygdala, hippocampus, parahippocampal, and temporopolar areas, where survivors of collective trauma experience a lower intensity, which has impact on mood in a negative way. As studies from the L'Aquila earthquake survivors show, the lower intensity of limbic regions in the survivors represents a defensive approach when tasked with emotional involvement, suggesting coping strategies in the form of distancing and disassociation, and a dysfunctional emotional regulating system.
Epigenetics is the influence your environment and behaviours have on how your genes work, and with more studies exploring how the epigenome is changed: collective trauma can also be considered. The epigenome is shaped by both genetic variation and environmental experiences, and we see how survivors of collective trauma can alter their epigenome. Exposure to trauma and stressors can alter gene regulation and expression leading to altered patterns of biology and health. Studies show that both mental and physical health outcomes suffer due to epigenetic reasons because of collective trauma. Studies show that through intrauterine signalling, the experience of negative maternal mood or stress during pregnancy can manifest in alterations in epigenetic patterns of offspring, with potential long-term effects on health outcomes, which can continue for generations to come Further links of parental care and breastfeeding composition also indicate to changes in genetic makeup in offspring, for example if the mother experiences higher levels of the stress hormone cortisol, this will be experienced also by the offspring either in utero or through breastfeeding.
Cultural trauma is a form of collective trauma that is seen on a societal and macro-level. With collective trauma being experienced communally- psychological, and mental health consequences of cultural trauma can be explored from individual and community-level perspectives, factoring in family dynamics and geopolitical factors that can amplify the trauma experienced. The Holocaust provides an example of how survivors and their children experienced impaired functioning and poor adjustment to their environments. Studies around refugees and immigrants also indicate how cultural trauma as a collective has vast negative mental health affects and how that is transmitted throughout communities and then generations through epigenetic transmission, but also through parental care that is dictated by family dynamics set by communities. An example of this can be witnessed through Sri Lanka, where a war and tsunami caused collective trauma to be experienced. On multiple levels, Sri Lankans who were affected by the war and tsunami saw changed in the dynamics of family relations, a lack of trust between community members and child rearing changed as well. These changed the cultural norms in Sri Lankan society, and created a negative environment where communities tended to be more dependent, passive, silent, without leadership, mistrustful, and suspicious. As a collectivist culture, this shared trauma changed the dynamic of communities in a significant way, and changed the cultural identities of many Sri Lankans. This highlights how collective trauma has an impact on cultural identity on a large scale
Technology provides many opportunities and potential for creative connection and collaboration, such as for example through commons based peer production, see for example commons-based peer production - Wikipedia itself is an example for this.
In the Stanford Social Innovation Review, authors Ijeoma Njaka & Duncan Peacock examine trauma in the context of social change, arguing that trauma inhibits and limits our sustained attention to the complex crises we currently face. They write:
Writer and founder of the Academy of Inner Science Thomas Hübl suggests that one of the most important connections for healing collective and intergenerational trauma is between science and spirit, which he argues brings together the "double helix of ancient wisdom and contemporary understanding." Humans experience well-being when we have agency, dignity, and health, and are connected to ourselves, each other, and our world in sustainable and life-giving ways. Trauma is the disconnection from these things. Those working on social change, therefore, need to identify the connections and disconnections in the issues they care about. They also need support when they experience disconnection in their own lives. | [
{
"paragraph_id": 0,
"text": "The term collective trauma calls attention to the \"psychological reactions to a traumatic event that affect[s] an entire society.\" Collective trauma does not only represent a historical fact or event, but is a collective memory of an awful event that happened to that group of people.",
"title": ""
},
{
"paragraph_id": 1,
"text": "American sociologist Kai Erikson was one of the first to document collective trauma in his book Everything in Its Path, which documented the aftermath of a catastrophic flood in 1972.",
"title": "Definition"
},
{
"paragraph_id": 2,
"text": "Gilad Hirschberger of Interdisciplinary Center, Herzliya, Israel, defines the term:",
"title": "Definition"
},
{
"paragraph_id": 3,
"text": "The term collective trauma refers to the psychological reactions to a traumatic event that affect an entire society; it does not merely reflect an historical fact, the recollection of a terrible event that happened to a group of people. It suggests that the tragedy is represented in the collective memory of the group, and like all forms of memory it comprises not only a reproduction of the events, but also an ongoing reconstruction of the trauma in an attempt to make sense of it.",
"title": "Definition"
},
{
"paragraph_id": 4,
"text": "Clarifying the term collective, Ursula König (2018) focused on two different levels of collective trauma:",
"title": "Definition"
},
{
"paragraph_id": 5,
"text": "According to these two distinctions, a collective trauma can only be defined as such if affects can be clearly defined at either level. For example, the traumatisation of many individuals may not be considered collective, unless their traumatic experiences are used as key identity markers in public discourses and/or as a way of self-expression/-definition. Once trauma of many individuals is framed and used as a collective identity marker we can speak of it as such.",
"title": "Definition"
},
{
"paragraph_id": 6,
"text": "Furthermore, a distinction can be made between collective identity markers which in practice are all highly interwoven:",
"title": "Definition"
},
{
"paragraph_id": 7,
"text": "Traumatic events witnessed by an entire society can stir up collective sentiment, often resulting in a shift in that society's culture and mass actions.",
"title": "Global impacts"
},
{
"paragraph_id": 8,
"text": "Well known collective traumas include: the Holocaust, the Armenian genocide, slavery in the United States, the Nanjing Massacre, the atomic bombings of Hiroshima and Nagasaki, the Trail of Tears, the Great Irish Famine, attack on Pearl Harbor, the MS Estonia in Sweden, the September 11, 2001 attacks in the United States, the Halabja chemical attack, the Palestinian Nakba, the COVID-19 pandemic, and various others.",
"title": "Global impacts"
},
{
"paragraph_id": 9,
"text": "Collective traumas have been shown to play a key role in group identity formation (see: Law of Common Fate). During World War II, a US submarine, the USS Puffer (SS-268), came under several hours of depth charge attack by a Japanese surface vessel until the ship became convinced the submarine had somehow escaped. Psychological studies later showed that crewmen transferred to the submarine after the event were never accepted as part of the team. Later, US naval policy was changed so that after events of such psychological trauma, the crew would be dispersed to new assignments.",
"title": "Global impacts"
},
{
"paragraph_id": 10,
"text": "Rehabilitation of survivors becomes extremely difficult when an entire nation has experienced such severe traumas as war, genocide, torture, massacre, etc. Treatment of individuals is less effective when society itself is traumatized. Trauma remains chronic and can potentially reproduce itself as long as social causes are not addressed and perpetrators continue to enjoy impunity. Society as a whole may suffer from a form of chronic trauma. However, ways to heal collective trauma have recently been created (see section on Healing Collective Trauma below).",
"title": "Global impacts"
},
{
"paragraph_id": 11,
"text": "During the Algerian War, Frantz Omar Fanon found his practice of treatment of native Algerians ineffective due to the continuation of the horror of a colonial war. He emphasized about the social origin of traumas, joined the liberation movement and urged oppressed people to purge themselves of their degrading traumas through their collective liberation struggle. He made the following remarks in his letter of resignation, as the Head of the Psychiatry Department at the Blida-Joinville Hospital in Algeria:",
"title": "Global impacts"
},
{
"paragraph_id": 12,
"text": "\"If psychiatry is the medical technique that aims to enable man no longer to be a stranger to his environment, I owe it to myself to affirm that the Arab, permanently an alien in his own country, lives in a state of absolute depersonalization\".",
"title": "Global impacts"
},
{
"paragraph_id": 13,
"text": "Inculcation of horror and anxiety, through widespread torture, massacre, genocide and similar coercive measures has happened frequently in human history. There are plenty of examples in our modern history. Tyrants have always used their technique of \"psychological artillery\" in an attempt to cause havoc and confusion in the minds of people and hypnotize them with intimidation and cynicism. The result is a collective trauma that will pass through generations. There is no magic formula of rehabilitation. Collective trauma can be alleviated through cohesive and collective efforts such as recognition, remembrance, solidarity, communal therapy and massive cooperation.",
"title": "Global impacts"
},
{
"paragraph_id": 14,
"text": "Multiple international scientific studies have shown how the emotional states of a mother has a direct impact on the developing nervous system of their child and the ensuing development of their brain systems over time.",
"title": "Global impacts"
},
{
"paragraph_id": 15,
"text": "A study conducted in the aftermath of the Six day war in Israel in 1967 for example, found that women who were pregnant during the wars occurrence were statistically more likely to have had children with schizophrenia. What happened at the collective level of the country, was directly reflected in the individual neurobiological systems of the infants in the womb. Due to the direct correlation/connection between the nervous system and every other organ in our bodies, collective trauma is also evident at the cellular level. Trauma can thus not be understood in purely individual terms.",
"title": "Global impacts"
},
{
"paragraph_id": 16,
"text": "Collective trauma does not merely reflect a historical fact or the recollection of a traumatic event that happened to a group of people. Collective trauma suggests that the tragedy is represented in the collective memory of the group, and like all forms of memory it comprises not only a reproduction of the events, but also an ongoing reconstruction of the trauma in an attempt to make sense of it. Collective memory of a trauma is different from individual memory because collective memory persists beyond the lives of the direct survivors of the events, and is remembered by group members that may be far removed from the traumatic events in time and space.",
"title": "Global impacts"
},
{
"paragraph_id": 17,
"text": "Reliving traumatic experiences as a collective can lead to a vast range on mental health problems, including Post Traumatic Stress Disorder (PTSD), depression, and disassociation. With collective traumas including events like natural disasters and even historical traumas like The Holocaust, the psychological impact of these vary based on direct and indirect experience. These traumas can result in psychological conditions to prevail, for example we see how PTSD and Alexithymia was developed by survivors of the earthquakes in L'Aquila, Italy. PTSD symptoms can include re-experiencing your traumatic event, avoidance, and emotional numbing such as alexithymia, and many more emotional and physical symptoms . These symptoms and the condition of PTSD are not limited to the victims themselves, but generations after traumatic events as well, usually up to two generations, which can be attributed to a combination of epigenetics and collective cultural trauma (see these sections below). The mental health conditions due to collective trauma are not limited to PTSD, with studies showing higher levels of low self esteem in the children of holocaust survivors and higher levels of anxiety and depression in those who have experienced a collective historical trauma, like the Native Americans. Therefore, experiencing a collective trauma directly or indirectly can result in many mental health conditions for the collective.",
"title": "Links to mental health"
},
{
"paragraph_id": 18,
"text": "When collective trauma is experienced, there are neurological and neurophysiological impacts on the victims and those affected. With most collective trauma accompanied by PTSD, there are two responses that victims are most likely to adopt: reexperiencing and/or hyperarousal and dissociation. These play a part in dictating what neural pathways the brain will form. PTSD and collective trauma have an impact on limbic function, and impact parts of the brain, like the right amygdala, hippocampus, parahippocampal, and temporopolar areas, where survivors of collective trauma experience a lower intensity, which has impact on mood in a negative way. As studies from the L'Aquila earthquake survivors show, the lower intensity of limbic regions in the survivors represents a defensive approach when tasked with emotional involvement, suggesting coping strategies in the form of distancing and disassociation, and a dysfunctional emotional regulating system.",
"title": "Neurological effects"
},
{
"paragraph_id": 19,
"text": "Epigenetics is the influence your environment and behaviours have on how your genes work, and with more studies exploring how the epigenome is changed: collective trauma can also be considered. The epigenome is shaped by both genetic variation and environmental experiences, and we see how survivors of collective trauma can alter their epigenome. Exposure to trauma and stressors can alter gene regulation and expression leading to altered patterns of biology and health. Studies show that both mental and physical health outcomes suffer due to epigenetic reasons because of collective trauma. Studies show that through intrauterine signalling, the experience of negative maternal mood or stress during pregnancy can manifest in alterations in epigenetic patterns of offspring, with potential long-term effects on health outcomes, which can continue for generations to come Further links of parental care and breastfeeding composition also indicate to changes in genetic makeup in offspring, for example if the mother experiences higher levels of the stress hormone cortisol, this will be experienced also by the offspring either in utero or through breastfeeding.",
"title": "Epigenetics"
},
{
"paragraph_id": 20,
"text": "Cultural trauma is a form of collective trauma that is seen on a societal and macro-level. With collective trauma being experienced communally- psychological, and mental health consequences of cultural trauma can be explored from individual and community-level perspectives, factoring in family dynamics and geopolitical factors that can amplify the trauma experienced. The Holocaust provides an example of how survivors and their children experienced impaired functioning and poor adjustment to their environments. Studies around refugees and immigrants also indicate how cultural trauma as a collective has vast negative mental health affects and how that is transmitted throughout communities and then generations through epigenetic transmission, but also through parental care that is dictated by family dynamics set by communities. An example of this can be witnessed through Sri Lanka, where a war and tsunami caused collective trauma to be experienced. On multiple levels, Sri Lankans who were affected by the war and tsunami saw changed in the dynamics of family relations, a lack of trust between community members and child rearing changed as well. These changed the cultural norms in Sri Lankan society, and created a negative environment where communities tended to be more dependent, passive, silent, without leadership, mistrustful, and suspicious. As a collectivist culture, this shared trauma changed the dynamic of communities in a significant way, and changed the cultural identities of many Sri Lankans. This highlights how collective trauma has an impact on cultural identity on a large scale",
"title": "Collective cultural trauma"
},
{
"paragraph_id": 21,
"text": "Technology provides many opportunities and potential for creative connection and collaboration, such as for example through commons based peer production, see for example commons-based peer production - Wikipedia itself is an example for this.",
"title": "Influence of technology on collective trauma"
},
{
"paragraph_id": 22,
"text": "In the Stanford Social Innovation Review, authors Ijeoma Njaka & Duncan Peacock examine trauma in the context of social change, arguing that trauma inhibits and limits our sustained attention to the complex crises we currently face. They write:",
"title": "Healing collective trauma"
},
{
"paragraph_id": 23,
"text": "Writer and founder of the Academy of Inner Science Thomas Hübl suggests that one of the most important connections for healing collective and intergenerational trauma is between science and spirit, which he argues brings together the \"double helix of ancient wisdom and contemporary understanding.\" Humans experience well-being when we have agency, dignity, and health, and are connected to ourselves, each other, and our world in sustainable and life-giving ways. Trauma is the disconnection from these things. Those working on social change, therefore, need to identify the connections and disconnections in the issues they care about. They also need support when they experience disconnection in their own lives.",
"title": "Healing collective trauma"
}
] | The term collective trauma calls attention to the "psychological reactions to a traumatic event that affect[s] an entire society." Collective trauma does not only represent a historical fact or event, but is a collective memory of an awful event that happened to that group of people. | 2001-09-21T13:20:15Z | 2023-12-18T17:27:02Z | [
"Template:Relevance inline",
"Template:Short description",
"Template:More citations needed",
"Template:Blockquote",
"Template:Reflist",
"Template:Cite journal",
"Template:Cite book"
] | https://en.wikipedia.org/wiki/Collective_trauma |
6,325 | Church (building) | A church, church building, or church house is a building used for Christian worship services and other Christian religious activities. The earliest identified Christian church is a house church founded between 233 and 256.
Sometimes, the word church is used by analogy and simplicity for the buildings of other religions, such as mosques and synagogues. Church is also used to describe a body or an assembly of Christian believers, while "the Church" may be used to refer to the worldwide Christian religious community as a whole.
In traditional Christian architecture, the plan view of a church often forms a Christian cross with the center aisle and seating representing the vertical beam and the bema and altar forming the horizontal. Towers or domes may inspire contemplation of the heavens. Modern churches have a variety of architectural styles and layouts. Some buildings designed for other purposes have been converted to churches, while many original church buildings have been put to other uses. From the 11th through the 14th centuries, there was a wave of church construction in Western Europe.
The word church is derived from Old English cirice, "place of assemblage set aside for Christian worship", from the Proto-Germanic kirika. This was probably borrowed via the Gothic from the Greek kyriake (oikia), kyriakon doma, "the Lord's (house)", from kyrios, "ruler, lord". Kyrios in turn comes from the Proto-Indo-European language root *keue meaning "to swell".
The Greek kyriakon, "of the Lord", was used of houses of Christian worship since c. 300 AD, especially in the East, although it was less common in this sense than ekklesia or basilike.
The earliest archeologically identified Christian church is a house church (domus ecclesiae), the Dura-Europos church, founded between 233 and 256.
In the second half of the 3rd century AD, the first purpose-built halls for Christian worship (aula ecclesiae) began to be constructed. Although many of these were destroyed early in the next century during the Diocletianic Persecution. Even larger and more elaborate churches began to appear during the reign of Emperor Constantine the Great.
From the 11th through the 14th centuries, a wave of cathedral building and the construction of smaller parish churches occurred across Western Europe. Besides serving as a place of worship, the cathedral or parish church was frequently employed as a general gathering place by the communities in which they were located, hosting such events as guild meetings, banquets, mystery plays, and fairs. Church grounds and buildings were also used for the threshing and storage of grain.
Between 1000 and 1200, the Romanesque style became popular across Europe. The Romanesque style is defined by large and bulky edifices typically composed of simple, compact, sparsely decorated geometric structures. Frequent features of the Romanesque church include circular arches, round or octagonal towers, and cushion capitals on pillars. In the early Romanesque era, coffering on the ceiling was fashionable, while later in the same era, groined vaults gained popularity. Interiors widened, and the motifs of sculptures took on more epic traits and themes.
The Gothic style emerged around 1140 in Île-de-France and subsequently spread throughout Europe. Gothic churches lost the compact qualities of the Romanesque era, and decorations often contained symbolic and allegorical features. The first pointed arches, rib vaults, and buttresses began to appear, all possessing geometric properties that reduced the need for large, rigid walls to ensure structural stability. This also permitted the size of windows to increase, producing brighter and lighter interiors. Nave ceilings rose, and pillars and steeples heightened. Many architects used these developments to push the limits of structural possibility, an inclination that resulted in the collapse of several towers whose designs that had unwittingly exceeded the boundaries of soundness. In Germany, the Netherlands, and Spain, it became popular to build hall churches, a style in which every vault would be built to the same height.
Gothic cathedrals were lavishly designed, as in the Romanesque era, and many share Romanesque traits. However, several also exhibit unprecedented degrees of detail and complexity in decoration. The Notre-Dame de Paris and Notre-Dame de Reims in France, as well as the San Francesco d’Assisi in Palermo, the Salisbury Cathedral and Wool Church in England, and Santhome Church in Chennai, India, show the elaborate stylings characteristic of Gothic cathedrals.
Some of the most well-known gothic churches remained unfinished for centuries after the style fell out of popularity. One such example is the construction of the Cologne Cathedral, which began in 1248, was halted in 1473, and was not resumed until 1842.
In the 15th and 16th centuries, the changes in ethics and society due to the Renaissance and the Reformation also influenced the building of churches. The common style was much like the Gothic style but simplified. The basilica was not the most popular type of church anymore, but instead, hall churches were built. Typical features are columns and classical capitals.
In Protestant churches, where the proclamation of God's Word is of particular importance, the visitor's line of sight is directed towards the pulpit.
The Baroque style was first used in Italy around 1575. From there, it spread to the rest of Europe and the European colonies. The building industry increased heavily during the Baroque era. Buildings, even churches, were used to indicate wealth, authority, and influence. The use of forms known from the Renaissance was extremely exaggerated. Domes and capitals were decorated with moulding, and the former stucco sculptures were replaced by fresco paintings on the ceilings. For the first time, churches were seen as one connected work of art, and consistent artistic concepts were developed. Instead of long buildings, more central-plan buildings were created. The sprawling decoration with floral ornamentation and mythological motives lasted until about 1720 in the Rococo era.
The Protestant parishes preferred lateral churches, in which all the visitors could be as close as possible to the pulpit and the altar.
A common trait of the architecture of many churches is the shape of a cross (a long central rectangle, with side rectangles and a rectangle in front for the altar space or sanctuary). These churches also often have a dome or other large vaulted space in the interior to represent or draw attention to the heavens. Other common shapes for churches include a circle, to represent eternity, or an octagon or similar star shape, to represent the church's bringing light to the world. Another common feature is the spire, a tall tower at the "west" end of the church or over the crossing.
Another common feature of many Christian churches is the eastwards orientation of the front altar. Often, the altar will not be oriented due east but toward the sunrise. This tradition originated in Byzantium in the 4th century and became prevalent in the West in the 8th and 9th centuries. The old Roman custom of having the altar at the west end and the entrance at the east was sometimes followed as late as the 11th century, even in areas of northern Europe under Frankish rule, as seen in Petershausen (Constance), Bamberg Cathedral, Augsburg Cathedral, Regensburg Cathedral, and Hildesheim Cathedral.
The Latin word basilica was initially used to describe a Roman public building usually located in the forum of a Roman town. After the Roman Empire became officially Christian, the term came by extension to refer to a large and influential church that has been given special ceremonial rights by the Pope. The word thus retains two senses today, one architectural and the other ecclesiastical.
A cathedral is a church, usually Catholic, Anglican, Oriental Orthodox or Eastern Orthodox, housing the seat of a bishop. The word cathedral takes its name from cathedra, or Bishop's Throne (In Latin: ecclesia cathedralis). The term is sometimes (improperly) used to refer to any church of great size.
A church with a cathedral function is not necessarily a large building. It might be as small as Christ Church Cathedral in Oxford, England, Porvoo Cathedral in Porvoo, Finland, Sacred Heart Cathedral in Raleigh, United States, or Chur Cathedral in Switzerland. However, frequently, the cathedral, along with some of the abbey churches, was the largest building in any region.
A pilgrimage church is a church to which pilgrimages are regularly made, or a church along a pilgrimage route, often located at the tomb of a saints, or holding icons or relics to which miraculous properties are ascribed, the site of Marian apparitions, etc.
A conventual church (or monastery church, minster, katholikon) is the main church in a Christian monastery or abbey.
During the Middle Ages, a proprietary church was a church, abbey, or cloister built on the private grounds of a feudal lord, over which he retained proprietary interests.
A collegiate church is a church where the daily office of worship is maintained by a college of canons, which may be presided over by a dean or provost. Collegiate churches were often supported by extensive lands held by the church, or by tithe income from appropriated benefices. They commonly provide distinct spaces for congregational worship and for the choir offices of their clerical community.
The architecture of evangelical places of worship is mainly characterized by its sobriety. The Latin cross is a well known Christian symbol that can usually be seen on the building of an evangelical church and that identifies the place's belonging. Some services take place in theaters, schools or multipurpose rooms, rented for Sunday only. There is usually a baptistery at the front of the church (in what is known as the chancel in historic traditions) or in a separate room for baptisms by immersion.
Worship services take on impressive proportions in the megachurches (churches where more than 2,000 people gather every Sunday). In some of these megachurches, more than 10,000 people gather every Sunday. The term gigachurch is sometimes used. For example, Lakewood Church (United States) or Yoido Full Gospel Church (South Korea).
In some countries of the world which apply sharia or communism, government authorizations for worship are complex for Christians. Because of persecution of Christians, Evangelical house churches have thus developed. For example, there is the Evangelical house churches in China movement. The meetings thus take place in private houses, in secret and in "illegality".
Old and disused church buildings can be seen as an interesting proposition for developers as the architecture and location often provide for attractive homes or city centre entertainment venues. On the other hand, many newer churches have decided to host meetings in public buildings such as schools, universities, cinemas or theatres.
There is another trend to convert old buildings for worship rather than face the construction costs and planning difficulties of a new build. Unusual venues in the UK include a former tram power station, a former bus garage, a former cinema and bingo hall, a former Territorial Army drill hall, and a former synagogue. HMS Tees served as a floating church for mariners at Liverpool from 1827 until she sank in 1872. A windmill has also been converted into a church at Reigate Heath.
There have been increased partnerships between church management and private real estate companies to redevelop church properties into mixed uses. While it has garnered criticism, the partnership allows congregations to increase revenue while preserving the property. | [
{
"paragraph_id": 0,
"text": "A church, church building, or church house is a building used for Christian worship services and other Christian religious activities. The earliest identified Christian church is a house church founded between 233 and 256.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Sometimes, the word church is used by analogy and simplicity for the buildings of other religions, such as mosques and synagogues. Church is also used to describe a body or an assembly of Christian believers, while \"the Church\" may be used to refer to the worldwide Christian religious community as a whole.",
"title": ""
},
{
"paragraph_id": 2,
"text": "In traditional Christian architecture, the plan view of a church often forms a Christian cross with the center aisle and seating representing the vertical beam and the bema and altar forming the horizontal. Towers or domes may inspire contemplation of the heavens. Modern churches have a variety of architectural styles and layouts. Some buildings designed for other purposes have been converted to churches, while many original church buildings have been put to other uses. From the 11th through the 14th centuries, there was a wave of church construction in Western Europe.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The word church is derived from Old English cirice, \"place of assemblage set aside for Christian worship\", from the Proto-Germanic kirika. This was probably borrowed via the Gothic from the Greek kyriake (oikia), kyriakon doma, \"the Lord's (house)\", from kyrios, \"ruler, lord\". Kyrios in turn comes from the Proto-Indo-European language root *keue meaning \"to swell\".",
"title": "Etymology"
},
{
"paragraph_id": 4,
"text": "The Greek kyriakon, \"of the Lord\", was used of houses of Christian worship since c. 300 AD, especially in the East, although it was less common in this sense than ekklesia or basilike.",
"title": "Etymology"
},
{
"paragraph_id": 5,
"text": "The earliest archeologically identified Christian church is a house church (domus ecclesiae), the Dura-Europos church, founded between 233 and 256.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "In the second half of the 3rd century AD, the first purpose-built halls for Christian worship (aula ecclesiae) began to be constructed. Although many of these were destroyed early in the next century during the Diocletianic Persecution. Even larger and more elaborate churches began to appear during the reign of Emperor Constantine the Great.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "From the 11th through the 14th centuries, a wave of cathedral building and the construction of smaller parish churches occurred across Western Europe. Besides serving as a place of worship, the cathedral or parish church was frequently employed as a general gathering place by the communities in which they were located, hosting such events as guild meetings, banquets, mystery plays, and fairs. Church grounds and buildings were also used for the threshing and storage of grain.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "Between 1000 and 1200, the Romanesque style became popular across Europe. The Romanesque style is defined by large and bulky edifices typically composed of simple, compact, sparsely decorated geometric structures. Frequent features of the Romanesque church include circular arches, round or octagonal towers, and cushion capitals on pillars. In the early Romanesque era, coffering on the ceiling was fashionable, while later in the same era, groined vaults gained popularity. Interiors widened, and the motifs of sculptures took on more epic traits and themes.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "The Gothic style emerged around 1140 in Île-de-France and subsequently spread throughout Europe. Gothic churches lost the compact qualities of the Romanesque era, and decorations often contained symbolic and allegorical features. The first pointed arches, rib vaults, and buttresses began to appear, all possessing geometric properties that reduced the need for large, rigid walls to ensure structural stability. This also permitted the size of windows to increase, producing brighter and lighter interiors. Nave ceilings rose, and pillars and steeples heightened. Many architects used these developments to push the limits of structural possibility, an inclination that resulted in the collapse of several towers whose designs that had unwittingly exceeded the boundaries of soundness. In Germany, the Netherlands, and Spain, it became popular to build hall churches, a style in which every vault would be built to the same height.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "Gothic cathedrals were lavishly designed, as in the Romanesque era, and many share Romanesque traits. However, several also exhibit unprecedented degrees of detail and complexity in decoration. The Notre-Dame de Paris and Notre-Dame de Reims in France, as well as the San Francesco d’Assisi in Palermo, the Salisbury Cathedral and Wool Church in England, and Santhome Church in Chennai, India, show the elaborate stylings characteristic of Gothic cathedrals.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "Some of the most well-known gothic churches remained unfinished for centuries after the style fell out of popularity. One such example is the construction of the Cologne Cathedral, which began in 1248, was halted in 1473, and was not resumed until 1842.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "In the 15th and 16th centuries, the changes in ethics and society due to the Renaissance and the Reformation also influenced the building of churches. The common style was much like the Gothic style but simplified. The basilica was not the most popular type of church anymore, but instead, hall churches were built. Typical features are columns and classical capitals.",
"title": "History"
},
{
"paragraph_id": 13,
"text": "In Protestant churches, where the proclamation of God's Word is of particular importance, the visitor's line of sight is directed towards the pulpit.",
"title": "History"
},
{
"paragraph_id": 14,
"text": "The Baroque style was first used in Italy around 1575. From there, it spread to the rest of Europe and the European colonies. The building industry increased heavily during the Baroque era. Buildings, even churches, were used to indicate wealth, authority, and influence. The use of forms known from the Renaissance was extremely exaggerated. Domes and capitals were decorated with moulding, and the former stucco sculptures were replaced by fresco paintings on the ceilings. For the first time, churches were seen as one connected work of art, and consistent artistic concepts were developed. Instead of long buildings, more central-plan buildings were created. The sprawling decoration with floral ornamentation and mythological motives lasted until about 1720 in the Rococo era.",
"title": "History"
},
{
"paragraph_id": 15,
"text": "The Protestant parishes preferred lateral churches, in which all the visitors could be as close as possible to the pulpit and the altar.",
"title": "History"
},
{
"paragraph_id": 16,
"text": "A common trait of the architecture of many churches is the shape of a cross (a long central rectangle, with side rectangles and a rectangle in front for the altar space or sanctuary). These churches also often have a dome or other large vaulted space in the interior to represent or draw attention to the heavens. Other common shapes for churches include a circle, to represent eternity, or an octagon or similar star shape, to represent the church's bringing light to the world. Another common feature is the spire, a tall tower at the \"west\" end of the church or over the crossing.",
"title": "Architecture"
},
{
"paragraph_id": 17,
"text": "Another common feature of many Christian churches is the eastwards orientation of the front altar. Often, the altar will not be oriented due east but toward the sunrise. This tradition originated in Byzantium in the 4th century and became prevalent in the West in the 8th and 9th centuries. The old Roman custom of having the altar at the west end and the entrance at the east was sometimes followed as late as the 11th century, even in areas of northern Europe under Frankish rule, as seen in Petershausen (Constance), Bamberg Cathedral, Augsburg Cathedral, Regensburg Cathedral, and Hildesheim Cathedral.",
"title": "Architecture"
},
{
"paragraph_id": 18,
"text": "The Latin word basilica was initially used to describe a Roman public building usually located in the forum of a Roman town. After the Roman Empire became officially Christian, the term came by extension to refer to a large and influential church that has been given special ceremonial rights by the Pope. The word thus retains two senses today, one architectural and the other ecclesiastical.",
"title": "Types"
},
{
"paragraph_id": 19,
"text": "A cathedral is a church, usually Catholic, Anglican, Oriental Orthodox or Eastern Orthodox, housing the seat of a bishop. The word cathedral takes its name from cathedra, or Bishop's Throne (In Latin: ecclesia cathedralis). The term is sometimes (improperly) used to refer to any church of great size.",
"title": "Types"
},
{
"paragraph_id": 20,
"text": "A church with a cathedral function is not necessarily a large building. It might be as small as Christ Church Cathedral in Oxford, England, Porvoo Cathedral in Porvoo, Finland, Sacred Heart Cathedral in Raleigh, United States, or Chur Cathedral in Switzerland. However, frequently, the cathedral, along with some of the abbey churches, was the largest building in any region.",
"title": "Types"
},
{
"paragraph_id": 21,
"text": "A pilgrimage church is a church to which pilgrimages are regularly made, or a church along a pilgrimage route, often located at the tomb of a saints, or holding icons or relics to which miraculous properties are ascribed, the site of Marian apparitions, etc.",
"title": "Types"
},
{
"paragraph_id": 22,
"text": "A conventual church (or monastery church, minster, katholikon) is the main church in a Christian monastery or abbey.",
"title": "Types"
},
{
"paragraph_id": 23,
"text": "During the Middle Ages, a proprietary church was a church, abbey, or cloister built on the private grounds of a feudal lord, over which he retained proprietary interests.",
"title": "Types"
},
{
"paragraph_id": 24,
"text": "A collegiate church is a church where the daily office of worship is maintained by a college of canons, which may be presided over by a dean or provost. Collegiate churches were often supported by extensive lands held by the church, or by tithe income from appropriated benefices. They commonly provide distinct spaces for congregational worship and for the choir offices of their clerical community.",
"title": "Types"
},
{
"paragraph_id": 25,
"text": "The architecture of evangelical places of worship is mainly characterized by its sobriety. The Latin cross is a well known Christian symbol that can usually be seen on the building of an evangelical church and that identifies the place's belonging. Some services take place in theaters, schools or multipurpose rooms, rented for Sunday only. There is usually a baptistery at the front of the church (in what is known as the chancel in historic traditions) or in a separate room for baptisms by immersion.",
"title": "Types"
},
{
"paragraph_id": 26,
"text": "Worship services take on impressive proportions in the megachurches (churches where more than 2,000 people gather every Sunday). In some of these megachurches, more than 10,000 people gather every Sunday. The term gigachurch is sometimes used. For example, Lakewood Church (United States) or Yoido Full Gospel Church (South Korea).",
"title": "Types"
},
{
"paragraph_id": 27,
"text": "In some countries of the world which apply sharia or communism, government authorizations for worship are complex for Christians. Because of persecution of Christians, Evangelical house churches have thus developed. For example, there is the Evangelical house churches in China movement. The meetings thus take place in private houses, in secret and in \"illegality\".",
"title": "Types"
},
{
"paragraph_id": 28,
"text": "Old and disused church buildings can be seen as an interesting proposition for developers as the architecture and location often provide for attractive homes or city centre entertainment venues. On the other hand, many newer churches have decided to host meetings in public buildings such as schools, universities, cinemas or theatres.",
"title": "Types"
},
{
"paragraph_id": 29,
"text": "There is another trend to convert old buildings for worship rather than face the construction costs and planning difficulties of a new build. Unusual venues in the UK include a former tram power station, a former bus garage, a former cinema and bingo hall, a former Territorial Army drill hall, and a former synagogue. HMS Tees served as a floating church for mariners at Liverpool from 1827 until she sank in 1872. A windmill has also been converted into a church at Reigate Heath.",
"title": "Types"
},
{
"paragraph_id": 30,
"text": "There have been increased partnerships between church management and private real estate companies to redevelop church properties into mixed uses. While it has garnered criticism, the partnership allows congregations to increase revenue while preserving the property.",
"title": "Types"
}
] | A church, church building, or church house is a building used for Christian worship services and other Christian religious activities. The earliest identified Christian church is a house church founded between 233 and 256. Sometimes, the word church is used by analogy and simplicity for the buildings of other religions, such as mosques and synagogues. Church is also used to describe a body or an assembly of Christian believers, while "the Church" may be used to refer to the worldwide Christian religious community as a whole. In traditional Christian architecture, the plan view of a church often forms a Christian cross with the center aisle and seating representing the vertical beam and the bema and altar forming the horizontal. Towers or domes may inspire contemplation of the heavens. Modern churches have a variety of architectural styles and layouts. Some buildings designed for other purposes have been converted to churches, while many original church buildings have been put to other uses. From the 11th through the 14th centuries, there was a wave of church construction in Western Europe. | 2001-10-17T23:05:47Z | 2023-12-19T12:17:22Z | [
"Template:Place of worship",
"Template:Use dmy dates",
"Template:C.",
"Template:Portal",
"Template:Cite news",
"Template:See",
"Template:Christianity footer",
"Template:Transliteration",
"Template:Cite book",
"Template:ISBN",
"Template:Cn",
"Template:Main",
"Template:Reflist",
"Template:Redirect",
"Template:PIE",
"Template:Clarify",
"Template:Commons",
"Template:Cite web",
"Template:Wikiquote",
"Template:Christianity",
"Template:Main article",
"Template:Lang-la",
"Template:Webarchive",
"Template:Short description",
"Template:Authority control",
"Template:Lang",
"Template:HMS",
"Template:Wiktionary",
"Template:CathEncy"
] | https://en.wikipedia.org/wiki/Church_(building) |
6,326 | Childe's Tomb | Childe's Tomb is a granite cross on Dartmoor, Devon, England. Although not in its original form, it is more elaborate than most of the crosses on Dartmoor, being raised upon a constructed base, and it is known that a kistvaen is underneath.
A well-known legend attached to the site, first recorded in 1630 by Tristram Risdon, concerns a wealthy hunter, Childe, who became lost in a snow storm and supposedly died there despite disembowelling his horse and climbing into its body for protection. The legend relates that Childe left a note of some sort saying that whoever found and buried his body would inherit his lands at Plymstock. After a race between the monks of Tavistock Abbey and the men of Plymstock, the Abbey won.
The tomb was virtually destroyed in 1812 by a man who stole most of the stones to build a house nearby, but it was partly reconstructed in 1890.
Childe's Tomb is a reconstructed granite cross on the south-east edge of Foxtor Mires, about 500 metres north of Fox Tor on Dartmoor, Devon, England at grid reference SX625704. According to William Burt, in his notes to Dartmoor, a Descriptive Poem by N. T. Carrington (1826), the original tomb consisted of a pedestal of three steps, the lowest of which was built of four stones each six feet long and twelve inches square. The two upper steps were made of eight shorter but similarly shaped stones, and on top was an octagonal block about three feet high with a cross fixed upon it.
The tomb lies on the line of several cairns that marked the east-west route of the ancient Monks' Path between Buckfast Abbey and Tavistock Abbey and it was no doubt erected here as part of that route: it would have been particularly useful in this part of the moor with few landmarks where a traveller straying from the path could easily end up in Foxtor Mires. Tristram Risdon, writing in about 1630, said that Childe's Tomb was one of three remarkable things in the Forest of Dartmoor (the others being Crockern Tor and Wistman's Wood). Risdon also stated that the original tomb bore an inscription: "They fyrste that fyndes and bringes mee to my grave, The priorie of Plimstoke they shall have", but no sign of this has ever been found.
Today the cross, which is a replacement, is about 3 feet 4 inches (1.02 m) tall and 1 foot 8 inches (0.51 m) across at the crosspiece, and it has its base in a socket stone which rests on a pedestal of granite blocks that raises the total height of the cross to 7 ft (2.1 m). The original, now broken, socket stone for the cross lies nearby. The whole is surrounded by a circle of granite stones set on their edge which once surrounded the cairn—the rocks of which are now scattered around—that was originally built over a large kistvaen that still exists beneath the pedestal.
In the early 19th century there was much interest in enclosing and "improving" the open moorland on Dartmoor, encouraged by Sir Thomas Tyrwhitt's early successes at Tor Royal near Princetown. Enclosure was aided by the greatly enhanced access provided by the construction of the first turnpike roads over the moor: the road between Ashburton and Two Bridges opened in around 1800, for instance. In February 1809 one Thomas Windeatt, from Bridgetown, Totnes, took over the lease of a plot of land (a "newtake") of about 582 acres in the valley of the River Swincombe. In 1812 Windeatt started to build a farmhouse, Fox Tor Farm, on his land and his workmen robbed the nearby Childe's Tomb of most of its stones for the building and its doorsteps.
In 1902 William Crossing wrote that he had been told by an old moorman that some of the granite blocks from the tomb's pedestal had also been used to make a clapper bridge across a stream flowing into the River Swincombe near the farm. The moorman also said that they had lettering on their undersides. This encouraged Crossing to arrange to lift the clapper bridge, but no inscription was found. However, he did locate nine out of the twelve stones that had made up the pedestal, as well as the broken socket stone for the cross.
Crossing rediscovered the original site of the tomb in 1882 and said that all that remained was a small mound and some half buried stones. He cleared out the kistvaen, reporting that it was 5 feet 6 inches (1.68 m) long by 2 feet 8 inches (81 cm) wide and that unlike most kistvaens found on the moor, the stones lining it had apparently been shaped by man, which led him to suggest that it was less old than most. Having located most of the stones of the original tomb, Crossing thought that it could be rebuilt in its original form with little effort, but it was not to be.
J. Brooking Rowe, writing in 1895, states that the tomb was re-erected in 1890 under the direction of Mr. E. Fearnley Tanner, who said that he was dissatisfied with the result because several stones were missing and it was difficult to recreate the original character of the monument. Tanner was the honourable secretary of the Dartmoor Preservation Association, and this reconstruction was one of the first acts of that organisation. The replacement base and cross were made in Holne in 1885.
According to legend, the cross was erected over the kistvaen ('chest-stone' i.e. burial chamber) of Childe the Hunter, who was Ordulf, son of Ordgar, an Anglo-Saxon Earl of Devon in the 11th century. The name Childe is probably derived from the Old English word cild which was used as a title of honour.
Legend has it that Childe was in a party hunting on the moor when they were caught in some changeable weather. Childe became separated from the main party and was lost. In order to save himself from dying of exposure, he killed his horse, disembowelled it and crept inside the warm carcass for shelter. He nevertheless froze to death, but before he died, he wrote a note to the effect that whoever should find him and bury him in their church should inherit his Plymstock estate.
His body was found by the monks of Tavistock Abbey, who started to carry it back. However, they heard of a plot to ambush them by the people of Plymstock, at a bridge over the River Tavy. They took a detour and built a new bridge over the river, just outside Tavistock. They were successful in burying the body in the grounds of the Abbey and inherited the Plymstock estate.
The first account of this story is to be found in Risdon's Survey of Devon which was completed in around 1632:
It is left us by tradition that one Childe of Plimstoke, a man of fair possessions, having no issue, ordained, by his will, that wheresoever he should happen to be buried, to that church his lands should belong. It so fortuned, that he riding to hunt in the forest of Dartmore, being in pursuit of his game, casually lost his company, and his way likewise. The season then being so cold, and he so benumed therewith, as he was enforced to kill his horse, and embowelled him, to creep into his belly to get heat; which not able to preserve him, was there frozen to death; and so found, was carried by Tavistoke men to be buried in the church of that abbey; which was so secretly done but the inhabitants of Plymstoke had knowledge thereof; which to prevent, they resorted to defend the carriage of the corpse over the bridge, where, they conceived, necessity compelled them to pass. But they were deceived by guile; for the Tavistoke men forthwith built a slight bridge, and passed over at another place without resistance, buried the body, and enjoyed the lands; in memory whereof the bridge beareth the name of Guilebridge to this day.
Finberg pointed out, however, that a document of 1651 refers to Tavistock's guildhall as Guilehall, so Guilebridge is more likely to be guild bridge, probably because it was built or maintained by one of the town guilds.
Devon folk singer Seth Lakeman sang about Childe the Hunter on his 2006 album Freedom Fields.
50°31′02″N 3°56′27″W / 50.51719°N 3.94085°W / 50.51719; -3.94085 | [
{
"paragraph_id": 0,
"text": "Childe's Tomb is a granite cross on Dartmoor, Devon, England. Although not in its original form, it is more elaborate than most of the crosses on Dartmoor, being raised upon a constructed base, and it is known that a kistvaen is underneath.",
"title": ""
},
{
"paragraph_id": 1,
"text": "A well-known legend attached to the site, first recorded in 1630 by Tristram Risdon, concerns a wealthy hunter, Childe, who became lost in a snow storm and supposedly died there despite disembowelling his horse and climbing into its body for protection. The legend relates that Childe left a note of some sort saying that whoever found and buried his body would inherit his lands at Plymstock. After a race between the monks of Tavistock Abbey and the men of Plymstock, the Abbey won.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The tomb was virtually destroyed in 1812 by a man who stole most of the stones to build a house nearby, but it was partly reconstructed in 1890.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Childe's Tomb is a reconstructed granite cross on the south-east edge of Foxtor Mires, about 500 metres north of Fox Tor on Dartmoor, Devon, England at grid reference SX625704. According to William Burt, in his notes to Dartmoor, a Descriptive Poem by N. T. Carrington (1826), the original tomb consisted of a pedestal of three steps, the lowest of which was built of four stones each six feet long and twelve inches square. The two upper steps were made of eight shorter but similarly shaped stones, and on top was an octagonal block about three feet high with a cross fixed upon it.",
"title": "Description"
},
{
"paragraph_id": 4,
"text": "The tomb lies on the line of several cairns that marked the east-west route of the ancient Monks' Path between Buckfast Abbey and Tavistock Abbey and it was no doubt erected here as part of that route: it would have been particularly useful in this part of the moor with few landmarks where a traveller straying from the path could easily end up in Foxtor Mires. Tristram Risdon, writing in about 1630, said that Childe's Tomb was one of three remarkable things in the Forest of Dartmoor (the others being Crockern Tor and Wistman's Wood). Risdon also stated that the original tomb bore an inscription: \"They fyrste that fyndes and bringes mee to my grave, The priorie of Plimstoke they shall have\", but no sign of this has ever been found.",
"title": "Description"
},
{
"paragraph_id": 5,
"text": "Today the cross, which is a replacement, is about 3 feet 4 inches (1.02 m) tall and 1 foot 8 inches (0.51 m) across at the crosspiece, and it has its base in a socket stone which rests on a pedestal of granite blocks that raises the total height of the cross to 7 ft (2.1 m). The original, now broken, socket stone for the cross lies nearby. The whole is surrounded by a circle of granite stones set on their edge which once surrounded the cairn—the rocks of which are now scattered around—that was originally built over a large kistvaen that still exists beneath the pedestal.",
"title": "Description"
},
{
"paragraph_id": 6,
"text": "In the early 19th century there was much interest in enclosing and \"improving\" the open moorland on Dartmoor, encouraged by Sir Thomas Tyrwhitt's early successes at Tor Royal near Princetown. Enclosure was aided by the greatly enhanced access provided by the construction of the first turnpike roads over the moor: the road between Ashburton and Two Bridges opened in around 1800, for instance. In February 1809 one Thomas Windeatt, from Bridgetown, Totnes, took over the lease of a plot of land (a \"newtake\") of about 582 acres in the valley of the River Swincombe. In 1812 Windeatt started to build a farmhouse, Fox Tor Farm, on his land and his workmen robbed the nearby Childe's Tomb of most of its stones for the building and its doorsteps.",
"title": "Destruction"
},
{
"paragraph_id": 7,
"text": "In 1902 William Crossing wrote that he had been told by an old moorman that some of the granite blocks from the tomb's pedestal had also been used to make a clapper bridge across a stream flowing into the River Swincombe near the farm. The moorman also said that they had lettering on their undersides. This encouraged Crossing to arrange to lift the clapper bridge, but no inscription was found. However, he did locate nine out of the twelve stones that had made up the pedestal, as well as the broken socket stone for the cross.",
"title": "Destruction"
},
{
"paragraph_id": 8,
"text": "Crossing rediscovered the original site of the tomb in 1882 and said that all that remained was a small mound and some half buried stones. He cleared out the kistvaen, reporting that it was 5 feet 6 inches (1.68 m) long by 2 feet 8 inches (81 cm) wide and that unlike most kistvaens found on the moor, the stones lining it had apparently been shaped by man, which led him to suggest that it was less old than most. Having located most of the stones of the original tomb, Crossing thought that it could be rebuilt in its original form with little effort, but it was not to be.",
"title": "Reconstruction"
},
{
"paragraph_id": 9,
"text": "J. Brooking Rowe, writing in 1895, states that the tomb was re-erected in 1890 under the direction of Mr. E. Fearnley Tanner, who said that he was dissatisfied with the result because several stones were missing and it was difficult to recreate the original character of the monument. Tanner was the honourable secretary of the Dartmoor Preservation Association, and this reconstruction was one of the first acts of that organisation. The replacement base and cross were made in Holne in 1885.",
"title": "Reconstruction"
},
{
"paragraph_id": 10,
"text": "According to legend, the cross was erected over the kistvaen ('chest-stone' i.e. burial chamber) of Childe the Hunter, who was Ordulf, son of Ordgar, an Anglo-Saxon Earl of Devon in the 11th century. The name Childe is probably derived from the Old English word cild which was used as a title of honour.",
"title": "Childe the Hunter"
},
{
"paragraph_id": 11,
"text": "Legend has it that Childe was in a party hunting on the moor when they were caught in some changeable weather. Childe became separated from the main party and was lost. In order to save himself from dying of exposure, he killed his horse, disembowelled it and crept inside the warm carcass for shelter. He nevertheless froze to death, but before he died, he wrote a note to the effect that whoever should find him and bury him in their church should inherit his Plymstock estate.",
"title": "Childe the Hunter"
},
{
"paragraph_id": 12,
"text": "His body was found by the monks of Tavistock Abbey, who started to carry it back. However, they heard of a plot to ambush them by the people of Plymstock, at a bridge over the River Tavy. They took a detour and built a new bridge over the river, just outside Tavistock. They were successful in burying the body in the grounds of the Abbey and inherited the Plymstock estate.",
"title": "Childe the Hunter"
},
{
"paragraph_id": 13,
"text": "The first account of this story is to be found in Risdon's Survey of Devon which was completed in around 1632:",
"title": "Childe the Hunter"
},
{
"paragraph_id": 14,
"text": "It is left us by tradition that one Childe of Plimstoke, a man of fair possessions, having no issue, ordained, by his will, that wheresoever he should happen to be buried, to that church his lands should belong. It so fortuned, that he riding to hunt in the forest of Dartmore, being in pursuit of his game, casually lost his company, and his way likewise. The season then being so cold, and he so benumed therewith, as he was enforced to kill his horse, and embowelled him, to creep into his belly to get heat; which not able to preserve him, was there frozen to death; and so found, was carried by Tavistoke men to be buried in the church of that abbey; which was so secretly done but the inhabitants of Plymstoke had knowledge thereof; which to prevent, they resorted to defend the carriage of the corpse over the bridge, where, they conceived, necessity compelled them to pass. But they were deceived by guile; for the Tavistoke men forthwith built a slight bridge, and passed over at another place without resistance, buried the body, and enjoyed the lands; in memory whereof the bridge beareth the name of Guilebridge to this day.",
"title": "Childe the Hunter"
},
{
"paragraph_id": 15,
"text": "Finberg pointed out, however, that a document of 1651 refers to Tavistock's guildhall as Guilehall, so Guilebridge is more likely to be guild bridge, probably because it was built or maintained by one of the town guilds.",
"title": "Childe the Hunter"
},
{
"paragraph_id": 16,
"text": "Devon folk singer Seth Lakeman sang about Childe the Hunter on his 2006 album Freedom Fields.",
"title": "Childe the Hunter"
},
{
"paragraph_id": 17,
"text": "50°31′02″N 3°56′27″W / 50.51719°N 3.94085°W / 50.51719; -3.94085",
"title": "Sources"
}
] | Childe's Tomb is a granite cross on Dartmoor, Devon, England. Although not in its original form, it is more elaborate than most of the crosses on Dartmoor, being raised upon a constructed base, and it is known that a kistvaen is underneath. A well-known legend attached to the site, first recorded in 1630 by Tristram Risdon, concerns a wealthy hunter, Childe, who became lost in a snow storm and supposedly died there despite disembowelling his horse and climbing into its body for protection. The legend relates that Childe left a note of some sort saying that whoever found and buried his body would inherit his lands at Plymstock. After a race between the monks of Tavistock Abbey and the men of Plymstock, the Abbey won. The tomb was virtually destroyed in 1812 by a man who stole most of the stones to build a house nearby, but it was partly reconstructed in 1890. | 2001-09-11T21:54:54Z | 2023-10-30T19:39:03Z | [
"Template:Short description",
"Template:Citation needed",
"Template:Reflist",
"Template:Cite book",
"Template:Refbegin",
"Template:Refend",
"Template:Coord",
"Template:Use dmy dates",
"Template:Gbmapping",
"Template:Convert",
"Template:Blockquote",
"Template:Cite web",
"Template:Cite journal"
] | https://en.wikipedia.org/wiki/Childe%27s_Tomb |
6,328 | Cognate | In historical linguistics, cognates or lexical cognates are sets of words that have been inherited in direct descent from an etymological ancestor in a common parent language. Because language change can have radical effects on both the sound and the meaning of a word, cognates may not be obvious, and often it takes rigorous study of historical sources and the application of the comparative method to establish whether lexemes are cognate. Cognates are distinguished from loanwords, where a word has been borrowed from another language.
The English term cognate derives from Latin cognatus, meaning "blood relative".
Cognates need not have the same meaning, which may have changed as the languages developed independently. For example English starve and Dutch sterven 'to die' or German sterben 'to die' all descend from the same Proto-Germanic verb, *sterbaną 'to die'.
Cognates also do not need to look or sound similar: English father, French père, and Armenian հայր (hayr) all descend directly from Proto-Indo-European *ph₂tḗr. An extreme case is Armenian երկու (erku) and English two, which descend from Proto-Indo-European *dwóh₁; the sound change *dw > erk in Armenian is regular.
An example of cognates from the same Indo-European root are: night (English), Nacht (German), nacht (Dutch, Frisian), nag (Afrikaans), Naach (Colognian), natt (Swedish, Norwegian), nat (Danish), nátt (Faroese), nótt (Icelandic), noc (Czech, Slovak, Polish), ночь, noch (Russian), ноќ, noć (Macedonian), нощ, nosht (Bulgarian), ніч, nich (Ukrainian), ноч, noch/noč (Belarusian), noč (Slovene), noć (Serbo-Croatian), nakts (Latvian), naktis (Lithuanian), nos (Welsh/Cymraeg), νύξ, nyx (Ancient Greek), νύχτα / nychta (Modern Greek), nakt- (Sanskrit), natë (Albanian), nox, gen. sg. noctis (Latin), nuit (French), noche (Spanish), nueche (Asturian), noite (Portuguese and Galician), notte (Italian), nit (Catalan), nuet/nit/nueit (Aragonese), nuèch / nuèit (Occitan) and noapte (Romanian). These all mean 'night' and derive from the Proto-Indo-European *nókʷts 'night'. The Indo-European languages have hundreds of such cognate sets, though few of them are as neat as this.
The Arabic سلام salām, the Hebrew שלום shalom, the Assyrian Neo-Aramaic shlama and the Amharic selam 'peace' are cognates, derived from the Proto-Semitic *šalām- 'peace'.
False cognates are pairs of words that appear to have a common origin, but which in fact do not. For example, Latin habēre and German haben both mean 'to have' and are phonetically similar. However, the words evolved from different Proto-Indo-European (PIE) roots: haben, like English have, comes from PIE *kh₂pyé- 'to grasp', and has the Latin cognate capere 'to seize, grasp, capture'. Habēre, on the other hand, is from PIE *gʰabʰ 'to give, to receive', and hence cognate with English give and German geben.
Likewise, English much and Spanish mucho look similar and have a similar meaning, but are not cognates: much is from Proto-Germanic *mikilaz < PIE *meǵ- and mucho is from Latin multum < PIE *mel-. A true cognate of much is the archaic Spanish maño 'big'.
Cognates are distinguished from other kinds of relationships.
An etymon, or ancestor word, is the ultimate source word from which one or more cognates derive. In other words, it is the source of related words in different languages. For example, the etymon of both Welsh ceffyl and Irish capall is the Proto-Celtic *kaballos (all meaning horse).
Descendants are words inherited across a language barrier, coming from a particular etymon in an ancestor language. For example, Russian мо́ре and Polish morze are both descendants of Proto-Slavic *moře (meaning sea).
A root is the source of related words within a single language. Similar to the distinction between etymon and root, a nuanced distinction can sometimes be made between a descendant and a derivative.
A derivative is one of the words which have their source in a root word, and were at some time created from the root word using morphological constructs such as suffixes, prefixes, and slight changes to the vowels or to the consonants of the root word. For example unhappy, happily, and unhappily are all derivatives of the root word happy.
The terms root and derivative are used in the analysis of morphological derivation within a language, in studies that are not concerned with historical linguistics, and that do not cross the language barrier. | [
{
"paragraph_id": 0,
"text": "In historical linguistics, cognates or lexical cognates are sets of words that have been inherited in direct descent from an etymological ancestor in a common parent language. Because language change can have radical effects on both the sound and the meaning of a word, cognates may not be obvious, and often it takes rigorous study of historical sources and the application of the comparative method to establish whether lexemes are cognate. Cognates are distinguished from loanwords, where a word has been borrowed from another language.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The English term cognate derives from Latin cognatus, meaning \"blood relative\".",
"title": "Name"
},
{
"paragraph_id": 2,
"text": "Cognates need not have the same meaning, which may have changed as the languages developed independently. For example English starve and Dutch sterven 'to die' or German sterben 'to die' all descend from the same Proto-Germanic verb, *sterbaną 'to die'.",
"title": "Characteristics"
},
{
"paragraph_id": 3,
"text": "Cognates also do not need to look or sound similar: English father, French père, and Armenian հայր (hayr) all descend directly from Proto-Indo-European *ph₂tḗr. An extreme case is Armenian երկու (erku) and English two, which descend from Proto-Indo-European *dwóh₁; the sound change *dw > erk in Armenian is regular.",
"title": "Characteristics"
},
{
"paragraph_id": 4,
"text": "An example of cognates from the same Indo-European root are: night (English), Nacht (German), nacht (Dutch, Frisian), nag (Afrikaans), Naach (Colognian), natt (Swedish, Norwegian), nat (Danish), nátt (Faroese), nótt (Icelandic), noc (Czech, Slovak, Polish), ночь, noch (Russian), ноќ, noć (Macedonian), нощ, nosht (Bulgarian), ніч, nich (Ukrainian), ноч, noch/noč (Belarusian), noč (Slovene), noć (Serbo-Croatian), nakts (Latvian), naktis (Lithuanian), nos (Welsh/Cymraeg), νύξ, nyx (Ancient Greek), νύχτα / nychta (Modern Greek), nakt- (Sanskrit), natë (Albanian), nox, gen. sg. noctis (Latin), nuit (French), noche (Spanish), nueche (Asturian), noite (Portuguese and Galician), notte (Italian), nit (Catalan), nuet/nit/nueit (Aragonese), nuèch / nuèit (Occitan) and noapte (Romanian). These all mean 'night' and derive from the Proto-Indo-European *nókʷts 'night'. The Indo-European languages have hundreds of such cognate sets, though few of them are as neat as this.",
"title": "Characteristics"
},
{
"paragraph_id": 5,
"text": "The Arabic سلام salām, the Hebrew שלום shalom, the Assyrian Neo-Aramaic shlama and the Amharic selam 'peace' are cognates, derived from the Proto-Semitic *šalām- 'peace'.",
"title": "Characteristics"
},
{
"paragraph_id": 6,
"text": "False cognates are pairs of words that appear to have a common origin, but which in fact do not. For example, Latin habēre and German haben both mean 'to have' and are phonetically similar. However, the words evolved from different Proto-Indo-European (PIE) roots: haben, like English have, comes from PIE *kh₂pyé- 'to grasp', and has the Latin cognate capere 'to seize, grasp, capture'. Habēre, on the other hand, is from PIE *gʰabʰ 'to give, to receive', and hence cognate with English give and German geben.",
"title": "False cognates"
},
{
"paragraph_id": 7,
"text": "Likewise, English much and Spanish mucho look similar and have a similar meaning, but are not cognates: much is from Proto-Germanic *mikilaz < PIE *meǵ- and mucho is from Latin multum < PIE *mel-. A true cognate of much is the archaic Spanish maño 'big'.",
"title": "False cognates"
},
{
"paragraph_id": 8,
"text": "Cognates are distinguished from other kinds of relationships.",
"title": "Distinctions"
},
{
"paragraph_id": 9,
"text": "An etymon, or ancestor word, is the ultimate source word from which one or more cognates derive. In other words, it is the source of related words in different languages. For example, the etymon of both Welsh ceffyl and Irish capall is the Proto-Celtic *kaballos (all meaning horse).",
"title": "Related terms"
},
{
"paragraph_id": 10,
"text": "Descendants are words inherited across a language barrier, coming from a particular etymon in an ancestor language. For example, Russian мо́ре and Polish morze are both descendants of Proto-Slavic *moře (meaning sea).",
"title": "Related terms"
},
{
"paragraph_id": 11,
"text": "A root is the source of related words within a single language. Similar to the distinction between etymon and root, a nuanced distinction can sometimes be made between a descendant and a derivative.",
"title": "Related terms"
},
{
"paragraph_id": 12,
"text": "A derivative is one of the words which have their source in a root word, and were at some time created from the root word using morphological constructs such as suffixes, prefixes, and slight changes to the vowels or to the consonants of the root word. For example unhappy, happily, and unhappily are all derivatives of the root word happy.",
"title": "Related terms"
},
{
"paragraph_id": 13,
"text": "The terms root and derivative are used in the analysis of morphological derivation within a language, in studies that are not concerned with historical linguistics, and that do not cross the language barrier.",
"title": "Related terms"
}
] | In historical linguistics, cognates or lexical cognates are sets of words that have been inherited in direct descent from an etymological ancestor in a common parent language. Because language change can have radical effects on both the sound and the meaning of a word, cognates may not be obvious, and often it takes rigorous study of historical sources and the application of the comparative method to establish whether lexemes are cognate. Cognates are distinguished from loanwords, where a word has been borrowed from another language. | 2001-09-12T15:41:03Z | 2023-12-31T16:02:25Z | [
"Template:Cite book",
"Template:Wiktionary",
"Template:Reflist",
"Template:Other uses",
"Template:Use dmy dates",
"Template:Anchor",
"Template:Lang",
"Template:PIE",
"Template:Script/Hebrew",
"Template:Main",
"Template:Short description",
"Template:Cite web",
"Template:Portal"
] | https://en.wikipedia.org/wiki/Cognate |
6,329 | Chromatography | In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the mobile phase, which carries it through a system (a column, a capillary tube, a plate, or a sheet) on which a material called the stationary phase is fixed. Because the different constituents of the mixture tend to have different affinities for the stationary phase and are retained for different lengths of time depending on their interactions with its surface sites, the constituents travel at different apparent velocities in the mobile fluid, causing them to separate. The separation is based on the differential partitioning between the mobile and the stationary phases. Subtle differences in a compound's partition coefficient result in differential retention on the stationary phase and thus affect the separation.
Chromatography may be preparative or analytical. The purpose of preparative chromatography is to separate the components of a mixture for later use, and is thus a form of purification. This process is associated with higher costs due to its mode of production. Analytical chromatography is done normally with smaller amounts of material and is for establishing the presence or measuring the relative proportions of analytes in a mixture. The two types are not mutually exclusive.
Chromatography, pronounced /ˌkroʊməˈtɒɡrəfi/, is derived from Greek χρῶμα chroma, which means "color", and γράφειν graphein, which means "to write". The combination of these two terms was directly inherited from the invention of the technique first used to separate pigments.
Chromatography was first devised at the University of Kazan by the Italian-born Russian scientist Mikhail Tsvet in 1900. He developed the technique and coined the term chromatography in the first decade of the 20th century, primarily for the separation of plant pigments such as chlorophyll, carotenes, and xanthophylls. Since these components separate in bands of different colors (green, orange, and yellow, respectively) they directly inspired the name of the technique. New types of chromatography developed during the 1930s and 1940s made the technique useful for many separation processes.
Chromatography technique developed substantially as a result of the work of Archer John Porter Martin and Richard Laurence Millington Synge during the 1940s and 1950s, for which they won the 1952 Nobel Prize in Chemistry. They established the principles and basic techniques of partition chromatography, and their work encouraged the rapid development of several chromatographic methods: paper chromatography, gas chromatography, and what would become known as high-performance liquid chromatography. Since then, the technology has advanced rapidly. Researchers found that the main principles of Tsvet's chromatography could be applied in many different ways, resulting in the different varieties of chromatography described below. Advances are continually improving the technical performance of chromatography, allowing the separation of increasingly similar molecules.
Chromatography is based on the concept of partition coefficient. Any solute partitions between two immiscible solvents. When we make one solvent immobile (by adsorption on a solid support matrix) and another mobile it results in most common applications of chromatography. If the matrix support, or stationary phase, is polar (e.g. paper, silica etc.) it is forward phase chromatography, and if it is non-polar (C-18) it is reverse phase.
Column chromatography is a separation technique in which the stationary bed is within a tube. The particles of the solid stationary phase or the support coated with a liquid stationary phase may fill the whole inside volume of the tube (packed column) or be concentrated on or along the inside tube wall leaving an open, unrestricted path for the mobile phase in the middle part of the tube (open tubular column). Differences in rates of movement through the medium are calculated to different retention times of the sample. In 1978, W. Clark Still introduced a modified version of column chromatography called flash column chromatography (flash). The technique is very similar to the traditional column chromatography, except that the solvent is driven through the column by applying positive pressure. This allowed most separations to be performed in less than 20 minutes, with improved separations compared to the old method. Modern flash chromatography systems are sold as pre-packed plastic cartridges, and the solvent is pumped through the cartridge. Systems may also be linked with detectors and fraction collectors providing automation. The introduction of gradient pumps resulted in quicker separations and less solvent usage.
In expanded bed adsorption, a fluidized bed is used, rather than a solid phase made by a packed bed. This allows omission of initial clearing steps such as centrifugation and filtration, for culture broths or slurries of broken cells.
Phosphocellulose chromatography utilizes the binding affinity of many DNA-binding proteins for phosphocellulose. The stronger a protein's interaction with DNA, the higher the salt concentration needed to elute that protein.
Planar chromatography is a separation technique in which the stationary phase is present as or on a plane. The plane can be a paper, serving as such or impregnated by a substance as the stationary bed (paper chromatography) or a layer of solid particles spread on a support such as a glass plate (thin-layer chromatography). Different compounds in the sample mixture travel different distances according to how strongly they interact with the stationary phase as compared to the mobile phase. The specific Retention factor (Rf) of each chemical can be used to aid in the identification of an unknown substance.
Paper chromatography is a technique that involves placing a small dot or line of sample solution onto a strip of chromatography paper. The paper is placed in a container with a shallow layer of solvent and sealed. As the solvent rises through the paper, it meets the sample mixture, which starts to travel up the paper with the solvent. This paper is made of cellulose, a polar substance, and the compounds within the mixture travel further if they are less polar. More polar substances bond with the cellulose paper more quickly, and therefore do not travel as far
Thin-layer chromatography (TLC) is a widely employed laboratory technique used to separate different biochemicals on the basis of their relative attractions to the stationary and mobile phases. It is similar to paper chromatography. However, instead of using a stationary phase of paper, it involves a stationary phase of a thin layer of adsorbent like silica gel, alumina, or cellulose on a flat, inert substrate. TLC is very versatile; multiple samples can be separated simultaneously on the same layer, making it very useful for screening applications such as testing drug levels and water purity.
Possibility of cross-contamination is low since each separation is performed on a new layer. Compared to paper, it has the advantage of faster runs, better separations, better quantitative analysis, and the choice between different adsorbents. For even better resolution and faster separation that utilizes less solvent, high-performance TLC can be used. An older popular use had been to differentiate chromosomes by observing distance in gel (separation of was a separate step).
The basic principle of displacement chromatography is: A molecule with a high affinity for the chromatography matrix (the displacer) competes effectively for binding sites, and thus displaces all molecules with lesser affinities. There are distinct differences between displacement and elution chromatography. In elution mode, substances typically emerge from a column in narrow, Gaussian peaks. Wide separation of peaks, preferably to baseline, is desired for maximum purification. The speed at which any component of a mixture travels down the column in elution mode depends on many factors. But for two substances to travel at different speeds, and thereby be resolved, there must be substantial differences in some interaction between the biomolecules and the chromatography matrix. Operating parameters are adjusted to maximize the effect of this difference. In many cases, baseline separation of the peaks can be achieved only with gradient elution and low column loadings. Thus, two drawbacks to elution mode chromatography, especially at the preparative scale, are operational complexity, due to gradient solvent pumping, and low throughput, due to low column loadings. Displacement chromatography has advantages over elution chromatography in that components are resolved into consecutive zones of pure substances rather than "peaks". Because the process takes advantage of the nonlinearity of the isotherms, a larger column feed can be separated on a given column with the purified components recovered at significantly higher concentrations.
Gas chromatography (GC), also sometimes known as gas-liquid chromatography, (GLC), is a separation technique in which the mobile phase is a gas. Gas chromatographic separation is always carried out in a column, which is typically "packed" or "capillary". Packed columns are the routine work horses of gas chromatography, being cheaper and easier to use and often giving adequate performance. Capillary columns generally give far superior resolution and although more expensive are becoming widely used, especially for complex mixtures. Further, capillary columns can be split into three classes: porous layer open tubular (PLOT), wall-coated open tubular (WCOT) and support-coated open tubular (SCOT) columns. PLOT columns are unique in a way that the stationary phase is adsorbed to the column walls, while WCOT columns have a stationary phase that is chemically bonded to the walls. SCOT columns are in a way the combination of the two types mentioned in a way that they have support particles adhered to column walls, but those particles have liquid phase chemically bonded onto them. Both types of column are made from non-adsorbent and chemically inert materials. Stainless steel and glass are the usual materials for packed columns and quartz or fused silica for capillary columns.
Gas chromatography is based on a partition equilibrium of analyte between a solid or viscous liquid stationary phase (often a liquid silicone-based material) and a mobile gas (most often helium). The stationary phase is adhered to the inside of a small-diameter (commonly 0.53 – 0.18mm inside diameter) glass or fused-silica tube (a capillary column) or a solid matrix inside a larger metal tube (a packed column). It is widely used in analytical chemistry; though the high temperatures used in GC make it unsuitable for high molecular weight biopolymers or proteins (heat denatures them), frequently encountered in biochemistry, it is well suited for use in the petrochemical, environmental monitoring and remediation, and industrial chemical fields. It is also used extensively in chemistry research.
Liquid chromatography (LC) is a separation technique in which the mobile phase is a liquid. It can be carried out either in a column or a plane. Present day liquid chromatography that generally utilizes very small packing particles and a relatively high pressure is referred to as high-performance liquid chromatography.
In HPLC the sample is forced by a liquid at high pressure (the mobile phase) through a column that is packed with a stationary phase composed of irregularly or spherically shaped particles, a porous monolithic layer, or a porous membrane. Monoliths are "sponge-like chromatographic media" and are made up of an unending block of organic or inorganic parts. HPLC is historically divided into two different sub-classes based on the polarity of the mobile and stationary phases. Methods in which the stationary phase is more polar than the mobile phase (e.g., toluene as the mobile phase, silica as the stationary phase) are termed normal phase liquid chromatography (NPLC) and the opposite (e.g., water-methanol mixture as the mobile phase and C18 (octadecylsilyl) as the stationary phase) is termed reversed phase liquid chromatography (RPLC).
Supercritical fluid chromatography is a separation technique in which the mobile phase is a fluid above and relatively close to its critical temperature and pressure.
Specific techniques under this broad heading are listed below.
Affinity chromatography is based on selective non-covalent interaction between an analyte and specific molecules. It is very specific, but not very robust. It is often used in biochemistry in the purification of proteins bound to tags. These fusion proteins are labeled with compounds such as His-tags, biotin or antigens, which bind to the stationary phase specifically. After purification, these tags are usually removed and the pure protein is obtained.
Affinity chromatography often utilizes a biomolecule's affinity for a metal (Zn, Cu, Fe, etc.). Columns are often manually prepared and could be designed specifically for the proteins of interest. Traditional affinity columns are used as a preparative step to flush out unwanted biomolecules, or as a primary step in analyzing a protein with unknown physical properties.
However, liquid chromatography techniques exist that do utilize affinity chromatography properties. Immobilized metal affinity chromatography (IMAC) is useful to separate the aforementioned molecules based on the relative affinity for the metal. Often these columns can be loaded with different metals to create a column with a targeted affinity.
Ion exchange chromatography (usually referred to as ion chromatography) uses an ion exchange mechanism to separate analytes based on their respective charges. It is usually performed in columns but can also be useful in planar mode. Ion exchange chromatography uses a charged stationary phase to separate charged compounds including anions, cations, amino acids, peptides, and proteins. In conventional methods the stationary phase is an ion-exchange resin that carries charged functional groups that interact with oppositely charged groups of the compound to retain. There are two types of ion exchange chromatography: Cation-Exchange and Anion-Exchange. In the Cation-Exchange Chromatography the stationary phase has negative charge and the exchangeable ion is a cation, whereas, in the Anion-Exchange Chromatography the stationary phase has positive charge and the exchangeable ion is an anion. Ion exchange chromatography is commonly used to purify proteins using FPLC.
Size-exclusion chromatography (SEC) is also known as gel permeation chromatography (GPC) or gel filtration chromatography and separates molecules according to their size (or more accurately according to their hydrodynamic diameter or hydrodynamic volume). Smaller molecules are able to enter the pores of the media and, therefore, molecules are trapped and removed from the flow of the mobile phase. The average residence time in the pores depends upon the effective size of the analyte molecules. However, molecules that are larger than the average pore size of the packing are excluded and thus suffer essentially no retention; such species are the first to be eluted. It is generally a low-resolution chromatography technique and thus it is often reserved for the final, "polishing" step of a purification. It is also useful for determining the tertiary structure and quaternary structure of purified proteins, especially since it can be carried out under native solution conditions.
An expanded bed chromatographic adsorption (EBA) column for a biochemical separation process comprises a pressure equalization liquid distributor having a self-cleaning function below a porous blocking sieve plate at the bottom of the expanded bed, an upper part nozzle assembly having a backflush cleaning function at the top of the expanded bed, a better distribution of the feedstock liquor added into the expanded bed ensuring that the fluid passed through the expanded bed layer displays a state of piston flow. The expanded bed layer displays a state of piston flow. The expanded bed chromatographic separation column has advantages of increasing the separation efficiency of the expanded bed.
Expanded-bed adsorption (EBA) chromatography is a convenient and effective technique for the capture of proteins directly from unclarified crude sample. In EBA chromatography, the settled bed is first expanded by upward flow of equilibration buffer. The crude feed, a mixture of soluble proteins, contaminants, cells, and cell debris, is then passed upward through the expanded bed. Target proteins are captured on the adsorbent, while particulates and contaminants pass through. A change to elution buffer while maintaining upward flow results in desorption of the target protein in expanded-bed mode. Alternatively, if the flow is reversed, the adsorbed particles will quickly settle and the proteins can be desorbed by an elution buffer. The mode used for elution (expanded-bed versus settled-bed) depends on the characteristics of the feed. After elution, the adsorbent is cleaned with a predefined cleaning-in-place (CIP) solution, with cleaning followed by either column regeneration (for further use) or storage.
Reversed-phase chromatography (RPC) is any liquid chromatography procedure in which the mobile phase is significantly more polar than the stationary phase. It is so named because in normal-phase liquid chromatography, the mobile phase is significantly less polar than the stationary phase. Hydrophobic molecules in the mobile phase tend to adsorb to the relatively hydrophobic stationary phase. Hydrophilic molecules in the mobile phase will tend to elute first. Separating columns typically comprise a C8 or C18 carbon-chain bonded to a silica particle substrate.
Hydrophobic Interaction Chromatography (HIC) is a purification and analytical technique that separates analytes, such as proteins, based on hydrophobic interactions between that analyte and the chromatographic matrix. It can provide a non-denaturing orthogonal approach to reversed phase separation, preserving native structures and potentially protein activity. In hydrophobic interaction chromatography, the matrix material is lightly substituted with hydrophobic groups. These groups can range from methyl, ethyl, propyl, butyl, octyl, or phenyl groups. At high salt concentrations, non-polar sidechains on the surface on proteins "interact" with the hydrophobic groups; that is, both types of groups are excluded by the polar solvent (hydrophobic effects are augmented by increased ionic strength). Thus, the sample is applied to the column in a buffer which is highly polar, which drives an association of hydrophobic patches on the analyte with the stationary phase. The eluent is typically an aqueous buffer with decreasing salt concentrations, increasing concentrations of detergent (which disrupts hydrophobic interactions), or changes in pH. Of critical importance is the type of salt used, with more kosmotropic salts as defined by the Hofmeister series providing the most water structuring around the molecule and resulting hydrophobic pressure. Ammonium sulfate is frequently used for this purpose. The addition of organic solvents or other less polar constituents may assist in improving resolution.
In general, Hydrophobic Interaction Chromatography (HIC) is advantageous if the sample is sensitive to pH change or harsh solvents typically used in other types of chromatography but not high salt concentrations. Commonly, it is the amount of salt in the buffer which is varied. In 2012, Müller and Franzreb described the effects of temperature on HIC using Bovine Serum Albumin (BSA) with four different types of hydrophobic resin. The study altered temperature as to effect the binding affinity of BSA onto the matrix. It was concluded that cycling temperature from 50 to 10 degrees would not be adequate to effectively wash all BSA from the matrix but could be very effective if the column would only be used a few times. Using temperature to effect change allows labs to cut costs on buying salt and saves money.
If high salt concentrations along with temperature fluctuations want to be avoided you can use a more hydrophobic to compete with your sample to elute it. [source] This so-called salt independent method of HIC showed a direct isolation of Human Immunoglobulin G (IgG) from serum with satisfactory yield and used Beta-cyclodextrin as a competitor to displace IgG from the matrix. This largely opens up the possibility of using HIC with samples which are salt sensitive as we know high salt concentrations precipitate proteins.
Hydrodynamic chromatography (HDC) is derived from the observed phenomenon that large droplets move faster than small ones. In a column, this happens because the center of mass of larger droplets is prevented from being as close to the sides of the column as smaller droplets because of their larger overall size. Larger droplets will elute first from the middle of the column while smaller droplets stick to the sides of the column and elute last. This form of chromatography is useful for separating analytes by molar mass, size, shape, and structure when used in conjunction with light scattering detectors, viscometers, and refractometers. The two main types of HDC are open tube and packed column. Open tube offers rapid separation times for small particles, whereas packed column HDC can increase resolution and is better suited for particles with an average molecular mass larger than 10 5 {\displaystyle 10^{5}} daltons. HDC differs from other types of chromatography because the separation only takes place in the interstitial volume, which is the volume surrounding and in between particles in a packed column.
HDC shares the same order of elution as Size Exclusion Chromatography (SEC) but the two processes still vary in many ways. In a study comparing the two types of separation, Isenberg, Brewer, Côté, and Striegel use both methods for polysaccharide characterization and conclude that HDC coupled with multiangle light scattering (MALS) achieves more accurate molar mass distribution when compared to off-line MALS than SEC in significantly less time. This is largely due to SEC being a more destructive technique because of the pores in the column degrading the analyte during separation, which tends to impact the mass distribution. However, the main disadvantage of HDC is low resolution of analyte peaks, which makes SEC a more viable option when used with chemicals that are not easily degradable and where rapid elution is not important.
HDC plays an especially important role in the field of microfluidics. The first successful apparatus for HDC-on-a-chip system was proposed by Chmela, et al. in 2002. Their design was able to achieve separations using an 80 mm long channel on the timescale of 3 minutes for particles with diameters ranging from 26 to 110 nm, but the authors expressed a need to improve the retention and dispersion parameters. In a 2010 publication by Jellema, Markesteijn, Westerweel, and Verpoorte, implementing HDC with a recirculating bidirectional flow resulted in high resolution, size based separation with only a 3 mm long channel. Having such a short channel and high resolution was viewed as especially impressive considering that previous studies used channels that were 80 mm in length. For a biological application, in 2007, Huh, et al. proposed a microfluidic sorting device based on HDC and gravity, which was useful for preventing potentially dangerous particles with diameter larger than 6 microns from entering the bloodstream when injecting contrast agents in ultrasounds. This study also made advances for environmental sustainability in microfluidics due to the lack of outside electronics driving the flow, which came as an advantage of using a gravity based device.
In some cases, the selectivity provided by the use of one column can be insufficient to provide resolution of analytes in complex samples. Two-dimensional chromatography aims to increase the resolution of these peaks by using a second column with different physico-chemical (chemical classification) properties. Since the mechanism of retention on this new solid support is different from the first dimensional separation, it can be possible to separate compounds by two-dimensional chromatography that are indistinguishable by one-dimensional chromatography. Furthermore, the separation on the second dimension occurs faster than the first dimension. An example of a two-dimensional TLC separation is where the sample is spotted at one corner of a square plate, developed, air-dried, then rotated by 90° and usually redeveloped in a second solvent system. Two-dimensional chromatography can be applied to GC or LC separations. This separation method can also be used in a heart-cutting approach, where specific regions of interest on the first dimension are selected for separation by the second dimension, or in a comprehensive approach, where all the analytes from the first dimension undergo the second dimension separation.
The simulated moving bed (SMB) technique is a variant of high performance liquid chromatography; it is used to separate particles and/or chemical compounds that would be difficult or impossible to resolve otherwise. This increased separation is brought about by a valve-and-column arrangement that is used to lengthen the stationary phase indefinitely. In the moving bed technique of preparative chromatography the feed entry and the analyte recovery are simultaneous and continuous, but because of practical difficulties with a continuously moving bed, simulated moving bed technique was proposed. In the simulated moving bed technique instead of moving the bed, the sample inlet and the analyte exit positions are moved continuously, giving the impression of a moving bed. True moving bed chromatography (TMBC) is only a theoretical concept. Its simulation, SMBC is achieved by the use of a multiplicity of columns in series and a complex valve arrangement, which provides for sample and solvent feed, and also analyte and waste takeoff at appropriate locations of any column, whereby it allows switching at regular intervals the sample entry in one direction, the solvent entry in the opposite direction, whilst changing the analyte and waste takeoff positions appropriately as well.
Pyrolysis–gas chromatography–mass spectrometry is a method of chemical analysis in which the sample is heated to decomposition to produce smaller molecules that are separated by gas chromatography and detected using mass spectrometry.
Pyrolysis is the thermal decomposition of materials in an inert atmosphere or a vacuum. The sample is put into direct contact with a platinum wire, or placed in a quartz sample tube, and rapidly heated to 600–1000 °C. Depending on the application even higher temperatures are used. Three different heating techniques are used in actual pyrolyzers: Isothermal furnace, inductive heating (Curie Point filament), and resistive heating using platinum filaments. Large molecules cleave at their weakest points and produce smaller, more volatile fragments. These fragments can be separated by gas chromatography. Pyrolysis GC chromatograms are typically complex because a wide range of different decomposition products is formed. The data can either be used as fingerprints to prove material identity or the GC/MS data is used to identify individual fragments to obtain structural information. To increase the volatility of polar fragments, various methylating reagents can be added to a sample before pyrolysis.
Besides the usage of dedicated pyrolyzers, pyrolysis GC of solid and liquid samples can be performed directly inside Programmable Temperature Vaporizer (PTV) injectors that provide quick heating (up to 30 °C/s) and high maximum temperatures of 600–650 °C. This is sufficient for some pyrolysis applications. The main advantage is that no dedicated instrument has to be purchased and pyrolysis can be performed as part of routine GC analysis. In this case, quartz GC inlet liners have to be used. Quantitative data can be acquired, and good results of derivatization inside the PTV injector are published as well.
Fast protein liquid chromatography (FPLC), is a form of liquid chromatography that is often used to analyze or purify mixtures of proteins. As in other forms of chromatography, separation is possible because the different components of a mixture have different affinities for two materials, a moving fluid (the "mobile phase") and a porous solid (the stationary phase). In FPLC the mobile phase is an aqueous solution, or "buffer". The buffer flow rate is controlled by a positive-displacement pump and is normally kept constant, while the composition of the buffer can be varied by drawing fluids in different proportions from two or more external reservoirs. The stationary phase is a resin composed of beads, usually of cross-linked agarose, packed into a cylindrical glass or plastic column. FPLC resins are available in a wide range of bead sizes and surface ligands depending on the application.
Countercurrent chromatography (CCC) is a type of liquid-liquid chromatography, where both the stationary and mobile phases are liquids and the liquid stationary phase is held stagnant by a strong centrifugal force.
The operating principle of CCC instrument requires a column consisting of an open tube coiled around a bobbin. The bobbin is rotated in a double-axis gyratory motion (a cardioid), which causes a variable gravity (G) field to act on the column during each rotation. This motion causes the column to see one partitioning step per revolution and components of the sample separate in the column due to their partitioning coefficient between the two immiscible liquid phases used. There are many types of CCC available today. These include HSCCC (High Speed CCC) and HPCCC (High Performance CCC). HPCCC is the latest and best-performing version of the instrumentation available currently.
In the CPC (centrifugal partition chromatography or hydrostatic countercurrent chromatography) instrument, the column consists of a series of cells interconnected by ducts attached to a rotor. This rotor rotates on its central axis creating the centrifugal field necessary to hold the stationary phase in place. The separation process in CPC is governed solely by the partitioning of solutes between the stationary and mobile phases, which mechanism can be easily described using the partition coefficients (KD) of solutes. CPC instruments are commercially available for laboratory, pilot, and industrial-scale separations with different sizes of columns ranging from some 10 milliliters to 10 liters volume.
In contrast to Counter current chromatography (see above), periodic counter-current chromatography (PCC) uses a solid stationary phase and only a liquid mobile phase. It thus is much more similar to conventional affinity chromatography than to counter current chromatography. PCC uses multiple columns, which during the loading phase are connected in line. This mode allows for overloading the first column in this series without losing product, which already breaks through the column before the resin is fully saturated. The breakthrough product is captured on the subsequent column(s). In a next step the columns are disconnected from one another. The first column is washed and eluted, while the other column(s) are still being loaded. Once the (initially) first column is re-equilibrated, it is re-introduced to the loading stream, but as last column. The process then continues in a cyclic fashion.
Chiral chromatography involves the separation of stereoisomers. In the case of enantiomers, these have no chemical or physical differences apart from being three-dimensional mirror images. To enable chiral separations to take place, either the mobile phase or the stationary phase must themselves be made chiral, giving differing affinities between the analytes. Chiral chromatography HPLC columns (with a chiral stationary phase) in both normal and reversed phase are commercially available.
Conventional chromatography are incapable of separating racemic mixtures of enantiomers. However, in some cases nonracemic mixtures of enantiomers may be separated unexpectedly by conventional liquid chromatography (e. g. HPLC without chiral mobile phase or stationary phase ).
Aqueous normal-phase (ANP) chromatography is characterized by the elution behavior of classical normal phase mode (i.e. where the mobile phase is significantly less polar than the stationary phase) in which water is one of the mobile phase solvent system components. It is distinguished from hydrophilic interaction liquid chromatography (HILIC) in that the retention mechanism is due to adsorption rather than partitioning.
Chromatography is used in many fields including the pharmaceutical industry, the food and beverage industry, the chemical industry, forensic science, environment analysis, and hospitals. | [
{
"paragraph_id": 0,
"text": "In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the mobile phase, which carries it through a system (a column, a capillary tube, a plate, or a sheet) on which a material called the stationary phase is fixed. Because the different constituents of the mixture tend to have different affinities for the stationary phase and are retained for different lengths of time depending on their interactions with its surface sites, the constituents travel at different apparent velocities in the mobile fluid, causing them to separate. The separation is based on the differential partitioning between the mobile and the stationary phases. Subtle differences in a compound's partition coefficient result in differential retention on the stationary phase and thus affect the separation.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Chromatography may be preparative or analytical. The purpose of preparative chromatography is to separate the components of a mixture for later use, and is thus a form of purification. This process is associated with higher costs due to its mode of production. Analytical chromatography is done normally with smaller amounts of material and is for establishing the presence or measuring the relative proportions of analytes in a mixture. The two types are not mutually exclusive.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Chromatography, pronounced /ˌkroʊməˈtɒɡrəfi/, is derived from Greek χρῶμα chroma, which means \"color\", and γράφειν graphein, which means \"to write\". The combination of these two terms was directly inherited from the invention of the technique first used to separate pigments.",
"title": "Etymology and pronunciation"
},
{
"paragraph_id": 3,
"text": "Chromatography was first devised at the University of Kazan by the Italian-born Russian scientist Mikhail Tsvet in 1900. He developed the technique and coined the term chromatography in the first decade of the 20th century, primarily for the separation of plant pigments such as chlorophyll, carotenes, and xanthophylls. Since these components separate in bands of different colors (green, orange, and yellow, respectively) they directly inspired the name of the technique. New types of chromatography developed during the 1930s and 1940s made the technique useful for many separation processes.",
"title": "History"
},
{
"paragraph_id": 4,
"text": "Chromatography technique developed substantially as a result of the work of Archer John Porter Martin and Richard Laurence Millington Synge during the 1940s and 1950s, for which they won the 1952 Nobel Prize in Chemistry. They established the principles and basic techniques of partition chromatography, and their work encouraged the rapid development of several chromatographic methods: paper chromatography, gas chromatography, and what would become known as high-performance liquid chromatography. Since then, the technology has advanced rapidly. Researchers found that the main principles of Tsvet's chromatography could be applied in many different ways, resulting in the different varieties of chromatography described below. Advances are continually improving the technical performance of chromatography, allowing the separation of increasingly similar molecules.",
"title": "History"
},
{
"paragraph_id": 5,
"text": "Chromatography is based on the concept of partition coefficient. Any solute partitions between two immiscible solvents. When we make one solvent immobile (by adsorption on a solid support matrix) and another mobile it results in most common applications of chromatography. If the matrix support, or stationary phase, is polar (e.g. paper, silica etc.) it is forward phase chromatography, and if it is non-polar (C-18) it is reverse phase.",
"title": "Chromatography terms"
},
{
"paragraph_id": 6,
"text": "",
"title": "Techniques by chromatographic bed shape"
},
{
"paragraph_id": 7,
"text": "Column chromatography is a separation technique in which the stationary bed is within a tube. The particles of the solid stationary phase or the support coated with a liquid stationary phase may fill the whole inside volume of the tube (packed column) or be concentrated on or along the inside tube wall leaving an open, unrestricted path for the mobile phase in the middle part of the tube (open tubular column). Differences in rates of movement through the medium are calculated to different retention times of the sample. In 1978, W. Clark Still introduced a modified version of column chromatography called flash column chromatography (flash). The technique is very similar to the traditional column chromatography, except that the solvent is driven through the column by applying positive pressure. This allowed most separations to be performed in less than 20 minutes, with improved separations compared to the old method. Modern flash chromatography systems are sold as pre-packed plastic cartridges, and the solvent is pumped through the cartridge. Systems may also be linked with detectors and fraction collectors providing automation. The introduction of gradient pumps resulted in quicker separations and less solvent usage.",
"title": "Techniques by chromatographic bed shape"
},
{
"paragraph_id": 8,
"text": "In expanded bed adsorption, a fluidized bed is used, rather than a solid phase made by a packed bed. This allows omission of initial clearing steps such as centrifugation and filtration, for culture broths or slurries of broken cells.",
"title": "Techniques by chromatographic bed shape"
},
{
"paragraph_id": 9,
"text": "Phosphocellulose chromatography utilizes the binding affinity of many DNA-binding proteins for phosphocellulose. The stronger a protein's interaction with DNA, the higher the salt concentration needed to elute that protein.",
"title": "Techniques by chromatographic bed shape"
},
{
"paragraph_id": 10,
"text": "Planar chromatography is a separation technique in which the stationary phase is present as or on a plane. The plane can be a paper, serving as such or impregnated by a substance as the stationary bed (paper chromatography) or a layer of solid particles spread on a support such as a glass plate (thin-layer chromatography). Different compounds in the sample mixture travel different distances according to how strongly they interact with the stationary phase as compared to the mobile phase. The specific Retention factor (Rf) of each chemical can be used to aid in the identification of an unknown substance.",
"title": "Techniques by chromatographic bed shape"
},
{
"paragraph_id": 11,
"text": "Paper chromatography is a technique that involves placing a small dot or line of sample solution onto a strip of chromatography paper. The paper is placed in a container with a shallow layer of solvent and sealed. As the solvent rises through the paper, it meets the sample mixture, which starts to travel up the paper with the solvent. This paper is made of cellulose, a polar substance, and the compounds within the mixture travel further if they are less polar. More polar substances bond with the cellulose paper more quickly, and therefore do not travel as far",
"title": "Techniques by chromatographic bed shape"
},
{
"paragraph_id": 12,
"text": "Thin-layer chromatography (TLC) is a widely employed laboratory technique used to separate different biochemicals on the basis of their relative attractions to the stationary and mobile phases. It is similar to paper chromatography. However, instead of using a stationary phase of paper, it involves a stationary phase of a thin layer of adsorbent like silica gel, alumina, or cellulose on a flat, inert substrate. TLC is very versatile; multiple samples can be separated simultaneously on the same layer, making it very useful for screening applications such as testing drug levels and water purity.",
"title": "Techniques by chromatographic bed shape"
},
{
"paragraph_id": 13,
"text": "Possibility of cross-contamination is low since each separation is performed on a new layer. Compared to paper, it has the advantage of faster runs, better separations, better quantitative analysis, and the choice between different adsorbents. For even better resolution and faster separation that utilizes less solvent, high-performance TLC can be used. An older popular use had been to differentiate chromosomes by observing distance in gel (separation of was a separate step).",
"title": "Techniques by chromatographic bed shape"
},
{
"paragraph_id": 14,
"text": "The basic principle of displacement chromatography is: A molecule with a high affinity for the chromatography matrix (the displacer) competes effectively for binding sites, and thus displaces all molecules with lesser affinities. There are distinct differences between displacement and elution chromatography. In elution mode, substances typically emerge from a column in narrow, Gaussian peaks. Wide separation of peaks, preferably to baseline, is desired for maximum purification. The speed at which any component of a mixture travels down the column in elution mode depends on many factors. But for two substances to travel at different speeds, and thereby be resolved, there must be substantial differences in some interaction between the biomolecules and the chromatography matrix. Operating parameters are adjusted to maximize the effect of this difference. In many cases, baseline separation of the peaks can be achieved only with gradient elution and low column loadings. Thus, two drawbacks to elution mode chromatography, especially at the preparative scale, are operational complexity, due to gradient solvent pumping, and low throughput, due to low column loadings. Displacement chromatography has advantages over elution chromatography in that components are resolved into consecutive zones of pure substances rather than \"peaks\". Because the process takes advantage of the nonlinearity of the isotherms, a larger column feed can be separated on a given column with the purified components recovered at significantly higher concentrations.",
"title": "Displacement chromatography"
},
{
"paragraph_id": 15,
"text": "Gas chromatography (GC), also sometimes known as gas-liquid chromatography, (GLC), is a separation technique in which the mobile phase is a gas. Gas chromatographic separation is always carried out in a column, which is typically \"packed\" or \"capillary\". Packed columns are the routine work horses of gas chromatography, being cheaper and easier to use and often giving adequate performance. Capillary columns generally give far superior resolution and although more expensive are becoming widely used, especially for complex mixtures. Further, capillary columns can be split into three classes: porous layer open tubular (PLOT), wall-coated open tubular (WCOT) and support-coated open tubular (SCOT) columns. PLOT columns are unique in a way that the stationary phase is adsorbed to the column walls, while WCOT columns have a stationary phase that is chemically bonded to the walls. SCOT columns are in a way the combination of the two types mentioned in a way that they have support particles adhered to column walls, but those particles have liquid phase chemically bonded onto them. Both types of column are made from non-adsorbent and chemically inert materials. Stainless steel and glass are the usual materials for packed columns and quartz or fused silica for capillary columns.",
"title": "Techniques by physical state of mobile phase"
},
{
"paragraph_id": 16,
"text": "Gas chromatography is based on a partition equilibrium of analyte between a solid or viscous liquid stationary phase (often a liquid silicone-based material) and a mobile gas (most often helium). The stationary phase is adhered to the inside of a small-diameter (commonly 0.53 – 0.18mm inside diameter) glass or fused-silica tube (a capillary column) or a solid matrix inside a larger metal tube (a packed column). It is widely used in analytical chemistry; though the high temperatures used in GC make it unsuitable for high molecular weight biopolymers or proteins (heat denatures them), frequently encountered in biochemistry, it is well suited for use in the petrochemical, environmental monitoring and remediation, and industrial chemical fields. It is also used extensively in chemistry research.",
"title": "Techniques by physical state of mobile phase"
},
{
"paragraph_id": 17,
"text": "Liquid chromatography (LC) is a separation technique in which the mobile phase is a liquid. It can be carried out either in a column or a plane. Present day liquid chromatography that generally utilizes very small packing particles and a relatively high pressure is referred to as high-performance liquid chromatography.",
"title": "Techniques by physical state of mobile phase"
},
{
"paragraph_id": 18,
"text": "In HPLC the sample is forced by a liquid at high pressure (the mobile phase) through a column that is packed with a stationary phase composed of irregularly or spherically shaped particles, a porous monolithic layer, or a porous membrane. Monoliths are \"sponge-like chromatographic media\" and are made up of an unending block of organic or inorganic parts. HPLC is historically divided into two different sub-classes based on the polarity of the mobile and stationary phases. Methods in which the stationary phase is more polar than the mobile phase (e.g., toluene as the mobile phase, silica as the stationary phase) are termed normal phase liquid chromatography (NPLC) and the opposite (e.g., water-methanol mixture as the mobile phase and C18 (octadecylsilyl) as the stationary phase) is termed reversed phase liquid chromatography (RPLC).",
"title": "Techniques by physical state of mobile phase"
},
{
"paragraph_id": 19,
"text": "Supercritical fluid chromatography is a separation technique in which the mobile phase is a fluid above and relatively close to its critical temperature and pressure.",
"title": "Techniques by physical state of mobile phase"
},
{
"paragraph_id": 20,
"text": "Specific techniques under this broad heading are listed below.",
"title": "Techniques by physical state of mobile phase"
},
{
"paragraph_id": 21,
"text": "Affinity chromatography is based on selective non-covalent interaction between an analyte and specific molecules. It is very specific, but not very robust. It is often used in biochemistry in the purification of proteins bound to tags. These fusion proteins are labeled with compounds such as His-tags, biotin or antigens, which bind to the stationary phase specifically. After purification, these tags are usually removed and the pure protein is obtained.",
"title": "Affinity chromatography"
},
{
"paragraph_id": 22,
"text": "Affinity chromatography often utilizes a biomolecule's affinity for a metal (Zn, Cu, Fe, etc.). Columns are often manually prepared and could be designed specifically for the proteins of interest. Traditional affinity columns are used as a preparative step to flush out unwanted biomolecules, or as a primary step in analyzing a protein with unknown physical properties.",
"title": "Affinity chromatography"
},
{
"paragraph_id": 23,
"text": "However, liquid chromatography techniques exist that do utilize affinity chromatography properties. Immobilized metal affinity chromatography (IMAC) is useful to separate the aforementioned molecules based on the relative affinity for the metal. Often these columns can be loaded with different metals to create a column with a targeted affinity.",
"title": "Affinity chromatography"
},
{
"paragraph_id": 24,
"text": "Ion exchange chromatography (usually referred to as ion chromatography) uses an ion exchange mechanism to separate analytes based on their respective charges. It is usually performed in columns but can also be useful in planar mode. Ion exchange chromatography uses a charged stationary phase to separate charged compounds including anions, cations, amino acids, peptides, and proteins. In conventional methods the stationary phase is an ion-exchange resin that carries charged functional groups that interact with oppositely charged groups of the compound to retain. There are two types of ion exchange chromatography: Cation-Exchange and Anion-Exchange. In the Cation-Exchange Chromatography the stationary phase has negative charge and the exchangeable ion is a cation, whereas, in the Anion-Exchange Chromatography the stationary phase has positive charge and the exchangeable ion is an anion. Ion exchange chromatography is commonly used to purify proteins using FPLC.",
"title": "Techniques by separation mechanism"
},
{
"paragraph_id": 25,
"text": "Size-exclusion chromatography (SEC) is also known as gel permeation chromatography (GPC) or gel filtration chromatography and separates molecules according to their size (or more accurately according to their hydrodynamic diameter or hydrodynamic volume). Smaller molecules are able to enter the pores of the media and, therefore, molecules are trapped and removed from the flow of the mobile phase. The average residence time in the pores depends upon the effective size of the analyte molecules. However, molecules that are larger than the average pore size of the packing are excluded and thus suffer essentially no retention; such species are the first to be eluted. It is generally a low-resolution chromatography technique and thus it is often reserved for the final, \"polishing\" step of a purification. It is also useful for determining the tertiary structure and quaternary structure of purified proteins, especially since it can be carried out under native solution conditions.",
"title": "Techniques by separation mechanism"
},
{
"paragraph_id": 26,
"text": "An expanded bed chromatographic adsorption (EBA) column for a biochemical separation process comprises a pressure equalization liquid distributor having a self-cleaning function below a porous blocking sieve plate at the bottom of the expanded bed, an upper part nozzle assembly having a backflush cleaning function at the top of the expanded bed, a better distribution of the feedstock liquor added into the expanded bed ensuring that the fluid passed through the expanded bed layer displays a state of piston flow. The expanded bed layer displays a state of piston flow. The expanded bed chromatographic separation column has advantages of increasing the separation efficiency of the expanded bed.",
"title": "Techniques by separation mechanism"
},
{
"paragraph_id": 27,
"text": "Expanded-bed adsorption (EBA) chromatography is a convenient and effective technique for the capture of proteins directly from unclarified crude sample. In EBA chromatography, the settled bed is first expanded by upward flow of equilibration buffer. The crude feed, a mixture of soluble proteins, contaminants, cells, and cell debris, is then passed upward through the expanded bed. Target proteins are captured on the adsorbent, while particulates and contaminants pass through. A change to elution buffer while maintaining upward flow results in desorption of the target protein in expanded-bed mode. Alternatively, if the flow is reversed, the adsorbed particles will quickly settle and the proteins can be desorbed by an elution buffer. The mode used for elution (expanded-bed versus settled-bed) depends on the characteristics of the feed. After elution, the adsorbent is cleaned with a predefined cleaning-in-place (CIP) solution, with cleaning followed by either column regeneration (for further use) or storage.",
"title": "Techniques by separation mechanism"
},
{
"paragraph_id": 28,
"text": "Reversed-phase chromatography (RPC) is any liquid chromatography procedure in which the mobile phase is significantly more polar than the stationary phase. It is so named because in normal-phase liquid chromatography, the mobile phase is significantly less polar than the stationary phase. Hydrophobic molecules in the mobile phase tend to adsorb to the relatively hydrophobic stationary phase. Hydrophilic molecules in the mobile phase will tend to elute first. Separating columns typically comprise a C8 or C18 carbon-chain bonded to a silica particle substrate.",
"title": "Special techniques"
},
{
"paragraph_id": 29,
"text": "Hydrophobic Interaction Chromatography (HIC) is a purification and analytical technique that separates analytes, such as proteins, based on hydrophobic interactions between that analyte and the chromatographic matrix. It can provide a non-denaturing orthogonal approach to reversed phase separation, preserving native structures and potentially protein activity. In hydrophobic interaction chromatography, the matrix material is lightly substituted with hydrophobic groups. These groups can range from methyl, ethyl, propyl, butyl, octyl, or phenyl groups. At high salt concentrations, non-polar sidechains on the surface on proteins \"interact\" with the hydrophobic groups; that is, both types of groups are excluded by the polar solvent (hydrophobic effects are augmented by increased ionic strength). Thus, the sample is applied to the column in a buffer which is highly polar, which drives an association of hydrophobic patches on the analyte with the stationary phase. The eluent is typically an aqueous buffer with decreasing salt concentrations, increasing concentrations of detergent (which disrupts hydrophobic interactions), or changes in pH. Of critical importance is the type of salt used, with more kosmotropic salts as defined by the Hofmeister series providing the most water structuring around the molecule and resulting hydrophobic pressure. Ammonium sulfate is frequently used for this purpose. The addition of organic solvents or other less polar constituents may assist in improving resolution.",
"title": "Special techniques"
},
{
"paragraph_id": 30,
"text": "In general, Hydrophobic Interaction Chromatography (HIC) is advantageous if the sample is sensitive to pH change or harsh solvents typically used in other types of chromatography but not high salt concentrations. Commonly, it is the amount of salt in the buffer which is varied. In 2012, Müller and Franzreb described the effects of temperature on HIC using Bovine Serum Albumin (BSA) with four different types of hydrophobic resin. The study altered temperature as to effect the binding affinity of BSA onto the matrix. It was concluded that cycling temperature from 50 to 10 degrees would not be adequate to effectively wash all BSA from the matrix but could be very effective if the column would only be used a few times. Using temperature to effect change allows labs to cut costs on buying salt and saves money.",
"title": "Special techniques"
},
{
"paragraph_id": 31,
"text": "If high salt concentrations along with temperature fluctuations want to be avoided you can use a more hydrophobic to compete with your sample to elute it. [source] This so-called salt independent method of HIC showed a direct isolation of Human Immunoglobulin G (IgG) from serum with satisfactory yield and used Beta-cyclodextrin as a competitor to displace IgG from the matrix. This largely opens up the possibility of using HIC with samples which are salt sensitive as we know high salt concentrations precipitate proteins.",
"title": "Special techniques"
},
{
"paragraph_id": 32,
"text": "Hydrodynamic chromatography (HDC) is derived from the observed phenomenon that large droplets move faster than small ones. In a column, this happens because the center of mass of larger droplets is prevented from being as close to the sides of the column as smaller droplets because of their larger overall size. Larger droplets will elute first from the middle of the column while smaller droplets stick to the sides of the column and elute last. This form of chromatography is useful for separating analytes by molar mass, size, shape, and structure when used in conjunction with light scattering detectors, viscometers, and refractometers. The two main types of HDC are open tube and packed column. Open tube offers rapid separation times for small particles, whereas packed column HDC can increase resolution and is better suited for particles with an average molecular mass larger than 10 5 {\\displaystyle 10^{5}} daltons. HDC differs from other types of chromatography because the separation only takes place in the interstitial volume, which is the volume surrounding and in between particles in a packed column.",
"title": "Special techniques"
},
{
"paragraph_id": 33,
"text": "HDC shares the same order of elution as Size Exclusion Chromatography (SEC) but the two processes still vary in many ways. In a study comparing the two types of separation, Isenberg, Brewer, Côté, and Striegel use both methods for polysaccharide characterization and conclude that HDC coupled with multiangle light scattering (MALS) achieves more accurate molar mass distribution when compared to off-line MALS than SEC in significantly less time. This is largely due to SEC being a more destructive technique because of the pores in the column degrading the analyte during separation, which tends to impact the mass distribution. However, the main disadvantage of HDC is low resolution of analyte peaks, which makes SEC a more viable option when used with chemicals that are not easily degradable and where rapid elution is not important.",
"title": "Special techniques"
},
{
"paragraph_id": 34,
"text": "HDC plays an especially important role in the field of microfluidics. The first successful apparatus for HDC-on-a-chip system was proposed by Chmela, et al. in 2002. Their design was able to achieve separations using an 80 mm long channel on the timescale of 3 minutes for particles with diameters ranging from 26 to 110 nm, but the authors expressed a need to improve the retention and dispersion parameters. In a 2010 publication by Jellema, Markesteijn, Westerweel, and Verpoorte, implementing HDC with a recirculating bidirectional flow resulted in high resolution, size based separation with only a 3 mm long channel. Having such a short channel and high resolution was viewed as especially impressive considering that previous studies used channels that were 80 mm in length. For a biological application, in 2007, Huh, et al. proposed a microfluidic sorting device based on HDC and gravity, which was useful for preventing potentially dangerous particles with diameter larger than 6 microns from entering the bloodstream when injecting contrast agents in ultrasounds. This study also made advances for environmental sustainability in microfluidics due to the lack of outside electronics driving the flow, which came as an advantage of using a gravity based device.",
"title": "Special techniques"
},
{
"paragraph_id": 35,
"text": "In some cases, the selectivity provided by the use of one column can be insufficient to provide resolution of analytes in complex samples. Two-dimensional chromatography aims to increase the resolution of these peaks by using a second column with different physico-chemical (chemical classification) properties. Since the mechanism of retention on this new solid support is different from the first dimensional separation, it can be possible to separate compounds by two-dimensional chromatography that are indistinguishable by one-dimensional chromatography. Furthermore, the separation on the second dimension occurs faster than the first dimension. An example of a two-dimensional TLC separation is where the sample is spotted at one corner of a square plate, developed, air-dried, then rotated by 90° and usually redeveloped in a second solvent system. Two-dimensional chromatography can be applied to GC or LC separations. This separation method can also be used in a heart-cutting approach, where specific regions of interest on the first dimension are selected for separation by the second dimension, or in a comprehensive approach, where all the analytes from the first dimension undergo the second dimension separation.",
"title": "Special techniques"
},
{
"paragraph_id": 36,
"text": "The simulated moving bed (SMB) technique is a variant of high performance liquid chromatography; it is used to separate particles and/or chemical compounds that would be difficult or impossible to resolve otherwise. This increased separation is brought about by a valve-and-column arrangement that is used to lengthen the stationary phase indefinitely. In the moving bed technique of preparative chromatography the feed entry and the analyte recovery are simultaneous and continuous, but because of practical difficulties with a continuously moving bed, simulated moving bed technique was proposed. In the simulated moving bed technique instead of moving the bed, the sample inlet and the analyte exit positions are moved continuously, giving the impression of a moving bed. True moving bed chromatography (TMBC) is only a theoretical concept. Its simulation, SMBC is achieved by the use of a multiplicity of columns in series and a complex valve arrangement, which provides for sample and solvent feed, and also analyte and waste takeoff at appropriate locations of any column, whereby it allows switching at regular intervals the sample entry in one direction, the solvent entry in the opposite direction, whilst changing the analyte and waste takeoff positions appropriately as well.",
"title": "Special techniques"
},
{
"paragraph_id": 37,
"text": "Pyrolysis–gas chromatography–mass spectrometry is a method of chemical analysis in which the sample is heated to decomposition to produce smaller molecules that are separated by gas chromatography and detected using mass spectrometry.",
"title": "Special techniques"
},
{
"paragraph_id": 38,
"text": "Pyrolysis is the thermal decomposition of materials in an inert atmosphere or a vacuum. The sample is put into direct contact with a platinum wire, or placed in a quartz sample tube, and rapidly heated to 600–1000 °C. Depending on the application even higher temperatures are used. Three different heating techniques are used in actual pyrolyzers: Isothermal furnace, inductive heating (Curie Point filament), and resistive heating using platinum filaments. Large molecules cleave at their weakest points and produce smaller, more volatile fragments. These fragments can be separated by gas chromatography. Pyrolysis GC chromatograms are typically complex because a wide range of different decomposition products is formed. The data can either be used as fingerprints to prove material identity or the GC/MS data is used to identify individual fragments to obtain structural information. To increase the volatility of polar fragments, various methylating reagents can be added to a sample before pyrolysis.",
"title": "Special techniques"
},
{
"paragraph_id": 39,
"text": "Besides the usage of dedicated pyrolyzers, pyrolysis GC of solid and liquid samples can be performed directly inside Programmable Temperature Vaporizer (PTV) injectors that provide quick heating (up to 30 °C/s) and high maximum temperatures of 600–650 °C. This is sufficient for some pyrolysis applications. The main advantage is that no dedicated instrument has to be purchased and pyrolysis can be performed as part of routine GC analysis. In this case, quartz GC inlet liners have to be used. Quantitative data can be acquired, and good results of derivatization inside the PTV injector are published as well.",
"title": "Special techniques"
},
{
"paragraph_id": 40,
"text": "Fast protein liquid chromatography (FPLC), is a form of liquid chromatography that is often used to analyze or purify mixtures of proteins. As in other forms of chromatography, separation is possible because the different components of a mixture have different affinities for two materials, a moving fluid (the \"mobile phase\") and a porous solid (the stationary phase). In FPLC the mobile phase is an aqueous solution, or \"buffer\". The buffer flow rate is controlled by a positive-displacement pump and is normally kept constant, while the composition of the buffer can be varied by drawing fluids in different proportions from two or more external reservoirs. The stationary phase is a resin composed of beads, usually of cross-linked agarose, packed into a cylindrical glass or plastic column. FPLC resins are available in a wide range of bead sizes and surface ligands depending on the application.",
"title": "Special techniques"
},
{
"paragraph_id": 41,
"text": "Countercurrent chromatography (CCC) is a type of liquid-liquid chromatography, where both the stationary and mobile phases are liquids and the liquid stationary phase is held stagnant by a strong centrifugal force.",
"title": "Special techniques"
},
{
"paragraph_id": 42,
"text": "The operating principle of CCC instrument requires a column consisting of an open tube coiled around a bobbin. The bobbin is rotated in a double-axis gyratory motion (a cardioid), which causes a variable gravity (G) field to act on the column during each rotation. This motion causes the column to see one partitioning step per revolution and components of the sample separate in the column due to their partitioning coefficient between the two immiscible liquid phases used. There are many types of CCC available today. These include HSCCC (High Speed CCC) and HPCCC (High Performance CCC). HPCCC is the latest and best-performing version of the instrumentation available currently.",
"title": "Special techniques"
},
{
"paragraph_id": 43,
"text": "In the CPC (centrifugal partition chromatography or hydrostatic countercurrent chromatography) instrument, the column consists of a series of cells interconnected by ducts attached to a rotor. This rotor rotates on its central axis creating the centrifugal field necessary to hold the stationary phase in place. The separation process in CPC is governed solely by the partitioning of solutes between the stationary and mobile phases, which mechanism can be easily described using the partition coefficients (KD) of solutes. CPC instruments are commercially available for laboratory, pilot, and industrial-scale separations with different sizes of columns ranging from some 10 milliliters to 10 liters volume.",
"title": "Special techniques"
},
{
"paragraph_id": 44,
"text": "In contrast to Counter current chromatography (see above), periodic counter-current chromatography (PCC) uses a solid stationary phase and only a liquid mobile phase. It thus is much more similar to conventional affinity chromatography than to counter current chromatography. PCC uses multiple columns, which during the loading phase are connected in line. This mode allows for overloading the first column in this series without losing product, which already breaks through the column before the resin is fully saturated. The breakthrough product is captured on the subsequent column(s). In a next step the columns are disconnected from one another. The first column is washed and eluted, while the other column(s) are still being loaded. Once the (initially) first column is re-equilibrated, it is re-introduced to the loading stream, but as last column. The process then continues in a cyclic fashion.",
"title": "Special techniques"
},
{
"paragraph_id": 45,
"text": "Chiral chromatography involves the separation of stereoisomers. In the case of enantiomers, these have no chemical or physical differences apart from being three-dimensional mirror images. To enable chiral separations to take place, either the mobile phase or the stationary phase must themselves be made chiral, giving differing affinities between the analytes. Chiral chromatography HPLC columns (with a chiral stationary phase) in both normal and reversed phase are commercially available.",
"title": "Special techniques"
},
{
"paragraph_id": 46,
"text": "Conventional chromatography are incapable of separating racemic mixtures of enantiomers. However, in some cases nonracemic mixtures of enantiomers may be separated unexpectedly by conventional liquid chromatography (e. g. HPLC without chiral mobile phase or stationary phase ).",
"title": "Special techniques"
},
{
"paragraph_id": 47,
"text": "Aqueous normal-phase (ANP) chromatography is characterized by the elution behavior of classical normal phase mode (i.e. where the mobile phase is significantly less polar than the stationary phase) in which water is one of the mobile phase solvent system components. It is distinguished from hydrophilic interaction liquid chromatography (HILIC) in that the retention mechanism is due to adsorption rather than partitioning.",
"title": "Special techniques"
},
{
"paragraph_id": 48,
"text": "Chromatography is used in many fields including the pharmaceutical industry, the food and beverage industry, the chemical industry, forensic science, environment analysis, and hospitals.",
"title": "Applications"
}
] | In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent called the mobile phase, which carries it through a system on which a material called the stationary phase is fixed. Because the different constituents of the mixture tend to have different affinities for the stationary phase and are retained for different lengths of time depending on their interactions with its surface sites, the constituents travel at different apparent velocities in the mobile fluid, causing them to separate. The separation is based on the differential partitioning between the mobile and the stationary phases. Subtle differences in a compound's partition coefficient result in differential retention on the stationary phase and thus affect the separation. Chromatography may be preparative or analytical. The purpose of preparative chromatography is to separate the components of a mixture for later use, and is thus a form of purification. This process is associated with higher costs due to its mode of production. Analytical chromatography is done normally with smaller amounts of material and is for establishing the presence or measuring the relative proportions of analytes in a mixture. The two types are not mutually exclusive. | 2001-09-13T22:58:21Z | 2023-12-26T16:59:19Z | [
"Template:Cite book",
"Template:Cite journal",
"Template:Commons category",
"Template:Analytical chemistry",
"Template:Continuum mechanics",
"Template:Chem name",
"Template:Further",
"Template:Div col",
"Template:Reflist",
"Template:Citation",
"Template:TopicTOC-Chemistry",
"Template:Details",
"Template:Cite OEtymD",
"Template:Wikibooks",
"Template:Pathology",
"Template:Short description",
"Template:Main",
"Template:Branches of chemistry",
"Template:Paragraph break",
"Template:Webarchive",
"Template:Chromatography",
"Template:IPAc-en",
"Template:Use dmy dates",
"Template:Doi",
"Template:Separation processes",
"Template:For",
"Template:Cite web",
"Template:Authority control",
"Template:Div col end"
] | https://en.wikipedia.org/wiki/Chromatography |
6,330 | Clement Martyn Doke | Clement Martyn Doke (16 May 1893 in Bristol, United Kingdom – 24 February 1980 in East London, South Africa) was a South African linguist working mainly on African languages. Realizing that the grammatical structures of Bantu languages are quite different from those of European languages, he was one of the first African linguists of his time to abandon the Euro-centric approach to language description for a more locally grounded one. A most prolific writer, he published a string of grammars, several dictionaries, comparative work, and a history of Bantu linguistics.
The Doke family had been engaged in missionary activity for the Baptist Church for some generations. His father, Reverend Joseph J. Doke, left England and travelled to South Africa in 1882, where he met and married Agnes Biggs. They returned to England, where Clement was born as the third of four children. The family moved to New Zealand and eventually returned to South Africa in 1903, where it later settled in Johannesburg.
At the age of 18, Clement received a bachelor's degree from Transvaal University College in Pretoria (now the University of Pretoria). He decided to devote his life to missionary activity. In 1913, he accompanied his father on a tour of north-western Rhodesia, to an area called Lambaland, now known as Ilamba. It is at the watershed of the Congo and Zambesi rivers. Part of the district lay in Northern Rhodesia and part of the Belgian Congo. The Cape-Cairo Railway threaded through its eastern portion; otherwise, most travel had to be on foot.
The Reverend William Arthur Phillips of the Nyasa Industrial Mission in Blantyre had established a Baptist mission there in 1905; it served an area of 25,000 square miles (65,000 km) and 50,000 souls. The Dokes were supposed to investigate whether the mission in Lambaland could be taken over by the Baptist Union of South Africa. It was on that trip that Doke's father contracted enteric fever and died soon afterwards. Mahatma Gandhi attended the memorial service and addressed the congregation. Clement assumed his father's role.
The South African Baptists decided to take over Kafulafuta Mission, and its founder, Reverend Phillips, remained as superintendent. Clement Doke returned to Kafulafuta as missionary in 1914, followed by his sister Olive two years later.
At first, Clement Doke was frustrated by his inability to communicate with the Lamba. The only written material available at the time was a translation of Jonah and a collection of 47 hymns. Soon, however, he mastered the language and published his first book, Ifintu Fyakwe Lesa ("The Things of God, a Primer of Scripture Knowledge") in 1917. He enrolled in Johannesburg as the extension of Transvaal University College for an MA degree. His thesis was published as The Grammar of the Lamba language. The book is couched in traditional grammatical terms, as Doke had not yet established his innovative method to analyse and describe the Bantu languages. His later Textbook of Lamba Grammar is far superior in that respect.
Doke was also interested in ethnology. In 1931 he compiled The Lambas of Northern Rhodesia, which remains one of the outstanding ethnographic descriptions of the peoples of Central Africa. For Doke, literacy was part of evangelisation since it was required so that people to appreciate the Bible's message, but it was only after his retirement that he completed the translation of the Bible into Lamba. It was published under the title of Amasiwi AwaLesa ("The Words of God") in 1959.
In 1919, Doke married Hilda Lehmann, who accompanied him back to Lambaland. Both contracted malaria during their work, and she was forbidden to return to Lambaland. Clement Doke also realised that his field work could not continue much longer, and he left in 1921. He was recruited by the newly-founded University of the Witwatersrand. So that he could secure a qualification as a lecturer, the family moved to England, where he registered at the School of Oriental and African Studies. His major languages were Lamba and Luba, but as no suitable examiner was available, he eventually had to change his language to Zulu.
Doke took up his appointment in the new Department of Bantu Studies at the University of Witwatersrand in 1923. In 1925 he received his D. Litt. for his doctoral thesis The Phonetics of the Zulu Language and was promoted to Senior Lecturer. In 1931 he was appointed to the Chair of Bantu Studies and thus headed the Department of Bantu Studies. The Department acted as a catalyst for the admission of Africans to the university. As early as 1925 a limited number were admitted to the vacation course in African Studies. Doke supported the appointment of Benedict Wallet Vilakazi as member of the staff, as he believed a native speaker was essential for acquiring a language. That provoked a storm of criticism and controversy from the public. Both of them collaborated on the Zulu-English Dictionary. First published in 1948, it is still one of the best examples of lexicography for any Bantu language.
At the request of the government of Southern Rhodesia, Doke investigated the range of dialect diversity among the languages of the country and made recommendations for Unified Shona, which formed the basis for Standard Shona. He devised a unified orthography based on the Zezuru, Karanga and Manyika dialects. However, Doke's orthography was never fully accepted, and the South African government introduced an alternative, which left Shona with two competing orthographies between 1935 and 1955.
During his tenure, Doke developed and promoted a method of linguistic analysis and description of the Bantu languages that was based upon the structure of these languages. The "Dokean model" continues to be one of the dominant models of linguistic description in Southern and Central Africa. His classification of the Bantu languages was for many years the dominant view of the interrelations among the African languages. He was also an early describer of Khoisan and Bantu click consonants, devising phonetic symbols for a number of them.
Doke served the University of the Witwatersrand until his retirement in 1953. He was awarded the honorary degree of Doctor of Letters by Rhodes University and the honorary degree of Doctor of Laws by the University of the Witwatersrand in 1972.
The former missionary always remained devoted to the Baptist Church. He was elected President of the South African Baptist Union in 1949 and spent a year visiting churches and mission stations. He used his presidential address in condemning the recently established apartheid policy: I solemnly warn the Government that the spirit behind their apartheid legislation, and the way in which they are introducing discriminatory measures of all types today, will bring disaster upon this fair land of ours. | [
{
"paragraph_id": 0,
"text": "Clement Martyn Doke (16 May 1893 in Bristol, United Kingdom – 24 February 1980 in East London, South Africa) was a South African linguist working mainly on African languages. Realizing that the grammatical structures of Bantu languages are quite different from those of European languages, he was one of the first African linguists of his time to abandon the Euro-centric approach to language description for a more locally grounded one. A most prolific writer, he published a string of grammars, several dictionaries, comparative work, and a history of Bantu linguistics.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The Doke family had been engaged in missionary activity for the Baptist Church for some generations. His father, Reverend Joseph J. Doke, left England and travelled to South Africa in 1882, where he met and married Agnes Biggs. They returned to England, where Clement was born as the third of four children. The family moved to New Zealand and eventually returned to South Africa in 1903, where it later settled in Johannesburg.",
"title": "Early life and career"
},
{
"paragraph_id": 2,
"text": "At the age of 18, Clement received a bachelor's degree from Transvaal University College in Pretoria (now the University of Pretoria). He decided to devote his life to missionary activity. In 1913, he accompanied his father on a tour of north-western Rhodesia, to an area called Lambaland, now known as Ilamba. It is at the watershed of the Congo and Zambesi rivers. Part of the district lay in Northern Rhodesia and part of the Belgian Congo. The Cape-Cairo Railway threaded through its eastern portion; otherwise, most travel had to be on foot.",
"title": "Early life and career"
},
{
"paragraph_id": 3,
"text": "The Reverend William Arthur Phillips of the Nyasa Industrial Mission in Blantyre had established a Baptist mission there in 1905; it served an area of 25,000 square miles (65,000 km) and 50,000 souls. The Dokes were supposed to investigate whether the mission in Lambaland could be taken over by the Baptist Union of South Africa. It was on that trip that Doke's father contracted enteric fever and died soon afterwards. Mahatma Gandhi attended the memorial service and addressed the congregation. Clement assumed his father's role.",
"title": "Early life and career"
},
{
"paragraph_id": 4,
"text": "The South African Baptists decided to take over Kafulafuta Mission, and its founder, Reverend Phillips, remained as superintendent. Clement Doke returned to Kafulafuta as missionary in 1914, followed by his sister Olive two years later.",
"title": "Early life and career"
},
{
"paragraph_id": 5,
"text": "At first, Clement Doke was frustrated by his inability to communicate with the Lamba. The only written material available at the time was a translation of Jonah and a collection of 47 hymns. Soon, however, he mastered the language and published his first book, Ifintu Fyakwe Lesa (\"The Things of God, a Primer of Scripture Knowledge\") in 1917. He enrolled in Johannesburg as the extension of Transvaal University College for an MA degree. His thesis was published as The Grammar of the Lamba language. The book is couched in traditional grammatical terms, as Doke had not yet established his innovative method to analyse and describe the Bantu languages. His later Textbook of Lamba Grammar is far superior in that respect.",
"title": "Study of Lamba"
},
{
"paragraph_id": 6,
"text": "Doke was also interested in ethnology. In 1931 he compiled The Lambas of Northern Rhodesia, which remains one of the outstanding ethnographic descriptions of the peoples of Central Africa. For Doke, literacy was part of evangelisation since it was required so that people to appreciate the Bible's message, but it was only after his retirement that he completed the translation of the Bible into Lamba. It was published under the title of Amasiwi AwaLesa (\"The Words of God\") in 1959.",
"title": "Study of Lamba"
},
{
"paragraph_id": 7,
"text": "In 1919, Doke married Hilda Lehmann, who accompanied him back to Lambaland. Both contracted malaria during their work, and she was forbidden to return to Lambaland. Clement Doke also realised that his field work could not continue much longer, and he left in 1921. He was recruited by the newly-founded University of the Witwatersrand. So that he could secure a qualification as a lecturer, the family moved to England, where he registered at the School of Oriental and African Studies. His major languages were Lamba and Luba, but as no suitable examiner was available, he eventually had to change his language to Zulu.",
"title": "University of the Witwatersrand"
},
{
"paragraph_id": 8,
"text": "Doke took up his appointment in the new Department of Bantu Studies at the University of Witwatersrand in 1923. In 1925 he received his D. Litt. for his doctoral thesis The Phonetics of the Zulu Language and was promoted to Senior Lecturer. In 1931 he was appointed to the Chair of Bantu Studies and thus headed the Department of Bantu Studies. The Department acted as a catalyst for the admission of Africans to the university. As early as 1925 a limited number were admitted to the vacation course in African Studies. Doke supported the appointment of Benedict Wallet Vilakazi as member of the staff, as he believed a native speaker was essential for acquiring a language. That provoked a storm of criticism and controversy from the public. Both of them collaborated on the Zulu-English Dictionary. First published in 1948, it is still one of the best examples of lexicography for any Bantu language.",
"title": "University of the Witwatersrand"
},
{
"paragraph_id": 9,
"text": "At the request of the government of Southern Rhodesia, Doke investigated the range of dialect diversity among the languages of the country and made recommendations for Unified Shona, which formed the basis for Standard Shona. He devised a unified orthography based on the Zezuru, Karanga and Manyika dialects. However, Doke's orthography was never fully accepted, and the South African government introduced an alternative, which left Shona with two competing orthographies between 1935 and 1955.",
"title": "University of the Witwatersrand"
},
{
"paragraph_id": 10,
"text": "During his tenure, Doke developed and promoted a method of linguistic analysis and description of the Bantu languages that was based upon the structure of these languages. The \"Dokean model\" continues to be one of the dominant models of linguistic description in Southern and Central Africa. His classification of the Bantu languages was for many years the dominant view of the interrelations among the African languages. He was also an early describer of Khoisan and Bantu click consonants, devising phonetic symbols for a number of them.",
"title": "University of the Witwatersrand"
},
{
"paragraph_id": 11,
"text": "Doke served the University of the Witwatersrand until his retirement in 1953. He was awarded the honorary degree of Doctor of Letters by Rhodes University and the honorary degree of Doctor of Laws by the University of the Witwatersrand in 1972.",
"title": "University of the Witwatersrand"
},
{
"paragraph_id": 12,
"text": "The former missionary always remained devoted to the Baptist Church. He was elected President of the South African Baptist Union in 1949 and spent a year visiting churches and mission stations. He used his presidential address in condemning the recently established apartheid policy: I solemnly warn the Government that the spirit behind their apartheid legislation, and the way in which they are introducing discriminatory measures of all types today, will bring disaster upon this fair land of ours.",
"title": "University of the Witwatersrand"
}
] | Clement Martyn Doke was a South African linguist working mainly on African languages. Realizing that the grammatical structures of Bantu languages are quite different from those of European languages, he was one of the first African linguists of his time to abandon the Euro-centric approach to language description for a more locally grounded one. A most prolific writer, he published a string of grammars, several dictionaries, comparative work, and a history of Bantu linguistics. | 2001-09-13T17:30:56Z | 2023-11-15T06:24:56Z | [
"Template:Convert",
"Template:Authority control",
"Template:Short description",
"Template:More citations needed",
"Template:Infobox scientist",
"Template:Cite web",
"Template:Use dmy dates",
"Template:Use South African English",
"Template:Reflist"
] | https://en.wikipedia.org/wiki/Clement_Martyn_Doke |
6,331 | Carl Meinhof | Carl Friedrich Michael Meinhof (23 July 1857 – 11 February 1944) was a German linguist and one of the first linguists to study African languages.
Meinhof was born in Barzwitz near Rügenwalde in the Province of Pomerania, Kingdom of Prussia. He studied at the University of Tübingen and at the University of Greifswald. In 1905 he became professor at the School of Oriental Studies in Berlin. On 5 May 1933 he became a member of the Nazi Party.
His most notable work was developing comparative grammar studies of the Bantu languages, building on the pioneering work of Wilhelm Bleek. In his work, Meinhof looked at the common Bantu languages such as Swahili and Zulu to determine similarities and differences.
In his work, Meinhof looked at noun classes with all Bantu languages having at least 10 classes and with 22 classes of nouns existing throughout the Bantu languages, though his definition of noun class differs slightly from the accepted one, considering the plural form of a word as belonging to a different class from the singular form (thus leading, for example, to consider a language like French as having four classes instead of two). While no language has all 22 (later: 23) classes active, Venda has 20, Lozi has 18, and Ganda has 16 or 17 (depending on whether the locative class 23 e- is included). All Bantu languages have a noun class specifically for humans (sometimes including other animate beings).
Meinhof also examined other African languages, including groups classified at the time as Kordofanian, Bushman, Khoikhoi, and Hamitic.
Meinhof developed a comprehensive classification scheme for African languages. His classification was the standard one for many years (Greenberg 1955:3). It was replaced by those of Joseph Greenberg in 1955 and in 1963.
In 1902, Meinhof made recordings of East African music. These are among the first recordings made of traditional African music.
In 1912, Carl Meinhof published Die Sprachen der Hamiten (The Languages of the Hamites). He used the term Hamitic. Meinhof's system of classification of the Hamitic languages was based on a belief that "speakers of Hamitic became largely coterminous with cattle herding peoples with essentially Caucasian origins, intrinsically different from and superior to the 'Negroes of Africa'." However, in the case of the so-called Nilo-Hamitic languages (a concept he introduced), it was based on the typological feature of gender and a "fallacious theory of language mixture." Meinhof did this in spite of earlier work by scholars such as Lepsius and Johnston demonstrating that the languages which he would later dub "Nilo-Hamitic" were in fact Nilotic languages with numerous similarities in vocabulary with other Nilotic languages.
Carl Meinhof was the great-uncle (the brother of the grandfather) of Ulrike Meinhof, a founding member of the German Red Army Faction (RAF), a left-wing militant group, which operated in West Germany in the 1970s and 1980s. | [
{
"paragraph_id": 0,
"text": "Carl Friedrich Michael Meinhof (23 July 1857 – 11 February 1944) was a German linguist and one of the first linguists to study African languages.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Meinhof was born in Barzwitz near Rügenwalde in the Province of Pomerania, Kingdom of Prussia. He studied at the University of Tübingen and at the University of Greifswald. In 1905 he became professor at the School of Oriental Studies in Berlin. On 5 May 1933 he became a member of the Nazi Party.",
"title": "Early years and career"
},
{
"paragraph_id": 2,
"text": "His most notable work was developing comparative grammar studies of the Bantu languages, building on the pioneering work of Wilhelm Bleek. In his work, Meinhof looked at the common Bantu languages such as Swahili and Zulu to determine similarities and differences.",
"title": "Works"
},
{
"paragraph_id": 3,
"text": "In his work, Meinhof looked at noun classes with all Bantu languages having at least 10 classes and with 22 classes of nouns existing throughout the Bantu languages, though his definition of noun class differs slightly from the accepted one, considering the plural form of a word as belonging to a different class from the singular form (thus leading, for example, to consider a language like French as having four classes instead of two). While no language has all 22 (later: 23) classes active, Venda has 20, Lozi has 18, and Ganda has 16 or 17 (depending on whether the locative class 23 e- is included). All Bantu languages have a noun class specifically for humans (sometimes including other animate beings).",
"title": "Works"
},
{
"paragraph_id": 4,
"text": "Meinhof also examined other African languages, including groups classified at the time as Kordofanian, Bushman, Khoikhoi, and Hamitic.",
"title": "Works"
},
{
"paragraph_id": 5,
"text": "Meinhof developed a comprehensive classification scheme for African languages. His classification was the standard one for many years (Greenberg 1955:3). It was replaced by those of Joseph Greenberg in 1955 and in 1963.",
"title": "Works"
},
{
"paragraph_id": 6,
"text": "In 1902, Meinhof made recordings of East African music. These are among the first recordings made of traditional African music.",
"title": "Works"
},
{
"paragraph_id": 7,
"text": "In 1912, Carl Meinhof published Die Sprachen der Hamiten (The Languages of the Hamites). He used the term Hamitic. Meinhof's system of classification of the Hamitic languages was based on a belief that \"speakers of Hamitic became largely coterminous with cattle herding peoples with essentially Caucasian origins, intrinsically different from and superior to the 'Negroes of Africa'.\" However, in the case of the so-called Nilo-Hamitic languages (a concept he introduced), it was based on the typological feature of gender and a \"fallacious theory of language mixture.\" Meinhof did this in spite of earlier work by scholars such as Lepsius and Johnston demonstrating that the languages which he would later dub \"Nilo-Hamitic\" were in fact Nilotic languages with numerous similarities in vocabulary with other Nilotic languages.",
"title": "Controversial views"
},
{
"paragraph_id": 8,
"text": "Carl Meinhof was the great-uncle (the brother of the grandfather) of Ulrike Meinhof, a founding member of the German Red Army Faction (RAF), a left-wing militant group, which operated in West Germany in the 1970s and 1980s.",
"title": "Family"
}
] | Carl Friedrich Michael Meinhof was a German linguist and one of the first linguists to study African languages. | 2002-02-25T15:51:15Z | 2023-08-06T18:03:58Z | [
"Template:Infobox person",
"Template:Citation needed",
"Template:Reflist",
"Template:PM20",
"Template:Authority control",
"Template:Short description"
] | https://en.wikipedia.org/wiki/Carl_Meinhof |
6,335 | Cucurbitaceae | The Cucurbitaceae (/kjuːˌkɜːrbɪˈteɪsiːˌiː/), also called cucurbits or the gourd family, are a plant family consisting of about 965 species in around 95 genera. Those most important to humans are the following:
The plants in this family are grown around the tropics and in temperate areas, where those with edible fruits were among the earliest cultivated plants in both the Old and New Worlds. The family Cucurbitaceae ranks among the highest of plant families for number and percentage of species used as human food. The name Cucurbitaceae comes to international scientific vocabulary from Neo-Latin, from Cucurbita, the type genus, + -aceae, a standardized suffix for plant family names in modern taxonomy. The genus name comes from the Classical Latin word cucurbita, meaning "gourd".
Most of the plants in this family are annual vines, but some are woody lianas, thorny shrubs, or trees (Dendrosicyos). Many species have large, yellow or white flowers. The stems are hairy and pentangular. Tendrils are present at 90° to the leaf petioles at nodes. Leaves are exstipulate, alternate, simple palmately lobed or palmately compound. The flowers are unisexual, with male and female flowers on different plants (dioecious) or on the same plant (monoecious). The female flowers have inferior ovaries. The fruit is often a kind of modified berry called a pepo.
One of the oldest fossil cucurbits so far is †Cucurbitaciphyllum lobatum from the Paleocene epoch, found at Shirley Canal, Montana. It was described for the first time in 1924 by the paleobotanist Frank Hall Knowlton. The fossil leaf is palmate, trilobed with rounded lobal sinuses and an entire or serrate margin. It has a leaf pattern similar to the members of the genera Kedrostis, Melothria and Zehneria.
The most recent classification of Cucurbitaceae delineates 15 tribes:
Modern molecular phylogenetics suggest the following relationships:
Sweet potato whitefly is the vector of a number of cucurbit viruses that cause yellowing symptoms throughout the southern United States. | [
{
"paragraph_id": 0,
"text": "The Cucurbitaceae (/kjuːˌkɜːrbɪˈteɪsiːˌiː/), also called cucurbits or the gourd family, are a plant family consisting of about 965 species in around 95 genera. Those most important to humans are the following:",
"title": ""
},
{
"paragraph_id": 1,
"text": "The plants in this family are grown around the tropics and in temperate areas, where those with edible fruits were among the earliest cultivated plants in both the Old and New Worlds. The family Cucurbitaceae ranks among the highest of plant families for number and percentage of species used as human food. The name Cucurbitaceae comes to international scientific vocabulary from Neo-Latin, from Cucurbita, the type genus, + -aceae, a standardized suffix for plant family names in modern taxonomy. The genus name comes from the Classical Latin word cucurbita, meaning \"gourd\".",
"title": ""
},
{
"paragraph_id": 2,
"text": "Most of the plants in this family are annual vines, but some are woody lianas, thorny shrubs, or trees (Dendrosicyos). Many species have large, yellow or white flowers. The stems are hairy and pentangular. Tendrils are present at 90° to the leaf petioles at nodes. Leaves are exstipulate, alternate, simple palmately lobed or palmately compound. The flowers are unisexual, with male and female flowers on different plants (dioecious) or on the same plant (monoecious). The female flowers have inferior ovaries. The fruit is often a kind of modified berry called a pepo.",
"title": "Description"
},
{
"paragraph_id": 3,
"text": "One of the oldest fossil cucurbits so far is †Cucurbitaciphyllum lobatum from the Paleocene epoch, found at Shirley Canal, Montana. It was described for the first time in 1924 by the paleobotanist Frank Hall Knowlton. The fossil leaf is palmate, trilobed with rounded lobal sinuses and an entire or serrate margin. It has a leaf pattern similar to the members of the genera Kedrostis, Melothria and Zehneria.",
"title": "Fossil history"
},
{
"paragraph_id": 4,
"text": "The most recent classification of Cucurbitaceae delineates 15 tribes:",
"title": "Classification"
},
{
"paragraph_id": 5,
"text": "Modern molecular phylogenetics suggest the following relationships:",
"title": "Classification"
},
{
"paragraph_id": 6,
"text": "",
"title": "Classification"
},
{
"paragraph_id": 7,
"text": "Sweet potato whitefly is the vector of a number of cucurbit viruses that cause yellowing symptoms throughout the southern United States.",
"title": "Pests and diseases"
}
] | The Cucurbitaceae, also called cucurbits or the gourd family, are a plant family consisting of about 965 species in around 95 genera. Those most important to humans are the following: Cucurbita – squash, pumpkin, zucchini or courgette, some gourds
Lagenaria – calabash, and others that are inedible
Citrullus – watermelon and others
Cucumis – cucumber, various melons and vines
Momordica – bitter melon
Luffa – the common name is also luffa, sometimes spelled loofah
Cyclanthera – Caigua The plants in this family are grown around the tropics and in temperate areas, where those with edible fruits were among the earliest cultivated plants in both the Old and New Worlds. The family Cucurbitaceae ranks among the highest of plant families for number and percentage of species used as human food. The name Cucurbitaceae comes to international scientific vocabulary from Neo-Latin, from Cucurbita, the type genus, + -aceae, a standardized suffix for plant family names in modern taxonomy. The genus name comes from the Classical Latin word cucurbita, meaning "gourd". | 2002-02-25T15:43:11Z | 2023-12-28T23:13:11Z | [
"Template:Cn",
"Template:Div col end",
"Template:Clade",
"Template:Cite encyclopedia",
"Template:Short description",
"Template:Automatic taxobox",
"Template:Cite thesis",
"Template:Cite book",
"Template:Angiosperm families",
"Template:Taxonbar",
"Template:Wikt-lang",
"Template:Div col",
"Template:Cite Merriam-Webster",
"Template:Cite journal",
"Template:Cite web",
"Template:IPAc-en",
"Template:Anchor",
"Template:Reflist",
"Template:Authority control"
] | https://en.wikipedia.org/wiki/Cucurbitaceae |
6,336 | Chorded keyboard | A keyset or chorded keyboard (also called a chorded keyset, chord keyboard or chording keyboard) is a computer input device that allows the user to enter characters or commands formed by pressing several keys together, like playing a "chord" on a piano. The large number of combinations available from a small number of keys allows text or commands to be entered with one hand, leaving the other hand free. A secondary advantage is that it can be built into a device (such as a pocket-sized computer or a bicycle handlebar) that is too small to contain a normal-sized keyboard.
A chorded keyboard minus the board, typically designed to be used while held in the hand, is called a keyer. Douglas Engelbart introduced the chorded keyset as a computer interface in 1968 at what is often called "The Mother of All Demos".
Each key is mapped to a number and then can be mapped to a corresponding letter or command. By pressing two or more keys together the user can generate many combinations. In Engelbart's original mapping, he used five keys: 1, 2, 4, 8, 16. The keys were mapped as follows: a = 1, b = 2, c = 3, d = 4, and so on. If the user pressed keys 1 and 2 simultaneously, and then released the keys, 1 and 2 would be added to 3, and since C is the 3rd letter of the alphabet, and the letter "c" appeared. Unlike pressing a chord on a piano, the chord is recognized only after all the keys or mouse buttons are released. Since Engelbart introduced the keyset, several different designs have been developed based on similar concepts.
As a crude example, each finger might control one key which corresponds to one bit in a byte, so that using seven keys and seven fingers, one could enter any character in the ASCII set—if the user could remember the binary codes. Due to the small number of keys required, chording is easily adapted from a desktop to mobile environment.
Practical devices generally use simpler chords for common characters (e.g., Baudot), or may have ways to make it easier to remember the chords (e.g., Microwriter), but the same principles apply. These portable devices first became popular with the wearable computer movement in the 1980s.
Thad Starner from Georgia Institute of Technology and others published numerous studies showing that two-handed chorded text entry was faster and yielded fewer errors than on a QWERTY keyboard. Currently stenotype machines hold the record for fastest word entry. Many stenotype users can reach 300 words per minute. However, stenographers typically train for three years before reaching professional levels of speed and accuracy.
The earliest known chord keyboard was part of the "five-needle" telegraph operator station, designed by Wheatstone and Cooke in 1836, in which any two of the five needles could point left or right to indicate letters on a grid. It was designed to be used by untrained operators (who would determine which keys to press by looking at the grid), and was not used where trained telegraph operators were available.
The first widespread use of a chord keyboard was in the stenotype machine used by court reporters, which was invented in 1868 and is still in use. The output of the stenotype was originally a phonetic code that had to be transcribed later (usually by the same operator who produced the original output), rather than arbitrary text—automatic conversion software is now commonplace.
In 1874, the five-bit Baudot telegraph code and a matching 5-key chord keyboard was designed to be used with the operator forming the codes manually. The code is optimized for speed and low wear: chords were chosen so that the most common characters used the simplest chords. But telegraph operators were already using typewriters with QWERTY keyboards to "copy" received messages, and at the time it made more sense to build a typewriter that could generate the codes automatically, rather than making them learn to use a new input device.
Some early keypunch machines used a keyboard with 12 labeled keys to punch the correct holes in paper cards. The numbers 0 through 9 were represented by one punch; 26 letters were represented by combinations of two punches, and symbols were represented by combinations of two or three punches.
Braille (a writing system for the blind) uses either 6 or 8 tactile 'points' from which all letters and numbers are formed. When Louis Braille invented it, it was produced with a needle holing successively all needed points in a cardboard sheet. In 1892, Frank Haven Hall, superintendent of the Illinois Institute for the Education of the Blind, created the Hall Braille Writer, which was like a typewriter with 6 keys, one for each dot in a braille cell. The Perkins Brailler, first manufactured in 1951, uses a 6-key chord keyboard (plus a spacebar) to produce braille output, and has been very successful as a mass market affordable product. Braille, like Baudot, uses a number symbol and a shift symbol, which may be repeated for shift lock, to fit numbers and upper case into the 63 codes that 6 bits offer.
After World War II, with the arrival of electronics for reading chords and looking in tables of "codes", the postal sorting offices started to research chordic solutions to be able to employ people other than trained and expensive typists. In 1954, an important concept was discovered: chordic production is easier to master when the production is done at the release of the keys instead of when they are pressed.
Researchers at IBM investigated chord keyboards for both typewriters and computer data entry as early as 1959, with the idea that it might be faster than touch-typing if some chords were used to enter whole words or parts of words. A 1975 design by IBM Fellow Nat Rochester had 14 keys that were dimpled on the edges as well as the top, so one finger could press two adjacent keys for additional combinations. Their results were inconclusive, but research continued until at least 1978.
Doug Engelbart began experimenting with keysets to use with the mouse in the mid 1960s. In a famous 1968 demonstration, Engelbart introduced a computer human interface that included the QWERTY keyboard, a three button mouse, and a five key keyset. Engelbart used the keyset with his left hand and the mouse with his right to type text and enter commands. The mouse buttons marked selections and confirmed or aborted commands.
Users in Engelbart's Augmentation Research Center at SRI became proficient with the mouse and keyset. In the 1970s the funding Engelbart's group received from the Advanced Research Projects Agency (ARPA) was cut and many key members of Engelbart's team went to work for Xerox PARC where they continued to experiment with the mouse and keyset. Keychord sets were used at Xerox PARC in the early 1980s, along with mice, GUIs, on the Xerox Star and Alto workstations. A one-button version of the mouse was incorporated into the Apple Macintosh but Steve Jobs decided against incorporating the chorded keyset.
In the early 1980s, Philips Research labs at Redhill, Surrey did a brief study into small, cheap keyboards for entering text on a telephone. One solution used a grid of hexagonal keys with symbols inscribed into dimples in the keys that were either in the center of a key, across the boundary of two keys, or at the joining of three keys. Pressing down on one of the dimples would cause either one, two or three of the hexagonal buttons to be depressed at the same time, forming a chord that would be unique to that symbol. With this arrangement, a nine button keyboard with three rows of three hexagonal buttons could be fitted onto a telephone and could produce up to 33 different symbols. By choosing widely separated keys, one could employ one dimple as a 'shift' key to allow both letters and numbers to be produced. With eleven keys in a 3/4/4 arrangement, 43 symbols could be arranged allowing for lowercase text, numbers and a modest number of punctuation symbols to be represented along with a 'shift' function for accessing uppercase letters. While this had the advantage of being usable by untrained users via 'hunt and peck' typing and requiring one less key switch than a conventional 12 button keypad, it had the disadvantage that some symbols required three times as much force to depress them as others which made it hard to achieve any speed with the device. That solution is still alive and proposed by Fastap and Unitap among others, and a commercial phone has been produced and promoted in Canada during 2006.
Historically, the baudot and braille keyboards were standardized to some extent, but they are unable to replicate the full character set of a modern keyboard. Braille comes closest, as it has been extended to eight bits.
The only proposed modern standard, GKOS (or Global Keyboard Open Standard) can support most characters and functions found on a computer keyboard but has had little commercial development. There is, however, a GKOS keyboard application available for iPhone since May 8, 2010, for Android since October 3, 2010 and for MeeGo Harmattan since October 27, 2011.
Stenotype machines (sometimes used by court reporters) use a chording keyboard to represent sounds: on the standard keyboard, the U represents the sound (and word) 'you', and the three-key trigraph KAT represents the sound and word 'cat'. The stenotype keyboard is explicitly ordered: in KAT, K, on the left, is the starting sound. P, S, and T, which are common starting sounds and also common ending sounds, are available on both sides of the keyboard: POP is a 3-key chord, using both P keys. .
Four open-source keyer/keyset designs are available: The pickey, a PS/2 device based on the PIC microcontroller; the spiffchorder, a USB device based on the Atmel AVR family of microcontrollers; the FeatherChorder, a BLE chorder based on the Adafruit Feather, an all-in-one board incorporating an Arduino-compatible microcontroller; and the GKOS keypad driver for Linux as well as the Gkos library for the Atmel/Arduino open-source board.
Plover is a free, open-source, cross-platform program intended to bring real-time stenographic technology not just to stenographers, but also to hobbyists using anything from professional Stenotype machines to low-cost NKRO gaming keyboards. It is available for Linux, Windows, and macOS.
Joy2chord is a chorded keyboard driver for Linux. With a configuration file, any joystick or gamepad can be turned into a chorded keyboard. This design philosophy was decided on to lower the cost of building devices, and in turn lower the entry barrier to becoming familiar with chorded keyboards. Macro keys, and multiple modes are also easily implemented with a user space driver.
One minimal chordic keyboard example is Edgar Matias' Half-Qwerty keyboard described in patent US 5288158 circa 1992 that produces the letters of the missing half when the user simultaneously presses the space bar along with the mirror key. INTERCHI '93 published a study by Matias, MacKenzie and Buxton showing that people who have already learned to touch-type can quickly recover 50 to 70% of their two-handed typing speed. The loss contributes to the speed discussion above. It is implemented on two popular mobile phones, each provided with software disambiguation, which allows users to avoid using the space-bar.
"Multiambic" keyers for use with wearable computers were invented in Canada in the 1970s. Multiambic keyers are similar to chording keyboards but without the board, in that the keys are grouped in a cluster for being handheld, rather than for sitting on a flat surface.
Chording keyboards are also used as portable but two handed input devices for the visually impaired (either combined with a refreshable braille display or vocal synthesis). Such keyboards use a minimum of seven keys, where each key corresponds to an individual braille point, except one key which is used as a spacebar. In some applications, the spacebar is used to produce additional chords which enable the user to issue editing commands, such as moving the cursor, or deleting words. Note that the number of points used in braille computing is not 6, but 8, as this allows the user, among other things, to distinguish between small and capital letters, as well as identify the position of the cursor. As a result, most newer chorded keyboards for braille input include at least nine keys.
Touch screen chordic keyboards are available to smartphone users as an optional way of entering text. As the number of keys is low, the button areas can be made bigger and easier to hit on the small screen. The most common letters do not necessarily require chording as is the case with the GKOS keyboard optimised layouts (Android app) where the twelve most frequent characters only require single keys.
The company CharaChorder commerially sells chorded entry devices. Their first commercially available device is the CharaChorder One, which features a split design with each having access to 9 switches that can be moved in five directions (up, down, left, right, and pressed) in contrast to typical keyboards. This device allows for both chorded entry as well as traditional character entry. The set of words that can be chorded can be dynamically changed by the user in real time, but by default includes the 300 most common words in the English language. This chorded entry feature allows for potentially extremely fast typing speeds, so much so the founder of the company has been banned from online typing competitions. Additionally, they create the Charachorder Lite with a more traditional keyboard design. The manufacturer claimed that users of the Charachorder One can reach speeds of 300 words per minute, while users of the Charachorder Lite can reach 250 words per minute.
The WriteHander, a 12-key chord keyboard from NewO Company, appeared in 1978 issues of ROM Magazine, an early microcomputer applications magazine.
Another early commercial model was the six-button Microwriter, designed by Cy Endfield and Chris Rainey, and first sold in 1980. Microwriting is the system of chord keying and is based on a set of mnemonics. It was designed only for right-handed use.
In 1982 the Octima 8 keys cord keyboard was presented by Ergoplic Kebords Ltd an Israeli Startup that was founded by Israeli researcher with intensive experience in Man Machine Interface design. The keyboard had 8 keys one for each finger and additional 3 keys that enabled the production of numbers, punctuations and control functions. The keyboard was fully compatible with the IBM PC and AT keyboards and had an Apple IIe version as well. Its key combinations were based on a mnemonic system that enabled fast and easy touch type learning. Within a few hours the user could achieve a typing speed similar to hand writing speed. The unique design also gave a relief from hand stress (Carpal Tunnel Syndrome) and allowed longer typing sessions than traditional keyboards. It was multi-lingual supporting English, German, French and Hebrew.
The BAT is a 7-key hand-sized device from Infogrip, and has been sold since 1985. It provides one key for each finger and three for the thumb. It is proposed for the hand which does not hold the mouse, in an exact continuation of Engelbart's vision. | [
{
"paragraph_id": 0,
"text": "A keyset or chorded keyboard (also called a chorded keyset, chord keyboard or chording keyboard) is a computer input device that allows the user to enter characters or commands formed by pressing several keys together, like playing a \"chord\" on a piano. The large number of combinations available from a small number of keys allows text or commands to be entered with one hand, leaving the other hand free. A secondary advantage is that it can be built into a device (such as a pocket-sized computer or a bicycle handlebar) that is too small to contain a normal-sized keyboard.",
"title": ""
},
{
"paragraph_id": 1,
"text": "A chorded keyboard minus the board, typically designed to be used while held in the hand, is called a keyer. Douglas Engelbart introduced the chorded keyset as a computer interface in 1968 at what is often called \"The Mother of All Demos\".",
"title": ""
},
{
"paragraph_id": 2,
"text": "Each key is mapped to a number and then can be mapped to a corresponding letter or command. By pressing two or more keys together the user can generate many combinations. In Engelbart's original mapping, he used five keys: 1, 2, 4, 8, 16. The keys were mapped as follows: a = 1, b = 2, c = 3, d = 4, and so on. If the user pressed keys 1 and 2 simultaneously, and then released the keys, 1 and 2 would be added to 3, and since C is the 3rd letter of the alphabet, and the letter \"c\" appeared. Unlike pressing a chord on a piano, the chord is recognized only after all the keys or mouse buttons are released. Since Engelbart introduced the keyset, several different designs have been developed based on similar concepts.",
"title": "Principles of operation"
},
{
"paragraph_id": 3,
"text": "As a crude example, each finger might control one key which corresponds to one bit in a byte, so that using seven keys and seven fingers, one could enter any character in the ASCII set—if the user could remember the binary codes. Due to the small number of keys required, chording is easily adapted from a desktop to mobile environment.",
"title": "Principles of operation"
},
{
"paragraph_id": 4,
"text": "Practical devices generally use simpler chords for common characters (e.g., Baudot), or may have ways to make it easier to remember the chords (e.g., Microwriter), but the same principles apply. These portable devices first became popular with the wearable computer movement in the 1980s.",
"title": "Principles of operation"
},
{
"paragraph_id": 5,
"text": "Thad Starner from Georgia Institute of Technology and others published numerous studies showing that two-handed chorded text entry was faster and yielded fewer errors than on a QWERTY keyboard. Currently stenotype machines hold the record for fastest word entry. Many stenotype users can reach 300 words per minute. However, stenographers typically train for three years before reaching professional levels of speed and accuracy.",
"title": "Principles of operation"
},
{
"paragraph_id": 6,
"text": "The earliest known chord keyboard was part of the \"five-needle\" telegraph operator station, designed by Wheatstone and Cooke in 1836, in which any two of the five needles could point left or right to indicate letters on a grid. It was designed to be used by untrained operators (who would determine which keys to press by looking at the grid), and was not used where trained telegraph operators were available.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "The first widespread use of a chord keyboard was in the stenotype machine used by court reporters, which was invented in 1868 and is still in use. The output of the stenotype was originally a phonetic code that had to be transcribed later (usually by the same operator who produced the original output), rather than arbitrary text—automatic conversion software is now commonplace.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "In 1874, the five-bit Baudot telegraph code and a matching 5-key chord keyboard was designed to be used with the operator forming the codes manually. The code is optimized for speed and low wear: chords were chosen so that the most common characters used the simplest chords. But telegraph operators were already using typewriters with QWERTY keyboards to \"copy\" received messages, and at the time it made more sense to build a typewriter that could generate the codes automatically, rather than making them learn to use a new input device.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "Some early keypunch machines used a keyboard with 12 labeled keys to punch the correct holes in paper cards. The numbers 0 through 9 were represented by one punch; 26 letters were represented by combinations of two punches, and symbols were represented by combinations of two or three punches.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "Braille (a writing system for the blind) uses either 6 or 8 tactile 'points' from which all letters and numbers are formed. When Louis Braille invented it, it was produced with a needle holing successively all needed points in a cardboard sheet. In 1892, Frank Haven Hall, superintendent of the Illinois Institute for the Education of the Blind, created the Hall Braille Writer, which was like a typewriter with 6 keys, one for each dot in a braille cell. The Perkins Brailler, first manufactured in 1951, uses a 6-key chord keyboard (plus a spacebar) to produce braille output, and has been very successful as a mass market affordable product. Braille, like Baudot, uses a number symbol and a shift symbol, which may be repeated for shift lock, to fit numbers and upper case into the 63 codes that 6 bits offer.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "After World War II, with the arrival of electronics for reading chords and looking in tables of \"codes\", the postal sorting offices started to research chordic solutions to be able to employ people other than trained and expensive typists. In 1954, an important concept was discovered: chordic production is easier to master when the production is done at the release of the keys instead of when they are pressed.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "Researchers at IBM investigated chord keyboards for both typewriters and computer data entry as early as 1959, with the idea that it might be faster than touch-typing if some chords were used to enter whole words or parts of words. A 1975 design by IBM Fellow Nat Rochester had 14 keys that were dimpled on the edges as well as the top, so one finger could press two adjacent keys for additional combinations. Their results were inconclusive, but research continued until at least 1978.",
"title": "History"
},
{
"paragraph_id": 13,
"text": "Doug Engelbart began experimenting with keysets to use with the mouse in the mid 1960s. In a famous 1968 demonstration, Engelbart introduced a computer human interface that included the QWERTY keyboard, a three button mouse, and a five key keyset. Engelbart used the keyset with his left hand and the mouse with his right to type text and enter commands. The mouse buttons marked selections and confirmed or aborted commands.",
"title": "History"
},
{
"paragraph_id": 14,
"text": "Users in Engelbart's Augmentation Research Center at SRI became proficient with the mouse and keyset. In the 1970s the funding Engelbart's group received from the Advanced Research Projects Agency (ARPA) was cut and many key members of Engelbart's team went to work for Xerox PARC where they continued to experiment with the mouse and keyset. Keychord sets were used at Xerox PARC in the early 1980s, along with mice, GUIs, on the Xerox Star and Alto workstations. A one-button version of the mouse was incorporated into the Apple Macintosh but Steve Jobs decided against incorporating the chorded keyset.",
"title": "History"
},
{
"paragraph_id": 15,
"text": "In the early 1980s, Philips Research labs at Redhill, Surrey did a brief study into small, cheap keyboards for entering text on a telephone. One solution used a grid of hexagonal keys with symbols inscribed into dimples in the keys that were either in the center of a key, across the boundary of two keys, or at the joining of three keys. Pressing down on one of the dimples would cause either one, two or three of the hexagonal buttons to be depressed at the same time, forming a chord that would be unique to that symbol. With this arrangement, a nine button keyboard with three rows of three hexagonal buttons could be fitted onto a telephone and could produce up to 33 different symbols. By choosing widely separated keys, one could employ one dimple as a 'shift' key to allow both letters and numbers to be produced. With eleven keys in a 3/4/4 arrangement, 43 symbols could be arranged allowing for lowercase text, numbers and a modest number of punctuation symbols to be represented along with a 'shift' function for accessing uppercase letters. While this had the advantage of being usable by untrained users via 'hunt and peck' typing and requiring one less key switch than a conventional 12 button keypad, it had the disadvantage that some symbols required three times as much force to depress them as others which made it hard to achieve any speed with the device. That solution is still alive and proposed by Fastap and Unitap among others, and a commercial phone has been produced and promoted in Canada during 2006.",
"title": "History"
},
{
"paragraph_id": 16,
"text": "Historically, the baudot and braille keyboards were standardized to some extent, but they are unable to replicate the full character set of a modern keyboard. Braille comes closest, as it has been extended to eight bits.",
"title": "Standards"
},
{
"paragraph_id": 17,
"text": "The only proposed modern standard, GKOS (or Global Keyboard Open Standard) can support most characters and functions found on a computer keyboard but has had little commercial development. There is, however, a GKOS keyboard application available for iPhone since May 8, 2010, for Android since October 3, 2010 and for MeeGo Harmattan since October 27, 2011.",
"title": "Standards"
},
{
"paragraph_id": 18,
"text": "Stenotype machines (sometimes used by court reporters) use a chording keyboard to represent sounds: on the standard keyboard, the U represents the sound (and word) 'you', and the three-key trigraph KAT represents the sound and word 'cat'. The stenotype keyboard is explicitly ordered: in KAT, K, on the left, is the starting sound. P, S, and T, which are common starting sounds and also common ending sounds, are available on both sides of the keyboard: POP is a 3-key chord, using both P keys. .",
"title": "Stenography"
},
{
"paragraph_id": 19,
"text": "Four open-source keyer/keyset designs are available: The pickey, a PS/2 device based on the PIC microcontroller; the spiffchorder, a USB device based on the Atmel AVR family of microcontrollers; the FeatherChorder, a BLE chorder based on the Adafruit Feather, an all-in-one board incorporating an Arduino-compatible microcontroller; and the GKOS keypad driver for Linux as well as the Gkos library for the Atmel/Arduino open-source board.",
"title": "Open-source designs"
},
{
"paragraph_id": 20,
"text": "Plover is a free, open-source, cross-platform program intended to bring real-time stenographic technology not just to stenographers, but also to hobbyists using anything from professional Stenotype machines to low-cost NKRO gaming keyboards. It is available for Linux, Windows, and macOS.",
"title": "Open-source designs"
},
{
"paragraph_id": 21,
"text": "Joy2chord is a chorded keyboard driver for Linux. With a configuration file, any joystick or gamepad can be turned into a chorded keyboard. This design philosophy was decided on to lower the cost of building devices, and in turn lower the entry barrier to becoming familiar with chorded keyboards. Macro keys, and multiple modes are also easily implemented with a user space driver.",
"title": "Open-source designs"
},
{
"paragraph_id": 22,
"text": "One minimal chordic keyboard example is Edgar Matias' Half-Qwerty keyboard described in patent US 5288158 circa 1992 that produces the letters of the missing half when the user simultaneously presses the space bar along with the mirror key. INTERCHI '93 published a study by Matias, MacKenzie and Buxton showing that people who have already learned to touch-type can quickly recover 50 to 70% of their two-handed typing speed. The loss contributes to the speed discussion above. It is implemented on two popular mobile phones, each provided with software disambiguation, which allows users to avoid using the space-bar.",
"title": "Commercial devices"
},
{
"paragraph_id": 23,
"text": "\"Multiambic\" keyers for use with wearable computers were invented in Canada in the 1970s. Multiambic keyers are similar to chording keyboards but without the board, in that the keys are grouped in a cluster for being handheld, rather than for sitting on a flat surface.",
"title": "Commercial devices"
},
{
"paragraph_id": 24,
"text": "Chording keyboards are also used as portable but two handed input devices for the visually impaired (either combined with a refreshable braille display or vocal synthesis). Such keyboards use a minimum of seven keys, where each key corresponds to an individual braille point, except one key which is used as a spacebar. In some applications, the spacebar is used to produce additional chords which enable the user to issue editing commands, such as moving the cursor, or deleting words. Note that the number of points used in braille computing is not 6, but 8, as this allows the user, among other things, to distinguish between small and capital letters, as well as identify the position of the cursor. As a result, most newer chorded keyboards for braille input include at least nine keys.",
"title": "Commercial devices"
},
{
"paragraph_id": 25,
"text": "Touch screen chordic keyboards are available to smartphone users as an optional way of entering text. As the number of keys is low, the button areas can be made bigger and easier to hit on the small screen. The most common letters do not necessarily require chording as is the case with the GKOS keyboard optimised layouts (Android app) where the twelve most frequent characters only require single keys.",
"title": "Commercial devices"
},
{
"paragraph_id": 26,
"text": "The company CharaChorder commerially sells chorded entry devices. Their first commercially available device is the CharaChorder One, which features a split design with each having access to 9 switches that can be moved in five directions (up, down, left, right, and pressed) in contrast to typical keyboards. This device allows for both chorded entry as well as traditional character entry. The set of words that can be chorded can be dynamically changed by the user in real time, but by default includes the 300 most common words in the English language. This chorded entry feature allows for potentially extremely fast typing speeds, so much so the founder of the company has been banned from online typing competitions. Additionally, they create the Charachorder Lite with a more traditional keyboard design. The manufacturer claimed that users of the Charachorder One can reach speeds of 300 words per minute, while users of the Charachorder Lite can reach 250 words per minute.",
"title": "Commercial devices"
},
{
"paragraph_id": 27,
"text": "The WriteHander, a 12-key chord keyboard from NewO Company, appeared in 1978 issues of ROM Magazine, an early microcomputer applications magazine.",
"title": "Commercial devices"
},
{
"paragraph_id": 28,
"text": "Another early commercial model was the six-button Microwriter, designed by Cy Endfield and Chris Rainey, and first sold in 1980. Microwriting is the system of chord keying and is based on a set of mnemonics. It was designed only for right-handed use.",
"title": "Commercial devices"
},
{
"paragraph_id": 29,
"text": "In 1982 the Octima 8 keys cord keyboard was presented by Ergoplic Kebords Ltd an Israeli Startup that was founded by Israeli researcher with intensive experience in Man Machine Interface design. The keyboard had 8 keys one for each finger and additional 3 keys that enabled the production of numbers, punctuations and control functions. The keyboard was fully compatible with the IBM PC and AT keyboards and had an Apple IIe version as well. Its key combinations were based on a mnemonic system that enabled fast and easy touch type learning. Within a few hours the user could achieve a typing speed similar to hand writing speed. The unique design also gave a relief from hand stress (Carpal Tunnel Syndrome) and allowed longer typing sessions than traditional keyboards. It was multi-lingual supporting English, German, French and Hebrew.",
"title": "Commercial devices"
},
{
"paragraph_id": 30,
"text": "The BAT is a 7-key hand-sized device from Infogrip, and has been sold since 1985. It provides one key for each finger and three for the thumb. It is proposed for the hand which does not hold the mouse, in an exact continuation of Engelbart's vision.",
"title": "Commercial devices"
}
] | A keyset or chorded keyboard is a computer input device that allows the user to enter characters or commands formed by pressing several keys together, like playing a "chord" on a piano. The large number of combinations available from a small number of keys allows text or commands to be entered with one hand, leaving the other hand free. A secondary advantage is that it can be built into a device that is too small to contain a normal-sized keyboard. A chorded keyboard minus the board, typically designed to be used while held in the hand, is called a keyer. Douglas Engelbart introduced the chorded keyset as a computer interface in 1968 at what is often called "The Mother of All Demos". | 2001-09-14T00:33:16Z | 2023-12-29T20:49:19Z | [
"Template:Reflist",
"Template:Cite journal",
"Template:Cite news",
"Template:ISBN",
"Template:Keyboard layouts",
"Template:Short description",
"Template:Dubious",
"Template:Cite web",
"Template:Cite book",
"Template:Cite patent",
"Template:Citation",
"Template:Citation needed",
"Template:Patent"
] | https://en.wikipedia.org/wiki/Chorded_keyboard |
6,337 | Carolyn Beug | Carolyn Ann Mayer-Beug (December 11, 1952 – September 11, 2001) was a filmmaker and video producer from Santa Monica, California. She died in the September 11 attacks as a passenger of the American Airlines Flight 11.
In addition to her work as video producer, Beug also directed three music videos for country singer Dwight Yoakam: "Ain't That Lonely Yet", "A Thousand Miles from Nowhere" and "Fast as You." Beug co-directed the former two videos with Yoakam and was the sole director of the latter video. She won an MTV Video Music award for the Van Halen music video of the song "Right Now", which she produced. She also served as senior vice president of Walt Disney Records.
Beug lived in a Tudor-style home in the North 25th Street neighborhood. She hosted an annual backyard barbecue for the Santa Monica High School cross country and track team, which her daughters captained. Beug was a Latter-day Saint.
Beug was killed at the age of 48 in the crash of American Airlines Flight 11 in the September 11, 2001 attacks. At the time of her death, Carolyn Beug was working on a children's book about Noah's Ark which was to be told from Noah's wife's point of view. On the plane with her was her mother, Mary Alice Wahlstrom. Beug was survived by her twin eighteen-year-old daughters Lauren and Lindsey Mayer-Beug, her 13-year-old son, Nick, and her husband, John Beug, a senior vice president in charge of filmed production for Warner Brothers' record division. She was returning home from taking her daughters to college at the Rhode Island School of Design.
At the National 9/11 Memorial, Beug is memorialized at the North Pool, on Panel N-1. | [
{
"paragraph_id": 0,
"text": "Carolyn Ann Mayer-Beug (December 11, 1952 – September 11, 2001) was a filmmaker and video producer from Santa Monica, California. She died in the September 11 attacks as a passenger of the American Airlines Flight 11.",
"title": ""
},
{
"paragraph_id": 1,
"text": "In addition to her work as video producer, Beug also directed three music videos for country singer Dwight Yoakam: \"Ain't That Lonely Yet\", \"A Thousand Miles from Nowhere\" and \"Fast as You.\" Beug co-directed the former two videos with Yoakam and was the sole director of the latter video. She won an MTV Video Music award for the Van Halen music video of the song \"Right Now\", which she produced. She also served as senior vice president of Walt Disney Records.",
"title": "Career"
},
{
"paragraph_id": 2,
"text": "Beug lived in a Tudor-style home in the North 25th Street neighborhood. She hosted an annual backyard barbecue for the Santa Monica High School cross country and track team, which her daughters captained. Beug was a Latter-day Saint.",
"title": "Personal life"
},
{
"paragraph_id": 3,
"text": "Beug was killed at the age of 48 in the crash of American Airlines Flight 11 in the September 11, 2001 attacks. At the time of her death, Carolyn Beug was working on a children's book about Noah's Ark which was to be told from Noah's wife's point of view. On the plane with her was her mother, Mary Alice Wahlstrom. Beug was survived by her twin eighteen-year-old daughters Lauren and Lindsey Mayer-Beug, her 13-year-old son, Nick, and her husband, John Beug, a senior vice president in charge of filmed production for Warner Brothers' record division. She was returning home from taking her daughters to college at the Rhode Island School of Design.",
"title": "Death and legacy"
},
{
"paragraph_id": 4,
"text": "At the National 9/11 Memorial, Beug is memorialized at the North Pool, on Panel N-1.",
"title": "Death and legacy"
}
] | Carolyn Ann Mayer-Beug was a filmmaker and video producer from Santa Monica, California. She died in the September 11 attacks as a passenger of the American Airlines Flight 11. | 2001-09-14T04:38:28Z | 2023-12-17T01:12:10Z | [
"Template:Infobox person",
"Template:Cite web",
"Template:Cite news",
"Template:Webarchive",
"Template:Commons category",
"Template:Authority control",
"Template:Short description",
"Template:Reflist",
"Template:IMDb name",
"Template:Find a Grave"
] | https://en.wikipedia.org/wiki/Carolyn_Beug |
6,339 | Cell biology | Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. Cell biology is the study of the structural and functional units of cells. Cell biology encompasses both prokaryotic and eukaryotic cells and has many subtopics which may include the study of cell metabolism, cell communication, cell cycle, biochemistry, and cell composition. The study of cells is performed using several microscopy techniques, cell culture, and cell fractionation. These have allowed for and are currently being used for discoveries and research pertaining to how cells function, ultimately giving insight into understanding larger organisms. Knowing the components of cells and how cells work is fundamental to all biological sciences while also being essential for research in biomedical fields such as cancer, and other diseases. Research in cell biology is interconnected to other fields such as genetics, molecular genetics, molecular biology, medical microbiology, immunology, and cytochemistry.
Cells were first seen in 17th-century Europe with the invention of the compound microscope. In 1665, Robert Hooke referred to the building blocks of all living organisms as "cells" (published in Micrographia) after looking at a piece of cork and observing a cell-like structure; however, the cells were dead. They gave no indication to the actual overall components of a cell. A few years later, in 1674, Anton Van Leeuwenhoek was the first to analyze live cells in his examination of algae. All of this preceded the cell theory which states that all living things are made up of cells and that cells are organisms' functional and structural units. This was ultimately concluded by plant scientist Matthias Schleiden and animal scientist Theodor Schwann in 1838, who viewed live cells in plant and animal tissue, respectively. 19 years later, Rudolf Virchow further contributed to the cell theory, adding that all cells come from the division of pre-existing cells. Viruses are not considered in cell biology – they lack the characteristics of a living cell and instead are studied in the microbiology subclass of virology.
Cell biology research looks at different ways to culture and manipulate cells outside of a living body to further research in human anatomy and physiology, and to derive medications.The techniques by which cells are studied have evolved. Due to advancements in microscopy, techniques and technology have allowed scientists to hold a better understanding of the structure and function of cells. Many techniques commonly used to study cell biology are listed below:
There are two fundamental classifications of cells: prokaryotic and eukaryotic. Prokaryotic cells are distinguished from eukaryotic cells by the absence of a cell nucleus or other membrane-bound organelle. Prokaryotic cells are much smaller than eukaryotic cells, making them the smallest form of life. Prokaryotic cells include Bacteria and Archaea, and lack an enclosed cell nucleus. Eukaryotic cells are found in plants, animals, fungi, and protists. They range from 10 to 100 μm in diameter, and their DNA is contained within a membrane-bound nucleus. Eukaryotes are organisms containing eukaryotic cells. The four eukaryotic kingdoms are Animalia, Plantae, Fungi, and Protista.
They both reproduce through binary fission. Bacteria, the most prominent type, have several different shapes, although most are spherical or rod-shaped. Bacteria can be classed as either gram-positive or gram-negative depending on the cell wall composition. Gram-positive bacteria have a thicker peptidoglycan layer than gram-negative bacteria. Bacterial structural features include a flagellum that helps the cell to move, ribosomes for the translation of RNA to protein, and a nucleoid that holds all the genetic material in a circular structure. There are many processes that occur in prokaryotic cells that allow them to survive. In prokaryotes, mRNA synthesis is initiated at a promoter sequence on the DNA template comprising two consensus sequences that recruit RNA polymerase. The prokaryotic polymerase consists of a core enzyme of four protein subunits and a σ protein that assists only with initiation. For instance, in a process termed conjugation, the fertility factor allows the bacteria to possess a pilus which allows it to transmit DNA to another bacteria which lacks the F factor, permitting the transmittance of resistance allowing it to survive in certain environments.
Eukaryotic cells are composed of the following organelles:
Eukaryotic cells may also be composed of the following molecular components:
Cell metabolism is necessary for the production of energy for the cell and therefore its survival and includes many pathways and also sustaining the main cell organelles such as the nucleus, the mitochondria, the cell membrane etc. For cellular respiration, once glucose is available, glycolysis occurs within the cytosol of the cell to produce pyruvate. Pyruvate undergoes decarboxylation using the multi-enzyme complex to form acetyl coA which can readily be used in the TCA cycle to produce NADH and FADH2. These products are involved in the electron transport chain to ultimately form a proton gradient across the inner mitochondrial membrane. This gradient can then drive the production of ATP and H2O during oxidative phosphorylation. Metabolism in plant cells includes photosynthesis which is simply the exact opposite of respiration as it ultimately produces molecules of glucose.
Cell signaling or cell communication is important for cell regulation and for cells to process information from the environment and respond accordingly. Signaling can occur through direct cell contact or endocrine, paracrine, and autocrine signaling. Direct cell-cell contact is when a receptor on a cell binds a molecule that is attached to the membrane of another cell. Endocrine signaling occurs through molecules secreted into the bloodstream. Paracrine signaling uses molecules diffusing between two cells to communicate. Autocrine is a cell sending a signal to itself by secreting a molecule that binds to a receptor on its surface. Forms of communication can be through:
Cells are the foundation of all organisms and are the fundamental units of life. The growth and development of cells are essential for the maintenance of the host and survival of the organism. For this process, the cell goes through the steps of the cell cycle and development which involves cell growth, DNA replication, cell division, regeneration, and cell death.
The cell cycle is divided into four distinct phases: G1, S, G2, and M. The G phase – which is the cell growth phase – makes up approximately 95% of the cycle. The proliferation of cells is instigated by progenitors. All cells start out in an identical form and can essentially become any type of cells. Cell signaling such as induction can influence nearby cells to determinate the type of cell it will become. Moreover, this allows cells of the same type to aggregate and form tissues, then organs, and ultimately systems. The G1, G2, and S phase (DNA replication, damage and repair) are considered to be the interphase portion of the cycle, while the M phase (mitosis) is the cell division portion of the cycle. Mitosis is composed of many stages which include, prophase, metaphase, anaphase, telophase, and cytokinesis, respectively. The ultimate result of mitosis is the formation of two identical daughter cells.
The cell cycle is regulated in cell cycle checkpoints, by a series of signaling factors and complexes such as cyclins, cyclin-dependent kinase, and p53. When the cell has completed its growth process and if it is found to be damaged or altered, it undergoes cell death, either by apoptosis or necrosis, to eliminate the threat it can cause to the organism's survival.
The ancestry of each present day cell presumably traces back, in an unbroken lineage for over 3 billion years to the origin of life. It is not actually cells that are immortal but multi-generational cell lineages. The immortality of a cell lineage depends on the maintenance of cell division potential. This potential may be lost in any particular lineage because of cell damage, terminal differentiation as occurs in nerve cells, or programmed cell death (apoptosis) during development. Maintenance of cell division potential over successive generations depends on the avoidance and the accurate repair of cellular damage, particularly DNA damage. In sexual organisms, continuity of the germline depends on the effectiveness of processes for avoiding DNA damage and repairing those DNA damages that do occur. Sexual processes in eukaryotes, as well as in prokaryotes, provide an opportunity for effective repair of DNA damages in the germ line by homologous recombination.
The cell cycle is a four-stage process that a cell goes through as it develops and divides. It includes Gap 1 (G1), synthesis (S), Gap 2 (G2), and mitosis (M).The cell either restarts the cycle from G1 or leaves the cycle through G0 after completing the cycle. The cell can progress from G0 through terminal differentiation.
The interphase refers to the phases of the cell cycle that occur between one mitosis and the next, and includes G1, S, and G2.
The size of the cell grows.
The contents of cells are replicated.
Replication of DNA
The cell replicates each of the 46 chromosomes (23 pairs).
The cell multiplies.
In preparation for cell division, organelles and proteins form.
After mitosis, cytokinesis occurs (cell separation)
Formation of two daughter cells that are identical
These cells leave G1 and enter G0, a resting stage. A cell in G0 is doing its job without actively preparing to divide.
The scientific branch that studies and diagnoses diseases on the cellular level is called cytopathology. Cytopathology is generally used on samples of free cells or tissue fragments, in contrast to the pathology branch of histopathology, which studies whole tissues. Cytopathology is commonly used to investigate diseases involving a wide range of body sites, often to aid in the diagnosis of cancer but also in the diagnosis of some infectious diseases and other inflammatory conditions. For example, a common application of cytopathology is the Pap smear, a screening test used to detect cervical cancer, and precancerous cervical lesions that may lead to cervical cancer.
The cell cycle is composed of a number of well-ordered, consecutive stages that result in cellular division. The fact that cells do not begin the next stage until the last one is finished, is a significant element of cell cycle regulation. Cell cycle checkpoints are characteristics that constitute an excellent monitoring strategy for accurate cell cycle and divisions. Cdks, associated cyclin counterparts, protein kinases, and phosphatases regulate cell growth and division from one stage to another. The cell cycle is controlled by the temporal activation of Cdks, which is governed by cyclin partner interaction, phosphorylation by particular protein kinases, and de-phosphorylation by Cdc25 family phosphatases. In response to DNA damage, a cell's DNA repair reaction is a cascade of signaling pathways that leads to checkpoint engagement, regulates, the repairing mechanism in DNA, cell cycle alterations, and apoptosis. Numerous biochemical structures, as well as processes that detect damage in DNA, are ATM and ATR, which induce the DNA repair checkpoints
The cell cycle is a sequence of activities in which cell organelles are duplicated and subsequently separated into daughter cells with precision. There are major events that happen during a cell cycle. The processes that happen in the cell cycle include cell development, replication and segregation of chromosomes. The cell cycle checkpoints are surveillance systems that keep track of the cell cycle's integrity, accuracy, and chronology. Each checkpoint serves as an alternative cell cycle endpoint, wherein the cell's parameters are examined and only when desirable characteristics are fulfilled does the cell cycle advance through the distinct steps. The cell cycle's goal is to precisely copy each organism's DNA and afterwards equally split the cell and its components between the two new cells. Four main stages occur in the eukaryotes. In G1, the cell is usually active and continues to grow rapidly, while in G2, the cell growth continues while protein molecules become ready for separation. These are not dormant times; they are when cells gain mass, integrate growth factor receptors, establish a replicated genome, and prepare for chromosome segregation. DNA replication is restricted to a separate Synthesis in eukaryotes, which is also known as the S-phase. During mitosis, which is also known as the M-phase, the segregation of the chromosomes occur. DNA, like every other molecule, is capable of undergoing a wide range of chemical reactions. Modifications in DNA's sequence, on the other hand, have a considerably bigger impact than modifications in other cellular constituents like RNAs or proteins because DNA acts as a permanent copy of the cell genome. When erroneous nucleotides are incorporated during DNA replication, mutations can occur. The majority of DNA damage is fixed by removing the defective bases and then re-synthesizing the excised area. On the other hand, some DNA lesions can be mended by reversing the damage, which may be a more effective method of coping with common types of DNA damage. Only a few forms of DNA damage are mended in this fashion, including pyrimidine dimers caused by ultraviolet (UV) light changed by the insertion of methyl or ethyl groups at the purine ring's O6 position.
Mitochondria are commonly referred to as the cell's "powerhouses" because of their capacity to effectively produce ATP which is essential to maintain cellular homeostasis and metabolism. Moreover, researchers have gained a better knowledge of mitochondria's significance in cell biology because of the discovery of cell signaling pathways by mitochondria which are crucial platforms for cell function regulation such as apoptosis. Its physiological adaptability is strongly linked to the cell mitochondrial channel's ongoing reconfiguration through a range of mechanisms known as mitochondrial membrane dynamics, which include endomembrane fusion and fragmentation (separation) as well as ultrastructural membrane remodeling. As a result, mitochondrial dynamics regulate and frequently choreograph not only metabolic but also complicated cell signaling processes such as cell pluripotent stem cells, proliferation, maturation, aging, and mortality. Mutually, post-translational alterations of mitochondrial apparatus and the development of transmembrane contact sites among mitochondria and other structures, which both have the potential to link signals from diverse routes that affect mitochondrial membrane dynamics substantially, Mitochondria are wrapped by two membranes: an inner mitochondrial membrane (IMM) and an outer mitochondrial membrane (OMM), each with a distinctive function and structure, which parallels their dual role as cellular powerhouses and signaling organelles. The inner mitochondrial membrane divides the mitochondrial lumen into two parts: the inner border membrane, which runs parallel to the OMM, and the cristae, which are deeply twisted, multinucleated invaginations that give room for surface area enlargement and house the mitochondrial respiration apparatus. The outer mitochondrial membrane, on the other hand, is soft and permeable. It, therefore, acts as a foundation for cell signaling pathways to congregate, be deciphered, and be transported into mitochondria. Furthermore, the OMM connects to other cellular organelles, such as the endoplasmic reticulum (ER), lysosomes, endosomes, and the plasma membrane. Mitochondria play a wide range of roles in cell biology, which is reflected in their morphological diversity. Ever since the beginning of the mitochondrial study, it has been well documented that mitochondria can have a variety of forms, with both their general and ultra-structural morphology varying greatly among cells, during the cell cycle, and in response to metabolic or cellular cues. Mitochondria can exist as independent organelles or as part of larger systems; they can also be unequally distributed in the cytosol through regulated mitochondrial transport and placement to meet the cell's localized energy requirements. Mitochondrial dynamics refers to the adaptive and variable aspect of mitochondria, including their shape and subcellular distribution.
Autophagy is a self-degradative mechanism that regulates energy sources during growth and reaction to dietary stress. Autophagy also cleans up after itself, clearing aggregated proteins, cleaning damaged structures including mitochondria and endoplasmic reticulum and eradicating intracellular infections. Additionally, autophagy has antiviral and antibacterial roles within the cell, and it is involved at the beginning of distinctive and adaptive immune responses to viral and bacterial contamination. Some viruses include virulence proteins that prevent autophagy, while others utilize autophagy elements for intracellular development or cellular splitting. Macro autophagy, micro autophagy, and chaperon-mediated autophagy are the three basic types of autophagy. When macro autophagy is triggered, an exclusion membrane incorporates a section of the cytoplasm, generating the autophagosome, a distinctive double-membraned organelle. The autophagosome then joins the lysosome to create an autolysosome, with lysosomal enzymes degrading the components. In micro autophagy, the lysosome or vacuole engulfs a piece of the cytoplasm by invaginating or protruding the lysosomal membrane to enclose the cytosol or organelles. The chaperone-mediated autophagy (CMA) protein quality assurance by digesting oxidized and altered proteins under stressful circumstances and supplying amino acids through protein denaturation. Autophagy is the primary intrinsic degradative system for peptides, fats, carbohydrates, and other cellular structures. In both physiologic and stressful situations, this cellular progression is vital for upholding the correct cellular balance. Autophagy instability leads to a variety of illness symptoms, including inflammation, biochemical disturbances, aging, and neurodegenerative, due to its involvement in controlling cell integrity. The modification of the autophagy-lysosomal networks is a typical hallmark of many neurological and muscular illnesses. As a result, autophagy has been identified as a potential strategy for the prevention and treatment of various disorders. Many of these disorders are prevented or improved by consuming polyphenol in the meal. As a result, natural compounds with the ability to modify the autophagy mechanism are seen as a potential therapeutic option. The creation of the double membrane (phagophore), which would be known as nucleation, is the first step in macro-autophagy. The phagophore approach indicates dysregulated polypeptides or defective organelles that come from the cell membrane, Golgi apparatus, endoplasmic reticulum, and mitochondria. With the conclusion of the autophagocyte, the phagophore's enlargement comes to an end. The auto-phagosome combines with the lysosomal vesicles to formulate an auto-lysosome that degrades the encapsulated substances, referred to as phagocytosis. | [
{
"paragraph_id": 0,
"text": "Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. Cell biology is the study of the structural and functional units of cells. Cell biology encompasses both prokaryotic and eukaryotic cells and has many subtopics which may include the study of cell metabolism, cell communication, cell cycle, biochemistry, and cell composition. The study of cells is performed using several microscopy techniques, cell culture, and cell fractionation. These have allowed for and are currently being used for discoveries and research pertaining to how cells function, ultimately giving insight into understanding larger organisms. Knowing the components of cells and how cells work is fundamental to all biological sciences while also being essential for research in biomedical fields such as cancer, and other diseases. Research in cell biology is interconnected to other fields such as genetics, molecular genetics, molecular biology, medical microbiology, immunology, and cytochemistry.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Cells were first seen in 17th-century Europe with the invention of the compound microscope. In 1665, Robert Hooke referred to the building blocks of all living organisms as \"cells\" (published in Micrographia) after looking at a piece of cork and observing a cell-like structure; however, the cells were dead. They gave no indication to the actual overall components of a cell. A few years later, in 1674, Anton Van Leeuwenhoek was the first to analyze live cells in his examination of algae. All of this preceded the cell theory which states that all living things are made up of cells and that cells are organisms' functional and structural units. This was ultimately concluded by plant scientist Matthias Schleiden and animal scientist Theodor Schwann in 1838, who viewed live cells in plant and animal tissue, respectively. 19 years later, Rudolf Virchow further contributed to the cell theory, adding that all cells come from the division of pre-existing cells. Viruses are not considered in cell biology – they lack the characteristics of a living cell and instead are studied in the microbiology subclass of virology.",
"title": "History"
},
{
"paragraph_id": 2,
"text": "Cell biology research looks at different ways to culture and manipulate cells outside of a living body to further research in human anatomy and physiology, and to derive medications.The techniques by which cells are studied have evolved. Due to advancements in microscopy, techniques and technology have allowed scientists to hold a better understanding of the structure and function of cells. Many techniques commonly used to study cell biology are listed below:",
"title": "Techniques"
},
{
"paragraph_id": 3,
"text": "There are two fundamental classifications of cells: prokaryotic and eukaryotic. Prokaryotic cells are distinguished from eukaryotic cells by the absence of a cell nucleus or other membrane-bound organelle. Prokaryotic cells are much smaller than eukaryotic cells, making them the smallest form of life. Prokaryotic cells include Bacteria and Archaea, and lack an enclosed cell nucleus. Eukaryotic cells are found in plants, animals, fungi, and protists. They range from 10 to 100 μm in diameter, and their DNA is contained within a membrane-bound nucleus. Eukaryotes are organisms containing eukaryotic cells. The four eukaryotic kingdoms are Animalia, Plantae, Fungi, and Protista.",
"title": "Cell types"
},
{
"paragraph_id": 4,
"text": "They both reproduce through binary fission. Bacteria, the most prominent type, have several different shapes, although most are spherical or rod-shaped. Bacteria can be classed as either gram-positive or gram-negative depending on the cell wall composition. Gram-positive bacteria have a thicker peptidoglycan layer than gram-negative bacteria. Bacterial structural features include a flagellum that helps the cell to move, ribosomes for the translation of RNA to protein, and a nucleoid that holds all the genetic material in a circular structure. There are many processes that occur in prokaryotic cells that allow them to survive. In prokaryotes, mRNA synthesis is initiated at a promoter sequence on the DNA template comprising two consensus sequences that recruit RNA polymerase. The prokaryotic polymerase consists of a core enzyme of four protein subunits and a σ protein that assists only with initiation. For instance, in a process termed conjugation, the fertility factor allows the bacteria to possess a pilus which allows it to transmit DNA to another bacteria which lacks the F factor, permitting the transmittance of resistance allowing it to survive in certain environments.",
"title": "Cell types"
},
{
"paragraph_id": 5,
"text": "Eukaryotic cells are composed of the following organelles:",
"title": "Structure and function"
},
{
"paragraph_id": 6,
"text": "Eukaryotic cells may also be composed of the following molecular components:",
"title": "Structure and function"
},
{
"paragraph_id": 7,
"text": "Cell metabolism is necessary for the production of energy for the cell and therefore its survival and includes many pathways and also sustaining the main cell organelles such as the nucleus, the mitochondria, the cell membrane etc. For cellular respiration, once glucose is available, glycolysis occurs within the cytosol of the cell to produce pyruvate. Pyruvate undergoes decarboxylation using the multi-enzyme complex to form acetyl coA which can readily be used in the TCA cycle to produce NADH and FADH2. These products are involved in the electron transport chain to ultimately form a proton gradient across the inner mitochondrial membrane. This gradient can then drive the production of ATP and H2O during oxidative phosphorylation. Metabolism in plant cells includes photosynthesis which is simply the exact opposite of respiration as it ultimately produces molecules of glucose.",
"title": "Structure and function"
},
{
"paragraph_id": 8,
"text": "Cell signaling or cell communication is important for cell regulation and for cells to process information from the environment and respond accordingly. Signaling can occur through direct cell contact or endocrine, paracrine, and autocrine signaling. Direct cell-cell contact is when a receptor on a cell binds a molecule that is attached to the membrane of another cell. Endocrine signaling occurs through molecules secreted into the bloodstream. Paracrine signaling uses molecules diffusing between two cells to communicate. Autocrine is a cell sending a signal to itself by secreting a molecule that binds to a receptor on its surface. Forms of communication can be through:",
"title": "Structure and function"
},
{
"paragraph_id": 9,
"text": "Cells are the foundation of all organisms and are the fundamental units of life. The growth and development of cells are essential for the maintenance of the host and survival of the organism. For this process, the cell goes through the steps of the cell cycle and development which involves cell growth, DNA replication, cell division, regeneration, and cell death.",
"title": "Growth and development"
},
{
"paragraph_id": 10,
"text": "The cell cycle is divided into four distinct phases: G1, S, G2, and M. The G phase – which is the cell growth phase – makes up approximately 95% of the cycle. The proliferation of cells is instigated by progenitors. All cells start out in an identical form and can essentially become any type of cells. Cell signaling such as induction can influence nearby cells to determinate the type of cell it will become. Moreover, this allows cells of the same type to aggregate and form tissues, then organs, and ultimately systems. The G1, G2, and S phase (DNA replication, damage and repair) are considered to be the interphase portion of the cycle, while the M phase (mitosis) is the cell division portion of the cycle. Mitosis is composed of many stages which include, prophase, metaphase, anaphase, telophase, and cytokinesis, respectively. The ultimate result of mitosis is the formation of two identical daughter cells.",
"title": "Growth and development"
},
{
"paragraph_id": 11,
"text": "The cell cycle is regulated in cell cycle checkpoints, by a series of signaling factors and complexes such as cyclins, cyclin-dependent kinase, and p53. When the cell has completed its growth process and if it is found to be damaged or altered, it undergoes cell death, either by apoptosis or necrosis, to eliminate the threat it can cause to the organism's survival.",
"title": "Growth and development"
},
{
"paragraph_id": 12,
"text": "The ancestry of each present day cell presumably traces back, in an unbroken lineage for over 3 billion years to the origin of life. It is not actually cells that are immortal but multi-generational cell lineages. The immortality of a cell lineage depends on the maintenance of cell division potential. This potential may be lost in any particular lineage because of cell damage, terminal differentiation as occurs in nerve cells, or programmed cell death (apoptosis) during development. Maintenance of cell division potential over successive generations depends on the avoidance and the accurate repair of cellular damage, particularly DNA damage. In sexual organisms, continuity of the germline depends on the effectiveness of processes for avoiding DNA damage and repairing those DNA damages that do occur. Sexual processes in eukaryotes, as well as in prokaryotes, provide an opportunity for effective repair of DNA damages in the germ line by homologous recombination.",
"title": "Growth and development"
},
{
"paragraph_id": 13,
"text": "The cell cycle is a four-stage process that a cell goes through as it develops and divides. It includes Gap 1 (G1), synthesis (S), Gap 2 (G2), and mitosis (M).The cell either restarts the cycle from G1 or leaves the cycle through G0 after completing the cycle. The cell can progress from G0 through terminal differentiation.",
"title": "Growth and development"
},
{
"paragraph_id": 14,
"text": "The interphase refers to the phases of the cell cycle that occur between one mitosis and the next, and includes G1, S, and G2.",
"title": "Growth and development"
},
{
"paragraph_id": 15,
"text": "The size of the cell grows.",
"title": "Growth and development"
},
{
"paragraph_id": 16,
"text": "The contents of cells are replicated.",
"title": "Growth and development"
},
{
"paragraph_id": 17,
"text": "Replication of DNA",
"title": "Growth and development"
},
{
"paragraph_id": 18,
"text": "The cell replicates each of the 46 chromosomes (23 pairs).",
"title": "Growth and development"
},
{
"paragraph_id": 19,
"text": "The cell multiplies.",
"title": "Growth and development"
},
{
"paragraph_id": 20,
"text": "In preparation for cell division, organelles and proteins form.",
"title": "Growth and development"
},
{
"paragraph_id": 21,
"text": "After mitosis, cytokinesis occurs (cell separation)",
"title": "Growth and development"
},
{
"paragraph_id": 22,
"text": "Formation of two daughter cells that are identical",
"title": "Growth and development"
},
{
"paragraph_id": 23,
"text": "These cells leave G1 and enter G0, a resting stage. A cell in G0 is doing its job without actively preparing to divide.",
"title": "Growth and development"
},
{
"paragraph_id": 24,
"text": "The scientific branch that studies and diagnoses diseases on the cellular level is called cytopathology. Cytopathology is generally used on samples of free cells or tissue fragments, in contrast to the pathology branch of histopathology, which studies whole tissues. Cytopathology is commonly used to investigate diseases involving a wide range of body sites, often to aid in the diagnosis of cancer but also in the diagnosis of some infectious diseases and other inflammatory conditions. For example, a common application of cytopathology is the Pap smear, a screening test used to detect cervical cancer, and precancerous cervical lesions that may lead to cervical cancer.",
"title": "Pathology"
},
{
"paragraph_id": 25,
"text": "The cell cycle is composed of a number of well-ordered, consecutive stages that result in cellular division. The fact that cells do not begin the next stage until the last one is finished, is a significant element of cell cycle regulation. Cell cycle checkpoints are characteristics that constitute an excellent monitoring strategy for accurate cell cycle and divisions. Cdks, associated cyclin counterparts, protein kinases, and phosphatases regulate cell growth and division from one stage to another. The cell cycle is controlled by the temporal activation of Cdks, which is governed by cyclin partner interaction, phosphorylation by particular protein kinases, and de-phosphorylation by Cdc25 family phosphatases. In response to DNA damage, a cell's DNA repair reaction is a cascade of signaling pathways that leads to checkpoint engagement, regulates, the repairing mechanism in DNA, cell cycle alterations, and apoptosis. Numerous biochemical structures, as well as processes that detect damage in DNA, are ATM and ATR, which induce the DNA repair checkpoints",
"title": "Cell cycle checkpoints and DNA damage repair system"
},
{
"paragraph_id": 26,
"text": "The cell cycle is a sequence of activities in which cell organelles are duplicated and subsequently separated into daughter cells with precision. There are major events that happen during a cell cycle. The processes that happen in the cell cycle include cell development, replication and segregation of chromosomes. The cell cycle checkpoints are surveillance systems that keep track of the cell cycle's integrity, accuracy, and chronology. Each checkpoint serves as an alternative cell cycle endpoint, wherein the cell's parameters are examined and only when desirable characteristics are fulfilled does the cell cycle advance through the distinct steps. The cell cycle's goal is to precisely copy each organism's DNA and afterwards equally split the cell and its components between the two new cells. Four main stages occur in the eukaryotes. In G1, the cell is usually active and continues to grow rapidly, while in G2, the cell growth continues while protein molecules become ready for separation. These are not dormant times; they are when cells gain mass, integrate growth factor receptors, establish a replicated genome, and prepare for chromosome segregation. DNA replication is restricted to a separate Synthesis in eukaryotes, which is also known as the S-phase. During mitosis, which is also known as the M-phase, the segregation of the chromosomes occur. DNA, like every other molecule, is capable of undergoing a wide range of chemical reactions. Modifications in DNA's sequence, on the other hand, have a considerably bigger impact than modifications in other cellular constituents like RNAs or proteins because DNA acts as a permanent copy of the cell genome. When erroneous nucleotides are incorporated during DNA replication, mutations can occur. The majority of DNA damage is fixed by removing the defective bases and then re-synthesizing the excised area. On the other hand, some DNA lesions can be mended by reversing the damage, which may be a more effective method of coping with common types of DNA damage. Only a few forms of DNA damage are mended in this fashion, including pyrimidine dimers caused by ultraviolet (UV) light changed by the insertion of methyl or ethyl groups at the purine ring's O6 position.",
"title": "Cell cycle checkpoints and DNA damage repair system"
},
{
"paragraph_id": 27,
"text": "Mitochondria are commonly referred to as the cell's \"powerhouses\" because of their capacity to effectively produce ATP which is essential to maintain cellular homeostasis and metabolism. Moreover, researchers have gained a better knowledge of mitochondria's significance in cell biology because of the discovery of cell signaling pathways by mitochondria which are crucial platforms for cell function regulation such as apoptosis. Its physiological adaptability is strongly linked to the cell mitochondrial channel's ongoing reconfiguration through a range of mechanisms known as mitochondrial membrane dynamics, which include endomembrane fusion and fragmentation (separation) as well as ultrastructural membrane remodeling. As a result, mitochondrial dynamics regulate and frequently choreograph not only metabolic but also complicated cell signaling processes such as cell pluripotent stem cells, proliferation, maturation, aging, and mortality. Mutually, post-translational alterations of mitochondrial apparatus and the development of transmembrane contact sites among mitochondria and other structures, which both have the potential to link signals from diverse routes that affect mitochondrial membrane dynamics substantially, Mitochondria are wrapped by two membranes: an inner mitochondrial membrane (IMM) and an outer mitochondrial membrane (OMM), each with a distinctive function and structure, which parallels their dual role as cellular powerhouses and signaling organelles. The inner mitochondrial membrane divides the mitochondrial lumen into two parts: the inner border membrane, which runs parallel to the OMM, and the cristae, which are deeply twisted, multinucleated invaginations that give room for surface area enlargement and house the mitochondrial respiration apparatus. The outer mitochondrial membrane, on the other hand, is soft and permeable. It, therefore, acts as a foundation for cell signaling pathways to congregate, be deciphered, and be transported into mitochondria. Furthermore, the OMM connects to other cellular organelles, such as the endoplasmic reticulum (ER), lysosomes, endosomes, and the plasma membrane. Mitochondria play a wide range of roles in cell biology, which is reflected in their morphological diversity. Ever since the beginning of the mitochondrial study, it has been well documented that mitochondria can have a variety of forms, with both their general and ultra-structural morphology varying greatly among cells, during the cell cycle, and in response to metabolic or cellular cues. Mitochondria can exist as independent organelles or as part of larger systems; they can also be unequally distributed in the cytosol through regulated mitochondrial transport and placement to meet the cell's localized energy requirements. Mitochondrial dynamics refers to the adaptive and variable aspect of mitochondria, including their shape and subcellular distribution.",
"title": "Mitochondrial membrane dynamics"
},
{
"paragraph_id": 28,
"text": "Autophagy is a self-degradative mechanism that regulates energy sources during growth and reaction to dietary stress. Autophagy also cleans up after itself, clearing aggregated proteins, cleaning damaged structures including mitochondria and endoplasmic reticulum and eradicating intracellular infections. Additionally, autophagy has antiviral and antibacterial roles within the cell, and it is involved at the beginning of distinctive and adaptive immune responses to viral and bacterial contamination. Some viruses include virulence proteins that prevent autophagy, while others utilize autophagy elements for intracellular development or cellular splitting. Macro autophagy, micro autophagy, and chaperon-mediated autophagy are the three basic types of autophagy. When macro autophagy is triggered, an exclusion membrane incorporates a section of the cytoplasm, generating the autophagosome, a distinctive double-membraned organelle. The autophagosome then joins the lysosome to create an autolysosome, with lysosomal enzymes degrading the components. In micro autophagy, the lysosome or vacuole engulfs a piece of the cytoplasm by invaginating or protruding the lysosomal membrane to enclose the cytosol or organelles. The chaperone-mediated autophagy (CMA) protein quality assurance by digesting oxidized and altered proteins under stressful circumstances and supplying amino acids through protein denaturation. Autophagy is the primary intrinsic degradative system for peptides, fats, carbohydrates, and other cellular structures. In both physiologic and stressful situations, this cellular progression is vital for upholding the correct cellular balance. Autophagy instability leads to a variety of illness symptoms, including inflammation, biochemical disturbances, aging, and neurodegenerative, due to its involvement in controlling cell integrity. The modification of the autophagy-lysosomal networks is a typical hallmark of many neurological and muscular illnesses. As a result, autophagy has been identified as a potential strategy for the prevention and treatment of various disorders. Many of these disorders are prevented or improved by consuming polyphenol in the meal. As a result, natural compounds with the ability to modify the autophagy mechanism are seen as a potential therapeutic option. The creation of the double membrane (phagophore), which would be known as nucleation, is the first step in macro-autophagy. The phagophore approach indicates dysregulated polypeptides or defective organelles that come from the cell membrane, Golgi apparatus, endoplasmic reticulum, and mitochondria. With the conclusion of the autophagocyte, the phagophore's enlargement comes to an end. The auto-phagosome combines with the lysosomal vesicles to formulate an auto-lysosome that degrades the encapsulated substances, referred to as phagocytosis.",
"title": "Autophagy"
}
] | Cell biology is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. Cell biology is the study of the structural and functional units of cells. Cell biology encompasses both prokaryotic and eukaryotic cells and has many subtopics which may include the study of cell metabolism, cell communication, cell cycle, biochemistry, and cell composition. The study of cells is performed using several microscopy techniques, cell culture, and cell fractionation. These have allowed for and are currently being used for discoveries and research pertaining to how cells function, ultimately giving insight into understanding larger organisms. Knowing the components of cells and how cells work is fundamental to all biological sciences while also being essential for research in biomedical fields such as cancer, and other diseases. Research in cell biology is interconnected to other fields such as genetics, molecular genetics, molecular biology, medical microbiology, immunology, and cytochemistry. | 2001-10-26T15:00:55Z | 2023-12-29T03:37:33Z | [
"Template:Use dmy dates",
"Template:Further",
"Template:Div col",
"Template:Gallery",
"Template:ISBN",
"Template:H2O-nl",
"Template:Cite book",
"Template:Cite web",
"Template:Citation",
"Template:Wikibooks",
"Template:Branches of biology",
"Template:Biology nav",
"Template:Div col end",
"Template:Portal",
"Template:Cite EB1911",
"Template:Cite journal",
"Template:Cellular structures",
"Template:Reflist",
"Template:Doi",
"Template:Library resources box",
"Template:Curlie",
"Template:Short description",
"Template:Issn",
"Template:About",
"Template:Main",
"Template:NCBI-scienceprimer",
"Template:Authority control",
"Template:TopicTOC-Biology",
"Template:Commonscatinline",
"Template:Molecular and cellular biology",
"Template:Branches of chemistry"
] | https://en.wikipedia.org/wiki/Cell_biology |
6,340 | Canadian English | Canadian English (CanE, CE, en-CA) encompasses the varieties of English used in Canada, while Standard Canadian English is the Canadian standard variety of English. According to the 2016 census, English was the first language of 19.4 million Canadians or 58.1% of the total population; the remainder spoke French (20.8%) or other languages (21.1%). In Quebec, 7.5% of the population are anglophone, as most of Quebec's residents are native speakers of Quebec French.
Phonologically, Standard Canadian and General American English may be grouped together as North American English, emphasizing the two varieties' identical phonemic inventories, whose realizations, however, differ. While Canadian English tends to be closer to American English in most regards, it does possess elements from British English and some uniquely Canadian characteristics. The precise influence of American English, British English and other sources on Canadian English varieties has been the ongoing focus of systematic studies since the 1950s.
Canadians and Americans themselves often have trouble differentiating their own two accents, particularly when someone speaks with an urban Standard Canadian English accent because it sounds similar to Western American English. There is also evidence that Standard Canadian English and Western American English have been undergoing a similar vowel shift since the 1980s. Canadian English varies little from Central Canada to British Columbia. But, some noticeably different accents can be found in the Atlantic provinces, most especially in Newfoundland with Newfoundland English. Accent differences can sometimes be heard between those who live in urban centres versus those living in rural settings.
In the early 20th century, western Canada was largely populated by farmers from Central and Eastern Europe who were not anglophones. At the time, most anglophones there were re-settlers from Ontario or Quebec who had British, Irish and/or Loyalist ancestry. Throughout the 20th century, the prairies underwent anglicization and linguistic homogenization through education and exposure to Canadian and American media.
The term "Canadian English" is first attested in a speech by the Reverend A. Constable Geikie in an address to the Canadian Institute in 1857 (see DCHP-1 Online, s.v. "Canadian English", Avis et al., 1967). Geikie, a Scottish-born Canadian, reflected the Anglocentric attitude that would be prevalent in Canada for the next hundred years when he referred to the language as "a corrupt dialect", in comparison with what he considered the proper English spoken by immigrants from Britain.
One of the earliest influences on Canadian English was the French language, which was brought to Canada by the French colonists in the 17th century. French words and expressions were adopted into Canadian English, especially in the areas of cuisine, politics, and social life. For example, words like beavertail, and toque are uniquely Canadian French terms that have become part of the Canadian English lexicon.
An important influence on Canadian English was British English, which was brought to Canada by British settlers in the 18th and 19th centuries. Canadian English borrowed many words and expressions from British English, including words like lorry, flat, and lift. However, Canadian English also developed its own unique vocabulary, including words like tuque, chesterfield, and double-double.
American English also had a significant impact on Canadian English, especially in the 20th century as a result of increased cultural and economic ties between the two countries. American English terms like gasoline, truck, and apartment are commonly used in Canadian English, and some Canadian English speakers have adopted American English pronunciation and grammar.
The growth of Canadian media, including television, film, and literature, has also played a role in shaping Canadian English. Chambers (1998) notes that Canadian media has helped to create new words and expressions that reflect Canadian culture and values. Canadian institutions, such as the CBC and the Canadian Oxford Dictionary, have also played a role in promoting and defining Canadian English.
In addition to these influences, Canadian English has also been shaped by Indigenous languages. Indigenous words like moose, toboggan, and moccasin have become part of the Canadian English lexicon.
Canadian English is the product of five waves of immigration and settlement over a period of more than two centuries. The first large wave of permanent English-speaking settlement in Canada, and linguistically the most important, was the influx of Loyalists fleeing the American Revolution, chiefly from the Mid-Atlantic States—as such, Canadian English is believed by some scholars to have derived from northern American English. Canadian English has been developing features of its own since the early 19th century. The second wave from Britain and Ireland was encouraged to settle in Canada after the War of 1812 by the governors of Canada, who were worried about American dominance and influence among its citizens. Further waves of immigration from around the globe peaking in 1910, 1960, and at the present time had a lesser influence, but they did make Canada a multicultural country, ready to accept linguistic change from around the world during the current period of globalization.
The languages of Aboriginal peoples in Canada started to influence European languages used in Canada even before widespread settlement took place, and the French of Lower Canada provided vocabulary, with words such as tuque and portage, to the English of Upper Canada.
Overall, the history of Canadian English is a reflection of the country's diverse linguistic and cultural heritage. While Canadian English has borrowed many words and expressions from other languages, it has also developed its own unique vocabulary and pronunciation that reflects the country's distinct identity.
Studies on earlier forms of English in Canada are rare, yet connections with other work to historical linguistics can be forged. An overview of diachronic work on Canadian English, or diachronically relevant work, is Dollinger (2012, updated to 2017). Until the 2000s, basically all commentators on the history of CanE have argued from the "language-external" history, i.e. social and political history. An exception has been in the area of lexis, where Avis et al.'s 1967 Dictionary of Canadianisms on Historical Principles offered real-time historical data through its quotations. Starting in the 2000s, historical linguists have started to study earlier Canadian English with historical linguistic data. DCHP-1 is now available in open access. Most notably, Dollinger (2008) pioneered the historical corpus linguistic approach for English in Canada with CONTE (Corpus of Early Ontario English, 1776–1849) and offers a developmental scenario for 18th- and 19th-century Ontario. In 2015, Reuter confirmed the scenario laid out in Dollinger (2008), using a 19th-century newspaper corpus from Ontario.
Historically, Canadian English included a class-based sociolect known as Canadian dainty. Treated as a marker of upper-class prestige in the 19th and early 20th centuries, Canadian dainty was marked by the use of some features of British English pronunciation, resulting in an accent similar, but not identical, to the Mid-Atlantic accent known in the United States. This accent faded in prominence following World War II, when it became stigmatized as pretentious, and is now almost never heard in modern Canadian life outside of archival recordings used in film, television or radio documentaries.
Canadian spelling of the English language combines British and American conventions, the two dominant varieties, and adds some domestic idiosyncrasies. For many words, American and British spelling are both acceptable. Spelling in Canadian English co-varies with regional and social variables, somewhat more so, perhaps, than in the two dominant varieties of English, yet general trends have emerged since the 1970s.
Canadian spelling conventions can be partly explained by Canada's trade history. For instance, the British spelling of the word cheque probably relates to Canada's once-important ties to British financial institutions. Canada's automobile industry, on the other hand, has been dominated by American firms from its inception, explaining why Canadians use the American spelling of tire (hence, "Canadian Tire") and American terminology for automobiles and their parts (for example, truck instead of lorry, gasoline instead of petrol, trunk instead of boot).
Canada's political history has also had an influence on Canadian spelling. Canada's first prime minister, John A. Macdonald, once advised the Governor General of Canada to issue an order-in-council directing that government papers be written in the British style.
A contemporary reference for formal Canadian spelling is the spelling used for Hansard transcripts of the Parliament of Canada (see The Canadian Style in Further reading below). Many Canadian editors, though, use the Canadian Oxford Dictionary, often along with the chapter on spelling in Editing Canadian English, and, where necessary (depending on context), one or more other references. (See Further reading below.)
Throughout part of the 20th century, some Canadian newspapers adopted American spellings, for example, color as opposed to the British-based colour. Some of the most substantial historical spelling data can be found in Dollinger (2010) and Grue (2013). The use of such spellings was the long-standing practice of the Canadian Press perhaps since that news agency's inception, but visibly the norm prior to World War II. The practice of dropping the letter u in such words was also considered a labour-saving technique during the early days of printing in which movable type was set manually. Canadian newspapers also received much of their international content from American press agencies, therefore it was much easier for editorial staff to leave the spellings from the wire services as provided.
In the 1990s, Canadian newspapers began to adopt the British spelling variants such as -our endings, notably with The Globe and Mail changing its spelling policy in October 1990. Other Canadian newspapers adopted similar changes later that decade, such as the Southam newspaper chain's conversion in September 1998. The Toronto Star adopted this new spelling policy in September 1997 after that publication's ombudsman discounted the issue earlier in 1997. The Star had always avoided using recognized Canadian spelling, citing the Gage Canadian Dictionary in their defence. Controversy around this issue was frequent. When the Gage Dictionary finally adopted standard Canadian spelling, the Star followed suit. Some publishers, e.g. Maclean's, continue to prefer American spellings.
The first series of dictionaries of Canadian English was published by Gage Ltd. The Beginner's Dictionary (1962), the Intermediate Dictionary (1964) and, finally, the Senior Dictionary (1967) were milestones in Canadian English lexicography. In November 1967 A Dictionary of Canadianisms on Historical Principles (DCHP) was published and completed the first edition of Gage's Dictionary of Canadian English Series. The DCHP documents the historical development of Canadian English words that can be classified as "Canadianisms". It therefore includes words such as mukluk, Canuck, and bluff, but does not list common core words such as desk, table or car. Many secondary schools in Canada use the graded dictionaries. The dictionaries have regularly been updated since: the Senior Dictionary, edited by Robert John Gregg, was renamed Gage Canadian Dictionary. Its fifth edition was printed beginning in 1997. Gage was acquired by Thomson Nelson around 2003. The latest editions were published in 2009 by HarperCollins. On 17 March 2017 a second edition of DCHP, the online Dictionary of Canadianisms on Historical Principles 2 (DCHP-2), was published. DCHP-2 incorporates the c. 10 000 lexemes from DCHP-1 and adds c. 1 300 novel meanings or 1 002 lexemes to the documented lexicon of Canadian English.
In 1997, the ITP Nelson Dictionary of the Canadian English Language was another product, but has not been updated since.
In 1998, Oxford University Press produced a Canadian English dictionary, after five years of lexicographical research, entitled The Oxford Canadian Dictionary. A second edition, retitled The Canadian Oxford Dictionary, was published in 2004. Just as the older dictionaries it includes uniquely Canadian words and words borrowed from other languages, and surveyed spellings, such as whether colour or color was the more popular choice in common use. Paperback and concise versions (2005, 2006), with minor updates, are available.
In terms of the major sound systems (phonologies) of English around the world, Canadian English aligns most closely to American English, though it does also possess certain elements of British English. Both Canadian and American English are grouped together under a common North American English sound system; the mainstream Canadian accent ("Standard Canadian") is often compared to the similar and largely overlapping "General American" accent, an accent widely spoken throughout the United States and perceived there as being relatively lacking in any noticeable regional features.
Western Canada (British Columbia, Alberta, Saskatchewan, Manitoba) shows the largest dialect diversity. Northern Canada is, according to William Labov, a dialect region in formation where a homogeneous English dialect has not yet formed. A homogeneous dialect exists in Western and Central Canada, a situation that is similar to that of the Western United States. Labov identifies an "Inland Canada" region that concentrates all of the defining features of the dialect centred on the Prairies (a region in Western Canada that mainly includes Alberta, Saskatchewan, and Manitoba and is known for its grasslands and plains), with more variable patterns including the metropolitan areas of Vancouver and Toronto. This dialect forms a dialect continuum with Western US English, sharply differentiated from Inland Northern US English of the central and eastern Great Lakes region.
Canadian English raises the diphthong onsets of diphthongs /aɪ/ and /aʊ/ to [ə] or [ʌ] before voiceless segments.
Standard Canadian English is socially defined. Standard Canadian English is spoken by those who live in urban Canada, in a middle-class job (or one of their parents holds such employment), who are second generation or later (born and raised in Canada) and speak English as (one of their) dominant language(s) (Dollinger 2019a, adapted from Chambers 1998). It is the variety spoken, in Chambers' (1998: 252) definition, by Anglophone or multilingual residents, who are second generation or later (i.e. born in Canada) and who live in urban settings. Applying this definition, c. 36% of the Canadian population speak Standard Canadian English in the 2006 population, with 38% in the 2011 census.
The literature has for a long time conflated the notions of Standard Canadian English (StCE) and regional variation. While some regional dialects are close to Standard Canadian English, they are not identical to it. To the untrained ear, for instance, a BC middle-class speaker from a rural setting may seemingly be speaking Standard Canadian English, but, given Chambers' definition, such a person, because of the rural provenance, would not be included in the accepted definition (see the previous section). The Atlas of North American English, while being the best source for US regional variation, is not a good source for Canadian regional variation, as its analysis is based on only 33 Canadian speakers. Boberg's (2005, 2008) studies offer the best data for the delimitation of dialect zones. The results for vocabulary and phonetics overlap to a great extent, which has allowed the proposal of dialect zones. Dollinger and Clarke distinguish between:
First Nations and Inuit from Northern Canada speak a version of Canadian English influenced by the phonology of their first languages. European Canadians in these regions are relatively recent arrivals, and have not produced a dialect that is distinct from southern Canadian English.
Overall, First Nations Canada English dialects rest between language loss and language revitalization. British Columbia has the greatest linguistic diversity, as it is home to about half of the Indigenous languages spoken in Canada. Most of the languages spoken in the province are endangered due to the small number of speakers. To some extent, the dialects reflect the historical contexts where English has been a major colonizing language. The dialects are also a result of the late stages of depidginization and decreolization, which resulted in linguistic markers of Indigenous identity and solidarity. These dialects are observed to have developed a lingua francas due to the contact between English and Indigenous populations, and eventually, the various dialects began to converge with standard English.
Certain First Nations English have also shown to have phonological standard Canadian English, thus resulting in a more distinct dialect formation. Plains Cree, for instance, is a language that has less phonological contrasts compared to standard Canadian English. Plains Cree has no voicing contrast. The stops /p/, /t/, and /k/ are mostly voiceless and unaspirated, though they may vary in other phonetic environments from voiceless to voiced. Plains Cree also does not have the liquids or fricatives found in the standard form. Dene Suline, on the other hand, has more phonological contrasts, resulting from the use of features not seen in the standard form. The language has 39 phonemic consonants and a higher proportion of glottalized consonants.
Many in the Maritime provinces – Nova Scotia, New Brunswick and Prince Edward Island – have an accent that sounds more like Scottish English and, in some places, Irish English than General American. Outside of major communities, dialects can vary markedly from community to community, as well as from province to province, reflecting ethnic origin as well as a past in which there were few roads and many communities, with some isolated villages. Into the 1980s, residents of villages in northern Nova Scotia could identify themselves by dialects and accents distinctive to their village. The dialects of Prince Edward Island are often considered the most distinct grouping.
The phonology of Maritimer English has some unique features:
As with many other distinct dialects, vowels are a marker of Halifax English as a distinctive variant of Canadian English. Typically, Canadian dialects have a merger of the low back vowels in palm, lot, thought and cloth. The merged vowel in question is usually /ɑ/ or sometimes the rounded variant /ɒ/. Meanwhile, in Halifax, the vowel is raised and rounded. For example, body; popped; and gone. In the homophones, caught-cot and stalk-stock, the rounding in the merged vowel is also much more pronounced here than in other Canadian varieties. The Canadian Shift is also not as evident in the traditional dialect. Instead, the front vowels are raised. For example, the vowel in had is raised to [hæed]; and camera is raised to [kæmra].
Although it has not been studied extensively, the speech of Cape Breton specifically seems to bear many similarities with the nearby island of Newfoundland, which is often why Westerners can have a hard time differentiating the two accents. For instance, they both use the fronting of the low back vowel. These similarities can be attributed to geographic proximity, the fact that about one-quarter of the Cape Breton population descends from Irish immigrants - many of whom arrived via Newfoundland - and the Scottish and Irish influences on both provinces. The speech of Cape Breton can almost be seen as a continuum between the two extremes of the Halifax variant and the Newfoundland variant. In addition, there is heavy influence of standard varieties of Canadian English on Cape Breton English, especially in the diphthongization of the goat and goose vowels and the frequent use of Canadian raising.
Compared to the commonly spoken English dominating neighbouring provinces, Newfoundland English is famously distinct in its dialects and accents. Newfoundland English differs in vowel pronunciation, morphology, syntax, and preservation of archaic adverbial-intensifiers. The dialect varies markedly from community to community, as well as from region to region. Its distinctiveness partly results from a European settlement history that dates back centuries, which explains Newfoundland's most notable linguistic regions: an Irish-settled area in the southeast (the southern Avalon Peninsula) and an English-settled area in the southwest.
A well-known phonetic feature many Newfoundland speakers possess is the kit-dress merger. The mid lax /ɛ/ here is raised to the high lax stressed /ɪ/, particularly before oral stops and nasals, so consequently "pen" is pronounced more like "pin".
Another phonetic feature more unique to Newfoundland English is TH-stopping. Here, the voiceless dental fricative /θ/ in words like myth and width are pronounced more like t or the voiced dental fricative /ð/ in words like the and these. TH-stopping is more common for /ð/, especially in unstressed function words (e.g. that, those, their, etc.).
Canadian raising is quite strong throughout the province of Ontario, except within the Ottawa Valley. The introduction of Canadian raising to Canada can be attributed to the Scottish and Irish immigrants who arrived in the 18th and 19th centuries.The origins of Canadian raising to Scotland and revealed that the Scottish dialects spoken by these immigrants had a probable impact on its development. This feature impacts the pronunciation of the /aɪ/ sound in "right" and the /aʊ/ sound in "lout". Canadian Raising indicates a scenario where the start of the diphthong is nearer to the destination of the glide before voiceless consonants than before voiced consonants. The Canadian Shift is also a common vowel shift found in Ontario. The retraction of /æ/ was found to be more advanced for women in Ontario than for people from the Prairies or Atlantic Canada and men.
In the southern part of Southwestern Ontario (roughly in the line south from Sarnia to St. Catharines), despite the existence of many characteristics of West/Central Canadian English, many speakers, especially those under 30, speak a dialect influenced by the Inland Northern American English dialect (in part due to proximity to cities like Detroit and Buffalo, New York) though there are minor differences such as Canadian raising (e.g. "ice" vs "my").
The north and northwestern parts of Southwestern Ontario, the area consisting of the Counties of Huron, Bruce, Grey, and Perth, referred to as the "Queen's Bush" in the 19th century, did not experience communication with the dialects of the southern part of Southwestern Ontario and Central Ontario until the early 20th century. Thus, a strong accent similar to Central Ontarian is heard, yet many different phrasings exist. It is typical in the area to drop phonetic sounds to make shorter contractions, such as: prolly (probably), goin' (going), and "Wuts goin' on tonight? D'ya wanna do sumthin'?" It is particularly strong in the County of Bruce, so much that it is commonly referred to as being the Bruce Cownian (Bruce Countian) accent. Also, /ɜr/ merge with /ɛr/ to [ɛɹ], with "were" sounding more like "wear".
Residents of the Golden Horseshoe (including the Greater Toronto Area) are known to merge the second /t/ with the /n/ in Toronto, pronouncing the name variously as [təˈɹɒɾ̃o] or [ˈtɹɒɾ̃o]. This is not unique to Toronto; Atlanta is often pronounced "Atlanna" by residents. Sometimes /ð/ is elided altogether, resulting in "Do you want this one er'iss one?" The word southern is often pronounced with [aʊ]. In the area north of the Regional Municipality of York and south of Parry Sound, notably among those who were born in the surrounding communities, the cutting down of syllables and consonants often heard, e.g. "probably" is reduced to "prolly" or "probly" when used as a response. In Greater Toronto, the diphthong tends to be fronted (as a result the word about is pronounced as [əˈbɛʊt]). The Greater Toronto Area is linguistically diverse, with 43 percent of its people having a mother tongue other than English. As a result Toronto English has distinctly more variability than Inland Canada.
In Eastern Ontario, Canadian raising is not as strong as it is in the rest of the province. In Prescott and Russell, parts of Stormont-Dundas-Glengarry and Eastern Ottawa, French accents are often mixed with English ones due to the high Franco-Ontarian population there. In Lanark County, Western Ottawa and Leeds-Grenville and the rest of Stormont-Dundas-Glengarry, the accent spoken is nearly identical to that spoken in Central Ontario and the Quinte area.
A linguistic enclave has also formed in the Ottawa Valley, heavily influenced by original Scottish, Irish, and German settlers, and existing along the Ontario-Quebec boundary, which has its own distinct accent known as the Ottawa Valley twang (or brogue). Phonetically, the Ottawa Valley twang is characterized by the lack of Canadian raising as well as the cot–caught merger, two common elements of mainstream Canadian English. This accent is quite rare in the region today.
English is a minority language in Quebec (with French the majority), but has many speakers in Montreal, the Eastern Townships and in the Gatineau-Ottawa region. A person whose mother tongue is English and who still speaks English is called an Anglophone, versus a Francophone, or French speaker.
Many people in Montreal distinguish between words like marry versus merry and parish versus perish, which are homophones to most other speakers of Canadian English. Quebec Anglophones generally pronounce French street names in Montreal as French words. Pie IX Boulevard is pronounced as in French: not as "pie nine" but as /ˌpiːˈnʊf/ pee-NUUF (compare French /pi.nœf/). On the other hand, Anglophones pronounce the final d as in Bernard and Bouchard; the word Montreal is pronounced as an English word and Rue Lambert-Closse is known as Clossy Street (vs French /klɔs/). In the city of Montreal, especially in some of the western suburbs like Côte-St-Luc and Hampstead, there is a strong Jewish influence in the English spoken in those areas. A large wave of Jewish immigration from Eastern Europe and the former Soviet Union before and after World War II is also evident today. Their English has a strong Yiddish influence, and there are some similarities to English spoken in New York. Words used mainly in Quebec and especially in Montreal are: stage for "apprenticeship" or "internship", copybook for a notebook, dépanneur or dep for a convenience store, and guichet for an ABM/ATM. It is also common for Anglophones, particularly those of Greek or Italian descent, to use translated French words instead of common English equivalents such as "open" and "close" for "on" and "off" or "Open the lights, please" for "Turn on the lights, please".
Western Canadian English describes the English spoken in the four most western provinces—British Columbia, Alberta, Saskatchewan, and Manitoba. British Columbia, in particular is a sub-zone on the lexical level. Phonetically, Western Canadian English has much more /æɡ/ raising and much less /æn/ than further east, and Canadian raised /aʊ/ is further back.
British Columbia English shares dialect features with both Standard Canadian English and the American Pacific Northwest English. In Vancouver, speakers exhibit more vowel retraction of /æ/ before nasals than people from Toronto, and this retraction may become a regional marker of West Coast English. /ɛɡ/ raising (found in words such as beg, leg, and peg) and /æɡ/ raising (found words such as bag, lag and rag), a prominent feature in Northwestern American speakers, is also found in Vancouver speakers, causing "beg" to sound like the first syllable of "bagel" and "bag" to be similar. In the past, the ANAE reported that Vancouverites' participation in the Canadian raising of /aɪ/ was questionable, but nowadays they tend to raise both /aɪ/ and /aʊ/. The "o" in such words as holy, goal, load, know, etc. is pronounced as a close-mid back rounded vowel, [o], but not as rounded as in the Prairies where there are strong Scandinavian, Slavic and German influences, which can lend to a more stereotypical "Canadian" accent.
Finally, there is also the /t/ sound which according to Gregg (2016), "with many [Vancouver] speakers [is] intrusive between /l/ or /n/ and /s/ in words like sense /sɛnts/, Wilson /wɪltsən/ [and] also /'ɒltsoʊ/ ".
English in Saskatchewan has its pool of phonetic features shared with other provinces used by certain demographics. For instance, it has the consonant variables /ntV/ and /VtV/, the latter being a common feature of North American English and is defined as the intervoicing of /t/ between vowels. Meanwhile, /ntV/ "frequently occurs in words such as "centre" and "twenty" where /t/ follows the alveolar nasal /n/ and precedes an unstressed vowel". According to Nylvek (1992), both variables of /t/ are generally more often used by younger male over older female speakers.
There are a handful of syntactical practices unique to Canadian English. When writing, Canadians may start a sentence with As well, in the sense of "in addition"; this construction is a Canadianism.
North American English prefers have got to have to denote possession or obligation (as in I've got a car vs. I have a car); Canadian English differs from American English in tending to eschew plain got (I got a car), which is a common third option in informal US English.
The grammatical construction "be done something" means roughly "have/has finished something". For example, "I am done my homework" and "The dog is done dinner" are genuine sentences in this dialect, respectively meaning "I have finished my homework" and "The dog has finished dinner". Another example, "Let's start after you're done all the coffee", means "Let's start after you've finished all the coffee". This is not exactly the same as the standard construction "to be done with something", since "She is done the computer" can only mean "She is done with the computer" in one sense: "She has finished (building) the computer".
Date and time notation in Canadian English is a mixture of British and American practices. The date can be written in the form of either "July 1, 2017" or "1 July 2017"; the latter is common in more formal writing and bilingual contexts. The Government of Canada only recommends writing all-numeric dates in the form of YYYY-MM-DD (e.g. 2017-07-01), following ISO 8601. Nonetheless, the traditional DD/MM/YY and MM/DD/YY systems remain in everyday use, which can be interpreted in multiple ways: 01/07/17 can mean either 1 July 2017 or 7 January 2017. Private members' bills have repeatedly attempted to clarify the situation. In business communication and filing systems the YYMMDD is used to assist in automatic ordering of electronic files.
The government also recommends use of the 24-hour clock, which is widely used in contexts such as transportation schedules, parking meters, and data transmission. Many speakers of English use the 12-hour clock in everyday speech, even when reading from a 24-hour display, similar to the use of the 24-hour clock in the United Kingdom.
Where Canadian English shares vocabulary with other English dialects, it tends to share most with American English, but also has many non-American terms distinctively shared instead with Britain. British and American terms also can coexist in Canadian English to various extents, sometimes with new nuances in meaning; a classic example is holiday (British) often used interchangeably with vacation (American), though, in Canadian speech, the latter can more narrowly mean a trip elsewhere and the former can mean general time off work. In addition, the vocabulary of Canadian English also features some words that are seldom (if ever) found elsewhere. A good resource for these and other words is A Dictionary of Canadianisms on Historical Principles, which is currently being revised at the University of British Columbia in Vancouver, British Columbia. The Canadian public appears to take interest in unique "Canadianisms": words that are distinctively characteristic of Canadian English—though perhaps not exclusive to Canada; there is some disagreement about the extent to which "Canadianism" means a term actually unique to Canada, with such an understanding possibly overstated by the popular media. As a member of the Commonwealth of Nations, Canada shares many items of institutional terminology and professional designations with the countries of the former British Empire—for example, constable, for a police officer of the lowest rank, and chartered accountant.
While Canadian English has vocabulary that distinguishes it from other varieties of English across the world, there is significant regional variation in its lexis within Canada as well. A balanced cross-continental sample of 1800 Canadians and 360 Americans the Canada and the USA is the result of Boberg's North American Regional Vocabulary Survey (NARVS), a questionnaire employed by Boberg from 1999-2007 that sought out lexical items that vary regionally within Canada. Six regions were identified in the NARVS data collection: The West, which includes British Columbia and the Prairies; Ontario; Quebec, which represents data from Montreal mostly; New Brunswick and Nova Scotia; Prince Edward Island; and Newfoundland. Many regional differences in the lexis are item-specific. For example, one of these items has to do with the nationally enjoyed meal of pizza, and more specifically, the term used to refer to a pizza that features all available toppings. While Atlantic Canada refers to this order as ‘the works,’ the majority term used from eastern Ontario to the West Coast is deluxe, and terms such as 'all-dressed' and 'everything-on-it' are used in Quebec and Toronto, respectively. Other examples include the regionally varied usage of running shoes/runners/sneakers to describe athletic shoes, and notebook/scribbler/cahier to describe any type of plain note-pad. Despite the regional variation of vocabulary items within Canada, the lexis of Canadian English still maintains greater commonality between its own regions than it does with American English or British English.
Quebec recognizes French as its primary language. As a result, English has no official status in Québec and is not used often in the public sphere. Although, in more metropolitan area such as Montréal or Québec City, it is not uncommon to see English media in public, such as in advertisements and store-fronts. Also, the provincial government must officially be referred to as the "Gouvernement du Québec", regardless of the language being by the speaker. While the lexical catalog of Quebec English contains items influenced or borrowed by French, the influence of the dominant French language on Quebec English is marginal. The francophone dominance in Quebec makes the province a linguistic anomaly within Canada, where English maintains a negligible role in government and public domains. The French influence on Quebec English operates through five distinct processes, as identified by Charles Boberg: elective direct lexical transfer of non-English words (e.g., garderie for daycare), imposed direct lexical transfer of non-English words. for example, SAQ for Société des alcools du Québec, loan translation/calques such as 'all-dressed' for the French equivalent 'toute garnie'. Semantic shifts of existing English words, like 'magasin' for 'store', in addition to syntactic influences; e.g, "we're living here three years" instead of the English "we've been living here for three years". Although Quebec English differs from other Canadian regional lexes due to its special contact with French, it still shares some similarities with the lexis of other Canadian regions. For instance, the use of lexical items such as all-dressed has been successfully transferred to most other Canadian regional lexes.
Southern Ontario was initially settled by white Protestants, with the late 19th century witnessing the migration of white Protestant settlers from Ontario to western Canada following the suppression of the Métis opposition. This migration facilitated the transplantation of the Ontario accent and the emergence of a homogeneous Canadian English dialect. Distinctive to Ontario are Canadianisms such as concession roads, which refer to roads that transect a township, dew-worm, which refers to an earthworm, and fire-reel, which refers to a fire truck. Walter S. Avis identified several linguistic features characteristic of Ontarians, including their preference for the word vacation, rather than holiday—which is considered more British English—and sack over paper bag. While there may be numerous such lexical differences in the speech of provincial and national borderers, Avis asserts that these are relatively minor compared to the linguistic features held in common. Furthermore, Avis suggests that the difference between American English and Ontario English is relatively small near the border due to their close proximity. The historical settlement patterns of southern Ontario, coupled with linguistic research, indicate the existence of distinctively Ontarian lexical items. However, Ontario maintains greater similarities with other Canadian regions than it does with the neighbouring American English and its regional variations.
Northern Ontario English has several distinct qualities stemming from its large Franco-Ontarian population. As a result several French and English words are used interchangeably. A number of phrases and expressions may also be found in Northern Ontario that are not present in the rest of the province, such as the use of camp for a summer home where Southern Ontario speakers would idiomatically use cottage.
In the mid to late 90s, certain words from Jamaican Patois, Arabic and Somali were incorporated into the local variety of English by Toronto youth, especially in immigrant communities, thus giving rise to Toronto slang. These examples included words such as mandem, styll, wallahi, wasteman, and yute.
The Prairies, consisting of Manitoba, Saskatchewan, and Alberta, have their own lexical features. The linguistic legacy from the settlement patterns in these regions, along with the Indigenous communities, specifically the large Métis population in Saskatchewan and Manitoba also carry certain linguistic traits inherited from the French, Aboriginal and Celtic forebears. The linguistic features brought by Ukrainian, German, and Mennonite populations in the Saskatchewan Valley of Saskatchewan and Red River Valley of Manitoba have also influenced the lexis of the Prairies. Some terms are derived from these groups and some are formed within the region by locals throughout time. An example of the former is the high-profile variable bunnyhug, a term for a hooded sweatshirt in Saskatchewan. As discussed in The Dictionary of Canadianisms on Historical Principles, bunnyhug is purposely and commonly used by young Saskatchewan speakers to indicate a sense of provincial identity, and is referred to as a Saskatchewanism. It should be further noted that it is assumed based on circumstantial evidence that teenagers played a crucial and special role in the spread and adoption of the term bunnyhug for hooded sweatshirts. Across Saskatchewan, Alberta, and Manitoba there are other terms consistent in or throughout the 3 provinces. Biffed is a term for falling, such as "John biffed it over there". Pickerel is Manitoba's official fish, also known as Walleye. Play structure is used to describe a playground for children consisting of monkey bars, slides, etc.
Canada's Atlantic provinces were the first part of North America to be discovered by Europeans. The Atlantic provinces, historically and collectively called the Maritimes, consist of New Brunswick, Nova Scotia, Prince Edward Island. Newfoundland and Labrador, which is not part of the Maritimes, is also part of Atlantic Canada. The historical immigrants from Europe have shaped cultures and lexical catalogs across the regions of Atlantic Canada that reflect British, Scottish, Gaelic, and French customs. The vernacular variations of English spoken in the Atlantic region of Canada. Newfoundland and Labrador English (NLE) possesses unique vocabulary compared to standard Canadian English. The Dictionary of Newfoundland English covers the vocabulary common to Newfoundlanders, such as Newfoundland "screech rum", a Newfoundland-specific brand of rum; mummering, referring to a Christmas tradition; and gut-foundered, meaning starving or fastened. Nova Scotia also is home to its own vocabulary. The term "Sobeys bag", used to refer to a plastic grocery bag, originates from the Nova Scotian grocery store chain Sobeys. Similarly, Prince Edward Island has its own vocabulary and dictionary. For example, angishore refers to a fisherman who is too lazy to fish and likely is a lexical item originating from Irish Gaelic settlers in Newfoundland. Sarah Sawler, a writer from Halifax, highlights terms that are common to Maritimes, such as dooryard for front yard, owly for when someone is angry or irritable, and biff for throw.
The term college, which refers to post-secondary education in general in the US, refers in Canada to either a post-secondary technical or vocational institution, or to one of the colleges that exist as federated schools within some Canadian universities. Most often, a college is a community college, not a university. It may also refer to a CEGEP in Quebec. In Canada, college student might denote someone obtaining a diploma in business management, an equivalent of this would be an associate degree in the United States. In contrast, university student is the term for someone earning a bachelor's degree, typically at a post-secondary university institution. Hence, the term going to college in Canada does not have the same meaning as going to university, unless the speaker or context clarifies the specific level of post-secondary education that is meant.
Within the public school system the chief administrator of a school is generally "the principal", as in the United States, but the term is not used preceding their name, i.e., "Principal Smith". The assistant to the principal is not titled as "assistant principal", but rather as "vice-principal", although the former is not unknown. This usage is identical to that in Northern Ireland.
Canadian universities publish calendars or schedules, not catalogs as in the US. Canadian students write or take exams (in the US, students generally "take" exams while teachers "write" them); they rarely sit them (standard British usage). Those who supervise students during an exam are sometimes called invigilators as in Britain, or sometimes proctors as in the US; usage may depend on the region or even the individual institution.
Successive years of school are usually referred to as grade one, grade two, and so on. In Quebec, Francophone speakers will often say primary one, primary two as a direct translation from the French, and so on; while Anglophones will say grade one, grade two. These terms are comparable with the American first grade, second grade (which is used in Canada, yet is rare), English/Welsh Year 1, Year 2, Scottish/Northern Irish Primary 1, Primary 2 or P1, P2, and Southern Irish First Class, Second Class and so on. The year of school before grade 1 is usually called "Kindergarten", with the exception of Nova Scotia, where it is called "grade primary". In addition, children younger than the public school start age may attend 'pre-primary', although this is a newer addition to the Nova Scotian public-school system, and is not used frequently elsewhere.
In parts of the US, the four years of high school are termed the freshman, sophomore, junior, and senior years (terms also used for college years); in Canada, the specific levels are used instead, such as "grade nine" in lieu of freshman. As for higher education, only the term freshman (often reduced to frosh) has some currency in Canada. Moreover, some Canadian public-school systems have adolescents start high-school in 'Grade 10' or, the sophomore year, although, this can depend on the province and even vary within a school-district. The American usages "sophomore", "junior" and "senior" are not used in Canadian university terminology, or in speech. The specific high-school grades and university years are therefore stated and individualized; for example, 'Sarah is starting Grade 10 this year', which Americans would state as 'Sarah is going to be a sophomore this year'. Similarly in the post-secondary education context, 'Francois is in second year of university' rather than the Americanism 'Francois is a sophomore in university'.
Canadian students use the term marks (more common in England) or grades (more common in the US) to refer to their results. Usage is mixed, although marks more commonly refer to a single score whereas grades often refers to the cumulative score in that class.
Unlike in the United States, use of metric units within a majority of industries is standard in Canada, as a result of the partial national adoption of the metric system during the mid-to-late 1970s that was eventually stalled; this has spawned some colloquial usages such as klick for kilometre.
Nonetheless, US units are still used in many situations. Imperial volumes are also used, albeit rarely—although many Canadians and Americans mistakenly conflate the measurement systems despite their slight differences from each other (e.g. US and metric cups are 237ml and 250ml, respectively).
For example, most English Canadians state their weight and height in pounds and feet/inches, respectively. This is also the case for many Quebec Francophones. Distances while playing golf are always marked and discussed in yards, though official scorecards may also show metres. Temperatures for cooking or pools are often given in Fahrenheit, while the weather is given in Celsius. Directions in the Prairie provinces are sometimes given using miles, because the country roads generally follow the mile-based grid of the Dominion Land Survey. Motor vehicle speed limits are measured in kilometres per hour.
Canadians measure property, both residential and commercial, floor areas are in square feet or square metres, property is in square feet, square metres, acres or hectares. Fuel efficiency is more often discussed in the metric L/100 km than miles per US gallon. The Letter paper size of 8.5 inches × 11 inches is used instead of the international and metric equivalent A4 size of 210 mm × 297 mm. Beer cans are 355 mL (12 US oz), while beer bottles are typically 341 mL (12 Imperial oz), and draft beer is sold in various units; US or Imperial oz, US or Imperial pint, or occasionally mL.
Building materials are used in soft conversions of imperial sizes, but often purchased in relation to the imperial sizes. For example, 8-inch concrete masonry units can be referred to as an 8-inch CMU or 190 CMU. The actual material used in the US and Canada is the same.
Expressway may also refer to a limited-access road that has control of access but has at-grade junctions, railway crossings (for example, the Harbour Expressway in Thunder Bay.) Sometimes the term Parkway is also used (for example, the Hanlon Parkway in Guelph). In Saskatchewan, the term 'grid road' is used to refer to minor highways or rural roads, usually gravel, referring to the 'grid' upon which they were originally designed. In Quebec, freeways and expressways are called autoroutes.
In Alberta, the generic Trail is often used to describe a freeway, expressway or major urban street (for example, Deerfoot Trail, Macleod Trail or Crowchild Trail in Calgary, Yellowhead Trail, Victoria Trail or Mark Messier/St.Albert Trail in Edmonton). The British term motorway is not used. The American terms turnpike and tollway for a toll road are not common. The term throughway or thruway was used for first tolled limited-access highways (for example, the Deas Island Throughway, now Highway 99, from Vancouver, BC, to Blaine, Washington, USA or the Saint John Throughway (Highway 1) in Saint John, NB), but this term is not common anymore. In everyday speech, when a particular roadway is not being specified, the term highway is generally or exclusively used.
Lawyers in all parts of Canada, except Quebec, which has its own civil law system, are called "barristers and solicitors" because any lawyer licensed in any of the common law provinces and territories must pass bar exams for, and is permitted to engage in, both types of legal practice in contrast to other common-law jurisdictions such as England, Wales and Ireland where the two are traditionally separated (i.e., Canada has a fused legal profession). The words lawyer and counsel (not counsellor) predominate in everyday contexts; the word attorney refers to any personal representative. Canadian lawyers generally do not refer to themselves as "attorneys", a term that is common in the United States.
The equivalent of an American district attorney, meaning the barrister representing the state in criminal proceedings, is called a crown attorney (in Ontario), crown counsel (in British Columbia), crown prosecutor or the crown, on account of Canada's status as a constitutional monarchy in which the Crown is the locus of state power.
The words advocate and notary – two distinct professions in Quebec civil law – are used to refer to that province's approximate equivalents of barrister and solicitor, respectively. It is not uncommon for English-speaking advocates in Quebec to refer to themselves in English as "barrister(s) and solicitor(s)", as most advocates chiefly perform what would traditionally be known as "solicitor's work", while only a minority of advocates actually appear in court. In Canada's common law provinces and territories, the word notary means strictly a notary public.
Within the Canadian legal community itself, the word solicitor is often used to refer to any Canadian lawyer in general (much like the way the word attorney is used in the United States to refer to any American lawyer in general). Despite the conceptual distinction between barrister and solicitor, Canadian court documents would contain a phrase such as "John Smith, solicitor for the Plaintiff" even though "John Smith" may well himself be the barrister who argues the case in court. In a letter introducing him/herself to an opposing lawyer, a Canadian lawyer normally writes something like "I am the solicitor" for Mr. Tom Jones."
The word litigator is also used by lawyers to refer to a fellow lawyer who specializes in lawsuits even though the more traditional word barrister is still employed to denote the same specialization.
Judges of Canada's superior courts, which exist at the provincial and territorial levels, are traditionally addressed as "My Lord" or "My Lady". This varies by jurisdiction, and some superior court judges prefer the titles "Mister Justice" or "Madam Justice" to "Lordship".
Masters are addressed as "Mr. Master" or simply "Sir." In British Columbia, masters are addressed as "Your Honour."
Judges of provincial or inferior courts are traditionally referred to in person as "Your Honour". Judges of the Supreme Court of Canada and of the federal-level courts prefer the use of "Mister/Madam (Chief) Justice". Justices of The Peace are addressed as "Your Worship". "Your Honour" is also the correct form of address for a Lieutenant Governor.
A serious crime is called an indictable offence, while a less-serious crime is called a summary conviction offence. The older words felony and misdemeanour, which are still used in the United States, are not used in Canada's current Criminal Code (R.S.C. 1985, c. C-46) or by today's Canadian legal system. As noted throughout the Criminal Code, a person accused of a crime is called the accused and not the defendant, a term used instead in civil lawsuits.
In Canada, visible minority refers to a non-aboriginal person or group visibly not one of the majority race in a given population. The term comes from the Canadian Employment Equity Act, which defines such people as "persons, other than Aboriginal people, who are non-Caucasian in race or non-white in colour." The term is used as a demographic category by Statistics Canada. The qualifier "visible" is used to distinguish such minorities from the "invisible" minorities determined by language (English vs. French) and certain distinctions in religion (Catholics vs. Protestants).
A county in British Columbia means only a regional jurisdiction of the courts and justice system and is not otherwise connected to governance as with counties in other provinces and in the United States. The rough equivalent to "county" as used elsewhere is a "Regional District".
Distinctive Canadianisms are:
Terms common in Canada, Britain and Ireland but less frequent or nonexistent in the United States are:
The following are more or less distinctively Canadian:
The following are common in Canada, but not in the United States or the United Kingdom.
One of the most distinctive Canadian phrases is the spoken interrogation or tag eh. The only usage of eh exclusive to Canada, according to the Canadian Oxford Dictionary, is for "ascertaining the comprehension, continued interest, agreement, etc., of the person or persons addressed" as in, "It's four kilometres away, eh, so I have to go by bike." In that case, eh? is used to confirm the attention of the listener and to invite a supportive noise such as mm or oh or okay. This usage is also common in Queensland, Australia and New Zealand. Other uses of eh – for instance, in place of huh? or what? meaning "please repeat or say again" – are also found in parts of the British Isles and Australia. It is common in Northern/Central Ontario, the Maritimes and the Prairie provinces. The word eh is used quite frequently in the North Central dialect, so a Canadian accent is often perceived in people from North Dakota, Michigan, Minnesota, and Wisconsin.
A rubber in the US and Canada is slang for a condom. In Canada, it sometimes means an eraser (as in the United Kingdom and Ireland).
The word bum can refer either to the buttocks (as in Britain), or to a homeless person (as in the US). The "buttocks" sense does not have the indecent character it retains in British use, as it and "butt" are commonly used as a polite or childish euphemism for ruder words such as arse (commonly used in Atlantic Canada and among older people in Ontario and to the west) or ass, or mitiss (used in the Prairie Provinces, especially in northern and central Saskatchewan; probably originally a Cree loanword). Older Canadians may see "bum" as more polite than "butt", which before the 1980s was often considered rude.
Similarly the word pissed can refer either to being drunk (as in Britain), or being angry (as in the US), though anger is more often said as pissed off, while piss drunk or pissed up is said to describe inebriation (though piss drunk is sometimes also used in the US, especially in the northern states).
The term Canuck simply means Canadian in its demonymic form, and, as a term used even by Canadians themselves, it is not considered derogatory. (In the 19th century and early 20th century it tended to refer to French-Canadians.) The only Canadian-built version of the popular World War I-era American Curtiss JN-4 Jenny training biplane aircraft, the JN-4C, 1,260 of which were built, got the "Canuck" nickname; so did another aircraft, the Fleet Model 80, built from the mid-1940s until the late 1950s. The nickname Janey Canuck was used by Anglophone women's rights writer Emily Murphy in the 1920s and the Johnny Canuck comic book character of the 1940s. Throughout the 1970s, Canada's winning World Cup men's downhill ski team was called the "Crazy Canucks" for their fearlessness on the slopes. It is also the name of the Vancouver Canucks, the National Hockey League team of Vancouver, British Columbia.
The term hoser, popularized by Bob & Doug McKenzie, typically refers to an uncouth, beer-swilling male and is a euphemism for "loser" coming from the earlier days of hockey played on an outdoor rink and the losing team would have to hose down the ice after the game so it froze smooth. Bob & Doug also popularized the use of Beauty, eh, another western slang term which may be used to describe something as being of interest or note or deserving approval.
A Newf or Newfie is someone from Newfoundland and Labrador; sometimes considered derogatory. In Newfoundland, the term Mainlander refers to any Canadian (sometimes American, occasionally Labradorian) not from the island of Newfoundland. Mainlander is also occasionally used derogatorily.
In the Maritimes, a Caper or "Cape Bretoner" is someone from Cape Breton Island, a Bluenoser is someone with a thick, usually southern Nova Scotia accent or as a general term for a Nova Scotian (including Cape Bretoners), while an Islander is someone from Prince Edward Island (the same term is used in British Columbia for people from Vancouver Island, or the numerous islands along it). A Haligonian refers to someone from the city of Halifax.
Cape Bretoners and Newfies (from Newfoundland and Labrador) often have similar slang. "Barmp" is often used as the sound a car horn makes, example: "He cut me off so I barmped the horn at him". When saying "B'y", while sounds like the traditional farewell, it is a syncopated shortening of the word "boy", referring to a person, example: "How's it goin, b'y?". Another slang that is commonly used is "doohickey" which means an object, example: "Pass me that doohickey over there". When an individual uses the word "biffed", they mean that they threw something. Example: "I got frustrated so I biffed it across the room".
In language studies, there are three basic types of data collection: introspection, elicitation, and observation. Introspection relies on the idea that native speakers are the best judges of sentence structure and can provide valuable data, but it can be limiting because it only requires one native speaker. Elicitation requires more effort, but is a widespread technique used to gather linguistic structures by asking informants how they say certain things in their language. Observation is considered the "gold standard" by many linguists because it involves collecting utterances after the fact and systematically analyzing them. This can be done through corpora, which are collections of spoken or written text, but most corpus material today consists of written texts since they are more easily accessible. Variationist sociolinguistics aim to elicit data that is as natural and informal as possible, using techniques such as sociolinguistic interviews to gather different speech styles.
The use of written questionnaires (WQs) in dialectology were once popular for surveying language use, but fell out of favor before being re-examined in recent years. While they were once considered less effective than other survey methods, scholars have started to recognize their potential in social dialectology and variation studies. In the early 1950s, McDavid noted the value of using a lexical WQ for the Linguistic Atlas of Scotland, but later, Chambers and Trudgill stated that WQs were no longer the primary method of data-gathering. However, within the past 15 years, WQs have experienced renewed interest in social dialectology and variation studies. WQs can provide linguistic information about behavior and can be used for self-reporting or community reporting.
Scholars have used five types of questionnaires in sociolinguistics. Dollinger suggests a three-tiered WQ question typology. The first tier covers questions about regional language variation and social language variation. The second tier covers language perception and attitudes, while the third tier deals with acceptability judgments of grammaticality. The questions can be classified by subject area, type of reporting, and the type of information sought. This classification can help scholars better utilize WQs and understand their potential.
Written surveys are commonly used in dialectology as regional differences are less socially sensitive. However, they can still be used in sociolinguistics if handled properly. A survey's advantage is its quantitative approach since it is capable of collecting large amounts of data within a relatively short time. This would allow researchers to have a more robust statistical analysis and reliable or accurate conclusions about regional or social patterns. Despite its advantages, there are still disadvantages using surveys for a research study particularly in capturing natural speech patterns due to the observer's paradox. Through its unique format, surveys containing direct questions about language may not provide sufficient enough information on how often or in what social or linguistic contexts people use distinct language features. Therefore, by relying on systematic observations, local participants may adhere to perceived norms or expectations. While written surveys can provide valuable information about sociolinguistic variables in Canadian English, data gathered from surveys or questionnaires should not be perceived as equivalent to data gathered from the usage of actual speech. William Labov, a linguist, suggests that in order to solve this problem is to change the style of approach of surveys. Therefore, he suggests that researchers design sociolinguistic interviews that manipulate attention to speech. By comparing the speech among research participants when they are being directly questioned about language with their speech when talking about their personal experience, Labov could observe how the usage of language within different contexts or environments. This newly suggested approach allowed Labov to capture the "vernacular" which is the casual style of speech that people use within a day-to-day basis when they are not being observed.
Canadian English dialectology examines Canadian English through the use of written surveys due to the vastness of the country and the difficulties of conducting face-to-face interviews on a nationwide level. The historical overview of written surveys in Canadian-English dialectology includes Avis's study of speech differences among the Ontario-United States borders through the use of questionnaires. Another example is the Survey of Canadian English directed by Scargill. A more recent example would be Nylvek's survey of Saskatchewan English and Chambers' trans-Canada dialect questionnaires.
An attitude study in the late 1970s revealed a positive attitude toward Canadian linguistic features. Features include front vowel merger before/r/, low-back vowel merger, Canadian Raising, and Canadian lexical items. Still, the sample group in British Columbia showed a preference for UK and US English.
This attitude sees a change years later. A survey about attitudes towards CE was conducted with a diverse sample group in Vancouver, BC, in 2009. Among 429 Vancouverites, 81.1% believe there is a Canadian way of speaking English, 72.9% can tell CanE speakers from American English speakers, 69.1% consider CanE a part of their Canadian identity, and 74.1% think CanE should be taught in schools. Due to the unavailability of free and easy-to-access CanE dictionaries, many Canadian opt for other non-Canadian English dictionaries today. Historically, American, British, and Irish texts are used in Canadian schools for the most part; even though Canadian reference work was written and became available in the 1960s, they were never preferred as teaching material.
A preference change can be seen at the end of higher education in Canada. At the University of Toronto's Graduate English department, "Canadian English" and a "consistent spelling" are officially "the standard for all Ph.D. dissertations," with the Canadian Oxford English Dictionary as the official guideline. However, there is no mention of which grammar guide was to be followed because there was never a solid standard developed for spelling and grammar.
In 2011, just under 21.5 million Canadians, representing 65% of the population, spoke English most of the time at home, while 58% declared it their mother language. English is the major language everywhere in Canada except Quebec, and most Canadians (85%) can speak English. While English is not the preferred language in Quebec, 36.1% of the Québécois can speak English. Nationally, Francophones are five times more likely to speak English than Anglophones are to speak French – 44% and 9% respectively. Only 3.2% of Canada's English-speaking population resides in Quebec—mostly in Montreal.
A study conducted in 2002 inquired Canadians from Ontario and Alberta about the "pleasantness" and "correctness" of different varieties of Canadian English based on province. Albertans and Ontarians all seem to rate their English and BC English in the top three. However, both hold a low opinion of Quebec English. Unlike the assumption that Toronto or Ontario English would be the most prestigious considering these regions are the most economically robust, BC had the best public opinion regarding pleasantness and correctness among the participants.
Jaan Lilles argues in an essay for English Today that there is no variety of "Canadian English". According to Lilles, a former M.A. student, Canadian English is simply not a "useful fiction". He goes on to argue that too often supposedly unique features of Canadian speakers, such as certain lexical terms such as muskeg are artificially exaggerated to distinguish Canadian speech primarily from that found in the United States. Lilles was heavily critiqued in the next issue of English Today by lexicographer Fraser Sutherland and others. According to Stefan Dollinger, Lilles' paper "is not a paper based on any data or other new information but more of a pamphlet – so much so that it should not have been published without a public critique". He continues: "The paper is insightful for different reasons: it is a powerful testimony of personal anecdote and opinion [...]. As an opinion piece, it offers a good debating case." As a linguistic account, however, it "essentializes a prior state, before Canada was an independent political entity".
Dollinger, Stefan (2015). The Written Questionnaire in Social Dialectology: History, Theory, Practice. Archived 18 May 2016 at the Wayback Machine Amsterdam/Philadelphia: Benjamins. The book's examples are exclusive taken from Canadian English and represent one of the more extensive collections of variables for Canadian English.
The dictionary definition of Canadian English at Wiktionary | [
{
"paragraph_id": 0,
"text": "Canadian English (CanE, CE, en-CA) encompasses the varieties of English used in Canada, while Standard Canadian English is the Canadian standard variety of English. According to the 2016 census, English was the first language of 19.4 million Canadians or 58.1% of the total population; the remainder spoke French (20.8%) or other languages (21.1%). In Quebec, 7.5% of the population are anglophone, as most of Quebec's residents are native speakers of Quebec French.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Phonologically, Standard Canadian and General American English may be grouped together as North American English, emphasizing the two varieties' identical phonemic inventories, whose realizations, however, differ. While Canadian English tends to be closer to American English in most regards, it does possess elements from British English and some uniquely Canadian characteristics. The precise influence of American English, British English and other sources on Canadian English varieties has been the ongoing focus of systematic studies since the 1950s.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Canadians and Americans themselves often have trouble differentiating their own two accents, particularly when someone speaks with an urban Standard Canadian English accent because it sounds similar to Western American English. There is also evidence that Standard Canadian English and Western American English have been undergoing a similar vowel shift since the 1980s. Canadian English varies little from Central Canada to British Columbia. But, some noticeably different accents can be found in the Atlantic provinces, most especially in Newfoundland with Newfoundland English. Accent differences can sometimes be heard between those who live in urban centres versus those living in rural settings.",
"title": ""
},
{
"paragraph_id": 3,
"text": "In the early 20th century, western Canada was largely populated by farmers from Central and Eastern Europe who were not anglophones. At the time, most anglophones there were re-settlers from Ontario or Quebec who had British, Irish and/or Loyalist ancestry. Throughout the 20th century, the prairies underwent anglicization and linguistic homogenization through education and exposure to Canadian and American media.",
"title": ""
},
{
"paragraph_id": 4,
"text": "The term \"Canadian English\" is first attested in a speech by the Reverend A. Constable Geikie in an address to the Canadian Institute in 1857 (see DCHP-1 Online, s.v. \"Canadian English\", Avis et al., 1967). Geikie, a Scottish-born Canadian, reflected the Anglocentric attitude that would be prevalent in Canada for the next hundred years when he referred to the language as \"a corrupt dialect\", in comparison with what he considered the proper English spoken by immigrants from Britain.",
"title": "History"
},
{
"paragraph_id": 5,
"text": "One of the earliest influences on Canadian English was the French language, which was brought to Canada by the French colonists in the 17th century. French words and expressions were adopted into Canadian English, especially in the areas of cuisine, politics, and social life. For example, words like beavertail, and toque are uniquely Canadian French terms that have become part of the Canadian English lexicon.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "An important influence on Canadian English was British English, which was brought to Canada by British settlers in the 18th and 19th centuries. Canadian English borrowed many words and expressions from British English, including words like lorry, flat, and lift. However, Canadian English also developed its own unique vocabulary, including words like tuque, chesterfield, and double-double.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "American English also had a significant impact on Canadian English, especially in the 20th century as a result of increased cultural and economic ties between the two countries. American English terms like gasoline, truck, and apartment are commonly used in Canadian English, and some Canadian English speakers have adopted American English pronunciation and grammar.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "The growth of Canadian media, including television, film, and literature, has also played a role in shaping Canadian English. Chambers (1998) notes that Canadian media has helped to create new words and expressions that reflect Canadian culture and values. Canadian institutions, such as the CBC and the Canadian Oxford Dictionary, have also played a role in promoting and defining Canadian English.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "In addition to these influences, Canadian English has also been shaped by Indigenous languages. Indigenous words like moose, toboggan, and moccasin have become part of the Canadian English lexicon.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "Canadian English is the product of five waves of immigration and settlement over a period of more than two centuries. The first large wave of permanent English-speaking settlement in Canada, and linguistically the most important, was the influx of Loyalists fleeing the American Revolution, chiefly from the Mid-Atlantic States—as such, Canadian English is believed by some scholars to have derived from northern American English. Canadian English has been developing features of its own since the early 19th century. The second wave from Britain and Ireland was encouraged to settle in Canada after the War of 1812 by the governors of Canada, who were worried about American dominance and influence among its citizens. Further waves of immigration from around the globe peaking in 1910, 1960, and at the present time had a lesser influence, but they did make Canada a multicultural country, ready to accept linguistic change from around the world during the current period of globalization.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "The languages of Aboriginal peoples in Canada started to influence European languages used in Canada even before widespread settlement took place, and the French of Lower Canada provided vocabulary, with words such as tuque and portage, to the English of Upper Canada.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "Overall, the history of Canadian English is a reflection of the country's diverse linguistic and cultural heritage. While Canadian English has borrowed many words and expressions from other languages, it has also developed its own unique vocabulary and pronunciation that reflects the country's distinct identity.",
"title": "History"
},
{
"paragraph_id": 13,
"text": "Studies on earlier forms of English in Canada are rare, yet connections with other work to historical linguistics can be forged. An overview of diachronic work on Canadian English, or diachronically relevant work, is Dollinger (2012, updated to 2017). Until the 2000s, basically all commentators on the history of CanE have argued from the \"language-external\" history, i.e. social and political history. An exception has been in the area of lexis, where Avis et al.'s 1967 Dictionary of Canadianisms on Historical Principles offered real-time historical data through its quotations. Starting in the 2000s, historical linguists have started to study earlier Canadian English with historical linguistic data. DCHP-1 is now available in open access. Most notably, Dollinger (2008) pioneered the historical corpus linguistic approach for English in Canada with CONTE (Corpus of Early Ontario English, 1776–1849) and offers a developmental scenario for 18th- and 19th-century Ontario. In 2015, Reuter confirmed the scenario laid out in Dollinger (2008), using a 19th-century newspaper corpus from Ontario.",
"title": "Historical linguistics"
},
{
"paragraph_id": 14,
"text": "Historically, Canadian English included a class-based sociolect known as Canadian dainty. Treated as a marker of upper-class prestige in the 19th and early 20th centuries, Canadian dainty was marked by the use of some features of British English pronunciation, resulting in an accent similar, but not identical, to the Mid-Atlantic accent known in the United States. This accent faded in prominence following World War II, when it became stigmatized as pretentious, and is now almost never heard in modern Canadian life outside of archival recordings used in film, television or radio documentaries.",
"title": "Historical linguistics"
},
{
"paragraph_id": 15,
"text": "Canadian spelling of the English language combines British and American conventions, the two dominant varieties, and adds some domestic idiosyncrasies. For many words, American and British spelling are both acceptable. Spelling in Canadian English co-varies with regional and social variables, somewhat more so, perhaps, than in the two dominant varieties of English, yet general trends have emerged since the 1970s.",
"title": "Spelling"
},
{
"paragraph_id": 16,
"text": "Canadian spelling conventions can be partly explained by Canada's trade history. For instance, the British spelling of the word cheque probably relates to Canada's once-important ties to British financial institutions. Canada's automobile industry, on the other hand, has been dominated by American firms from its inception, explaining why Canadians use the American spelling of tire (hence, \"Canadian Tire\") and American terminology for automobiles and their parts (for example, truck instead of lorry, gasoline instead of petrol, trunk instead of boot).",
"title": "Spelling"
},
{
"paragraph_id": 17,
"text": "Canada's political history has also had an influence on Canadian spelling. Canada's first prime minister, John A. Macdonald, once advised the Governor General of Canada to issue an order-in-council directing that government papers be written in the British style.",
"title": "Spelling"
},
{
"paragraph_id": 18,
"text": "A contemporary reference for formal Canadian spelling is the spelling used for Hansard transcripts of the Parliament of Canada (see The Canadian Style in Further reading below). Many Canadian editors, though, use the Canadian Oxford Dictionary, often along with the chapter on spelling in Editing Canadian English, and, where necessary (depending on context), one or more other references. (See Further reading below.)",
"title": "Spelling"
},
{
"paragraph_id": 19,
"text": "Throughout part of the 20th century, some Canadian newspapers adopted American spellings, for example, color as opposed to the British-based colour. Some of the most substantial historical spelling data can be found in Dollinger (2010) and Grue (2013). The use of such spellings was the long-standing practice of the Canadian Press perhaps since that news agency's inception, but visibly the norm prior to World War II. The practice of dropping the letter u in such words was also considered a labour-saving technique during the early days of printing in which movable type was set manually. Canadian newspapers also received much of their international content from American press agencies, therefore it was much easier for editorial staff to leave the spellings from the wire services as provided.",
"title": "Spelling"
},
{
"paragraph_id": 20,
"text": "In the 1990s, Canadian newspapers began to adopt the British spelling variants such as -our endings, notably with The Globe and Mail changing its spelling policy in October 1990. Other Canadian newspapers adopted similar changes later that decade, such as the Southam newspaper chain's conversion in September 1998. The Toronto Star adopted this new spelling policy in September 1997 after that publication's ombudsman discounted the issue earlier in 1997. The Star had always avoided using recognized Canadian spelling, citing the Gage Canadian Dictionary in their defence. Controversy around this issue was frequent. When the Gage Dictionary finally adopted standard Canadian spelling, the Star followed suit. Some publishers, e.g. Maclean's, continue to prefer American spellings.",
"title": "Spelling"
},
{
"paragraph_id": 21,
"text": "The first series of dictionaries of Canadian English was published by Gage Ltd. The Beginner's Dictionary (1962), the Intermediate Dictionary (1964) and, finally, the Senior Dictionary (1967) were milestones in Canadian English lexicography. In November 1967 A Dictionary of Canadianisms on Historical Principles (DCHP) was published and completed the first edition of Gage's Dictionary of Canadian English Series. The DCHP documents the historical development of Canadian English words that can be classified as \"Canadianisms\". It therefore includes words such as mukluk, Canuck, and bluff, but does not list common core words such as desk, table or car. Many secondary schools in Canada use the graded dictionaries. The dictionaries have regularly been updated since: the Senior Dictionary, edited by Robert John Gregg, was renamed Gage Canadian Dictionary. Its fifth edition was printed beginning in 1997. Gage was acquired by Thomson Nelson around 2003. The latest editions were published in 2009 by HarperCollins. On 17 March 2017 a second edition of DCHP, the online Dictionary of Canadianisms on Historical Principles 2 (DCHP-2), was published. DCHP-2 incorporates the c. 10 000 lexemes from DCHP-1 and adds c. 1 300 novel meanings or 1 002 lexemes to the documented lexicon of Canadian English.",
"title": "Dictionaries"
},
{
"paragraph_id": 22,
"text": "In 1997, the ITP Nelson Dictionary of the Canadian English Language was another product, but has not been updated since.",
"title": "Dictionaries"
},
{
"paragraph_id": 23,
"text": "In 1998, Oxford University Press produced a Canadian English dictionary, after five years of lexicographical research, entitled The Oxford Canadian Dictionary. A second edition, retitled The Canadian Oxford Dictionary, was published in 2004. Just as the older dictionaries it includes uniquely Canadian words and words borrowed from other languages, and surveyed spellings, such as whether colour or color was the more popular choice in common use. Paperback and concise versions (2005, 2006), with minor updates, are available.",
"title": "Dictionaries"
},
{
"paragraph_id": 24,
"text": "In terms of the major sound systems (phonologies) of English around the world, Canadian English aligns most closely to American English, though it does also possess certain elements of British English. Both Canadian and American English are grouped together under a common North American English sound system; the mainstream Canadian accent (\"Standard Canadian\") is often compared to the similar and largely overlapping \"General American\" accent, an accent widely spoken throughout the United States and perceived there as being relatively lacking in any noticeable regional features.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 25,
"text": "Western Canada (British Columbia, Alberta, Saskatchewan, Manitoba) shows the largest dialect diversity. Northern Canada is, according to William Labov, a dialect region in formation where a homogeneous English dialect has not yet formed. A homogeneous dialect exists in Western and Central Canada, a situation that is similar to that of the Western United States. Labov identifies an \"Inland Canada\" region that concentrates all of the defining features of the dialect centred on the Prairies (a region in Western Canada that mainly includes Alberta, Saskatchewan, and Manitoba and is known for its grasslands and plains), with more variable patterns including the metropolitan areas of Vancouver and Toronto. This dialect forms a dialect continuum with Western US English, sharply differentiated from Inland Northern US English of the central and eastern Great Lakes region.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 26,
"text": "Canadian English raises the diphthong onsets of diphthongs /aɪ/ and /aʊ/ to [ə] or [ʌ] before voiceless segments.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 27,
"text": "Standard Canadian English is socially defined. Standard Canadian English is spoken by those who live in urban Canada, in a middle-class job (or one of their parents holds such employment), who are second generation or later (born and raised in Canada) and speak English as (one of their) dominant language(s) (Dollinger 2019a, adapted from Chambers 1998). It is the variety spoken, in Chambers' (1998: 252) definition, by Anglophone or multilingual residents, who are second generation or later (i.e. born in Canada) and who live in urban settings. Applying this definition, c. 36% of the Canadian population speak Standard Canadian English in the 2006 population, with 38% in the 2011 census.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 28,
"text": "The literature has for a long time conflated the notions of Standard Canadian English (StCE) and regional variation. While some regional dialects are close to Standard Canadian English, they are not identical to it. To the untrained ear, for instance, a BC middle-class speaker from a rural setting may seemingly be speaking Standard Canadian English, but, given Chambers' definition, such a person, because of the rural provenance, would not be included in the accepted definition (see the previous section). The Atlas of North American English, while being the best source for US regional variation, is not a good source for Canadian regional variation, as its analysis is based on only 33 Canadian speakers. Boberg's (2005, 2008) studies offer the best data for the delimitation of dialect zones. The results for vocabulary and phonetics overlap to a great extent, which has allowed the proposal of dialect zones. Dollinger and Clarke distinguish between:",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 29,
"text": "First Nations and Inuit from Northern Canada speak a version of Canadian English influenced by the phonology of their first languages. European Canadians in these regions are relatively recent arrivals, and have not produced a dialect that is distinct from southern Canadian English.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 30,
"text": "Overall, First Nations Canada English dialects rest between language loss and language revitalization. British Columbia has the greatest linguistic diversity, as it is home to about half of the Indigenous languages spoken in Canada. Most of the languages spoken in the province are endangered due to the small number of speakers. To some extent, the dialects reflect the historical contexts where English has been a major colonizing language. The dialects are also a result of the late stages of depidginization and decreolization, which resulted in linguistic markers of Indigenous identity and solidarity. These dialects are observed to have developed a lingua francas due to the contact between English and Indigenous populations, and eventually, the various dialects began to converge with standard English.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 31,
"text": "Certain First Nations English have also shown to have phonological standard Canadian English, thus resulting in a more distinct dialect formation. Plains Cree, for instance, is a language that has less phonological contrasts compared to standard Canadian English. Plains Cree has no voicing contrast. The stops /p/, /t/, and /k/ are mostly voiceless and unaspirated, though they may vary in other phonetic environments from voiceless to voiced. Plains Cree also does not have the liquids or fricatives found in the standard form. Dene Suline, on the other hand, has more phonological contrasts, resulting from the use of features not seen in the standard form. The language has 39 phonemic consonants and a higher proportion of glottalized consonants.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 32,
"text": "Many in the Maritime provinces – Nova Scotia, New Brunswick and Prince Edward Island – have an accent that sounds more like Scottish English and, in some places, Irish English than General American. Outside of major communities, dialects can vary markedly from community to community, as well as from province to province, reflecting ethnic origin as well as a past in which there were few roads and many communities, with some isolated villages. Into the 1980s, residents of villages in northern Nova Scotia could identify themselves by dialects and accents distinctive to their village. The dialects of Prince Edward Island are often considered the most distinct grouping.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 33,
"text": "The phonology of Maritimer English has some unique features:",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 34,
"text": "As with many other distinct dialects, vowels are a marker of Halifax English as a distinctive variant of Canadian English. Typically, Canadian dialects have a merger of the low back vowels in palm, lot, thought and cloth. The merged vowel in question is usually /ɑ/ or sometimes the rounded variant /ɒ/. Meanwhile, in Halifax, the vowel is raised and rounded. For example, body; popped; and gone. In the homophones, caught-cot and stalk-stock, the rounding in the merged vowel is also much more pronounced here than in other Canadian varieties. The Canadian Shift is also not as evident in the traditional dialect. Instead, the front vowels are raised. For example, the vowel in had is raised to [hæed]; and camera is raised to [kæmra].",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 35,
"text": "Although it has not been studied extensively, the speech of Cape Breton specifically seems to bear many similarities with the nearby island of Newfoundland, which is often why Westerners can have a hard time differentiating the two accents. For instance, they both use the fronting of the low back vowel. These similarities can be attributed to geographic proximity, the fact that about one-quarter of the Cape Breton population descends from Irish immigrants - many of whom arrived via Newfoundland - and the Scottish and Irish influences on both provinces. The speech of Cape Breton can almost be seen as a continuum between the two extremes of the Halifax variant and the Newfoundland variant. In addition, there is heavy influence of standard varieties of Canadian English on Cape Breton English, especially in the diphthongization of the goat and goose vowels and the frequent use of Canadian raising.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 36,
"text": "Compared to the commonly spoken English dominating neighbouring provinces, Newfoundland English is famously distinct in its dialects and accents. Newfoundland English differs in vowel pronunciation, morphology, syntax, and preservation of archaic adverbial-intensifiers. The dialect varies markedly from community to community, as well as from region to region. Its distinctiveness partly results from a European settlement history that dates back centuries, which explains Newfoundland's most notable linguistic regions: an Irish-settled area in the southeast (the southern Avalon Peninsula) and an English-settled area in the southwest.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 37,
"text": "A well-known phonetic feature many Newfoundland speakers possess is the kit-dress merger. The mid lax /ɛ/ here is raised to the high lax stressed /ɪ/, particularly before oral stops and nasals, so consequently \"pen\" is pronounced more like \"pin\".",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 38,
"text": "Another phonetic feature more unique to Newfoundland English is TH-stopping. Here, the voiceless dental fricative /θ/ in words like myth and width are pronounced more like t or the voiced dental fricative /ð/ in words like the and these. TH-stopping is more common for /ð/, especially in unstressed function words (e.g. that, those, their, etc.).",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 39,
"text": "Canadian raising is quite strong throughout the province of Ontario, except within the Ottawa Valley. The introduction of Canadian raising to Canada can be attributed to the Scottish and Irish immigrants who arrived in the 18th and 19th centuries.The origins of Canadian raising to Scotland and revealed that the Scottish dialects spoken by these immigrants had a probable impact on its development. This feature impacts the pronunciation of the /aɪ/ sound in \"right\" and the /aʊ/ sound in \"lout\". Canadian Raising indicates a scenario where the start of the diphthong is nearer to the destination of the glide before voiceless consonants than before voiced consonants. The Canadian Shift is also a common vowel shift found in Ontario. The retraction of /æ/ was found to be more advanced for women in Ontario than for people from the Prairies or Atlantic Canada and men.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 40,
"text": "In the southern part of Southwestern Ontario (roughly in the line south from Sarnia to St. Catharines), despite the existence of many characteristics of West/Central Canadian English, many speakers, especially those under 30, speak a dialect influenced by the Inland Northern American English dialect (in part due to proximity to cities like Detroit and Buffalo, New York) though there are minor differences such as Canadian raising (e.g. \"ice\" vs \"my\").",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 41,
"text": "The north and northwestern parts of Southwestern Ontario, the area consisting of the Counties of Huron, Bruce, Grey, and Perth, referred to as the \"Queen's Bush\" in the 19th century, did not experience communication with the dialects of the southern part of Southwestern Ontario and Central Ontario until the early 20th century. Thus, a strong accent similar to Central Ontarian is heard, yet many different phrasings exist. It is typical in the area to drop phonetic sounds to make shorter contractions, such as: prolly (probably), goin' (going), and \"Wuts goin' on tonight? D'ya wanna do sumthin'?\" It is particularly strong in the County of Bruce, so much that it is commonly referred to as being the Bruce Cownian (Bruce Countian) accent. Also, /ɜr/ merge with /ɛr/ to [ɛɹ], with \"were\" sounding more like \"wear\".",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 42,
"text": "Residents of the Golden Horseshoe (including the Greater Toronto Area) are known to merge the second /t/ with the /n/ in Toronto, pronouncing the name variously as [təˈɹɒɾ̃o] or [ˈtɹɒɾ̃o]. This is not unique to Toronto; Atlanta is often pronounced \"Atlanna\" by residents. Sometimes /ð/ is elided altogether, resulting in \"Do you want this one er'iss one?\" The word southern is often pronounced with [aʊ]. In the area north of the Regional Municipality of York and south of Parry Sound, notably among those who were born in the surrounding communities, the cutting down of syllables and consonants often heard, e.g. \"probably\" is reduced to \"prolly\" or \"probly\" when used as a response. In Greater Toronto, the diphthong tends to be fronted (as a result the word about is pronounced as [əˈbɛʊt]). The Greater Toronto Area is linguistically diverse, with 43 percent of its people having a mother tongue other than English. As a result Toronto English has distinctly more variability than Inland Canada.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 43,
"text": "In Eastern Ontario, Canadian raising is not as strong as it is in the rest of the province. In Prescott and Russell, parts of Stormont-Dundas-Glengarry and Eastern Ottawa, French accents are often mixed with English ones due to the high Franco-Ontarian population there. In Lanark County, Western Ottawa and Leeds-Grenville and the rest of Stormont-Dundas-Glengarry, the accent spoken is nearly identical to that spoken in Central Ontario and the Quinte area.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 44,
"text": "A linguistic enclave has also formed in the Ottawa Valley, heavily influenced by original Scottish, Irish, and German settlers, and existing along the Ontario-Quebec boundary, which has its own distinct accent known as the Ottawa Valley twang (or brogue). Phonetically, the Ottawa Valley twang is characterized by the lack of Canadian raising as well as the cot–caught merger, two common elements of mainstream Canadian English. This accent is quite rare in the region today.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 45,
"text": "English is a minority language in Quebec (with French the majority), but has many speakers in Montreal, the Eastern Townships and in the Gatineau-Ottawa region. A person whose mother tongue is English and who still speaks English is called an Anglophone, versus a Francophone, or French speaker.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 46,
"text": "Many people in Montreal distinguish between words like marry versus merry and parish versus perish, which are homophones to most other speakers of Canadian English. Quebec Anglophones generally pronounce French street names in Montreal as French words. Pie IX Boulevard is pronounced as in French: not as \"pie nine\" but as /ˌpiːˈnʊf/ pee-NUUF (compare French /pi.nœf/). On the other hand, Anglophones pronounce the final d as in Bernard and Bouchard; the word Montreal is pronounced as an English word and Rue Lambert-Closse is known as Clossy Street (vs French /klɔs/). In the city of Montreal, especially in some of the western suburbs like Côte-St-Luc and Hampstead, there is a strong Jewish influence in the English spoken in those areas. A large wave of Jewish immigration from Eastern Europe and the former Soviet Union before and after World War II is also evident today. Their English has a strong Yiddish influence, and there are some similarities to English spoken in New York. Words used mainly in Quebec and especially in Montreal are: stage for \"apprenticeship\" or \"internship\", copybook for a notebook, dépanneur or dep for a convenience store, and guichet for an ABM/ATM. It is also common for Anglophones, particularly those of Greek or Italian descent, to use translated French words instead of common English equivalents such as \"open\" and \"close\" for \"on\" and \"off\" or \"Open the lights, please\" for \"Turn on the lights, please\".",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 47,
"text": "Western Canadian English describes the English spoken in the four most western provinces—British Columbia, Alberta, Saskatchewan, and Manitoba. British Columbia, in particular is a sub-zone on the lexical level. Phonetically, Western Canadian English has much more /æɡ/ raising and much less /æn/ than further east, and Canadian raised /aʊ/ is further back.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 48,
"text": "British Columbia English shares dialect features with both Standard Canadian English and the American Pacific Northwest English. In Vancouver, speakers exhibit more vowel retraction of /æ/ before nasals than people from Toronto, and this retraction may become a regional marker of West Coast English. /ɛɡ/ raising (found in words such as beg, leg, and peg) and /æɡ/ raising (found words such as bag, lag and rag), a prominent feature in Northwestern American speakers, is also found in Vancouver speakers, causing \"beg\" to sound like the first syllable of \"bagel\" and \"bag\" to be similar. In the past, the ANAE reported that Vancouverites' participation in the Canadian raising of /aɪ/ was questionable, but nowadays they tend to raise both /aɪ/ and /aʊ/. The \"o\" in such words as holy, goal, load, know, etc. is pronounced as a close-mid back rounded vowel, [o], but not as rounded as in the Prairies where there are strong Scandinavian, Slavic and German influences, which can lend to a more stereotypical \"Canadian\" accent.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 49,
"text": "Finally, there is also the /t/ sound which according to Gregg (2016), \"with many [Vancouver] speakers [is] intrusive between /l/ or /n/ and /s/ in words like sense /sɛnts/, Wilson /wɪltsən/ [and] also /'ɒltsoʊ/ \".",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 50,
"text": "English in Saskatchewan has its pool of phonetic features shared with other provinces used by certain demographics. For instance, it has the consonant variables /ntV/ and /VtV/, the latter being a common feature of North American English and is defined as the intervoicing of /t/ between vowels. Meanwhile, /ntV/ \"frequently occurs in words such as \"centre\" and \"twenty\" where /t/ follows the alveolar nasal /n/ and precedes an unstressed vowel\". According to Nylvek (1992), both variables of /t/ are generally more often used by younger male over older female speakers.",
"title": "Phonology and phonetics"
},
{
"paragraph_id": 51,
"text": "There are a handful of syntactical practices unique to Canadian English. When writing, Canadians may start a sentence with As well, in the sense of \"in addition\"; this construction is a Canadianism.",
"title": "Grammar"
},
{
"paragraph_id": 52,
"text": "North American English prefers have got to have to denote possession or obligation (as in I've got a car vs. I have a car); Canadian English differs from American English in tending to eschew plain got (I got a car), which is a common third option in informal US English.",
"title": "Grammar"
},
{
"paragraph_id": 53,
"text": "The grammatical construction \"be done something\" means roughly \"have/has finished something\". For example, \"I am done my homework\" and \"The dog is done dinner\" are genuine sentences in this dialect, respectively meaning \"I have finished my homework\" and \"The dog has finished dinner\". Another example, \"Let's start after you're done all the coffee\", means \"Let's start after you've finished all the coffee\". This is not exactly the same as the standard construction \"to be done with something\", since \"She is done the computer\" can only mean \"She is done with the computer\" in one sense: \"She has finished (building) the computer\".",
"title": "Grammar"
},
{
"paragraph_id": 54,
"text": "Date and time notation in Canadian English is a mixture of British and American practices. The date can be written in the form of either \"July 1, 2017\" or \"1 July 2017\"; the latter is common in more formal writing and bilingual contexts. The Government of Canada only recommends writing all-numeric dates in the form of YYYY-MM-DD (e.g. 2017-07-01), following ISO 8601. Nonetheless, the traditional DD/MM/YY and MM/DD/YY systems remain in everyday use, which can be interpreted in multiple ways: 01/07/17 can mean either 1 July 2017 or 7 January 2017. Private members' bills have repeatedly attempted to clarify the situation. In business communication and filing systems the YYMMDD is used to assist in automatic ordering of electronic files.",
"title": "Grammar"
},
{
"paragraph_id": 55,
"text": "The government also recommends use of the 24-hour clock, which is widely used in contexts such as transportation schedules, parking meters, and data transmission. Many speakers of English use the 12-hour clock in everyday speech, even when reading from a 24-hour display, similar to the use of the 24-hour clock in the United Kingdom.",
"title": "Grammar"
},
{
"paragraph_id": 56,
"text": "Where Canadian English shares vocabulary with other English dialects, it tends to share most with American English, but also has many non-American terms distinctively shared instead with Britain. British and American terms also can coexist in Canadian English to various extents, sometimes with new nuances in meaning; a classic example is holiday (British) often used interchangeably with vacation (American), though, in Canadian speech, the latter can more narrowly mean a trip elsewhere and the former can mean general time off work. In addition, the vocabulary of Canadian English also features some words that are seldom (if ever) found elsewhere. A good resource for these and other words is A Dictionary of Canadianisms on Historical Principles, which is currently being revised at the University of British Columbia in Vancouver, British Columbia. The Canadian public appears to take interest in unique \"Canadianisms\": words that are distinctively characteristic of Canadian English—though perhaps not exclusive to Canada; there is some disagreement about the extent to which \"Canadianism\" means a term actually unique to Canada, with such an understanding possibly overstated by the popular media. As a member of the Commonwealth of Nations, Canada shares many items of institutional terminology and professional designations with the countries of the former British Empire—for example, constable, for a police officer of the lowest rank, and chartered accountant.",
"title": "Vocabulary"
},
{
"paragraph_id": 57,
"text": "While Canadian English has vocabulary that distinguishes it from other varieties of English across the world, there is significant regional variation in its lexis within Canada as well. A balanced cross-continental sample of 1800 Canadians and 360 Americans the Canada and the USA is the result of Boberg's North American Regional Vocabulary Survey (NARVS), a questionnaire employed by Boberg from 1999-2007 that sought out lexical items that vary regionally within Canada. Six regions were identified in the NARVS data collection: The West, which includes British Columbia and the Prairies; Ontario; Quebec, which represents data from Montreal mostly; New Brunswick and Nova Scotia; Prince Edward Island; and Newfoundland. Many regional differences in the lexis are item-specific. For example, one of these items has to do with the nationally enjoyed meal of pizza, and more specifically, the term used to refer to a pizza that features all available toppings. While Atlantic Canada refers to this order as ‘the works,’ the majority term used from eastern Ontario to the West Coast is deluxe, and terms such as 'all-dressed' and 'everything-on-it' are used in Quebec and Toronto, respectively. Other examples include the regionally varied usage of running shoes/runners/sneakers to describe athletic shoes, and notebook/scribbler/cahier to describe any type of plain note-pad. Despite the regional variation of vocabulary items within Canada, the lexis of Canadian English still maintains greater commonality between its own regions than it does with American English or British English.",
"title": "Vocabulary"
},
{
"paragraph_id": 58,
"text": "Quebec recognizes French as its primary language. As a result, English has no official status in Québec and is not used often in the public sphere. Although, in more metropolitan area such as Montréal or Québec City, it is not uncommon to see English media in public, such as in advertisements and store-fronts. Also, the provincial government must officially be referred to as the \"Gouvernement du Québec\", regardless of the language being by the speaker. While the lexical catalog of Quebec English contains items influenced or borrowed by French, the influence of the dominant French language on Quebec English is marginal. The francophone dominance in Quebec makes the province a linguistic anomaly within Canada, where English maintains a negligible role in government and public domains. The French influence on Quebec English operates through five distinct processes, as identified by Charles Boberg: elective direct lexical transfer of non-English words (e.g., garderie for daycare), imposed direct lexical transfer of non-English words. for example, SAQ for Société des alcools du Québec, loan translation/calques such as 'all-dressed' for the French equivalent 'toute garnie'. Semantic shifts of existing English words, like 'magasin' for 'store', in addition to syntactic influences; e.g, \"we're living here three years\" instead of the English \"we've been living here for three years\". Although Quebec English differs from other Canadian regional lexes due to its special contact with French, it still shares some similarities with the lexis of other Canadian regions. For instance, the use of lexical items such as all-dressed has been successfully transferred to most other Canadian regional lexes.",
"title": "Vocabulary"
},
{
"paragraph_id": 59,
"text": "Southern Ontario was initially settled by white Protestants, with the late 19th century witnessing the migration of white Protestant settlers from Ontario to western Canada following the suppression of the Métis opposition. This migration facilitated the transplantation of the Ontario accent and the emergence of a homogeneous Canadian English dialect. Distinctive to Ontario are Canadianisms such as concession roads, which refer to roads that transect a township, dew-worm, which refers to an earthworm, and fire-reel, which refers to a fire truck. Walter S. Avis identified several linguistic features characteristic of Ontarians, including their preference for the word vacation, rather than holiday—which is considered more British English—and sack over paper bag. While there may be numerous such lexical differences in the speech of provincial and national borderers, Avis asserts that these are relatively minor compared to the linguistic features held in common. Furthermore, Avis suggests that the difference between American English and Ontario English is relatively small near the border due to their close proximity. The historical settlement patterns of southern Ontario, coupled with linguistic research, indicate the existence of distinctively Ontarian lexical items. However, Ontario maintains greater similarities with other Canadian regions than it does with the neighbouring American English and its regional variations.",
"title": "Vocabulary"
},
{
"paragraph_id": 60,
"text": "Northern Ontario English has several distinct qualities stemming from its large Franco-Ontarian population. As a result several French and English words are used interchangeably. A number of phrases and expressions may also be found in Northern Ontario that are not present in the rest of the province, such as the use of camp for a summer home where Southern Ontario speakers would idiomatically use cottage.",
"title": "Vocabulary"
},
{
"paragraph_id": 61,
"text": "In the mid to late 90s, certain words from Jamaican Patois, Arabic and Somali were incorporated into the local variety of English by Toronto youth, especially in immigrant communities, thus giving rise to Toronto slang. These examples included words such as mandem, styll, wallahi, wasteman, and yute.",
"title": "Vocabulary"
},
{
"paragraph_id": 62,
"text": "The Prairies, consisting of Manitoba, Saskatchewan, and Alberta, have their own lexical features. The linguistic legacy from the settlement patterns in these regions, along with the Indigenous communities, specifically the large Métis population in Saskatchewan and Manitoba also carry certain linguistic traits inherited from the French, Aboriginal and Celtic forebears. The linguistic features brought by Ukrainian, German, and Mennonite populations in the Saskatchewan Valley of Saskatchewan and Red River Valley of Manitoba have also influenced the lexis of the Prairies. Some terms are derived from these groups and some are formed within the region by locals throughout time. An example of the former is the high-profile variable bunnyhug, a term for a hooded sweatshirt in Saskatchewan. As discussed in The Dictionary of Canadianisms on Historical Principles, bunnyhug is purposely and commonly used by young Saskatchewan speakers to indicate a sense of provincial identity, and is referred to as a Saskatchewanism. It should be further noted that it is assumed based on circumstantial evidence that teenagers played a crucial and special role in the spread and adoption of the term bunnyhug for hooded sweatshirts. Across Saskatchewan, Alberta, and Manitoba there are other terms consistent in or throughout the 3 provinces. Biffed is a term for falling, such as \"John biffed it over there\". Pickerel is Manitoba's official fish, also known as Walleye. Play structure is used to describe a playground for children consisting of monkey bars, slides, etc.",
"title": "Vocabulary"
},
{
"paragraph_id": 63,
"text": "Canada's Atlantic provinces were the first part of North America to be discovered by Europeans. The Atlantic provinces, historically and collectively called the Maritimes, consist of New Brunswick, Nova Scotia, Prince Edward Island. Newfoundland and Labrador, which is not part of the Maritimes, is also part of Atlantic Canada. The historical immigrants from Europe have shaped cultures and lexical catalogs across the regions of Atlantic Canada that reflect British, Scottish, Gaelic, and French customs. The vernacular variations of English spoken in the Atlantic region of Canada. Newfoundland and Labrador English (NLE) possesses unique vocabulary compared to standard Canadian English. The Dictionary of Newfoundland English covers the vocabulary common to Newfoundlanders, such as Newfoundland \"screech rum\", a Newfoundland-specific brand of rum; mummering, referring to a Christmas tradition; and gut-foundered, meaning starving or fastened. Nova Scotia also is home to its own vocabulary. The term \"Sobeys bag\", used to refer to a plastic grocery bag, originates from the Nova Scotian grocery store chain Sobeys. Similarly, Prince Edward Island has its own vocabulary and dictionary. For example, angishore refers to a fisherman who is too lazy to fish and likely is a lexical item originating from Irish Gaelic settlers in Newfoundland. Sarah Sawler, a writer from Halifax, highlights terms that are common to Maritimes, such as dooryard for front yard, owly for when someone is angry or irritable, and biff for throw.",
"title": "Vocabulary"
},
{
"paragraph_id": 64,
"text": "The term college, which refers to post-secondary education in general in the US, refers in Canada to either a post-secondary technical or vocational institution, or to one of the colleges that exist as federated schools within some Canadian universities. Most often, a college is a community college, not a university. It may also refer to a CEGEP in Quebec. In Canada, college student might denote someone obtaining a diploma in business management, an equivalent of this would be an associate degree in the United States. In contrast, university student is the term for someone earning a bachelor's degree, typically at a post-secondary university institution. Hence, the term going to college in Canada does not have the same meaning as going to university, unless the speaker or context clarifies the specific level of post-secondary education that is meant.",
"title": "Vocabulary"
},
{
"paragraph_id": 65,
"text": "Within the public school system the chief administrator of a school is generally \"the principal\", as in the United States, but the term is not used preceding their name, i.e., \"Principal Smith\". The assistant to the principal is not titled as \"assistant principal\", but rather as \"vice-principal\", although the former is not unknown. This usage is identical to that in Northern Ireland.",
"title": "Vocabulary"
},
{
"paragraph_id": 66,
"text": "Canadian universities publish calendars or schedules, not catalogs as in the US. Canadian students write or take exams (in the US, students generally \"take\" exams while teachers \"write\" them); they rarely sit them (standard British usage). Those who supervise students during an exam are sometimes called invigilators as in Britain, or sometimes proctors as in the US; usage may depend on the region or even the individual institution.",
"title": "Vocabulary"
},
{
"paragraph_id": 67,
"text": "Successive years of school are usually referred to as grade one, grade two, and so on. In Quebec, Francophone speakers will often say primary one, primary two as a direct translation from the French, and so on; while Anglophones will say grade one, grade two. These terms are comparable with the American first grade, second grade (which is used in Canada, yet is rare), English/Welsh Year 1, Year 2, Scottish/Northern Irish Primary 1, Primary 2 or P1, P2, and Southern Irish First Class, Second Class and so on. The year of school before grade 1 is usually called \"Kindergarten\", with the exception of Nova Scotia, where it is called \"grade primary\". In addition, children younger than the public school start age may attend 'pre-primary', although this is a newer addition to the Nova Scotian public-school system, and is not used frequently elsewhere.",
"title": "Vocabulary"
},
{
"paragraph_id": 68,
"text": "In parts of the US, the four years of high school are termed the freshman, sophomore, junior, and senior years (terms also used for college years); in Canada, the specific levels are used instead, such as \"grade nine\" in lieu of freshman. As for higher education, only the term freshman (often reduced to frosh) has some currency in Canada. Moreover, some Canadian public-school systems have adolescents start high-school in 'Grade 10' or, the sophomore year, although, this can depend on the province and even vary within a school-district. The American usages \"sophomore\", \"junior\" and \"senior\" are not used in Canadian university terminology, or in speech. The specific high-school grades and university years are therefore stated and individualized; for example, 'Sarah is starting Grade 10 this year', which Americans would state as 'Sarah is going to be a sophomore this year'. Similarly in the post-secondary education context, 'Francois is in second year of university' rather than the Americanism 'Francois is a sophomore in university'.",
"title": "Vocabulary"
},
{
"paragraph_id": 69,
"text": "Canadian students use the term marks (more common in England) or grades (more common in the US) to refer to their results. Usage is mixed, although marks more commonly refer to a single score whereas grades often refers to the cumulative score in that class.",
"title": "Vocabulary"
},
{
"paragraph_id": 70,
"text": "Unlike in the United States, use of metric units within a majority of industries is standard in Canada, as a result of the partial national adoption of the metric system during the mid-to-late 1970s that was eventually stalled; this has spawned some colloquial usages such as klick for kilometre.",
"title": "Vocabulary"
},
{
"paragraph_id": 71,
"text": "Nonetheless, US units are still used in many situations. Imperial volumes are also used, albeit rarely—although many Canadians and Americans mistakenly conflate the measurement systems despite their slight differences from each other (e.g. US and metric cups are 237ml and 250ml, respectively).",
"title": "Vocabulary"
},
{
"paragraph_id": 72,
"text": "For example, most English Canadians state their weight and height in pounds and feet/inches, respectively. This is also the case for many Quebec Francophones. Distances while playing golf are always marked and discussed in yards, though official scorecards may also show metres. Temperatures for cooking or pools are often given in Fahrenheit, while the weather is given in Celsius. Directions in the Prairie provinces are sometimes given using miles, because the country roads generally follow the mile-based grid of the Dominion Land Survey. Motor vehicle speed limits are measured in kilometres per hour.",
"title": "Vocabulary"
},
{
"paragraph_id": 73,
"text": "Canadians measure property, both residential and commercial, floor areas are in square feet or square metres, property is in square feet, square metres, acres or hectares. Fuel efficiency is more often discussed in the metric L/100 km than miles per US gallon. The Letter paper size of 8.5 inches × 11 inches is used instead of the international and metric equivalent A4 size of 210 mm × 297 mm. Beer cans are 355 mL (12 US oz), while beer bottles are typically 341 mL (12 Imperial oz), and draft beer is sold in various units; US or Imperial oz, US or Imperial pint, or occasionally mL.",
"title": "Vocabulary"
},
{
"paragraph_id": 74,
"text": "Building materials are used in soft conversions of imperial sizes, but often purchased in relation to the imperial sizes. For example, 8-inch concrete masonry units can be referred to as an 8-inch CMU or 190 CMU. The actual material used in the US and Canada is the same.",
"title": "Vocabulary"
},
{
"paragraph_id": 75,
"text": "Expressway may also refer to a limited-access road that has control of access but has at-grade junctions, railway crossings (for example, the Harbour Expressway in Thunder Bay.) Sometimes the term Parkway is also used (for example, the Hanlon Parkway in Guelph). In Saskatchewan, the term 'grid road' is used to refer to minor highways or rural roads, usually gravel, referring to the 'grid' upon which they were originally designed. In Quebec, freeways and expressways are called autoroutes.",
"title": "Vocabulary"
},
{
"paragraph_id": 76,
"text": "In Alberta, the generic Trail is often used to describe a freeway, expressway or major urban street (for example, Deerfoot Trail, Macleod Trail or Crowchild Trail in Calgary, Yellowhead Trail, Victoria Trail or Mark Messier/St.Albert Trail in Edmonton). The British term motorway is not used. The American terms turnpike and tollway for a toll road are not common. The term throughway or thruway was used for first tolled limited-access highways (for example, the Deas Island Throughway, now Highway 99, from Vancouver, BC, to Blaine, Washington, USA or the Saint John Throughway (Highway 1) in Saint John, NB), but this term is not common anymore. In everyday speech, when a particular roadway is not being specified, the term highway is generally or exclusively used.",
"title": "Vocabulary"
},
{
"paragraph_id": 77,
"text": "Lawyers in all parts of Canada, except Quebec, which has its own civil law system, are called \"barristers and solicitors\" because any lawyer licensed in any of the common law provinces and territories must pass bar exams for, and is permitted to engage in, both types of legal practice in contrast to other common-law jurisdictions such as England, Wales and Ireland where the two are traditionally separated (i.e., Canada has a fused legal profession). The words lawyer and counsel (not counsellor) predominate in everyday contexts; the word attorney refers to any personal representative. Canadian lawyers generally do not refer to themselves as \"attorneys\", a term that is common in the United States.",
"title": "Vocabulary"
},
{
"paragraph_id": 78,
"text": "The equivalent of an American district attorney, meaning the barrister representing the state in criminal proceedings, is called a crown attorney (in Ontario), crown counsel (in British Columbia), crown prosecutor or the crown, on account of Canada's status as a constitutional monarchy in which the Crown is the locus of state power.",
"title": "Vocabulary"
},
{
"paragraph_id": 79,
"text": "The words advocate and notary – two distinct professions in Quebec civil law – are used to refer to that province's approximate equivalents of barrister and solicitor, respectively. It is not uncommon for English-speaking advocates in Quebec to refer to themselves in English as \"barrister(s) and solicitor(s)\", as most advocates chiefly perform what would traditionally be known as \"solicitor's work\", while only a minority of advocates actually appear in court. In Canada's common law provinces and territories, the word notary means strictly a notary public.",
"title": "Vocabulary"
},
{
"paragraph_id": 80,
"text": "Within the Canadian legal community itself, the word solicitor is often used to refer to any Canadian lawyer in general (much like the way the word attorney is used in the United States to refer to any American lawyer in general). Despite the conceptual distinction between barrister and solicitor, Canadian court documents would contain a phrase such as \"John Smith, solicitor for the Plaintiff\" even though \"John Smith\" may well himself be the barrister who argues the case in court. In a letter introducing him/herself to an opposing lawyer, a Canadian lawyer normally writes something like \"I am the solicitor\" for Mr. Tom Jones.\"",
"title": "Vocabulary"
},
{
"paragraph_id": 81,
"text": "The word litigator is also used by lawyers to refer to a fellow lawyer who specializes in lawsuits even though the more traditional word barrister is still employed to denote the same specialization.",
"title": "Vocabulary"
},
{
"paragraph_id": 82,
"text": "Judges of Canada's superior courts, which exist at the provincial and territorial levels, are traditionally addressed as \"My Lord\" or \"My Lady\". This varies by jurisdiction, and some superior court judges prefer the titles \"Mister Justice\" or \"Madam Justice\" to \"Lordship\".",
"title": "Vocabulary"
},
{
"paragraph_id": 83,
"text": "Masters are addressed as \"Mr. Master\" or simply \"Sir.\" In British Columbia, masters are addressed as \"Your Honour.\"",
"title": "Vocabulary"
},
{
"paragraph_id": 84,
"text": "Judges of provincial or inferior courts are traditionally referred to in person as \"Your Honour\". Judges of the Supreme Court of Canada and of the federal-level courts prefer the use of \"Mister/Madam (Chief) Justice\". Justices of The Peace are addressed as \"Your Worship\". \"Your Honour\" is also the correct form of address for a Lieutenant Governor.",
"title": "Vocabulary"
},
{
"paragraph_id": 85,
"text": "A serious crime is called an indictable offence, while a less-serious crime is called a summary conviction offence. The older words felony and misdemeanour, which are still used in the United States, are not used in Canada's current Criminal Code (R.S.C. 1985, c. C-46) or by today's Canadian legal system. As noted throughout the Criminal Code, a person accused of a crime is called the accused and not the defendant, a term used instead in civil lawsuits.",
"title": "Vocabulary"
},
{
"paragraph_id": 86,
"text": "In Canada, visible minority refers to a non-aboriginal person or group visibly not one of the majority race in a given population. The term comes from the Canadian Employment Equity Act, which defines such people as \"persons, other than Aboriginal people, who are non-Caucasian in race or non-white in colour.\" The term is used as a demographic category by Statistics Canada. The qualifier \"visible\" is used to distinguish such minorities from the \"invisible\" minorities determined by language (English vs. French) and certain distinctions in religion (Catholics vs. Protestants).",
"title": "Vocabulary"
},
{
"paragraph_id": 87,
"text": "A county in British Columbia means only a regional jurisdiction of the courts and justice system and is not otherwise connected to governance as with counties in other provinces and in the United States. The rough equivalent to \"county\" as used elsewhere is a \"Regional District\".",
"title": "Vocabulary"
},
{
"paragraph_id": 88,
"text": "Distinctive Canadianisms are:",
"title": "Vocabulary"
},
{
"paragraph_id": 89,
"text": "Terms common in Canada, Britain and Ireland but less frequent or nonexistent in the United States are:",
"title": "Vocabulary"
},
{
"paragraph_id": 90,
"text": "The following are more or less distinctively Canadian:",
"title": "Vocabulary"
},
{
"paragraph_id": 91,
"text": "The following are common in Canada, but not in the United States or the United Kingdom.",
"title": "Vocabulary"
},
{
"paragraph_id": 92,
"text": "One of the most distinctive Canadian phrases is the spoken interrogation or tag eh. The only usage of eh exclusive to Canada, according to the Canadian Oxford Dictionary, is for \"ascertaining the comprehension, continued interest, agreement, etc., of the person or persons addressed\" as in, \"It's four kilometres away, eh, so I have to go by bike.\" In that case, eh? is used to confirm the attention of the listener and to invite a supportive noise such as mm or oh or okay. This usage is also common in Queensland, Australia and New Zealand. Other uses of eh – for instance, in place of huh? or what? meaning \"please repeat or say again\" – are also found in parts of the British Isles and Australia. It is common in Northern/Central Ontario, the Maritimes and the Prairie provinces. The word eh is used quite frequently in the North Central dialect, so a Canadian accent is often perceived in people from North Dakota, Michigan, Minnesota, and Wisconsin.",
"title": "Vocabulary"
},
{
"paragraph_id": 93,
"text": "A rubber in the US and Canada is slang for a condom. In Canada, it sometimes means an eraser (as in the United Kingdom and Ireland).",
"title": "Vocabulary"
},
{
"paragraph_id": 94,
"text": "The word bum can refer either to the buttocks (as in Britain), or to a homeless person (as in the US). The \"buttocks\" sense does not have the indecent character it retains in British use, as it and \"butt\" are commonly used as a polite or childish euphemism for ruder words such as arse (commonly used in Atlantic Canada and among older people in Ontario and to the west) or ass, or mitiss (used in the Prairie Provinces, especially in northern and central Saskatchewan; probably originally a Cree loanword). Older Canadians may see \"bum\" as more polite than \"butt\", which before the 1980s was often considered rude.",
"title": "Vocabulary"
},
{
"paragraph_id": 95,
"text": "Similarly the word pissed can refer either to being drunk (as in Britain), or being angry (as in the US), though anger is more often said as pissed off, while piss drunk or pissed up is said to describe inebriation (though piss drunk is sometimes also used in the US, especially in the northern states).",
"title": "Vocabulary"
},
{
"paragraph_id": 96,
"text": "The term Canuck simply means Canadian in its demonymic form, and, as a term used even by Canadians themselves, it is not considered derogatory. (In the 19th century and early 20th century it tended to refer to French-Canadians.) The only Canadian-built version of the popular World War I-era American Curtiss JN-4 Jenny training biplane aircraft, the JN-4C, 1,260 of which were built, got the \"Canuck\" nickname; so did another aircraft, the Fleet Model 80, built from the mid-1940s until the late 1950s. The nickname Janey Canuck was used by Anglophone women's rights writer Emily Murphy in the 1920s and the Johnny Canuck comic book character of the 1940s. Throughout the 1970s, Canada's winning World Cup men's downhill ski team was called the \"Crazy Canucks\" for their fearlessness on the slopes. It is also the name of the Vancouver Canucks, the National Hockey League team of Vancouver, British Columbia.",
"title": "Vocabulary"
},
{
"paragraph_id": 97,
"text": "The term hoser, popularized by Bob & Doug McKenzie, typically refers to an uncouth, beer-swilling male and is a euphemism for \"loser\" coming from the earlier days of hockey played on an outdoor rink and the losing team would have to hose down the ice after the game so it froze smooth. Bob & Doug also popularized the use of Beauty, eh, another western slang term which may be used to describe something as being of interest or note or deserving approval.",
"title": "Vocabulary"
},
{
"paragraph_id": 98,
"text": "A Newf or Newfie is someone from Newfoundland and Labrador; sometimes considered derogatory. In Newfoundland, the term Mainlander refers to any Canadian (sometimes American, occasionally Labradorian) not from the island of Newfoundland. Mainlander is also occasionally used derogatorily.",
"title": "Vocabulary"
},
{
"paragraph_id": 99,
"text": "In the Maritimes, a Caper or \"Cape Bretoner\" is someone from Cape Breton Island, a Bluenoser is someone with a thick, usually southern Nova Scotia accent or as a general term for a Nova Scotian (including Cape Bretoners), while an Islander is someone from Prince Edward Island (the same term is used in British Columbia for people from Vancouver Island, or the numerous islands along it). A Haligonian refers to someone from the city of Halifax.",
"title": "Vocabulary"
},
{
"paragraph_id": 100,
"text": "Cape Bretoners and Newfies (from Newfoundland and Labrador) often have similar slang. \"Barmp\" is often used as the sound a car horn makes, example: \"He cut me off so I barmped the horn at him\". When saying \"B'y\", while sounds like the traditional farewell, it is a syncopated shortening of the word \"boy\", referring to a person, example: \"How's it goin, b'y?\". Another slang that is commonly used is \"doohickey\" which means an object, example: \"Pass me that doohickey over there\". When an individual uses the word \"biffed\", they mean that they threw something. Example: \"I got frustrated so I biffed it across the room\".",
"title": "Vocabulary"
},
{
"paragraph_id": 101,
"text": "In language studies, there are three basic types of data collection: introspection, elicitation, and observation. Introspection relies on the idea that native speakers are the best judges of sentence structure and can provide valuable data, but it can be limiting because it only requires one native speaker. Elicitation requires more effort, but is a widespread technique used to gather linguistic structures by asking informants how they say certain things in their language. Observation is considered the \"gold standard\" by many linguists because it involves collecting utterances after the fact and systematically analyzing them. This can be done through corpora, which are collections of spoken or written text, but most corpus material today consists of written texts since they are more easily accessible. Variationist sociolinguistics aim to elicit data that is as natural and informal as possible, using techniques such as sociolinguistic interviews to gather different speech styles.",
"title": "Vocabulary"
},
{
"paragraph_id": 102,
"text": "The use of written questionnaires (WQs) in dialectology were once popular for surveying language use, but fell out of favor before being re-examined in recent years. While they were once considered less effective than other survey methods, scholars have started to recognize their potential in social dialectology and variation studies. In the early 1950s, McDavid noted the value of using a lexical WQ for the Linguistic Atlas of Scotland, but later, Chambers and Trudgill stated that WQs were no longer the primary method of data-gathering. However, within the past 15 years, WQs have experienced renewed interest in social dialectology and variation studies. WQs can provide linguistic information about behavior and can be used for self-reporting or community reporting.",
"title": "Vocabulary"
},
{
"paragraph_id": 103,
"text": "Scholars have used five types of questionnaires in sociolinguistics. Dollinger suggests a three-tiered WQ question typology. The first tier covers questions about regional language variation and social language variation. The second tier covers language perception and attitudes, while the third tier deals with acceptability judgments of grammaticality. The questions can be classified by subject area, type of reporting, and the type of information sought. This classification can help scholars better utilize WQs and understand their potential.",
"title": "Vocabulary"
},
{
"paragraph_id": 104,
"text": "Written surveys are commonly used in dialectology as regional differences are less socially sensitive. However, they can still be used in sociolinguistics if handled properly. A survey's advantage is its quantitative approach since it is capable of collecting large amounts of data within a relatively short time. This would allow researchers to have a more robust statistical analysis and reliable or accurate conclusions about regional or social patterns. Despite its advantages, there are still disadvantages using surveys for a research study particularly in capturing natural speech patterns due to the observer's paradox. Through its unique format, surveys containing direct questions about language may not provide sufficient enough information on how often or in what social or linguistic contexts people use distinct language features. Therefore, by relying on systematic observations, local participants may adhere to perceived norms or expectations. While written surveys can provide valuable information about sociolinguistic variables in Canadian English, data gathered from surveys or questionnaires should not be perceived as equivalent to data gathered from the usage of actual speech. William Labov, a linguist, suggests that in order to solve this problem is to change the style of approach of surveys. Therefore, he suggests that researchers design sociolinguistic interviews that manipulate attention to speech. By comparing the speech among research participants when they are being directly questioned about language with their speech when talking about their personal experience, Labov could observe how the usage of language within different contexts or environments. This newly suggested approach allowed Labov to capture the \"vernacular\" which is the casual style of speech that people use within a day-to-day basis when they are not being observed.",
"title": "Vocabulary"
},
{
"paragraph_id": 105,
"text": "Canadian English dialectology examines Canadian English through the use of written surveys due to the vastness of the country and the difficulties of conducting face-to-face interviews on a nationwide level. The historical overview of written surveys in Canadian-English dialectology includes Avis's study of speech differences among the Ontario-United States borders through the use of questionnaires. Another example is the Survey of Canadian English directed by Scargill. A more recent example would be Nylvek's survey of Saskatchewan English and Chambers' trans-Canada dialect questionnaires.",
"title": "Vocabulary"
},
{
"paragraph_id": 106,
"text": "An attitude study in the late 1970s revealed a positive attitude toward Canadian linguistic features. Features include front vowel merger before/r/, low-back vowel merger, Canadian Raising, and Canadian lexical items. Still, the sample group in British Columbia showed a preference for UK and US English.",
"title": "Attitudes"
},
{
"paragraph_id": 107,
"text": "This attitude sees a change years later. A survey about attitudes towards CE was conducted with a diverse sample group in Vancouver, BC, in 2009. Among 429 Vancouverites, 81.1% believe there is a Canadian way of speaking English, 72.9% can tell CanE speakers from American English speakers, 69.1% consider CanE a part of their Canadian identity, and 74.1% think CanE should be taught in schools. Due to the unavailability of free and easy-to-access CanE dictionaries, many Canadian opt for other non-Canadian English dictionaries today. Historically, American, British, and Irish texts are used in Canadian schools for the most part; even though Canadian reference work was written and became available in the 1960s, they were never preferred as teaching material.",
"title": "Attitudes"
},
{
"paragraph_id": 108,
"text": "A preference change can be seen at the end of higher education in Canada. At the University of Toronto's Graduate English department, \"Canadian English\" and a \"consistent spelling\" are officially \"the standard for all Ph.D. dissertations,\" with the Canadian Oxford English Dictionary as the official guideline. However, there is no mention of which grammar guide was to be followed because there was never a solid standard developed for spelling and grammar.",
"title": "Attitudes"
},
{
"paragraph_id": 109,
"text": "In 2011, just under 21.5 million Canadians, representing 65% of the population, spoke English most of the time at home, while 58% declared it their mother language. English is the major language everywhere in Canada except Quebec, and most Canadians (85%) can speak English. While English is not the preferred language in Quebec, 36.1% of the Québécois can speak English. Nationally, Francophones are five times more likely to speak English than Anglophones are to speak French – 44% and 9% respectively. Only 3.2% of Canada's English-speaking population resides in Quebec—mostly in Montreal.",
"title": "Attitudes"
},
{
"paragraph_id": 110,
"text": "A study conducted in 2002 inquired Canadians from Ontario and Alberta about the \"pleasantness\" and \"correctness\" of different varieties of Canadian English based on province. Albertans and Ontarians all seem to rate their English and BC English in the top three. However, both hold a low opinion of Quebec English. Unlike the assumption that Toronto or Ontario English would be the most prestigious considering these regions are the most economically robust, BC had the best public opinion regarding pleasantness and correctness among the participants.",
"title": "Attitudes"
},
{
"paragraph_id": 111,
"text": "Jaan Lilles argues in an essay for English Today that there is no variety of \"Canadian English\". According to Lilles, a former M.A. student, Canadian English is simply not a \"useful fiction\". He goes on to argue that too often supposedly unique features of Canadian speakers, such as certain lexical terms such as muskeg are artificially exaggerated to distinguish Canadian speech primarily from that found in the United States. Lilles was heavily critiqued in the next issue of English Today by lexicographer Fraser Sutherland and others. According to Stefan Dollinger, Lilles' paper \"is not a paper based on any data or other new information but more of a pamphlet – so much so that it should not have been published without a public critique\". He continues: \"The paper is insightful for different reasons: it is a powerful testimony of personal anecdote and opinion [...]. As an opinion piece, it offers a good debating case.\" As a linguistic account, however, it \"essentializes a prior state, before Canada was an independent political entity\".",
"title": "Attitudes"
},
{
"paragraph_id": 112,
"text": "Dollinger, Stefan (2015). The Written Questionnaire in Social Dialectology: History, Theory, Practice. Archived 18 May 2016 at the Wayback Machine Amsterdam/Philadelphia: Benjamins. The book's examples are exclusive taken from Canadian English and represent one of the more extensive collections of variables for Canadian English.",
"title": "Further reading"
},
{
"paragraph_id": 113,
"text": "The dictionary definition of Canadian English at Wiktionary",
"title": "External links"
}
] | Canadian English encompasses the varieties of English used in Canada, while Standard Canadian English is the Canadian standard variety of English. According to the 2016 census, English was the first language of 19.4 million Canadians or 58.1% of the total population; the remainder spoke French (20.8%) or other languages (21.1%). In Quebec, 7.5% of the population are anglophone, as most of Quebec's residents are native speakers of Quebec French. Phonologically, Standard Canadian and General American English may be grouped together as North American English, emphasizing the two varieties' identical phonemic inventories, whose realizations, however, differ. While Canadian English tends to be closer to American English in most regards, it does possess elements from British English and some uniquely Canadian characteristics. The precise influence of American English, British English and other sources on Canadian English varieties has been the ongoing focus of systematic studies since the 1950s. Canadians and Americans themselves often have trouble differentiating their own two accents, particularly when someone speaks with an urban Standard Canadian English accent because it sounds similar to Western American English. There is also evidence that Standard Canadian English and Western American English have been undergoing a similar vowel shift since the 1980s. Canadian English varies little from Central Canada to British Columbia. But, some noticeably different accents can be found in the Atlantic provinces, most especially in Newfoundland with Newfoundland English. Accent differences can sometimes be heard between those who live in urban centres versus those living in rural settings. In the early 20th century, western Canada was largely populated by farmers from Central and Eastern Europe who were not anglophones. At the time, most anglophones there were re-settlers from Ontario or Quebec who had British, Irish and/or Loyalist ancestry. Throughout the 20th century, the prairies underwent anglicization and linguistic homogenization through education and exposure to Canadian and American media. | 2001-11-03T21:00:54Z | 2023-12-31T18:53:53Z | [
"Template:Not a typo",
"Template:Cite web",
"Template:Further",
"Template:'s",
"Template:Citation needed",
"Template:IPA",
"Template:IPAc-en",
"Template:Respell",
"Template:Lang",
"Template:Cite thesis",
"Template:Infobox language",
"Template:Wiktionary-inline",
"Template:Use Canadian English",
"Template:Main",
"Template:Sic",
"Template:Redirect",
"Template:English language",
"Template:Page needed",
"Template:Cite journal",
"Template:Short description",
"Template:IPAblink",
"Template:Clarify",
"Template:Cite news",
"Template:Refbegin",
"Template:Authority control",
"Template:Anchor",
"Template:Reflist",
"Template:Cite book",
"Template:Cite conference",
"Template:Citation",
"Template:Navboxes",
"Template:Clarification needed",
"Template:Harvcoltxt",
"Template:See also",
"Template:Refn",
"Template:Webarchive",
"Template:Crossreference",
"Template:Sfn",
"Template:Convert",
"Template:Portal",
"Template:ISBN",
"Template:Refend",
"Template:Use dmy dates"
] | https://en.wikipedia.org/wiki/Canadian_English |
6,343 | Czech language | Czech (/tʃɛk/; čeština [ˈtʃɛʃcɪna]), historically also known as Bohemian (/boʊˈhiːmiən, bə-/; Latin: lingua Bohemica), is a West Slavic language of the Czech–Slovak group, written in Latin script. Spoken by over 10 million people, it serves as the official language of the Czech Republic. Czech is closely related to Slovak, to the point of high mutual intelligibility, as well as to Polish to a lesser degree. Czech is a fusional language with a rich system of morphology and relatively flexible word order. Its vocabulary has been extensively influenced by Latin and German.
The Czech–Slovak group developed within West Slavic in the high medieval period, and the standardization of Czech and Slovak within the Czech–Slovak dialect continuum emerged in the early modern period. In the later 18th to mid-19th century, the modern written standard became codified in the context of the Czech National Revival. The main non-standard variety, known as Common Czech, is based on the vernacular of Prague, but is now spoken as an interdialect throughout most of the Czech Republic. The Moravian dialects spoken in the eastern part of the country are also classified as Czech, although some of their eastern variants are closer to Slovak.
Czech has a moderately-sized phoneme inventory, comprising ten monophthongs, three diphthongs and 25 consonants (divided into "hard", "neutral" and "soft" categories). Words may contain complicated consonant clusters or lack vowels altogether. Czech has a raised alveolar trill, which is known to occur as a phoneme in only a few other languages, represented by the grapheme ř.
Czech is a member of the West Slavic sub-branch of the Slavic branch of the Indo-European language family. This branch includes Polish, Kashubian, Upper and Lower Sorbian and Slovak. Slovak is the most closely related language to Czech, followed by Polish and Silesian.
The West Slavic languages are spoken in Central Europe. Czech is distinguished from other West Slavic languages by a more-restricted distinction between "hard" and "soft" consonants (see Phonology below).
The term "Old Czech" is applied to the period predating the 16th century, with the earliest records of the high medieval period also classified as "early Old Czech", but the term "Medieval Czech" is also used. The function of the written language was initially performed by Old Slavonic written in Glagolitic, later by Latin written in Latin script.
Around the 7th century, the Slavic expansion reached Central Europe, settling on the eastern fringes of the Frankish Empire. The West Slavic polity of Great Moravia formed by the 9th century. The Christianization of Bohemia took place during the 9th and 10th centuries. The diversification of the Czech-Slovak group within West Slavic began around that time, marked among other things by its use of the voiced velar fricative consonant (/ɣ/) and consistent stress on the first syllable.
The Bohemian (Czech) language is first recorded in writing in glosses and short notes during the 12th to 13th centuries. Literary works written in Czech appear in the late 13th and early 14th century and administrative documents first appear towards the late 14th century. The first complete Bible translation, the Leskovec-Dresden Bible, also dates to this period. Old Czech texts, including poetry and cookbooks, were also produced outside universities.
Literary activity becomes widespread in the early 15th century in the context of the Bohemian Reformation. Jan Hus contributed significantly to the standardization of Czech orthography, advocated for widespread literacy among Czech commoners (particularly in religion) and made early efforts to model written Czech after the spoken language.
There was no standardization distinguishing between Czech and Slovak prior to the 15th century. In the 16th century, the division between Czech and Slovak becomes apparent, marking the confessional division between Lutheran Protestants in Slovakia using Czech orthography and Catholics, especially Slovak Jesuits, beginning to use a separate Slovak orthography based on Western Slovak dialects.
The publication of the Kralice Bible between 1579 and 1593 (the first complete Czech translation of the Bible from the original languages) became very important for standardization of the Czech language in the following centuries as it was used as a model for the standard language.
In 1615, the Bohemian diet tried to declare Czech to be the only official language of the kingdom. After the Bohemian Revolt (of predominantly Protestant aristocracy) which was defeated by the Habsburgs in 1620, the Protestant intellectuals had to leave the country. This emigration together with other consequences of the Thirty Years' War had a negative impact on the further use of the Czech language. In 1627, Czech and German became official languages of the Kingdom of Bohemia and in the 18th century German became dominant in Bohemia and Moravia, especially among the upper classes.
The modern standard Czech language originates in standardization efforts of the 18th century. By then the language had developed a literary tradition, and since then it has changed little; journals from that period have no substantial differences from modern standard Czech, and contemporary Czechs can understand them with little difficulty. Sometime before the 18th century, the Czech language abandoned a distinction between phonemic /l/ and /ʎ/ which survives in Slovak.
With the beginning of the national revival of the mid-18th century, Czech historians began to emphasize their people's accomplishments from the 15th through the 17th centuries, rebelling against the Counter-Reformation (the Habsburg re-catholization efforts which had denigrated Czech and other non-Latin languages). Czech philologists studied sixteenth-century texts, advocating the return of the language to high culture. This period is known as the Czech National Revival (or Renaissance).
During the national revival, in 1809 linguist and historian Josef Dobrovský released a German-language grammar of Old Czech entitled Ausführliches Lehrgebäude der böhmischen Sprache ('Comprehensive Doctrine of the Bohemian Language'). Dobrovský had intended his book to be descriptive, and did not think Czech had a realistic chance of returning as a major language. However, Josef Jungmann and other revivalists used Dobrovský's book to advocate for a Czech linguistic revival. Changes during this time included spelling reform (notably, í in place of the former j and j in place of g), the use of t (rather than ti) to end infinitive verbs and the non-capitalization of nouns (which had been a late borrowing from German). These changes differentiated Czech from Slovak. Modern scholars disagree about whether the conservative revivalists were motivated by nationalism or considered contemporary spoken Czech unsuitable for formal, widespread use.
Adherence to historical patterns was later relaxed and standard Czech adopted a number of features from Common Czech (a widespread, informally used interdialectal variety), such as leaving some proper nouns undeclined. This has resulted in a relatively high level of homogeneity among all varieties of the language.
Czech is spoken by about 10 million residents of the Czech Republic. A Eurobarometer survey conducted from January to March 2012 found that the first language of 98 percent of Czech citizens was Czech, the third-highest proportion of a population in the European Union (behind Greece and Hungary).
As the official language of the Czech Republic (a member of the European Union since 2004), Czech is one of the EU's official languages and the 2012 Eurobarometer survey found that Czech was the foreign language most often used in Slovakia. Economist Jonathan van Parys collected data on language knowledge in Europe for the 2012 European Day of Languages. The five countries with the greatest use of Czech were the Czech Republic (98.77 percent), Slovakia (24.86 percent), Portugal (1.93 percent), Poland (0.98 percent) and Germany (0.47 percent).
Czech speakers in Slovakia primarily live in cities. Since it is a recognized minority language in Slovakia, Slovak citizens who speak only Czech may communicate with the government in their language to the extent that Slovak speakers in the Czech Republic may do so.
Immigration of Czechs from Europe to the United States occurred primarily from 1848 to 1914. Czech is a Less Commonly Taught Language in U.S. schools, and is taught at Czech heritage centers. Large communities of Czech Americans live in the states of Texas, Nebraska and Wisconsin. In the 2000 United States Census, Czech was reported as the commonest language spoken at home (besides English) in Valley, Butler and Saunders Counties, Nebraska and Republic County, Kansas. With the exception of Spanish (the non-English language most commonly spoken at home nationwide), Czech was the most common home language in more than a dozen additional counties in Nebraska, Kansas, Texas, North Dakota and Minnesota. As of 2009, 70,500 Americans spoke Czech as their first language (49th place nationwide, after Turkish and before Swedish).
Standard Czech contains ten basic vowel phonemes, and three diphthongs. The vowels are /a/, /ɛ/, /ɪ/, /o/, and /u/, and their long counterparts /aː/, /ɛː/, /iː/, /oː/ and /uː/. The diphthongs are /ou̯/, /au̯/ and /ɛu̯/; the last two are found only in loanwords such as auto "car" and euro "euro".
In Czech orthography, the vowels are spelled as follows:
The letter ⟨ě⟩ indicates that the previous consonant is palatalized (e.g. něco /ɲɛt͡so/). After a labial it represents /jɛ/ (e.g. běs /bjɛs/); but ⟨mě⟩ is pronounced /mɲɛ/, cf. měkký (/mɲɛkiː/).
The consonant phonemes of Czech and their equivalent letters in Czech orthography are as follows:
Czech consonants are categorized as "hard", "neutral", or "soft":
Hard consonants may not be followed by i or í in writing, or soft ones by y or ý (except in loanwords such as kilogram). Neutral consonants may take either character. Hard consonants are sometimes known as "strong", and soft ones as "weak". This distinction is also relevant to the declension patterns of nouns, which vary according to whether the final consonant of the noun stem is hard or soft.
Voiced consonants with unvoiced counterparts are unvoiced at the end of a word before a pause, and in consonant clusters voicing assimilation occurs, which matches voicing to the following consonant. The unvoiced counterpart of /ɦ/ is /x/.
The phoneme represented by the letter ř (capital Ř) is very rare among languages and often claimed to be unique to Czech, though it also occurs in some dialects of Kashubian, and formerly occurred in Polish. It represents the raised alveolar non-sonorant trill (IPA: [r̝]), a sound somewhere between Czech r and ž (example: "řeka" (river)), and is present in Dvořák. In unvoiced environments, /r̝/ is realized as its voiceless allophone [r̝̊], a sound somewhere between Czech r and š.
The consonants /r/, /l/, and /m/ can be syllabic, acting as syllable nuclei in place of a vowel. Strč prst skrz krk ("Stick [your] finger through [your] throat") is a well-known Czech tongue twister using syllabic consonants but no vowels.
Each word has primary stress on its first syllable, except for enclitics (minor, monosyllabic, unstressed syllables). In all words of more than two syllables, every odd-numbered syllable receives secondary stress. Stress is unrelated to vowel length; both long and short vowels can be stressed or unstressed. Vowels are never reduced in tone (e.g. to schwa sounds) when unstressed. When a noun is preceded by a monosyllabic preposition, the stress usually moves to the preposition, e.g. do Prahy "to Prague".
Czech grammar, like that of other Slavic languages, is fusional; its nouns, verbs, and adjectives are inflected by phonological processes to modify their meanings and grammatical functions, and the easily separable affixes characteristic of agglutinative languages are limited. Czech inflects for case, gender and number in nouns and tense, aspect, mood, person and subject number and gender in verbs.
Parts of speech include adjectives, adverbs, numbers, interrogative words, prepositions, conjunctions and interjections. Adverbs are primarily formed from adjectives by taking the final ý or í of the base form and replacing it with e, ě, y, or o. Negative statements are formed by adding the affix ne- to the main verb of a clause, with one exception: je (he, she or it is) becomes není.
Because Czech uses grammatical case to convey word function in a sentence (instead of relying on word order, as English does), its word order is flexible. As a pro-drop language, in Czech an intransitive sentence can consist of only a verb; information about its subject is encoded in the verb. Enclitics (primarily auxiliary verbs and pronouns) appear in the second syntactic slot of a sentence, after the first stressed unit. The first slot can contain a subject or object, a main form of a verb, an adverb, or a conjunction (except for the light conjunctions a, "and", i, "and even" or ale, "but").
Czech syntax has a subject–verb–object sentence structure. In practice, however, word order is flexible and used to distinguish topic and focus, with the topic or theme (known referents) preceding the focus or rheme (new information) in a sentence; Czech has therefore been described as a topic-prominent language. Although Czech has a periphrastic passive construction (like English), in colloquial style, word-order changes frequently replace the passive voice. For example, to change "Peter killed Paul" to "Paul was killed by Peter" the order of subject and object is inverted: Petr zabil Pavla ("Peter killed Paul") becomes "Paul, Peter killed" (Pavla zabil Petr). Pavla is in the accusative case, the grammatical object of the verb.
A word at the end of a clause is typically emphasized, unless an upward intonation indicates that the sentence is a question:
In parts of Bohemia (including Prague), questions such as Jí pes bagetu? without an interrogative word (such as co, "what" or kdo, "who") are intoned in a slow rise from low to high, quickly dropping to low on the last word or phrase.
In modern Czech syntax, adjectives precede nouns, with few exceptions. Relative clauses are introduced by relativizers such as the adjective který, analogous to the English relative pronouns "which", "that" and "who"/"whom". As with other adjectives, it agrees with its associated noun in gender, number and case. Relative clauses follow the noun they modify. The following is a glossed example:
Chc-i
want-1SG
navštív-it
visit-INF
universit-u,
university-SG.ACC,
na
on
kter-ou
which-SG.F.ACC
chod-í
attend-3SG
Jan.
John.SG.NOM
Chc-i navštív-it universit-u, na kter-ou chod-í Jan.
want-1SG visit-INF university-SG.ACC, on which-SG.F.ACC attend-3SG John.SG.NOM
I want to visit the university that John attends.
In Czech, nouns and adjectives are declined into one of seven grammatical cases which indicate their function in a sentence, two numbers (singular and plural) and three genders (masculine, feminine and neuter). The masculine gender is further divided into animate and inanimate classes.
A nominative–accusative language, Czech marks subject nouns of transitive and intransitive verbs in the nominative case, which is the form found in dictionaries, and direct objects of transitive verbs are declined in the accusative case. The vocative case is used to address people. The remaining cases (genitive, dative, locative and instrumental) indicate semantic relationships, such as noun adjuncts (genitive), indirect objects (dative), or agents in passive constructions (instrumental). Additionally prepositions and some verbs require their complements to be declined in a certain case. The locative case is only used after prepositions. An adjective's case agrees with that of the noun it modifies. When Czech children learn their language's declension patterns, the cases are referred to by number:
Some prepositions require the nouns they modify to take a particular case. The cases assigned by each preposition are based on the physical (or metaphorical) direction, or location, conveyed by it. For example, od (from, away from) and z (out of, off) assign the genitive case. Other prepositions take one of several cases, with their meaning dependent on the case; na means "onto" or "for" with the accusative case, but "on" with the locative.
This is a glossed example of a sentence using several cases:
Nes-l
carry-SG.M.PST
js-em
be-1.SG
krabic-i
box-SG.ACC
do
into
dom-u
house-SG.GEN
se
with
sv-ým
own-SG.INS
přítel-em.
friend-SG.INS
Nes-l js-em krabic-i do dom-u se sv-ým přítel-em.
carry-SG.M.PST be-1.SG box-SG.ACC into house-SG.GEN with own-SG.INS friend-SG.INS
I carried the box into the house with my friend.
Czech distinguishes three genders—masculine, feminine, and neuter—and the masculine gender is subdivided into animate and inanimate. With few exceptions, feminine nouns in the nominative case end in -a, -e, or a consonant; neuter nouns in -o, -e, or -í, and masculine nouns in a consonant. Adjectives, participles, most pronouns, and the numbers "one" and "two" are marked for gender and agree with the gender of the noun they modify or refer to. Past tense verbs are also marked for gender, agreeing with the gender of the subject, e.g. dělal (he did, or made); dělala (she did, or made) and dělalo (it did, or made). Gender also plays a semantic role; most nouns that describe people and animals, including personal names, have separate masculine and feminine forms which are normally formed by adding a suffix to the stem, for example Čech (Czech man) has the feminine form Češka (Czech woman).
Nouns of different genders follow different declension patterns. Examples of declension patterns for noun phrases of various genders follow:
Nouns are also inflected for number, distinguishing between singular and plural. Typical of a Slavic language, Czech cardinal numbers one through four allow the nouns and adjectives they modify to take any case, but numbers over five require subject and direct object noun phrases to be declined in the genitive plural instead of the nominative or accusative, and when used as subjects these phrases take singular verbs. For example:
Numbers decline for case, and the numbers one and two are also inflected for gender. Numbers one through five are shown below as examples. The number one has declension patterns identical to those of the demonstrative pronoun ten.
Although Czech's grammatical numbers are singular and plural, several residuals of dual forms remain, such as the words dva ("two") and oba ("both"), which decline the same way. Some nouns for paired body parts use a historical dual form to express plural in some cases: ruka (hand)—ruce (nominative); noha (leg)—nohama (instrumental), nohou (genitive/locative); oko (eye)—oči, and ucho (ear)—uši. While two of these nouns are neuter in their singular forms, all plural forms are considered feminine; their gender is relevant to their associated adjectives and verbs. These forms are plural semantically, used for any non-singular count, as in mezi čtyřma očima (face to face, lit. among four eyes). The plural number paradigms of these nouns are a mixture of historical dual and plural forms. For example, nohy (legs; nominative/accusative) is a standard plural form of this type of noun.
Czech verbs agree with their subjects in person (first, second or third), number (singular or plural), and in constructions involving participles, which includes the past tense, also in gender. They are conjugated for tense (past, present or future) and mood (indicative, imperative or conditional). For example, the conjugated verb mluvíme (we speak) is in the present tense and first-person plural; it is distinguished from other conjugations of the infinitive mluvit by its ending, -íme. The infinitive form of Czech verbs ends in -t (archaically, -ti or -ci). It is the form found in dictionaries and the form that follows auxiliary verbs (for example, můžu tě slyšet—"I can hear you").
Typical of Slavic languages, Czech marks its verbs for one of two grammatical aspects: perfective and imperfective. Most verbs are part of inflected aspect pairs—for example, koupit (perfective) and kupovat (imperfective). Although the verbs' meaning is similar, in perfective verbs the action is completed and in imperfective verbs it is ongoing or repeated. This is distinct from past and present tense. Any verb of either aspect can be conjugated into either the past or present tense, but the future tense is only used with imperfective verbs. Aspect describes the state of the action at the time specified by the tense.
The verbs of most aspect pairs differ in one of two ways: by prefix or by suffix. In prefix pairs, the perfective verb has an added prefix—for example, the imperfective psát (to write, to be writing) compared with the perfective napsat (to write down). The most common prefixes are na-, o-, po-, s-, u-, vy-, z- and za-. In suffix pairs, a different infinitive ending is added to the perfective stem; for example, the perfective verbs koupit (to buy) and prodat (to sell) have the imperfective forms kupovat and prodávat. Imperfective verbs may undergo further morphology to make other imperfective verbs (iterative and frequentative forms), denoting repeated or regular action. The verb jít (to go) has the iterative form chodit (to go regularly) and the frequentative form chodívat (to go occasionally; to tend to go).
Many verbs have only one aspect, and verbs describing continual states of being—být (to be), chtít (to want), moct (to be able to), ležet (to lie down, to be lying down)—have no perfective form. Conversely, verbs describing immediate states of change—for example, otěhotnět (to become pregnant) and nadchnout se (to become enthusiastic)—have no imperfective aspect.
The present tense in Czech is formed by adding an ending that agrees with the person and number of the subject at the end of the verb stem. As Czech is a null-subject language, the subject pronoun can be omitted unless it is needed for clarity. The past tense is formed using a participle which ends in -l and a further ending which agrees with the gender and number of the subject. For the first and second persons, the auxiliary verb být conjugated in the present tense is added.
In some contexts, the present tense of perfective verbs (which differs from the English present perfect) implies future action; in others, it connotes habitual action. The perfective present is used to refer to completion of actions in the future and is distinguished from the imperfective future tense, which refers to actions that will be ongoing in the future. The future tense is regularly formed using the future conjugation of být (as shown in the table on the left) and the infinitive of an imperfective verb, for example, budu jíst—"I will eat" or "I will be eating". Where budu has a noun or adjective complement it means "I will be", for example, budu šťastný (I will be happy). Some verbs of movement form their future tense by adding the prefix po- to the present tense forms instead, e.g. jedu ("I go") > pojedu ("I will go").
Czech verbs have three grammatical moods: indicative, imperative and conditional. The imperative mood is formed by adding specific endings for each of three person–number categories: -Ø/-i/-ej for second-person singular, -te/-ete/-ejte for second-person plural and -me/-eme/-ejme for first-person plural. Imperatives are usually expressed using perfective verbs if positive and imperfective verbs if negative. The conditional mood is formed with a conditional auxiliary verb after the participle ending in -l which is used to form the past tense. This mood indicates hypothetical events and can also be used to express wishes.
Most Czech verbs fall into one of five classes, which determine their conjugation patterns. The future tense of být would be classified as a Class I verb because of its endings. Examples of the present tense of each class and some common irregular verbs follow in the tables below:
Czech has one of the most phonemic orthographies of all European languages. Its alphabet contains 42 graphemes, most of which correspond to individual phonemes, and only contains only one digraph: ch, which follows h in the alphabet. The characters q, w and x appear only in foreign words. The háček (ˇ) is used with certain letters to form new characters: š, ž, and č, as well as ň, ě, ř, ť, and ď (the latter five uncommon outside Czech). The last two letters are sometimes written with a comma above (ʼ, an abbreviated háček) because of their height. Czech orthography has influenced the orthographies of other Balto-Slavic languages and some of its characters have been adopted for transliteration of Cyrillic.
Czech orthography reflects vowel length; long vowels are indicated by an acute accent or, in the case of the character ů, a ring. Long u is usually written ú at the beginning of a word or morpheme (úroda, neúrodný) and ů elsewhere, except for loanwords (skútr) or onomatopoeia (bú). Long vowels and ě are not considered separate letters in the alphabetical order. The character ó exists only in loanwords and onomatopoeia.
Czech typographical features not associated with phonetics generally resemble those of most European languages that use the Latin script, including English. Proper nouns, honorifics, and the first letters of quotations are capitalized, and punctuation is typical of other Latin European languages. Ordinal numbers (1st) use a point, as in German (1.). The Czech language uses a decimal comma instead of a decimal point. When writing a long number, spaces between every three digits, including those in decimal places, may be used for better orientation in handwritten texts. The number 1,234,567.89101 may be written as 1234567,89101 or 1 234 567,891 01. In proper noun phrases (except personal and settlement names), only the first word and proper nouns inside such phrases are capitalized (Pražský hrad, Prague Castle).
The modern literary standard and prestige variety, known as "Standard Czech" (spisovná čeština) is based on the standardization during the Czech National Revival in the 1830s, significantly influenced by Josef Jungmann's Czech–German dictionary published during 1834–1839. Jungmann used vocabulary of the Bible of Kralice (1579–1613) period and of the language used by his contemporaries. He borrowed words not present in Czech from other Slavic languages or created neologisms. Standard Czech is the formal register of the language which is used in official documents, formal literature, newspaper articles, education and occasionally public speeches. It is codified by the Czech Language Institute, who publish occasional reforms to the codification. The most recent reform took place in 1993. The term hovorová čeština (lit. "Colloquial Czech") is sometimes used to refer to the spoken variety of standard Czech.
The most widely spoken vernacular form of the language is called "Common Czech" (obecná čeština), an interdialect influenced by spoken Standard Czech and the Central Bohemian dialects of the Prague region. Other Bohemian regional dialects have become marginalized, while Moravian dialects remain more widespread and diverse, with a political movement for Moravian linguistic revival active since the 1990s.
These varieties of the language (Standard Czech, spoken/colloquial Standard Czech, Common Czech, and regional dialects) form a stylistic continuum, in which contact between varieties of a similar prestige influences change within them.
The main Czech vernacular, spoken primarily in Bohemia including the capital Prague, is known as Common Czech (obecná čeština). This is an academic distinction; most Czechs are unaware of the term or associate it with deformed or "incorrect" Czech. Compared to Standard Czech, Common Czech is characterized by simpler inflection patterns and differences in sound distribution.
Common Czech is distinguished from spoken/colloquial Standard Czech (hovorová čeština), which is a stylistic variety within standard Czech. Tomasz Kamusella defines the spoken variety of Standard Czech as a compromise between Common Czech and the written standard, while Miroslav Komárek calls Common Czech an intersection of spoken Standard Czech and regional dialects.
Common Czech has become ubiquitous in most parts of the Czech Republic since the later 20th century. It is usually defined as an interdialect used in common speech in Bohemia and western parts of Moravia (by about two thirds of all inhabitants of the Czech Republic). Common Czech is not codified, but some of its elements have become adopted in the written standard. Since the second half of the 20th century, Common Czech elements have also been spreading to regions previously unaffected, as a consequence of media influence. Standard Czech is still the norm for politicians, businesspeople and other Czechs in formal situations, but Common Czech is gaining ground in journalism and the mass media. The colloquial form of Standard Czech finds limited use in daily communication due to the expansion of the Common Czech interdialect. It is sometimes defined as a theoretical construct rather than an actual tool of colloquial communication, since in casual contexts, the non-standard interdialect is preferred.
Common Czech phonology is based on that of the Central Bohemian dialect group, which has a slightly different set of vowel phonemes to Standard Czech. The phoneme /ɛː/ is peripheral and usually merges with /iː/, e.g. in malý město (small town), plamínek (little flame) and lítat (to fly), and a second native diphthong /ɛɪ̯/ occurs, usually in places where Standard Czech has /iː/, e.g. malej dům (small house), mlejn (mill), plejtvat (to waste), bejt (to be). In addition, a prothetic v- is added to most words beginning o-, such as votevřít vokno (to open the window).
Non-standard morphological features that are more or less common among all Common Czech speakers include:
Examples of declension (Standard Czech is added in italics for comparison):
mladý člověk – young man/person, mladí lidé – young people, mladý stát – young state, mladá žena – young woman, mladé zvíře – young animal
Apart from the Common Czech vernacular, there remain a variety of other Bohemian dialects, mostly in marginal rural areas. Dialect use began to weaken in the second half of the 20th century, and by the early 1990s regional dialect use was stigmatized, associated with the shrinking lower class and used in literature or other media for comedic effect. Increased travel and media availability to dialect-speaking populations has encouraged them to shift to (or add to their own dialect) Standard Czech.
The Czech Statistical Office in 2003 recognized the following Bohemian dialects:
The Czech dialects spoken in Moravia and Silesia are known as Moravian (moravština). In the Austro-Hungarian Empire, "Bohemian-Moravian-Slovak" was a language citizens could register as speaking (with German, Polish and several others). In the 2011 census, where respondents could optionally specify up to two first languages, 62,908 Czech citizens specified Moravian as their first language and 45,561 specified both Moravian and Czech.
Beginning in the sixteenth century, some varieties of Czech resembled Slovak; the southeastern Moravian dialects, in particular, are sometimes considered dialects of Slovak rather than Czech. These dialects form a continuum between the Czech and Slovak languages, using the same declension patterns for nouns and pronouns and the same verb conjugations as Slovak.
The Czech Statistical Office in 2003 recognized the following Moravian dialects:
In a 1964 textbook on Czech dialectology, Břetislav Koudela used the following sentence to highlight phonetic differences between dialects:
Czech and Slovak have been considered mutually intelligible; speakers of either language can communicate with greater ease than those of any other pair of West Slavic languages. Following the 1993 dissolution of Czechoslovakia, mutual intelligibility declined for younger speakers, probably because Czech speakers began to experience less exposure to Slovak and vice versa. A 2015 study involving participants with a mean age of around 23 nonetheless concluded that there remained a high degree of mutual intelligibility between the two languages. Grammatically, both languages share a common syntax.
One study showed that Czech and Slovak lexicons differed by 80 percent, but this high percentage was found to stem primarily from differing orthographies and slight inconsistencies in morphological formation; Slovak morphology is more regular (when changing from the nominative to the locative case, Praha becomes Praze in Czech and Prahe in Slovak). The two lexicons are generally considered similar, with most differences found in colloquial vocabulary and some scientific terminology. Slovak has slightly more borrowed words than Czech.
The similarities between Czech and Slovak led to the languages being considered a single language by a group of 19th-century scholars who called themselves "Czechoslavs" (Čechoslované), believing that the peoples were connected in a way which excluded German Bohemians and (to a lesser extent) Hungarians and other Slavs. During the First Czechoslovak Republic (1918–1938), although "Czechoslovak" was designated as the republic's official language, both Czech and Slovak written standards were used. Standard written Slovak was partially modeled on literary Czech, and Czech was preferred for some official functions in the Slovak half of the republic. Czech influence on Slovak was protested by Slovak scholars, and when Slovakia broke off from Czechoslovakia in 1938 as the Slovak State (which then aligned with Nazi Germany in World War II), literary Slovak was deliberately distanced from Czech. When the Axis powers lost the war and Czechoslovakia reformed, Slovak developed somewhat on its own (with Czech influence); during the Prague Spring of 1968, Slovak gained independence from (and equality with) Czech, due to the transformation of Czechoslovakia from a unitary state to a federation. Since the dissolution of Czechoslovakia in 1993, "Czechoslovak" has referred to improvised pidgins of the languages which have arisen from the decrease in mutual intelligibility.
Czech vocabulary derives primarily from Slavic, Baltic and other Indo-European roots. Although most verbs have Balto-Slavic origins, pronouns, prepositions and some verbs have wider, Indo-European roots. Some loanwords have been restructured by folk etymology to resemble native Czech words (e.g. hřbitov, "graveyard" and listina, "list").
Most Czech loanwords originated in one of two time periods. Earlier loanwords, primarily from German, Greek and Latin, arrived before the Czech National Revival. More recent loanwords derive primarily from English and French, and also from Hebrew, Arabic and Persian. Many Russian loanwords, principally animal names and naval terms, also exist in Czech.
Although older German loanwords were colloquial, recent borrowings from other languages are associated with high culture. During the nineteenth century, words with Greek and Latin roots were rejected in favor of those based on older Czech words and common Slavic roots; "music" is muzyka in Polish and музыка (muzyka) in Russian, but in Czech it is hudba. Some Czech words have been borrowed as loanwords into English and other languages—for example, robot (from robota, "labor") and polka (from polka, "Polish woman" or from "půlka" "half").
Article 1 of the Universal Declaration of Human Rights in Czech:
Article 1 of the Universal Declaration of Human Rights in English: | [
{
"paragraph_id": 0,
"text": "Czech (/tʃɛk/; čeština [ˈtʃɛʃcɪna]), historically also known as Bohemian (/boʊˈhiːmiən, bə-/; Latin: lingua Bohemica), is a West Slavic language of the Czech–Slovak group, written in Latin script. Spoken by over 10 million people, it serves as the official language of the Czech Republic. Czech is closely related to Slovak, to the point of high mutual intelligibility, as well as to Polish to a lesser degree. Czech is a fusional language with a rich system of morphology and relatively flexible word order. Its vocabulary has been extensively influenced by Latin and German.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The Czech–Slovak group developed within West Slavic in the high medieval period, and the standardization of Czech and Slovak within the Czech–Slovak dialect continuum emerged in the early modern period. In the later 18th to mid-19th century, the modern written standard became codified in the context of the Czech National Revival. The main non-standard variety, known as Common Czech, is based on the vernacular of Prague, but is now spoken as an interdialect throughout most of the Czech Republic. The Moravian dialects spoken in the eastern part of the country are also classified as Czech, although some of their eastern variants are closer to Slovak.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Czech has a moderately-sized phoneme inventory, comprising ten monophthongs, three diphthongs and 25 consonants (divided into \"hard\", \"neutral\" and \"soft\" categories). Words may contain complicated consonant clusters or lack vowels altogether. Czech has a raised alveolar trill, which is known to occur as a phoneme in only a few other languages, represented by the grapheme ř.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Czech is a member of the West Slavic sub-branch of the Slavic branch of the Indo-European language family. This branch includes Polish, Kashubian, Upper and Lower Sorbian and Slovak. Slovak is the most closely related language to Czech, followed by Polish and Silesian.",
"title": "Classification"
},
{
"paragraph_id": 4,
"text": "The West Slavic languages are spoken in Central Europe. Czech is distinguished from other West Slavic languages by a more-restricted distinction between \"hard\" and \"soft\" consonants (see Phonology below).",
"title": "Classification"
},
{
"paragraph_id": 5,
"text": "The term \"Old Czech\" is applied to the period predating the 16th century, with the earliest records of the high medieval period also classified as \"early Old Czech\", but the term \"Medieval Czech\" is also used. The function of the written language was initially performed by Old Slavonic written in Glagolitic, later by Latin written in Latin script.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "Around the 7th century, the Slavic expansion reached Central Europe, settling on the eastern fringes of the Frankish Empire. The West Slavic polity of Great Moravia formed by the 9th century. The Christianization of Bohemia took place during the 9th and 10th centuries. The diversification of the Czech-Slovak group within West Slavic began around that time, marked among other things by its use of the voiced velar fricative consonant (/ɣ/) and consistent stress on the first syllable.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "The Bohemian (Czech) language is first recorded in writing in glosses and short notes during the 12th to 13th centuries. Literary works written in Czech appear in the late 13th and early 14th century and administrative documents first appear towards the late 14th century. The first complete Bible translation, the Leskovec-Dresden Bible, also dates to this period. Old Czech texts, including poetry and cookbooks, were also produced outside universities.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "Literary activity becomes widespread in the early 15th century in the context of the Bohemian Reformation. Jan Hus contributed significantly to the standardization of Czech orthography, advocated for widespread literacy among Czech commoners (particularly in religion) and made early efforts to model written Czech after the spoken language.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "There was no standardization distinguishing between Czech and Slovak prior to the 15th century. In the 16th century, the division between Czech and Slovak becomes apparent, marking the confessional division between Lutheran Protestants in Slovakia using Czech orthography and Catholics, especially Slovak Jesuits, beginning to use a separate Slovak orthography based on Western Slovak dialects.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "The publication of the Kralice Bible between 1579 and 1593 (the first complete Czech translation of the Bible from the original languages) became very important for standardization of the Czech language in the following centuries as it was used as a model for the standard language.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "In 1615, the Bohemian diet tried to declare Czech to be the only official language of the kingdom. After the Bohemian Revolt (of predominantly Protestant aristocracy) which was defeated by the Habsburgs in 1620, the Protestant intellectuals had to leave the country. This emigration together with other consequences of the Thirty Years' War had a negative impact on the further use of the Czech language. In 1627, Czech and German became official languages of the Kingdom of Bohemia and in the 18th century German became dominant in Bohemia and Moravia, especially among the upper classes.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "The modern standard Czech language originates in standardization efforts of the 18th century. By then the language had developed a literary tradition, and since then it has changed little; journals from that period have no substantial differences from modern standard Czech, and contemporary Czechs can understand them with little difficulty. Sometime before the 18th century, the Czech language abandoned a distinction between phonemic /l/ and /ʎ/ which survives in Slovak.",
"title": "History"
},
{
"paragraph_id": 13,
"text": "With the beginning of the national revival of the mid-18th century, Czech historians began to emphasize their people's accomplishments from the 15th through the 17th centuries, rebelling against the Counter-Reformation (the Habsburg re-catholization efforts which had denigrated Czech and other non-Latin languages). Czech philologists studied sixteenth-century texts, advocating the return of the language to high culture. This period is known as the Czech National Revival (or Renaissance).",
"title": "History"
},
{
"paragraph_id": 14,
"text": "During the national revival, in 1809 linguist and historian Josef Dobrovský released a German-language grammar of Old Czech entitled Ausführliches Lehrgebäude der böhmischen Sprache ('Comprehensive Doctrine of the Bohemian Language'). Dobrovský had intended his book to be descriptive, and did not think Czech had a realistic chance of returning as a major language. However, Josef Jungmann and other revivalists used Dobrovský's book to advocate for a Czech linguistic revival. Changes during this time included spelling reform (notably, í in place of the former j and j in place of g), the use of t (rather than ti) to end infinitive verbs and the non-capitalization of nouns (which had been a late borrowing from German). These changes differentiated Czech from Slovak. Modern scholars disagree about whether the conservative revivalists were motivated by nationalism or considered contemporary spoken Czech unsuitable for formal, widespread use.",
"title": "History"
},
{
"paragraph_id": 15,
"text": "Adherence to historical patterns was later relaxed and standard Czech adopted a number of features from Common Czech (a widespread, informally used interdialectal variety), such as leaving some proper nouns undeclined. This has resulted in a relatively high level of homogeneity among all varieties of the language.",
"title": "History"
},
{
"paragraph_id": 16,
"text": "Czech is spoken by about 10 million residents of the Czech Republic. A Eurobarometer survey conducted from January to March 2012 found that the first language of 98 percent of Czech citizens was Czech, the third-highest proportion of a population in the European Union (behind Greece and Hungary).",
"title": "Geographic distribution"
},
{
"paragraph_id": 17,
"text": "As the official language of the Czech Republic (a member of the European Union since 2004), Czech is one of the EU's official languages and the 2012 Eurobarometer survey found that Czech was the foreign language most often used in Slovakia. Economist Jonathan van Parys collected data on language knowledge in Europe for the 2012 European Day of Languages. The five countries with the greatest use of Czech were the Czech Republic (98.77 percent), Slovakia (24.86 percent), Portugal (1.93 percent), Poland (0.98 percent) and Germany (0.47 percent).",
"title": "Geographic distribution"
},
{
"paragraph_id": 18,
"text": "Czech speakers in Slovakia primarily live in cities. Since it is a recognized minority language in Slovakia, Slovak citizens who speak only Czech may communicate with the government in their language to the extent that Slovak speakers in the Czech Republic may do so.",
"title": "Geographic distribution"
},
{
"paragraph_id": 19,
"text": "Immigration of Czechs from Europe to the United States occurred primarily from 1848 to 1914. Czech is a Less Commonly Taught Language in U.S. schools, and is taught at Czech heritage centers. Large communities of Czech Americans live in the states of Texas, Nebraska and Wisconsin. In the 2000 United States Census, Czech was reported as the commonest language spoken at home (besides English) in Valley, Butler and Saunders Counties, Nebraska and Republic County, Kansas. With the exception of Spanish (the non-English language most commonly spoken at home nationwide), Czech was the most common home language in more than a dozen additional counties in Nebraska, Kansas, Texas, North Dakota and Minnesota. As of 2009, 70,500 Americans spoke Czech as their first language (49th place nationwide, after Turkish and before Swedish).",
"title": "Geographic distribution"
},
{
"paragraph_id": 20,
"text": "Standard Czech contains ten basic vowel phonemes, and three diphthongs. The vowels are /a/, /ɛ/, /ɪ/, /o/, and /u/, and their long counterparts /aː/, /ɛː/, /iː/, /oː/ and /uː/. The diphthongs are /ou̯/, /au̯/ and /ɛu̯/; the last two are found only in loanwords such as auto \"car\" and euro \"euro\".",
"title": "Phonology"
},
{
"paragraph_id": 21,
"text": "In Czech orthography, the vowels are spelled as follows:",
"title": "Phonology"
},
{
"paragraph_id": 22,
"text": "The letter ⟨ě⟩ indicates that the previous consonant is palatalized (e.g. něco /ɲɛt͡so/). After a labial it represents /jɛ/ (e.g. běs /bjɛs/); but ⟨mě⟩ is pronounced /mɲɛ/, cf. měkký (/mɲɛkiː/).",
"title": "Phonology"
},
{
"paragraph_id": 23,
"text": "The consonant phonemes of Czech and their equivalent letters in Czech orthography are as follows:",
"title": "Phonology"
},
{
"paragraph_id": 24,
"text": "Czech consonants are categorized as \"hard\", \"neutral\", or \"soft\":",
"title": "Phonology"
},
{
"paragraph_id": 25,
"text": "Hard consonants may not be followed by i or í in writing, or soft ones by y or ý (except in loanwords such as kilogram). Neutral consonants may take either character. Hard consonants are sometimes known as \"strong\", and soft ones as \"weak\". This distinction is also relevant to the declension patterns of nouns, which vary according to whether the final consonant of the noun stem is hard or soft.",
"title": "Phonology"
},
{
"paragraph_id": 26,
"text": "Voiced consonants with unvoiced counterparts are unvoiced at the end of a word before a pause, and in consonant clusters voicing assimilation occurs, which matches voicing to the following consonant. The unvoiced counterpart of /ɦ/ is /x/.",
"title": "Phonology"
},
{
"paragraph_id": 27,
"text": "The phoneme represented by the letter ř (capital Ř) is very rare among languages and often claimed to be unique to Czech, though it also occurs in some dialects of Kashubian, and formerly occurred in Polish. It represents the raised alveolar non-sonorant trill (IPA: [r̝]), a sound somewhere between Czech r and ž (example: \"řeka\" (river)), and is present in Dvořák. In unvoiced environments, /r̝/ is realized as its voiceless allophone [r̝̊], a sound somewhere between Czech r and š.",
"title": "Phonology"
},
{
"paragraph_id": 28,
"text": "The consonants /r/, /l/, and /m/ can be syllabic, acting as syllable nuclei in place of a vowel. Strč prst skrz krk (\"Stick [your] finger through [your] throat\") is a well-known Czech tongue twister using syllabic consonants but no vowels.",
"title": "Phonology"
},
{
"paragraph_id": 29,
"text": "Each word has primary stress on its first syllable, except for enclitics (minor, monosyllabic, unstressed syllables). In all words of more than two syllables, every odd-numbered syllable receives secondary stress. Stress is unrelated to vowel length; both long and short vowels can be stressed or unstressed. Vowels are never reduced in tone (e.g. to schwa sounds) when unstressed. When a noun is preceded by a monosyllabic preposition, the stress usually moves to the preposition, e.g. do Prahy \"to Prague\".",
"title": "Phonology"
},
{
"paragraph_id": 30,
"text": "Czech grammar, like that of other Slavic languages, is fusional; its nouns, verbs, and adjectives are inflected by phonological processes to modify their meanings and grammatical functions, and the easily separable affixes characteristic of agglutinative languages are limited. Czech inflects for case, gender and number in nouns and tense, aspect, mood, person and subject number and gender in verbs.",
"title": "Grammar"
},
{
"paragraph_id": 31,
"text": "Parts of speech include adjectives, adverbs, numbers, interrogative words, prepositions, conjunctions and interjections. Adverbs are primarily formed from adjectives by taking the final ý or í of the base form and replacing it with e, ě, y, or o. Negative statements are formed by adding the affix ne- to the main verb of a clause, with one exception: je (he, she or it is) becomes není.",
"title": "Grammar"
},
{
"paragraph_id": 32,
"text": "Because Czech uses grammatical case to convey word function in a sentence (instead of relying on word order, as English does), its word order is flexible. As a pro-drop language, in Czech an intransitive sentence can consist of only a verb; information about its subject is encoded in the verb. Enclitics (primarily auxiliary verbs and pronouns) appear in the second syntactic slot of a sentence, after the first stressed unit. The first slot can contain a subject or object, a main form of a verb, an adverb, or a conjunction (except for the light conjunctions a, \"and\", i, \"and even\" or ale, \"but\").",
"title": "Grammar"
},
{
"paragraph_id": 33,
"text": "Czech syntax has a subject–verb–object sentence structure. In practice, however, word order is flexible and used to distinguish topic and focus, with the topic or theme (known referents) preceding the focus or rheme (new information) in a sentence; Czech has therefore been described as a topic-prominent language. Although Czech has a periphrastic passive construction (like English), in colloquial style, word-order changes frequently replace the passive voice. For example, to change \"Peter killed Paul\" to \"Paul was killed by Peter\" the order of subject and object is inverted: Petr zabil Pavla (\"Peter killed Paul\") becomes \"Paul, Peter killed\" (Pavla zabil Petr). Pavla is in the accusative case, the grammatical object of the verb.",
"title": "Grammar"
},
{
"paragraph_id": 34,
"text": "A word at the end of a clause is typically emphasized, unless an upward intonation indicates that the sentence is a question:",
"title": "Grammar"
},
{
"paragraph_id": 35,
"text": "In parts of Bohemia (including Prague), questions such as Jí pes bagetu? without an interrogative word (such as co, \"what\" or kdo, \"who\") are intoned in a slow rise from low to high, quickly dropping to low on the last word or phrase.",
"title": "Grammar"
},
{
"paragraph_id": 36,
"text": "In modern Czech syntax, adjectives precede nouns, with few exceptions. Relative clauses are introduced by relativizers such as the adjective který, analogous to the English relative pronouns \"which\", \"that\" and \"who\"/\"whom\". As with other adjectives, it agrees with its associated noun in gender, number and case. Relative clauses follow the noun they modify. The following is a glossed example:",
"title": "Grammar"
},
{
"paragraph_id": 37,
"text": "Chc-i",
"title": "Grammar"
},
{
"paragraph_id": 38,
"text": "want-1SG",
"title": "Grammar"
},
{
"paragraph_id": 39,
"text": "navštív-it",
"title": "Grammar"
},
{
"paragraph_id": 40,
"text": "visit-INF",
"title": "Grammar"
},
{
"paragraph_id": 41,
"text": "universit-u,",
"title": "Grammar"
},
{
"paragraph_id": 42,
"text": "university-SG.ACC,",
"title": "Grammar"
},
{
"paragraph_id": 43,
"text": "na",
"title": "Grammar"
},
{
"paragraph_id": 44,
"text": "on",
"title": "Grammar"
},
{
"paragraph_id": 45,
"text": "kter-ou",
"title": "Grammar"
},
{
"paragraph_id": 46,
"text": "which-SG.F.ACC",
"title": "Grammar"
},
{
"paragraph_id": 47,
"text": "chod-í",
"title": "Grammar"
},
{
"paragraph_id": 48,
"text": "attend-3SG",
"title": "Grammar"
},
{
"paragraph_id": 49,
"text": "Jan.",
"title": "Grammar"
},
{
"paragraph_id": 50,
"text": "John.SG.NOM",
"title": "Grammar"
},
{
"paragraph_id": 51,
"text": "Chc-i navštív-it universit-u, na kter-ou chod-í Jan.",
"title": "Grammar"
},
{
"paragraph_id": 52,
"text": "want-1SG visit-INF university-SG.ACC, on which-SG.F.ACC attend-3SG John.SG.NOM",
"title": "Grammar"
},
{
"paragraph_id": 53,
"text": "I want to visit the university that John attends.",
"title": "Grammar"
},
{
"paragraph_id": 54,
"text": "In Czech, nouns and adjectives are declined into one of seven grammatical cases which indicate their function in a sentence, two numbers (singular and plural) and three genders (masculine, feminine and neuter). The masculine gender is further divided into animate and inanimate classes.",
"title": "Grammar"
},
{
"paragraph_id": 55,
"text": "A nominative–accusative language, Czech marks subject nouns of transitive and intransitive verbs in the nominative case, which is the form found in dictionaries, and direct objects of transitive verbs are declined in the accusative case. The vocative case is used to address people. The remaining cases (genitive, dative, locative and instrumental) indicate semantic relationships, such as noun adjuncts (genitive), indirect objects (dative), or agents in passive constructions (instrumental). Additionally prepositions and some verbs require their complements to be declined in a certain case. The locative case is only used after prepositions. An adjective's case agrees with that of the noun it modifies. When Czech children learn their language's declension patterns, the cases are referred to by number:",
"title": "Grammar"
},
{
"paragraph_id": 56,
"text": "Some prepositions require the nouns they modify to take a particular case. The cases assigned by each preposition are based on the physical (or metaphorical) direction, or location, conveyed by it. For example, od (from, away from) and z (out of, off) assign the genitive case. Other prepositions take one of several cases, with their meaning dependent on the case; na means \"onto\" or \"for\" with the accusative case, but \"on\" with the locative.",
"title": "Grammar"
},
{
"paragraph_id": 57,
"text": "This is a glossed example of a sentence using several cases:",
"title": "Grammar"
},
{
"paragraph_id": 58,
"text": "Nes-l",
"title": "Grammar"
},
{
"paragraph_id": 59,
"text": "carry-SG.M.PST",
"title": "Grammar"
},
{
"paragraph_id": 60,
"text": "js-em",
"title": "Grammar"
},
{
"paragraph_id": 61,
"text": "be-1.SG",
"title": "Grammar"
},
{
"paragraph_id": 62,
"text": "krabic-i",
"title": "Grammar"
},
{
"paragraph_id": 63,
"text": "box-SG.ACC",
"title": "Grammar"
},
{
"paragraph_id": 64,
"text": "do",
"title": "Grammar"
},
{
"paragraph_id": 65,
"text": "into",
"title": "Grammar"
},
{
"paragraph_id": 66,
"text": "dom-u",
"title": "Grammar"
},
{
"paragraph_id": 67,
"text": "house-SG.GEN",
"title": "Grammar"
},
{
"paragraph_id": 68,
"text": "se",
"title": "Grammar"
},
{
"paragraph_id": 69,
"text": "with",
"title": "Grammar"
},
{
"paragraph_id": 70,
"text": "sv-ým",
"title": "Grammar"
},
{
"paragraph_id": 71,
"text": "own-SG.INS",
"title": "Grammar"
},
{
"paragraph_id": 72,
"text": "přítel-em.",
"title": "Grammar"
},
{
"paragraph_id": 73,
"text": "friend-SG.INS",
"title": "Grammar"
},
{
"paragraph_id": 74,
"text": "Nes-l js-em krabic-i do dom-u se sv-ým přítel-em.",
"title": "Grammar"
},
{
"paragraph_id": 75,
"text": "carry-SG.M.PST be-1.SG box-SG.ACC into house-SG.GEN with own-SG.INS friend-SG.INS",
"title": "Grammar"
},
{
"paragraph_id": 76,
"text": "I carried the box into the house with my friend.",
"title": "Grammar"
},
{
"paragraph_id": 77,
"text": "Czech distinguishes three genders—masculine, feminine, and neuter—and the masculine gender is subdivided into animate and inanimate. With few exceptions, feminine nouns in the nominative case end in -a, -e, or a consonant; neuter nouns in -o, -e, or -í, and masculine nouns in a consonant. Adjectives, participles, most pronouns, and the numbers \"one\" and \"two\" are marked for gender and agree with the gender of the noun they modify or refer to. Past tense verbs are also marked for gender, agreeing with the gender of the subject, e.g. dělal (he did, or made); dělala (she did, or made) and dělalo (it did, or made). Gender also plays a semantic role; most nouns that describe people and animals, including personal names, have separate masculine and feminine forms which are normally formed by adding a suffix to the stem, for example Čech (Czech man) has the feminine form Češka (Czech woman).",
"title": "Grammar"
},
{
"paragraph_id": 78,
"text": "Nouns of different genders follow different declension patterns. Examples of declension patterns for noun phrases of various genders follow:",
"title": "Grammar"
},
{
"paragraph_id": 79,
"text": "Nouns are also inflected for number, distinguishing between singular and plural. Typical of a Slavic language, Czech cardinal numbers one through four allow the nouns and adjectives they modify to take any case, but numbers over five require subject and direct object noun phrases to be declined in the genitive plural instead of the nominative or accusative, and when used as subjects these phrases take singular verbs. For example:",
"title": "Grammar"
},
{
"paragraph_id": 80,
"text": "Numbers decline for case, and the numbers one and two are also inflected for gender. Numbers one through five are shown below as examples. The number one has declension patterns identical to those of the demonstrative pronoun ten.",
"title": "Grammar"
},
{
"paragraph_id": 81,
"text": "Although Czech's grammatical numbers are singular and plural, several residuals of dual forms remain, such as the words dva (\"two\") and oba (\"both\"), which decline the same way. Some nouns for paired body parts use a historical dual form to express plural in some cases: ruka (hand)—ruce (nominative); noha (leg)—nohama (instrumental), nohou (genitive/locative); oko (eye)—oči, and ucho (ear)—uši. While two of these nouns are neuter in their singular forms, all plural forms are considered feminine; their gender is relevant to their associated adjectives and verbs. These forms are plural semantically, used for any non-singular count, as in mezi čtyřma očima (face to face, lit. among four eyes). The plural number paradigms of these nouns are a mixture of historical dual and plural forms. For example, nohy (legs; nominative/accusative) is a standard plural form of this type of noun.",
"title": "Grammar"
},
{
"paragraph_id": 82,
"text": "Czech verbs agree with their subjects in person (first, second or third), number (singular or plural), and in constructions involving participles, which includes the past tense, also in gender. They are conjugated for tense (past, present or future) and mood (indicative, imperative or conditional). For example, the conjugated verb mluvíme (we speak) is in the present tense and first-person plural; it is distinguished from other conjugations of the infinitive mluvit by its ending, -íme. The infinitive form of Czech verbs ends in -t (archaically, -ti or -ci). It is the form found in dictionaries and the form that follows auxiliary verbs (for example, můžu tě slyšet—\"I can hear you\").",
"title": "Grammar"
},
{
"paragraph_id": 83,
"text": "Typical of Slavic languages, Czech marks its verbs for one of two grammatical aspects: perfective and imperfective. Most verbs are part of inflected aspect pairs—for example, koupit (perfective) and kupovat (imperfective). Although the verbs' meaning is similar, in perfective verbs the action is completed and in imperfective verbs it is ongoing or repeated. This is distinct from past and present tense. Any verb of either aspect can be conjugated into either the past or present tense, but the future tense is only used with imperfective verbs. Aspect describes the state of the action at the time specified by the tense.",
"title": "Grammar"
},
{
"paragraph_id": 84,
"text": "The verbs of most aspect pairs differ in one of two ways: by prefix or by suffix. In prefix pairs, the perfective verb has an added prefix—for example, the imperfective psát (to write, to be writing) compared with the perfective napsat (to write down). The most common prefixes are na-, o-, po-, s-, u-, vy-, z- and za-. In suffix pairs, a different infinitive ending is added to the perfective stem; for example, the perfective verbs koupit (to buy) and prodat (to sell) have the imperfective forms kupovat and prodávat. Imperfective verbs may undergo further morphology to make other imperfective verbs (iterative and frequentative forms), denoting repeated or regular action. The verb jít (to go) has the iterative form chodit (to go regularly) and the frequentative form chodívat (to go occasionally; to tend to go).",
"title": "Grammar"
},
{
"paragraph_id": 85,
"text": "Many verbs have only one aspect, and verbs describing continual states of being—být (to be), chtít (to want), moct (to be able to), ležet (to lie down, to be lying down)—have no perfective form. Conversely, verbs describing immediate states of change—for example, otěhotnět (to become pregnant) and nadchnout se (to become enthusiastic)—have no imperfective aspect.",
"title": "Grammar"
},
{
"paragraph_id": 86,
"text": "The present tense in Czech is formed by adding an ending that agrees with the person and number of the subject at the end of the verb stem. As Czech is a null-subject language, the subject pronoun can be omitted unless it is needed for clarity. The past tense is formed using a participle which ends in -l and a further ending which agrees with the gender and number of the subject. For the first and second persons, the auxiliary verb být conjugated in the present tense is added.",
"title": "Grammar"
},
{
"paragraph_id": 87,
"text": "In some contexts, the present tense of perfective verbs (which differs from the English present perfect) implies future action; in others, it connotes habitual action. The perfective present is used to refer to completion of actions in the future and is distinguished from the imperfective future tense, which refers to actions that will be ongoing in the future. The future tense is regularly formed using the future conjugation of být (as shown in the table on the left) and the infinitive of an imperfective verb, for example, budu jíst—\"I will eat\" or \"I will be eating\". Where budu has a noun or adjective complement it means \"I will be\", for example, budu šťastný (I will be happy). Some verbs of movement form their future tense by adding the prefix po- to the present tense forms instead, e.g. jedu (\"I go\") > pojedu (\"I will go\").",
"title": "Grammar"
},
{
"paragraph_id": 88,
"text": "Czech verbs have three grammatical moods: indicative, imperative and conditional. The imperative mood is formed by adding specific endings for each of three person–number categories: -Ø/-i/-ej for second-person singular, -te/-ete/-ejte for second-person plural and -me/-eme/-ejme for first-person plural. Imperatives are usually expressed using perfective verbs if positive and imperfective verbs if negative. The conditional mood is formed with a conditional auxiliary verb after the participle ending in -l which is used to form the past tense. This mood indicates hypothetical events and can also be used to express wishes.",
"title": "Grammar"
},
{
"paragraph_id": 89,
"text": "Most Czech verbs fall into one of five classes, which determine their conjugation patterns. The future tense of být would be classified as a Class I verb because of its endings. Examples of the present tense of each class and some common irregular verbs follow in the tables below:",
"title": "Grammar"
},
{
"paragraph_id": 90,
"text": "Czech has one of the most phonemic orthographies of all European languages. Its alphabet contains 42 graphemes, most of which correspond to individual phonemes, and only contains only one digraph: ch, which follows h in the alphabet. The characters q, w and x appear only in foreign words. The háček (ˇ) is used with certain letters to form new characters: š, ž, and č, as well as ň, ě, ř, ť, and ď (the latter five uncommon outside Czech). The last two letters are sometimes written with a comma above (ʼ, an abbreviated háček) because of their height. Czech orthography has influenced the orthographies of other Balto-Slavic languages and some of its characters have been adopted for transliteration of Cyrillic.",
"title": "Orthography"
},
{
"paragraph_id": 91,
"text": "Czech orthography reflects vowel length; long vowels are indicated by an acute accent or, in the case of the character ů, a ring. Long u is usually written ú at the beginning of a word or morpheme (úroda, neúrodný) and ů elsewhere, except for loanwords (skútr) or onomatopoeia (bú). Long vowels and ě are not considered separate letters in the alphabetical order. The character ó exists only in loanwords and onomatopoeia.",
"title": "Orthography"
},
{
"paragraph_id": 92,
"text": "Czech typographical features not associated with phonetics generally resemble those of most European languages that use the Latin script, including English. Proper nouns, honorifics, and the first letters of quotations are capitalized, and punctuation is typical of other Latin European languages. Ordinal numbers (1st) use a point, as in German (1.). The Czech language uses a decimal comma instead of a decimal point. When writing a long number, spaces between every three digits, including those in decimal places, may be used for better orientation in handwritten texts. The number 1,234,567.89101 may be written as 1234567,89101 or 1 234 567,891 01. In proper noun phrases (except personal and settlement names), only the first word and proper nouns inside such phrases are capitalized (Pražský hrad, Prague Castle).",
"title": "Orthography"
},
{
"paragraph_id": 93,
"text": "The modern literary standard and prestige variety, known as \"Standard Czech\" (spisovná čeština) is based on the standardization during the Czech National Revival in the 1830s, significantly influenced by Josef Jungmann's Czech–German dictionary published during 1834–1839. Jungmann used vocabulary of the Bible of Kralice (1579–1613) period and of the language used by his contemporaries. He borrowed words not present in Czech from other Slavic languages or created neologisms. Standard Czech is the formal register of the language which is used in official documents, formal literature, newspaper articles, education and occasionally public speeches. It is codified by the Czech Language Institute, who publish occasional reforms to the codification. The most recent reform took place in 1993. The term hovorová čeština (lit. \"Colloquial Czech\") is sometimes used to refer to the spoken variety of standard Czech.",
"title": "Varieties"
},
{
"paragraph_id": 94,
"text": "The most widely spoken vernacular form of the language is called \"Common Czech\" (obecná čeština), an interdialect influenced by spoken Standard Czech and the Central Bohemian dialects of the Prague region. Other Bohemian regional dialects have become marginalized, while Moravian dialects remain more widespread and diverse, with a political movement for Moravian linguistic revival active since the 1990s.",
"title": "Varieties"
},
{
"paragraph_id": 95,
"text": "These varieties of the language (Standard Czech, spoken/colloquial Standard Czech, Common Czech, and regional dialects) form a stylistic continuum, in which contact between varieties of a similar prestige influences change within them.",
"title": "Varieties"
},
{
"paragraph_id": 96,
"text": "The main Czech vernacular, spoken primarily in Bohemia including the capital Prague, is known as Common Czech (obecná čeština). This is an academic distinction; most Czechs are unaware of the term or associate it with deformed or \"incorrect\" Czech. Compared to Standard Czech, Common Czech is characterized by simpler inflection patterns and differences in sound distribution.",
"title": "Varieties"
},
{
"paragraph_id": 97,
"text": "Common Czech is distinguished from spoken/colloquial Standard Czech (hovorová čeština), which is a stylistic variety within standard Czech. Tomasz Kamusella defines the spoken variety of Standard Czech as a compromise between Common Czech and the written standard, while Miroslav Komárek calls Common Czech an intersection of spoken Standard Czech and regional dialects.",
"title": "Varieties"
},
{
"paragraph_id": 98,
"text": "Common Czech has become ubiquitous in most parts of the Czech Republic since the later 20th century. It is usually defined as an interdialect used in common speech in Bohemia and western parts of Moravia (by about two thirds of all inhabitants of the Czech Republic). Common Czech is not codified, but some of its elements have become adopted in the written standard. Since the second half of the 20th century, Common Czech elements have also been spreading to regions previously unaffected, as a consequence of media influence. Standard Czech is still the norm for politicians, businesspeople and other Czechs in formal situations, but Common Czech is gaining ground in journalism and the mass media. The colloquial form of Standard Czech finds limited use in daily communication due to the expansion of the Common Czech interdialect. It is sometimes defined as a theoretical construct rather than an actual tool of colloquial communication, since in casual contexts, the non-standard interdialect is preferred.",
"title": "Varieties"
},
{
"paragraph_id": 99,
"text": "Common Czech phonology is based on that of the Central Bohemian dialect group, which has a slightly different set of vowel phonemes to Standard Czech. The phoneme /ɛː/ is peripheral and usually merges with /iː/, e.g. in malý město (small town), plamínek (little flame) and lítat (to fly), and a second native diphthong /ɛɪ̯/ occurs, usually in places where Standard Czech has /iː/, e.g. malej dům (small house), mlejn (mill), plejtvat (to waste), bejt (to be). In addition, a prothetic v- is added to most words beginning o-, such as votevřít vokno (to open the window).",
"title": "Varieties"
},
{
"paragraph_id": 100,
"text": "Non-standard morphological features that are more or less common among all Common Czech speakers include:",
"title": "Varieties"
},
{
"paragraph_id": 101,
"text": "Examples of declension (Standard Czech is added in italics for comparison):",
"title": "Varieties"
},
{
"paragraph_id": 102,
"text": "mladý člověk – young man/person, mladí lidé – young people, mladý stát – young state, mladá žena – young woman, mladé zvíře – young animal",
"title": "Varieties"
},
{
"paragraph_id": 103,
"text": "Apart from the Common Czech vernacular, there remain a variety of other Bohemian dialects, mostly in marginal rural areas. Dialect use began to weaken in the second half of the 20th century, and by the early 1990s regional dialect use was stigmatized, associated with the shrinking lower class and used in literature or other media for comedic effect. Increased travel and media availability to dialect-speaking populations has encouraged them to shift to (or add to their own dialect) Standard Czech.",
"title": "Varieties"
},
{
"paragraph_id": 104,
"text": "The Czech Statistical Office in 2003 recognized the following Bohemian dialects:",
"title": "Varieties"
},
{
"paragraph_id": 105,
"text": "The Czech dialects spoken in Moravia and Silesia are known as Moravian (moravština). In the Austro-Hungarian Empire, \"Bohemian-Moravian-Slovak\" was a language citizens could register as speaking (with German, Polish and several others). In the 2011 census, where respondents could optionally specify up to two first languages, 62,908 Czech citizens specified Moravian as their first language and 45,561 specified both Moravian and Czech.",
"title": "Varieties"
},
{
"paragraph_id": 106,
"text": "Beginning in the sixteenth century, some varieties of Czech resembled Slovak; the southeastern Moravian dialects, in particular, are sometimes considered dialects of Slovak rather than Czech. These dialects form a continuum between the Czech and Slovak languages, using the same declension patterns for nouns and pronouns and the same verb conjugations as Slovak.",
"title": "Varieties"
},
{
"paragraph_id": 107,
"text": "The Czech Statistical Office in 2003 recognized the following Moravian dialects:",
"title": "Varieties"
},
{
"paragraph_id": 108,
"text": "In a 1964 textbook on Czech dialectology, Břetislav Koudela used the following sentence to highlight phonetic differences between dialects:",
"title": "Varieties"
},
{
"paragraph_id": 109,
"text": "Czech and Slovak have been considered mutually intelligible; speakers of either language can communicate with greater ease than those of any other pair of West Slavic languages. Following the 1993 dissolution of Czechoslovakia, mutual intelligibility declined for younger speakers, probably because Czech speakers began to experience less exposure to Slovak and vice versa. A 2015 study involving participants with a mean age of around 23 nonetheless concluded that there remained a high degree of mutual intelligibility between the two languages. Grammatically, both languages share a common syntax.",
"title": "Varieties"
},
{
"paragraph_id": 110,
"text": "One study showed that Czech and Slovak lexicons differed by 80 percent, but this high percentage was found to stem primarily from differing orthographies and slight inconsistencies in morphological formation; Slovak morphology is more regular (when changing from the nominative to the locative case, Praha becomes Praze in Czech and Prahe in Slovak). The two lexicons are generally considered similar, with most differences found in colloquial vocabulary and some scientific terminology. Slovak has slightly more borrowed words than Czech.",
"title": "Varieties"
},
{
"paragraph_id": 111,
"text": "The similarities between Czech and Slovak led to the languages being considered a single language by a group of 19th-century scholars who called themselves \"Czechoslavs\" (Čechoslované), believing that the peoples were connected in a way which excluded German Bohemians and (to a lesser extent) Hungarians and other Slavs. During the First Czechoslovak Republic (1918–1938), although \"Czechoslovak\" was designated as the republic's official language, both Czech and Slovak written standards were used. Standard written Slovak was partially modeled on literary Czech, and Czech was preferred for some official functions in the Slovak half of the republic. Czech influence on Slovak was protested by Slovak scholars, and when Slovakia broke off from Czechoslovakia in 1938 as the Slovak State (which then aligned with Nazi Germany in World War II), literary Slovak was deliberately distanced from Czech. When the Axis powers lost the war and Czechoslovakia reformed, Slovak developed somewhat on its own (with Czech influence); during the Prague Spring of 1968, Slovak gained independence from (and equality with) Czech, due to the transformation of Czechoslovakia from a unitary state to a federation. Since the dissolution of Czechoslovakia in 1993, \"Czechoslovak\" has referred to improvised pidgins of the languages which have arisen from the decrease in mutual intelligibility.",
"title": "Varieties"
},
{
"paragraph_id": 112,
"text": "Czech vocabulary derives primarily from Slavic, Baltic and other Indo-European roots. Although most verbs have Balto-Slavic origins, pronouns, prepositions and some verbs have wider, Indo-European roots. Some loanwords have been restructured by folk etymology to resemble native Czech words (e.g. hřbitov, \"graveyard\" and listina, \"list\").",
"title": "Vocabulary"
},
{
"paragraph_id": 113,
"text": "Most Czech loanwords originated in one of two time periods. Earlier loanwords, primarily from German, Greek and Latin, arrived before the Czech National Revival. More recent loanwords derive primarily from English and French, and also from Hebrew, Arabic and Persian. Many Russian loanwords, principally animal names and naval terms, also exist in Czech.",
"title": "Vocabulary"
},
{
"paragraph_id": 114,
"text": "Although older German loanwords were colloquial, recent borrowings from other languages are associated with high culture. During the nineteenth century, words with Greek and Latin roots were rejected in favor of those based on older Czech words and common Slavic roots; \"music\" is muzyka in Polish and музыка (muzyka) in Russian, but in Czech it is hudba. Some Czech words have been borrowed as loanwords into English and other languages—for example, robot (from robota, \"labor\") and polka (from polka, \"Polish woman\" or from \"půlka\" \"half\").",
"title": "Vocabulary"
},
{
"paragraph_id": 115,
"text": "Article 1 of the Universal Declaration of Human Rights in Czech:",
"title": "Example text"
},
{
"paragraph_id": 116,
"text": "Article 1 of the Universal Declaration of Human Rights in English:",
"title": "Example text"
},
{
"paragraph_id": 117,
"text": "",
"title": "External links"
}
] | Czech, historically also known as Bohemian, is a West Slavic language of the Czech–Slovak group, written in Latin script. Spoken by over 10 million people, it serves as the official language of the Czech Republic. Czech is closely related to Slovak, to the point of high mutual intelligibility, as well as to Polish to a lesser degree. Czech is a fusional language with a rich system of morphology and relatively flexible word order. Its vocabulary has been extensively influenced by Latin and German. The Czech–Slovak group developed within West Slavic in the high medieval period, and the standardization of Czech and Slovak within the Czech–Slovak dialect continuum emerged in the early modern period. In the later 18th to mid-19th century, the modern written standard became codified in the context of the Czech National Revival. The main non-standard variety, known as Common Czech, is based on the vernacular of Prague, but is now spoken as an interdialect throughout most of the Czech Republic. The Moravian dialects spoken in the eastern part of the country are also classified as Czech, although some of their eastern variants are closer to Slovak. Czech has a moderately-sized phoneme inventory, comprising ten monophthongs, three diphthongs and 25 consonants. Words may contain complicated consonant clusters or lack vowels altogether. Czech has a raised alveolar trill, which is known to occur as a phoneme in only a few other languages, represented by the grapheme ř. | 2001-09-14T20:07:16Z | 2023-12-31T15:04:36Z | [
"Template:Refn",
"Template:Portal",
"Template:Languages of the Czech Republic",
"Template:IPA-cs",
"Template:Col-end",
"Template:Cite book",
"Template:Small",
"Template:Cite news",
"Template:Commons category",
"Template:See also",
"Template:As of",
"Template:Angle bracket",
"Template:Col-begin",
"Template:Cite journal",
"Template:Portal bar",
"Template:Good article",
"Template:IPAc-en",
"Template:IPAlink",
"Template:InterWiki",
"Template:Wikibooks",
"Template:Languages of Slovakia",
"Template:Main",
"Template:IPA",
"Template:Cite dictionary",
"Template:Col-2",
"Template:Reflist",
"Template:Cite web",
"Template:Wiktionary category",
"Template:NIE poster",
"Template:Short description",
"Template:Infobox language",
"Template:Further",
"Template:In lang",
"Template:Czech Republic topics",
"Template:Silesia topics",
"Template:Prone to spam",
"Template:Authority control",
"Template:Sfn",
"Template:Interlinear",
"Template:Wikivoyage",
"Template:Harvnb",
"Template:Slavic languages",
"Template:Lang",
"Template:Lang-la",
"Template:Audio"
] | https://en.wikipedia.org/wiki/Czech_language |
6,344 | Capsid | A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The proteins making up the capsid are called capsid proteins or viral coat proteins (VCP). The capsid and inner genome is called the nucleocapsid.
Capsids are broadly classified according to their structure. The majority of the viruses have capsids with either helical or icosahedral structure. Some viruses, such as bacteriophages, have developed more complicated structures due to constraints of elasticity and electrostatics. The icosahedral shape, which has 20 equilateral triangular faces, approximates a sphere, while the helical shape resembles the shape of a spring, taking the space of a cylinder but not being a cylinder itself. The capsid faces may consist of one or more proteins. For example, the foot-and-mouth disease virus capsid has faces consisting of three proteins named VP1–3.
Some viruses are enveloped, meaning that the capsid is coated with a lipid membrane known as the viral envelope. The envelope is acquired by the capsid from an intracellular membrane in the virus' host; examples include the inner nuclear membrane, the Golgi membrane, and the cell's outer membrane.
Once the virus has infected a cell and begins replicating itself, new capsid subunits are synthesized using the protein biosynthesis mechanism of the cell. In some viruses, including those with helical capsids and especially those with RNA genomes, the capsid proteins co-assemble with their genomes. In other viruses, especially more complex viruses with double-stranded DNA genomes, the capsid proteins assemble into empty precursor procapsids that include a specialized portal structure at one vertex. Through this portal, viral DNA is translocated into the capsid.
Structural analyses of major capsid protein (MCP) architectures have been used to categorise viruses into lineages. For example, the bacteriophage PRD1, the algal virus Paramecium bursaria Chlorella virus-1 (PBCV-1), mimivirus and the mammalian adenovirus have been placed in the same lineage, whereas tailed, double-stranded DNA bacteriophages (Caudovirales) and herpesvirus belong to a second lineage.
The icosahedral structure is extremely common among viruses. The icosahedron consists of 20 triangular faces delimited by 12 fivefold vertexes and consists of 60 asymmetric units. Thus, an icosahedral virus is made of 60N protein subunits. The number and arrangement of capsomeres in an icosahedral capsid can be classified using the "quasi-equivalence principle" proposed by Donald Caspar and Aaron Klug. Like the Goldberg polyhedra, an icosahedral structure can be regarded as being constructed from pentamers and hexamers. The structures can be indexed by two integers h and k, with h ≥ 1 {\displaystyle h\geq 1} and k ≥ 0 {\displaystyle k\geq 0} ; the structure can be thought of as taking h steps from the edge of a pentamer, turning 60 degrees counterclockwise, then taking k steps to get to the next pentamer. The triangulation number T for the capsid is defined as:
In this scheme, icosahedral capsids contain 12 pentamers plus 10(T − 1) hexamers. The T-number is representative of the size and complexity of the capsids. Geometric examples for many values of h, k, and T can be found at List of geodesic polyhedra and Goldberg polyhedra.
Many exceptions to this rule exist: For example, the polyomaviruses and papillomaviruses have pentamers instead of hexamers in hexavalent positions on a quasi T = 7 lattice. Members of the double-stranded RNA virus lineage, including reovirus, rotavirus and bacteriophage φ6 have capsids built of 120 copies of capsid protein, corresponding to a T = 2 capsid, or arguably a T = 1 capsid with a dimer in the asymmetric unit. Similarly, many small viruses have a pseudo T = 3 (or P = 3) capsid, which is organized according to a T = 3 lattice, but with distinct polypeptides occupying the three quasi-equivalent positions
T-numbers can be represented in different ways, for example T = 1 can only be represented as an icosahedron or a dodecahedron and, depending on the type of quasi-symmetry, T = 3 can be presented as a truncated dodecahedron, an icosidodecahedron, or a truncated icosahedron and their respective duals a triakis icosahedron, a rhombic triacontahedron, or a pentakis dodecahedron.
An elongated icosahedron is a common shape for the heads of bacteriophages. Such a structure is composed of a cylinder with a cap at either end. The cylinder is composed of 10 elongated triangular faces. The Q number (or Tmid), which can be any positive integer, specifies the number of triangles, composed of asymmetric subunits, that make up the 10 triangles of the cylinder. The caps are classified by the T (or Tend) number.
The bacterium E. coli is the host for bacteriophage T4 that has a prolate head structure. The bacteriophage encoded gp31 protein appears to be functionally homologous to E. coli chaperone protein GroES and able to substitute for it in the assembly of bacteriophage T4 virions during infection. Like GroES, gp31 forms a stable complex with GroEL chaperonin that is absolutely necessary for the folding and assembly in vivo of the bacteriophage T4 major capsid protein gp23.
Many rod-shaped and filamentous plant viruses have capsids with helical symmetry. The helical structure can be described as a set of n 1-D molecular helices related by an n-fold axial symmetry. The helical transformation are classified into two categories: one-dimensional and two-dimensional helical systems. Creating an entire helical structure relies on a set of translational and rotational matrices which are coded in the protein data bank. Helical symmetry is given by the formula P = μ x ρ, where μ is the number of structural units per turn of the helix, ρ is the axial rise per unit and P is the pitch of the helix. The structure is said to be open due to the characteristic that any volume can be enclosed by varying the length of the helix. The most understood helical virus is the tobacco mosaic virus. The virus is a single molecule of (+) strand RNA. Each coat protein on the interior of the helix bind three nucleotides of the RNA genome. Influenza A viruses differ by comprising multiple ribonucleoproteins, the viral NP protein organizes the RNA into a helical structure. The size is also different; the tobacco mosaic virus has a 16.33 protein subunits per helical turn, while the influenza A virus has a 28 amino acid tail loop.
The functions of the capsid are to:
The virus must assemble a stable, protective protein shell to protect the genome from lethal chemical and physical agents. These include extremes of pH or temperature and proteolytic and nucleolytic enzymes. For non-enveloped viruses, the capsid itself may be involved in interaction with receptors on the host cell, leading to penetration of the host cell membrane and internalization of the capsid. Delivery of the genome occurs by subsequent uncoating or disassembly of the capsid and release of the genome into the cytoplasm, or by ejection of the genome through a specialized portal structure directly into the host cell nucleus.
It has been suggested that many viral capsid proteins have evolved on multiple occasions from functionally diverse cellular proteins. The recruitment of cellular proteins appears to have occurred at different stages of evolution so that some cellular proteins were captured and refunctionalized prior to the divergence of cellular organisms into the three contemporary domains of life, whereas others were hijacked relatively recently. As a result, some capsid proteins are widespread in viruses infecting distantly related organisms (e.g., capsid proteins with the jelly-roll fold), whereas others are restricted to a particular group of viruses (e.g., capsid proteins of alphaviruses).
A computational model (2015) has shown that capsids may have originated before viruses and that they served as a means of horizontal transfer between replicator communities since these communities could not survive if the number of gene parasites increased, with certain genes being responsible for the formation of these structures and those that favored the survival of self-replicating communities. The displacement of these ancestral genes between cellular organisms could favor the appearance of new viruses during evolution. | [
{
"paragraph_id": 0,
"text": "A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The proteins making up the capsid are called capsid proteins or viral coat proteins (VCP). The capsid and inner genome is called the nucleocapsid.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Capsids are broadly classified according to their structure. The majority of the viruses have capsids with either helical or icosahedral structure. Some viruses, such as bacteriophages, have developed more complicated structures due to constraints of elasticity and electrostatics. The icosahedral shape, which has 20 equilateral triangular faces, approximates a sphere, while the helical shape resembles the shape of a spring, taking the space of a cylinder but not being a cylinder itself. The capsid faces may consist of one or more proteins. For example, the foot-and-mouth disease virus capsid has faces consisting of three proteins named VP1–3.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Some viruses are enveloped, meaning that the capsid is coated with a lipid membrane known as the viral envelope. The envelope is acquired by the capsid from an intracellular membrane in the virus' host; examples include the inner nuclear membrane, the Golgi membrane, and the cell's outer membrane.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Once the virus has infected a cell and begins replicating itself, new capsid subunits are synthesized using the protein biosynthesis mechanism of the cell. In some viruses, including those with helical capsids and especially those with RNA genomes, the capsid proteins co-assemble with their genomes. In other viruses, especially more complex viruses with double-stranded DNA genomes, the capsid proteins assemble into empty precursor procapsids that include a specialized portal structure at one vertex. Through this portal, viral DNA is translocated into the capsid.",
"title": ""
},
{
"paragraph_id": 4,
"text": "Structural analyses of major capsid protein (MCP) architectures have been used to categorise viruses into lineages. For example, the bacteriophage PRD1, the algal virus Paramecium bursaria Chlorella virus-1 (PBCV-1), mimivirus and the mammalian adenovirus have been placed in the same lineage, whereas tailed, double-stranded DNA bacteriophages (Caudovirales) and herpesvirus belong to a second lineage.",
"title": ""
},
{
"paragraph_id": 5,
"text": "The icosahedral structure is extremely common among viruses. The icosahedron consists of 20 triangular faces delimited by 12 fivefold vertexes and consists of 60 asymmetric units. Thus, an icosahedral virus is made of 60N protein subunits. The number and arrangement of capsomeres in an icosahedral capsid can be classified using the \"quasi-equivalence principle\" proposed by Donald Caspar and Aaron Klug. Like the Goldberg polyhedra, an icosahedral structure can be regarded as being constructed from pentamers and hexamers. The structures can be indexed by two integers h and k, with h ≥ 1 {\\displaystyle h\\geq 1} and k ≥ 0 {\\displaystyle k\\geq 0} ; the structure can be thought of as taking h steps from the edge of a pentamer, turning 60 degrees counterclockwise, then taking k steps to get to the next pentamer. The triangulation number T for the capsid is defined as:",
"title": "Specific shapes"
},
{
"paragraph_id": 6,
"text": "In this scheme, icosahedral capsids contain 12 pentamers plus 10(T − 1) hexamers. The T-number is representative of the size and complexity of the capsids. Geometric examples for many values of h, k, and T can be found at List of geodesic polyhedra and Goldberg polyhedra.",
"title": "Specific shapes"
},
{
"paragraph_id": 7,
"text": "Many exceptions to this rule exist: For example, the polyomaviruses and papillomaviruses have pentamers instead of hexamers in hexavalent positions on a quasi T = 7 lattice. Members of the double-stranded RNA virus lineage, including reovirus, rotavirus and bacteriophage φ6 have capsids built of 120 copies of capsid protein, corresponding to a T = 2 capsid, or arguably a T = 1 capsid with a dimer in the asymmetric unit. Similarly, many small viruses have a pseudo T = 3 (or P = 3) capsid, which is organized according to a T = 3 lattice, but with distinct polypeptides occupying the three quasi-equivalent positions",
"title": "Specific shapes"
},
{
"paragraph_id": 8,
"text": "T-numbers can be represented in different ways, for example T = 1 can only be represented as an icosahedron or a dodecahedron and, depending on the type of quasi-symmetry, T = 3 can be presented as a truncated dodecahedron, an icosidodecahedron, or a truncated icosahedron and their respective duals a triakis icosahedron, a rhombic triacontahedron, or a pentakis dodecahedron.",
"title": "Specific shapes"
},
{
"paragraph_id": 9,
"text": "An elongated icosahedron is a common shape for the heads of bacteriophages. Such a structure is composed of a cylinder with a cap at either end. The cylinder is composed of 10 elongated triangular faces. The Q number (or Tmid), which can be any positive integer, specifies the number of triangles, composed of asymmetric subunits, that make up the 10 triangles of the cylinder. The caps are classified by the T (or Tend) number.",
"title": "Specific shapes"
},
{
"paragraph_id": 10,
"text": "The bacterium E. coli is the host for bacteriophage T4 that has a prolate head structure. The bacteriophage encoded gp31 protein appears to be functionally homologous to E. coli chaperone protein GroES and able to substitute for it in the assembly of bacteriophage T4 virions during infection. Like GroES, gp31 forms a stable complex with GroEL chaperonin that is absolutely necessary for the folding and assembly in vivo of the bacteriophage T4 major capsid protein gp23.",
"title": "Specific shapes"
},
{
"paragraph_id": 11,
"text": "Many rod-shaped and filamentous plant viruses have capsids with helical symmetry. The helical structure can be described as a set of n 1-D molecular helices related by an n-fold axial symmetry. The helical transformation are classified into two categories: one-dimensional and two-dimensional helical systems. Creating an entire helical structure relies on a set of translational and rotational matrices which are coded in the protein data bank. Helical symmetry is given by the formula P = μ x ρ, where μ is the number of structural units per turn of the helix, ρ is the axial rise per unit and P is the pitch of the helix. The structure is said to be open due to the characteristic that any volume can be enclosed by varying the length of the helix. The most understood helical virus is the tobacco mosaic virus. The virus is a single molecule of (+) strand RNA. Each coat protein on the interior of the helix bind three nucleotides of the RNA genome. Influenza A viruses differ by comprising multiple ribonucleoproteins, the viral NP protein organizes the RNA into a helical structure. The size is also different; the tobacco mosaic virus has a 16.33 protein subunits per helical turn, while the influenza A virus has a 28 amino acid tail loop.",
"title": "Specific shapes"
},
{
"paragraph_id": 12,
"text": "The functions of the capsid are to:",
"title": "Functions"
},
{
"paragraph_id": 13,
"text": "The virus must assemble a stable, protective protein shell to protect the genome from lethal chemical and physical agents. These include extremes of pH or temperature and proteolytic and nucleolytic enzymes. For non-enveloped viruses, the capsid itself may be involved in interaction with receptors on the host cell, leading to penetration of the host cell membrane and internalization of the capsid. Delivery of the genome occurs by subsequent uncoating or disassembly of the capsid and release of the genome into the cytoplasm, or by ejection of the genome through a specialized portal structure directly into the host cell nucleus.",
"title": "Functions"
},
{
"paragraph_id": 14,
"text": "It has been suggested that many viral capsid proteins have evolved on multiple occasions from functionally diverse cellular proteins. The recruitment of cellular proteins appears to have occurred at different stages of evolution so that some cellular proteins were captured and refunctionalized prior to the divergence of cellular organisms into the three contemporary domains of life, whereas others were hijacked relatively recently. As a result, some capsid proteins are widespread in viruses infecting distantly related organisms (e.g., capsid proteins with the jelly-roll fold), whereas others are restricted to a particular group of viruses (e.g., capsid proteins of alphaviruses).",
"title": "Origin and evolution"
},
{
"paragraph_id": 15,
"text": "A computational model (2015) has shown that capsids may have originated before viruses and that they served as a means of horizontal transfer between replicator communities since these communities could not survive if the number of gene parasites increased, with certain genes being responsible for the formation of these structures and those that favored the survival of self-replicating communities. The displacement of these ancestral genes between cellular organisms could favor the appearance of new viruses during evolution.",
"title": "Origin and evolution"
}
] | A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The proteins making up the capsid are called capsid proteins or viral coat proteins (VCP). The capsid and inner genome is called the nucleocapsid. Capsids are broadly classified according to their structure. The majority of the viruses have capsids with either helical or icosahedral structure. Some viruses, such as bacteriophages, have developed more complicated structures due to constraints of elasticity and electrostatics. The icosahedral shape, which has 20 equilateral triangular faces, approximates a sphere, while the helical shape resembles the shape of a spring, taking the space of a cylinder but not being a cylinder itself. The capsid faces may consist of one or more proteins. For example, the foot-and-mouth disease virus capsid has faces consisting of three proteins named VP1–3. Some viruses are enveloped, meaning that the capsid is coated with a lipid membrane known as the viral envelope. The envelope is acquired by the capsid from an intracellular membrane in the virus' host; examples include the inner nuclear membrane, the Golgi membrane, and the cell's outer membrane. Once the virus has infected a cell and begins replicating itself, new capsid subunits are synthesized using the protein biosynthesis mechanism of the cell. In some viruses, including those with helical capsids and especially those with RNA genomes, the capsid proteins co-assemble with their genomes. In other viruses, especially more complex viruses with double-stranded DNA genomes, the capsid proteins assemble into empty precursor procapsids that include a specialized portal structure at one vertex. Through this portal, viral DNA is translocated into the capsid. Structural analyses of major capsid protein (MCP) architectures have been used to categorise viruses into lineages. For example, the bacteriophage PRD1, the algal virus Paramecium bursaria Chlorella virus-1 (PBCV-1), mimivirus and the mammalian adenovirus have been placed in the same lineage, whereas tailed, double-stranded DNA bacteriophages (Caudovirales) and herpesvirus belong to a second lineage. | 2002-02-25T15:43:11Z | 2023-12-12T01:15:20Z | [
"Template:Virus topics",
"Template:Clarify",
"Template:Portal",
"Template:Reflist",
"Template:Cite book",
"Template:Cite web",
"Template:Refend",
"Template:Commons category",
"Template:Short description",
"Template:Clear",
"Template:Cite journal",
"Template:Refbegin",
"Template:Authority control"
] | https://en.wikipedia.org/wiki/Capsid |
6,346 | Chloramphenicol | Chloramphenicol is an antibiotic useful for the treatment of a number of bacterial infections. This includes use as an eye ointment to treat conjunctivitis. By mouth or by injection into a vein, it is used to treat meningitis, plague, cholera, and typhoid fever. Its use by mouth or by injection is only recommended when safer antibiotics cannot be used. Monitoring both blood levels of the medication and blood cell levels every two days is recommended during treatment.
Common side effects include bone marrow suppression, nausea, and diarrhea. The bone marrow suppression may result in death. To reduce the risk of side effects treatment duration should be as short as possible. People with liver or kidney problems may need lower doses. In young children a condition known as gray baby syndrome may occur which results in a swollen stomach and low blood pressure. Its use near the end of pregnancy and during breastfeeding is typically not recommended. Chloramphenicol is a broad-spectrum antibiotic that typically stops bacterial growth by stopping the production of proteins.
Chloramphenicol was discovered after being isolated from Streptomyces venezuelae in 1947. Its chemical structure was identified and it was first synthesized in 1949. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication.
The original indication of chloramphenicol was in the treatment of typhoid, but the presence of multiple drug-resistant Salmonella typhi has meant it is seldom used for this indication except when the organism is known to be sensitive.
In low-income countries, the WHO no longer recommends only chloramphenicol as first-line to treat meningitis, but recognises it may be used with caution if there are no available alternatives.
During the last decade chloramphenicol has been re-evaluated as an old agent with potential against systemic infections due to multidrug-resistant gram positive microorganisms (including vancomycin resistant enterococci). In vitro data have shown an activity against the majority (> 80%) of vancomycin resistant E. faecium strains.
In the context of preventing endophthalmitis, a complication of cataract surgery, a 2017 systematic review found moderate evidence that using chloramphenicol eye drops in addition to an antibiotic injection (cefuroxime or penicillin) will likely lower the risk of endophthalmitis, compared to eye drops or antibiotic injections alone.
Chloramphenicol has a broad spectrum of activity and has been effective in treating ocular infections such as conjunctivitis, blepharitis etc. caused by a number of bacteria including Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli. It is not effective against Pseudomonas aeruginosa. The following susceptibility data represent the minimum inhibitory concentration for a few medically significant organisms.
Each of these concentrations is dependent upon the bacterial strain being targeted. Some strains of E. coli, for example, show spontaneous emergence of chloramphenicol resistance.
Three mechanisms of resistance to chloramphenicol are known: reduced membrane permeability, mutation of the 50S ribosomal subunit, and elaboration of chloramphenicol acetyltransferase. It is easy to select for reduced membrane permeability to chloramphenicol in vitro by serial passage of bacteria, and this is the most common mechanism of low-level chloramphenicol resistance. High-level resistance is conferred by the cat-gene; this gene codes for an enzyme called chloramphenicol acetyltransferase, which inactivates chloramphenicol by covalently linking one or two acetyl groups, derived from acetyl-S-coenzyme A, to the hydroxyl groups on the chloramphenicol molecule. The acetylation prevents chloramphenicol from binding to the ribosome. Resistance-conferring mutations of the 50S ribosomal subunit are rare.
Chloramphenicol resistance may be carried on a plasmid that also codes for resistance to other drugs. One example is the ACCoT plasmid (A=ampicillin, C=chloramphenicol, Co=co-trimoxazole, T=tetracycline), which mediates multiple drug resistance in typhoid (also called R factors).
As of 2014 some Enterococcus faecium and Pseudomonas aeruginosa strains are resistant to chloramphenicol. Some Veillonella spp. and Staphylococcus capitis strains have also developed resistance to chloramphenicol to varying degrees.
The most serious side effect of chloramphenicol treatment is aplastic anaemia ('AA'). This effect is rare but sometimes fatal. The risk of AA is high enough that alternatives should be strongly considered. Treatments are available but expensive. No way exists to predict who may or may not suffer this side effect. The effect usually occurs weeks or months after treatment has been stopped, and a genetic predisposition may be involved. It is not known whether monitoring the blood counts of patients can prevent the development of aplastic anaemia, but patients are recommended to have a baseline blood count with a repeat blood count every few days while on treatment. Chloramphenicol should be discontinued if the complete blood count drops. The highest risk is with oral chloramphenicol (affecting 1 in 24,000–40,000) and the lowest risk occurs with eye drops (affecting less than one in 224,716 prescriptions).
Thiamphenicol, a related compound with a similar spectrum of activity, is available in Italy and China for human use, and has never been associated with aplastic anaemia. Thiamphenicol is available in the U.S. and Europe as a veterinary antibiotic, but is not approved for use in humans.
Chloramphenicol may cause bone marrow suppression during treatment; this is a direct toxic effect of the drug on human mitochondria. This effect manifests first as a fall in hemoglobin levels, which occurs quite predictably once a cumulative dose of 20 g has been given. The anaemia is fully reversible once the drug is stopped and does not predict future development of aplastic anaemia. Studies in mice have suggested existing marrow damage may compound any marrow damage resulting from the toxic effects of chloramphenicol.
Leukemia, a cancer of the blood or bone marrow, is characterized by an abnormal increase of immature white blood cells. The risk of childhood leukemia is increased, as demonstrated in a Chinese case–control study, and the risk increases with length of treatment.
Intravenous chloramphenicol use has been associated with the so-called gray baby syndrome. This phenomenon occurs in newborn infants because they do not yet have fully functional liver enzymes (i.e. UDP-glucuronyl transferase), so chloramphenicol remains unmetabolized in the body. This causes several adverse effects, including hypotension and cyanosis. The condition can be prevented by using the drug at the recommended doses, and monitoring blood levels.
Fever, macular and vesicular rashes, angioedema, urticaria, and anaphylaxis may occur. Herxheimer's reactions have occurred during therapy for typhoid fever.
Headache, mild depression, mental confusion, and delirium have been described in patients receiving chloramphenicol. Optic and peripheral neuritis have been reported, usually following long-term therapy. If this occurs, the drug should be promptly withdrawn.
Chloramphenicol is extremely lipid-soluble; it remains relatively unbound to protein and is a small molecule. It has a large apparent volume of distribution and penetrates effectively into all tissues of the body, including the brain. Distribution is not uniform, with highest concentrations found in the liver and kidney, with lowest in the brain and cerebrospinal fluid. The concentration achieved in brain and cerebrospinal fluid is around 30 to 50% of the overall average body concentration, even when the meninges are not inflamed; this increases to as high as 89% when the meninges are inflamed.
Chloramphenicol increases the absorption of iron.
Chloramphenicol is metabolized by the liver to chloramphenicol glucuronate (which is inactive). In liver impairment, the dose of chloramphenicol must therefore be reduced. No standard dose reduction exists for chloramphenicol in liver impairment, and the dose should be adjusted according to measured plasma concentrations.
The majority of the chloramphenicol dose is excreted by the kidneys as the inactive metabolite, chloramphenicol glucuronate. Only a tiny fraction of the chloramphenicol is excreted by the kidneys unchanged. Plasma levels should be monitored in patients with renal impairment, but this is not mandatory. Chloramphenicol succinate ester (an intravenous prodrug form) is readily excreted unchanged by the kidneys, more so than chloramphenicol base, and this is the major reason why levels of chloramphenicol in the blood are much lower when given intravenously than orally. Chloramphenicol passes into breast milk, so should therefore be avoided during breast feeding, if possible.
Plasma levels of chloramphenicol must be monitored in neonates and patients with abnormal liver function. Plasma levels should be monitored in all children under the age of four, the elderly, and patients with kidney failure. Because efficacy and toxicity of chloramphenicol are associated with a maximum serum concentration, peak levels (one hour after the intravenous dose is given) should be 10–20 µg/ml with toxicity > 40 µg/ml; trough levels (taken immediately before a dose) should be 5–10 µg/ml.
Administration of chloramphenicol concomitantly with bone marrow depressant drugs is contraindicated, although concerns over aplastic anaemia associated with ocular chloramphenicol have largely been discounted.
Chloramphenicol is a potent inhibitor of the cytochrome P450 isoforms CYP2C19 and CYP3A4 in the liver. Inhibition of CYP2C19 causes decreased metabolism and therefore increased levels of, for example, antidepressants, antiepileptics, proton-pump inhibitors, and anticoagulants if they are given concomitantly. Inhibition of CYP3A4 causes increased levels of, for example, calcium channel blockers, immunosuppressants, chemotherapeutic drugs, benzodiazepines, azole antifungals, tricyclic antidepressants, macrolide antibiotics, SSRIs, statins, cardiac antiarrhythmics, antivirals, anticoagulants, and PDE5 inhibitors.
Chloramphenicol is antagonistic with most cephalosporins and using both together should be avoided in the treatment of infections.
Chloramphenicol has been demonstrated a synergistic effect when combined with fosfomycin against clinical isolates of Enterococcus faecium.
Chloramphenicol is a bacteriostatic agent, inhibiting protein synthesis. It prevents protein chain elongation by inhibiting the peptidyl transferase activity of the bacterial ribosome. It specifically binds to A2451 and A2452 residues in the 23S rRNA of the 50S ribosomal subunit, preventing peptide bond formation. Chloramphenicol directly interferes with substrate binding in the ribosome, as compared to macrolides, which sterically block the progression of the growing peptide.
Chloramphenicol was first isolated from Streptomyces venezuelae in 1947 and in 1949 a team of scientists at Parke-Davis including Mildred Rebstock published their identification of the chemical structure and their synthesis.
In 1972, Senator Ted Kennedy combined the two examples of the Tuskegee Syphilis Study and the 1958 Los Angeles Infant Chloramphenicol experiments as initial subjects of a Senate Subcommittee investigation into dangerous medical experimentation on human subjects.
In 2007, the accumulation of reports associating aplastic anemia and blood dyscrasia with chloramphenicol eye drops led to the classification of “probable human carcinogen” according to World Health Organization criteria, based on the known published case reports and the spontaneous reports submitted to the National Registry of Drug-Induced Ocular Side Effects.
Chloramphenicol is available as a generic worldwide under many brandnames and also under various generic names in eastern Europe and Russia, including chlornitromycin, levomycetin, and chloromycetin; the racemate is known as synthomycetin.
Chloramphenicol is available as a capsule or as a liquid. In some countries, it is sold as chloramphenicol palmitate ester (CPE). CPE is inactive, and is hydrolysed to active chloramphenicol in the small intestine. No difference in bioavailability is noted between chloramphenicol and CPE.
Manufacture of oral chloramphenicol in the U.S. stopped in 1991, because the vast majority of chloramphenicol-associated cases of aplastic anaemia are associated with the oral preparation. No oral formulation of chloramphenicol is available in the U.S. for human use.
In molecular biology, chloramphenicol is prepared in ethanol.
The intravenous (IV) preparation of chloramphenicol is the succinate ester. This creates a problem: Chloramphenicol succinate ester is an inactive prodrug and must first be hydrolysed to chloramphenicol; however, the hydrolysis process is often incomplete, and 30% of the dose is lost and removed in the urine. Serum concentrations of IV chloramphenicol are only 70% of those achieved when chloramphenicol is given orally. For this reason, the dose needs to be increased to 75 mg/kg/day when administered IV to achieve levels equivalent to the oral dose.
Oily chloramphenicol (or chloramphenicol oil suspension) is a long-acting preparation of chloramphenicol first introduced by Roussel in 1954; marketed as Tifomycine, it was originally used as a treatment for typhoid. Roussel stopped production of oily chloramphenicol in 1995; the International Dispensary Association Foundation has manufactured it since 1998, first in Malta and then in India from December 2004.
Oily chloramphenicol was first used to treat meningitis in 1975 and numerous studies since have demonstrated its efficacy. It is the cheapest treatment available for meningitis (US$5 per treatment course, compared to US$30 for ampicillin and US$15 for five days of ceftriaxone). It has the great advantage of requiring only a single injection, whereas ceftriaxone is traditionally given daily for five days. This recommendation may yet change, now that a single dose of ceftriaxone (cost US$3) has been shown to be equivalent to one dose of oily chloramphenicol.
Chloramphenicol is used in topical preparations (ointments and eye drops) for the treatment of bacterial conjunctivitis. Isolated case reports of aplastic anaemia following use of chloramphenicol eyedrops exist, but the risk is estimated to be of the order of less than one in 224,716 prescriptions. In Mexico, this is the treatment used prophylactically in newborns for neonatal conjunctivitis.
Although its use in veterinary medicine is highly restricted, chloramphenicol still has some important veterinary uses. It is currently considered the most useful treatment of chlamydial disease in koalas. The pharmacokinetics of chloramphenicol have been investigated in koalas. | [
{
"paragraph_id": 0,
"text": "Chloramphenicol is an antibiotic useful for the treatment of a number of bacterial infections. This includes use as an eye ointment to treat conjunctivitis. By mouth or by injection into a vein, it is used to treat meningitis, plague, cholera, and typhoid fever. Its use by mouth or by injection is only recommended when safer antibiotics cannot be used. Monitoring both blood levels of the medication and blood cell levels every two days is recommended during treatment.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Common side effects include bone marrow suppression, nausea, and diarrhea. The bone marrow suppression may result in death. To reduce the risk of side effects treatment duration should be as short as possible. People with liver or kidney problems may need lower doses. In young children a condition known as gray baby syndrome may occur which results in a swollen stomach and low blood pressure. Its use near the end of pregnancy and during breastfeeding is typically not recommended. Chloramphenicol is a broad-spectrum antibiotic that typically stops bacterial growth by stopping the production of proteins.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Chloramphenicol was discovered after being isolated from Streptomyces venezuelae in 1947. Its chemical structure was identified and it was first synthesized in 1949. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The original indication of chloramphenicol was in the treatment of typhoid, but the presence of multiple drug-resistant Salmonella typhi has meant it is seldom used for this indication except when the organism is known to be sensitive.",
"title": "Medical uses"
},
{
"paragraph_id": 4,
"text": "In low-income countries, the WHO no longer recommends only chloramphenicol as first-line to treat meningitis, but recognises it may be used with caution if there are no available alternatives.",
"title": "Medical uses"
},
{
"paragraph_id": 5,
"text": "During the last decade chloramphenicol has been re-evaluated as an old agent with potential against systemic infections due to multidrug-resistant gram positive microorganisms (including vancomycin resistant enterococci). In vitro data have shown an activity against the majority (> 80%) of vancomycin resistant E. faecium strains.",
"title": "Medical uses"
},
{
"paragraph_id": 6,
"text": "In the context of preventing endophthalmitis, a complication of cataract surgery, a 2017 systematic review found moderate evidence that using chloramphenicol eye drops in addition to an antibiotic injection (cefuroxime or penicillin) will likely lower the risk of endophthalmitis, compared to eye drops or antibiotic injections alone.",
"title": "Medical uses"
},
{
"paragraph_id": 7,
"text": "Chloramphenicol has a broad spectrum of activity and has been effective in treating ocular infections such as conjunctivitis, blepharitis etc. caused by a number of bacteria including Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli. It is not effective against Pseudomonas aeruginosa. The following susceptibility data represent the minimum inhibitory concentration for a few medically significant organisms.",
"title": "Medical uses"
},
{
"paragraph_id": 8,
"text": "Each of these concentrations is dependent upon the bacterial strain being targeted. Some strains of E. coli, for example, show spontaneous emergence of chloramphenicol resistance.",
"title": "Medical uses"
},
{
"paragraph_id": 9,
"text": "Three mechanisms of resistance to chloramphenicol are known: reduced membrane permeability, mutation of the 50S ribosomal subunit, and elaboration of chloramphenicol acetyltransferase. It is easy to select for reduced membrane permeability to chloramphenicol in vitro by serial passage of bacteria, and this is the most common mechanism of low-level chloramphenicol resistance. High-level resistance is conferred by the cat-gene; this gene codes for an enzyme called chloramphenicol acetyltransferase, which inactivates chloramphenicol by covalently linking one or two acetyl groups, derived from acetyl-S-coenzyme A, to the hydroxyl groups on the chloramphenicol molecule. The acetylation prevents chloramphenicol from binding to the ribosome. Resistance-conferring mutations of the 50S ribosomal subunit are rare.",
"title": "Medical uses"
},
{
"paragraph_id": 10,
"text": "Chloramphenicol resistance may be carried on a plasmid that also codes for resistance to other drugs. One example is the ACCoT plasmid (A=ampicillin, C=chloramphenicol, Co=co-trimoxazole, T=tetracycline), which mediates multiple drug resistance in typhoid (also called R factors).",
"title": "Medical uses"
},
{
"paragraph_id": 11,
"text": "As of 2014 some Enterococcus faecium and Pseudomonas aeruginosa strains are resistant to chloramphenicol. Some Veillonella spp. and Staphylococcus capitis strains have also developed resistance to chloramphenicol to varying degrees.",
"title": "Medical uses"
},
{
"paragraph_id": 12,
"text": "The most serious side effect of chloramphenicol treatment is aplastic anaemia ('AA'). This effect is rare but sometimes fatal. The risk of AA is high enough that alternatives should be strongly considered. Treatments are available but expensive. No way exists to predict who may or may not suffer this side effect. The effect usually occurs weeks or months after treatment has been stopped, and a genetic predisposition may be involved. It is not known whether monitoring the blood counts of patients can prevent the development of aplastic anaemia, but patients are recommended to have a baseline blood count with a repeat blood count every few days while on treatment. Chloramphenicol should be discontinued if the complete blood count drops. The highest risk is with oral chloramphenicol (affecting 1 in 24,000–40,000) and the lowest risk occurs with eye drops (affecting less than one in 224,716 prescriptions).",
"title": "Adverse effects"
},
{
"paragraph_id": 13,
"text": "Thiamphenicol, a related compound with a similar spectrum of activity, is available in Italy and China for human use, and has never been associated with aplastic anaemia. Thiamphenicol is available in the U.S. and Europe as a veterinary antibiotic, but is not approved for use in humans.",
"title": "Adverse effects"
},
{
"paragraph_id": 14,
"text": "Chloramphenicol may cause bone marrow suppression during treatment; this is a direct toxic effect of the drug on human mitochondria. This effect manifests first as a fall in hemoglobin levels, which occurs quite predictably once a cumulative dose of 20 g has been given. The anaemia is fully reversible once the drug is stopped and does not predict future development of aplastic anaemia. Studies in mice have suggested existing marrow damage may compound any marrow damage resulting from the toxic effects of chloramphenicol.",
"title": "Adverse effects"
},
{
"paragraph_id": 15,
"text": "Leukemia, a cancer of the blood or bone marrow, is characterized by an abnormal increase of immature white blood cells. The risk of childhood leukemia is increased, as demonstrated in a Chinese case–control study, and the risk increases with length of treatment.",
"title": "Adverse effects"
},
{
"paragraph_id": 16,
"text": "Intravenous chloramphenicol use has been associated with the so-called gray baby syndrome. This phenomenon occurs in newborn infants because they do not yet have fully functional liver enzymes (i.e. UDP-glucuronyl transferase), so chloramphenicol remains unmetabolized in the body. This causes several adverse effects, including hypotension and cyanosis. The condition can be prevented by using the drug at the recommended doses, and monitoring blood levels.",
"title": "Adverse effects"
},
{
"paragraph_id": 17,
"text": "Fever, macular and vesicular rashes, angioedema, urticaria, and anaphylaxis may occur. Herxheimer's reactions have occurred during therapy for typhoid fever.",
"title": "Adverse effects"
},
{
"paragraph_id": 18,
"text": "Headache, mild depression, mental confusion, and delirium have been described in patients receiving chloramphenicol. Optic and peripheral neuritis have been reported, usually following long-term therapy. If this occurs, the drug should be promptly withdrawn.",
"title": "Adverse effects"
},
{
"paragraph_id": 19,
"text": "Chloramphenicol is extremely lipid-soluble; it remains relatively unbound to protein and is a small molecule. It has a large apparent volume of distribution and penetrates effectively into all tissues of the body, including the brain. Distribution is not uniform, with highest concentrations found in the liver and kidney, with lowest in the brain and cerebrospinal fluid. The concentration achieved in brain and cerebrospinal fluid is around 30 to 50% of the overall average body concentration, even when the meninges are not inflamed; this increases to as high as 89% when the meninges are inflamed.",
"title": "Pharmacokinetics"
},
{
"paragraph_id": 20,
"text": "Chloramphenicol increases the absorption of iron.",
"title": "Pharmacokinetics"
},
{
"paragraph_id": 21,
"text": "Chloramphenicol is metabolized by the liver to chloramphenicol glucuronate (which is inactive). In liver impairment, the dose of chloramphenicol must therefore be reduced. No standard dose reduction exists for chloramphenicol in liver impairment, and the dose should be adjusted according to measured plasma concentrations.",
"title": "Pharmacokinetics"
},
{
"paragraph_id": 22,
"text": "The majority of the chloramphenicol dose is excreted by the kidneys as the inactive metabolite, chloramphenicol glucuronate. Only a tiny fraction of the chloramphenicol is excreted by the kidneys unchanged. Plasma levels should be monitored in patients with renal impairment, but this is not mandatory. Chloramphenicol succinate ester (an intravenous prodrug form) is readily excreted unchanged by the kidneys, more so than chloramphenicol base, and this is the major reason why levels of chloramphenicol in the blood are much lower when given intravenously than orally. Chloramphenicol passes into breast milk, so should therefore be avoided during breast feeding, if possible.",
"title": "Pharmacokinetics"
},
{
"paragraph_id": 23,
"text": "Plasma levels of chloramphenicol must be monitored in neonates and patients with abnormal liver function. Plasma levels should be monitored in all children under the age of four, the elderly, and patients with kidney failure. Because efficacy and toxicity of chloramphenicol are associated with a maximum serum concentration, peak levels (one hour after the intravenous dose is given) should be 10–20 µg/ml with toxicity > 40 µg/ml; trough levels (taken immediately before a dose) should be 5–10 µg/ml.",
"title": "Pharmacokinetics"
},
{
"paragraph_id": 24,
"text": "Administration of chloramphenicol concomitantly with bone marrow depressant drugs is contraindicated, although concerns over aplastic anaemia associated with ocular chloramphenicol have largely been discounted.",
"title": "Pharmacokinetics"
},
{
"paragraph_id": 25,
"text": "Chloramphenicol is a potent inhibitor of the cytochrome P450 isoforms CYP2C19 and CYP3A4 in the liver. Inhibition of CYP2C19 causes decreased metabolism and therefore increased levels of, for example, antidepressants, antiepileptics, proton-pump inhibitors, and anticoagulants if they are given concomitantly. Inhibition of CYP3A4 causes increased levels of, for example, calcium channel blockers, immunosuppressants, chemotherapeutic drugs, benzodiazepines, azole antifungals, tricyclic antidepressants, macrolide antibiotics, SSRIs, statins, cardiac antiarrhythmics, antivirals, anticoagulants, and PDE5 inhibitors.",
"title": "Pharmacokinetics"
},
{
"paragraph_id": 26,
"text": "Chloramphenicol is antagonistic with most cephalosporins and using both together should be avoided in the treatment of infections.",
"title": "Pharmacokinetics"
},
{
"paragraph_id": 27,
"text": "Chloramphenicol has been demonstrated a synergistic effect when combined with fosfomycin against clinical isolates of Enterococcus faecium.",
"title": "Pharmacokinetics"
},
{
"paragraph_id": 28,
"text": "Chloramphenicol is a bacteriostatic agent, inhibiting protein synthesis. It prevents protein chain elongation by inhibiting the peptidyl transferase activity of the bacterial ribosome. It specifically binds to A2451 and A2452 residues in the 23S rRNA of the 50S ribosomal subunit, preventing peptide bond formation. Chloramphenicol directly interferes with substrate binding in the ribosome, as compared to macrolides, which sterically block the progression of the growing peptide.",
"title": "Mechanism of action"
},
{
"paragraph_id": 29,
"text": "Chloramphenicol was first isolated from Streptomyces venezuelae in 1947 and in 1949 a team of scientists at Parke-Davis including Mildred Rebstock published their identification of the chemical structure and their synthesis.",
"title": "History"
},
{
"paragraph_id": 30,
"text": "In 1972, Senator Ted Kennedy combined the two examples of the Tuskegee Syphilis Study and the 1958 Los Angeles Infant Chloramphenicol experiments as initial subjects of a Senate Subcommittee investigation into dangerous medical experimentation on human subjects.",
"title": "History"
},
{
"paragraph_id": 31,
"text": "In 2007, the accumulation of reports associating aplastic anemia and blood dyscrasia with chloramphenicol eye drops led to the classification of “probable human carcinogen” according to World Health Organization criteria, based on the known published case reports and the spontaneous reports submitted to the National Registry of Drug-Induced Ocular Side Effects.",
"title": "History"
},
{
"paragraph_id": 32,
"text": "Chloramphenicol is available as a generic worldwide under many brandnames and also under various generic names in eastern Europe and Russia, including chlornitromycin, levomycetin, and chloromycetin; the racemate is known as synthomycetin.",
"title": "Society and culture"
},
{
"paragraph_id": 33,
"text": "Chloramphenicol is available as a capsule or as a liquid. In some countries, it is sold as chloramphenicol palmitate ester (CPE). CPE is inactive, and is hydrolysed to active chloramphenicol in the small intestine. No difference in bioavailability is noted between chloramphenicol and CPE.",
"title": "Society and culture"
},
{
"paragraph_id": 34,
"text": "Manufacture of oral chloramphenicol in the U.S. stopped in 1991, because the vast majority of chloramphenicol-associated cases of aplastic anaemia are associated with the oral preparation. No oral formulation of chloramphenicol is available in the U.S. for human use.",
"title": "Society and culture"
},
{
"paragraph_id": 35,
"text": "In molecular biology, chloramphenicol is prepared in ethanol.",
"title": "Society and culture"
},
{
"paragraph_id": 36,
"text": "The intravenous (IV) preparation of chloramphenicol is the succinate ester. This creates a problem: Chloramphenicol succinate ester is an inactive prodrug and must first be hydrolysed to chloramphenicol; however, the hydrolysis process is often incomplete, and 30% of the dose is lost and removed in the urine. Serum concentrations of IV chloramphenicol are only 70% of those achieved when chloramphenicol is given orally. For this reason, the dose needs to be increased to 75 mg/kg/day when administered IV to achieve levels equivalent to the oral dose.",
"title": "Society and culture"
},
{
"paragraph_id": 37,
"text": "Oily chloramphenicol (or chloramphenicol oil suspension) is a long-acting preparation of chloramphenicol first introduced by Roussel in 1954; marketed as Tifomycine, it was originally used as a treatment for typhoid. Roussel stopped production of oily chloramphenicol in 1995; the International Dispensary Association Foundation has manufactured it since 1998, first in Malta and then in India from December 2004.",
"title": "Society and culture"
},
{
"paragraph_id": 38,
"text": "Oily chloramphenicol was first used to treat meningitis in 1975 and numerous studies since have demonstrated its efficacy. It is the cheapest treatment available for meningitis (US$5 per treatment course, compared to US$30 for ampicillin and US$15 for five days of ceftriaxone). It has the great advantage of requiring only a single injection, whereas ceftriaxone is traditionally given daily for five days. This recommendation may yet change, now that a single dose of ceftriaxone (cost US$3) has been shown to be equivalent to one dose of oily chloramphenicol.",
"title": "Society and culture"
},
{
"paragraph_id": 39,
"text": "Chloramphenicol is used in topical preparations (ointments and eye drops) for the treatment of bacterial conjunctivitis. Isolated case reports of aplastic anaemia following use of chloramphenicol eyedrops exist, but the risk is estimated to be of the order of less than one in 224,716 prescriptions. In Mexico, this is the treatment used prophylactically in newborns for neonatal conjunctivitis.",
"title": "Society and culture"
},
{
"paragraph_id": 40,
"text": "Although its use in veterinary medicine is highly restricted, chloramphenicol still has some important veterinary uses. It is currently considered the most useful treatment of chlamydial disease in koalas. The pharmacokinetics of chloramphenicol have been investigated in koalas.",
"title": "Veterinary uses"
}
] | Chloramphenicol is an antibiotic useful for the treatment of a number of bacterial infections. This includes use as an eye ointment to treat conjunctivitis. By mouth or by injection into a vein, it is used to treat meningitis, plague, cholera, and typhoid fever. Its use by mouth or by injection is only recommended when safer antibiotics cannot be used. Monitoring both blood levels of the medication and blood cell levels every two days is recommended during treatment. Common side effects include bone marrow suppression, nausea, and diarrhea. The bone marrow suppression may result in death. To reduce the risk of side effects treatment duration should be as short as possible. People with liver or kidney problems may need lower doses. In young children a condition known as gray baby syndrome may occur which results in a swollen stomach and low blood pressure. Its use near the end of pregnancy and during breastfeeding is typically not recommended. Chloramphenicol is a broad-spectrum antibiotic that typically stops bacterial growth by stopping the production of proteins. Chloramphenicol was discovered after being isolated from Streptomyces venezuelae in 1947. Its chemical structure was identified and it was first synthesized in 1949. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. | 2002-02-16T12:17:50Z | 2023-11-27T19:03:01Z | [
"Template:Citation needed",
"Template:Rp",
"Template:Cite encyclopedia",
"Template:Cite news",
"Template:Antibiotics and chemotherapeutics for dermatological use",
"Template:Gynecological anti-infectives and antiseptics",
"Template:Short description",
"Template:Medical citation needed",
"Template:Cite journal",
"Template:Otologicals",
"Template:TOC limit",
"Template:Nowrap",
"Template:Amphenicols",
"Template:Portal bar",
"Template:Reflist",
"Template:Cite web",
"Template:Authority control",
"Template:Infobox drug",
"Template:Cite book"
] | https://en.wikipedia.org/wiki/Chloramphenicol |
6,347 | Cut-up technique | The cut-up technique (or découpé in French) is an aleatory literary technique in which a written text is cut up and rearranged to create a new text. The concept can be traced to the Dadaists of the 1920s, but it was developed and popularized in the 1950s and early 1960s, especially by writer William S. Burroughs. It has since been used in a wide variety of contexts.
The cut-up and the closely associated fold-in are the two main techniques:
William Burroughs cited T. S. Eliot's 1922 poem, The Waste Land, and John Dos Passos' U.S.A. trilogy, which incorporated newspaper clippings, as early examples of the cut ups he popularized.
Gysin introduced Burroughs to the technique at the Beat Hotel. The pair later applied the technique to printed media and audio recordings in an effort to decode the material's implicit content, hypothesizing that such a technique could be used to discover the true meaning of a given text. Burroughs also suggested cut-ups may be effective as a form of divination saying, "When you cut into the present the future leaks out." Burroughs also further developed the "fold-in" technique. In 1977, Burroughs and Gysin published The Third Mind, a collection of cut-up writings and essays on the form. Jeff Nuttall's publication My Own Mag was another important outlet for the then-radical technique.
In an interview, Alan Burns noted that for Europe After The Rain (1965) and subsequent novels he used a version of cut-ups: "I did not actually use scissors, but I folded pages, read across columns, and so on, discovering for myself many of the techniques Burroughs and Gysin describe".
A precedent of the technique occurred during a Dadaist rally in the 1920s in which Tristan Tzara offered to create a poem on the spot by pulling words at random from a hat. Collage, which was popularized roughly contemporaneously with the Surrealist movement, sometimes incorporated texts such as newspapers or brochures. Prior to this event, the technique had been published in an issue of 391 in the poem by Tzara, dada manifesto on feeble love and bitter love under the sub-title, TO MAKE A DADAIST POEM.
In the 1950s, painter and writer Brion Gysin more fully developed the cut-up method after accidentally rediscovering it. He had placed layers of newspapers as a mat to protect a tabletop from being scratched while he cut papers with a razor blade. Upon cutting through the newspapers, Gysin noticed that the sliced layers offered interesting juxtapositions of text and image. He began deliberately cutting newspaper articles into sections, which he randomly rearranged. The book Minutes to Go resulted from his initial cut-up experiment: unedited and unchanged cut-ups which emerged as coherent and meaningful prose. South African poet Sinclair Beiles also used this technique and co-authored Minutes To Go.
Argentine writer Julio Cortázar used cut ups in his 1963 novel Hopscotch.
In 1969, poets Howard W. Bergerson and J. A. Lindon developed a cut-up technique known as vocabularyclept poetry, in which a poem is formed by taking all the words of an existing poem and rearranging them, often preserving the metre and stanza lengths.
A drama scripted for five voices by performance poet Hedwig Gorski in 1977 originated the idea of creating poetry only for performance instead of for print publication. The "neo-verse drama" titled Booby, Mama! written for "guerilla theater" performances in public places used a combination of newspaper cut-ups that were edited and choreographed for a troupe of non-professional street actors.
Kathy Acker, a literary and intermedia artist, sampled external sources and reconfigured them into the creation of shifting versions of her own constructed identity. In her late 1970s novel Blood and Guts in High School, Acker explored literary cut-up and appropriation as an integral part of her method.
Antony Balch and Burroughs created a collaboration film, The Cut-Ups that opened in London in 1967. This was part of an abandoned project called Guerrilla Conditions meant as a documentary on Burroughs and filmed throughout 1961–1965. Inspired by Burroughs' and Gysin's technique of cutting up text and rearranging it in random order, Balch had an editor cut his footage for the documentary into little pieces and impose no control over its reassembly. The film opened at Oxford Street's Cinephone cinema and had a disturbing reaction. Many audience members claimed the film made them ill, others demanded their money back, while some just stumbled out of the cinema ranting "it's disgusting". Other cut-up films include Ghost at n°9 (Paris) (1963–1972), a posthumously released short film compiled from reels found at Balch's office after his death, and William Buys a Parrott (1982), Bill and Tony (1972), Towers Open Fire (1963) and The Junky's Christmas (1966).
In 1962, the satirical comedy group Bonzo Dog Doo-Dah Band, got their name after using the cut-up technique, resulting in "Bonzo Dog Dada": "Bonzo Dog", after the cartoon Bonzo the Dog, and "Dada" after the Dada avant-garde art movement. The group's eventual frontman, Vivian Stanshall, would quote about wanting to form a band with that name. The "Dada" in the phrase was eventually changed to "Doo-Dah".
From the early 1970s, David Bowie used cut-ups to create some of his lyrics. In 1995 he worked with Ty Roberts to develop a program called Verbasizer for his Apple PowerBook that could automatically rearrange multiple sentences written into it. Thom Yorke applied a similar method in Radiohead's Kid A (2000) album, writing single lines, putting them into a hat, and drawing them out at random while the band rehearsed the songs. Perhaps indicative of Thom Yorke's influences, instructions for "How to make a Dada poem" appeared on Radiohead's website at this time.
Stephen Mallinder of Cabaret Voltaire reported to Inpress magazine's Andrez Bergen that "I do think the manipulation of sound in our early days – the physical act of cutting up tapes, creating tape loops and all that – has a strong reference to Burroughs and Gysin." Another industrial music pioneer, Al Jourgensen of Ministry, named Burroughs and his cut-up technique as the most important influence on how he approached the use of samples.
Many Elephant 6 bands used decoupe as well, one prominent example of this is seen in "Pree-Sisters Swallowing A Donkey's Eye" by Neutral Milk Hotel. | [
{
"paragraph_id": 0,
"text": "The cut-up technique (or découpé in French) is an aleatory literary technique in which a written text is cut up and rearranged to create a new text. The concept can be traced to the Dadaists of the 1920s, but it was developed and popularized in the 1950s and early 1960s, especially by writer William S. Burroughs. It has since been used in a wide variety of contexts.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The cut-up and the closely associated fold-in are the two main techniques:",
"title": "Technique"
},
{
"paragraph_id": 2,
"text": "William Burroughs cited T. S. Eliot's 1922 poem, The Waste Land, and John Dos Passos' U.S.A. trilogy, which incorporated newspaper clippings, as early examples of the cut ups he popularized.",
"title": "Technique"
},
{
"paragraph_id": 3,
"text": "Gysin introduced Burroughs to the technique at the Beat Hotel. The pair later applied the technique to printed media and audio recordings in an effort to decode the material's implicit content, hypothesizing that such a technique could be used to discover the true meaning of a given text. Burroughs also suggested cut-ups may be effective as a form of divination saying, \"When you cut into the present the future leaks out.\" Burroughs also further developed the \"fold-in\" technique. In 1977, Burroughs and Gysin published The Third Mind, a collection of cut-up writings and essays on the form. Jeff Nuttall's publication My Own Mag was another important outlet for the then-radical technique.",
"title": "Technique"
},
{
"paragraph_id": 4,
"text": "In an interview, Alan Burns noted that for Europe After The Rain (1965) and subsequent novels he used a version of cut-ups: \"I did not actually use scissors, but I folded pages, read across columns, and so on, discovering for myself many of the techniques Burroughs and Gysin describe\".",
"title": "Technique"
},
{
"paragraph_id": 5,
"text": "A precedent of the technique occurred during a Dadaist rally in the 1920s in which Tristan Tzara offered to create a poem on the spot by pulling words at random from a hat. Collage, which was popularized roughly contemporaneously with the Surrealist movement, sometimes incorporated texts such as newspapers or brochures. Prior to this event, the technique had been published in an issue of 391 in the poem by Tzara, dada manifesto on feeble love and bitter love under the sub-title, TO MAKE A DADAIST POEM.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "In the 1950s, painter and writer Brion Gysin more fully developed the cut-up method after accidentally rediscovering it. He had placed layers of newspapers as a mat to protect a tabletop from being scratched while he cut papers with a razor blade. Upon cutting through the newspapers, Gysin noticed that the sliced layers offered interesting juxtapositions of text and image. He began deliberately cutting newspaper articles into sections, which he randomly rearranged. The book Minutes to Go resulted from his initial cut-up experiment: unedited and unchanged cut-ups which emerged as coherent and meaningful prose. South African poet Sinclair Beiles also used this technique and co-authored Minutes To Go.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "Argentine writer Julio Cortázar used cut ups in his 1963 novel Hopscotch.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "In 1969, poets Howard W. Bergerson and J. A. Lindon developed a cut-up technique known as vocabularyclept poetry, in which a poem is formed by taking all the words of an existing poem and rearranging them, often preserving the metre and stanza lengths.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "A drama scripted for five voices by performance poet Hedwig Gorski in 1977 originated the idea of creating poetry only for performance instead of for print publication. The \"neo-verse drama\" titled Booby, Mama! written for \"guerilla theater\" performances in public places used a combination of newspaper cut-ups that were edited and choreographed for a troupe of non-professional street actors.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "Kathy Acker, a literary and intermedia artist, sampled external sources and reconfigured them into the creation of shifting versions of her own constructed identity. In her late 1970s novel Blood and Guts in High School, Acker explored literary cut-up and appropriation as an integral part of her method.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "Antony Balch and Burroughs created a collaboration film, The Cut-Ups that opened in London in 1967. This was part of an abandoned project called Guerrilla Conditions meant as a documentary on Burroughs and filmed throughout 1961–1965. Inspired by Burroughs' and Gysin's technique of cutting up text and rearranging it in random order, Balch had an editor cut his footage for the documentary into little pieces and impose no control over its reassembly. The film opened at Oxford Street's Cinephone cinema and had a disturbing reaction. Many audience members claimed the film made them ill, others demanded their money back, while some just stumbled out of the cinema ranting \"it's disgusting\". Other cut-up films include Ghost at n°9 (Paris) (1963–1972), a posthumously released short film compiled from reels found at Balch's office after his death, and William Buys a Parrott (1982), Bill and Tony (1972), Towers Open Fire (1963) and The Junky's Christmas (1966).",
"title": "History"
},
{
"paragraph_id": 12,
"text": "In 1962, the satirical comedy group Bonzo Dog Doo-Dah Band, got their name after using the cut-up technique, resulting in \"Bonzo Dog Dada\": \"Bonzo Dog\", after the cartoon Bonzo the Dog, and \"Dada\" after the Dada avant-garde art movement. The group's eventual frontman, Vivian Stanshall, would quote about wanting to form a band with that name. The \"Dada\" in the phrase was eventually changed to \"Doo-Dah\".",
"title": "History"
},
{
"paragraph_id": 13,
"text": "From the early 1970s, David Bowie used cut-ups to create some of his lyrics. In 1995 he worked with Ty Roberts to develop a program called Verbasizer for his Apple PowerBook that could automatically rearrange multiple sentences written into it. Thom Yorke applied a similar method in Radiohead's Kid A (2000) album, writing single lines, putting them into a hat, and drawing them out at random while the band rehearsed the songs. Perhaps indicative of Thom Yorke's influences, instructions for \"How to make a Dada poem\" appeared on Radiohead's website at this time.",
"title": "History"
},
{
"paragraph_id": 14,
"text": "Stephen Mallinder of Cabaret Voltaire reported to Inpress magazine's Andrez Bergen that \"I do think the manipulation of sound in our early days – the physical act of cutting up tapes, creating tape loops and all that – has a strong reference to Burroughs and Gysin.\" Another industrial music pioneer, Al Jourgensen of Ministry, named Burroughs and his cut-up technique as the most important influence on how he approached the use of samples.",
"title": "History"
},
{
"paragraph_id": 15,
"text": "Many Elephant 6 bands used decoupe as well, one prominent example of this is seen in \"Pree-Sisters Swallowing A Donkey's Eye\" by Neutral Milk Hotel.",
"title": "History"
}
] | The cut-up technique is an aleatory literary technique in which a written text is cut up and rearranged to create a new text. The concept can be traced to the Dadaists of the 1920s, but it was developed and popularized in the 1950s and early 1960s, especially by writer William S. Burroughs. It has since been used in a wide variety of contexts. | 2001-10-02T03:01:43Z | 2023-12-18T08:10:13Z | [
"Template:Short description",
"Template:Cite journal",
"Template:Cite book",
"Template:Citation",
"Template:Literary composition",
"Template:William S. Burroughs",
"Template:Use dmy dates",
"Template:Cn",
"Template:Cite web",
"Template:ISBN",
"Template:Appropriation in the Arts",
"Template:Chaos magic series"
] | https://en.wikipedia.org/wiki/Cut-up_technique |
6,352 | Congenital iodine deficiency syndrome | Congenital iodine deficiency syndrome (CIDS) is a medical condition present at birth marked by impaired physical and mental development, due to insufficient thyroid hormone (hypothyroidism) often caused by insufficient dietary iodine during pregnancy. It is one cause of underactive thyroid function at birth, called congenital hypothyroidism, historically referred to as cretinism (obsolete). If untreated, it results in impairment of both physical and mental development. Symptoms may include goiter, poor length growth in infants, reduced adult stature, thickened skin, hair loss, enlarged tongue, a protruding abdomen; delayed bone maturation and puberty in children; and mental deterioration, neurological impairment, impeded ovulation, and infertility in adults.
In developed countries, thyroid function testing of newborns has assured that in those affected, treatment with the thyroid hormone thyroxine is begun promptly. This screening and treatment have virtually eliminated the consequences of the disease.
Iodine deficiency causes gradual enlargement of the thyroid gland, referred to as a goiter. Poor length growth is apparent as early as the first year of life. Adult stature without treatment ranges from 100 to 160 cm (3 ft 3 in to 5 ft 3 in), depending on severity, sex, and other genetic factors. Other signs include thickened skin, hair loss, enlarged tongue, and a protruding abdomen. In children, bone maturation and puberty are severely delayed. In adults, ovulation is impeded and infertility is common.
Mental deterioration is common. Neurological impairment may be mild, with reduced muscle tone and coordination, or so severe that the person cannot stand or walk. Cognitive impairment may also range from mild to so severe that the person is nonverbal and dependent on others for basic care. Thought and reflexes are slower.
Around the world, the most common cause of congenital iodine deficiency syndrome (endemic cretinism) is dietary iodine deficiency.
Iodine is an essential trace element, necessary for the synthesis of thyroid hormones. Iodine deficiency is the most common preventable cause of neonatal and childhood brain damage worldwide. Although iodine is found in many foods, it is not universally present in all soils in adequate amounts. Most iodine, in iodide form, is in the oceans, where the iodide ions are reduced to elemental iodine, which then enters the atmosphere and falls to earth in rain, introducing iodine to soils. Soil deficient in iodine is most common inland, in mountainous areas, and in areas of frequent flooding. It can also occur in coastal regions, where iodine might have been removed from the soil by glaciation, as well as leaching by snow, water and heavy rainfall. Plants and animals grown in iodine-deficient soils are correspondingly deficient. Populations living in those areas without outside food sources are most at risk of iodine deficiency diseases.
Dwarfism may also be caused by malnutrition or other hormonal deficiencies, such as insufficient growth hormone secretion, hypopituitarism, decreased secretion of growth hormone-releasing hormone, deficient growth hormone receptor activity and downstream causes, such as insulin-like growth factor 1 (IGF-1) deficiency.
There are public health campaigns in many countries which involve iodine administration. As of December 2019, 122 countries have mandatory iodine food fortification programs.
Congenital iodine deficiency has been almost eliminated in developed countries through iodine supplementation of food and by newborn screening utilizing a blood test for thyroid function.
Treatment consists of lifelong administration of thyroxine (T4). Thyroxine must be dosed as tablets only, even to newborns, as the liquid oral suspensions and compounded forms cannot be depended on for reliable dosing. For infants, the T4 tablets are generally crushed and mixed with breast milk, formula milk or water. If the medication is mixed with formulas containing iron or soya products, larger doses may be required, as these substances may alter the absorption of thyroid hormone from the gut. Monitoring TSH blood levels every 2–3 weeks during the first months of life is recommended to ensure that affected infants are at the high end of normal range.
A goiter is the most specific clinical marker of either the direct or indirect insufficient intake of iodine in the human body. There is evidence of goiter, and its medical treatment with iodine-rich algae and burnt sponges, in Chinese, Egyptian, and Roman ancient medical texts. In 1848, King Carlo Alberto of Sardinia commissioned the first epidemiological study of congenital iodine deficiency syndrome, in northern Savoy where it was frequent. In past centuries, the well reported social diseases prevalent among the poorer social classes and farmers, caused by dietary and agricultural monocultures, were: pellagra, rickets, beriberi, scurvy in long-term sailors, and the endemic goiter caused by iodine deficiency. However, this disease was less mentioned in medical books because it was erroneously considered to be an aesthetic rather than a clinical disorder.
Congenital iodine-deficiency syndrome was especially common in areas of southern Europe around the Alps and was often described by ancient Roman writers and depicted by artists. The earliest Alpine mountain climbers sometimes came upon whole villages affected by it. The prevalence of the condition was described from a medical perspective by several travellers and physicians in the late 18th and early 19th centuries. At that time the cause was not known and it was often attributed to "stagnant air" in mountain valleys or "bad water". The proportion of people affected varied markedly throughout southern Europe and even within very small areas; it might be common in one valley and not another. The number of severely affected persons was always a minority, and most persons were only affected to the extent of having a goitre and some degree of reduced cognition and growth. The majority of such cases were still socially functional in their pastoral villages.
More mildly affected areas of Europe and North America in the 19th century were referred to as "goitre belts". The degree of iodine deficiency was milder and manifested primarily as thyroid enlargement rather than severe mental and physical impairment. In Switzerland, for example, where soil does not contain a large amount of iodine, cases of congenital iodine deficiency syndrome were very abundant and even considered genetically caused. As the variety of food sources dramatically increased in Europe and North America and the populations became less completely dependent on locally grown food, the prevalence of endemic goitre diminished. This is supported by a 1979 WHO publication which concluded that "changes in the origin of food supplies may account for the otherwise unexplained disappearance of endemic goitre from a number of localities during the past 50 years".
The early 20th century saw the discovery of the relationships of neurological impairment with hypothyroidism due to iodine deficiency. Both have been largely eliminated in the developed world.
The term cretin was originally used to describe a person affected by this condition, but, as with words such as spastic and lunatic, it underwent pejoration and is now considered derogatory and inappropriate. Cretin became a medical term in the 18th century, from an Occitan and an Alpine French expression, prevalent in a region where persons with such a condition were especially common (see below); it saw wide medical use in the 19th and early 20th centuries, and was a "tick box" category on Victorian-era census forms in the UK. The term spread more widely in popular English as a markedly derogatory term for a person who behaves stupidly. Because of its pejorative connotations in popular speech, current usage among health care professionals has abandoned the noun "cretin" referring to a person. The noun cretinism, referring to the condition, still occurs in medical literature and textbooks but its use is waning.
The etymology of cretin is uncertain. Several hypotheses exist. The most common derivation provided in English dictionaries is from the Alpine French dialect pronunciation of the word Chrétien ("(a) Christian"), which was a greeting there. According to the Oxford English Dictionary, the translation of the French term into "human creature" implies that the label "Christian" is a reminder of the humanity of the affected, in contrast to brute beasts. Other sources suggest that Christian describes the person's "Christ-like" inability to sin, stemming, in such cases, from an incapacity to distinguish right from wrong.
Other speculative etymologies have been offered:
Media related to Congenital iodine deficiency syndrome at Wikimedia Commons | [
{
"paragraph_id": 0,
"text": "Congenital iodine deficiency syndrome (CIDS) is a medical condition present at birth marked by impaired physical and mental development, due to insufficient thyroid hormone (hypothyroidism) often caused by insufficient dietary iodine during pregnancy. It is one cause of underactive thyroid function at birth, called congenital hypothyroidism, historically referred to as cretinism (obsolete). If untreated, it results in impairment of both physical and mental development. Symptoms may include goiter, poor length growth in infants, reduced adult stature, thickened skin, hair loss, enlarged tongue, a protruding abdomen; delayed bone maturation and puberty in children; and mental deterioration, neurological impairment, impeded ovulation, and infertility in adults.",
"title": ""
},
{
"paragraph_id": 1,
"text": "In developed countries, thyroid function testing of newborns has assured that in those affected, treatment with the thyroid hormone thyroxine is begun promptly. This screening and treatment have virtually eliminated the consequences of the disease.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Iodine deficiency causes gradual enlargement of the thyroid gland, referred to as a goiter. Poor length growth is apparent as early as the first year of life. Adult stature without treatment ranges from 100 to 160 cm (3 ft 3 in to 5 ft 3 in), depending on severity, sex, and other genetic factors. Other signs include thickened skin, hair loss, enlarged tongue, and a protruding abdomen. In children, bone maturation and puberty are severely delayed. In adults, ovulation is impeded and infertility is common.",
"title": "Signs and symptoms"
},
{
"paragraph_id": 3,
"text": "Mental deterioration is common. Neurological impairment may be mild, with reduced muscle tone and coordination, or so severe that the person cannot stand or walk. Cognitive impairment may also range from mild to so severe that the person is nonverbal and dependent on others for basic care. Thought and reflexes are slower.",
"title": "Signs and symptoms"
},
{
"paragraph_id": 4,
"text": "Around the world, the most common cause of congenital iodine deficiency syndrome (endemic cretinism) is dietary iodine deficiency.",
"title": "Cause"
},
{
"paragraph_id": 5,
"text": "Iodine is an essential trace element, necessary for the synthesis of thyroid hormones. Iodine deficiency is the most common preventable cause of neonatal and childhood brain damage worldwide. Although iodine is found in many foods, it is not universally present in all soils in adequate amounts. Most iodine, in iodide form, is in the oceans, where the iodide ions are reduced to elemental iodine, which then enters the atmosphere and falls to earth in rain, introducing iodine to soils. Soil deficient in iodine is most common inland, in mountainous areas, and in areas of frequent flooding. It can also occur in coastal regions, where iodine might have been removed from the soil by glaciation, as well as leaching by snow, water and heavy rainfall. Plants and animals grown in iodine-deficient soils are correspondingly deficient. Populations living in those areas without outside food sources are most at risk of iodine deficiency diseases.",
"title": "Cause"
},
{
"paragraph_id": 6,
"text": "Dwarfism may also be caused by malnutrition or other hormonal deficiencies, such as insufficient growth hormone secretion, hypopituitarism, decreased secretion of growth hormone-releasing hormone, deficient growth hormone receptor activity and downstream causes, such as insulin-like growth factor 1 (IGF-1) deficiency.",
"title": "Diagnosis"
},
{
"paragraph_id": 7,
"text": "There are public health campaigns in many countries which involve iodine administration. As of December 2019, 122 countries have mandatory iodine food fortification programs.",
"title": "Prevention"
},
{
"paragraph_id": 8,
"text": "Congenital iodine deficiency has been almost eliminated in developed countries through iodine supplementation of food and by newborn screening utilizing a blood test for thyroid function.",
"title": "Treatment"
},
{
"paragraph_id": 9,
"text": "Treatment consists of lifelong administration of thyroxine (T4). Thyroxine must be dosed as tablets only, even to newborns, as the liquid oral suspensions and compounded forms cannot be depended on for reliable dosing. For infants, the T4 tablets are generally crushed and mixed with breast milk, formula milk or water. If the medication is mixed with formulas containing iron or soya products, larger doses may be required, as these substances may alter the absorption of thyroid hormone from the gut. Monitoring TSH blood levels every 2–3 weeks during the first months of life is recommended to ensure that affected infants are at the high end of normal range.",
"title": "Treatment"
},
{
"paragraph_id": 10,
"text": "A goiter is the most specific clinical marker of either the direct or indirect insufficient intake of iodine in the human body. There is evidence of goiter, and its medical treatment with iodine-rich algae and burnt sponges, in Chinese, Egyptian, and Roman ancient medical texts. In 1848, King Carlo Alberto of Sardinia commissioned the first epidemiological study of congenital iodine deficiency syndrome, in northern Savoy where it was frequent. In past centuries, the well reported social diseases prevalent among the poorer social classes and farmers, caused by dietary and agricultural monocultures, were: pellagra, rickets, beriberi, scurvy in long-term sailors, and the endemic goiter caused by iodine deficiency. However, this disease was less mentioned in medical books because it was erroneously considered to be an aesthetic rather than a clinical disorder.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "Congenital iodine-deficiency syndrome was especially common in areas of southern Europe around the Alps and was often described by ancient Roman writers and depicted by artists. The earliest Alpine mountain climbers sometimes came upon whole villages affected by it. The prevalence of the condition was described from a medical perspective by several travellers and physicians in the late 18th and early 19th centuries. At that time the cause was not known and it was often attributed to \"stagnant air\" in mountain valleys or \"bad water\". The proportion of people affected varied markedly throughout southern Europe and even within very small areas; it might be common in one valley and not another. The number of severely affected persons was always a minority, and most persons were only affected to the extent of having a goitre and some degree of reduced cognition and growth. The majority of such cases were still socially functional in their pastoral villages.",
"title": "History"
},
{
"paragraph_id": 12,
"text": "More mildly affected areas of Europe and North America in the 19th century were referred to as \"goitre belts\". The degree of iodine deficiency was milder and manifested primarily as thyroid enlargement rather than severe mental and physical impairment. In Switzerland, for example, where soil does not contain a large amount of iodine, cases of congenital iodine deficiency syndrome were very abundant and even considered genetically caused. As the variety of food sources dramatically increased in Europe and North America and the populations became less completely dependent on locally grown food, the prevalence of endemic goitre diminished. This is supported by a 1979 WHO publication which concluded that \"changes in the origin of food supplies may account for the otherwise unexplained disappearance of endemic goitre from a number of localities during the past 50 years\".",
"title": "History"
},
{
"paragraph_id": 13,
"text": "The early 20th century saw the discovery of the relationships of neurological impairment with hypothyroidism due to iodine deficiency. Both have been largely eliminated in the developed world.",
"title": "History"
},
{
"paragraph_id": 14,
"text": "The term cretin was originally used to describe a person affected by this condition, but, as with words such as spastic and lunatic, it underwent pejoration and is now considered derogatory and inappropriate. Cretin became a medical term in the 18th century, from an Occitan and an Alpine French expression, prevalent in a region where persons with such a condition were especially common (see below); it saw wide medical use in the 19th and early 20th centuries, and was a \"tick box\" category on Victorian-era census forms in the UK. The term spread more widely in popular English as a markedly derogatory term for a person who behaves stupidly. Because of its pejorative connotations in popular speech, current usage among health care professionals has abandoned the noun \"cretin\" referring to a person. The noun cretinism, referring to the condition, still occurs in medical literature and textbooks but its use is waning.",
"title": "Terminology"
},
{
"paragraph_id": 15,
"text": "The etymology of cretin is uncertain. Several hypotheses exist. The most common derivation provided in English dictionaries is from the Alpine French dialect pronunciation of the word Chrétien (\"(a) Christian\"), which was a greeting there. According to the Oxford English Dictionary, the translation of the French term into \"human creature\" implies that the label \"Christian\" is a reminder of the humanity of the affected, in contrast to brute beasts. Other sources suggest that Christian describes the person's \"Christ-like\" inability to sin, stemming, in such cases, from an incapacity to distinguish right from wrong.",
"title": "Terminology"
},
{
"paragraph_id": 16,
"text": "Other speculative etymologies have been offered:",
"title": "Terminology"
},
{
"paragraph_id": 17,
"text": "Media related to Congenital iodine deficiency syndrome at Wikimedia Commons",
"title": "External links"
}
] | Congenital iodine deficiency syndrome (CIDS) is a medical condition present at birth marked by impaired physical and mental development, due to insufficient thyroid hormone (hypothyroidism) often caused by insufficient dietary iodine during pregnancy. It is one cause of underactive thyroid function at birth, called congenital hypothyroidism, historically referred to as cretinism (obsolete). If untreated, it results in impairment of both physical and mental development. Symptoms may include goiter, poor length growth in infants, reduced adult stature, thickened skin, hair loss, enlarged tongue, a protruding abdomen; delayed bone maturation and puberty in children; and mental deterioration, neurological impairment, impeded ovulation, and infertility in adults. In developed countries, thyroid function testing of newborns has assured that in those affected, treatment with the thyroid hormone thyroxine is begun promptly. This screening and treatment have virtually eliminated the consequences of the disease. | 2001-09-15T12:05:15Z | 2023-10-17T16:00:58Z | [
"Template:Medical resources",
"Template:Infobox medical condition (new)",
"Template:Legend",
"Template:Dead link",
"Template:Webarchive",
"Template:Cbignore",
"Template:Redirect",
"Template:Convert",
"Template:Cite journal",
"Template:Commons category-inline",
"Template:See also",
"Template:Cite web",
"Template:Cite book",
"Template:Reflist",
"Template:Authority control",
"Template:Div col",
"Template:Div col end",
"Template:Citation needed"
] | https://en.wikipedia.org/wiki/Congenital_iodine_deficiency_syndrome |
6,353 | Cretin | Cretin may refer to: | [
{
"paragraph_id": 0,
"text": "Cretin may refer to:",
"title": ""
}
] | Cretin may refer to: An archaic term for a patient with congenital iodine deficiency syndrome (cretinism)
A pejorative term, similar to idiot | 2001-09-15T12:08:50Z | 2023-08-20T21:18:33Z | [
"Template:Wiktionary",
"Template:Disambiguation"
] | https://en.wikipedia.org/wiki/Cretin |
6,354 | Council of Trent | The Council of Trent (Latin: Concilium Tridentinum), held between 1545 and 1563 in Trent (or Trento), now in northern Italy, was the 19th ecumenical council of the Catholic Church. Prompted by the Protestant Reformation at the time, it has been described as the embodiment of the Counter-Reformation.
The Council issued key statements and clarifications of the Church's doctrine and teachings, including scripture, the biblical canon, sacred tradition, original sin, justification, salvation, the sacraments, the Mass, and the veneration of saints and also issued condemnations of what it defined to be heresies committed by proponents of Protestantism. The consequences of the Council were also significant with regard to the Church's liturgy and censorship.
The Council met for twenty-five sessions between 13 December 1545 and 4 December 1563. Pope Paul III, who convoked the Council, oversaw the first eight sessions (1545–47), while the twelfth to sixteenth sessions (1551–52) were overseen by Pope Julius III and the seventeenth to twenty-fifth sessions (1562–63) by Pope Pius IV. More than three hundred years passed until the next ecumenical council, the First Vatican Council, was convened in 1869.
On 15 March 1517, the Fifth Council of the Lateran closed its activities with a number of reform proposals (on the selection of bishops, taxation, censorship and preaching) but not on the new major problems that confronted the Church in Germany and other parts of Europe. A few months later, on 31 October 1517, Martin Luther issued his 95 Theses in Wittenberg.
Luther's position on ecumenical councils shifted over time, but in 1520 he appealed to the German princes to oppose the papal Church at the time, if necessary with a council in Germany, open and free of the Papacy. After the Pope condemned in Exsurge Domine fifty-two of Luther's theses as heresy, German opinion considered a council the best method to reconcile existing differences. German Catholics, diminished in number, hoped for a council to clarify matters.
It took a generation for the council to materialise, partly due to papal fears over potentially renewing a schism over conciliarism; partly because Lutherans demanded the exclusion of the papacy from the Council; partly because of ongoing political rivalries between France and the Holy Roman Empire; and partly due to the Turkish dangers in the Mediterranean. Under Pope Clement VII (1523–34), mutinous troops many whom were Lutheran belonging to the Catholic Holy Roman Emperor Charles V sacked Papal Rome in 1527, "raping, killing, burning, stealing, the like had not been seen since the Vandals". Saint Peter's Basilica and the Sistine Chapel were used for horses. Pope Clement, fearful of the potential for more violence, delayed calling the Council.
Charles V strongly favoured a council but needed the support of King Francis I of France, who attacked him militarily. Francis I generally opposed a general council due to partial support of the Protestant cause within France. Charles’ younger brother Ferdinand of Austria, who ruled a huge swath of territory in central Europe, agreed in 1532 to the Nuremberg Religious Peace granting religious liberty to the Protestants, and in 1533 he further complicated matters when suggesting a general council to include both Catholic and Protestant rulers of Europe that would devise a compromise between the two theological systems. This proposal met the opposition of the Pope for it gave recognition to Protestants and also elevated the secular Princes of Europe above the clergy on church matters. Faced with a Turkish attack, Charles held the support of the Protestant German rulers, all of whom delayed the opening of the Council of Trent.
In the to-and-fro of medieval politics, Pope Pius II, in his bull Execrabilis (1460) and his reply to the University of Cologne (1463), had set aside the theory of the supremacy of general councils laid down by the Council of Constance, which had also called for frequent ecumenical councils every ten years to cope with the backlog of reform and heresies.
Martin Luther had appealed for a general council, in response to the Papal bull Exsurge Domine of Pope Leo X (1520). In 1522 German diets joined in the appeal, with Charles V seconding and pressing for a council as a means of reunifying the Church and settling the Reformation controversies. Pope Clement VII (1523–1534) was vehemently against the idea of a council, agreeing with Francis I of France.
The history of the council is divided into three distinct periods: 1545–1549, 1551–1552 and 1562–1563.
The number of attending members in the three periods varied considerably. The council was small to begin with, opening with only about 30 bishops. It increased toward the close, but never reached the number of the First Council of Nicaea (which had 318 members) nor of the First Vatican Council (which numbered 744). The decrees were signed in 1563 by 255 members, the highest attendance of the whole council, including four papal legates, two cardinals, three patriarchs, twenty-five archbishops, and 168 bishops, two-thirds of whom were Italians. The Italian and Spanish prelates were vastly preponderant in power and numbers. At the passage of the most important decrees, not more than sixty prelates were present. Although most Protestants did not attend, ambassadors and theologians of Brandenburg, Württemberg, and Strasbourg attended having been granted an improved safe conduct.
Pope Paul III (1534–1549), seeing that the Protestant Reformation was no longer confined to a few preachers, but had won over various princes, especially in Germany, to its ideas, desired a council. Yet when he proposed the idea to his cardinals, it was almost unanimously opposed. Nonetheless, he sent nuncios throughout Europe to propose the idea. Paul III issued a decree for a general council to be held in Mantua, Italy, to begin on 23 May 1537. Martin Luther wrote the Smalcald Articles in preparation for the general council. The Smalcald Articles were designed to sharply define where the Lutherans could and could not compromise. The council was ordered by the Emperor and Pope Paul III to convene in Mantua on 23 May 1537.
It failed to convene after another war broke out between France and Charles V, resulting in a non-attendance of French prelates. Protestants refused to attend as well. Financial difficulties in Mantua led the Pope in the autumn of 1537 to move the council to Vicenza, where participation was poor. The Council was postponed indefinitely on 21 May 1539.
Pope Paul III then initiated several internal Church reforms while Emperor Charles V convened with Protestants and Cardinal Gasparo Contarini at the Diet of Regensburg, to reconcile differences. Mediating and conciliatory formulations were developed on certain topics. In particular, a two-part doctrine of justification was formulated that would later be rejected at Trent. Unity failed between Catholic and Protestant representatives "because of different concepts of Church and justification".
However, the council was delayed until 1545 and, as it happened, convened right before Luther's death. Unable, however, to resist the urging of Charles V, the pope, after proposing Mantua as the place of meeting, convened the council at Trent (at that time ruled by a prince-bishop under the Holy Roman Empire), on 13 December 1545; the Pope's decision to transfer it to Bologna in March 1547 on the pretext of avoiding a plague failed to take effect and the Council was indefinitely prorogued on 17 September 1549. None of the three popes reigning over the duration of the council ever attended, which had been a condition of Charles V. Papal legates were appointed to represent the Papacy.
Reopened at Trent on 1 May 1551 by the convocation of Pope Julius III (1550–1555), it was broken up by the sudden victory of Maurice, Elector of Saxony over Emperor Charles V and his march into surrounding state of Tirol on 28 April 1552. There was no hope of reassembling the council while the very anti-Protestant Paul IV was Pope.
During the second period, the Protestants present asked for a renewed discussion on points already defined and for bishops to be released from their oaths of allegiance to the Pope. When the last period began, all intentions of conciliating the Protestants was gone and the Jesuits had become a strong force. This last period was begun especially as an attempt to prevent the formation of a general council including Protestants, as had been demanded by some in France.
The council was reconvened by Pope Pius IV (1559–1565) for the last time, meeting from 18 January 1562 at Santa Maria Maggiore, and continued until its final adjournment on 4 December 1563. It closed with a series of ritual acclamations honouring the reigning Pope, the Popes who had convoked the Council, the emperor and the kings who had supported it, the papal legates, the cardinals, the ambassadors present, and the bishops, followed by acclamations of acceptance of the faith of the Council and its decrees, and of anathema for all heretics.
The French monarchy boycotted the entire council until the last minute when a delegation led by Charles de Guise, Cardinal of Lorraine finally arrived in November 1562. The first outbreak of the French Wars of Religion had occurred earlier in the year and the French Church, facing a significant and powerful Protestant minority in France, experienced iconoclasm violence regarding the use of sacred images. Such concerns were not primary in the Italian and Spanish Churches. The last-minute inclusion of a decree on sacred images was a French initiative, and the text, never discussed on the floor of the council or referred to council theologians, was based on a French draft.
The main objectives of the council were twofold:
Specific issues that were discussed included:
The doctrinal decisions of the council were set forth in decrees (decreta), which are divided into chapters (capita), which contain the positive statement of the conciliar dogmas, and into short canons (canones), which condemn incorrect views (often a Protestant-associated notion stated in an extreme form) with the concluding anathema sit ("let him be anathema" i.e., excluded from the society of the faithful).
The consequences of the Council were also significant with regard to the Church's liturgy and practices. In its decrees, the Council made the Latin Vulgate the official biblical text of the Roman Church (without prejudice to the original texts in Hebrew and Greek, nor to other traditional translations of the Church, but favoring the Latin language over vernacular translations, such as the controversial English-language Tyndale Bible). In doing so, they commissioned the creation of a revised and standardized Vulgate in light of textual criticism, although this was not achieved until the 1590s. The Council also officially affirmed (for the second time at an ecumenical council) the traditional Catholic Canon of biblical books in response to the increasing Protestant exclusion of the deuterocanonical books. The former dogmatic affirmation of the Canonical books was at the Council of Florence in the 1441 bull Cantate Domino, as affirmed by Pope Leo XIII in his 1893 encyclical Providentissimus Deus (#20). In 1565, a year after the Council finished its work, Pius IV issued the Tridentine Creed (after Tridentum, Trent's Latin name) and his successor Pius V then issued the Roman Catechism and revisions of the Breviary and Missal in, respectively, 1566, 1568 and 1570. These, in turn, led to the codification of the Tridentine Mass, which remained the Church's primary form of the Mass for the next four hundred years.
The doctrinal acts are as follows:
After reaffirming the Niceno-Constantinopolitan Creed (third session), the decree was passed (fourth session) confirming that the deuterocanonical books were on a par with the other books of the canon (against Luther's placement of these books in the Apocrypha of his edition) and coordinating church tradition with the Scriptures as a rule of faith. The Vulgate translation was affirmed to be authoritative for the text of Scripture.
Justification (sixth session) was declared to be offered upon the basis of human cooperation with divine grace (synergism) as opposed to the typical Protestant doctrine of passive reception of grace (monergism). Understanding the Protestant "faith alone" doctrine to be one of simple human confidence in Divine Mercy, the Council rejected the "vain confidence" of the Protestants, stating that no one can know who has received the grace of God. Furthermore, the Council affirmed—against some Protestants—that the grace of God can be forfeited through mortal sin.
The greatest weight in the Council's decrees is given to the sacraments. The seven sacraments were reaffirmed and the Eucharist pronounced to be a true propitiatory sacrifice as well as a sacrament, in which the bread and wine were consecrated into the Eucharist (thirteenth and twenty-second sessions). The term transubstantiation was used by the Council, but the specific Aristotelian explanation given by Scholasticism was not cited as dogmatic. Instead, the decree states that Christ is "really, truly, substantially present" in the consecrated forms. The sacrifice of the Mass was to be offered for dead and living alike and in giving to the apostles the command "do this in remembrance of me," Christ conferred upon them a sacerdotal power. The practice of withholding the cup from the laity was confirmed (twenty-first session) as one which the Church Fathers had commanded for good and sufficient reasons; yet in certain cases the Pope was made the supreme arbiter as to whether the rule should be strictly maintained.
Ordination (twenty-third session) was defined to imprint an indelible character on the soul. The priesthood of the New Testament takes the place of the Levitical priesthood. To the performance of its functions, the consent of the people is not necessary.
In the decrees on marriage (twenty-fourth session) the excellence of the celibate state was reaffirmed, concubinage condemned and the validity of marriage made dependent upon the wedding taking place before a priest and two witnesses, although the lack of a requirement for parental consent ended a debate that had proceeded from the 12th century. In the case of a divorce, the right of the innocent party to marry again was denied so long as the other party was alive, even if the other party had committed adultery. However the council "refused … to assert the necessity or usefulness of clerical celibacy".
In the twenty-fifth and last session, the doctrines of purgatory, the invocation of saints and the veneration of relics were reaffirmed, as was also the efficacy of indulgences as dispensed by the Church according to the power given her, but with some cautionary recommendations, and a ban on the sale of indulgences. Short and rather inexplicit passages concerning religious images, were to have great impact on the development of Catholic Church art. Much more than the Second Council of Nicaea (787), the Council fathers of Trent stressed the pedagogical purpose of Christian images.
On the language of the Mass, "contrary to what is often said", the council condemned the insistence that only vernacular languages must be used, while affirming on the use of Latin for the Roman rite. However, elements of the Prône, the vernacular catechetical preaching service common in the medieval High Mass (and some extra-liturgical situations) became mandatory for Sundays and feast days (fifth session, chapter 2).
The council appointed, in 1562 (eighteenth session), a commission to prepare a list of forbidden books (Index Librorum Prohibitorum), but it later left the matter to the Pope. The preparation of a catechism and the revision of the Breviary and Missal were also left to the pope. The catechism embodied the council's far-reaching results, including reforms and definitions of the sacraments, the Scriptures, church dogma, and duties of the clergy.
On adjourning, the Council asked the supreme pontiff to ratify all its decrees and definitions. This petition was complied with by Pope Pius IV, on 26 January 1564, in the papal bull, Benedictus Deus, which enjoins strict obedience upon all Catholics and forbids, under pain of ex-communication, all unauthorised interpretation, reserving this to the Pope alone and threatens the disobedient with "the indignation of Almighty God and of his blessed apostles, Peter and Paul." Pope Pius appointed a commission of cardinals to assist him in interpreting and enforcing the decrees.
The Index Librorum Prohibitorum was announced in 1564 and the following books were issued with the papal imprimatur: the Profession of the Tridentine Faith and the Tridentine Catechism (1566), the Breviary (1568), the Missal (1570) and the Vulgate (1590 and then 1592).
The decrees of the council were acknowledged in Italy, Portugal, Poland and by the Catholic princes of Germany at the Diet of Augsburg in 1566. Philip II of Spain accepted them for Spain, the Netherlands and Sicily inasmuch as they did not infringe the royal prerogative. In France, they were officially recognised by the king only in their doctrinal parts. Although the disciplinary or moral reformatory decrees were never published by the throne, they received official recognition at provincial synods and were enforced by the bishops. Holy Roman Emperors Ferdinand I and Maximilian II never recognized the existence of any of the decrees. No attempt was made to introduce it into England. Pius IV sent the decrees to Mary, Queen of Scots, with a letter dated 13 June 1564, requesting that she publish them in Scotland, but she dared not do it in the face of John Knox and the Reformation.
These decrees were later supplemented by the First Vatican Council of 1870.
A comprehensive history is found in Hubert Jedin's The History of the Council of Trent (Geschichte des Konzils von Trient) with about 2,500 pages in four volumes: The History of the Council of Trent: The fight for a Council (Vol I, 1951); The History of the Council of Trent: The first Sessions in Trent (1545–1547) (Vol II, 1957); The History of the Council of Trent: Sessions in Bologna 1547–1548 and Trento 1551–1552 (Vol III, 1970, 1998); The History of the Council of Trent: Third Period and Conclusion (Vol IV, 1976).
The canons and decrees of the council have been published very often and in many languages. The first issue was by Paulus Manutius (Rome, 1564). Commonly used Latin editions are by Judocus Le Plat (Antwerp, 1779) and by Johann Friedrich von Schulte and Aemilius Ludwig Richter (Leipzig, 1853). Other editions are in vol. vii. of the Acta et decreta conciliorum recentiorum. Collectio Lacensis (7 vols., Freiburg, 1870–90), reissued as independent volume (1892); Concilium Tridentinum: Diariorum, actorum, epistularum, … collectio, ed. Sebastianus Merkle (4 vols., Freiburg, 1901 sqq.); as well as Mansi, Concilia, xxxv. 345 sqq. Note also Carl Mirbt, Quellen, 2d ed, pp. 202–255. An English edition is by James Waterworth (London, 1848; With Essays on the External and Internal History of the Council).
The original acts and debates of the council, as prepared by its general secretary, Bishop Angelo Massarelli, in six large folio volumes, are deposited in the Vatican Library and remained there unpublished for more than 300 years and were brought to light, though only in part, by Augustin Theiner, priest of the oratory (d. 1874), in Acta genuina sancti et oecumenici Concilii Tridentini nunc primum integre edita (2 vols., Leipzig, 1874).
Most of the official documents and private reports, however, which bear upon the council, were made known in the 16th century and since. The most complete collection of them is that of J. Le Plat, Monumentorum ad historicam Concilii Tridentini collectio (7 vols., Leuven, 1781–87). New materials(Vienna, 1872); by JJI von Döllinger (Ungedruckte Berichte und Tagebücher zur Geschichte des Concilii von Trient) (2 parts, Nördlingen, 1876); and August von Druffel, Monumenta Tridentina (Munich, 1884–97).
Out of 87 books written between 1546 and 1564 attacking the Council of Trent, 41 were written by Pier Paolo Vergerio, a former papal nuncio turned Protestant Reformer. The 1565–73 Examen decretorum Concilii Tridentini (Examination of the Council of Trent) by Martin Chemnitz was the main Lutheran response to the Council of Trent. Making extensive use of scripture and patristic sources, it was presented in response to a polemical writing which Diogo de Payva de Andrada had directed against Chemnitz. The Examen had four parts: Volume I examined sacred scripture, free will, original sin, justification, and good works. Volume II examined the sacraments, including baptism, confirmation, the sacrament of the Eucharist, communion under both kinds, the Mass, penance, extreme unction, holy orders, and matrimony. Volume III examined virginity, celibacy, purgatory, and the invocation of saints. Volume IV examined the relics of the saints, images, indulgences, fasting, the distinction of foods, and festivals.
In response, Andrada wrote the five-part Defensio Tridentinæ fidei, which was published posthumously in 1578. However, the Defensio did not circulate as extensively as the Examen, nor were any full translations ever published. A French translation of the Examen by Eduard Preuss was published in 1861. German translations were published in 1861, 1884, and 1972. In English, a complete translation by Fred Kramer drawing from the original Latin and the 1861 German was published beginning in 1971. | [
{
"paragraph_id": 0,
"text": "The Council of Trent (Latin: Concilium Tridentinum), held between 1545 and 1563 in Trent (or Trento), now in northern Italy, was the 19th ecumenical council of the Catholic Church. Prompted by the Protestant Reformation at the time, it has been described as the embodiment of the Counter-Reformation.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The Council issued key statements and clarifications of the Church's doctrine and teachings, including scripture, the biblical canon, sacred tradition, original sin, justification, salvation, the sacraments, the Mass, and the veneration of saints and also issued condemnations of what it defined to be heresies committed by proponents of Protestantism. The consequences of the Council were also significant with regard to the Church's liturgy and censorship.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The Council met for twenty-five sessions between 13 December 1545 and 4 December 1563. Pope Paul III, who convoked the Council, oversaw the first eight sessions (1545–47), while the twelfth to sixteenth sessions (1551–52) were overseen by Pope Julius III and the seventeenth to twenty-fifth sessions (1562–63) by Pope Pius IV. More than three hundred years passed until the next ecumenical council, the First Vatican Council, was convened in 1869.",
"title": ""
},
{
"paragraph_id": 3,
"text": "On 15 March 1517, the Fifth Council of the Lateran closed its activities with a number of reform proposals (on the selection of bishops, taxation, censorship and preaching) but not on the new major problems that confronted the Church in Germany and other parts of Europe. A few months later, on 31 October 1517, Martin Luther issued his 95 Theses in Wittenberg.",
"title": "Background information"
},
{
"paragraph_id": 4,
"text": "Luther's position on ecumenical councils shifted over time, but in 1520 he appealed to the German princes to oppose the papal Church at the time, if necessary with a council in Germany, open and free of the Papacy. After the Pope condemned in Exsurge Domine fifty-two of Luther's theses as heresy, German opinion considered a council the best method to reconcile existing differences. German Catholics, diminished in number, hoped for a council to clarify matters.",
"title": "Background information"
},
{
"paragraph_id": 5,
"text": "It took a generation for the council to materialise, partly due to papal fears over potentially renewing a schism over conciliarism; partly because Lutherans demanded the exclusion of the papacy from the Council; partly because of ongoing political rivalries between France and the Holy Roman Empire; and partly due to the Turkish dangers in the Mediterranean. Under Pope Clement VII (1523–34), mutinous troops many whom were Lutheran belonging to the Catholic Holy Roman Emperor Charles V sacked Papal Rome in 1527, \"raping, killing, burning, stealing, the like had not been seen since the Vandals\". Saint Peter's Basilica and the Sistine Chapel were used for horses. Pope Clement, fearful of the potential for more violence, delayed calling the Council.",
"title": "Background information"
},
{
"paragraph_id": 6,
"text": "Charles V strongly favoured a council but needed the support of King Francis I of France, who attacked him militarily. Francis I generally opposed a general council due to partial support of the Protestant cause within France. Charles’ younger brother Ferdinand of Austria, who ruled a huge swath of territory in central Europe, agreed in 1532 to the Nuremberg Religious Peace granting religious liberty to the Protestants, and in 1533 he further complicated matters when suggesting a general council to include both Catholic and Protestant rulers of Europe that would devise a compromise between the two theological systems. This proposal met the opposition of the Pope for it gave recognition to Protestants and also elevated the secular Princes of Europe above the clergy on church matters. Faced with a Turkish attack, Charles held the support of the Protestant German rulers, all of whom delayed the opening of the Council of Trent.",
"title": "Background information"
},
{
"paragraph_id": 7,
"text": "In the to-and-fro of medieval politics, Pope Pius II, in his bull Execrabilis (1460) and his reply to the University of Cologne (1463), had set aside the theory of the supremacy of general councils laid down by the Council of Constance, which had also called for frequent ecumenical councils every ten years to cope with the backlog of reform and heresies.",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 8,
"text": "Martin Luther had appealed for a general council, in response to the Papal bull Exsurge Domine of Pope Leo X (1520). In 1522 German diets joined in the appeal, with Charles V seconding and pressing for a council as a means of reunifying the Church and settling the Reformation controversies. Pope Clement VII (1523–1534) was vehemently against the idea of a council, agreeing with Francis I of France.",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 9,
"text": "The history of the council is divided into three distinct periods: 1545–1549, 1551–1552 and 1562–1563.",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 10,
"text": "The number of attending members in the three periods varied considerably. The council was small to begin with, opening with only about 30 bishops. It increased toward the close, but never reached the number of the First Council of Nicaea (which had 318 members) nor of the First Vatican Council (which numbered 744). The decrees were signed in 1563 by 255 members, the highest attendance of the whole council, including four papal legates, two cardinals, three patriarchs, twenty-five archbishops, and 168 bishops, two-thirds of whom were Italians. The Italian and Spanish prelates were vastly preponderant in power and numbers. At the passage of the most important decrees, not more than sixty prelates were present. Although most Protestants did not attend, ambassadors and theologians of Brandenburg, Württemberg, and Strasbourg attended having been granted an improved safe conduct.",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 11,
"text": "Pope Paul III (1534–1549), seeing that the Protestant Reformation was no longer confined to a few preachers, but had won over various princes, especially in Germany, to its ideas, desired a council. Yet when he proposed the idea to his cardinals, it was almost unanimously opposed. Nonetheless, he sent nuncios throughout Europe to propose the idea. Paul III issued a decree for a general council to be held in Mantua, Italy, to begin on 23 May 1537. Martin Luther wrote the Smalcald Articles in preparation for the general council. The Smalcald Articles were designed to sharply define where the Lutherans could and could not compromise. The council was ordered by the Emperor and Pope Paul III to convene in Mantua on 23 May 1537.",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 12,
"text": "It failed to convene after another war broke out between France and Charles V, resulting in a non-attendance of French prelates. Protestants refused to attend as well. Financial difficulties in Mantua led the Pope in the autumn of 1537 to move the council to Vicenza, where participation was poor. The Council was postponed indefinitely on 21 May 1539.",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 13,
"text": "Pope Paul III then initiated several internal Church reforms while Emperor Charles V convened with Protestants and Cardinal Gasparo Contarini at the Diet of Regensburg, to reconcile differences. Mediating and conciliatory formulations were developed on certain topics. In particular, a two-part doctrine of justification was formulated that would later be rejected at Trent. Unity failed between Catholic and Protestant representatives \"because of different concepts of Church and justification\".",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 14,
"text": "However, the council was delayed until 1545 and, as it happened, convened right before Luther's death. Unable, however, to resist the urging of Charles V, the pope, after proposing Mantua as the place of meeting, convened the council at Trent (at that time ruled by a prince-bishop under the Holy Roman Empire), on 13 December 1545; the Pope's decision to transfer it to Bologna in March 1547 on the pretext of avoiding a plague failed to take effect and the Council was indefinitely prorogued on 17 September 1549. None of the three popes reigning over the duration of the council ever attended, which had been a condition of Charles V. Papal legates were appointed to represent the Papacy.",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 15,
"text": "Reopened at Trent on 1 May 1551 by the convocation of Pope Julius III (1550–1555), it was broken up by the sudden victory of Maurice, Elector of Saxony over Emperor Charles V and his march into surrounding state of Tirol on 28 April 1552. There was no hope of reassembling the council while the very anti-Protestant Paul IV was Pope.",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 16,
"text": "During the second period, the Protestants present asked for a renewed discussion on points already defined and for bishops to be released from their oaths of allegiance to the Pope. When the last period began, all intentions of conciliating the Protestants was gone and the Jesuits had become a strong force. This last period was begun especially as an attempt to prevent the formation of a general council including Protestants, as had been demanded by some in France.",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 17,
"text": "The council was reconvened by Pope Pius IV (1559–1565) for the last time, meeting from 18 January 1562 at Santa Maria Maggiore, and continued until its final adjournment on 4 December 1563. It closed with a series of ritual acclamations honouring the reigning Pope, the Popes who had convoked the Council, the emperor and the kings who had supported it, the papal legates, the cardinals, the ambassadors present, and the bishops, followed by acclamations of acceptance of the faith of the Council and its decrees, and of anathema for all heretics.",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 18,
"text": "The French monarchy boycotted the entire council until the last minute when a delegation led by Charles de Guise, Cardinal of Lorraine finally arrived in November 1562. The first outbreak of the French Wars of Religion had occurred earlier in the year and the French Church, facing a significant and powerful Protestant minority in France, experienced iconoclasm violence regarding the use of sacred images. Such concerns were not primary in the Italian and Spanish Churches. The last-minute inclusion of a decree on sacred images was a French initiative, and the text, never discussed on the floor of the council or referred to council theologians, was based on a French draft.",
"title": "Occasion, sessions, and attendance"
},
{
"paragraph_id": 19,
"text": "The main objectives of the council were twofold:",
"title": "Objectives and overall results"
},
{
"paragraph_id": 20,
"text": "Specific issues that were discussed included:",
"title": "Objectives and overall results"
},
{
"paragraph_id": 21,
"text": "The doctrinal decisions of the council were set forth in decrees (decreta), which are divided into chapters (capita), which contain the positive statement of the conciliar dogmas, and into short canons (canones), which condemn incorrect views (often a Protestant-associated notion stated in an extreme form) with the concluding anathema sit (\"let him be anathema\" i.e., excluded from the society of the faithful).",
"title": "Objectives and overall results"
},
{
"paragraph_id": 22,
"text": "The consequences of the Council were also significant with regard to the Church's liturgy and practices. In its decrees, the Council made the Latin Vulgate the official biblical text of the Roman Church (without prejudice to the original texts in Hebrew and Greek, nor to other traditional translations of the Church, but favoring the Latin language over vernacular translations, such as the controversial English-language Tyndale Bible). In doing so, they commissioned the creation of a revised and standardized Vulgate in light of textual criticism, although this was not achieved until the 1590s. The Council also officially affirmed (for the second time at an ecumenical council) the traditional Catholic Canon of biblical books in response to the increasing Protestant exclusion of the deuterocanonical books. The former dogmatic affirmation of the Canonical books was at the Council of Florence in the 1441 bull Cantate Domino, as affirmed by Pope Leo XIII in his 1893 encyclical Providentissimus Deus (#20). In 1565, a year after the Council finished its work, Pius IV issued the Tridentine Creed (after Tridentum, Trent's Latin name) and his successor Pius V then issued the Roman Catechism and revisions of the Breviary and Missal in, respectively, 1566, 1568 and 1570. These, in turn, led to the codification of the Tridentine Mass, which remained the Church's primary form of the Mass for the next four hundred years.",
"title": "Objectives and overall results"
},
{
"paragraph_id": 23,
"text": "The doctrinal acts are as follows:",
"title": "Decrees"
},
{
"paragraph_id": 24,
"text": "After reaffirming the Niceno-Constantinopolitan Creed (third session), the decree was passed (fourth session) confirming that the deuterocanonical books were on a par with the other books of the canon (against Luther's placement of these books in the Apocrypha of his edition) and coordinating church tradition with the Scriptures as a rule of faith. The Vulgate translation was affirmed to be authoritative for the text of Scripture.",
"title": "Decrees"
},
{
"paragraph_id": 25,
"text": "Justification (sixth session) was declared to be offered upon the basis of human cooperation with divine grace (synergism) as opposed to the typical Protestant doctrine of passive reception of grace (monergism). Understanding the Protestant \"faith alone\" doctrine to be one of simple human confidence in Divine Mercy, the Council rejected the \"vain confidence\" of the Protestants, stating that no one can know who has received the grace of God. Furthermore, the Council affirmed—against some Protestants—that the grace of God can be forfeited through mortal sin.",
"title": "Decrees"
},
{
"paragraph_id": 26,
"text": "The greatest weight in the Council's decrees is given to the sacraments. The seven sacraments were reaffirmed and the Eucharist pronounced to be a true propitiatory sacrifice as well as a sacrament, in which the bread and wine were consecrated into the Eucharist (thirteenth and twenty-second sessions). The term transubstantiation was used by the Council, but the specific Aristotelian explanation given by Scholasticism was not cited as dogmatic. Instead, the decree states that Christ is \"really, truly, substantially present\" in the consecrated forms. The sacrifice of the Mass was to be offered for dead and living alike and in giving to the apostles the command \"do this in remembrance of me,\" Christ conferred upon them a sacerdotal power. The practice of withholding the cup from the laity was confirmed (twenty-first session) as one which the Church Fathers had commanded for good and sufficient reasons; yet in certain cases the Pope was made the supreme arbiter as to whether the rule should be strictly maintained.",
"title": "Decrees"
},
{
"paragraph_id": 27,
"text": "Ordination (twenty-third session) was defined to imprint an indelible character on the soul. The priesthood of the New Testament takes the place of the Levitical priesthood. To the performance of its functions, the consent of the people is not necessary.",
"title": "Decrees"
},
{
"paragraph_id": 28,
"text": "In the decrees on marriage (twenty-fourth session) the excellence of the celibate state was reaffirmed, concubinage condemned and the validity of marriage made dependent upon the wedding taking place before a priest and two witnesses, although the lack of a requirement for parental consent ended a debate that had proceeded from the 12th century. In the case of a divorce, the right of the innocent party to marry again was denied so long as the other party was alive, even if the other party had committed adultery. However the council \"refused … to assert the necessity or usefulness of clerical celibacy\".",
"title": "Decrees"
},
{
"paragraph_id": 29,
"text": "In the twenty-fifth and last session, the doctrines of purgatory, the invocation of saints and the veneration of relics were reaffirmed, as was also the efficacy of indulgences as dispensed by the Church according to the power given her, but with some cautionary recommendations, and a ban on the sale of indulgences. Short and rather inexplicit passages concerning religious images, were to have great impact on the development of Catholic Church art. Much more than the Second Council of Nicaea (787), the Council fathers of Trent stressed the pedagogical purpose of Christian images.",
"title": "Decrees"
},
{
"paragraph_id": 30,
"text": "On the language of the Mass, \"contrary to what is often said\", the council condemned the insistence that only vernacular languages must be used, while affirming on the use of Latin for the Roman rite. However, elements of the Prône, the vernacular catechetical preaching service common in the medieval High Mass (and some extra-liturgical situations) became mandatory for Sundays and feast days (fifth session, chapter 2).",
"title": "Decrees"
},
{
"paragraph_id": 31,
"text": "The council appointed, in 1562 (eighteenth session), a commission to prepare a list of forbidden books (Index Librorum Prohibitorum), but it later left the matter to the Pope. The preparation of a catechism and the revision of the Breviary and Missal were also left to the pope. The catechism embodied the council's far-reaching results, including reforms and definitions of the sacraments, the Scriptures, church dogma, and duties of the clergy.",
"title": "Decrees"
},
{
"paragraph_id": 32,
"text": "On adjourning, the Council asked the supreme pontiff to ratify all its decrees and definitions. This petition was complied with by Pope Pius IV, on 26 January 1564, in the papal bull, Benedictus Deus, which enjoins strict obedience upon all Catholics and forbids, under pain of ex-communication, all unauthorised interpretation, reserving this to the Pope alone and threatens the disobedient with \"the indignation of Almighty God and of his blessed apostles, Peter and Paul.\" Pope Pius appointed a commission of cardinals to assist him in interpreting and enforcing the decrees.",
"title": "Decrees"
},
{
"paragraph_id": 33,
"text": "The Index Librorum Prohibitorum was announced in 1564 and the following books were issued with the papal imprimatur: the Profession of the Tridentine Faith and the Tridentine Catechism (1566), the Breviary (1568), the Missal (1570) and the Vulgate (1590 and then 1592).",
"title": "Decrees"
},
{
"paragraph_id": 34,
"text": "The decrees of the council were acknowledged in Italy, Portugal, Poland and by the Catholic princes of Germany at the Diet of Augsburg in 1566. Philip II of Spain accepted them for Spain, the Netherlands and Sicily inasmuch as they did not infringe the royal prerogative. In France, they were officially recognised by the king only in their doctrinal parts. Although the disciplinary or moral reformatory decrees were never published by the throne, they received official recognition at provincial synods and were enforced by the bishops. Holy Roman Emperors Ferdinand I and Maximilian II never recognized the existence of any of the decrees. No attempt was made to introduce it into England. Pius IV sent the decrees to Mary, Queen of Scots, with a letter dated 13 June 1564, requesting that she publish them in Scotland, but she dared not do it in the face of John Knox and the Reformation.",
"title": "Decrees"
},
{
"paragraph_id": 35,
"text": "These decrees were later supplemented by the First Vatican Council of 1870.",
"title": "Decrees"
},
{
"paragraph_id": 36,
"text": "A comprehensive history is found in Hubert Jedin's The History of the Council of Trent (Geschichte des Konzils von Trient) with about 2,500 pages in four volumes: The History of the Council of Trent: The fight for a Council (Vol I, 1951); The History of the Council of Trent: The first Sessions in Trent (1545–1547) (Vol II, 1957); The History of the Council of Trent: Sessions in Bologna 1547–1548 and Trento 1551–1552 (Vol III, 1970, 1998); The History of the Council of Trent: Third Period and Conclusion (Vol IV, 1976).",
"title": "Publication of documents"
},
{
"paragraph_id": 37,
"text": "The canons and decrees of the council have been published very often and in many languages. The first issue was by Paulus Manutius (Rome, 1564). Commonly used Latin editions are by Judocus Le Plat (Antwerp, 1779) and by Johann Friedrich von Schulte and Aemilius Ludwig Richter (Leipzig, 1853). Other editions are in vol. vii. of the Acta et decreta conciliorum recentiorum. Collectio Lacensis (7 vols., Freiburg, 1870–90), reissued as independent volume (1892); Concilium Tridentinum: Diariorum, actorum, epistularum, … collectio, ed. Sebastianus Merkle (4 vols., Freiburg, 1901 sqq.); as well as Mansi, Concilia, xxxv. 345 sqq. Note also Carl Mirbt, Quellen, 2d ed, pp. 202–255. An English edition is by James Waterworth (London, 1848; With Essays on the External and Internal History of the Council).",
"title": "Publication of documents"
},
{
"paragraph_id": 38,
"text": "The original acts and debates of the council, as prepared by its general secretary, Bishop Angelo Massarelli, in six large folio volumes, are deposited in the Vatican Library and remained there unpublished for more than 300 years and were brought to light, though only in part, by Augustin Theiner, priest of the oratory (d. 1874), in Acta genuina sancti et oecumenici Concilii Tridentini nunc primum integre edita (2 vols., Leipzig, 1874).",
"title": "Publication of documents"
},
{
"paragraph_id": 39,
"text": "Most of the official documents and private reports, however, which bear upon the council, were made known in the 16th century and since. The most complete collection of them is that of J. Le Plat, Monumentorum ad historicam Concilii Tridentini collectio (7 vols., Leuven, 1781–87). New materials(Vienna, 1872); by JJI von Döllinger (Ungedruckte Berichte und Tagebücher zur Geschichte des Concilii von Trient) (2 parts, Nördlingen, 1876); and August von Druffel, Monumenta Tridentina (Munich, 1884–97).",
"title": "Publication of documents"
},
{
"paragraph_id": 40,
"text": "Out of 87 books written between 1546 and 1564 attacking the Council of Trent, 41 were written by Pier Paolo Vergerio, a former papal nuncio turned Protestant Reformer. The 1565–73 Examen decretorum Concilii Tridentini (Examination of the Council of Trent) by Martin Chemnitz was the main Lutheran response to the Council of Trent. Making extensive use of scripture and patristic sources, it was presented in response to a polemical writing which Diogo de Payva de Andrada had directed against Chemnitz. The Examen had four parts: Volume I examined sacred scripture, free will, original sin, justification, and good works. Volume II examined the sacraments, including baptism, confirmation, the sacrament of the Eucharist, communion under both kinds, the Mass, penance, extreme unction, holy orders, and matrimony. Volume III examined virginity, celibacy, purgatory, and the invocation of saints. Volume IV examined the relics of the saints, images, indulgences, fasting, the distinction of foods, and festivals.",
"title": "Protestant response"
},
{
"paragraph_id": 41,
"text": "In response, Andrada wrote the five-part Defensio Tridentinæ fidei, which was published posthumously in 1578. However, the Defensio did not circulate as extensively as the Examen, nor were any full translations ever published. A French translation of the Examen by Eduard Preuss was published in 1861. German translations were published in 1861, 1884, and 1972. In English, a complete translation by Fred Kramer drawing from the original Latin and the 1861 German was published beginning in 1971.",
"title": "Protestant response"
}
] | The Council of Trent, held between 1545 and 1563 in Trent, now in northern Italy, was the 19th ecumenical council of the Catholic Church. Prompted by the Protestant Reformation at the time, it has been described as the embodiment of the Counter-Reformation. The Council issued key statements and clarifications of the Church's doctrine and teachings, including scripture, the biblical canon, sacred tradition, original sin, justification, salvation, the sacraments, the Mass, and the veneration of saints and also issued condemnations of what it defined to be heresies committed by proponents of Protestantism. The consequences of the Council were also significant with regard to the Church's liturgy and censorship. The Council met for twenty-five sessions between 13 December 1545 and 4 December 1563. Pope Paul III, who convoked the Council, oversaw the first eight sessions (1545–47), while the twelfth to sixteenth sessions (1551–52) were overseen by Pope Julius III and the seventeenth to twenty-fifth sessions (1562–63) by Pope Pius IV. More than three hundred years passed until the next ecumenical council, the First Vatican Council, was convened in 1869. | 2001-09-15T12:20:41Z | 2023-12-19T22:17:20Z | [
"Template:Catholic Counter-Reformation",
"Template:Lang-la",
"Template:Webarchive",
"Template:Spoken Wikipedia",
"Template:Hlist",
"Template:Authority control",
"Template:Ecumenical councils of the Catholic Church",
"Template:Rp",
"Template:Ecumenical councils",
"Template:More citations needed",
"Template:ISBN",
"Template:Cite journal",
"Template:Canon law",
"Template:Commons category",
"Template:Tridentine Latin Mass",
"Template:Citation",
"Template:Cite web",
"Template:Cite book",
"Template:Wikiquote",
"Template:CathEncy",
"Template:Clarify",
"Template:Dubious",
"Template:Reflist",
"Template:History of the Catholic Church",
"Template:Short description",
"Template:Infobox Ecumenical council",
"Template:Schaff-Herzog",
"Template:Wikisource portal"
] | https://en.wikipedia.org/wiki/Council_of_Trent |
6,355 | Chloroplast | A chloroplast (/ˈklɔːrəˌplæst, -plɑːst/) is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water in the cells. The ATP and NADPH is then used to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from one, in unicellular algae, up to 100 in plants like Arabidopsis and wheat.
A chloroplast is characterized by its two membranes and a high concentration of chlorophyll. Other plastid types, such as the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photosynthesis.
Chloroplasts are highly dynamic—they circulate and are moved around within plant cells, and occasionally pinch in two to reproduce. Their behavior is strongly influenced by environmental factors like light color and intensity. Chloroplasts, like mitochondria, contain their own DNA, which is thought to be inherited from their ancestor—a photosynthetic cyanobacterium that was engulfed by an early eukaryotic cell. Chloroplasts cannot be made by the plant cell and must be inherited by each daughter cell during cell division.
With one exception (the amoeboid Paulinella chromatophora), all chloroplasts can probably be traced back to a single endosymbiotic event, when a cyanobacterium was engulfed by the eukaryote. Despite this, chloroplasts can be found in an extremely wide set of organisms, some not even directly related to each other—a consequence of many secondary and even tertiary endosymbiotic events.
The word chloroplast is derived from the Greek words chloros (χλωρός), which means green, and plastes (πλάστης), which means "the one who forms".
The first definitive description of a chloroplast (Chlorophyllkörnen, "grain of chlorophyll") was given by Hugo von Mohl in 1837 as discrete bodies within the green plant cell. In 1883, Andreas Franz Wilhelm Schimper would name these bodies as "chloroplastids" (Chloroplastiden). In 1884, Eduard Strasburger adopted the term "chloroplasts" (Chloroplasten).
Chloroplasts are one of many types of organelles in the plant cell. They are considered to have evolved from endosymbiotic cyanobacteria. Mitochondria are thought to have come from a similar endosymbiosis event, where an aerobic prokaryote was engulfed. This origin of chloroplasts was first suggested by the Russian biologist Konstantin Mereschkowski in 1905 after Andreas Franz Wilhelm Schimper observed in 1883 that chloroplasts closely resemble cyanobacteria. Chloroplasts are only found in plants, algae, and three species of amoeba – Paulinella chromatophora, P. micropora, and marine P. longichromatophora.
Chloroplasts are considered endosymbiotic Cyanobacteria. Cyanobacteria are sometimes called blue-green algae even though they are prokaryotes. They are a diverse phylum of gram-negative bacteria capable of carrying out photosynthesis. Cyanobacteria also contain a peptidoglycan cell wall, which is thicker than in other gram-negative bacteria, and which is located between their two cell membranes. Like chloroplasts, they have thylakoids within them. On the thylakoid membranes are photosynthetic pigments, including chlorophyll a. Phycobilins are also common cyanobacterial pigments, usually organized into hemispherical phycobilisomes attached to the outside of the thylakoid membranes (phycobilins are not shared with all chloroplasts though).
Somewhere between 1 and 2 billion years ago, a free-living cyanobacterium entered an early eukaryotic cell, either as food or as an internal parasite, but managed to escape the phagocytic vacuole it was contained in. The two innermost lipid-bilayer membranes that surround all chloroplasts correspond to the outer and inner membranes of the ancestral cyanobacterium's gram negative cell wall, and not the phagosomal membrane from the host, which was probably lost. The new cellular resident quickly became an advantage, providing food for the eukaryotic host, which allowed it to live within it. Over time, the cyanobacterium was assimilated, and many of its genes were lost or transferred to the nucleus of the host. From genomes that probably originally contained over 3000 genes only about 130 genes remain in the chloroplasts of contemporary plants. Some of its proteins were then synthesized in the cytoplasm of the host cell, and imported back into the chloroplast (formerly the cyanobacterium). Separately, somewhere about 90–140 million years ago, it happened again and led to the amoeboid Paulinella chromatophora.
This event is called endosymbiosis, or "cell living inside another cell with a mutual benefit for both". The external cell is commonly referred to as the host while the internal cell is called the endosymbiont.
Chloroplasts are believed to have arisen after mitochondria, since all eukaryotes contain mitochondria, but not all have chloroplasts. This is called serial endosymbiosis—an early eukaryote engulfing the mitochondrion ancestor, and some descendants of it then engulfing the chloroplast ancestor, creating a cell with both chloroplasts and mitochondria.
Whether or not primary chloroplasts came from a single endosymbiotic event, or many independent engulfments across various eukaryotic lineages, has long been debated. It is now generally held that organisms with primary chloroplasts share a single ancestor that took in a cyanobacterium 600–2000 million years ago. It has been proposed this the closest living relative of this bacterium is Gloeomargarita lithophora. The exception is the amoeboid Paulinella chromatophora, which descends from an ancestor that took in a Prochlorococcus cyanobacterium 90–500 million years ago.
These chloroplasts, which can be traced back directly to a cyanobacterial ancestor, are known as primary plastids ("plastid" in this context means almost the same thing as chloroplast). All primary chloroplasts belong to one of four chloroplast lineages—the glaucophyte chloroplast lineage, the amoeboid Paulinella chromatophora lineage, the rhodophyte (red algal) chloroplast lineage, or the chloroplastidan (green) chloroplast lineage. The rhodophyte and chloroplastidan lineages are the largest, with chloroplastidan (green) being the one that contains the land plants.
Usually the endosymbiosis event is considered to have occurred in the Archaeplastida, within which the glaucophyta being the possible earliest diverging lineage. The glaucophyte chloroplast group is the smallest of the three primary chloroplast lineages, being found in only 13 species, and is thought to be the one that branched off the earliest. Glaucophytes have chloroplasts that retain a peptidoglycan wall between their double membranes, like their cyanobacterial parent. For this reason, glaucophyte chloroplasts are also known as 'muroplasts' (besides 'cyanoplasts' or 'cyanelles'). Glaucophyte chloroplasts also contain concentric unstacked thylakoids, which surround a carboxysome – an icosahedral structure that glaucophyte chloroplasts and cyanobacteria keep their carbon fixation enzyme RuBisCO in. The starch that they synthesize collects outside the chloroplast. Like cyanobacteria, glaucophyte and rhodophyte chloroplast thylakoids are studded with light collecting structures called phycobilisomes. For these reasons, glaucophyte chloroplasts are considered a primitive intermediate between cyanobacteria and the more evolved chloroplasts in red algae and plants.
The rhodophyte, or red algae chloroplast group is another large and diverse chloroplast lineage. Rhodophyte chloroplasts are also called rhodoplasts, literally "red chloroplasts".
Rhodoplasts have a double membrane with an intermembrane space and phycobilin pigments organized into phycobilisomes on the thylakoid membranes, preventing their thylakoids from stacking. Some contain pyrenoids. Rhodoplasts have chlorophyll a and phycobilins for photosynthetic pigments; the phycobilin phycoerythrin is responsible for giving many red algae their distinctive red color. However, since they also contain the blue-green chlorophyll a and other pigments, many are reddish to purple from the combination. The red phycoerytherin pigment is an adaptation to help red algae catch more sunlight in deep water—as such, some red algae that live in shallow water have less phycoerythrin in their rhodoplasts, and can appear more greenish. Rhodoplasts synthesize a form of starch called floridean starch, which collects into granules outside the rhodoplast, in the cytoplasm of the red alga.
The chloroplastida chloroplasts, or green chloroplasts, are another large, highly diverse primary chloroplast lineage. Their host organisms are commonly known as green algae and land plants. They differ from glaucophyte and red algal chloroplasts in that they have lost their phycobilisomes, and contain chlorophyll b instead. Most green chloroplasts are (obviously) green, though some aren't, like some forms of Hæmatococcus pluvialis, due to accessory pigments that override the chlorophylls' green colors. Chloroplastida chloroplasts have lost the peptidoglycan wall between their double membrane, leaving an intermembrane space. Some plants seem to have kept the genes for the synthesis of the peptidoglycan layer, though they've been repurposed for use in chloroplast division instead.
Most of the chloroplasts depicted in this article are green chloroplasts.
Green algae and plants keep their starch inside their chloroplasts, and in plants and some algae, the chloroplast thylakoids are arranged in grana stacks. Some green algal chloroplasts contain a structure called a pyrenoid, which is functionally similar to the glaucophyte carboxysome in that it is where RuBisCO and CO2 are concentrated in the chloroplast.
Helicosporidium is a genus of nonphotosynthetic parasitic green algae that is thought to contain a vestigial chloroplast. Genes from a chloroplast and nuclear genes indicating the presence of a chloroplast have been found in Helicosporidium even if nobody's seen the chloroplast itself.
While most chloroplasts originate from that first set of endosymbiotic events, Paulinella chromatophora is an exception that acquired a photosynthetic cyanobacterial endosymbiont more recently. It is not clear whether that symbiont is closely related to the ancestral chloroplast of other eukaryotes. Being in the early stages of endosymbiosis, Paulinella chromatophora can offer some insights into how chloroplasts evolved. Paulinella cells contain one or two sausage-shaped blue-green photosynthesizing structures called chromatophores, descended from the cyanobacterium Synechococcus. Chromatophores cannot survive outside their host. Chromatophore DNA is about a million base pairs long, containing around 850 protein-encoding genes—far less than the three million base pair Synechococcus genome, but much larger than the approximately 150,000 base pair genome of the more assimilated chloroplast. Chromatophores have transferred much less of their DNA to the nucleus of their host. About 0.3–0.8% of the nuclear DNA in Paulinella is from the chromatophore, compared with 11–14% from the chloroplast in plants.
It is now established that Chromalveolata is paraphyletic to Rhizaria.
Edit
Many other organisms obtained chloroplasts from the primary chloroplast lineages through secondary endosymbiosis—engulfing a red or green alga that contained a chloroplast. These chloroplasts are known as secondary plastids.
While primary chloroplasts have a double membrane from their cyanobacterial ancestor, secondary chloroplasts have additional membranes outside of the original two, as a result of the secondary endosymbiotic event, when a nonphotosynthetic eukaryote engulfed a chloroplast-containing alga but failed to digest it—much like the cyanobacterium at the beginning of this story. The engulfed alga was broken down, leaving only its chloroplast, and sometimes its cell membrane and nucleus, forming a chloroplast with three or four membranes—the two cyanobacterial membranes, sometimes the eaten alga's cell membrane, and the phagosomal vacuole from the host's cell membrane.
The genes in the phagocytosed eukaryote's nucleus are often transferred to the secondary host's nucleus. Cryptomonads and chlorarachniophytes retain the phagocytosed eukaryote's nucleus, an object called a nucleomorph, located between the second and third membranes of the chloroplast.
All secondary chloroplasts come from green and red algae—no secondary chloroplasts from glaucophytes have been observed, probably because glaucophytes are relatively rare in nature, making them less likely to have been taken up by another eukaryote.
Green algae have been taken up by the euglenids, chlorarachniophytes, a lineage of dinoflagellates, and possibly the ancestor of the CASH lineage (cryptomonads, alveolates, stramenopiles and haptophytes) in three or four separate engulfments. Many green algal derived chloroplasts contain pyrenoids, but unlike chloroplasts in their green algal ancestors, storage product collects in granules outside the chloroplast.
Euglenophytes are a group of common flagellated protists that contain chloroplasts derived from a green alga. Euglenophyte chloroplasts have three membranes—it is thought that the membrane of the primary endosymbiont was lost, leaving the cyanobacterial membranes, and the secondary host's phagosomal membrane. Euglenophyte chloroplasts have a pyrenoid and thylakoids stacked in groups of three. Photosynthetic product is stored in the form of paramylon, which is contained in membrane-bound granules in the cytoplasm of the euglenophyte.
Chlorarachniophytes /ˌklɔːrəˈræknioʊˌfaɪts/ are a rare group of organisms that also contain chloroplasts derived from green algae, though their story is more complicated than that of the euglenophytes. The ancestor of chlorarachniophytes is thought to have been a eukaryote with a red algal derived chloroplast. It is then thought to have lost its first red algal chloroplast, and later engulfed a green alga, giving it its second, green algal derived chloroplast.
Chlorarachniophyte chloroplasts are bounded by four membranes, except near the cell membrane, where the chloroplast membranes fuse into a double membrane. Their thylakoids are arranged in loose stacks of three. Chlorarachniophytes have a form of polysaccharide called chrysolaminarin, which they store in the cytoplasm, often collected around the chloroplast pyrenoid, which bulges into the cytoplasm.
Chlorarachniophyte chloroplasts are notable because the green alga they are derived from has not been completely broken down—its nucleus still persists as a nucleomorph found between the second and third chloroplast membranes—the periplastid space, which corresponds to the green alga's cytoplasm.
Lepidodinium viride and its close relatives are dinophytes (see below) that lost their original peridinin chloroplast and replaced it with a green algal derived chloroplast (more specifically, a prasinophyte). Lepidodinium is the only dinophyte that has a chloroplast that's not from the rhodoplast lineage. The chloroplast is surrounded by two membranes and has no nucleomorph—all the nucleomorph genes have been transferred to the dinophyte nucleus. The endosymbiotic event that led to this chloroplast was serial secondary endosymbiosis rather than tertiary endosymbiosis—the endosymbiont was a green alga containing a primary chloroplast (making a secondary chloroplast).
Cryptophytes, or cryptomonads are a group of algae that contain a red-algal derived chloroplast. Cryptophyte chloroplasts contain a nucleomorph that superficially resembles that of the chlorarachniophytes. Cryptophyte chloroplasts have four membranes, the outermost of which is continuous with the rough endoplasmic reticulum. They synthesize ordinary starch, which is stored in granules found in the periplastid space—outside the original double membrane, in the place that corresponds to the red alga's cytoplasm. Inside cryptophyte chloroplasts is a pyrenoid and thylakoids in stacks of two.
Their chloroplasts do not have phycobilisomes, but they do have phycobilin pigments which they keep in their thylakoid space, rather than anchored on the outside of their thylakoid membranes.
Cryptophytes may have played a key role in the spreading of red algal based chloroplasts.
Haptophytes are similar and closely related to cryptophytes or heterokontophytes. Their chloroplasts lack a nucleomorph, their thylakoids are in stacks of three, and they synthesize chrysolaminarin sugar, which they store completely outside of the chloroplast, in the cytoplasm of the haptophyte.
The heterokontophytes, also known as the stramenopiles, are a very large and diverse group of eukaryotes. The photoautotrophic lineage, Ochrophyta, including the diatoms and the brown algae, golden algae, and yellow-green algae, also contains red algal derived chloroplasts.
Heterokont chloroplasts are very similar to haptophyte chloroplasts, containing a pyrenoid, triplet thylakoids, and with some exceptions, having four layer plastidic envelope, the outermost epiplastid membrane connected to the endoplasmic reticulum. Like haptophytes, heterokontophytes store sugar in chrysolaminarin granules in the cytoplasm. Heterokontophyte chloroplasts contain chlorophyll a and with a few exceptions chlorophyll c, but also have carotenoids which give them their many colors.
The alveolates are a major clade of unicellular eukaryotes of both autotrophic and heterotrophic members. The most notable shared characteristic is the presence of cortical (outer-region) alveoli (sacs). These are flattened vesicles (sacs) packed into a continuous layer just under the membrane and supporting it, typically forming a flexible pellicle (thin skin). In dinoflagellates they often form armor plates. Many members contain a red-algal derived plastid. One notable characteristic of this diverse group is the frequent loss of photosynthesis. However, a majority of these heterotrophs continue to process a non-photosynthetic plastid.
Apicomplexans are a group of alveolates. Like the helicosproidia, they're parasitic, and have a nonphotosynthetic chloroplast. They were once thought to be related to the helicosproidia, but it is now known that the helicosproida are green algae rather than part of the CASH lineage. The apicomplexans include Plasmodium, the malaria parasite. Many apicomplexans keep a vestigial red algal derived chloroplast called an apicoplast, which they inherited from their ancestors. Other apicomplexans like Cryptosporidium have lost the chloroplast completely. Apicomplexans store their energy in amylopectin granules that are located in their cytoplasm, even though they are nonphotosynthetic.
Apicoplasts have lost all photosynthetic function, and contain no photosynthetic pigments or true thylakoids. They are bounded by four membranes, but the membranes are not connected to the endoplasmic reticulum. The fact that apicomplexans still keep their nonphotosynthetic chloroplast around demonstrates how the chloroplast carries out important functions other than photosynthesis. Plant chloroplasts provide plant cells with many important things besides sugar, and apicoplasts are no different—they synthesize fatty acids, isopentenyl pyrophosphate, iron-sulfur clusters, and carry out part of the heme pathway. This makes the apicoplast an attractive target for drugs to cure apicomplexan-related diseases. The most important apicoplast function is isopentenyl pyrophosphate synthesis—in fact, apicomplexans die when something interferes with this apicoplast function, and when apicomplexans are grown in an isopentenyl pyrophosphate-rich medium, they dump the organelle.
The Chromerida is a newly discovered group of algae from Australian corals which comprises some close photosynthetic relatives of the apicomplexans. The first member, Chromera velia, was discovered and first isolated in 2001. The discovery of Chromera velia with similar structure to the apicomplexans, provides an important link in the evolutionary history of the apicomplexans and dinophytes. Their plastids have four membranes, lack chlorophyll c and use the type II form of RuBisCO obtained from a horizontal transfer event.
The dinoflagellates are yet another very large and diverse group of protists, around half of which are (at least partially) photosynthetic.
Most dinophyte chloroplasts are secondary red algal derived chloroplasts. Many other dinophytes have lost the chloroplast (becoming the nonphotosynthetic kind of dinoflagellate), or replaced it though tertiary endosymbiosis—the engulfment of another eukaryotic algae containing a red algal derived chloroplast. Others replaced their original chloroplast with a green algal derived one.
Most dinophyte chloroplasts contain form II RuBisCO, at least the photosynthetic pigments chlorophyll a, chlorophyll c2, beta-carotene, and at least one dinophyte-unique xanthophyll (peridinin, dinoxanthin, or diadinoxanthin), giving many a golden-brown color. All dinophytes store starch in their cytoplasm, and most have chloroplasts with thylakoids arranged in stacks of three.
The most common dinophyte chloroplast is the peridinin-type chloroplast, characterized by the carotenoid pigment peridinin in their chloroplasts, along with chlorophyll a and chlorophyll c2. Peridinin is not found in any other group of chloroplasts. The peridinin chloroplast is bounded by three membranes (occasionally two), having lost the red algal endosymbiont's original cell membrane. The outermost membrane is not connected to the endoplasmic reticulum. They contain a pyrenoid, and have triplet-stacked thylakoids. Starch is found outside the chloroplast. An important feature of these chloroplasts is that their chloroplast DNA is highly reduced and fragmented into many small circles. Most of the genome has migrated to the nucleus, and only critical photosynthesis-related genes remain in the chloroplast.
The peridinin chloroplast is thought to be the dinophytes' "original" chloroplast, which has been lost, reduced, replaced, or has company in several other dinophyte lineages.
The fucoxanthin dinophyte lineages (including Karlodinium and Karenia) lost their original red algal derived chloroplast, and replaced it with a new chloroplast derived from a haptophyte endosymbiont. Karlodinium and Karenia probably took up different heterokontophytes. Because the haptophyte chloroplast has four membranes, tertiary endosymbiosis would be expected to create a six membraned chloroplast, adding the haptophyte's cell membrane and the dinophyte's phagosomal vacuole. However, the haptophyte was heavily reduced, stripped of a few membranes and its nucleus, leaving only its chloroplast (with its original double membrane), and possibly one or two additional membranes around it.
Fucoxanthin-containing chloroplasts are characterized by having the pigment fucoxanthin (actually 19′-hexanoyloxy-fucoxanthin and/or 19′-butanoyloxy-fucoxanthin) and no peridinin. Fucoxanthin is also found in haptophyte chloroplasts, providing evidence of ancestry.
Some dinophytes, like Kryptoperidinium and Durinskia, have a diatom (heterokontophyte)-derived chloroplast. These chloroplasts are bounded by up to five membranes, (depending on whether the entire diatom endosymbiont is counted as the chloroplast, or just the red algal derived chloroplast inside it). The diatom endosymbiont has been reduced relatively little—it still retains its original mitochondria, and has endoplasmic reticulum, ribosomes, a nucleus, and of course, red algal derived chloroplasts—practically a complete cell, all inside the host's endoplasmic reticulum lumen. However the diatom endosymbiont can't store its own food—its storage polysaccharide is found in granules in the dinophyte host's cytoplasm instead. The diatom endosymbiont's nucleus is present, but it probably can't be called a nucleomorph because it shows no sign of genome reduction, and might have even been expanded. Diatoms have been engulfed by dinoflagellates at least three times.
The diatom endosymbiont is bounded by a single membrane, inside it are chloroplasts with four membranes. Like the diatom endosymbiont's diatom ancestor, the chloroplasts have triplet thylakoids and pyrenoids.
In some of these genera, the diatom endosymbiont's chloroplasts aren't the only chloroplasts in the dinophyte. The original three-membraned peridinin chloroplast is still around, converted to an eyespot.
In some groups of mixotrophic protists, like some dinoflagellates (e.g. Dinophysis), chloroplasts are separated from a captured alga and used temporarily. These klepto chloroplasts may only have a lifetime of a few days and are then replaced.
Members of the genus Dinophysis have a phycobilin-containing chloroplast taken from a cryptophyte. However, the cryptophyte is not an endosymbiont—only the chloroplast seems to have been taken, and the chloroplast has been stripped of its nucleomorph and outermost two membranes, leaving just a two-membraned chloroplast. Cryptophyte chloroplasts require their nucleomorph to maintain themselves, and Dinophysis species grown in cell culture alone cannot survive, so it is possible (but not confirmed) that the Dinophysis chloroplast is a kleptoplast—if so, Dinophysis chloroplasts wear out and Dinophysis species must continually engulf cryptophytes to obtain new chloroplasts to replace the old ones.
Chloroplasts, like other types of plastid, contain a genome separate from that in the cell nucleus. The existence of chloroplast DNA (cpDNA) was identified biochemically in 1959, and confirmed by electron microscopy in 1962. The discoveries that the chloroplast contains ribosomes and performs protein synthesis revealed that the chloroplast is genetically semi-autonomous. Chloroplast DNA was first sequenced in 1986. Since then, hundreds of chloroplast DNAs from various species have been sequenced, but they are mostly those of land plants and green algae—glaucophytes, red algae, and other algal groups are extremely underrepresented, potentially introducing some bias in views of "typical" chloroplast DNA structure and content.
With few exceptions, most chloroplasts have their entire chloroplast genome combined into a single large circular DNA molecule, typically 120,000–170,000 base pairs long. They can have a contour length of around 30–60 micrometers, and have a mass of about 80–130 million daltons.
While usually thought of as a circular molecule, there is some evidence that chloroplast DNA molecules more often take on a linear shape.
Many chloroplast DNAs contain two inverted repeats, which separate a long single copy section (LSC) from a short single copy section (SSC). While a given pair of inverted repeats are rarely completely identical, they are always very similar to each other, apparently resulting from concerted evolution.
The inverted repeats vary wildly in length, ranging from 4,000 to 25,000 base pairs long each and containing as few as four or as many as over 150 genes. Inverted repeats in plants tend to be at the upper end of this range, each being 20,000–25,000 base pairs long.
The inverted repeat regions are highly conserved among land plants, and accumulate few mutations. Similar inverted repeats exist in the genomes of cyanobacteria and the other two chloroplast lineages (glaucophyta and rhodophyceae), suggesting that they predate the chloroplast, though some chloroplast DNAs have since lost or flipped the inverted repeats (making them direct repeats). It is possible that the inverted repeats help stabilize the rest of the chloroplast genome, as chloroplast DNAs which have lost some of the inverted repeat segments tend to get rearranged more.
New chloroplasts may contain up to 100 copies of their DNA, though the number of chloroplast DNA copies decreases to about 15–20 as the chloroplasts age. They are usually packed into nucleoids, which can contain several identical chloroplast DNA rings. Many nucleoids can be found in each chloroplast. In primitive red algae, the chloroplast DNA nucleoids are clustered in the center of the chloroplast, while in green plants and green algae, the nucleoids are dispersed throughout the stroma.
Though chloroplast DNA is not associated with true histones, in red algae, similar proteins that tightly pack each chloroplast DNA ring into a nucleoid have been found.
In chloroplasts of the moss Physcomitrella patens, the DNA mismatch repair protein Msh1 interacts with the recombinational repair proteins RecA and RecG to maintain chloroplast genome stability. In chloroplasts of the plant Arabidopsis thaliana the RecA protein maintains the integrity of the chloroplast's DNA by a process that likely involves the recombinational repair of DNA damage.
The mechanism for chloroplast DNA (cpDNA) replication has not been conclusively determined, but two main models have been proposed. Scientists have attempted to observe chloroplast replication via electron microscopy since the 1970s. The results of the microscopy experiments led to the idea that chloroplast DNA replicates using a double displacement loop (D-loop). As the D-loop moves through the circular DNA, it adopts a theta intermediary form, also known as a Cairns replication intermediate, and completes replication with a rolling circle mechanism. Transcription starts at specific points of origin. Multiple replication forks open up, allowing replication machinery to transcribe the DNA. As replication continues, the forks grow and eventually converge. The new cpDNA structures separate, creating daughter cpDNA chromosomes.
In addition to the early microscopy experiments, this model is also supported by the amounts of deamination seen in cpDNA. Deamination occurs when an amino group is lost and is a mutation that often results in base changes. When adenine is deaminated, it becomes hypoxanthine. Hypoxanthine can bind to cytosine, and when the XC base pair is replicated, it becomes a GC (thus, an A → G base change).
In cpDNA, there are several A → G deamination gradients. DNA becomes susceptible to deamination events when it is single stranded. When replication forks form, the strand not being copied is single stranded, and thus at risk for A → G deamination. Therefore, gradients in deamination indicate that replication forks were most likely present and the direction that they initially opened (the highest gradient is most likely nearest the start site because it was single stranded for the longest amount of time). This mechanism is still the leading theory today; however, a second theory suggests that most cpDNA is actually linear and replicates through homologous recombination. It further contends that only a minority of the genetic material is kept in circular chromosomes while the rest is in branched, linear, or other complex structures.
One of competing model for cpDNA replication asserts that most cpDNA is linear and participates in homologous recombination and replication structures similar to the linear and circular DNA structures of bacteriophage T4. It has been established that some plants have linear cpDNA, such as maize, and that more species still contain complex structures that scientists do not yet understand. When the original experiments on cpDNA were performed, scientists did notice linear structures; however, they attributed these linear forms to broken circles. If the branched and complex structures seen in cpDNA experiments are real and not artifacts of concatenated circular DNA or broken circles, then a D-loop mechanism of replication is insufficient to explain how those structures would replicate. At the same time, homologous recombination does not expand the multiple A --> G gradients seen in plastomes. Because of the failure to explain the deamination gradient as well as the numerous plant species that have been shown to have circular cpDNA, the predominant theory continues to hold that most cpDNA is circular and most likely replicates via a D loop mechanism.
The chloroplast genome most commonly includes around 100 genes that code for a variety of things, mostly to do with the protein pipeline and photosynthesis. As in prokaryotes, genes in chloroplast DNA are organized into operons. Unlike prokaryotic DNA molecules, chloroplast DNA molecules contain introns (plant mitochondrial DNAs do too, but not human mtDNAs).
Among land plants, the contents of the chloroplast genome are fairly similar.
Over time, many parts of the chloroplast genome were transferred to the nuclear genome of the host, a process called endosymbiotic gene transfer. As a result, the chloroplast genome is heavily reduced compared to that of free-living cyanobacteria. Chloroplasts may contain 60–100 genes whereas cyanobacteria often have more than 1500 genes in their genome. Recently, a plastid without a genome was found, demonstrating chloroplasts can lose their genome during endosymbiotic the gene transfer process.
Endosymbiotic gene transfer is how we know about the lost chloroplasts in many CASH lineages. Even if a chloroplast is eventually lost, the genes it donated to the former host's nucleus persist, providing evidence for the lost chloroplast's existence. For example, while diatoms (a heterokontophyte) now have a red algal derived chloroplast, the presence of many green algal genes in the diatom nucleus provide evidence that the diatom ancestor had a green algal derived chloroplast at some point, which was subsequently replaced by the red chloroplast.
In land plants, some 11–14% of the DNA in their nuclei can be traced back to the chloroplast, up to 18% in Arabidopsis, corresponding to about 4,500 protein-coding genes. There have been a few recent transfers of genes from the chloroplast DNA to the nuclear genome in land plants.
Of the approximately 3000 proteins found in chloroplasts, some 95% of them are encoded by nuclear genes. Many of the chloroplast's protein complexes consist of subunits from both the chloroplast genome and the host's nuclear genome. As a result, protein synthesis must be coordinated between the chloroplast and the nucleus. The chloroplast is mostly under nuclear control, though chloroplasts can also give out signals regulating gene expression in the nucleus, called retrograde signaling. Recent research indicates that parts of the retrograde signaling network once considered characteristic for land plants emerged already in an algal progenitor, integrating into co-expressed cohorts of genes in the closest algal relatives of land plants.
Protein synthesis within chloroplasts relies on two RNA polymerases. One is coded by the chloroplast DNA, the other is of nuclear origin. The two RNA polymerases may recognize and bind to different kinds of promoters within the chloroplast genome. The ribosomes in chloroplasts are similar to bacterial ribosomes.
Because so many chloroplast genes have been moved to the nucleus, many proteins that would originally have been translated in the chloroplast are now synthesized in the cytoplasm of the plant cell. These proteins must be directed back to the chloroplast, and imported through at least two chloroplast membranes.
Curiously, around half of the protein products of transferred genes aren't even targeted back to the chloroplast. Many became exaptations, taking on new functions like participating in cell division, protein routing, and even disease resistance. A few chloroplast genes found new homes in the mitochondrial genome—most became nonfunctional pseudogenes, though a few tRNA genes still work in the mitochondrion. Some transferred chloroplast DNA protein products get directed to the secretory pathway, though many secondary plastids are bounded by an outermost membrane derived from the host's cell membrane, and therefore topologically outside of the cell because to reach the chloroplast from the cytosol, the cell membrane must be crossed, which signifies entrance into the extracellular space. In those cases, chloroplast-targeted proteins do initially travel along the secretory pathway.
Because the cell acquiring a chloroplast already had mitochondria (and peroxisomes, and a cell membrane for secretion), the new chloroplast host had to develop a unique protein targeting system to avoid having chloroplast proteins being sent to the wrong organelle.
In most, but not all cases, nuclear-encoded chloroplast proteins are translated with a cleavable transit peptide that's added to the N-terminus of the protein precursor. Sometimes the transit sequence is found on the C-terminus of the protein, or within the functional part of the protein.
After a chloroplast polypeptide is synthesized on a ribosome in the cytosol, an enzyme specific to chloroplast proteins phosphorylates, or adds a phosphate group to many (but not all) of them in their transit sequences. Phosphorylation helps many proteins bind the polypeptide, keeping it from folding prematurely. This is important because it prevents chloroplast proteins from assuming their active form and carrying out their chloroplast functions in the wrong place—the cytosol. At the same time, they have to keep just enough shape so that they can be recognized by the chloroplast. These proteins also help the polypeptide get imported into the chloroplast.
From here, chloroplast proteins bound for the stroma must pass through two protein complexes—the TOC complex, or translocon on the outer chloroplast membrane, and the TIC translocon, or translocon on the inner chloroplast membrane translocon. Chloroplast polypeptide chains probably often travel through the two complexes at the same time, but the TIC complex can also retrieve preproteins lost in the intermembrane space.
In land plants, chloroplasts are generally lens-shaped, 3–10 μm in diameter and 1–3 μm thick. Corn seedling chloroplasts are ≈20 µm in volume. Greater diversity in chloroplast shapes exists among the algae, which often contain a single chloroplast that can be shaped like a net (e.g., Oedogonium), a cup (e.g., Chlamydomonas), a ribbon-like spiral around the edges of the cell (e.g., Spirogyra), or slightly twisted bands at the cell edges (e.g., Sirogonium). Some algae have two chloroplasts in each cell; they are star-shaped in Zygnema, or may follow the shape of half the cell in order Desmidiales. In some algae, the chloroplast takes up most of the cell, with pockets for the nucleus and other organelles, for example, some species of Chlorella have a cup-shaped chloroplast that occupies much of the cell.
All chloroplasts have at least three membrane systems—the outer chloroplast membrane, the inner chloroplast membrane, and the thylakoid system. Chloroplasts that are the product of secondary endosymbiosis may have additional membranes surrounding these three. Inside the outer and inner chloroplast membranes is the chloroplast stroma, a semi-gel-like fluid that makes up much of a chloroplast's volume, and in which the thylakoid system floats.
There are some common misconceptions about the outer and inner chloroplast membranes. The fact that chloroplasts are surrounded by a double membrane is often cited as evidence that they are the descendants of endosymbiotic cyanobacteria. This is often interpreted as meaning the outer chloroplast membrane is the product of the host's cell membrane infolding to form a vesicle to surround the ancestral cyanobacterium—which is not true—both chloroplast membranes are homologous to the cyanobacterium's original double membranes.
The chloroplast double membrane is also often compared to the mitochondrial double membrane. This is not a valid comparison—the inner mitochondria membrane is used to run proton pumps and carry out oxidative phosphorylation across to generate ATP energy. The only chloroplast structure that can considered analogous to it is the internal thylakoid system. Even so, in terms of "in-out", the direction of chloroplast H ion flow is in the opposite direction compared to oxidative phosphorylation in mitochondria. In addition, in terms of function, the inner chloroplast membrane, which regulates metabolite passage and synthesizes some materials, has no counterpart in the mitochondrion.
The outer chloroplast membrane is a semi-porous membrane that small molecules and ions can easily diffuse across. However, it is not permeable to larger proteins, so chloroplast polypeptides being synthesized in the cell cytoplasm must be transported across the outer chloroplast membrane by the TOC complex, or translocon on the outer chloroplast membrane.
The chloroplast membranes sometimes protrude out into the cytoplasm, forming a stromule, or stroma-containing tubule. Stromules are very rare in chloroplasts, and are much more common in other plastids like chromoplasts and amyloplasts in petals and roots, respectively. They may exist to increase the chloroplast's surface area for cross-membrane transport, because they are often branched and tangled with the endoplasmic reticulum. When they were first observed in 1962, some plant biologists dismissed the structures as artifactual, claiming that stromules were just oddly shaped chloroplasts with constricted regions or dividing chloroplasts. However, there is a growing body of evidence that stromules are functional, integral features of plant cell plastids, not merely artifacts.
Usually, a thin intermembrane space about 10–20 nanometers thick exists between the outer and inner chloroplast membranes.
Glaucophyte algal chloroplasts have a peptidoglycan layer between the chloroplast membranes. It corresponds to the peptidoglycan cell wall of their cyanobacterial ancestors, which is located between their two cell membranes. These chloroplasts are called muroplasts (from Latin "mura", meaning "wall"). Other chloroplasts were assumed to have lost the cyanobacterial wall, leaving an intermembrane space between the two chloroplast envelope membranes, but has since been found also in moss, lycophytes and ferns.
The inner chloroplast membrane borders the stroma and regulates passage of materials in and out of the chloroplast. After passing through the TOC complex in the outer chloroplast membrane, polypeptides must pass through the TIC complex (translocon on the inner chloroplast membrane) which is located in the inner chloroplast membrane.
In addition to regulating the passage of materials, the inner chloroplast membrane is where fatty acids, lipids, and carotenoids are synthesized.
Some chloroplasts contain a structure called the chloroplast peripheral reticulum. It is often found in the chloroplasts of C4 plants, though it has also been found in some C3 angiosperms, and even some gymnosperms. The chloroplast peripheral reticulum consists of a maze of membranous tubes and vesicles continuous with the inner chloroplast membrane that extends into the internal stromal fluid of the chloroplast. Its purpose is thought to be to increase the chloroplast's surface area for cross-membrane transport between its stroma and the cell cytoplasm. The small vesicles sometimes observed may serve as transport vesicles to shuttle stuff between the thylakoids and intermembrane space.
The protein-rich, alkaline, aqueous fluid within the inner chloroplast membrane and outside of the thylakoid space is called the stroma, which corresponds to the cytosol of the original cyanobacterium. Nucleoids of chloroplast DNA, chloroplast ribosomes, the thylakoid system with plastoglobuli, starch granules, and many proteins can be found floating around in it. The Calvin cycle, which fixes CO2 into G3P takes place in the stroma.
Chloroplasts have their own ribosomes, which they use to synthesize a small fraction of their proteins. Chloroplast ribosomes are about two-thirds the size of cytoplasmic ribosomes (around 17 nm vs 25 nm). They take mRNAs transcribed from the chloroplast DNA and translate them into protein. While similar to bacterial ribosomes, chloroplast translation is more complex than in bacteria, so chloroplast ribosomes include some chloroplast-unique features.
Small subunit ribosomal RNAs in several Chlorophyta and euglenid chloroplasts lack motifs for Shine-Dalgarno sequence recognition, which is considered essential for translation initiation in most chloroplasts and prokaryotes. Such loss is also rarely observed in other plastids and prokaryotes. An additional 4.5S rRNA with homology to the 3' tail of 23S is found in "higher" plants.
Plastoglobuli (singular plastoglobulus, sometimes spelled plastoglobule(s)), are spherical bubbles of lipids and proteins about 45–60 nanometers across. They are surrounded by a lipid monolayer. Plastoglobuli are found in all chloroplasts, but become more common when the chloroplast is under oxidative stress, or when it ages and transitions into a gerontoplast. Plastoglobuli also exhibit a greater size variation under these conditions. They are also common in etioplasts, but decrease in number as the etioplasts mature into chloroplasts.
Plastoglobuli contain both structural proteins and enzymes involved in lipid synthesis and metabolism. They contain many types of lipids including plastoquinone, vitamin E, carotenoids and chlorophylls.
Plastoglobuli were once thought to be free-floating in the stroma, but it is now thought that they are permanently attached either to a thylakoid or to another plastoglobulus attached to a thylakoid, a configuration that allows a plastoglobulus to exchange its contents with the thylakoid network. In normal green chloroplasts, the vast majority of plastoglobuli occur singularly, attached directly to their parent thylakoid. In old or stressed chloroplasts, plastoglobuli tend to occur in linked groups or chains, still always anchored to a thylakoid.
Plastoglobuli form when a bubble appears between the layers of the lipid bilayer of the thylakoid membrane, or bud from existing plastoglobuli—though they never detach and float off into the stroma. Practically all plastoglobuli form on or near the highly curved edges of the thylakoid disks or sheets. They are also more common on stromal thylakoids than on granal ones.
Starch granules are very common in chloroplasts, typically taking up 15% of the organelle's volume, though in some other plastids like amyloplasts, they can be big enough to distort the shape of the organelle. Starch granules are simply accumulations of starch in the stroma, and are not bounded by a membrane.
Starch granules appear and grow throughout the day, as the chloroplast synthesizes sugars, and are consumed at night to fuel respiration and continue sugar export into the phloem, though in mature chloroplasts, it is rare for a starch granule to be completely consumed or for a new granule to accumulate.
Starch granules vary in composition and location across different chloroplast lineages. In red algae, starch granules are found in the cytoplasm rather than in the chloroplast. In C4 plants, mesophyll chloroplasts, which do not synthesize sugars, lack starch granules.
The chloroplast stroma contains many proteins, though the most common and important is RuBisCO, which is probably also the most abundant protein on the planet. RuBisCO is the enzyme that fixes CO2 into sugar molecules. In C3 plants, RuBisCO is abundant in all chloroplasts, though in C4 plants, it is confined to the bundle sheath chloroplasts, where the Calvin cycle is carried out in C4 plants.
The chloroplasts of some hornworts and algae contain structures called pyrenoids. They are not found in higher plants. Pyrenoids are roughly spherical and highly refractive bodies which are a site of starch accumulation in plants that contain them. They consist of a matrix opaque to electrons, surrounded by two hemispherical starch plates. The starch is accumulated as the pyrenoids mature. In algae with carbon concentrating mechanisms, the enzyme RuBisCO is found in the pyrenoids. Starch can also accumulate around the pyrenoids when CO2 is scarce. Pyrenoids can divide to form new pyrenoids, or be produced "de novo".
Thylakoids (sometimes spelled thylakoïds), are small interconnected sacks which contain the membranes that the light reactions of photosynthesis take place on. The word thylakoid comes from the Greek word thylakos which means "sack".
Suspended within the chloroplast stroma is the thylakoid system, a highly dynamic collection of membranous sacks called thylakoids where chlorophyll is found and the light reactions of photosynthesis happen. In most vascular plant chloroplasts, the thylakoids are arranged in stacks called grana, though in certain C4 plant chloroplasts and some algal chloroplasts, the thylakoids are free floating.
Using a light microscope, it is just barely possible to see tiny green granules—which were named grana. With electron microscopy, it became possible to see the thylakoid system in more detail, revealing it to consist of stacks of flat thylakoids which made up the grana, and long interconnecting stromal thylakoids which linked different grana. In the transmission electron microscope, thylakoid membranes appear as alternating light-and-dark bands, 8.5 nanometers thick.
For a long time, the three-dimensional structure of the thylakoid membrane system had been unknown or disputed. Many models have been proposed, the most prevalent being the helical model, in which granum stacks of thylakoids are wrapped by helical stromal thylakoids. Another model known as the 'bifurcation model', which was based on the first electron tomography study of plant thylakoid membranes, depicts the stromal membranes as wide lamellar sheets perpendicular to the grana columns which bifurcates into multiple parallel discs forming the granum-stroma assembly. The helical model was supported by several additional works, but ultimately it was determined in 2019 that features from both the helical and bifurcation models are consolidated by newly discovered left-handed helical membrane junctions. Likely for ease, the thylakoid system is still commonly depicted by older "hub and spoke" models where the grana are connected to each other by tubes of stromal thylakoids.
Grana consist of a stacks of flattened circular granal thylakoids that resemble pancakes. Each granum can contain anywhere from two to a hundred thylakoids, though grana with 10–20 thylakoids are most common. Wrapped around the grana are multiple parallel right-handed helical stromal thylakoids, also known as frets or lamellar thylakoids. The helices ascend at an angle of ~20°, connecting to each granal thylakoid at a bridge-like slit junction.
The stroma lamellae extend as large sheets perpendicular to the grana columns. These sheets are connected to the right-handed helices either directly or through bifurcations that form left-handed helical membrane surfaces. The left-handed helical surfaces have a similar tilt angle to the right-handed helices (~20°), but ¼ the pitch. Approximately 4 left-handed helical junctions are present per granum, resulting in a pitch-balanced array of right- and left-handed helical membrane surfaces of different radii and pitch that consolidate the network with minimal surface and bending energies. While different parts of the thylakoid system contain different membrane proteins, the thylakoid membranes are continuous and the thylakoid space they enclose form a single continuous labyrinth.
Embedded in the thylakoid membranes are important protein complexes which carry out the light reactions of photosynthesis. Photosystem II and photosystem I contain light-harvesting complexes with chlorophyll and carotenoids that absorb light energy and use it to energize electrons. Molecules in the thylakoid membrane use the energized electrons to pump hydrogen ions into the thylakoid space, decreasing the pH and turning it acidic. ATP synthase is a large protein complex that harnesses the concentration gradient of the hydrogen ions in the thylakoid space to generate ATP energy as the hydrogen ions flow back out into the stroma—much like a dam turbine.
There are two types of thylakoids—granal thylakoids, which are arranged in grana, and stromal thylakoids, which are in contact with the stroma. Granal thylakoids are pancake-shaped circular disks about 300–600 nanometers in diameter. Stromal thylakoids are helicoid sheets that spiral around grana. The flat tops and bottoms of granal thylakoids contain only the relatively flat photosystem II protein complex. This allows them to stack tightly, forming grana with many layers of tightly appressed membrane, called granal membrane, increasing stability and surface area for light capture.
In contrast, photosystem I and ATP synthase are large protein complexes which jut out into the stroma. They can't fit in the appressed granal membranes, and so are found in the stromal thylakoid membrane—the edges of the granal thylakoid disks and the stromal thylakoids. These large protein complexes may act as spacers between the sheets of stromal thylakoids.
The number of thylakoids and the total thylakoid area of a chloroplast is influenced by light exposure. Shaded chloroplasts contain larger and more grana with more thylakoid membrane area than chloroplasts exposed to bright light, which have smaller and fewer grana and less thylakoid area. Thylakoid extent can change within minutes of light exposure or removal.
Inside the photosystems embedded in chloroplast thylakoid membranes are various photosynthetic pigments, which absorb and transfer light energy. The types of pigments found are different in various groups of chloroplasts, and are responsible for a wide variety of chloroplast colorations.
Chlorophyll a is found in all chloroplasts, as well as their cyanobacterial ancestors. Chlorophyll a is a blue-green pigment partially responsible for giving most cyanobacteria and chloroplasts their color. Other forms of chlorophyll exist, such as the accessory pigments chlorophyll b, chlorophyll c, chlorophyll d, and chlorophyll f.
Chlorophyll b is an olive green pigment found only in the chloroplasts of plants, green algae, any secondary chloroplasts obtained through the secondary endosymbiosis of a green alga, and a few cyanobacteria. It is the chlorophylls a and b together that make most plant and green algal chloroplasts green.
Chlorophyll c is mainly found in secondary endosymbiotic chloroplasts that originated from a red alga, although it is not found in chloroplasts of red algae themselves. Chlorophyll c is also found in some green algae and cyanobacteria.
Chlorophylls d and f are pigments found only in some cyanobacteria.
In addition to chlorophylls, another group of yellow–orange pigments called carotenoids are also found in the photosystems. There are about thirty photosynthetic carotenoids. They help transfer and dissipate excess energy, and their bright colors sometimes override the chlorophyll green, like during the fall, when the leaves of some land plants change color. β-carotene is a bright red-orange carotenoid found in nearly all chloroplasts, like chlorophyll a. Xanthophylls, especially the orange-red zeaxanthin, are also common. Many other forms of carotenoids exist that are only found in certain groups of chloroplasts.
Phycobilins are a third group of pigments found in cyanobacteria, and glaucophyte, red algal, and cryptophyte chloroplasts. Phycobilins come in all colors, though phycoerytherin is one of the pigments that makes many red algae red. Phycobilins often organize into relatively large protein complexes about 40 nanometers across called phycobilisomes. Like photosystem I and ATP synthase, phycobilisomes jut into the stroma, preventing thylakoid stacking in red algal chloroplasts. Cryptophyte chloroplasts and some cyanobacteria don't have their phycobilin pigments organized into phycobilisomes, and keep them in their thylakoid space instead.
To fix carbon dioxide into sugar molecules in the process of photosynthesis, chloroplasts use an enzyme called RuBisCO. RuBisCO has trouble distinguishing between carbon dioxide and oxygen, so at high oxygen concentrations, RuBisCO starts accidentally adding oxygen to sugar precursors. This has the result of ATP energy being wasted and CO2 being released, all with no sugar being produced. This is a big problem, since O2 is produced by the initial light reactions of photosynthesis, causing issues down the line in the Calvin cycle which uses RuBisCO.
C4 plants evolved a way to solve this—by spatially separating the light reactions and the Calvin cycle. The light reactions, which store light energy in ATP and NADPH, are done in the mesophyll cells of a C4 leaf. The Calvin cycle, which uses the stored energy to make sugar using RuBisCO, is done in the bundle sheath cells, a layer of cells surrounding a vein in a leaf.
As a result, chloroplasts in C4 mesophyll cells and bundle sheath cells are specialized for each stage of photosynthesis. In mesophyll cells, chloroplasts are specialized for the light reactions, so they lack RuBisCO, and have normal grana and thylakoids, which they use to make ATP and NADPH, as well as oxygen. They store CO2 in a four-carbon compound, which is why the process is called C4 photosynthesis. The four-carbon compound is then transported to the bundle sheath chloroplasts, where it drops off CO2 and returns to the mesophyll. Bundle sheath chloroplasts do not carry out the light reactions, preventing oxygen from building up in them and disrupting RuBisCO activity. Because of this, they lack thylakoids organized into grana stacks—though bundle sheath chloroplasts still have free-floating thylakoids in the stroma where they still carry out cyclic electron flow, a light-driven method of synthesizing ATP to power the Calvin cycle without generating oxygen. They lack photosystem II, and only have photosystem I—the only protein complex needed for cyclic electron flow. Because the job of bundle sheath chloroplasts is to carry out the Calvin cycle and make sugar, they often contain large starch grains.
Both types of chloroplast contain large amounts of chloroplast peripheral reticulum, which they use to get more surface area to transport stuff in and out of them. Mesophyll chloroplasts have a little more peripheral reticulum than bundle sheath chloroplasts.
Not all cells in a multicellular plant contain chloroplasts. All green parts of a plant contain chloroplasts—the chloroplasts, or more specifically, the chlorophyll in them are what make the photosynthetic parts of a plant green. The plant cells which contain chloroplasts are usually parenchyma cells, though chloroplasts can also be found in collenchyma tissue. A plant cell which contains chloroplasts is known as a chlorenchyma cell. A typical chlorenchyma cell of a land plant contains about 10 to 100 chloroplasts.
In some plants such as cacti, chloroplasts are found in the stems, though in most plants, chloroplasts are concentrated in the leaves. One square millimeter of leaf tissue can contain half a million chloroplasts. Within a leaf, chloroplasts are mainly found in the mesophyll layers of a leaf, and the guard cells of stomata. Palisade mesophyll cells can contain 30–70 chloroplasts per cell, while stomatal guard cells contain only around 8–15 per cell, as well as much less chlorophyll. Chloroplasts can also be found in the bundle sheath cells of a leaf, especially in C4 plants, which carry out the Calvin cycle in their bundle sheath cells. They are often absent from the epidermis of a leaf.
The chloroplasts of plant and algal cells can orient themselves to best suit the available light. In low-light conditions, they will spread out in a sheet—maximizing the surface area to absorb light. Under intense light, they will seek shelter by aligning in vertical columns along the plant cell's cell wall or turning sideways so that light strikes them edge-on. This reduces exposure and protects them from photooxidative damage. This ability to distribute chloroplasts so that they can take shelter behind each other or spread out may be the reason why land plants evolved to have many small chloroplasts instead of a few big ones. Chloroplast movement is considered one of the most closely regulated stimulus-response systems that can be found in plants. Mitochondria have also been observed to follow chloroplasts as they move.
In higher plants, chloroplast movement is run by phototropins, blue light photoreceptors also responsible for plant phototropism. In some algae, mosses, ferns, and flowering plants, chloroplast movement is influenced by red light in addition to blue light, though very long red wavelengths inhibit movement rather than speeding it up. Blue light generally causes chloroplasts to seek shelter, while red light draws them out to maximize light absorption.
Studies of Vallisneria gigantea, an aquatic flowering plant, have shown that chloroplasts can get moving within five minutes of light exposure, though they don't initially show any net directionality. They may move along microfilament tracks, and the fact that the microfilament mesh changes shape to form a honeycomb structure surrounding the chloroplasts after they have moved suggests that microfilaments may help to anchor chloroplasts in place.
Unlike most epidermal cells, the guard cells of plant stomata contain relatively well-developed chloroplasts. However, exactly what they do is controversial.
Plants lack specialized immune cells—all plant cells participate in the plant immune response. Chloroplasts, along with the nucleus, cell membrane, and endoplasmic reticulum, are key players in pathogen defense. Due to its role in a plant cell's immune response, pathogens frequently target the chloroplast.
Plants have two main immune responses—the hypersensitive response, in which infected cells seal themselves off and undergo programmed cell death, and systemic acquired resistance, where infected cells release signals warning the rest of the plant of a pathogen's presence. Chloroplasts stimulate both responses by purposely damaging their photosynthetic system, producing reactive oxygen species. High levels of reactive oxygen species will cause the hypersensitive response. The reactive oxygen species also directly kill any pathogens within the cell. Lower levels of reactive oxygen species initiate systemic acquired resistance, triggering defense-molecule production in the rest of the plant.
In some plants, chloroplasts are known to move closer to the infection site and the nucleus during an infection.
Chloroplasts can serve as cellular sensors. After detecting stress in a cell, which might be due to a pathogen, chloroplasts begin producing molecules like salicylic acid, jasmonic acid, nitric oxide and reactive oxygen species which can serve as defense-signals. As cellular signals, reactive oxygen species are unstable molecules, so they probably don't leave the chloroplast, but instead pass on their signal to an unknown second messenger molecule. All these molecules initiate retrograde signaling—signals from the chloroplast that regulate gene expression in the nucleus.
In addition to defense signaling, chloroplasts, with the help of the peroxisomes, help synthesize an important defense molecule, jasmonate. Chloroplasts synthesize all the fatty acids in a plant cell—linoleic acid, a fatty acid, is a precursor to jasmonate.
One of the main functions of the chloroplast is its role in photosynthesis, the process by which light is transformed into chemical energy, to subsequently produce food in the form of sugars. Water (H2O) and carbon dioxide (CO2) are used in photosynthesis, and sugar and oxygen (O2) is made, using light energy. Photosynthesis is divided into two stages—the light reactions, where water is split to produce oxygen, and the dark reactions, or Calvin cycle, which builds sugar molecules from carbon dioxide. The two phases are linked by the energy carriers adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADP).
The light reactions take place on the thylakoid membranes. They take light energy and store it in NADPH, a form of NADP, and ATP to fuel the dark reactions.
ATP is the phosphorylated version of adenosine diphosphate (ADP), which stores energy in a cell and powers most cellular activities. ATP is the energized form, while ADP is the (partially) depleted form. NADP is an electron carrier which ferries high energy electrons. In the light reactions, it gets reduced, meaning it picks up electrons, becoming NADPH.
Like mitochondria, chloroplasts use the potential energy stored in an H, or hydrogen ion, gradient to generate ATP energy. The two photosystems capture light energy to energize electrons taken from water, and release them down an electron transport chain. The molecules between the photosystems harness the electrons' energy to pump hydrogen ions into the thylakoid space, creating a concentration gradient, with more hydrogen ions (up to a thousand times as many) inside the thylakoid system than in the stroma. The hydrogen ions in the thylakoid space then diffuse back down their concentration gradient, flowing back out into the stroma through ATP synthase. ATP synthase uses the energy from the flowing hydrogen ions to phosphorylate adenosine diphosphate into adenosine triphosphate, or ATP. Because chloroplast ATP synthase projects out into the stroma, the ATP is synthesized there, in position to be used in the dark reactions.
Electrons are often removed from the electron transport chains to charge NADP with electrons, reducing it to NADPH. Like ATP synthase, ferredoxin-NADP reductase, the enzyme that reduces NADP, releases the NADPH it makes into the stroma, right where it is needed for the dark reactions.
Because NADP reduction removes electrons from the electron transport chains, they must be replaced—the job of photosystem II, which splits water molecules (H2O) to obtain the electrons from its hydrogen atoms.
While photosystem II photolyzes water to obtain and energize new electrons, photosystem I simply reenergizes depleted electrons at the end of an electron transport chain. Normally, the reenergized electrons are taken by NADP, though sometimes they can flow back down more H-pumping electron transport chains to transport more hydrogen ions into the thylakoid space to generate more ATP. This is termed cyclic photophosphorylation because the electrons are recycled. Cyclic photophosphorylation is common in C4 plants, which need more ATP than NADPH.
The Calvin cycle, also known as the dark reactions, is a series of biochemical reactions that fixes CO2 into G3P sugar molecules and uses the energy and electrons from the ATP and NADPH made in the light reactions. The Calvin cycle takes place in the stroma of the chloroplast.
While named "the dark reactions", in most plants, they take place in the light, since the dark reactions are dependent on the products of the light reactions.
The Calvin cycle starts by using the enzyme RuBisCO to fix CO2 into five-carbon Ribulose bisphosphate (RuBP) molecules. The result is unstable six-carbon molecules that immediately break down into three-carbon molecules called 3-phosphoglyceric acid, or 3-PGA. The ATP and NADPH made in the light reactions is used to convert the 3-PGA into glyceraldehyde-3-phosphate, or G3P sugar molecules. Most of the G3P molecules are recycled back into RuBP using energy from more ATP, but one out of every six produced leaves the cycle—the end product of the dark reactions.
Glyceraldehyde-3-phosphate can double up to form larger sugar molecules like glucose and fructose. These molecules are processed, and from them, the still larger sucrose, a disaccharide commonly known as table sugar, is made, though this process takes place outside of the chloroplast, in the cytoplasm.
Alternatively, glucose monomers in the chloroplast can be linked together to make starch, which accumulates into the starch grains found in the chloroplast. Under conditions such as high atmospheric CO2 concentrations, these starch grains may grow very large, distorting the grana and thylakoids. The starch granules displace the thylakoids, but leave them intact. Waterlogged roots can also cause starch buildup in the chloroplasts, possibly due to less sucrose being exported out of the chloroplast (or more accurately, the plant cell). This depletes a plant's free phosphate supply, which indirectly stimulates chloroplast starch synthesis. While linked to low photosynthesis rates, the starch grains themselves may not necessarily interfere significantly with the efficiency of photosynthesis, and might simply be a side effect of another photosynthesis-depressing factor.
Photorespiration can occur when the oxygen concentration is too high. RuBisCO cannot distinguish between oxygen and carbon dioxide very well, so it can accidentally add O2 instead of CO2 to RuBP. This process reduces the efficiency of photosynthesis—it consumes ATP and oxygen, releases CO2, and produces no sugar. It can waste up to half the carbon fixed by the Calvin cycle. Several mechanisms have evolved in different lineages that raise the carbon dioxide concentration relative to oxygen within the chloroplast, increasing the efficiency of photosynthesis. These mechanisms are called carbon dioxide concentrating mechanisms, or CCMs. These include Crassulacean acid metabolism, C4 carbon fixation, and pyrenoids. Chloroplasts in C4 plants are notable as they exhibit a distinct chloroplast dimorphism.
Because of the H gradient across the thylakoid membrane, the interior of the thylakoid is acidic, with a pH around 4, while the stroma is slightly basic, with a pH of around 8. The optimal stroma pH for the Calvin cycle is 8.1, with the reaction nearly stopping when the pH falls below 7.3.
CO2 in water can form carbonic acid, which can disturb the pH of isolated chloroplasts, interfering with photosynthesis, even though CO2 is used in photosynthesis. However, chloroplasts in living plant cells are not affected by this as much.
Chloroplasts can pump K and H ions in and out of themselves using a poorly understood light-driven transport system.
In the presence of light, the pH of the thylakoid lumen can drop up to 1.5 pH units, while the pH of the stroma can rise by nearly one pH unit.
Chloroplasts alone make almost all of a plant cell's amino acids in their stroma except the sulfur-containing ones like cysteine and methionine. Cysteine is made in the chloroplast (the proplastid too) but it is also synthesized in the cytosol and mitochondria, probably because it has trouble crossing membranes to get to where it is needed. The chloroplast is known to make the precursors to methionine but it is unclear whether the organelle carries out the last leg of the pathway or if it happens in the cytosol.
Chloroplasts make all of a cell's purines and pyrimidines—the nitrogenous bases found in DNA and RNA. They also convert nitrite (NO2) into ammonia (NH3) which supplies the plant with nitrogen to make its amino acids and nucleotides.
The plastid is the site of diverse and complex lipid synthesis in plants. The carbon used to form the majority of the lipid is from acetyl-CoA, which is the decarboxylation product of pyruvate. Pyruvate may enter the plastid from the cytosol by passive diffusion through the membrane after production in glycolysis. Pyruvate is also made in the plastid from phosphoenolpyruvate, a metabolite made in the cytosol from pyruvate or PGA. Acetate in the cytosol is unavailable for lipid biosynthesis in the plastid. The typical length of fatty acids produced in the plastid are 16 or 18 carbons, with 0-3 cis double bonds.
The biosynthesis of fatty acids from acetyl-CoA primarily requires two enzymes. Acetyl-CoA carboxylase creates malonyl-CoA, used in both the first step and the extension steps of synthesis. Fatty acid synthase (FAS) is a large complex of enzymes and cofactors including acyl carrier protein (ACP) which holds the acyl chain as it is synthesized. The initiation of synthesis begins with the condensation of malonyl-ACP with acetyl-CoA to produce ketobutyryl-ACP. 2 reductions involving the use of NADPH and one dehydration creates butyryl-ACP. Extension of the fatty acid comes from repeated cycles of malonyl-ACP condensation, reduction, and dehydration.
Other lipids are derived from the methyl-erythritol phosphate (MEP) pathway and consist of gibberelins, sterols, abscisic acid, phytol, and innumerable secondary metabolites.
Chloroplasts are a special type of a plant cell organelle called a plastid, though the two terms are sometimes used interchangeably. There are many other types of plastids, which carry out various functions. All chloroplasts in a plant are descended from undifferentiated proplastids found in the zygote, or fertilized egg. Proplastids are commonly found in an adult plant's apical meristems. Chloroplasts do not normally develop from proplastids in root tip meristems—instead, the formation of starch-storing amyloplasts is more common.
In shoots, proplastids from shoot apical meristems can gradually develop into chloroplasts in photosynthetic leaf tissues as the leaf matures, if exposed to the required light. This process involves invaginations of the inner plastid membrane, forming sheets of membrane that project into the internal stroma. These membrane sheets then fold to form thylakoids and grana.
If angiosperm shoots are not exposed to the required light for chloroplast formation, proplastids may develop into an etioplast stage before becoming chloroplasts. An etioplast is a plastid that lacks chlorophyll, and has inner membrane invaginations that form a lattice of tubes in their stroma, called a prolamellar body. While etioplasts lack chlorophyll, they have a yellow chlorophyll precursor stocked. Within a few minutes of light exposure, the prolamellar body begins to reorganize into stacks of thylakoids, and chlorophyll starts to be produced. This process, where the etioplast becomes a chloroplast, takes several hours. Gymnosperms do not require light to form chloroplasts.
Light, however, does not guarantee that a proplastid will develop into a chloroplast. Whether a proplastid develops into a chloroplast some other kind of plastid is mostly controlled by the nucleus and is largely influenced by the kind of cell it resides in.
Plastid differentiation is not permanent, in fact many interconversions are possible. Chloroplasts may be converted to chromoplasts, which are pigment-filled plastids responsible for the bright colors seen in flowers and ripe fruit. Starch storing amyloplasts can also be converted to chromoplasts, and it is possible for proplastids to develop straight into chromoplasts. Chromoplasts and amyloplasts can also become chloroplasts, like what happens when a carrot or a potato is illuminated. If a plant is injured, or something else causes a plant cell to revert to a meristematic state, chloroplasts and other plastids can turn back into proplastids. Chloroplast, amyloplast, chromoplast, proplastid are not absolute; state—intermediate forms are common.
Most chloroplasts in a photosynthetic cell do not develop directly from proplastids or etioplasts. In fact, a typical shoot meristematic plant cell contains only 7–20 proplastids. These proplastids differentiate into chloroplasts, which divide to create the 30–70 chloroplasts found in a mature photosynthetic plant cell. If the cell divides, chloroplast division provides the additional chloroplasts to partition between the two daughter cells.
In single-celled algae, chloroplast division is the only way new chloroplasts are formed. There is no proplastid differentiation—when an algal cell divides, its chloroplast divides along with it, and each daughter cell receives a mature chloroplast.
Almost all chloroplasts in a cell divide, rather than a small group of rapidly dividing chloroplasts. Chloroplasts have no definite S-phase—their DNA replication is not synchronized or limited to that of their host cells. Much of what we know about chloroplast division comes from studying organisms like Arabidopsis and the red alga Cyanidioschyzon merolæ.
The division process starts when the proteins FtsZ1 and FtsZ2 assemble into filaments, and with the help of a protein ARC6, form a structure called a Z-ring within the chloroplast's stroma. The Min system manages the placement of the Z-ring, ensuring that the chloroplast is cleaved more or less evenly. The protein MinD prevents FtsZ from linking up and forming filaments. Another protein ARC3 may also be involved, but it is not very well understood. These proteins are active at the poles of the chloroplast, preventing Z-ring formation there, but near the center of the chloroplast, MinE inhibits them, allowing the Z-ring to form.
Next, the two plastid-dividing rings, or PD rings form. The inner plastid-dividing ring is located in the inner side of the chloroplast's inner membrane, and is formed first. The outer plastid-dividing ring is found wrapped around the outer chloroplast membrane. It consists of filaments about 5 nanometers across, arranged in rows 6.4 nanometers apart, and shrinks to squeeze the chloroplast. This is when chloroplast constriction begins. In a few species like Cyanidioschyzon merolæ, chloroplasts have a third plastid-dividing ring located in the chloroplast's intermembrane space.
Late into the constriction phase, dynamin proteins assemble around the outer plastid-dividing ring, helping provide force to squeeze the chloroplast. Meanwhile, the Z-ring and the inner plastid-dividing ring break down. During this stage, the many chloroplast DNA plasmids floating around in the stroma are partitioned and distributed to the two forming daughter chloroplasts.
Later, the dynamins migrate under the outer plastid dividing ring, into direct contact with the chloroplast's outer membrane, to cleave the chloroplast in two daughter chloroplasts.
A remnant of the outer plastid dividing ring remains floating between the two daughter chloroplasts, and a remnant of the dynamin ring remains attached to one of the daughter chloroplasts.
Of the five or six rings involved in chloroplast division, only the outer plastid-dividing ring is present for the entire constriction and division phase—while the Z-ring forms first, constriction does not begin until the outer plastid-dividing ring forms.
In species of algae that contain a single chloroplast, regulation of chloroplast division is extremely important to ensure that each daughter cell receives a chloroplast—chloroplasts can't be made from scratch. In organisms like plants, whose cells contain multiple chloroplasts, coordination is looser and less important. It is likely that chloroplast and cell division are somewhat synchronized, though the mechanisms for it are mostly unknown.
Light has been shown to be a requirement for chloroplast division. Chloroplasts can grow and progress through some of the constriction stages under poor quality green light, but are slow to complete division—they require exposure to bright white light to complete division. Spinach leaves grown under green light have been observed to contain many large dumbbell-shaped chloroplasts. Exposure to white light can stimulate these chloroplasts to divide and reduce the population of dumbbell-shaped chloroplasts.
Like mitochondria, chloroplasts are usually inherited from a single parent. Biparental chloroplast inheritance—where plastid genes are inherited from both parent plants—occurs in very low levels in some flowering plants.
Many mechanisms prevent biparental chloroplast DNA inheritance, including selective destruction of chloroplasts or their genes within the gamete or zygote, and chloroplasts from one parent being excluded from the embryo. Parental chloroplasts can be sorted so that only one type is present in each offspring.
Gymnosperms, such as pine trees, mostly pass on chloroplasts paternally, while flowering plants often inherit chloroplasts maternally. Flowering plants were once thought to only inherit chloroplasts maternally. However, there are now many documented cases of angiosperms inheriting chloroplasts paternally.
Angiosperms, which pass on chloroplasts maternally, have many ways to prevent paternal inheritance. Most of them produce sperm cells that do not contain any plastids. There are many other documented mechanisms that prevent paternal inheritance in these flowering plants, such as different rates of chloroplast replication within the embryo.
Among angiosperms, paternal chloroplast inheritance is observed more often in hybrids than in offspring from parents of the same species. This suggests that incompatible hybrid genes might interfere with the mechanisms that prevent paternal inheritance.
Recently, chloroplasts have caught attention by developers of genetically modified crops. Since, in most flowering plants, chloroplasts are not inherited from the male parent, transgenes in these plastids cannot be disseminated by pollen. This makes plastid transformation a valuable tool for the creation and cultivation of genetically modified plants that are biologically contained, thus posing significantly lower environmental risks. This biological containment strategy is therefore suitable for establishing the coexistence of conventional and organic agriculture. While the reliability of this mechanism has not yet been studied for all relevant crop species, recent results in tobacco plants are promising, showing a failed containment rate of transplastomic plants at 3 in 1,000,000. | [
{
"paragraph_id": 0,
"text": "A chloroplast (/ˈklɔːrəˌplæst, -plɑːst/) is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water in the cells. The ATP and NADPH is then used to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from one, in unicellular algae, up to 100 in plants like Arabidopsis and wheat.",
"title": ""
},
{
"paragraph_id": 1,
"text": "A chloroplast is characterized by its two membranes and a high concentration of chlorophyll. Other plastid types, such as the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photosynthesis.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Chloroplasts are highly dynamic—they circulate and are moved around within plant cells, and occasionally pinch in two to reproduce. Their behavior is strongly influenced by environmental factors like light color and intensity. Chloroplasts, like mitochondria, contain their own DNA, which is thought to be inherited from their ancestor—a photosynthetic cyanobacterium that was engulfed by an early eukaryotic cell. Chloroplasts cannot be made by the plant cell and must be inherited by each daughter cell during cell division.",
"title": ""
},
{
"paragraph_id": 3,
"text": "With one exception (the amoeboid Paulinella chromatophora), all chloroplasts can probably be traced back to a single endosymbiotic event, when a cyanobacterium was engulfed by the eukaryote. Despite this, chloroplasts can be found in an extremely wide set of organisms, some not even directly related to each other—a consequence of many secondary and even tertiary endosymbiotic events.",
"title": ""
},
{
"paragraph_id": 4,
"text": "The word chloroplast is derived from the Greek words chloros (χλωρός), which means green, and plastes (πλάστης), which means \"the one who forms\".",
"title": ""
},
{
"paragraph_id": 5,
"text": "The first definitive description of a chloroplast (Chlorophyllkörnen, \"grain of chlorophyll\") was given by Hugo von Mohl in 1837 as discrete bodies within the green plant cell. In 1883, Andreas Franz Wilhelm Schimper would name these bodies as \"chloroplastids\" (Chloroplastiden). In 1884, Eduard Strasburger adopted the term \"chloroplasts\" (Chloroplasten).",
"title": "Discovery"
},
{
"paragraph_id": 6,
"text": "Chloroplasts are one of many types of organelles in the plant cell. They are considered to have evolved from endosymbiotic cyanobacteria. Mitochondria are thought to have come from a similar endosymbiosis event, where an aerobic prokaryote was engulfed. This origin of chloroplasts was first suggested by the Russian biologist Konstantin Mereschkowski in 1905 after Andreas Franz Wilhelm Schimper observed in 1883 that chloroplasts closely resemble cyanobacteria. Chloroplasts are only found in plants, algae, and three species of amoeba – Paulinella chromatophora, P. micropora, and marine P. longichromatophora.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 7,
"text": "Chloroplasts are considered endosymbiotic Cyanobacteria. Cyanobacteria are sometimes called blue-green algae even though they are prokaryotes. They are a diverse phylum of gram-negative bacteria capable of carrying out photosynthesis. Cyanobacteria also contain a peptidoglycan cell wall, which is thicker than in other gram-negative bacteria, and which is located between their two cell membranes. Like chloroplasts, they have thylakoids within them. On the thylakoid membranes are photosynthetic pigments, including chlorophyll a. Phycobilins are also common cyanobacterial pigments, usually organized into hemispherical phycobilisomes attached to the outside of the thylakoid membranes (phycobilins are not shared with all chloroplasts though).",
"title": "Lineages and evolution"
},
{
"paragraph_id": 8,
"text": "Somewhere between 1 and 2 billion years ago, a free-living cyanobacterium entered an early eukaryotic cell, either as food or as an internal parasite, but managed to escape the phagocytic vacuole it was contained in. The two innermost lipid-bilayer membranes that surround all chloroplasts correspond to the outer and inner membranes of the ancestral cyanobacterium's gram negative cell wall, and not the phagosomal membrane from the host, which was probably lost. The new cellular resident quickly became an advantage, providing food for the eukaryotic host, which allowed it to live within it. Over time, the cyanobacterium was assimilated, and many of its genes were lost or transferred to the nucleus of the host. From genomes that probably originally contained over 3000 genes only about 130 genes remain in the chloroplasts of contemporary plants. Some of its proteins were then synthesized in the cytoplasm of the host cell, and imported back into the chloroplast (formerly the cyanobacterium). Separately, somewhere about 90–140 million years ago, it happened again and led to the amoeboid Paulinella chromatophora.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 9,
"text": "This event is called endosymbiosis, or \"cell living inside another cell with a mutual benefit for both\". The external cell is commonly referred to as the host while the internal cell is called the endosymbiont.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 10,
"text": "Chloroplasts are believed to have arisen after mitochondria, since all eukaryotes contain mitochondria, but not all have chloroplasts. This is called serial endosymbiosis—an early eukaryote engulfing the mitochondrion ancestor, and some descendants of it then engulfing the chloroplast ancestor, creating a cell with both chloroplasts and mitochondria.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 11,
"text": "Whether or not primary chloroplasts came from a single endosymbiotic event, or many independent engulfments across various eukaryotic lineages, has long been debated. It is now generally held that organisms with primary chloroplasts share a single ancestor that took in a cyanobacterium 600–2000 million years ago. It has been proposed this the closest living relative of this bacterium is Gloeomargarita lithophora. The exception is the amoeboid Paulinella chromatophora, which descends from an ancestor that took in a Prochlorococcus cyanobacterium 90–500 million years ago.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 12,
"text": "These chloroplasts, which can be traced back directly to a cyanobacterial ancestor, are known as primary plastids (\"plastid\" in this context means almost the same thing as chloroplast). All primary chloroplasts belong to one of four chloroplast lineages—the glaucophyte chloroplast lineage, the amoeboid Paulinella chromatophora lineage, the rhodophyte (red algal) chloroplast lineage, or the chloroplastidan (green) chloroplast lineage. The rhodophyte and chloroplastidan lineages are the largest, with chloroplastidan (green) being the one that contains the land plants.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 13,
"text": "Usually the endosymbiosis event is considered to have occurred in the Archaeplastida, within which the glaucophyta being the possible earliest diverging lineage. The glaucophyte chloroplast group is the smallest of the three primary chloroplast lineages, being found in only 13 species, and is thought to be the one that branched off the earliest. Glaucophytes have chloroplasts that retain a peptidoglycan wall between their double membranes, like their cyanobacterial parent. For this reason, glaucophyte chloroplasts are also known as 'muroplasts' (besides 'cyanoplasts' or 'cyanelles'). Glaucophyte chloroplasts also contain concentric unstacked thylakoids, which surround a carboxysome – an icosahedral structure that glaucophyte chloroplasts and cyanobacteria keep their carbon fixation enzyme RuBisCO in. The starch that they synthesize collects outside the chloroplast. Like cyanobacteria, glaucophyte and rhodophyte chloroplast thylakoids are studded with light collecting structures called phycobilisomes. For these reasons, glaucophyte chloroplasts are considered a primitive intermediate between cyanobacteria and the more evolved chloroplasts in red algae and plants.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 14,
"text": "The rhodophyte, or red algae chloroplast group is another large and diverse chloroplast lineage. Rhodophyte chloroplasts are also called rhodoplasts, literally \"red chloroplasts\".",
"title": "Lineages and evolution"
},
{
"paragraph_id": 15,
"text": "Rhodoplasts have a double membrane with an intermembrane space and phycobilin pigments organized into phycobilisomes on the thylakoid membranes, preventing their thylakoids from stacking. Some contain pyrenoids. Rhodoplasts have chlorophyll a and phycobilins for photosynthetic pigments; the phycobilin phycoerythrin is responsible for giving many red algae their distinctive red color. However, since they also contain the blue-green chlorophyll a and other pigments, many are reddish to purple from the combination. The red phycoerytherin pigment is an adaptation to help red algae catch more sunlight in deep water—as such, some red algae that live in shallow water have less phycoerythrin in their rhodoplasts, and can appear more greenish. Rhodoplasts synthesize a form of starch called floridean starch, which collects into granules outside the rhodoplast, in the cytoplasm of the red alga.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 16,
"text": "The chloroplastida chloroplasts, or green chloroplasts, are another large, highly diverse primary chloroplast lineage. Their host organisms are commonly known as green algae and land plants. They differ from glaucophyte and red algal chloroplasts in that they have lost their phycobilisomes, and contain chlorophyll b instead. Most green chloroplasts are (obviously) green, though some aren't, like some forms of Hæmatococcus pluvialis, due to accessory pigments that override the chlorophylls' green colors. Chloroplastida chloroplasts have lost the peptidoglycan wall between their double membrane, leaving an intermembrane space. Some plants seem to have kept the genes for the synthesis of the peptidoglycan layer, though they've been repurposed for use in chloroplast division instead.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 17,
"text": "Most of the chloroplasts depicted in this article are green chloroplasts.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 18,
"text": "Green algae and plants keep their starch inside their chloroplasts, and in plants and some algae, the chloroplast thylakoids are arranged in grana stacks. Some green algal chloroplasts contain a structure called a pyrenoid, which is functionally similar to the glaucophyte carboxysome in that it is where RuBisCO and CO2 are concentrated in the chloroplast.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 19,
"text": "Helicosporidium is a genus of nonphotosynthetic parasitic green algae that is thought to contain a vestigial chloroplast. Genes from a chloroplast and nuclear genes indicating the presence of a chloroplast have been found in Helicosporidium even if nobody's seen the chloroplast itself.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 20,
"text": "While most chloroplasts originate from that first set of endosymbiotic events, Paulinella chromatophora is an exception that acquired a photosynthetic cyanobacterial endosymbiont more recently. It is not clear whether that symbiont is closely related to the ancestral chloroplast of other eukaryotes. Being in the early stages of endosymbiosis, Paulinella chromatophora can offer some insights into how chloroplasts evolved. Paulinella cells contain one or two sausage-shaped blue-green photosynthesizing structures called chromatophores, descended from the cyanobacterium Synechococcus. Chromatophores cannot survive outside their host. Chromatophore DNA is about a million base pairs long, containing around 850 protein-encoding genes—far less than the three million base pair Synechococcus genome, but much larger than the approximately 150,000 base pair genome of the more assimilated chloroplast. Chromatophores have transferred much less of their DNA to the nucleus of their host. About 0.3–0.8% of the nuclear DNA in Paulinella is from the chromatophore, compared with 11–14% from the chloroplast in plants.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 21,
"text": "",
"title": "Lineages and evolution"
},
{
"paragraph_id": 22,
"text": "",
"title": "Lineages and evolution"
},
{
"paragraph_id": 23,
"text": "",
"title": "Lineages and evolution"
},
{
"paragraph_id": 24,
"text": "It is now established that Chromalveolata is paraphyletic to Rhizaria.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 25,
"text": "Edit",
"title": "Lineages and evolution"
},
{
"paragraph_id": 26,
"text": "Many other organisms obtained chloroplasts from the primary chloroplast lineages through secondary endosymbiosis—engulfing a red or green alga that contained a chloroplast. These chloroplasts are known as secondary plastids.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 27,
"text": "While primary chloroplasts have a double membrane from their cyanobacterial ancestor, secondary chloroplasts have additional membranes outside of the original two, as a result of the secondary endosymbiotic event, when a nonphotosynthetic eukaryote engulfed a chloroplast-containing alga but failed to digest it—much like the cyanobacterium at the beginning of this story. The engulfed alga was broken down, leaving only its chloroplast, and sometimes its cell membrane and nucleus, forming a chloroplast with three or four membranes—the two cyanobacterial membranes, sometimes the eaten alga's cell membrane, and the phagosomal vacuole from the host's cell membrane.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 28,
"text": "The genes in the phagocytosed eukaryote's nucleus are often transferred to the secondary host's nucleus. Cryptomonads and chlorarachniophytes retain the phagocytosed eukaryote's nucleus, an object called a nucleomorph, located between the second and third membranes of the chloroplast.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 29,
"text": "All secondary chloroplasts come from green and red algae—no secondary chloroplasts from glaucophytes have been observed, probably because glaucophytes are relatively rare in nature, making them less likely to have been taken up by another eukaryote.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 30,
"text": "Green algae have been taken up by the euglenids, chlorarachniophytes, a lineage of dinoflagellates, and possibly the ancestor of the CASH lineage (cryptomonads, alveolates, stramenopiles and haptophytes) in three or four separate engulfments. Many green algal derived chloroplasts contain pyrenoids, but unlike chloroplasts in their green algal ancestors, storage product collects in granules outside the chloroplast.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 31,
"text": "Euglenophytes are a group of common flagellated protists that contain chloroplasts derived from a green alga. Euglenophyte chloroplasts have three membranes—it is thought that the membrane of the primary endosymbiont was lost, leaving the cyanobacterial membranes, and the secondary host's phagosomal membrane. Euglenophyte chloroplasts have a pyrenoid and thylakoids stacked in groups of three. Photosynthetic product is stored in the form of paramylon, which is contained in membrane-bound granules in the cytoplasm of the euglenophyte.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 32,
"text": "Chlorarachniophytes /ˌklɔːrəˈræknioʊˌfaɪts/ are a rare group of organisms that also contain chloroplasts derived from green algae, though their story is more complicated than that of the euglenophytes. The ancestor of chlorarachniophytes is thought to have been a eukaryote with a red algal derived chloroplast. It is then thought to have lost its first red algal chloroplast, and later engulfed a green alga, giving it its second, green algal derived chloroplast.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 33,
"text": "Chlorarachniophyte chloroplasts are bounded by four membranes, except near the cell membrane, where the chloroplast membranes fuse into a double membrane. Their thylakoids are arranged in loose stacks of three. Chlorarachniophytes have a form of polysaccharide called chrysolaminarin, which they store in the cytoplasm, often collected around the chloroplast pyrenoid, which bulges into the cytoplasm.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 34,
"text": "Chlorarachniophyte chloroplasts are notable because the green alga they are derived from has not been completely broken down—its nucleus still persists as a nucleomorph found between the second and third chloroplast membranes—the periplastid space, which corresponds to the green alga's cytoplasm.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 35,
"text": "Lepidodinium viride and its close relatives are dinophytes (see below) that lost their original peridinin chloroplast and replaced it with a green algal derived chloroplast (more specifically, a prasinophyte). Lepidodinium is the only dinophyte that has a chloroplast that's not from the rhodoplast lineage. The chloroplast is surrounded by two membranes and has no nucleomorph—all the nucleomorph genes have been transferred to the dinophyte nucleus. The endosymbiotic event that led to this chloroplast was serial secondary endosymbiosis rather than tertiary endosymbiosis—the endosymbiont was a green alga containing a primary chloroplast (making a secondary chloroplast).",
"title": "Lineages and evolution"
},
{
"paragraph_id": 36,
"text": "Cryptophytes, or cryptomonads are a group of algae that contain a red-algal derived chloroplast. Cryptophyte chloroplasts contain a nucleomorph that superficially resembles that of the chlorarachniophytes. Cryptophyte chloroplasts have four membranes, the outermost of which is continuous with the rough endoplasmic reticulum. They synthesize ordinary starch, which is stored in granules found in the periplastid space—outside the original double membrane, in the place that corresponds to the red alga's cytoplasm. Inside cryptophyte chloroplasts is a pyrenoid and thylakoids in stacks of two.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 37,
"text": "Their chloroplasts do not have phycobilisomes, but they do have phycobilin pigments which they keep in their thylakoid space, rather than anchored on the outside of their thylakoid membranes.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 38,
"text": "Cryptophytes may have played a key role in the spreading of red algal based chloroplasts.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 39,
"text": "Haptophytes are similar and closely related to cryptophytes or heterokontophytes. Their chloroplasts lack a nucleomorph, their thylakoids are in stacks of three, and they synthesize chrysolaminarin sugar, which they store completely outside of the chloroplast, in the cytoplasm of the haptophyte.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 40,
"text": "The heterokontophytes, also known as the stramenopiles, are a very large and diverse group of eukaryotes. The photoautotrophic lineage, Ochrophyta, including the diatoms and the brown algae, golden algae, and yellow-green algae, also contains red algal derived chloroplasts.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 41,
"text": "Heterokont chloroplasts are very similar to haptophyte chloroplasts, containing a pyrenoid, triplet thylakoids, and with some exceptions, having four layer plastidic envelope, the outermost epiplastid membrane connected to the endoplasmic reticulum. Like haptophytes, heterokontophytes store sugar in chrysolaminarin granules in the cytoplasm. Heterokontophyte chloroplasts contain chlorophyll a and with a few exceptions chlorophyll c, but also have carotenoids which give them their many colors.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 42,
"text": "The alveolates are a major clade of unicellular eukaryotes of both autotrophic and heterotrophic members. The most notable shared characteristic is the presence of cortical (outer-region) alveoli (sacs). These are flattened vesicles (sacs) packed into a continuous layer just under the membrane and supporting it, typically forming a flexible pellicle (thin skin). In dinoflagellates they often form armor plates. Many members contain a red-algal derived plastid. One notable characteristic of this diverse group is the frequent loss of photosynthesis. However, a majority of these heterotrophs continue to process a non-photosynthetic plastid.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 43,
"text": "Apicomplexans are a group of alveolates. Like the helicosproidia, they're parasitic, and have a nonphotosynthetic chloroplast. They were once thought to be related to the helicosproidia, but it is now known that the helicosproida are green algae rather than part of the CASH lineage. The apicomplexans include Plasmodium, the malaria parasite. Many apicomplexans keep a vestigial red algal derived chloroplast called an apicoplast, which they inherited from their ancestors. Other apicomplexans like Cryptosporidium have lost the chloroplast completely. Apicomplexans store their energy in amylopectin granules that are located in their cytoplasm, even though they are nonphotosynthetic.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 44,
"text": "Apicoplasts have lost all photosynthetic function, and contain no photosynthetic pigments or true thylakoids. They are bounded by four membranes, but the membranes are not connected to the endoplasmic reticulum. The fact that apicomplexans still keep their nonphotosynthetic chloroplast around demonstrates how the chloroplast carries out important functions other than photosynthesis. Plant chloroplasts provide plant cells with many important things besides sugar, and apicoplasts are no different—they synthesize fatty acids, isopentenyl pyrophosphate, iron-sulfur clusters, and carry out part of the heme pathway. This makes the apicoplast an attractive target for drugs to cure apicomplexan-related diseases. The most important apicoplast function is isopentenyl pyrophosphate synthesis—in fact, apicomplexans die when something interferes with this apicoplast function, and when apicomplexans are grown in an isopentenyl pyrophosphate-rich medium, they dump the organelle.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 45,
"text": "The Chromerida is a newly discovered group of algae from Australian corals which comprises some close photosynthetic relatives of the apicomplexans. The first member, Chromera velia, was discovered and first isolated in 2001. The discovery of Chromera velia with similar structure to the apicomplexans, provides an important link in the evolutionary history of the apicomplexans and dinophytes. Their plastids have four membranes, lack chlorophyll c and use the type II form of RuBisCO obtained from a horizontal transfer event.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 46,
"text": "The dinoflagellates are yet another very large and diverse group of protists, around half of which are (at least partially) photosynthetic.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 47,
"text": "Most dinophyte chloroplasts are secondary red algal derived chloroplasts. Many other dinophytes have lost the chloroplast (becoming the nonphotosynthetic kind of dinoflagellate), or replaced it though tertiary endosymbiosis—the engulfment of another eukaryotic algae containing a red algal derived chloroplast. Others replaced their original chloroplast with a green algal derived one.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 48,
"text": "Most dinophyte chloroplasts contain form II RuBisCO, at least the photosynthetic pigments chlorophyll a, chlorophyll c2, beta-carotene, and at least one dinophyte-unique xanthophyll (peridinin, dinoxanthin, or diadinoxanthin), giving many a golden-brown color. All dinophytes store starch in their cytoplasm, and most have chloroplasts with thylakoids arranged in stacks of three.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 49,
"text": "The most common dinophyte chloroplast is the peridinin-type chloroplast, characterized by the carotenoid pigment peridinin in their chloroplasts, along with chlorophyll a and chlorophyll c2. Peridinin is not found in any other group of chloroplasts. The peridinin chloroplast is bounded by three membranes (occasionally two), having lost the red algal endosymbiont's original cell membrane. The outermost membrane is not connected to the endoplasmic reticulum. They contain a pyrenoid, and have triplet-stacked thylakoids. Starch is found outside the chloroplast. An important feature of these chloroplasts is that their chloroplast DNA is highly reduced and fragmented into many small circles. Most of the genome has migrated to the nucleus, and only critical photosynthesis-related genes remain in the chloroplast.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 50,
"text": "The peridinin chloroplast is thought to be the dinophytes' \"original\" chloroplast, which has been lost, reduced, replaced, or has company in several other dinophyte lineages.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 51,
"text": "The fucoxanthin dinophyte lineages (including Karlodinium and Karenia) lost their original red algal derived chloroplast, and replaced it with a new chloroplast derived from a haptophyte endosymbiont. Karlodinium and Karenia probably took up different heterokontophytes. Because the haptophyte chloroplast has four membranes, tertiary endosymbiosis would be expected to create a six membraned chloroplast, adding the haptophyte's cell membrane and the dinophyte's phagosomal vacuole. However, the haptophyte was heavily reduced, stripped of a few membranes and its nucleus, leaving only its chloroplast (with its original double membrane), and possibly one or two additional membranes around it.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 52,
"text": "Fucoxanthin-containing chloroplasts are characterized by having the pigment fucoxanthin (actually 19′-hexanoyloxy-fucoxanthin and/or 19′-butanoyloxy-fucoxanthin) and no peridinin. Fucoxanthin is also found in haptophyte chloroplasts, providing evidence of ancestry.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 53,
"text": "Some dinophytes, like Kryptoperidinium and Durinskia, have a diatom (heterokontophyte)-derived chloroplast. These chloroplasts are bounded by up to five membranes, (depending on whether the entire diatom endosymbiont is counted as the chloroplast, or just the red algal derived chloroplast inside it). The diatom endosymbiont has been reduced relatively little—it still retains its original mitochondria, and has endoplasmic reticulum, ribosomes, a nucleus, and of course, red algal derived chloroplasts—practically a complete cell, all inside the host's endoplasmic reticulum lumen. However the diatom endosymbiont can't store its own food—its storage polysaccharide is found in granules in the dinophyte host's cytoplasm instead. The diatom endosymbiont's nucleus is present, but it probably can't be called a nucleomorph because it shows no sign of genome reduction, and might have even been expanded. Diatoms have been engulfed by dinoflagellates at least three times.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 54,
"text": "The diatom endosymbiont is bounded by a single membrane, inside it are chloroplasts with four membranes. Like the diatom endosymbiont's diatom ancestor, the chloroplasts have triplet thylakoids and pyrenoids.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 55,
"text": "In some of these genera, the diatom endosymbiont's chloroplasts aren't the only chloroplasts in the dinophyte. The original three-membraned peridinin chloroplast is still around, converted to an eyespot.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 56,
"text": "In some groups of mixotrophic protists, like some dinoflagellates (e.g. Dinophysis), chloroplasts are separated from a captured alga and used temporarily. These klepto chloroplasts may only have a lifetime of a few days and are then replaced.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 57,
"text": "Members of the genus Dinophysis have a phycobilin-containing chloroplast taken from a cryptophyte. However, the cryptophyte is not an endosymbiont—only the chloroplast seems to have been taken, and the chloroplast has been stripped of its nucleomorph and outermost two membranes, leaving just a two-membraned chloroplast. Cryptophyte chloroplasts require their nucleomorph to maintain themselves, and Dinophysis species grown in cell culture alone cannot survive, so it is possible (but not confirmed) that the Dinophysis chloroplast is a kleptoplast—if so, Dinophysis chloroplasts wear out and Dinophysis species must continually engulf cryptophytes to obtain new chloroplasts to replace the old ones.",
"title": "Lineages and evolution"
},
{
"paragraph_id": 58,
"text": "Chloroplasts, like other types of plastid, contain a genome separate from that in the cell nucleus. The existence of chloroplast DNA (cpDNA) was identified biochemically in 1959, and confirmed by electron microscopy in 1962. The discoveries that the chloroplast contains ribosomes and performs protein synthesis revealed that the chloroplast is genetically semi-autonomous. Chloroplast DNA was first sequenced in 1986. Since then, hundreds of chloroplast DNAs from various species have been sequenced, but they are mostly those of land plants and green algae—glaucophytes, red algae, and other algal groups are extremely underrepresented, potentially introducing some bias in views of \"typical\" chloroplast DNA structure and content.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 59,
"text": "With few exceptions, most chloroplasts have their entire chloroplast genome combined into a single large circular DNA molecule, typically 120,000–170,000 base pairs long. They can have a contour length of around 30–60 micrometers, and have a mass of about 80–130 million daltons.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 60,
"text": "While usually thought of as a circular molecule, there is some evidence that chloroplast DNA molecules more often take on a linear shape.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 61,
"text": "Many chloroplast DNAs contain two inverted repeats, which separate a long single copy section (LSC) from a short single copy section (SSC). While a given pair of inverted repeats are rarely completely identical, they are always very similar to each other, apparently resulting from concerted evolution.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 62,
"text": "The inverted repeats vary wildly in length, ranging from 4,000 to 25,000 base pairs long each and containing as few as four or as many as over 150 genes. Inverted repeats in plants tend to be at the upper end of this range, each being 20,000–25,000 base pairs long.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 63,
"text": "The inverted repeat regions are highly conserved among land plants, and accumulate few mutations. Similar inverted repeats exist in the genomes of cyanobacteria and the other two chloroplast lineages (glaucophyta and rhodophyceae), suggesting that they predate the chloroplast, though some chloroplast DNAs have since lost or flipped the inverted repeats (making them direct repeats). It is possible that the inverted repeats help stabilize the rest of the chloroplast genome, as chloroplast DNAs which have lost some of the inverted repeat segments tend to get rearranged more.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 64,
"text": "New chloroplasts may contain up to 100 copies of their DNA, though the number of chloroplast DNA copies decreases to about 15–20 as the chloroplasts age. They are usually packed into nucleoids, which can contain several identical chloroplast DNA rings. Many nucleoids can be found in each chloroplast. In primitive red algae, the chloroplast DNA nucleoids are clustered in the center of the chloroplast, while in green plants and green algae, the nucleoids are dispersed throughout the stroma.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 65,
"text": "Though chloroplast DNA is not associated with true histones, in red algae, similar proteins that tightly pack each chloroplast DNA ring into a nucleoid have been found.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 66,
"text": "In chloroplasts of the moss Physcomitrella patens, the DNA mismatch repair protein Msh1 interacts with the recombinational repair proteins RecA and RecG to maintain chloroplast genome stability. In chloroplasts of the plant Arabidopsis thaliana the RecA protein maintains the integrity of the chloroplast's DNA by a process that likely involves the recombinational repair of DNA damage.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 67,
"text": "The mechanism for chloroplast DNA (cpDNA) replication has not been conclusively determined, but two main models have been proposed. Scientists have attempted to observe chloroplast replication via electron microscopy since the 1970s. The results of the microscopy experiments led to the idea that chloroplast DNA replicates using a double displacement loop (D-loop). As the D-loop moves through the circular DNA, it adopts a theta intermediary form, also known as a Cairns replication intermediate, and completes replication with a rolling circle mechanism. Transcription starts at specific points of origin. Multiple replication forks open up, allowing replication machinery to transcribe the DNA. As replication continues, the forks grow and eventually converge. The new cpDNA structures separate, creating daughter cpDNA chromosomes.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 68,
"text": "In addition to the early microscopy experiments, this model is also supported by the amounts of deamination seen in cpDNA. Deamination occurs when an amino group is lost and is a mutation that often results in base changes. When adenine is deaminated, it becomes hypoxanthine. Hypoxanthine can bind to cytosine, and when the XC base pair is replicated, it becomes a GC (thus, an A → G base change).",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 69,
"text": "In cpDNA, there are several A → G deamination gradients. DNA becomes susceptible to deamination events when it is single stranded. When replication forks form, the strand not being copied is single stranded, and thus at risk for A → G deamination. Therefore, gradients in deamination indicate that replication forks were most likely present and the direction that they initially opened (the highest gradient is most likely nearest the start site because it was single stranded for the longest amount of time). This mechanism is still the leading theory today; however, a second theory suggests that most cpDNA is actually linear and replicates through homologous recombination. It further contends that only a minority of the genetic material is kept in circular chromosomes while the rest is in branched, linear, or other complex structures.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 70,
"text": "One of competing model for cpDNA replication asserts that most cpDNA is linear and participates in homologous recombination and replication structures similar to the linear and circular DNA structures of bacteriophage T4. It has been established that some plants have linear cpDNA, such as maize, and that more species still contain complex structures that scientists do not yet understand. When the original experiments on cpDNA were performed, scientists did notice linear structures; however, they attributed these linear forms to broken circles. If the branched and complex structures seen in cpDNA experiments are real and not artifacts of concatenated circular DNA or broken circles, then a D-loop mechanism of replication is insufficient to explain how those structures would replicate. At the same time, homologous recombination does not expand the multiple A --> G gradients seen in plastomes. Because of the failure to explain the deamination gradient as well as the numerous plant species that have been shown to have circular cpDNA, the predominant theory continues to hold that most cpDNA is circular and most likely replicates via a D loop mechanism.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 71,
"text": "The chloroplast genome most commonly includes around 100 genes that code for a variety of things, mostly to do with the protein pipeline and photosynthesis. As in prokaryotes, genes in chloroplast DNA are organized into operons. Unlike prokaryotic DNA molecules, chloroplast DNA molecules contain introns (plant mitochondrial DNAs do too, but not human mtDNAs).",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 72,
"text": "Among land plants, the contents of the chloroplast genome are fairly similar.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 73,
"text": "Over time, many parts of the chloroplast genome were transferred to the nuclear genome of the host, a process called endosymbiotic gene transfer. As a result, the chloroplast genome is heavily reduced compared to that of free-living cyanobacteria. Chloroplasts may contain 60–100 genes whereas cyanobacteria often have more than 1500 genes in their genome. Recently, a plastid without a genome was found, demonstrating chloroplasts can lose their genome during endosymbiotic the gene transfer process.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 74,
"text": "Endosymbiotic gene transfer is how we know about the lost chloroplasts in many CASH lineages. Even if a chloroplast is eventually lost, the genes it donated to the former host's nucleus persist, providing evidence for the lost chloroplast's existence. For example, while diatoms (a heterokontophyte) now have a red algal derived chloroplast, the presence of many green algal genes in the diatom nucleus provide evidence that the diatom ancestor had a green algal derived chloroplast at some point, which was subsequently replaced by the red chloroplast.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 75,
"text": "In land plants, some 11–14% of the DNA in their nuclei can be traced back to the chloroplast, up to 18% in Arabidopsis, corresponding to about 4,500 protein-coding genes. There have been a few recent transfers of genes from the chloroplast DNA to the nuclear genome in land plants.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 76,
"text": "Of the approximately 3000 proteins found in chloroplasts, some 95% of them are encoded by nuclear genes. Many of the chloroplast's protein complexes consist of subunits from both the chloroplast genome and the host's nuclear genome. As a result, protein synthesis must be coordinated between the chloroplast and the nucleus. The chloroplast is mostly under nuclear control, though chloroplasts can also give out signals regulating gene expression in the nucleus, called retrograde signaling. Recent research indicates that parts of the retrograde signaling network once considered characteristic for land plants emerged already in an algal progenitor, integrating into co-expressed cohorts of genes in the closest algal relatives of land plants.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 77,
"text": "Protein synthesis within chloroplasts relies on two RNA polymerases. One is coded by the chloroplast DNA, the other is of nuclear origin. The two RNA polymerases may recognize and bind to different kinds of promoters within the chloroplast genome. The ribosomes in chloroplasts are similar to bacterial ribosomes.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 78,
"text": "Because so many chloroplast genes have been moved to the nucleus, many proteins that would originally have been translated in the chloroplast are now synthesized in the cytoplasm of the plant cell. These proteins must be directed back to the chloroplast, and imported through at least two chloroplast membranes.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 79,
"text": "Curiously, around half of the protein products of transferred genes aren't even targeted back to the chloroplast. Many became exaptations, taking on new functions like participating in cell division, protein routing, and even disease resistance. A few chloroplast genes found new homes in the mitochondrial genome—most became nonfunctional pseudogenes, though a few tRNA genes still work in the mitochondrion. Some transferred chloroplast DNA protein products get directed to the secretory pathway, though many secondary plastids are bounded by an outermost membrane derived from the host's cell membrane, and therefore topologically outside of the cell because to reach the chloroplast from the cytosol, the cell membrane must be crossed, which signifies entrance into the extracellular space. In those cases, chloroplast-targeted proteins do initially travel along the secretory pathway.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 80,
"text": "Because the cell acquiring a chloroplast already had mitochondria (and peroxisomes, and a cell membrane for secretion), the new chloroplast host had to develop a unique protein targeting system to avoid having chloroplast proteins being sent to the wrong organelle.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 81,
"text": "In most, but not all cases, nuclear-encoded chloroplast proteins are translated with a cleavable transit peptide that's added to the N-terminus of the protein precursor. Sometimes the transit sequence is found on the C-terminus of the protein, or within the functional part of the protein.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 82,
"text": "After a chloroplast polypeptide is synthesized on a ribosome in the cytosol, an enzyme specific to chloroplast proteins phosphorylates, or adds a phosphate group to many (but not all) of them in their transit sequences. Phosphorylation helps many proteins bind the polypeptide, keeping it from folding prematurely. This is important because it prevents chloroplast proteins from assuming their active form and carrying out their chloroplast functions in the wrong place—the cytosol. At the same time, they have to keep just enough shape so that they can be recognized by the chloroplast. These proteins also help the polypeptide get imported into the chloroplast.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 83,
"text": "From here, chloroplast proteins bound for the stroma must pass through two protein complexes—the TOC complex, or translocon on the outer chloroplast membrane, and the TIC translocon, or translocon on the inner chloroplast membrane translocon. Chloroplast polypeptide chains probably often travel through the two complexes at the same time, but the TIC complex can also retrieve preproteins lost in the intermembrane space.",
"title": "Chloroplast DNA"
},
{
"paragraph_id": 84,
"text": "In land plants, chloroplasts are generally lens-shaped, 3–10 μm in diameter and 1–3 μm thick. Corn seedling chloroplasts are ≈20 µm in volume. Greater diversity in chloroplast shapes exists among the algae, which often contain a single chloroplast that can be shaped like a net (e.g., Oedogonium), a cup (e.g., Chlamydomonas), a ribbon-like spiral around the edges of the cell (e.g., Spirogyra), or slightly twisted bands at the cell edges (e.g., Sirogonium). Some algae have two chloroplasts in each cell; they are star-shaped in Zygnema, or may follow the shape of half the cell in order Desmidiales. In some algae, the chloroplast takes up most of the cell, with pockets for the nucleus and other organelles, for example, some species of Chlorella have a cup-shaped chloroplast that occupies much of the cell.",
"title": "Structure"
},
{
"paragraph_id": 85,
"text": "All chloroplasts have at least three membrane systems—the outer chloroplast membrane, the inner chloroplast membrane, and the thylakoid system. Chloroplasts that are the product of secondary endosymbiosis may have additional membranes surrounding these three. Inside the outer and inner chloroplast membranes is the chloroplast stroma, a semi-gel-like fluid that makes up much of a chloroplast's volume, and in which the thylakoid system floats.",
"title": "Structure"
},
{
"paragraph_id": 86,
"text": "There are some common misconceptions about the outer and inner chloroplast membranes. The fact that chloroplasts are surrounded by a double membrane is often cited as evidence that they are the descendants of endosymbiotic cyanobacteria. This is often interpreted as meaning the outer chloroplast membrane is the product of the host's cell membrane infolding to form a vesicle to surround the ancestral cyanobacterium—which is not true—both chloroplast membranes are homologous to the cyanobacterium's original double membranes.",
"title": "Structure"
},
{
"paragraph_id": 87,
"text": "The chloroplast double membrane is also often compared to the mitochondrial double membrane. This is not a valid comparison—the inner mitochondria membrane is used to run proton pumps and carry out oxidative phosphorylation across to generate ATP energy. The only chloroplast structure that can considered analogous to it is the internal thylakoid system. Even so, in terms of \"in-out\", the direction of chloroplast H ion flow is in the opposite direction compared to oxidative phosphorylation in mitochondria. In addition, in terms of function, the inner chloroplast membrane, which regulates metabolite passage and synthesizes some materials, has no counterpart in the mitochondrion.",
"title": "Structure"
},
{
"paragraph_id": 88,
"text": "The outer chloroplast membrane is a semi-porous membrane that small molecules and ions can easily diffuse across. However, it is not permeable to larger proteins, so chloroplast polypeptides being synthesized in the cell cytoplasm must be transported across the outer chloroplast membrane by the TOC complex, or translocon on the outer chloroplast membrane.",
"title": "Structure"
},
{
"paragraph_id": 89,
"text": "The chloroplast membranes sometimes protrude out into the cytoplasm, forming a stromule, or stroma-containing tubule. Stromules are very rare in chloroplasts, and are much more common in other plastids like chromoplasts and amyloplasts in petals and roots, respectively. They may exist to increase the chloroplast's surface area for cross-membrane transport, because they are often branched and tangled with the endoplasmic reticulum. When they were first observed in 1962, some plant biologists dismissed the structures as artifactual, claiming that stromules were just oddly shaped chloroplasts with constricted regions or dividing chloroplasts. However, there is a growing body of evidence that stromules are functional, integral features of plant cell plastids, not merely artifacts.",
"title": "Structure"
},
{
"paragraph_id": 90,
"text": "Usually, a thin intermembrane space about 10–20 nanometers thick exists between the outer and inner chloroplast membranes.",
"title": "Structure"
},
{
"paragraph_id": 91,
"text": "Glaucophyte algal chloroplasts have a peptidoglycan layer between the chloroplast membranes. It corresponds to the peptidoglycan cell wall of their cyanobacterial ancestors, which is located between their two cell membranes. These chloroplasts are called muroplasts (from Latin \"mura\", meaning \"wall\"). Other chloroplasts were assumed to have lost the cyanobacterial wall, leaving an intermembrane space between the two chloroplast envelope membranes, but has since been found also in moss, lycophytes and ferns.",
"title": "Structure"
},
{
"paragraph_id": 92,
"text": "The inner chloroplast membrane borders the stroma and regulates passage of materials in and out of the chloroplast. After passing through the TOC complex in the outer chloroplast membrane, polypeptides must pass through the TIC complex (translocon on the inner chloroplast membrane) which is located in the inner chloroplast membrane.",
"title": "Structure"
},
{
"paragraph_id": 93,
"text": "In addition to regulating the passage of materials, the inner chloroplast membrane is where fatty acids, lipids, and carotenoids are synthesized.",
"title": "Structure"
},
{
"paragraph_id": 94,
"text": "Some chloroplasts contain a structure called the chloroplast peripheral reticulum. It is often found in the chloroplasts of C4 plants, though it has also been found in some C3 angiosperms, and even some gymnosperms. The chloroplast peripheral reticulum consists of a maze of membranous tubes and vesicles continuous with the inner chloroplast membrane that extends into the internal stromal fluid of the chloroplast. Its purpose is thought to be to increase the chloroplast's surface area for cross-membrane transport between its stroma and the cell cytoplasm. The small vesicles sometimes observed may serve as transport vesicles to shuttle stuff between the thylakoids and intermembrane space.",
"title": "Structure"
},
{
"paragraph_id": 95,
"text": "The protein-rich, alkaline, aqueous fluid within the inner chloroplast membrane and outside of the thylakoid space is called the stroma, which corresponds to the cytosol of the original cyanobacterium. Nucleoids of chloroplast DNA, chloroplast ribosomes, the thylakoid system with plastoglobuli, starch granules, and many proteins can be found floating around in it. The Calvin cycle, which fixes CO2 into G3P takes place in the stroma.",
"title": "Structure"
},
{
"paragraph_id": 96,
"text": "Chloroplasts have their own ribosomes, which they use to synthesize a small fraction of their proteins. Chloroplast ribosomes are about two-thirds the size of cytoplasmic ribosomes (around 17 nm vs 25 nm). They take mRNAs transcribed from the chloroplast DNA and translate them into protein. While similar to bacterial ribosomes, chloroplast translation is more complex than in bacteria, so chloroplast ribosomes include some chloroplast-unique features.",
"title": "Structure"
},
{
"paragraph_id": 97,
"text": "Small subunit ribosomal RNAs in several Chlorophyta and euglenid chloroplasts lack motifs for Shine-Dalgarno sequence recognition, which is considered essential for translation initiation in most chloroplasts and prokaryotes. Such loss is also rarely observed in other plastids and prokaryotes. An additional 4.5S rRNA with homology to the 3' tail of 23S is found in \"higher\" plants.",
"title": "Structure"
},
{
"paragraph_id": 98,
"text": "Plastoglobuli (singular plastoglobulus, sometimes spelled plastoglobule(s)), are spherical bubbles of lipids and proteins about 45–60 nanometers across. They are surrounded by a lipid monolayer. Plastoglobuli are found in all chloroplasts, but become more common when the chloroplast is under oxidative stress, or when it ages and transitions into a gerontoplast. Plastoglobuli also exhibit a greater size variation under these conditions. They are also common in etioplasts, but decrease in number as the etioplasts mature into chloroplasts.",
"title": "Structure"
},
{
"paragraph_id": 99,
"text": "Plastoglobuli contain both structural proteins and enzymes involved in lipid synthesis and metabolism. They contain many types of lipids including plastoquinone, vitamin E, carotenoids and chlorophylls.",
"title": "Structure"
},
{
"paragraph_id": 100,
"text": "Plastoglobuli were once thought to be free-floating in the stroma, but it is now thought that they are permanently attached either to a thylakoid or to another plastoglobulus attached to a thylakoid, a configuration that allows a plastoglobulus to exchange its contents with the thylakoid network. In normal green chloroplasts, the vast majority of plastoglobuli occur singularly, attached directly to their parent thylakoid. In old or stressed chloroplasts, plastoglobuli tend to occur in linked groups or chains, still always anchored to a thylakoid.",
"title": "Structure"
},
{
"paragraph_id": 101,
"text": "Plastoglobuli form when a bubble appears between the layers of the lipid bilayer of the thylakoid membrane, or bud from existing plastoglobuli—though they never detach and float off into the stroma. Practically all plastoglobuli form on or near the highly curved edges of the thylakoid disks or sheets. They are also more common on stromal thylakoids than on granal ones.",
"title": "Structure"
},
{
"paragraph_id": 102,
"text": "Starch granules are very common in chloroplasts, typically taking up 15% of the organelle's volume, though in some other plastids like amyloplasts, they can be big enough to distort the shape of the organelle. Starch granules are simply accumulations of starch in the stroma, and are not bounded by a membrane.",
"title": "Structure"
},
{
"paragraph_id": 103,
"text": "Starch granules appear and grow throughout the day, as the chloroplast synthesizes sugars, and are consumed at night to fuel respiration and continue sugar export into the phloem, though in mature chloroplasts, it is rare for a starch granule to be completely consumed or for a new granule to accumulate.",
"title": "Structure"
},
{
"paragraph_id": 104,
"text": "Starch granules vary in composition and location across different chloroplast lineages. In red algae, starch granules are found in the cytoplasm rather than in the chloroplast. In C4 plants, mesophyll chloroplasts, which do not synthesize sugars, lack starch granules.",
"title": "Structure"
},
{
"paragraph_id": 105,
"text": "The chloroplast stroma contains many proteins, though the most common and important is RuBisCO, which is probably also the most abundant protein on the planet. RuBisCO is the enzyme that fixes CO2 into sugar molecules. In C3 plants, RuBisCO is abundant in all chloroplasts, though in C4 plants, it is confined to the bundle sheath chloroplasts, where the Calvin cycle is carried out in C4 plants.",
"title": "Structure"
},
{
"paragraph_id": 106,
"text": "The chloroplasts of some hornworts and algae contain structures called pyrenoids. They are not found in higher plants. Pyrenoids are roughly spherical and highly refractive bodies which are a site of starch accumulation in plants that contain them. They consist of a matrix opaque to electrons, surrounded by two hemispherical starch plates. The starch is accumulated as the pyrenoids mature. In algae with carbon concentrating mechanisms, the enzyme RuBisCO is found in the pyrenoids. Starch can also accumulate around the pyrenoids when CO2 is scarce. Pyrenoids can divide to form new pyrenoids, or be produced \"de novo\".",
"title": "Structure"
},
{
"paragraph_id": 107,
"text": "Thylakoids (sometimes spelled thylakoïds), are small interconnected sacks which contain the membranes that the light reactions of photosynthesis take place on. The word thylakoid comes from the Greek word thylakos which means \"sack\".",
"title": "Structure"
},
{
"paragraph_id": 108,
"text": "Suspended within the chloroplast stroma is the thylakoid system, a highly dynamic collection of membranous sacks called thylakoids where chlorophyll is found and the light reactions of photosynthesis happen. In most vascular plant chloroplasts, the thylakoids are arranged in stacks called grana, though in certain C4 plant chloroplasts and some algal chloroplasts, the thylakoids are free floating.",
"title": "Structure"
},
{
"paragraph_id": 109,
"text": "Using a light microscope, it is just barely possible to see tiny green granules—which were named grana. With electron microscopy, it became possible to see the thylakoid system in more detail, revealing it to consist of stacks of flat thylakoids which made up the grana, and long interconnecting stromal thylakoids which linked different grana. In the transmission electron microscope, thylakoid membranes appear as alternating light-and-dark bands, 8.5 nanometers thick.",
"title": "Structure"
},
{
"paragraph_id": 110,
"text": "For a long time, the three-dimensional structure of the thylakoid membrane system had been unknown or disputed. Many models have been proposed, the most prevalent being the helical model, in which granum stacks of thylakoids are wrapped by helical stromal thylakoids. Another model known as the 'bifurcation model', which was based on the first electron tomography study of plant thylakoid membranes, depicts the stromal membranes as wide lamellar sheets perpendicular to the grana columns which bifurcates into multiple parallel discs forming the granum-stroma assembly. The helical model was supported by several additional works, but ultimately it was determined in 2019 that features from both the helical and bifurcation models are consolidated by newly discovered left-handed helical membrane junctions. Likely for ease, the thylakoid system is still commonly depicted by older \"hub and spoke\" models where the grana are connected to each other by tubes of stromal thylakoids.",
"title": "Structure"
},
{
"paragraph_id": 111,
"text": "Grana consist of a stacks of flattened circular granal thylakoids that resemble pancakes. Each granum can contain anywhere from two to a hundred thylakoids, though grana with 10–20 thylakoids are most common. Wrapped around the grana are multiple parallel right-handed helical stromal thylakoids, also known as frets or lamellar thylakoids. The helices ascend at an angle of ~20°, connecting to each granal thylakoid at a bridge-like slit junction.",
"title": "Structure"
},
{
"paragraph_id": 112,
"text": "The stroma lamellae extend as large sheets perpendicular to the grana columns. These sheets are connected to the right-handed helices either directly or through bifurcations that form left-handed helical membrane surfaces. The left-handed helical surfaces have a similar tilt angle to the right-handed helices (~20°), but ¼ the pitch. Approximately 4 left-handed helical junctions are present per granum, resulting in a pitch-balanced array of right- and left-handed helical membrane surfaces of different radii and pitch that consolidate the network with minimal surface and bending energies. While different parts of the thylakoid system contain different membrane proteins, the thylakoid membranes are continuous and the thylakoid space they enclose form a single continuous labyrinth.",
"title": "Structure"
},
{
"paragraph_id": 113,
"text": "Embedded in the thylakoid membranes are important protein complexes which carry out the light reactions of photosynthesis. Photosystem II and photosystem I contain light-harvesting complexes with chlorophyll and carotenoids that absorb light energy and use it to energize electrons. Molecules in the thylakoid membrane use the energized electrons to pump hydrogen ions into the thylakoid space, decreasing the pH and turning it acidic. ATP synthase is a large protein complex that harnesses the concentration gradient of the hydrogen ions in the thylakoid space to generate ATP energy as the hydrogen ions flow back out into the stroma—much like a dam turbine.",
"title": "Structure"
},
{
"paragraph_id": 114,
"text": "There are two types of thylakoids—granal thylakoids, which are arranged in grana, and stromal thylakoids, which are in contact with the stroma. Granal thylakoids are pancake-shaped circular disks about 300–600 nanometers in diameter. Stromal thylakoids are helicoid sheets that spiral around grana. The flat tops and bottoms of granal thylakoids contain only the relatively flat photosystem II protein complex. This allows them to stack tightly, forming grana with many layers of tightly appressed membrane, called granal membrane, increasing stability and surface area for light capture.",
"title": "Structure"
},
{
"paragraph_id": 115,
"text": "In contrast, photosystem I and ATP synthase are large protein complexes which jut out into the stroma. They can't fit in the appressed granal membranes, and so are found in the stromal thylakoid membrane—the edges of the granal thylakoid disks and the stromal thylakoids. These large protein complexes may act as spacers between the sheets of stromal thylakoids.",
"title": "Structure"
},
{
"paragraph_id": 116,
"text": "The number of thylakoids and the total thylakoid area of a chloroplast is influenced by light exposure. Shaded chloroplasts contain larger and more grana with more thylakoid membrane area than chloroplasts exposed to bright light, which have smaller and fewer grana and less thylakoid area. Thylakoid extent can change within minutes of light exposure or removal.",
"title": "Structure"
},
{
"paragraph_id": 117,
"text": "Inside the photosystems embedded in chloroplast thylakoid membranes are various photosynthetic pigments, which absorb and transfer light energy. The types of pigments found are different in various groups of chloroplasts, and are responsible for a wide variety of chloroplast colorations.",
"title": "Structure"
},
{
"paragraph_id": 118,
"text": "Chlorophyll a is found in all chloroplasts, as well as their cyanobacterial ancestors. Chlorophyll a is a blue-green pigment partially responsible for giving most cyanobacteria and chloroplasts their color. Other forms of chlorophyll exist, such as the accessory pigments chlorophyll b, chlorophyll c, chlorophyll d, and chlorophyll f.",
"title": "Structure"
},
{
"paragraph_id": 119,
"text": "Chlorophyll b is an olive green pigment found only in the chloroplasts of plants, green algae, any secondary chloroplasts obtained through the secondary endosymbiosis of a green alga, and a few cyanobacteria. It is the chlorophylls a and b together that make most plant and green algal chloroplasts green.",
"title": "Structure"
},
{
"paragraph_id": 120,
"text": "Chlorophyll c is mainly found in secondary endosymbiotic chloroplasts that originated from a red alga, although it is not found in chloroplasts of red algae themselves. Chlorophyll c is also found in some green algae and cyanobacteria.",
"title": "Structure"
},
{
"paragraph_id": 121,
"text": "Chlorophylls d and f are pigments found only in some cyanobacteria.",
"title": "Structure"
},
{
"paragraph_id": 122,
"text": "In addition to chlorophylls, another group of yellow–orange pigments called carotenoids are also found in the photosystems. There are about thirty photosynthetic carotenoids. They help transfer and dissipate excess energy, and their bright colors sometimes override the chlorophyll green, like during the fall, when the leaves of some land plants change color. β-carotene is a bright red-orange carotenoid found in nearly all chloroplasts, like chlorophyll a. Xanthophylls, especially the orange-red zeaxanthin, are also common. Many other forms of carotenoids exist that are only found in certain groups of chloroplasts.",
"title": "Structure"
},
{
"paragraph_id": 123,
"text": "Phycobilins are a third group of pigments found in cyanobacteria, and glaucophyte, red algal, and cryptophyte chloroplasts. Phycobilins come in all colors, though phycoerytherin is one of the pigments that makes many red algae red. Phycobilins often organize into relatively large protein complexes about 40 nanometers across called phycobilisomes. Like photosystem I and ATP synthase, phycobilisomes jut into the stroma, preventing thylakoid stacking in red algal chloroplasts. Cryptophyte chloroplasts and some cyanobacteria don't have their phycobilin pigments organized into phycobilisomes, and keep them in their thylakoid space instead.",
"title": "Structure"
},
{
"paragraph_id": 124,
"text": "To fix carbon dioxide into sugar molecules in the process of photosynthesis, chloroplasts use an enzyme called RuBisCO. RuBisCO has trouble distinguishing between carbon dioxide and oxygen, so at high oxygen concentrations, RuBisCO starts accidentally adding oxygen to sugar precursors. This has the result of ATP energy being wasted and CO2 being released, all with no sugar being produced. This is a big problem, since O2 is produced by the initial light reactions of photosynthesis, causing issues down the line in the Calvin cycle which uses RuBisCO.",
"title": "Structure"
},
{
"paragraph_id": 125,
"text": "C4 plants evolved a way to solve this—by spatially separating the light reactions and the Calvin cycle. The light reactions, which store light energy in ATP and NADPH, are done in the mesophyll cells of a C4 leaf. The Calvin cycle, which uses the stored energy to make sugar using RuBisCO, is done in the bundle sheath cells, a layer of cells surrounding a vein in a leaf.",
"title": "Structure"
},
{
"paragraph_id": 126,
"text": "As a result, chloroplasts in C4 mesophyll cells and bundle sheath cells are specialized for each stage of photosynthesis. In mesophyll cells, chloroplasts are specialized for the light reactions, so they lack RuBisCO, and have normal grana and thylakoids, which they use to make ATP and NADPH, as well as oxygen. They store CO2 in a four-carbon compound, which is why the process is called C4 photosynthesis. The four-carbon compound is then transported to the bundle sheath chloroplasts, where it drops off CO2 and returns to the mesophyll. Bundle sheath chloroplasts do not carry out the light reactions, preventing oxygen from building up in them and disrupting RuBisCO activity. Because of this, they lack thylakoids organized into grana stacks—though bundle sheath chloroplasts still have free-floating thylakoids in the stroma where they still carry out cyclic electron flow, a light-driven method of synthesizing ATP to power the Calvin cycle without generating oxygen. They lack photosystem II, and only have photosystem I—the only protein complex needed for cyclic electron flow. Because the job of bundle sheath chloroplasts is to carry out the Calvin cycle and make sugar, they often contain large starch grains.",
"title": "Structure"
},
{
"paragraph_id": 127,
"text": "Both types of chloroplast contain large amounts of chloroplast peripheral reticulum, which they use to get more surface area to transport stuff in and out of them. Mesophyll chloroplasts have a little more peripheral reticulum than bundle sheath chloroplasts.",
"title": "Structure"
},
{
"paragraph_id": 128,
"text": "Not all cells in a multicellular plant contain chloroplasts. All green parts of a plant contain chloroplasts—the chloroplasts, or more specifically, the chlorophyll in them are what make the photosynthetic parts of a plant green. The plant cells which contain chloroplasts are usually parenchyma cells, though chloroplasts can also be found in collenchyma tissue. A plant cell which contains chloroplasts is known as a chlorenchyma cell. A typical chlorenchyma cell of a land plant contains about 10 to 100 chloroplasts.",
"title": "Location"
},
{
"paragraph_id": 129,
"text": "In some plants such as cacti, chloroplasts are found in the stems, though in most plants, chloroplasts are concentrated in the leaves. One square millimeter of leaf tissue can contain half a million chloroplasts. Within a leaf, chloroplasts are mainly found in the mesophyll layers of a leaf, and the guard cells of stomata. Palisade mesophyll cells can contain 30–70 chloroplasts per cell, while stomatal guard cells contain only around 8–15 per cell, as well as much less chlorophyll. Chloroplasts can also be found in the bundle sheath cells of a leaf, especially in C4 plants, which carry out the Calvin cycle in their bundle sheath cells. They are often absent from the epidermis of a leaf.",
"title": "Location"
},
{
"paragraph_id": 130,
"text": "The chloroplasts of plant and algal cells can orient themselves to best suit the available light. In low-light conditions, they will spread out in a sheet—maximizing the surface area to absorb light. Under intense light, they will seek shelter by aligning in vertical columns along the plant cell's cell wall or turning sideways so that light strikes them edge-on. This reduces exposure and protects them from photooxidative damage. This ability to distribute chloroplasts so that they can take shelter behind each other or spread out may be the reason why land plants evolved to have many small chloroplasts instead of a few big ones. Chloroplast movement is considered one of the most closely regulated stimulus-response systems that can be found in plants. Mitochondria have also been observed to follow chloroplasts as they move.",
"title": "Location"
},
{
"paragraph_id": 131,
"text": "In higher plants, chloroplast movement is run by phototropins, blue light photoreceptors also responsible for plant phototropism. In some algae, mosses, ferns, and flowering plants, chloroplast movement is influenced by red light in addition to blue light, though very long red wavelengths inhibit movement rather than speeding it up. Blue light generally causes chloroplasts to seek shelter, while red light draws them out to maximize light absorption.",
"title": "Location"
},
{
"paragraph_id": 132,
"text": "Studies of Vallisneria gigantea, an aquatic flowering plant, have shown that chloroplasts can get moving within five minutes of light exposure, though they don't initially show any net directionality. They may move along microfilament tracks, and the fact that the microfilament mesh changes shape to form a honeycomb structure surrounding the chloroplasts after they have moved suggests that microfilaments may help to anchor chloroplasts in place.",
"title": "Location"
},
{
"paragraph_id": 133,
"text": "Unlike most epidermal cells, the guard cells of plant stomata contain relatively well-developed chloroplasts. However, exactly what they do is controversial.",
"title": "Function and chemistry"
},
{
"paragraph_id": 134,
"text": "Plants lack specialized immune cells—all plant cells participate in the plant immune response. Chloroplasts, along with the nucleus, cell membrane, and endoplasmic reticulum, are key players in pathogen defense. Due to its role in a plant cell's immune response, pathogens frequently target the chloroplast.",
"title": "Function and chemistry"
},
{
"paragraph_id": 135,
"text": "Plants have two main immune responses—the hypersensitive response, in which infected cells seal themselves off and undergo programmed cell death, and systemic acquired resistance, where infected cells release signals warning the rest of the plant of a pathogen's presence. Chloroplasts stimulate both responses by purposely damaging their photosynthetic system, producing reactive oxygen species. High levels of reactive oxygen species will cause the hypersensitive response. The reactive oxygen species also directly kill any pathogens within the cell. Lower levels of reactive oxygen species initiate systemic acquired resistance, triggering defense-molecule production in the rest of the plant.",
"title": "Function and chemistry"
},
{
"paragraph_id": 136,
"text": "In some plants, chloroplasts are known to move closer to the infection site and the nucleus during an infection.",
"title": "Function and chemistry"
},
{
"paragraph_id": 137,
"text": "Chloroplasts can serve as cellular sensors. After detecting stress in a cell, which might be due to a pathogen, chloroplasts begin producing molecules like salicylic acid, jasmonic acid, nitric oxide and reactive oxygen species which can serve as defense-signals. As cellular signals, reactive oxygen species are unstable molecules, so they probably don't leave the chloroplast, but instead pass on their signal to an unknown second messenger molecule. All these molecules initiate retrograde signaling—signals from the chloroplast that regulate gene expression in the nucleus.",
"title": "Function and chemistry"
},
{
"paragraph_id": 138,
"text": "In addition to defense signaling, chloroplasts, with the help of the peroxisomes, help synthesize an important defense molecule, jasmonate. Chloroplasts synthesize all the fatty acids in a plant cell—linoleic acid, a fatty acid, is a precursor to jasmonate.",
"title": "Function and chemistry"
},
{
"paragraph_id": 139,
"text": "One of the main functions of the chloroplast is its role in photosynthesis, the process by which light is transformed into chemical energy, to subsequently produce food in the form of sugars. Water (H2O) and carbon dioxide (CO2) are used in photosynthesis, and sugar and oxygen (O2) is made, using light energy. Photosynthesis is divided into two stages—the light reactions, where water is split to produce oxygen, and the dark reactions, or Calvin cycle, which builds sugar molecules from carbon dioxide. The two phases are linked by the energy carriers adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADP).",
"title": "Function and chemistry"
},
{
"paragraph_id": 140,
"text": "The light reactions take place on the thylakoid membranes. They take light energy and store it in NADPH, a form of NADP, and ATP to fuel the dark reactions.",
"title": "Function and chemistry"
},
{
"paragraph_id": 141,
"text": "ATP is the phosphorylated version of adenosine diphosphate (ADP), which stores energy in a cell and powers most cellular activities. ATP is the energized form, while ADP is the (partially) depleted form. NADP is an electron carrier which ferries high energy electrons. In the light reactions, it gets reduced, meaning it picks up electrons, becoming NADPH.",
"title": "Function and chemistry"
},
{
"paragraph_id": 142,
"text": "Like mitochondria, chloroplasts use the potential energy stored in an H, or hydrogen ion, gradient to generate ATP energy. The two photosystems capture light energy to energize electrons taken from water, and release them down an electron transport chain. The molecules between the photosystems harness the electrons' energy to pump hydrogen ions into the thylakoid space, creating a concentration gradient, with more hydrogen ions (up to a thousand times as many) inside the thylakoid system than in the stroma. The hydrogen ions in the thylakoid space then diffuse back down their concentration gradient, flowing back out into the stroma through ATP synthase. ATP synthase uses the energy from the flowing hydrogen ions to phosphorylate adenosine diphosphate into adenosine triphosphate, or ATP. Because chloroplast ATP synthase projects out into the stroma, the ATP is synthesized there, in position to be used in the dark reactions.",
"title": "Function and chemistry"
},
{
"paragraph_id": 143,
"text": "Electrons are often removed from the electron transport chains to charge NADP with electrons, reducing it to NADPH. Like ATP synthase, ferredoxin-NADP reductase, the enzyme that reduces NADP, releases the NADPH it makes into the stroma, right where it is needed for the dark reactions.",
"title": "Function and chemistry"
},
{
"paragraph_id": 144,
"text": "Because NADP reduction removes electrons from the electron transport chains, they must be replaced—the job of photosystem II, which splits water molecules (H2O) to obtain the electrons from its hydrogen atoms.",
"title": "Function and chemistry"
},
{
"paragraph_id": 145,
"text": "While photosystem II photolyzes water to obtain and energize new electrons, photosystem I simply reenergizes depleted electrons at the end of an electron transport chain. Normally, the reenergized electrons are taken by NADP, though sometimes they can flow back down more H-pumping electron transport chains to transport more hydrogen ions into the thylakoid space to generate more ATP. This is termed cyclic photophosphorylation because the electrons are recycled. Cyclic photophosphorylation is common in C4 plants, which need more ATP than NADPH.",
"title": "Function and chemistry"
},
{
"paragraph_id": 146,
"text": "The Calvin cycle, also known as the dark reactions, is a series of biochemical reactions that fixes CO2 into G3P sugar molecules and uses the energy and electrons from the ATP and NADPH made in the light reactions. The Calvin cycle takes place in the stroma of the chloroplast.",
"title": "Function and chemistry"
},
{
"paragraph_id": 147,
"text": "While named \"the dark reactions\", in most plants, they take place in the light, since the dark reactions are dependent on the products of the light reactions.",
"title": "Function and chemistry"
},
{
"paragraph_id": 148,
"text": "The Calvin cycle starts by using the enzyme RuBisCO to fix CO2 into five-carbon Ribulose bisphosphate (RuBP) molecules. The result is unstable six-carbon molecules that immediately break down into three-carbon molecules called 3-phosphoglyceric acid, or 3-PGA. The ATP and NADPH made in the light reactions is used to convert the 3-PGA into glyceraldehyde-3-phosphate, or G3P sugar molecules. Most of the G3P molecules are recycled back into RuBP using energy from more ATP, but one out of every six produced leaves the cycle—the end product of the dark reactions.",
"title": "Function and chemistry"
},
{
"paragraph_id": 149,
"text": "Glyceraldehyde-3-phosphate can double up to form larger sugar molecules like glucose and fructose. These molecules are processed, and from them, the still larger sucrose, a disaccharide commonly known as table sugar, is made, though this process takes place outside of the chloroplast, in the cytoplasm.",
"title": "Function and chemistry"
},
{
"paragraph_id": 150,
"text": "Alternatively, glucose monomers in the chloroplast can be linked together to make starch, which accumulates into the starch grains found in the chloroplast. Under conditions such as high atmospheric CO2 concentrations, these starch grains may grow very large, distorting the grana and thylakoids. The starch granules displace the thylakoids, but leave them intact. Waterlogged roots can also cause starch buildup in the chloroplasts, possibly due to less sucrose being exported out of the chloroplast (or more accurately, the plant cell). This depletes a plant's free phosphate supply, which indirectly stimulates chloroplast starch synthesis. While linked to low photosynthesis rates, the starch grains themselves may not necessarily interfere significantly with the efficiency of photosynthesis, and might simply be a side effect of another photosynthesis-depressing factor.",
"title": "Function and chemistry"
},
{
"paragraph_id": 151,
"text": "Photorespiration can occur when the oxygen concentration is too high. RuBisCO cannot distinguish between oxygen and carbon dioxide very well, so it can accidentally add O2 instead of CO2 to RuBP. This process reduces the efficiency of photosynthesis—it consumes ATP and oxygen, releases CO2, and produces no sugar. It can waste up to half the carbon fixed by the Calvin cycle. Several mechanisms have evolved in different lineages that raise the carbon dioxide concentration relative to oxygen within the chloroplast, increasing the efficiency of photosynthesis. These mechanisms are called carbon dioxide concentrating mechanisms, or CCMs. These include Crassulacean acid metabolism, C4 carbon fixation, and pyrenoids. Chloroplasts in C4 plants are notable as they exhibit a distinct chloroplast dimorphism.",
"title": "Function and chemistry"
},
{
"paragraph_id": 152,
"text": "Because of the H gradient across the thylakoid membrane, the interior of the thylakoid is acidic, with a pH around 4, while the stroma is slightly basic, with a pH of around 8. The optimal stroma pH for the Calvin cycle is 8.1, with the reaction nearly stopping when the pH falls below 7.3.",
"title": "Function and chemistry"
},
{
"paragraph_id": 153,
"text": "CO2 in water can form carbonic acid, which can disturb the pH of isolated chloroplasts, interfering with photosynthesis, even though CO2 is used in photosynthesis. However, chloroplasts in living plant cells are not affected by this as much.",
"title": "Function and chemistry"
},
{
"paragraph_id": 154,
"text": "Chloroplasts can pump K and H ions in and out of themselves using a poorly understood light-driven transport system.",
"title": "Function and chemistry"
},
{
"paragraph_id": 155,
"text": "In the presence of light, the pH of the thylakoid lumen can drop up to 1.5 pH units, while the pH of the stroma can rise by nearly one pH unit.",
"title": "Function and chemistry"
},
{
"paragraph_id": 156,
"text": "Chloroplasts alone make almost all of a plant cell's amino acids in their stroma except the sulfur-containing ones like cysteine and methionine. Cysteine is made in the chloroplast (the proplastid too) but it is also synthesized in the cytosol and mitochondria, probably because it has trouble crossing membranes to get to where it is needed. The chloroplast is known to make the precursors to methionine but it is unclear whether the organelle carries out the last leg of the pathway or if it happens in the cytosol.",
"title": "Function and chemistry"
},
{
"paragraph_id": 157,
"text": "Chloroplasts make all of a cell's purines and pyrimidines—the nitrogenous bases found in DNA and RNA. They also convert nitrite (NO2) into ammonia (NH3) which supplies the plant with nitrogen to make its amino acids and nucleotides.",
"title": "Function and chemistry"
},
{
"paragraph_id": 158,
"text": "The plastid is the site of diverse and complex lipid synthesis in plants. The carbon used to form the majority of the lipid is from acetyl-CoA, which is the decarboxylation product of pyruvate. Pyruvate may enter the plastid from the cytosol by passive diffusion through the membrane after production in glycolysis. Pyruvate is also made in the plastid from phosphoenolpyruvate, a metabolite made in the cytosol from pyruvate or PGA. Acetate in the cytosol is unavailable for lipid biosynthesis in the plastid. The typical length of fatty acids produced in the plastid are 16 or 18 carbons, with 0-3 cis double bonds.",
"title": "Function and chemistry"
},
{
"paragraph_id": 159,
"text": "The biosynthesis of fatty acids from acetyl-CoA primarily requires two enzymes. Acetyl-CoA carboxylase creates malonyl-CoA, used in both the first step and the extension steps of synthesis. Fatty acid synthase (FAS) is a large complex of enzymes and cofactors including acyl carrier protein (ACP) which holds the acyl chain as it is synthesized. The initiation of synthesis begins with the condensation of malonyl-ACP with acetyl-CoA to produce ketobutyryl-ACP. 2 reductions involving the use of NADPH and one dehydration creates butyryl-ACP. Extension of the fatty acid comes from repeated cycles of malonyl-ACP condensation, reduction, and dehydration.",
"title": "Function and chemistry"
},
{
"paragraph_id": 160,
"text": "Other lipids are derived from the methyl-erythritol phosphate (MEP) pathway and consist of gibberelins, sterols, abscisic acid, phytol, and innumerable secondary metabolites.",
"title": "Function and chemistry"
},
{
"paragraph_id": 161,
"text": "Chloroplasts are a special type of a plant cell organelle called a plastid, though the two terms are sometimes used interchangeably. There are many other types of plastids, which carry out various functions. All chloroplasts in a plant are descended from undifferentiated proplastids found in the zygote, or fertilized egg. Proplastids are commonly found in an adult plant's apical meristems. Chloroplasts do not normally develop from proplastids in root tip meristems—instead, the formation of starch-storing amyloplasts is more common.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 162,
"text": "In shoots, proplastids from shoot apical meristems can gradually develop into chloroplasts in photosynthetic leaf tissues as the leaf matures, if exposed to the required light. This process involves invaginations of the inner plastid membrane, forming sheets of membrane that project into the internal stroma. These membrane sheets then fold to form thylakoids and grana.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 163,
"text": "If angiosperm shoots are not exposed to the required light for chloroplast formation, proplastids may develop into an etioplast stage before becoming chloroplasts. An etioplast is a plastid that lacks chlorophyll, and has inner membrane invaginations that form a lattice of tubes in their stroma, called a prolamellar body. While etioplasts lack chlorophyll, they have a yellow chlorophyll precursor stocked. Within a few minutes of light exposure, the prolamellar body begins to reorganize into stacks of thylakoids, and chlorophyll starts to be produced. This process, where the etioplast becomes a chloroplast, takes several hours. Gymnosperms do not require light to form chloroplasts.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 164,
"text": "Light, however, does not guarantee that a proplastid will develop into a chloroplast. Whether a proplastid develops into a chloroplast some other kind of plastid is mostly controlled by the nucleus and is largely influenced by the kind of cell it resides in.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 165,
"text": "Plastid differentiation is not permanent, in fact many interconversions are possible. Chloroplasts may be converted to chromoplasts, which are pigment-filled plastids responsible for the bright colors seen in flowers and ripe fruit. Starch storing amyloplasts can also be converted to chromoplasts, and it is possible for proplastids to develop straight into chromoplasts. Chromoplasts and amyloplasts can also become chloroplasts, like what happens when a carrot or a potato is illuminated. If a plant is injured, or something else causes a plant cell to revert to a meristematic state, chloroplasts and other plastids can turn back into proplastids. Chloroplast, amyloplast, chromoplast, proplastid are not absolute; state—intermediate forms are common.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 166,
"text": "Most chloroplasts in a photosynthetic cell do not develop directly from proplastids or etioplasts. In fact, a typical shoot meristematic plant cell contains only 7–20 proplastids. These proplastids differentiate into chloroplasts, which divide to create the 30–70 chloroplasts found in a mature photosynthetic plant cell. If the cell divides, chloroplast division provides the additional chloroplasts to partition between the two daughter cells.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 167,
"text": "In single-celled algae, chloroplast division is the only way new chloroplasts are formed. There is no proplastid differentiation—when an algal cell divides, its chloroplast divides along with it, and each daughter cell receives a mature chloroplast.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 168,
"text": "Almost all chloroplasts in a cell divide, rather than a small group of rapidly dividing chloroplasts. Chloroplasts have no definite S-phase—their DNA replication is not synchronized or limited to that of their host cells. Much of what we know about chloroplast division comes from studying organisms like Arabidopsis and the red alga Cyanidioschyzon merolæ.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 169,
"text": "The division process starts when the proteins FtsZ1 and FtsZ2 assemble into filaments, and with the help of a protein ARC6, form a structure called a Z-ring within the chloroplast's stroma. The Min system manages the placement of the Z-ring, ensuring that the chloroplast is cleaved more or less evenly. The protein MinD prevents FtsZ from linking up and forming filaments. Another protein ARC3 may also be involved, but it is not very well understood. These proteins are active at the poles of the chloroplast, preventing Z-ring formation there, but near the center of the chloroplast, MinE inhibits them, allowing the Z-ring to form.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 170,
"text": "Next, the two plastid-dividing rings, or PD rings form. The inner plastid-dividing ring is located in the inner side of the chloroplast's inner membrane, and is formed first. The outer plastid-dividing ring is found wrapped around the outer chloroplast membrane. It consists of filaments about 5 nanometers across, arranged in rows 6.4 nanometers apart, and shrinks to squeeze the chloroplast. This is when chloroplast constriction begins. In a few species like Cyanidioschyzon merolæ, chloroplasts have a third plastid-dividing ring located in the chloroplast's intermembrane space.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 171,
"text": "Late into the constriction phase, dynamin proteins assemble around the outer plastid-dividing ring, helping provide force to squeeze the chloroplast. Meanwhile, the Z-ring and the inner plastid-dividing ring break down. During this stage, the many chloroplast DNA plasmids floating around in the stroma are partitioned and distributed to the two forming daughter chloroplasts.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 172,
"text": "Later, the dynamins migrate under the outer plastid dividing ring, into direct contact with the chloroplast's outer membrane, to cleave the chloroplast in two daughter chloroplasts.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 173,
"text": "A remnant of the outer plastid dividing ring remains floating between the two daughter chloroplasts, and a remnant of the dynamin ring remains attached to one of the daughter chloroplasts.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 174,
"text": "Of the five or six rings involved in chloroplast division, only the outer plastid-dividing ring is present for the entire constriction and division phase—while the Z-ring forms first, constriction does not begin until the outer plastid-dividing ring forms.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 175,
"text": "In species of algae that contain a single chloroplast, regulation of chloroplast division is extremely important to ensure that each daughter cell receives a chloroplast—chloroplasts can't be made from scratch. In organisms like plants, whose cells contain multiple chloroplasts, coordination is looser and less important. It is likely that chloroplast and cell division are somewhat synchronized, though the mechanisms for it are mostly unknown.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 176,
"text": "Light has been shown to be a requirement for chloroplast division. Chloroplasts can grow and progress through some of the constriction stages under poor quality green light, but are slow to complete division—they require exposure to bright white light to complete division. Spinach leaves grown under green light have been observed to contain many large dumbbell-shaped chloroplasts. Exposure to white light can stimulate these chloroplasts to divide and reduce the population of dumbbell-shaped chloroplasts.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 177,
"text": "Like mitochondria, chloroplasts are usually inherited from a single parent. Biparental chloroplast inheritance—where plastid genes are inherited from both parent plants—occurs in very low levels in some flowering plants.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 178,
"text": "Many mechanisms prevent biparental chloroplast DNA inheritance, including selective destruction of chloroplasts or their genes within the gamete or zygote, and chloroplasts from one parent being excluded from the embryo. Parental chloroplasts can be sorted so that only one type is present in each offspring.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 179,
"text": "Gymnosperms, such as pine trees, mostly pass on chloroplasts paternally, while flowering plants often inherit chloroplasts maternally. Flowering plants were once thought to only inherit chloroplasts maternally. However, there are now many documented cases of angiosperms inheriting chloroplasts paternally.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 180,
"text": "Angiosperms, which pass on chloroplasts maternally, have many ways to prevent paternal inheritance. Most of them produce sperm cells that do not contain any plastids. There are many other documented mechanisms that prevent paternal inheritance in these flowering plants, such as different rates of chloroplast replication within the embryo.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 181,
"text": "Among angiosperms, paternal chloroplast inheritance is observed more often in hybrids than in offspring from parents of the same species. This suggests that incompatible hybrid genes might interfere with the mechanisms that prevent paternal inheritance.",
"title": "Differentiation, replication, and inheritance"
},
{
"paragraph_id": 182,
"text": "Recently, chloroplasts have caught attention by developers of genetically modified crops. Since, in most flowering plants, chloroplasts are not inherited from the male parent, transgenes in these plastids cannot be disseminated by pollen. This makes plastid transformation a valuable tool for the creation and cultivation of genetically modified plants that are biologically contained, thus posing significantly lower environmental risks. This biological containment strategy is therefore suitable for establishing the coexistence of conventional and organic agriculture. While the reliability of this mechanism has not yet been studied for all relevant crop species, recent results in tobacco plants are promising, showing a failed containment rate of transplastomic plants at 3 in 1,000,000.",
"title": "Differentiation, replication, and inheritance"
}
] | A chloroplast is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water in the cells. The ATP and NADPH is then used to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from one, in unicellular algae, up to 100 in plants like Arabidopsis and wheat. A chloroplast is characterized by its two membranes and a high concentration of chlorophyll. Other plastid types, such as the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photosynthesis. Chloroplasts are highly dynamic—they circulate and are moved around within plant cells, and occasionally pinch in two to reproduce. Their behavior is strongly influenced by environmental factors like light color and intensity. Chloroplasts, like mitochondria, contain their own DNA, which is thought to be inherited from their ancestor—a photosynthetic cyanobacterium that was engulfed by an early eukaryotic cell. Chloroplasts cannot be made by the plant cell and must be inherited by each daughter cell during cell division. With one exception, all chloroplasts can probably be traced back to a single endosymbiotic event, when a cyanobacterium was engulfed by the eukaryote. Despite this, chloroplasts can be found in an extremely wide set of organisms, some not even directly related to each other—a consequence of many secondary and even tertiary endosymbiotic events. The word chloroplast is derived from the Greek words chloros (χλωρός), which means green, and plastes (πλάστης), which means "the one who forms". | 2001-09-25T20:54:53Z | 2023-11-21T08:58:45Z | [
"Template:C4",
"Template:Cite web",
"Template:Short description",
"Template:See also",
"Template:Chloroplast cladograms are complicated",
"Template:Main",
"Template:Clear",
"Template:Cite thesis",
"Template:Authority control",
"Template:Pp-move",
"Template:Use dmy dates",
"Template:Refn",
"Template:Dubious",
"Template:Commons category",
"Template:CO2",
"Template:Cite journal",
"Template:Pp-semi-indef",
"Template:TOC limit",
"Template:Chloroplast DNA",
"Template:C3",
"Template:Organelles",
"Template:Self-replicating organic structures",
"Template:Cite magazine",
"Template:Page needed",
"Template:Plain image with caption",
"Template:IPAc-en",
"Template:Cite book",
"Template:Reflist",
"Template:Botany",
"Template:Sub",
"Template:Expand section",
"Template:Sup",
"Template:Cite encyclopedia"
] | https://en.wikipedia.org/wiki/Chloroplast |
6,357 | Camp David | Camp David is a 125-acre (51 ha) country retreat for the President of the United States. It is located in the wooded hills of Catoctin Mountain Park, in Frederick County, Maryland, near the towns of Thurmont and Emmitsburg, about 62 miles (100 km) north-northwest of the national capital city of Washington, D.C. It is code named Naval Support Facility Thurmont. Technically a military installation, its staffing is primarily provided by the Seabees, Civil Engineer Corps (CEC), the United States Navy and the United States Marine Corps. Naval construction battalions are tasked with Camp David construction and send detachments as needed.
Originally known as Hi-Catoctin, Camp David was built as a retreat for federal government agents and their families by the Works Progress Administration. Construction started in 1935 and was completed in 1938. In 1942, President Franklin D. Roosevelt converted it to a presidential retreat and renamed it "Shangri-La", after the fictional Himalayan paradise. Camp David received its present name in 1953 from President Dwight D. Eisenhower, in honor of his father and his grandson, both named David.
The Catoctin Mountain Park does not indicate the location of Camp David on park maps due to privacy and security concerns, although it can be seen through the use of publicly accessible satellite images.
Camp David has been used to host private diplomatic meetings with foreign leaders and heads of state since at least World War II. Franklin D. Roosevelt hosted Sir Winston Churchill at Shangri-La in May 1943, during World War II. Dwight Eisenhower held his first cabinet meeting there on November 22, 1955, following hospitalization and convalescence he required after a heart attack suffered in Denver, Colorado, on September 24. Eisenhower met Nikita Khrushchev there for two days of discussions in September 1959.
John F. Kennedy and his family often enjoyed riding and other recreational activities there, and Kennedy often allowed White House staff and Cabinet members to use the retreat when he or his family were not there. Lyndon B. Johnson met with advisors in this setting and hosted both Australian prime minister Harold Holt and Canadian prime minister Lester B. Pearson there. Richard Nixon was a frequent visitor. He personally directed the construction of a swimming pool and other improvements to Aspen Lodge. Gerald Ford hosted Indonesian president Suharto at Camp David.
Jimmy Carter initially favored closing Camp David in order to save money, but once he visited the retreat, he decided to keep it. Carter brokered the Camp David Accords there in September 1978 between Egyptian president Anwar al-Sadat and Israeli prime minister Menachem Begin. Ronald Reagan visited the retreat more than any other president. In 1984, Reagan hosted British prime minister Margaret Thatcher. Reagan restored the nature trails that Nixon paved over so he could horseback ride at Camp David. George H. W. Bush's daughter, Dorothy Bush Koch, was married there in 1992, in the first wedding held at Camp David. During his tenure as president, Bill Clinton spent every Thanksgiving at Camp David with his family. In July 2000, he hosted the 2000 Camp David Summit negotiations between Israeli prime minister Ehud Barak and Palestinian Authority chairman Yasser Arafat there.
In February 2001, George W. Bush held his first meeting with a European leader, UK prime minister Tony Blair, at Camp David, to discuss missile defense, Iraq, and NATO. After the September 11 attacks, Bush held a Cabinet meeting at Camp David to prepare the United States invasion of Afghanistan. During his two terms in office, Bush visited Camp David 149 times, for a total of 487 days, for hosting foreign visitors as well as a personal retreat. He met Blair there four times. Among the numerous other foreign leaders he hosted at Camp David were Russian president Vladimir Putin and President Musharraf of Pakistan in 2003, Danish prime minister Anders Fogh Rasmussen in June 2006, and British prime minister Gordon Brown in 2007.
Barack Obama chose Camp David to host the 38th G8 summit in 2012. President Obama also hosted Russian prime minister Dmitry Medvedev at Camp David, as well as the GCC Summit there in 2015.
Donald Trump hosted Senate majority leader Mitch McConnell and Speaker of the House Paul Ryan at Camp David while the Republican Party prepared to defend both houses of Congress in the 2018 midterm elections. The 46th G7 summit was to be held at Camp David on June 10–12, 2020, but was cancelled due to health concerns during the ongoing COVID-19 pandemic.
Joe Biden hosted the U.S.–Japan–Korea Summit with Japanese Prime Minister Fumio Kishida and South Korean President Yoon Suk Yeol at Camp David in August 2023, resulting declaration of Camp David Principles on trilateral relationship among U.S., Japan and South Korea.
To be able to play his favorite sport, President Eisenhower had golf course architect Robert Trent Jones design a practice golf facility at Camp David. Around 1954, Jones built one golf hole—a par 3—with four different tees; Eisenhower added a 250-yard (230 m) driving range near the helicopter landing zone.
On July 2, 2011, an F-15 intercepted a civilian aircraft approximately 6 miles (10 km) from Camp David, when President Obama was in the residence. The two-seater, which was out of radio communication, was escorted to nearby Hagerstown, Maryland, without incident.
On July 10, 2011, an F-15 intercepted another small plane near Camp David when Obama was again in the residence; a total of three were intercepted that weekend. | [
{
"paragraph_id": 0,
"text": "Camp David is a 125-acre (51 ha) country retreat for the President of the United States. It is located in the wooded hills of Catoctin Mountain Park, in Frederick County, Maryland, near the towns of Thurmont and Emmitsburg, about 62 miles (100 km) north-northwest of the national capital city of Washington, D.C. It is code named Naval Support Facility Thurmont. Technically a military installation, its staffing is primarily provided by the Seabees, Civil Engineer Corps (CEC), the United States Navy and the United States Marine Corps. Naval construction battalions are tasked with Camp David construction and send detachments as needed.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Originally known as Hi-Catoctin, Camp David was built as a retreat for federal government agents and their families by the Works Progress Administration. Construction started in 1935 and was completed in 1938. In 1942, President Franklin D. Roosevelt converted it to a presidential retreat and renamed it \"Shangri-La\", after the fictional Himalayan paradise. Camp David received its present name in 1953 from President Dwight D. Eisenhower, in honor of his father and his grandson, both named David.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The Catoctin Mountain Park does not indicate the location of Camp David on park maps due to privacy and security concerns, although it can be seen through the use of publicly accessible satellite images.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Camp David has been used to host private diplomatic meetings with foreign leaders and heads of state since at least World War II. Franklin D. Roosevelt hosted Sir Winston Churchill at Shangri-La in May 1943, during World War II. Dwight Eisenhower held his first cabinet meeting there on November 22, 1955, following hospitalization and convalescence he required after a heart attack suffered in Denver, Colorado, on September 24. Eisenhower met Nikita Khrushchev there for two days of discussions in September 1959.",
"title": "Presidential use"
},
{
"paragraph_id": 4,
"text": "John F. Kennedy and his family often enjoyed riding and other recreational activities there, and Kennedy often allowed White House staff and Cabinet members to use the retreat when he or his family were not there. Lyndon B. Johnson met with advisors in this setting and hosted both Australian prime minister Harold Holt and Canadian prime minister Lester B. Pearson there. Richard Nixon was a frequent visitor. He personally directed the construction of a swimming pool and other improvements to Aspen Lodge. Gerald Ford hosted Indonesian president Suharto at Camp David.",
"title": "Presidential use"
},
{
"paragraph_id": 5,
"text": "Jimmy Carter initially favored closing Camp David in order to save money, but once he visited the retreat, he decided to keep it. Carter brokered the Camp David Accords there in September 1978 between Egyptian president Anwar al-Sadat and Israeli prime minister Menachem Begin. Ronald Reagan visited the retreat more than any other president. In 1984, Reagan hosted British prime minister Margaret Thatcher. Reagan restored the nature trails that Nixon paved over so he could horseback ride at Camp David. George H. W. Bush's daughter, Dorothy Bush Koch, was married there in 1992, in the first wedding held at Camp David. During his tenure as president, Bill Clinton spent every Thanksgiving at Camp David with his family. In July 2000, he hosted the 2000 Camp David Summit negotiations between Israeli prime minister Ehud Barak and Palestinian Authority chairman Yasser Arafat there.",
"title": "Presidential use"
},
{
"paragraph_id": 6,
"text": "In February 2001, George W. Bush held his first meeting with a European leader, UK prime minister Tony Blair, at Camp David, to discuss missile defense, Iraq, and NATO. After the September 11 attacks, Bush held a Cabinet meeting at Camp David to prepare the United States invasion of Afghanistan. During his two terms in office, Bush visited Camp David 149 times, for a total of 487 days, for hosting foreign visitors as well as a personal retreat. He met Blair there four times. Among the numerous other foreign leaders he hosted at Camp David were Russian president Vladimir Putin and President Musharraf of Pakistan in 2003, Danish prime minister Anders Fogh Rasmussen in June 2006, and British prime minister Gordon Brown in 2007.",
"title": "Presidential use"
},
{
"paragraph_id": 7,
"text": "Barack Obama chose Camp David to host the 38th G8 summit in 2012. President Obama also hosted Russian prime minister Dmitry Medvedev at Camp David, as well as the GCC Summit there in 2015.",
"title": "Presidential use"
},
{
"paragraph_id": 8,
"text": "Donald Trump hosted Senate majority leader Mitch McConnell and Speaker of the House Paul Ryan at Camp David while the Republican Party prepared to defend both houses of Congress in the 2018 midterm elections. The 46th G7 summit was to be held at Camp David on June 10–12, 2020, but was cancelled due to health concerns during the ongoing COVID-19 pandemic.",
"title": "Presidential use"
},
{
"paragraph_id": 9,
"text": "Joe Biden hosted the U.S.–Japan–Korea Summit with Japanese Prime Minister Fumio Kishida and South Korean President Yoon Suk Yeol at Camp David in August 2023, resulting declaration of Camp David Principles on trilateral relationship among U.S., Japan and South Korea.",
"title": "Presidential use"
},
{
"paragraph_id": 10,
"text": "To be able to play his favorite sport, President Eisenhower had golf course architect Robert Trent Jones design a practice golf facility at Camp David. Around 1954, Jones built one golf hole—a par 3—with four different tees; Eisenhower added a 250-yard (230 m) driving range near the helicopter landing zone.",
"title": "Practice golf facility"
},
{
"paragraph_id": 11,
"text": "On July 2, 2011, an F-15 intercepted a civilian aircraft approximately 6 miles (10 km) from Camp David, when President Obama was in the residence. The two-seater, which was out of radio communication, was escorted to nearby Hagerstown, Maryland, without incident.",
"title": "Security incidents"
},
{
"paragraph_id": 12,
"text": "On July 10, 2011, an F-15 intercepted another small plane near Camp David when Obama was again in the residence; a total of three were intercepted that weekend.",
"title": "Security incidents"
}
] | Camp David is a 125-acre (51 ha) country retreat for the President of the United States. It is located in the wooded hills of Catoctin Mountain Park, in Frederick County, Maryland, near the towns of Thurmont and Emmitsburg, about 62 miles (100 km) north-northwest of the national capital city of Washington, D.C. It is code named Naval Support Facility Thurmont. Technically a military installation, its staffing is primarily provided by the Seabees, Civil Engineer Corps (CEC), the United States Navy and the United States Marine Corps. Naval construction battalions are tasked with Camp David construction and send detachments as needed. Originally known as Hi-Catoctin, Camp David was built as a retreat for federal government agents and their families by the Works Progress Administration. Construction started in 1935 and was completed in 1938. In 1942, President Franklin D. Roosevelt converted it to a presidential retreat and renamed it "Shangri-La", after the fictional Himalayan paradise. Camp David received its present name in 1953 from President Dwight D. Eisenhower, in honor of his father and his grandson, both named David. The Catoctin Mountain Park does not indicate the location of Camp David on park maps due to privacy and security concerns, although it can be seen through the use of publicly accessible satellite images. | 2001-10-15T04:01:53Z | 2023-12-23T17:01:35Z | [
"Template:Commons category",
"Template:Authority control",
"Template:Convert",
"Template:Sfn",
"Template:Cbignore",
"Template:Infobox military installation",
"Template:Webarchive",
"Template:Cite book",
"Template:Cite news",
"Template:White House Military Office",
"Template:Short description",
"Template:About",
"Template:Use mdy dates",
"Template:Official Government residences in North America and the Caribbean",
"Template:Refbegin",
"Template:Clear",
"Template:Portal",
"Template:Reflist",
"Template:Refend",
"Template:Official website",
"Template:Nbsp",
"Template:Cite web",
"Template:Dead link"
] | https://en.wikipedia.org/wiki/Camp_David |
6,359 | Crux | Crux (/krʌks/) is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross. It lies on the southern end of the Milky Way's visible band. The name Crux is Latin for cross. Even though it is the smallest of all 88 modern constellations, Crux is among the most easily distinguished as its four main stars each have an apparent visual magnitude brighter than +2.8. It has attained a high level of cultural significance in many Southern Hemisphere states and nations.
Blue-white α Crucis (Acrux) is the most southerly member of the constellation and, at magnitude 0.8, the brightest. The three other stars of the cross appear clockwise and in order of lessening magnitude: β Crucis (Mimosa), γ Crucis (Gacrux), and δ Crucis (Imai). ε Crucis (Ginan) also lies within the cross asterism. Many of these brighter stars are members of the Scorpius–Centaurus association, a large but loose group of hot blue-white stars that appear to share common origins and motion across the southern Milky Way.
Crux contains four Cepheid variables, each visible to the naked eye under optimum conditions. Crux also contains the bright and colourful open cluster known as the Jewel Box (NGC 4755) on its eastern border. Nearby to the southeast is a large dark nebula spanning 7° by 5° known as the Coalsack Nebula, portions of which are mapped in the neighbouring constellations of Centaurus and Musca.
The bright stars in Crux were known to the Ancient Greeks, where Ptolemy regarded them as part of the constellation Centaurus. They were entirely visible as far north as Britain in the fourth millennium BC. However, the precession of the equinoxes gradually lowered the stars below the European horizon, and they were eventually forgotten by the inhabitants of northern latitudes. By 400 AD, the stars in the constellation now called Crux never rose above the horizon throughout most of Europe. Dante may have known about the constellation in the 14th century, as he describes an asterism of four bright stars in the southern sky in his Divine Comedy. His description, however, may be allegorical, and the similarity to the constellation a coincidence.
The 15th century Venetian navigator Alvise Cadamosto made note of what was probably the Southern Cross on exiting the Gambia River in 1455, calling it the carro dell'ostro ("southern chariot"). However, Cadamosto's accompanying diagram was inaccurate. Historians generally credit João Faras for being the first European to depict it correctly. Faras sketched and described the constellation (calling it "las guardas") in a letter written on the beaches of Brazil on 1 May 1500 to the Portuguese monarch.
Explorer Amerigo Vespucci seems to have observed not only the Southern Cross but also the neighboring Coalsack Nebula on his second voyage in 1501–1502.
Another early modern description clearly describing Crux as a separate constellation is attributed to Andrea Corsali, an Italian navigator who from 1515–1517 sailed to China and the East Indies in an expedition sponsored by King Manuel I. In 1516, Corsali wrote a letter to the monarch describing his observations of the southern sky, which included a rather crude map of the stars around the south celestial pole including the Southern Cross and the two Magellanic Clouds seen in an external orientation, as on a globe.
Emery Molyneux and Petrus Plancius have also been cited as the first uranographers (sky mappers) to distinguish Crux as a separate constellation; their representations date from 1592, the former depicting it on his celestial globe and the latter in one of the small celestial maps on his large wall map. Both authors, however, depended on unreliable sources and placed Crux in the wrong position. Crux was first shown in its correct position on the celestial globes of Petrus Plancius and Jodocus Hondius in 1598 and 1600. Its stars were first catalogued separately from Centaurus by Frederick de Houtman in 1603. The constellation was later adopted by Jakob Bartsch in 1624 and Augustin Royer in 1679. Royer is sometimes wrongly cited as initially distinguishing Crux.
Crux is bordered by the constellations Centaurus (which surrounds it on three sides) on the east, north and west, and Musca to the south. Covering 68 square degrees and 0.165% of the night sky, it is the smallest of the 88 constellations. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Cru". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of four segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 11 56.13 and 12 57.45 , while the declination coordinates are between −55.68° and −64.70°. Its totality figures at least part of the year south of the 25th parallel north.
In tropical regions Crux can be seen in the sky from April to June. Crux is exactly opposite to Cassiopeia on the celestial sphere, and therefore it cannot appear in the sky with the latter at the same time. In this era, south of Cape Town, Adelaide, and Buenos Aires (the 34th parallel south), Crux is circumpolar and thus always appears in the sky.
Crux is sometimes confused with the nearby False Cross asterism by stargazers. The False Cross consists of stars in Carina and Vela, is larger and dimmer, does not have a fifth star, and lacks the two prominent nearby "Pointer Stars". Between the two is the even larger and dimmer Diamond Cross.
Crux is easily visible from the southern hemisphere, south of 35th parallel at practically any time of year as circumpolar. It is also visible near the horizon from tropical latitudes of the northern hemisphere for a few hours every night during the northern winter and spring. For instance, it is visible from Cancun or any other place at latitude 25° N or less at around 10 pm at the end of April. There are 5 main stars. Due to precession, Crux will move closer to the South Pole in the next millennia, up to 67 degrees south declination for the middle of the constellation. However, by the year 14,000 Crux will be visible for most parts of Europe and continental United States which will extend to North Europe by the year 18,000 as it will be less than 30 degrees south declination.
In the Southern Hemisphere, the Southern Cross is frequently used for navigation in much the same way that Polaris is used in the Northern Hemisphere. Projecting a line from γ to α Crucis (the foot of the crucifix) approximately 4+1⁄2 times beyond gives a point close to the Southern Celestial Pole which is also, coincidentally, where intersects a perpendicular line taken southwards from the east-west axis of Alpha Centauri to Beta Centauri, which are stars at an alike declination to Crux and of a similar width as the cross, but higher magnitude. Argentine gauchos are documented as using Crux for night orientation in the Pampas and Patagonia.
Alpha and Beta Centauri are of similar declinations (thus distance from the pole) and are often referred as the "Southern Pointers" or just "The Pointers", allowing people to easily identify the Southern Cross, the constellation of Crux. Very few bright stars lie between Crux and the pole itself, although the constellation Musca is fairly easily recognised immediately south of Crux.
Down to apparent magnitude +2.5 are 92 stars that shine the brightest as viewed from the Earth. Three of these stars are in Crux making it the most densely populated as to those stars (this being 3.26% of these 92 stars, and in turn being 19.2 times more than the expected 0.17% that would result on a homogenous distribution of all bright stars and a randomised drawing of all 88 constellations, given its area, 0.17% of the sky).
Within the constellation's borders, there are 49 stars brighter than or equal to apparent magnitude 6.5. The four main stars that form the asterism are Alpha, Beta, Gamma, and Delta Crucis.
There is also a fifth star, that is often included with the Southern Cross.
There are several other naked-eye stars within the borders of Crux, especially:
Unusually, a total of 15 of the 23 brightest stars in Crux are spectrally blue-white B-type stars. Among the five main bright stars, Delta, and probably Alpha and Beta, are likely co-moving B-type members of the Scorpius–Centaurus association, the nearest OB association to the Sun. They are among the highest-mass stellar members of the Lower Centaurus–Crux subgroup of the association, with ages of roughly 10 to 20 million years. Other members include the blue-white stars Zeta, Lambda and both the components of the visual double star, Mu.
Crux contains many variable stars. It boasts four Cepheid variables that may all reach naked eye visibility.
Other well studied variable stars includes:
The star HD 106906 has been found to have a planet—HD 106906 b—that has one of the widest orbits of any currently known planetary-mass companions.
Crux is backlit by the multitude of stars of the Scutum-Crux Arm (more commonly called the Scutum-Centaurus Arm) of the Milky Way. This is the main inner arm in the local radial quarter of the galaxy. Part-obscuring this is:
A key feature of the Scutum-Crux Arm is:
The most prominent feature of Crux is the distinctive asterism known as the Southern Cross. It has great significance in the cultures of the southern hemisphere, particularly of Australia, Brazil, Chile and New Zealand.
Several southern countries and organisations have traditionally used Crux as a national or distinctive symbol. The four or five brightest stars of Crux appear, heraldically standardised in various ways, on the flags of Australia, Brazil, New Zealand, Papua New Guinea and Samoa. They also appear on the flags of the Australian state of Victoria, the Australian Capital Territory, the Northern Territory, as well as the flag of Magallanes Region of Chile, the flag of Londrina (Brazil) and several Argentine provincial flags and emblems (for example, Tierra del Fuego and Santa Cruz). The flag of the Mercosur trading zone displays the four brightest stars. Crux also appears on the Brazilian coat of arms and, as of July 2015, on the cover of Brazilian passports.
Five stars appear in the logo of the Brazilian football team Cruzeiro Esporte Clube and in the insignia of the Order of the Southern Cross, and the cross has featured as name of the Brazilian currency (the cruzeiro from 1942 to 1986 and again from 1990 to 1994). All coins of the current (1998) series of the Brazilian real display the constellation.
Songs and literature reference the Southern Cross, including the Argentine epic poem Martín Fierro. The Argentinian singer Charly García says that he is "from the Southern Cross" in the song "No voy en tren".
The Cross gets a mention in the lyrics of the Brazilian National Anthem (1909): "A imagem do Cruzeiro resplandece" ("the image of the Cross shines").
The Southern Cross is mentioned in the Australian National Anthem, "Beneath our radiant Southern Cross we'll toil with hearts and hands"
The Southern Cross features in the coat of arms of William Birdwood, 1st Baron Birdwood, the British officer who commanded the Australian and New Zealand Army Corps during the Gallipoli Campaign of the First World War.
The Southern Cross is also mentioned in the Samoan National Anthem. "Vaai 'i na fetu o lo'u a agiagia ai: Le faailoga lea o Iesu, na maliu ai mo Samoa." ("Look at those stars that are waving on it: This is the symbol of Jesus, who died on it for Samoa.")
The 1952-53 NBC Television Series Victory At Sea contained a musical number entitled "Beneath the Southern Cross".
"Southern Cross" is a single released by Crosby, Stills and Nash in 1981. It reached #18 on Billboard Hot 100 in late 1982.
"The Sign of the Southern Cross" is a song released by Black Sabbath in 1981. The song was released on the album "Mob Rules".
The Order of the Southern Cross is a Brazilian order of chivalry awarded to "those who have rendered significant service to the Brazilian nation".
In "O Sweet Saint Martin's Land", the lyrics mention the Southern Cross: Thy Southern Cross the night.
A stylized version of Crux appears on the Australian Eureka Flag. The constellation was also used on the dark blue, shield-like patch worn by personnel of the U.S. Army's Americal Division, which was organized in the Southern Hemisphere, on the island of New Caledonia, and also on the blue diamond of the U.S. 1st Marine Division, which fought on the Southern Hemisphere islands of Guadalcanal and New Britain.
The Petersflagge flag of the German East Africa Company of 1885–1920, which included a constellation of five white five-pointed Crux "stars" on a red ground, later served as the model for symbolism associated with generic German colonial-oriented organisations: the Reichskolonialbund of 1936–1943 and the Friends of the former German Protectorates [de] (1956/1983 to the present).
Southern Cross station is a major rail terminal in Melbourne, Australia.
The Personal Ordinariate of Our Lady of the Southern Cross is a personal ordinariate of the Roman Catholic Church primarily within the territory of the Australian Catholic Bishops Conference for groups of Anglicans who desire full communion with the Catholic Church in Australia and Asia.
The Knights of the Southern Cross (KSC) is a Catholic fraternal order throughout Australia.
In India, there is a story related to the creation of Trishanku Swarga (त्रिशंकु), meaning Cross (Crux), created by Sage Vishwamitra.
In Chinese, 十字架 (Shí Zì Jià), meaning Cross, refers to an asterism consisting of γ Crucis, α Crucis, β Crucis and δ Crucis.
In Australian Aboriginal astronomy, Crux and the Coalsack mark the head of the 'Emu in the Sky' (which is seen in the dark spaces rather than in the patterns of stars) in several Aboriginal cultures, while Crux itself is said to be a possum sitting in a tree (Boorong people of the Wimmera region of northwestern Victoria), a representation of the sky deity Mirrabooka (Quandamooka people of Stradbroke Island), a stingray (Yolngu people of Arnhem Land), or an eagle (Kaurna people of the Adelaide Plains). Two Pacific constellations also included Gamma Centauri. Torres Strait Islanders in modern-day Australia saw Gamma Centauri as the handle and the four stars as the left hand of Tagai, and the stars of Musca as the trident of the fishing spear he is holding. In Aranda traditions of central Australia, the four Cross stars are the talon of an eagle and Gamma Centauri as its leg.
Various peoples in the East Indies and Brazil viewed the four main stars as the body of a ray. In both Indonesia and Malaysia, it is known as Bintang Pari and Buruj Pari, respectively ("ray stars"). This aquatic theme is also shared by an archaic name of the constellation in Vietnam, where it was once known as sao Cá Liệt (the ponyfish star).
Among Filipino people, the southern cross have various names pertaining to tops, including kasing (Visayan languages), paglong (Bikol), and pasil (Tagalog). It is also called butiti (puffer fish) in Waray.
The Javanese people of Indonesia called this constellation Gubug pèncèng ("raking hut") or lumbung ("the granary"), because the shape of the constellation was like that of a raking hut.
The Southern Cross (α, β, γ and δ Crucis) together with μ Crucis is one of the asterisms used by Bugis sailors for navigation, called bintoéng bola képpang, meaning "incomplete house star"
The Māori name for the Southern Cross is Māhutonga and it is thought of as the anchor (Te Punga) of Tama-rereti's waka (the Milky Way), while the Pointers are its rope. In Tonga it is known as Toloa ("duck"); it is depicted as a duck flying south, with one of his wings (δ Crucis) wounded because Ongo tangata ("two men", α and β Centauri) threw a stone at it. The Coalsack is known as Humu (the "triggerfish"), because of its shape. In Samoa the constellation is called Sumu ("triggerfish") because of its rhomboid shape, while α and β Centauri are called Luatagata (Two Men), just as they are in Tonga. The peoples of the Solomon Islands saw several figures in the Southern Cross. These included a knee protector and a net used to catch Palolo worms. Neighboring peoples in the Marshall Islands saw these stars as a fish. Peninsular Malays also see the likeness of a fish in the Crux, particularly the Scomberomorus or its local name Tohok.
In Mapudungun, the language of Patagonian Mapuches, the name of the Southern Cross is Melipal, which means "four stars". In Quechua, the language of the Inca civilization, Crux is known as "Chakana", which means literally "stair" (chaka, bridge, link; hanan, high, above), but carries a deep symbolism within Quechua mysticism. Alpha and Beta Crucis make up one foot of the Great Rhea, a constellation encompassing Centaurus and Circinus along with the two bright stars. The Great Rhea was a constellation of the Bororo of Brazil. The Mocoví people of Argentina also saw a rhea including the stars of Crux. Their rhea is attacked by two dogs, represented by bright stars in Centaurus and Circinus. The dogs' heads are marked by Alpha and Beta Centauri. The rhea's body is marked by the four main stars of Crux, while its head is Gamma Centauri and its feet are the bright stars of Musca. The Bakairi people of Brazil had a sprawling constellation representing a bird snare. It included the bright stars of Crux, the southern part of Centaurus, Circinus, at least one star in Lupus, the bright stars of Musca, Beta and the optical double star Delta Chamaeleontis: and some of the stars of Volans, and Mensa. The Kalapalo people of Mato Grosso state in Brazil saw the stars of Crux as Aganagi angry bees having emerged from the Coalsack, which they saw as the beehive.
Among Tuaregs, the four most visible stars of Crux are considered iggaren, i.e. four Maerua crassifolia trees. The Tswana people of Botswana saw the constellation as Dithutlwa, two giraffes – Alpha and Beta Crucis forming a male, and Gamma and Delta forming the female. | [
{
"paragraph_id": 0,
"text": "Crux (/krʌks/) is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross. It lies on the southern end of the Milky Way's visible band. The name Crux is Latin for cross. Even though it is the smallest of all 88 modern constellations, Crux is among the most easily distinguished as its four main stars each have an apparent visual magnitude brighter than +2.8. It has attained a high level of cultural significance in many Southern Hemisphere states and nations.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Blue-white α Crucis (Acrux) is the most southerly member of the constellation and, at magnitude 0.8, the brightest. The three other stars of the cross appear clockwise and in order of lessening magnitude: β Crucis (Mimosa), γ Crucis (Gacrux), and δ Crucis (Imai). ε Crucis (Ginan) also lies within the cross asterism. Many of these brighter stars are members of the Scorpius–Centaurus association, a large but loose group of hot blue-white stars that appear to share common origins and motion across the southern Milky Way.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Crux contains four Cepheid variables, each visible to the naked eye under optimum conditions. Crux also contains the bright and colourful open cluster known as the Jewel Box (NGC 4755) on its eastern border. Nearby to the southeast is a large dark nebula spanning 7° by 5° known as the Coalsack Nebula, portions of which are mapped in the neighbouring constellations of Centaurus and Musca.",
"title": ""
},
{
"paragraph_id": 3,
"text": "The bright stars in Crux were known to the Ancient Greeks, where Ptolemy regarded them as part of the constellation Centaurus. They were entirely visible as far north as Britain in the fourth millennium BC. However, the precession of the equinoxes gradually lowered the stars below the European horizon, and they were eventually forgotten by the inhabitants of northern latitudes. By 400 AD, the stars in the constellation now called Crux never rose above the horizon throughout most of Europe. Dante may have known about the constellation in the 14th century, as he describes an asterism of four bright stars in the southern sky in his Divine Comedy. His description, however, may be allegorical, and the similarity to the constellation a coincidence.",
"title": "History"
},
{
"paragraph_id": 4,
"text": "The 15th century Venetian navigator Alvise Cadamosto made note of what was probably the Southern Cross on exiting the Gambia River in 1455, calling it the carro dell'ostro (\"southern chariot\"). However, Cadamosto's accompanying diagram was inaccurate. Historians generally credit João Faras for being the first European to depict it correctly. Faras sketched and described the constellation (calling it \"las guardas\") in a letter written on the beaches of Brazil on 1 May 1500 to the Portuguese monarch.",
"title": "History"
},
{
"paragraph_id": 5,
"text": "Explorer Amerigo Vespucci seems to have observed not only the Southern Cross but also the neighboring Coalsack Nebula on his second voyage in 1501–1502.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "Another early modern description clearly describing Crux as a separate constellation is attributed to Andrea Corsali, an Italian navigator who from 1515–1517 sailed to China and the East Indies in an expedition sponsored by King Manuel I. In 1516, Corsali wrote a letter to the monarch describing his observations of the southern sky, which included a rather crude map of the stars around the south celestial pole including the Southern Cross and the two Magellanic Clouds seen in an external orientation, as on a globe.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "Emery Molyneux and Petrus Plancius have also been cited as the first uranographers (sky mappers) to distinguish Crux as a separate constellation; their representations date from 1592, the former depicting it on his celestial globe and the latter in one of the small celestial maps on his large wall map. Both authors, however, depended on unreliable sources and placed Crux in the wrong position. Crux was first shown in its correct position on the celestial globes of Petrus Plancius and Jodocus Hondius in 1598 and 1600. Its stars were first catalogued separately from Centaurus by Frederick de Houtman in 1603. The constellation was later adopted by Jakob Bartsch in 1624 and Augustin Royer in 1679. Royer is sometimes wrongly cited as initially distinguishing Crux.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "Crux is bordered by the constellations Centaurus (which surrounds it on three sides) on the east, north and west, and Musca to the south. Covering 68 square degrees and 0.165% of the night sky, it is the smallest of the 88 constellations. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is \"Cru\". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of four segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 11 56.13 and 12 57.45 , while the declination coordinates are between −55.68° and −64.70°. Its totality figures at least part of the year south of the 25th parallel north.",
"title": "Characteristics"
},
{
"paragraph_id": 9,
"text": "In tropical regions Crux can be seen in the sky from April to June. Crux is exactly opposite to Cassiopeia on the celestial sphere, and therefore it cannot appear in the sky with the latter at the same time. In this era, south of Cape Town, Adelaide, and Buenos Aires (the 34th parallel south), Crux is circumpolar and thus always appears in the sky.",
"title": "Characteristics"
},
{
"paragraph_id": 10,
"text": "Crux is sometimes confused with the nearby False Cross asterism by stargazers. The False Cross consists of stars in Carina and Vela, is larger and dimmer, does not have a fifth star, and lacks the two prominent nearby \"Pointer Stars\". Between the two is the even larger and dimmer Diamond Cross.",
"title": "Characteristics"
},
{
"paragraph_id": 11,
"text": "Crux is easily visible from the southern hemisphere, south of 35th parallel at practically any time of year as circumpolar. It is also visible near the horizon from tropical latitudes of the northern hemisphere for a few hours every night during the northern winter and spring. For instance, it is visible from Cancun or any other place at latitude 25° N or less at around 10 pm at the end of April. There are 5 main stars. Due to precession, Crux will move closer to the South Pole in the next millennia, up to 67 degrees south declination for the middle of the constellation. However, by the year 14,000 Crux will be visible for most parts of Europe and continental United States which will extend to North Europe by the year 18,000 as it will be less than 30 degrees south declination.",
"title": "Visibility"
},
{
"paragraph_id": 12,
"text": "In the Southern Hemisphere, the Southern Cross is frequently used for navigation in much the same way that Polaris is used in the Northern Hemisphere. Projecting a line from γ to α Crucis (the foot of the crucifix) approximately 4+1⁄2 times beyond gives a point close to the Southern Celestial Pole which is also, coincidentally, where intersects a perpendicular line taken southwards from the east-west axis of Alpha Centauri to Beta Centauri, which are stars at an alike declination to Crux and of a similar width as the cross, but higher magnitude. Argentine gauchos are documented as using Crux for night orientation in the Pampas and Patagonia.",
"title": "Visibility"
},
{
"paragraph_id": 13,
"text": "Alpha and Beta Centauri are of similar declinations (thus distance from the pole) and are often referred as the \"Southern Pointers\" or just \"The Pointers\", allowing people to easily identify the Southern Cross, the constellation of Crux. Very few bright stars lie between Crux and the pole itself, although the constellation Musca is fairly easily recognised immediately south of Crux.",
"title": "Visibility"
},
{
"paragraph_id": 14,
"text": "Down to apparent magnitude +2.5 are 92 stars that shine the brightest as viewed from the Earth. Three of these stars are in Crux making it the most densely populated as to those stars (this being 3.26% of these 92 stars, and in turn being 19.2 times more than the expected 0.17% that would result on a homogenous distribution of all bright stars and a randomised drawing of all 88 constellations, given its area, 0.17% of the sky).",
"title": "Visibility"
},
{
"paragraph_id": 15,
"text": "Within the constellation's borders, there are 49 stars brighter than or equal to apparent magnitude 6.5. The four main stars that form the asterism are Alpha, Beta, Gamma, and Delta Crucis.",
"title": "Features"
},
{
"paragraph_id": 16,
"text": "There is also a fifth star, that is often included with the Southern Cross.",
"title": "Features"
},
{
"paragraph_id": 17,
"text": "There are several other naked-eye stars within the borders of Crux, especially:",
"title": "Features"
},
{
"paragraph_id": 18,
"text": "Unusually, a total of 15 of the 23 brightest stars in Crux are spectrally blue-white B-type stars. Among the five main bright stars, Delta, and probably Alpha and Beta, are likely co-moving B-type members of the Scorpius–Centaurus association, the nearest OB association to the Sun. They are among the highest-mass stellar members of the Lower Centaurus–Crux subgroup of the association, with ages of roughly 10 to 20 million years. Other members include the blue-white stars Zeta, Lambda and both the components of the visual double star, Mu.",
"title": "Features"
},
{
"paragraph_id": 19,
"text": "Crux contains many variable stars. It boasts four Cepheid variables that may all reach naked eye visibility.",
"title": "Features"
},
{
"paragraph_id": 20,
"text": "Other well studied variable stars includes:",
"title": "Features"
},
{
"paragraph_id": 21,
"text": "The star HD 106906 has been found to have a planet—HD 106906 b—that has one of the widest orbits of any currently known planetary-mass companions.",
"title": "Features"
},
{
"paragraph_id": 22,
"text": "Crux is backlit by the multitude of stars of the Scutum-Crux Arm (more commonly called the Scutum-Centaurus Arm) of the Milky Way. This is the main inner arm in the local radial quarter of the galaxy. Part-obscuring this is:",
"title": "Features"
},
{
"paragraph_id": 23,
"text": "A key feature of the Scutum-Crux Arm is:",
"title": "Features"
},
{
"paragraph_id": 24,
"text": "The most prominent feature of Crux is the distinctive asterism known as the Southern Cross. It has great significance in the cultures of the southern hemisphere, particularly of Australia, Brazil, Chile and New Zealand.",
"title": "Cultural significance"
},
{
"paragraph_id": 25,
"text": "Several southern countries and organisations have traditionally used Crux as a national or distinctive symbol. The four or five brightest stars of Crux appear, heraldically standardised in various ways, on the flags of Australia, Brazil, New Zealand, Papua New Guinea and Samoa. They also appear on the flags of the Australian state of Victoria, the Australian Capital Territory, the Northern Territory, as well as the flag of Magallanes Region of Chile, the flag of Londrina (Brazil) and several Argentine provincial flags and emblems (for example, Tierra del Fuego and Santa Cruz). The flag of the Mercosur trading zone displays the four brightest stars. Crux also appears on the Brazilian coat of arms and, as of July 2015, on the cover of Brazilian passports.",
"title": "Cultural significance"
},
{
"paragraph_id": 26,
"text": "Five stars appear in the logo of the Brazilian football team Cruzeiro Esporte Clube and in the insignia of the Order of the Southern Cross, and the cross has featured as name of the Brazilian currency (the cruzeiro from 1942 to 1986 and again from 1990 to 1994). All coins of the current (1998) series of the Brazilian real display the constellation.",
"title": "Cultural significance"
},
{
"paragraph_id": 27,
"text": "Songs and literature reference the Southern Cross, including the Argentine epic poem Martín Fierro. The Argentinian singer Charly García says that he is \"from the Southern Cross\" in the song \"No voy en tren\".",
"title": "Cultural significance"
},
{
"paragraph_id": 28,
"text": "The Cross gets a mention in the lyrics of the Brazilian National Anthem (1909): \"A imagem do Cruzeiro resplandece\" (\"the image of the Cross shines\").",
"title": "Cultural significance"
},
{
"paragraph_id": 29,
"text": "The Southern Cross is mentioned in the Australian National Anthem, \"Beneath our radiant Southern Cross we'll toil with hearts and hands\"",
"title": "Cultural significance"
},
{
"paragraph_id": 30,
"text": "The Southern Cross features in the coat of arms of William Birdwood, 1st Baron Birdwood, the British officer who commanded the Australian and New Zealand Army Corps during the Gallipoli Campaign of the First World War.",
"title": "Cultural significance"
},
{
"paragraph_id": 31,
"text": "The Southern Cross is also mentioned in the Samoan National Anthem. \"Vaai 'i na fetu o lo'u a agiagia ai: Le faailoga lea o Iesu, na maliu ai mo Samoa.\" (\"Look at those stars that are waving on it: This is the symbol of Jesus, who died on it for Samoa.\")",
"title": "Cultural significance"
},
{
"paragraph_id": 32,
"text": "The 1952-53 NBC Television Series Victory At Sea contained a musical number entitled \"Beneath the Southern Cross\".",
"title": "Cultural significance"
},
{
"paragraph_id": 33,
"text": "\"Southern Cross\" is a single released by Crosby, Stills and Nash in 1981. It reached #18 on Billboard Hot 100 in late 1982.",
"title": "Cultural significance"
},
{
"paragraph_id": 34,
"text": "\"The Sign of the Southern Cross\" is a song released by Black Sabbath in 1981. The song was released on the album \"Mob Rules\".",
"title": "Cultural significance"
},
{
"paragraph_id": 35,
"text": "The Order of the Southern Cross is a Brazilian order of chivalry awarded to \"those who have rendered significant service to the Brazilian nation\".",
"title": "Cultural significance"
},
{
"paragraph_id": 36,
"text": "In \"O Sweet Saint Martin's Land\", the lyrics mention the Southern Cross: Thy Southern Cross the night.",
"title": "Cultural significance"
},
{
"paragraph_id": 37,
"text": "A stylized version of Crux appears on the Australian Eureka Flag. The constellation was also used on the dark blue, shield-like patch worn by personnel of the U.S. Army's Americal Division, which was organized in the Southern Hemisphere, on the island of New Caledonia, and also on the blue diamond of the U.S. 1st Marine Division, which fought on the Southern Hemisphere islands of Guadalcanal and New Britain.",
"title": "Cultural significance"
},
{
"paragraph_id": 38,
"text": "The Petersflagge flag of the German East Africa Company of 1885–1920, which included a constellation of five white five-pointed Crux \"stars\" on a red ground, later served as the model for symbolism associated with generic German colonial-oriented organisations: the Reichskolonialbund of 1936–1943 and the Friends of the former German Protectorates [de] (1956/1983 to the present).",
"title": "Cultural significance"
},
{
"paragraph_id": 39,
"text": "Southern Cross station is a major rail terminal in Melbourne, Australia.",
"title": "Cultural significance"
},
{
"paragraph_id": 40,
"text": "The Personal Ordinariate of Our Lady of the Southern Cross is a personal ordinariate of the Roman Catholic Church primarily within the territory of the Australian Catholic Bishops Conference for groups of Anglicans who desire full communion with the Catholic Church in Australia and Asia.",
"title": "Cultural significance"
},
{
"paragraph_id": 41,
"text": "The Knights of the Southern Cross (KSC) is a Catholic fraternal order throughout Australia.",
"title": "Cultural significance"
},
{
"paragraph_id": 42,
"text": "In India, there is a story related to the creation of Trishanku Swarga (त्रिशंकु), meaning Cross (Crux), created by Sage Vishwamitra.",
"title": "Cultural significance"
},
{
"paragraph_id": 43,
"text": "In Chinese, 十字架 (Shí Zì Jià), meaning Cross, refers to an asterism consisting of γ Crucis, α Crucis, β Crucis and δ Crucis.",
"title": "Cultural significance"
},
{
"paragraph_id": 44,
"text": "In Australian Aboriginal astronomy, Crux and the Coalsack mark the head of the 'Emu in the Sky' (which is seen in the dark spaces rather than in the patterns of stars) in several Aboriginal cultures, while Crux itself is said to be a possum sitting in a tree (Boorong people of the Wimmera region of northwestern Victoria), a representation of the sky deity Mirrabooka (Quandamooka people of Stradbroke Island), a stingray (Yolngu people of Arnhem Land), or an eagle (Kaurna people of the Adelaide Plains). Two Pacific constellations also included Gamma Centauri. Torres Strait Islanders in modern-day Australia saw Gamma Centauri as the handle and the four stars as the left hand of Tagai, and the stars of Musca as the trident of the fishing spear he is holding. In Aranda traditions of central Australia, the four Cross stars are the talon of an eagle and Gamma Centauri as its leg.",
"title": "Cultural significance"
},
{
"paragraph_id": 45,
"text": "Various peoples in the East Indies and Brazil viewed the four main stars as the body of a ray. In both Indonesia and Malaysia, it is known as Bintang Pari and Buruj Pari, respectively (\"ray stars\"). This aquatic theme is also shared by an archaic name of the constellation in Vietnam, where it was once known as sao Cá Liệt (the ponyfish star).",
"title": "Cultural significance"
},
{
"paragraph_id": 46,
"text": "Among Filipino people, the southern cross have various names pertaining to tops, including kasing (Visayan languages), paglong (Bikol), and pasil (Tagalog). It is also called butiti (puffer fish) in Waray.",
"title": "Cultural significance"
},
{
"paragraph_id": 47,
"text": "The Javanese people of Indonesia called this constellation Gubug pèncèng (\"raking hut\") or lumbung (\"the granary\"), because the shape of the constellation was like that of a raking hut.",
"title": "Cultural significance"
},
{
"paragraph_id": 48,
"text": "The Southern Cross (α, β, γ and δ Crucis) together with μ Crucis is one of the asterisms used by Bugis sailors for navigation, called bintoéng bola képpang, meaning \"incomplete house star\"",
"title": "Cultural significance"
},
{
"paragraph_id": 49,
"text": "The Māori name for the Southern Cross is Māhutonga and it is thought of as the anchor (Te Punga) of Tama-rereti's waka (the Milky Way), while the Pointers are its rope. In Tonga it is known as Toloa (\"duck\"); it is depicted as a duck flying south, with one of his wings (δ Crucis) wounded because Ongo tangata (\"two men\", α and β Centauri) threw a stone at it. The Coalsack is known as Humu (the \"triggerfish\"), because of its shape. In Samoa the constellation is called Sumu (\"triggerfish\") because of its rhomboid shape, while α and β Centauri are called Luatagata (Two Men), just as they are in Tonga. The peoples of the Solomon Islands saw several figures in the Southern Cross. These included a knee protector and a net used to catch Palolo worms. Neighboring peoples in the Marshall Islands saw these stars as a fish. Peninsular Malays also see the likeness of a fish in the Crux, particularly the Scomberomorus or its local name Tohok.",
"title": "Cultural significance"
},
{
"paragraph_id": 50,
"text": "In Mapudungun, the language of Patagonian Mapuches, the name of the Southern Cross is Melipal, which means \"four stars\". In Quechua, the language of the Inca civilization, Crux is known as \"Chakana\", which means literally \"stair\" (chaka, bridge, link; hanan, high, above), but carries a deep symbolism within Quechua mysticism. Alpha and Beta Crucis make up one foot of the Great Rhea, a constellation encompassing Centaurus and Circinus along with the two bright stars. The Great Rhea was a constellation of the Bororo of Brazil. The Mocoví people of Argentina also saw a rhea including the stars of Crux. Their rhea is attacked by two dogs, represented by bright stars in Centaurus and Circinus. The dogs' heads are marked by Alpha and Beta Centauri. The rhea's body is marked by the four main stars of Crux, while its head is Gamma Centauri and its feet are the bright stars of Musca. The Bakairi people of Brazil had a sprawling constellation representing a bird snare. It included the bright stars of Crux, the southern part of Centaurus, Circinus, at least one star in Lupus, the bright stars of Musca, Beta and the optical double star Delta Chamaeleontis: and some of the stars of Volans, and Mensa. The Kalapalo people of Mato Grosso state in Brazil saw the stars of Crux as Aganagi angry bees having emerged from the Coalsack, which they saw as the beehive.",
"title": "Cultural significance"
},
{
"paragraph_id": 51,
"text": "Among Tuaregs, the four most visible stars of Crux are considered iggaren, i.e. four Maerua crassifolia trees. The Tswana people of Botswana saw the constellation as Dithutlwa, two giraffes – Alpha and Beta Crucis forming a male, and Gamma and Delta forming the female.",
"title": "Cultural significance"
}
] | Crux is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross. It lies on the southern end of the Milky Way's visible band. The name Crux is Latin for cross. Even though it is the smallest of all 88 modern constellations, Crux is among the most easily distinguished as its four main stars each have an apparent visual magnitude brighter than +2.8. It has attained a high level of cultural significance in many Southern Hemisphere states and nations. Blue-white α Crucis (Acrux) is the most southerly member of the constellation and, at magnitude 0.8, the brightest. The three other stars of the cross appear clockwise and in order of lessening magnitude: β Crucis (Mimosa), γ Crucis (Gacrux), and δ Crucis (Imai). ε Crucis (Ginan) also lies within the cross asterism. Many of these brighter stars are members of the Scorpius–Centaurus association, a large but loose group of hot blue-white stars that appear to share common origins and motion across the southern Milky Way. Crux contains four Cepheid variables, each visible to the naked eye under optimum conditions. Crux also contains the bright and colourful open cluster known as the Jewel Box on its eastern border. Nearby to the southeast is a large dark nebula spanning 7° by 5° known as the Coalsack Nebula, portions of which are mapped in the neighbouring constellations of Centaurus and Musca. | 2001-09-16T11:38:56Z | 2023-11-22T06:03:13Z | [
"Template:IPAc-en",
"Template:Sfn",
"Template:Frac",
"Template:Lang",
"Template:ISBN",
"Template:Dead link",
"Template:Citation",
"Template:Sky",
"Template:Short description",
"Template:RA",
"Template:As of",
"Template:More citations needed section",
"Template:Commons and category",
"Template:Stars of Crux",
"Template:Hatgrp",
"Template:Efn",
"Template:Cite news",
"Template:Convert",
"Template:More",
"Template:Cite journal",
"Template:Cite web",
"Template:In lang",
"Template:Further",
"Template:Ill",
"Template:Reflist",
"Template:Navconstel",
"Template:Portal bar",
"Template:Infobox constellation",
"Template:Notelist",
"Template:Cite book"
] | https://en.wikipedia.org/wiki/Crux |
6,360 | Cepheus | Cepheus (Ancient Greek: Κηφεύς Kepheús) may refer to: | [
{
"paragraph_id": 0,
"text": "Cepheus (Ancient Greek: Κηφεύς Kepheús) may refer to:",
"title": ""
}
] | Cepheus may refer to: | 2022-10-07T20:28:37Z | [
"Template:Tocright",
"Template:Disambiguation"
] | https://en.wikipedia.org/wiki/Cepheus |
|
6,361 | Cassiopeia | Cassiopeia or Cassiopea may refer to: | [
{
"paragraph_id": 0,
"text": "Cassiopeia or Cassiopea may refer to:",
"title": ""
}
] | Cassiopeia or Cassiopea may refer to: | 2001-09-16T13:21:40Z | 2023-10-21T19:06:20Z | [
"Template:Wiktionary",
"Template:Tocright",
"Template:Disambiguation"
] | https://en.wikipedia.org/wiki/Cassiopeia |
6,362 | Cetus | Cetus (/ˈsiːtəs/) is a constellation, sometimes called 'the whale' in English. The Cetus was a sea monster in Greek mythology which both Perseus and Heracles needed to slay. Cetus is in the region of the sky that contains other water-related constellations: Aquarius, Pisces and Eridanus.
Cetus is not among the 12 true zodiac constellations in the J2000 epoch, nor classical 12-part zodiac. The ecliptic passes less than 0.25° from one of its corners. Thus the moon and planets will enter Cetus (occulting any stars as a foreground object) in 50% of their successive orbits briefly and the southern part of the sun appears in Cetus for about one day each year. Many asteroids in belts have longer phases occulting the north-western part of Cetus, those with a slightly greater inclination to the ecliptic than the moon and planets.
As seen from Mars, the ecliptic (apparent plane of the sun and also the average plane of the planets which is almost the same) passes into it.
Mira ("wonderful", named by Bayer: Omicron Ceti, a star of the neck of the asterism) was the first variable star to be discovered and the prototype of its class, Mira variables. Over a period of 332 days, it reaches a maximum apparent magnitude of 3 - visible to the naked eye - and dips to a minimum magnitude of 10, invisible to the unaided eye. Its seeming appearance and disappearance gave it its name. Mira pulsates with a minimum size of 400 solar diameters and a maximum size of 500 solar diameters. 420 light-years from Earth, it was discovered by David Fabricius in 1596.
α Ceti, traditionally called Menkar ("the nose"), is a red-hued giant star of magnitude 2.5, 220 light-years from Earth. It is a wide double star; the secondary is 93 Ceti, a blue-white hued star of magnitude 5.6, 440 light-years away. β Ceti, also called Deneb Kaitos and Diphda is the brightest star in Cetus. It is an orange-hued giant star of magnitude 2.0, 96 light-years from Earth. The traditional name "Deneb Kaitos" means "the whale's tail". γ Ceti, Kaffaljidhma ("head of the whale") is a very close double star. The primary is a yellow-hued star of magnitude 3.5, 82 light-years from Earth, and the secondary is a blue-hued star of magnitude 6.6. Tau Ceti is noted for being a near Sun-like star at a distance of 11.9 light-years. It is a yellow-hued main-sequence star of magnitude 3.5.
AA Ceti is a triple star system; the brightest member has a magnitude of 6.2. The primary and secondary are separated by 8.4 arcseconds at an angle of 304 degrees. The tertiary is not visible in telescopes. AA Ceti is an eclipsing variable star; the tertiary star passes in front of the primary and causes the system's apparent magnitude to decrease by 0.5 magnitudes. UV Ceti is an unusual binary variable star. 8.7 light-years from Earth, the system consists of two red dwarfs. Both of magnitude 13. One of the stars is a flare star, which are prone to sudden, random outbursts that last several minutes; these increase the pair's apparent brightness significantly - as high as magnitude 7.
Cetus lies far from the galactic plane, so that many distant galaxies are visible, unobscured by dust from the Milky Way. Of these, the brightest is Messier 77 (NGC 1068), a 9th magnitude spiral galaxy near Delta Ceti. It appears face-on and has a clearly visible nucleus of magnitude 10. About 50 million light-years from Earth, M77 is also a Seyfert galaxy and thus a bright object in the radio spectrum. Recently, the galactic cluster JKCS 041 was confirmed to be the most distant cluster of galaxies yet discovered.
The massive cD galaxy Holmberg 15A is also found in Cetus. As is spiral galaxy NGC 1042 and ultra-diffuse galaxy NGC 1052-DF2.
IC 1613 (Caldwell 51) is an irregular dwarf galaxy near the star 26 Ceti and is a member of the Local Group.
NGC 246 (Caldwell 56), also called the Cetus Ring, is a planetary nebula with a magnitude of 8.0, 1600 light-years from Earth. Among some amateur astronomers, NGC 246 has garnered the nickname "Pac-Man Nebula" because of the arrangement of its central stars and the surrounding star field.
The Wolf–Lundmark–Melotte (WLM) is a barred irregular galaxy discovered in 1909 by Max Wolf, located on the outer edges of the Local Group. The discovery of the nature of the galaxy was accredited to Knut Lundmark and Philibert Jacques Melotte in 1926. It is in the constellation Cetus.
Cetus may have originally been associated with a whale, which would have had mythic status amongst Mesopotamian cultures. It is often now called the Whale, though it is most strongly associated with Cetus the sea-monster, who was slain by Perseus as he saved the princess Andromeda from Poseidon's wrath. It is in the middle of "The Sea" recognised by mythologists, a set of water-associated constellations, its other members being Eridanus, Pisces, Piscis Austrinus and Aquarius.
Cetus has been depicted in many ways throughout its history. In the 17th century, Cetus was depicted as a "dragon fish" by Johann Bayer. Both Willem Blaeu and Andreas Cellarius depicted Cetus as a whale-like creature in the same century. However, Cetus has also been variously depicted with animal heads attached to a piscine body.
In Chinese astronomy, the stars of Cetus are found among two areas: the Black Tortoise of the North (北方玄武, Běi Fāng Xuán Wǔ) and the White Tiger of the West (西方白虎, Xī Fāng Bái Hǔ).
The Tukano and Kobeua people of the Amazon used the stars of Cetus to create a jaguar, representing the god of hurricanes and other violent storms. Lambda, Mu, Xi, Nu, Gamma, and Alpha Ceti represented its head; Omicron, Zeta, and Chi Ceti represented its body; Eta Eri, Tau Cet, and Upsilon Cet marked its legs and feet; and Theta, Eta, and Beta Ceti delineated its tail.
In Hawaii, the constellation was called Na Kuhi, and Mira (Omicron Ceti) may have been called Kane.
USS Cetus (AK-77) was a United States Navy Crater class cargo ship named after the constellation. "Cetus" is the title of a ragtime piano composition by Tom Brier on the album Constellations and a 1967 electronic composition by Olly Wilson. | [
{
"paragraph_id": 0,
"text": "Cetus (/ˈsiːtəs/) is a constellation, sometimes called 'the whale' in English. The Cetus was a sea monster in Greek mythology which both Perseus and Heracles needed to slay. Cetus is in the region of the sky that contains other water-related constellations: Aquarius, Pisces and Eridanus.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Cetus is not among the 12 true zodiac constellations in the J2000 epoch, nor classical 12-part zodiac. The ecliptic passes less than 0.25° from one of its corners. Thus the moon and planets will enter Cetus (occulting any stars as a foreground object) in 50% of their successive orbits briefly and the southern part of the sun appears in Cetus for about one day each year. Many asteroids in belts have longer phases occulting the north-western part of Cetus, those with a slightly greater inclination to the ecliptic than the moon and planets.",
"title": "Features"
},
{
"paragraph_id": 2,
"text": "As seen from Mars, the ecliptic (apparent plane of the sun and also the average plane of the planets which is almost the same) passes into it.",
"title": "Features"
},
{
"paragraph_id": 3,
"text": "Mira (\"wonderful\", named by Bayer: Omicron Ceti, a star of the neck of the asterism) was the first variable star to be discovered and the prototype of its class, Mira variables. Over a period of 332 days, it reaches a maximum apparent magnitude of 3 - visible to the naked eye - and dips to a minimum magnitude of 10, invisible to the unaided eye. Its seeming appearance and disappearance gave it its name. Mira pulsates with a minimum size of 400 solar diameters and a maximum size of 500 solar diameters. 420 light-years from Earth, it was discovered by David Fabricius in 1596.",
"title": "Features"
},
{
"paragraph_id": 4,
"text": "α Ceti, traditionally called Menkar (\"the nose\"), is a red-hued giant star of magnitude 2.5, 220 light-years from Earth. It is a wide double star; the secondary is 93 Ceti, a blue-white hued star of magnitude 5.6, 440 light-years away. β Ceti, also called Deneb Kaitos and Diphda is the brightest star in Cetus. It is an orange-hued giant star of magnitude 2.0, 96 light-years from Earth. The traditional name \"Deneb Kaitos\" means \"the whale's tail\". γ Ceti, Kaffaljidhma (\"head of the whale\") is a very close double star. The primary is a yellow-hued star of magnitude 3.5, 82 light-years from Earth, and the secondary is a blue-hued star of magnitude 6.6. Tau Ceti is noted for being a near Sun-like star at a distance of 11.9 light-years. It is a yellow-hued main-sequence star of magnitude 3.5.",
"title": "Features"
},
{
"paragraph_id": 5,
"text": "AA Ceti is a triple star system; the brightest member has a magnitude of 6.2. The primary and secondary are separated by 8.4 arcseconds at an angle of 304 degrees. The tertiary is not visible in telescopes. AA Ceti is an eclipsing variable star; the tertiary star passes in front of the primary and causes the system's apparent magnitude to decrease by 0.5 magnitudes. UV Ceti is an unusual binary variable star. 8.7 light-years from Earth, the system consists of two red dwarfs. Both of magnitude 13. One of the stars is a flare star, which are prone to sudden, random outbursts that last several minutes; these increase the pair's apparent brightness significantly - as high as magnitude 7.",
"title": "Features"
},
{
"paragraph_id": 6,
"text": "Cetus lies far from the galactic plane, so that many distant galaxies are visible, unobscured by dust from the Milky Way. Of these, the brightest is Messier 77 (NGC 1068), a 9th magnitude spiral galaxy near Delta Ceti. It appears face-on and has a clearly visible nucleus of magnitude 10. About 50 million light-years from Earth, M77 is also a Seyfert galaxy and thus a bright object in the radio spectrum. Recently, the galactic cluster JKCS 041 was confirmed to be the most distant cluster of galaxies yet discovered.",
"title": "Features"
},
{
"paragraph_id": 7,
"text": "The massive cD galaxy Holmberg 15A is also found in Cetus. As is spiral galaxy NGC 1042 and ultra-diffuse galaxy NGC 1052-DF2.",
"title": "Features"
},
{
"paragraph_id": 8,
"text": "IC 1613 (Caldwell 51) is an irregular dwarf galaxy near the star 26 Ceti and is a member of the Local Group.",
"title": "Features"
},
{
"paragraph_id": 9,
"text": "NGC 246 (Caldwell 56), also called the Cetus Ring, is a planetary nebula with a magnitude of 8.0, 1600 light-years from Earth. Among some amateur astronomers, NGC 246 has garnered the nickname \"Pac-Man Nebula\" because of the arrangement of its central stars and the surrounding star field.",
"title": "Features"
},
{
"paragraph_id": 10,
"text": "The Wolf–Lundmark–Melotte (WLM) is a barred irregular galaxy discovered in 1909 by Max Wolf, located on the outer edges of the Local Group. The discovery of the nature of the galaxy was accredited to Knut Lundmark and Philibert Jacques Melotte in 1926. It is in the constellation Cetus.",
"title": "Features"
},
{
"paragraph_id": 11,
"text": "Cetus may have originally been associated with a whale, which would have had mythic status amongst Mesopotamian cultures. It is often now called the Whale, though it is most strongly associated with Cetus the sea-monster, who was slain by Perseus as he saved the princess Andromeda from Poseidon's wrath. It is in the middle of \"The Sea\" recognised by mythologists, a set of water-associated constellations, its other members being Eridanus, Pisces, Piscis Austrinus and Aquarius.",
"title": "History and mythology"
},
{
"paragraph_id": 12,
"text": "Cetus has been depicted in many ways throughout its history. In the 17th century, Cetus was depicted as a \"dragon fish\" by Johann Bayer. Both Willem Blaeu and Andreas Cellarius depicted Cetus as a whale-like creature in the same century. However, Cetus has also been variously depicted with animal heads attached to a piscine body.",
"title": "History and mythology"
},
{
"paragraph_id": 13,
"text": "In Chinese astronomy, the stars of Cetus are found among two areas: the Black Tortoise of the North (北方玄武, Běi Fāng Xuán Wǔ) and the White Tiger of the West (西方白虎, Xī Fāng Bái Hǔ).",
"title": "History and mythology"
},
{
"paragraph_id": 14,
"text": "The Tukano and Kobeua people of the Amazon used the stars of Cetus to create a jaguar, representing the god of hurricanes and other violent storms. Lambda, Mu, Xi, Nu, Gamma, and Alpha Ceti represented its head; Omicron, Zeta, and Chi Ceti represented its body; Eta Eri, Tau Cet, and Upsilon Cet marked its legs and feet; and Theta, Eta, and Beta Ceti delineated its tail.",
"title": "History and mythology"
},
{
"paragraph_id": 15,
"text": "In Hawaii, the constellation was called Na Kuhi, and Mira (Omicron Ceti) may have been called Kane.",
"title": "History and mythology"
},
{
"paragraph_id": 16,
"text": "USS Cetus (AK-77) was a United States Navy Crater class cargo ship named after the constellation. \"Cetus\" is the title of a ragtime piano composition by Tom Brier on the album Constellations and a 1967 electronic composition by Olly Wilson.",
"title": "Namesakes"
}
] | Cetus is a constellation, sometimes called 'the whale' in English. The Cetus was a sea monster in Greek mythology which both Perseus and Heracles needed to slay. Cetus is in the region of the sky that contains other water-related constellations: Aquarius, Pisces and Eridanus. | 2001-09-22T14:59:39Z | 2023-10-27T00:54:20Z | [
"Template:Stars of Cetus",
"Template:Constellations",
"Template:Portal bar",
"Template:Main",
"Template:Sfn",
"Template:Cite book",
"Template:ISBN",
"Template:Wiktionary",
"Template:Cite EB1911",
"Template:Reflist",
"Template:Cite news",
"Template:Commons",
"Template:Short description",
"Template:IPAc-en",
"Template:Infobox constellation",
"Template:Harvnb",
"Template:Citation",
"Template:Authority control",
"Template:Sky",
"Template:About",
"Template:Use dmy dates"
] | https://en.wikipedia.org/wiki/Cetus |
6,363 | Carina (constellation) | Carina (/kəˈraɪnə, kəˈriːnə/ kə-RY-nə, -REE-) is a constellation in the southern sky. Its name is Latin for the keel of a ship, and it was the southern foundation of the larger constellation of Argo Navis (the ship Argo) until it was divided into three pieces, the other two being Puppis (the poop deck), and Vela (the sails of the ship).
Carina was once a part of Argo Navis, the great ship of the mythical Jason and the Argonauts who searched for the Golden Fleece. The constellation of Argo was introduced in ancient Greece. However, due to the massive size of Argo Navis and the sheer number of stars that required separate designation, Nicolas-Louis de Lacaille divided Argo into three sections in 1763, including Carina (the hull or keel). In the 19th century, these three became established as separate constellations, and were formally included in the list of 88 modern IAU constellations in 1930. Lacaille kept a single set of Greek letters for the whole of Argo, and separate sets of Latin letter designations for each of the three sections. Therefore, Carina has the α, β and ε, Vela has γ and δ, Puppis has ζ, and so on.
Carina contains Canopus, a white-hued supergiant that is the second-brightest star in the night sky at magnitude −0.72. Alpha Carinae, as Canopus is formally designated, is 313 light-years from Earth. Its traditional name comes from the mythological Canopus, who was a navigator for Menelaus, king of Sparta.
There are several other stars above magnitude 3 in Carina. Beta Carinae, traditionally called Miaplacidus, is a blue-white-hued star of magnitude 1.7, 111 light-years from Earth. Epsilon Carinae is an orange-hued giant star similarly bright to Miaplacidus at magnitude 1.9; it is 630 light-years from Earth. Another fairly bright star is the blue-white-hued Theta Carinae; it is a magnitude 2.7 star 440 light-years from Earth. Theta Carinae is also the most prominent member of the cluster IC 2602. Iota Carinae is a white-hued supergiant star of magnitude 2.2, 690 light-years from Earth.
Eta Carinae is the most prominent variable star in Carina, with a mass of approximately 100 solar masses and 4 million times as bright as the Sun. It was first discovered to be unusual in 1677, when its magnitude suddenly rose to 4, attracting the attention of Edmond Halley. Eta Carinae is inside NGC 3372, commonly called the Carina Nebula. It had a long outburst in 1827, when it brightened to magnitude 1, only fading to magnitude 1.5 in 1828. Its most prominent outburst made Eta Carinae the equal of Sirius; it brightened to magnitude −1.5 in 1843. In the decades following 1843 it appeared relatively placid, having a magnitude between 6.5 and 7.9. However, in 1998, it brightened again, though only to magnitude 5.0, a far less drastic outburst. Eta Carinae is a binary star, with a companion that has a period of 5.5 years; the two stars are surrounded by the Homunculus Nebula, which is composed of gas that was ejected in 1843.
There are several less prominent variable stars in Carina. l Carinae is a Cepheid variable noted for its brightness; it is the brightest Cepheid that is variable to the unaided eye. It is a yellow-hued supergiant star with a minimum magnitude of 4.2 and a maximum magnitude of 3.3; it has a period of 35.5 days.
Two bright Mira variable stars are in Carina: R Carinae and S Carinae; both stars are red giants. R Carinae has a minimum magnitude of 10.0 and a maximum magnitude of 4.0. Its period is 309 days and it is 416 light-years from Earth. S Carinae is similar, with a minimum magnitude of 10.0 and a maximum magnitude of 5.0. However, S Carinae has a shorter period—150 days, though it is much more distant at 1,300 light-years from Earth.
Carina is home to several double stars and binary stars. Upsilon Carinae is a binary star with two blue-white-hued giant components, 1,600 light-years from Earth. The primary is of magnitude 3.0 and the secondary is of magnitude 6.0; the two components are distinguishable in a small amateur telescope.
Two asterisms are prominent in Carina. The 'Diamond Cross' is composed of the stars Beta, Theta, Upsilon and Omega Carinae. The Diamond Cross is visible south of 20ºN latitude, and is larger but fainter than the Southern Cross in Crux. Flanking the Diamond Cross is the False cross, composed of four stars - two stars in Carina, Iota Carinae and Epsilon Carinae, and two stars in Vela, Kappa Velorum and Delta Velorum - and is often mistaken for the Southern Cross, causing errors in astronavigation.
Carina is known for its namesake nebula, NGC 3372, discovered by French astronomer Nicolas-Louis de Lacaille in 1751, which contains several nebulae. The Carina Nebula overall is an extended emission nebula approximately 8,000 light-years away and 300 light-years wide that includes vast star-forming regions. It has an overall magnitude of 8.0 and an apparent diameter of over 2 degrees. Its central region is called the Keyhole, or the Keyhole Nebula. This was described in 1847 by John Herschel, and likened to a keyhole by Emma Converse in 1873. The Keyhole is about seven light-years wide and is composed mostly of ionized hydrogen, with two major star-forming regions. The Homunculus Nebula is a planetary nebula visible to the naked eye that is being ejected by the erratic luminous blue variable star Eta Carinae, the most massive visible star known. Eta Carinae is so massive that it has reached the theoretical upper limit for the mass of a star and is therefore unstable. It is known for its outbursts; in 1840 it briefly became one of the brightest stars in the sky due to a particularly massive outburst, which largely created the Homunculus Nebula. Because of this instability and history of outbursts, Eta Carinae is considered a prime supernova candidate for the next several hundred thousand years because it has reached the end of its estimated million-year life span.
NGC 2516 is an open cluster that is both quite large (approximately half a degree square) and bright, visible to the unaided eye. It is located 1,100 light-years from Earth and has approximately 80 stars, the brightest of which is a red giant star of magnitude 5.2. NGC 3114 is another open cluster approximately of the same size, though it is more distant at 3,000 light-years from Earth. It is more loose and dim than NGC 2516, as its brightest stars are only 6th magnitude. The most prominent open cluster in Carina is IC 2602, also called the "Southern Pleiades". It contains Theta Carinae, along with several other stars visible to the unaided eye. In total, the cluster possesses approximately 60 stars. The Southern Pleiades is particularly large for an open cluster, with a diameter of approximately one degree. Like IC 2602, NGC 3532 is visible to the unaided eye and is of comparable size. It possesses approximately 150 stars that are arranged in an unusual shape, approximating an ellipse with a dark central area. Several prominent orange giants are among the cluster's bright stars, of the 7th magnitude. Superimposed on the cluster is Chi Carinae, a yellow-white-hued star of magnitude 3.9, far more distant than NGC 3532.
Carina also contains the naked-eye globular cluster NGC 2808. Epsilon Carinae and Upsilon Carinae are double stars visible in small telescopes.
One noted galaxy cluster is 1E 0657-56, the Bullet Cluster. At a distance of 4 billion light-years (redshift 0.296), this galaxy cluster is named for the shock wave seen in the intracluster medium, which resembles the shock wave of a supersonic bullet. The bow shock visible is thought to be due to the smaller galaxy cluster moving through the intracluster medium at a relative speed of 3,000–4,000 kilometers per second to the larger cluster. Because this gravitational interaction has been ongoing for hundreds of millions of years, the smaller cluster is being destroyed and will eventually merge with the larger cluster.
Carina contains the radiant of the Eta Carinids meteor shower, which peaks around January 21 each year.
From China (especially northern China), the stars of Carina can barely be seen. The star Canopus (the south polar star in Chinese astronomy) was located by Chinese astronomers in the Vermilion Bird of the South (南方朱雀, Nán Fāng Zhū Què). The rest of the stars were first classified by Xu Guanggi during the Ming dynasty, based on the knowledge acquired from western star charts, and placed among The Southern Asterisms (近南極星區, Jìnnánjíxīngōu).
Polynesian peoples had no name for the constellation in particular, though they had many names for Canopus. The Māori name Ariki ("High-born"), and the Hawaiian Ke Alii-o-kona-i-ka-lewa, "The Chief of the southern expanse" both attest to the star's prominence in the southern sky, while the Māori Atutahi, "First-light" or "Single-light", and the Tuamotu Te Tau-rari and Marere-te-tavahi, "He who stands alone". refer to the star's solitary nature. It was also called Kapae-poto ("Short horizon"), because it rarely sets from the vantage point of New Zealand, and Kauanga ("Solitary"), when it was the last star visible before sunrise.
Carina is in the southern sky quite near the south celestial pole, making it never set (circumpolar) for most of the southern hemisphere. Due to precession of Earth's axis, by the year 4700 the south celestial pole will be in Carina. Three bright stars in Carina will come within 1 degree of the southern celestial pole and take turns as the southern pole star: Omega Carinae (mag 3.29) in 5600, Upsilon Carinae (mag 2.97) in 6700, and Iota Carinae (mag 2.21) in 7900. About 13,860 CE, the bright Canopus (−0.7) will have a greater declination than −82°.
USS Carina (AK-74) was a United States Navy Crater-class cargo ship named after the constellation.
the Toyota Carina was named after it.
Media related to Carina (constellation) at Wikimedia Commons | [
{
"paragraph_id": 0,
"text": "Carina (/kəˈraɪnə, kəˈriːnə/ kə-RY-nə, -REE-) is a constellation in the southern sky. Its name is Latin for the keel of a ship, and it was the southern foundation of the larger constellation of Argo Navis (the ship Argo) until it was divided into three pieces, the other two being Puppis (the poop deck), and Vela (the sails of the ship).",
"title": ""
},
{
"paragraph_id": 1,
"text": "Carina was once a part of Argo Navis, the great ship of the mythical Jason and the Argonauts who searched for the Golden Fleece. The constellation of Argo was introduced in ancient Greece. However, due to the massive size of Argo Navis and the sheer number of stars that required separate designation, Nicolas-Louis de Lacaille divided Argo into three sections in 1763, including Carina (the hull or keel). In the 19th century, these three became established as separate constellations, and were formally included in the list of 88 modern IAU constellations in 1930. Lacaille kept a single set of Greek letters for the whole of Argo, and separate sets of Latin letter designations for each of the three sections. Therefore, Carina has the α, β and ε, Vela has γ and δ, Puppis has ζ, and so on.",
"title": "History and mythology"
},
{
"paragraph_id": 2,
"text": "Carina contains Canopus, a white-hued supergiant that is the second-brightest star in the night sky at magnitude −0.72. Alpha Carinae, as Canopus is formally designated, is 313 light-years from Earth. Its traditional name comes from the mythological Canopus, who was a navigator for Menelaus, king of Sparta.",
"title": "Notable features"
},
{
"paragraph_id": 3,
"text": "There are several other stars above magnitude 3 in Carina. Beta Carinae, traditionally called Miaplacidus, is a blue-white-hued star of magnitude 1.7, 111 light-years from Earth. Epsilon Carinae is an orange-hued giant star similarly bright to Miaplacidus at magnitude 1.9; it is 630 light-years from Earth. Another fairly bright star is the blue-white-hued Theta Carinae; it is a magnitude 2.7 star 440 light-years from Earth. Theta Carinae is also the most prominent member of the cluster IC 2602. Iota Carinae is a white-hued supergiant star of magnitude 2.2, 690 light-years from Earth.",
"title": "Notable features"
},
{
"paragraph_id": 4,
"text": "Eta Carinae is the most prominent variable star in Carina, with a mass of approximately 100 solar masses and 4 million times as bright as the Sun. It was first discovered to be unusual in 1677, when its magnitude suddenly rose to 4, attracting the attention of Edmond Halley. Eta Carinae is inside NGC 3372, commonly called the Carina Nebula. It had a long outburst in 1827, when it brightened to magnitude 1, only fading to magnitude 1.5 in 1828. Its most prominent outburst made Eta Carinae the equal of Sirius; it brightened to magnitude −1.5 in 1843. In the decades following 1843 it appeared relatively placid, having a magnitude between 6.5 and 7.9. However, in 1998, it brightened again, though only to magnitude 5.0, a far less drastic outburst. Eta Carinae is a binary star, with a companion that has a period of 5.5 years; the two stars are surrounded by the Homunculus Nebula, which is composed of gas that was ejected in 1843.",
"title": "Notable features"
},
{
"paragraph_id": 5,
"text": "There are several less prominent variable stars in Carina. l Carinae is a Cepheid variable noted for its brightness; it is the brightest Cepheid that is variable to the unaided eye. It is a yellow-hued supergiant star with a minimum magnitude of 4.2 and a maximum magnitude of 3.3; it has a period of 35.5 days.",
"title": "Notable features"
},
{
"paragraph_id": 6,
"text": "Two bright Mira variable stars are in Carina: R Carinae and S Carinae; both stars are red giants. R Carinae has a minimum magnitude of 10.0 and a maximum magnitude of 4.0. Its period is 309 days and it is 416 light-years from Earth. S Carinae is similar, with a minimum magnitude of 10.0 and a maximum magnitude of 5.0. However, S Carinae has a shorter period—150 days, though it is much more distant at 1,300 light-years from Earth.",
"title": "Notable features"
},
{
"paragraph_id": 7,
"text": "Carina is home to several double stars and binary stars. Upsilon Carinae is a binary star with two blue-white-hued giant components, 1,600 light-years from Earth. The primary is of magnitude 3.0 and the secondary is of magnitude 6.0; the two components are distinguishable in a small amateur telescope.",
"title": "Notable features"
},
{
"paragraph_id": 8,
"text": "Two asterisms are prominent in Carina. The 'Diamond Cross' is composed of the stars Beta, Theta, Upsilon and Omega Carinae. The Diamond Cross is visible south of 20ºN latitude, and is larger but fainter than the Southern Cross in Crux. Flanking the Diamond Cross is the False cross, composed of four stars - two stars in Carina, Iota Carinae and Epsilon Carinae, and two stars in Vela, Kappa Velorum and Delta Velorum - and is often mistaken for the Southern Cross, causing errors in astronavigation.",
"title": "Notable features"
},
{
"paragraph_id": 9,
"text": "Carina is known for its namesake nebula, NGC 3372, discovered by French astronomer Nicolas-Louis de Lacaille in 1751, which contains several nebulae. The Carina Nebula overall is an extended emission nebula approximately 8,000 light-years away and 300 light-years wide that includes vast star-forming regions. It has an overall magnitude of 8.0 and an apparent diameter of over 2 degrees. Its central region is called the Keyhole, or the Keyhole Nebula. This was described in 1847 by John Herschel, and likened to a keyhole by Emma Converse in 1873. The Keyhole is about seven light-years wide and is composed mostly of ionized hydrogen, with two major star-forming regions. The Homunculus Nebula is a planetary nebula visible to the naked eye that is being ejected by the erratic luminous blue variable star Eta Carinae, the most massive visible star known. Eta Carinae is so massive that it has reached the theoretical upper limit for the mass of a star and is therefore unstable. It is known for its outbursts; in 1840 it briefly became one of the brightest stars in the sky due to a particularly massive outburst, which largely created the Homunculus Nebula. Because of this instability and history of outbursts, Eta Carinae is considered a prime supernova candidate for the next several hundred thousand years because it has reached the end of its estimated million-year life span.",
"title": "Notable features"
},
{
"paragraph_id": 10,
"text": "NGC 2516 is an open cluster that is both quite large (approximately half a degree square) and bright, visible to the unaided eye. It is located 1,100 light-years from Earth and has approximately 80 stars, the brightest of which is a red giant star of magnitude 5.2. NGC 3114 is another open cluster approximately of the same size, though it is more distant at 3,000 light-years from Earth. It is more loose and dim than NGC 2516, as its brightest stars are only 6th magnitude. The most prominent open cluster in Carina is IC 2602, also called the \"Southern Pleiades\". It contains Theta Carinae, along with several other stars visible to the unaided eye. In total, the cluster possesses approximately 60 stars. The Southern Pleiades is particularly large for an open cluster, with a diameter of approximately one degree. Like IC 2602, NGC 3532 is visible to the unaided eye and is of comparable size. It possesses approximately 150 stars that are arranged in an unusual shape, approximating an ellipse with a dark central area. Several prominent orange giants are among the cluster's bright stars, of the 7th magnitude. Superimposed on the cluster is Chi Carinae, a yellow-white-hued star of magnitude 3.9, far more distant than NGC 3532.",
"title": "Notable features"
},
{
"paragraph_id": 11,
"text": "Carina also contains the naked-eye globular cluster NGC 2808. Epsilon Carinae and Upsilon Carinae are double stars visible in small telescopes.",
"title": "Notable features"
},
{
"paragraph_id": 12,
"text": "One noted galaxy cluster is 1E 0657-56, the Bullet Cluster. At a distance of 4 billion light-years (redshift 0.296), this galaxy cluster is named for the shock wave seen in the intracluster medium, which resembles the shock wave of a supersonic bullet. The bow shock visible is thought to be due to the smaller galaxy cluster moving through the intracluster medium at a relative speed of 3,000–4,000 kilometers per second to the larger cluster. Because this gravitational interaction has been ongoing for hundreds of millions of years, the smaller cluster is being destroyed and will eventually merge with the larger cluster.",
"title": "Notable features"
},
{
"paragraph_id": 13,
"text": "Carina contains the radiant of the Eta Carinids meteor shower, which peaks around January 21 each year.",
"title": "Notable features"
},
{
"paragraph_id": 14,
"text": "From China (especially northern China), the stars of Carina can barely be seen. The star Canopus (the south polar star in Chinese astronomy) was located by Chinese astronomers in the Vermilion Bird of the South (南方朱雀, Nán Fāng Zhū Què). The rest of the stars were first classified by Xu Guanggi during the Ming dynasty, based on the knowledge acquired from western star charts, and placed among The Southern Asterisms (近南極星區, Jìnnánjíxīngōu).",
"title": "Equivalents"
},
{
"paragraph_id": 15,
"text": "Polynesian peoples had no name for the constellation in particular, though they had many names for Canopus. The Māori name Ariki (\"High-born\"), and the Hawaiian Ke Alii-o-kona-i-ka-lewa, \"The Chief of the southern expanse\" both attest to the star's prominence in the southern sky, while the Māori Atutahi, \"First-light\" or \"Single-light\", and the Tuamotu Te Tau-rari and Marere-te-tavahi, \"He who stands alone\". refer to the star's solitary nature. It was also called Kapae-poto (\"Short horizon\"), because it rarely sets from the vantage point of New Zealand, and Kauanga (\"Solitary\"), when it was the last star visible before sunrise.",
"title": "Equivalents"
},
{
"paragraph_id": 16,
"text": "Carina is in the southern sky quite near the south celestial pole, making it never set (circumpolar) for most of the southern hemisphere. Due to precession of Earth's axis, by the year 4700 the south celestial pole will be in Carina. Three bright stars in Carina will come within 1 degree of the southern celestial pole and take turns as the southern pole star: Omega Carinae (mag 3.29) in 5600, Upsilon Carinae (mag 2.97) in 6700, and Iota Carinae (mag 2.21) in 7900. About 13,860 CE, the bright Canopus (−0.7) will have a greater declination than −82°.",
"title": "Future"
},
{
"paragraph_id": 17,
"text": "USS Carina (AK-74) was a United States Navy Crater-class cargo ship named after the constellation.",
"title": "Namesakes"
},
{
"paragraph_id": 18,
"text": "the Toyota Carina was named after it.",
"title": "Namesakes"
},
{
"paragraph_id": 19,
"text": "Media related to Carina (constellation) at Wikimedia Commons",
"title": "External links"
}
] | Carina is a constellation in the southern sky. Its name is Latin for the keel of a ship, and it was the southern foundation of the larger constellation of Argo Navis until it was divided into three pieces, the other two being Puppis, and Vela. | 2001-09-16T16:44:54Z | 2023-11-16T01:10:16Z | [
"Template:Cite book",
"Template:Cite web",
"Template:Infobox constellation",
"Template:IPAc-en",
"Template:See also",
"Template:Sfn",
"Template:Stars of Carina",
"Template:Navconstel",
"Template:Short description",
"Template:More references needed",
"Template:Clarify",
"Template:Reflist",
"Template:Commons category-inline",
"Template:Portal bar",
"Template:Authority control",
"Template:Sky",
"Template:Respell",
"Template:USS",
"Template:Cn"
] | https://en.wikipedia.org/wiki/Carina_(constellation) |
6,364 | Camelopardalis | Camelopardalis /kəˌmɛləˈpɑːrdəlɪs/ is a large but faint constellation of the northern sky representing a giraffe. The constellation was introduced in 1612 or 1613 by Petrus Plancius. Some older astronomy books give Camelopardalus or Camelopardus as alternative forms of the name, but the version recognized by the International Astronomical Union matches the genitive form, seen suffixed to most of its key stars.
First attested in English in 1785, the word camelopardalis comes from Latin, and it is the romanization of the Greek "καμηλοπάρδαλις" meaning "giraffe", from "κάμηλος" (kamēlos), "camel" + "πάρδαλις" (pardalis), "spotted", because it has a long neck like a camel and spots like a leopard.
Although Camelopardalis is the 18th largest constellation, it is not a particularly bright constellation, as the brightest stars are only of fourth magnitude. In fact, it only contains four stars brighter than magnitude 5.0.
Other variable stars are U Camelopardalis, VZ Camelopardalis, and Mira variables T Camelopardalis, X Camelopardalis, and R Camelopardalis. RU Camelopardalis is one of the brighter Type II Cepheids visible in the night sky.
In 2011 a supernova was discovered in the constellation.
Camelopardalis is in the part of the celestial sphere facing away from the galactic plane. Accordingly, many distant galaxies are visible within its borders.
The annual May meteor shower Camelopardalids from comet 209P/LINEAR have a radiant in Camelopardalis.
Camelopardalis is not one of Ptolemy's 48 constellations in the Almagest. It was created by Petrus Plancius in 1613. It first appeared in a globe designed by him and produced by Pieter van den Keere. One year later, Jakob Bartsch featured it in his atlas. Johannes Hevelius depicted this constellation in his works which were so influential that it was referred to as Camelopardali Hevelii or abbreviated as Camelopard. Hevel.
Part of the constellation was hived off to form the constellation Sciurus Volans, the Flying Squirrel, by William Croswell in 1810. However this was not taken up by later cartographers.
In Chinese astronomy, the stars of Camelopardalis are located within a group of circumpolar stars called the Purple Forbidden Enclosure (紫微垣 Zǐ Wēi Yuán). | [
{
"paragraph_id": 0,
"text": "Camelopardalis /kəˌmɛləˈpɑːrdəlɪs/ is a large but faint constellation of the northern sky representing a giraffe. The constellation was introduced in 1612 or 1613 by Petrus Plancius. Some older astronomy books give Camelopardalus or Camelopardus as alternative forms of the name, but the version recognized by the International Astronomical Union matches the genitive form, seen suffixed to most of its key stars.",
"title": ""
},
{
"paragraph_id": 1,
"text": "First attested in English in 1785, the word camelopardalis comes from Latin, and it is the romanization of the Greek \"καμηλοπάρδαλις\" meaning \"giraffe\", from \"κάμηλος\" (kamēlos), \"camel\" + \"πάρδαλις\" (pardalis), \"spotted\", because it has a long neck like a camel and spots like a leopard.",
"title": "Etymology"
},
{
"paragraph_id": 2,
"text": "Although Camelopardalis is the 18th largest constellation, it is not a particularly bright constellation, as the brightest stars are only of fourth magnitude. In fact, it only contains four stars brighter than magnitude 5.0.",
"title": "Features"
},
{
"paragraph_id": 3,
"text": "Other variable stars are U Camelopardalis, VZ Camelopardalis, and Mira variables T Camelopardalis, X Camelopardalis, and R Camelopardalis. RU Camelopardalis is one of the brighter Type II Cepheids visible in the night sky.",
"title": "Features"
},
{
"paragraph_id": 4,
"text": "In 2011 a supernova was discovered in the constellation.",
"title": "Features"
},
{
"paragraph_id": 5,
"text": "Camelopardalis is in the part of the celestial sphere facing away from the galactic plane. Accordingly, many distant galaxies are visible within its borders.",
"title": "Features"
},
{
"paragraph_id": 6,
"text": "The annual May meteor shower Camelopardalids from comet 209P/LINEAR have a radiant in Camelopardalis.",
"title": "Features"
},
{
"paragraph_id": 7,
"text": "Camelopardalis is not one of Ptolemy's 48 constellations in the Almagest. It was created by Petrus Plancius in 1613. It first appeared in a globe designed by him and produced by Pieter van den Keere. One year later, Jakob Bartsch featured it in his atlas. Johannes Hevelius depicted this constellation in his works which were so influential that it was referred to as Camelopardali Hevelii or abbreviated as Camelopard. Hevel.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "Part of the constellation was hived off to form the constellation Sciurus Volans, the Flying Squirrel, by William Croswell in 1810. However this was not taken up by later cartographers.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "In Chinese astronomy, the stars of Camelopardalis are located within a group of circumpolar stars called the Purple Forbidden Enclosure (紫微垣 Zǐ Wēi Yuán).",
"title": "Equivalents"
}
] | Camelopardalis is a large but faint constellation of the northern sky representing a giraffe. The constellation was introduced in 1612 or 1613 by Petrus Plancius. Some older astronomy books give Camelopardalus or Camelopardus as alternative forms of the name, but the version recognized by the International Astronomical Union matches the genitive form, seen suffixed to most of its key stars. | 2002-02-25T15:43:11Z | 2023-11-10T01:13:12Z | [
"Template:Constellations",
"Template:Clear",
"Template:Cite web",
"Template:Cite journal",
"Template:Cite magazine",
"Template:Stars of Camelopardalis",
"Template:Wiktionary",
"Template:Commons and category",
"Template:Portal bar",
"Template:Short description",
"Template:IPAc-en",
"Template:Anchor",
"Template:Reflist",
"Template:Cite book",
"Template:Sky",
"Template:Use dmy dates",
"Template:Authority control",
"Template:Infobox constellation",
"Template:Sfn",
"Template:See also",
"Template:Refbegin",
"Template:Refend"
] | https://en.wikipedia.org/wiki/Camelopardalis |
6,365 | Convention of Kanagawa | The Convention of Kanagawa, also known as the Kanagawa Treaty (神奈川条約, Kanagawa Jōyaku) or the Japan–US Treaty of Peace and Amity (日米和親条約, Nichibei Washin Jōyaku), was a treaty signed between the United States and the Tokugawa Shogunate on March 31, 1854. Signed under threat of force, it effectively meant the end of Japan's 220-year-old policy of national seclusion (sakoku) by opening the ports of Shimoda and Hakodate to American vessels. It also ensured the safety of American castaways and established the position of an American consul in Japan. The treaty precipitated the signing of similar treaties establishing diplomatic relations with other Western powers.
Since the beginning of the 17th century, the Tokugawa Shogunate pursued a policy of isolating the country from outside influences. Foreign trade was maintained only with the Dutch and the Chinese and was conducted exclusively at Nagasaki under a strict government monopoly. This "Pax Tokugawa" period is largely associated with domestic peace, social stability, commercial development, and expanded literacy. This policy had two main objectives:
By the early 19th century, this policy of isolation was increasingly under challenge. In 1844, King William II of the Netherlands sent a letter urging Japan to end the isolation policy on its own before change would be forced from the outside. In 1846, an official American expedition led by Commodore James Biddle arrived in Japan asking for ports to be opened for trade but was sent away.
In 1853, United States Navy Commodore Matthew C. Perry was sent with a fleet of warships by U.S. President Millard Fillmore to force the opening of Japanese ports to American trade, through the use of gunboat diplomacy if necessary. President Fillmore's letter shows the U.S. sought trade with Japan to open export markets for American goods like gold from California, enable U.S. ships to refuel in Japanese ports, and secure protections and humane treatment for any American sailors shipwrecked on Japan's shores. The growing commerce between America and China, the presence of American whalers in waters offshore Japan, and the increasing monopolization of potential coaling stations by the British and French in Asia were all contributing factors. The Americans were also driven by concepts of manifest destiny and the desire to impose the "benefits" of western civilization and the Christian religion on what they perceived as backward Asian nations. From the Japanese perspective, increasing contacts with foreign warships and the increasing disparity between western military technology and the Japanese feudal armies created growing concern. The Japanese had been keeping abreast of world events via information gathered from Dutch traders in Dejima and had been forewarned by the Dutch of Perry's voyage. There was a considerable internal debate in Japan on how best to meet this potential threat to Japan's economic and political sovereignty in light of events occurring in China with the Opium Wars.
Perry arrived with four warships at Uraga, at the mouth of Edo Bay on July 8, 1853. He blatantly refused Japanese demands that he proceed to Nagasaki, which was the designated port for foreign contact. After threatening to continue directly on to Edo, the nation's capital, and to burn it to the ground if necessary, he was allowed to land at nearby Kurihama on July 14 and to deliver his letter. Such refusal was intentional, as Perry wrote in his journal: “To show these princes how little I regarded their order for me to depart, on getting on board I immediately ordered the whole squadron underway, not to leave the bay… but to go higher up… would produce a decided influence upon the pride and conceit of the government, and cause a more favorable consideration of the President’s letter." Perry’s power front did not stop with refusing to land in Uraga, but he continued to push the boundaries of the Japanese. He ordered the squadron to survey Edo bay, which led to a stand-off between Japanese officers with swords and Americans with guns. By firing the guns into the water, Perry demonstrated their military might, which greatly affected Japanese perceptions of Perry and the United States. Namely, a perception of fear and disrespect.
Despite years of debate on the isolation policy, Perry's letter created great controversy within the highest levels of the Tokugawa shogunate. The shōgun himself, Tokugawa Ieyoshi, died days after Perry's departure and was succeeded by his sickly young son, Tokugawa Iesada, leaving effective administration in the hands of the Council of Elders (rōjū) led by Abe Masahiro. Abe felt that it was impossible for Japan to resist the American demands by military force and yet was reluctant to take any action on his own authority for such an unprecedented situation. Attempting to legitimize any decision taken, Abe polled all of the daimyō for their opinions. This was the first time that the Tokugawa shogunate had allowed its decision-making to be a matter of public debate and had the unforeseen consequence of portraying the shogunate as weak and indecisive. The results of the poll also failed to provide Abe with an answer; of the 61 known responses, 19 were in favour of accepting the American demands and 19 were equally opposed. Of the remainder, 14 gave vague responses expressing concern of possible war, 7 suggested making temporary concessions and 2 advised that they would simply go along with whatever was decided.
Perry returned again on February 11, 1854, with an even larger force of eight warships and made it clear that he would not be leaving until a treaty was signed. Perry continued his manipulation of the setting, such as keeping himself aloof from lower-ranking officials, implying the use of force, surveying the harbor, and refusing to meet in the designated negotiation sites. Negotiations began on March 8 and proceeded for around one month. Each party shared a performance when Perry arrived. The Americans had a technology demonstration, and the Japanese had a sumo wrestling show. While the new technology awed the Japanese people, Perry was unimpressed by the sumo wrestlers and perceived such performance as foolish and degrading: “This disgusting exhibition did not terminate until the whole twenty-five had, successively, in pairs, displayed their immense powers and savage qualities." The Japanese side gave in to almost all of Perry's demands, with the exception of a commercial agreement modelled after previous American treaties with China, which Perry agreed to defer to a later time. The main controversy centered on the selection of the ports to open, with Perry adamantly rejecting Nagasaki.
The treaty, written in English, Dutch, Chinese and Japanese, was signed on March 31, 1854, at what is now Kaikō Hiroba (Port Opening Square) Yokohama, a site adjacent to the current Yokohama Archives of History. The celebratory events for the signing ceremony included a Kabuki play from the Japanese side and, from the American side, U.S. military band music and blackface minstrelsy.
The "Japan-US Treaty of Peace and Amity" has twelve articles:
At the time, shōgun Tokugawa Iesada was the de facto ruler of Japan; for the Emperor of Japan to interact in any way with foreigners was out of the question. Perry concluded the treaty with representatives of the shogun, led by plenipotentiary Hayashi Akira (林韑) and the text was endorsed subsequently, albeit reluctantly, by Emperor Kōmei. The treaty was ratified on February 21, 1855.
In the short term, the U.S. was content with the agreement since Perry had achieved his primary objective of breaking Japan's sakoku policy and setting the grounds for protection of American citizens and an eventual commercial agreement. On the other hand, the Japanese were forced into this trade, and many saw it as a sign of weakness. The Tokugawa shogunate could point out that the treaty was not actually signed by the shogun, or indeed any of his rōjū, and that it had at least temporarily averted the possibility of immediate military confrontation.
Externally, the treaty led to the United States-Japan Treaty of Amity and Commerce, the "Harris Treaty" of 1858, which allowed the establishment of foreign concessions, extraterritoriality for foreigners, and minimal import taxes for foreign goods. The Japanese chafed under the "unequal treaty system" which characterized Asian and western relations during this period. The Kanagawa treaty was also followed by similar agreements with the United Kingdom (Anglo-Japanese Friendship Treaty, October 1854), Russia (Treaty of Shimoda, February 7, 1855), and France (Treaty of Amity and Commerce between France and Japan, October 9, 1858).
Internally, the treaty had far-reaching consequences. Decisions to suspend previous restrictions on military activities led to re-armament by many domains and further weakened the position of the shogun. Debate over foreign policy and popular outrage over perceived appeasement to the foreign powers was a catalyst for the sonnō jōi movement and a shift in political power from Edo back to the Imperial Court in Kyoto. The opposition of Emperor Kōmei to the treaties further lent support to the tōbaku (overthrow the shogunate) movement, and eventually to the Meiji Restoration, which affected all realms of Japanese life. Following this period came an increase in foreign trade, the rise of Japanese military might, and the later rise of Japanese economic and technological advancement. Westernization at the time was a defense mechanism, but Japan has since found a balance between Western modernity and Japanese tradition. | [
{
"paragraph_id": 0,
"text": "The Convention of Kanagawa, also known as the Kanagawa Treaty (神奈川条約, Kanagawa Jōyaku) or the Japan–US Treaty of Peace and Amity (日米和親条約, Nichibei Washin Jōyaku), was a treaty signed between the United States and the Tokugawa Shogunate on March 31, 1854. Signed under threat of force, it effectively meant the end of Japan's 220-year-old policy of national seclusion (sakoku) by opening the ports of Shimoda and Hakodate to American vessels. It also ensured the safety of American castaways and established the position of an American consul in Japan. The treaty precipitated the signing of similar treaties establishing diplomatic relations with other Western powers.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Since the beginning of the 17th century, the Tokugawa Shogunate pursued a policy of isolating the country from outside influences. Foreign trade was maintained only with the Dutch and the Chinese and was conducted exclusively at Nagasaki under a strict government monopoly. This \"Pax Tokugawa\" period is largely associated with domestic peace, social stability, commercial development, and expanded literacy. This policy had two main objectives:",
"title": "Isolation of Japan"
},
{
"paragraph_id": 2,
"text": "By the early 19th century, this policy of isolation was increasingly under challenge. In 1844, King William II of the Netherlands sent a letter urging Japan to end the isolation policy on its own before change would be forced from the outside. In 1846, an official American expedition led by Commodore James Biddle arrived in Japan asking for ports to be opened for trade but was sent away.",
"title": "Isolation of Japan"
},
{
"paragraph_id": 3,
"text": "In 1853, United States Navy Commodore Matthew C. Perry was sent with a fleet of warships by U.S. President Millard Fillmore to force the opening of Japanese ports to American trade, through the use of gunboat diplomacy if necessary. President Fillmore's letter shows the U.S. sought trade with Japan to open export markets for American goods like gold from California, enable U.S. ships to refuel in Japanese ports, and secure protections and humane treatment for any American sailors shipwrecked on Japan's shores. The growing commerce between America and China, the presence of American whalers in waters offshore Japan, and the increasing monopolization of potential coaling stations by the British and French in Asia were all contributing factors. The Americans were also driven by concepts of manifest destiny and the desire to impose the \"benefits\" of western civilization and the Christian religion on what they perceived as backward Asian nations. From the Japanese perspective, increasing contacts with foreign warships and the increasing disparity between western military technology and the Japanese feudal armies created growing concern. The Japanese had been keeping abreast of world events via information gathered from Dutch traders in Dejima and had been forewarned by the Dutch of Perry's voyage. There was a considerable internal debate in Japan on how best to meet this potential threat to Japan's economic and political sovereignty in light of events occurring in China with the Opium Wars.",
"title": "Perry expedition"
},
{
"paragraph_id": 4,
"text": "Perry arrived with four warships at Uraga, at the mouth of Edo Bay on July 8, 1853. He blatantly refused Japanese demands that he proceed to Nagasaki, which was the designated port for foreign contact. After threatening to continue directly on to Edo, the nation's capital, and to burn it to the ground if necessary, he was allowed to land at nearby Kurihama on July 14 and to deliver his letter. Such refusal was intentional, as Perry wrote in his journal: “To show these princes how little I regarded their order for me to depart, on getting on board I immediately ordered the whole squadron underway, not to leave the bay… but to go higher up… would produce a decided influence upon the pride and conceit of the government, and cause a more favorable consideration of the President’s letter.\" Perry’s power front did not stop with refusing to land in Uraga, but he continued to push the boundaries of the Japanese. He ordered the squadron to survey Edo bay, which led to a stand-off between Japanese officers with swords and Americans with guns. By firing the guns into the water, Perry demonstrated their military might, which greatly affected Japanese perceptions of Perry and the United States. Namely, a perception of fear and disrespect.",
"title": "Perry expedition"
},
{
"paragraph_id": 5,
"text": "Despite years of debate on the isolation policy, Perry's letter created great controversy within the highest levels of the Tokugawa shogunate. The shōgun himself, Tokugawa Ieyoshi, died days after Perry's departure and was succeeded by his sickly young son, Tokugawa Iesada, leaving effective administration in the hands of the Council of Elders (rōjū) led by Abe Masahiro. Abe felt that it was impossible for Japan to resist the American demands by military force and yet was reluctant to take any action on his own authority for such an unprecedented situation. Attempting to legitimize any decision taken, Abe polled all of the daimyō for their opinions. This was the first time that the Tokugawa shogunate had allowed its decision-making to be a matter of public debate and had the unforeseen consequence of portraying the shogunate as weak and indecisive. The results of the poll also failed to provide Abe with an answer; of the 61 known responses, 19 were in favour of accepting the American demands and 19 were equally opposed. Of the remainder, 14 gave vague responses expressing concern of possible war, 7 suggested making temporary concessions and 2 advised that they would simply go along with whatever was decided.",
"title": "Perry expedition"
},
{
"paragraph_id": 6,
"text": "Perry returned again on February 11, 1854, with an even larger force of eight warships and made it clear that he would not be leaving until a treaty was signed. Perry continued his manipulation of the setting, such as keeping himself aloof from lower-ranking officials, implying the use of force, surveying the harbor, and refusing to meet in the designated negotiation sites. Negotiations began on March 8 and proceeded for around one month. Each party shared a performance when Perry arrived. The Americans had a technology demonstration, and the Japanese had a sumo wrestling show. While the new technology awed the Japanese people, Perry was unimpressed by the sumo wrestlers and perceived such performance as foolish and degrading: “This disgusting exhibition did not terminate until the whole twenty-five had, successively, in pairs, displayed their immense powers and savage qualities.\" The Japanese side gave in to almost all of Perry's demands, with the exception of a commercial agreement modelled after previous American treaties with China, which Perry agreed to defer to a later time. The main controversy centered on the selection of the ports to open, with Perry adamantly rejecting Nagasaki.",
"title": "Perry expedition"
},
{
"paragraph_id": 7,
"text": "The treaty, written in English, Dutch, Chinese and Japanese, was signed on March 31, 1854, at what is now Kaikō Hiroba (Port Opening Square) Yokohama, a site adjacent to the current Yokohama Archives of History. The celebratory events for the signing ceremony included a Kabuki play from the Japanese side and, from the American side, U.S. military band music and blackface minstrelsy.",
"title": "Perry expedition"
},
{
"paragraph_id": 8,
"text": "The \"Japan-US Treaty of Peace and Amity\" has twelve articles:",
"title": "Treaty of Peace and Amity (1854)"
},
{
"paragraph_id": 9,
"text": "At the time, shōgun Tokugawa Iesada was the de facto ruler of Japan; for the Emperor of Japan to interact in any way with foreigners was out of the question. Perry concluded the treaty with representatives of the shogun, led by plenipotentiary Hayashi Akira (林韑) and the text was endorsed subsequently, albeit reluctantly, by Emperor Kōmei. The treaty was ratified on February 21, 1855.",
"title": "Treaty of Peace and Amity (1854)"
},
{
"paragraph_id": 10,
"text": "In the short term, the U.S. was content with the agreement since Perry had achieved his primary objective of breaking Japan's sakoku policy and setting the grounds for protection of American citizens and an eventual commercial agreement. On the other hand, the Japanese were forced into this trade, and many saw it as a sign of weakness. The Tokugawa shogunate could point out that the treaty was not actually signed by the shogun, or indeed any of his rōjū, and that it had at least temporarily averted the possibility of immediate military confrontation.",
"title": "Consequences of the treaty"
},
{
"paragraph_id": 11,
"text": "Externally, the treaty led to the United States-Japan Treaty of Amity and Commerce, the \"Harris Treaty\" of 1858, which allowed the establishment of foreign concessions, extraterritoriality for foreigners, and minimal import taxes for foreign goods. The Japanese chafed under the \"unequal treaty system\" which characterized Asian and western relations during this period. The Kanagawa treaty was also followed by similar agreements with the United Kingdom (Anglo-Japanese Friendship Treaty, October 1854), Russia (Treaty of Shimoda, February 7, 1855), and France (Treaty of Amity and Commerce between France and Japan, October 9, 1858).",
"title": "Consequences of the treaty"
},
{
"paragraph_id": 12,
"text": "Internally, the treaty had far-reaching consequences. Decisions to suspend previous restrictions on military activities led to re-armament by many domains and further weakened the position of the shogun. Debate over foreign policy and popular outrage over perceived appeasement to the foreign powers was a catalyst for the sonnō jōi movement and a shift in political power from Edo back to the Imperial Court in Kyoto. The opposition of Emperor Kōmei to the treaties further lent support to the tōbaku (overthrow the shogunate) movement, and eventually to the Meiji Restoration, which affected all realms of Japanese life. Following this period came an increase in foreign trade, the rise of Japanese military might, and the later rise of Japanese economic and technological advancement. Westernization at the time was a defense mechanism, but Japan has since found a balance between Western modernity and Japanese tradition.",
"title": "Consequences of the treaty"
}
] | The Convention of Kanagawa, also known as the Kanagawa Treaty or the Japan–US Treaty of Peace and Amity, was a treaty signed between the United States and the Tokugawa Shogunate on March 31, 1854. Signed under threat of force, it effectively meant the end of Japan's 220-year-old policy of national seclusion (sakoku) by opening the ports of Shimoda and Hakodate to American vessels. It also ensured the safety of American castaways and established the position of an American consul in Japan. The treaty precipitated the signing of similar treaties establishing diplomatic relations with other Western powers. | 2002-02-25T15:51:15Z | 2023-12-28T06:38:42Z | [
"Template:Reflist",
"Template:Cite book",
"Template:Cite thesis",
"Template:OCLC",
"Template:Spoken Wikipedia",
"Template:Nihongo2",
"Template:Rp",
"Template:History of Japan",
"Template:Treaties of Japan",
"Template:Infobox treaty",
"Template:Cite web",
"Template:Doi",
"Template:Nihongo",
"Template:Webarchive",
"Template:Commons category",
"Template:Wikisource",
"Template:Authority control",
"Template:Short description",
"Template:Redirect-distinguish-text",
"Template:Full article",
"Template:ISBN"
] | https://en.wikipedia.org/wiki/Convention_of_Kanagawa |
6,366 | Canis Major | Canis Major is a constellation in the southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin for "greater dog" in contrast to Canis Minor, the "lesser dog"; both figures are commonly represented as following the constellation of Orion the hunter through the sky. The Milky Way passes through Canis Major and several open clusters lie within its borders, most notably M41.
Canis Major contains Sirius, the brightest star in the night sky, known as the "dog star". It is bright because of its proximity to the Solar System. In contrast, the other bright stars of the constellation are stars of great distance and high luminosity. At magnitude 1.5, Epsilon Canis Majoris (Adhara) is the second-brightest star of the constellation and the brightest source of extreme ultraviolet radiation in the night sky. Next in brightness are the yellow-white supergiant Delta (Wezen) at 1.8, the blue-white giant Beta (Mirzam) at 2.0, blue-white supergiants Eta (Aludra) at 2.4 and Omicron at 3.0, and white spectroscopic binary Zeta (Furud), also at 3.0. The red hypergiant VY Canis Majoris is one of the largest stars known, while the neutron star RX J0720.4-3125 has a radius of a mere 5 km.
In ancient Mesopotamia, Sirius, named KAK.SI.SA2 by the Babylonians, was seen as an arrow aiming towards Orion, while the southern stars of Canis Major and a part of Puppis were viewed as a bow, named BAN in the Three Stars Each tablets, dating to around 1100 BC. In the later compendium of Babylonian astronomy and astrology titled MUL.APIN, the arrow, Sirius, was also linked with the warrior Ninurta, and the bow with Ishtar, daughter of Enlil. Ninurta was linked to the later deity Marduk, who was said to have slain the ocean goddess Tiamat with a great bow, and worshipped as the principal deity in Babylon. The Ancient Greeks replaced the bow and arrow depiction with that of a dog.
In Greek Mythology, Canis Major represented the dog Laelaps, a gift from Zeus to Europa; or sometimes the hound of Procris, Diana's nymph; or the one given by Aurora to Cephalus, so famed for its speed that Zeus elevated it to the sky. It was also considered to represent one of Orion's hunting dogs, pursuing Lepus the Hare or helping Orion fight Taurus the Bull; and is referred to in this way by Aratos, Homer and Hesiod. The ancient Greeks refer only to one dog, but by Roman times, Canis Minor appears as Orion's second dog. Alternative names include Canis Sequens and Canis Alter. Canis Syrius was the name used in the 1521 Alfonsine tables.
The Roman myth refers to Canis Major as Custos Europae, the dog guarding Europa but failing to prevent her abduction by Jupiter in the form of a bull, and as Janitor Lethaeus, "the watchdog". In medieval Arab astronomy, the constellation became al-Kalb al-Akbar, "the Greater Dog", transcribed as Alcheleb Alachbar by 17th century writer Edmund Chilmead. Islamic scholar Abū Rayḥān al-Bīrūnī referred to Orion as Kalb al-Jabbār, "the Dog of the Giant". Among the Merazig of Tunisia, shepherds note six constellations that mark the passage of the dry, hot season. One of them, called Merzem, includes the stars of Canis Major and Canis Minor and is the herald of two weeks of hot weather.
In Chinese astronomy, the modern constellation of Canis Major is located in the Vermilion Bird (南方朱雀; Nán Fāng Zhū Què), where the stars were classified in several separate asterisms of stars. The Military Market (軍市; Jūnshì) was a circular pattern of stars containing Nu, Beta, Xi and Xi, and some stars from Lepus. The Wild Cockerel (野雞; Yějī) was at the centre of the Military Market, although it is uncertain which stars depicted what. Schlegel reported that the stars Omicron and Pi Canis Majoris might have been them, while Beta or Nu have also been proposed. Sirius was Tiānláng (天狼), the Celestial Wolf, denoting invasion and plunder. Southeast of the Wolf was the asterism Húshǐ (弧矢), the celestial Bow and Arrow, which was interpreted as containing Delta, Epsilon, Eta and Kappa Canis Majoris and Delta Velorum. Alternatively, the arrow was depicted by Omicron and Eta and aiming at Sirius (the Wolf), while the bow comprised Kappa, Epsilon, Sigma, Delta and 164 Canis Majoris, and Pi and Omicron Puppis.
Both the Māori people and the people of the Tuamotus recognized the figure of Canis Major as a distinct entity, though it was sometimes absorbed into other constellations. Te Huinga-o-Rehua, also called Te Putahi-nui-o-Rehua and Te Kahui-Takurua, ("The Assembly of Rehua" or "The Assembly of Sirius") was a Māori constellation that included both Canis Minor and Canis Major, along with some surrounding stars. Related was Taumata-o-Rehua, also called Pukawanui, the Mirror of Rehua, formed from an undefined group of stars in Canis Major. They called Sirius Rehua and Takarua, corresponding to two of the names for the constellation, though Rehua was a name applied to other stars in various Māori groups and other Polynesian cosmologies. The Tuamotu people called Canis Major Muihanga-hetika-o-Takurua, "the abiding assemblage of Takarua".
The Tharumba people of the Shoalhaven River saw three stars of Canis Major as Wunbula (Bat) and his two wives Murrumbool (Mrs Brown Snake) and Moodtha (Mrs Black Snake); bored of following their husband around, the women try to bury him while he is hunting a wombat down its hole. He spears them and all three are placed in the sky as the constellation Munowra. To the Boorong people of Victoria, Sigma Canis Majoris was Unurgunite (which has become the official name of this star), and its flanking stars Delta and Epsilon were his two wives. The moon (Mityan, "native cat") sought to lure the further wife (Epsilon) away, but Unurgunite assaulted him and he has been wandering the sky ever since.
Canis Major is a constellation in the Southern Hemisphere's summer (or northern hemisphere's winter) sky, bordered by Monoceros (which lies between it and Canis Minor) to the north, Puppis to the east and southeast, Columba to the southwest, and Lepus to the west. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "CMa". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a quadrilateral; in the equatorial coordinate system, the right ascension coordinates of these borders lie between 06 12.5 and 07 27.5 , while the declination coordinates are between −11.03° and −33.25°. Covering 380 square degrees or 0.921% of the sky, it ranks 43rd of the 88 currently-recognized constellations in size.
Canis Major is a prominent constellation because of its many bright stars. These include Sirius (Alpha Canis Majoris), the brightest star in the night sky, as well as three other stars above magnitude 2.0. Furthermore, two other stars are thought to have previously outshone all others in the night sky—Adhara (Epsilon Canis Majoris) shone at −3.99 around 4.7 million years ago, and Mirzam (Beta Canis Majoris) peaked at −3.65 around 4.42 million years ago. Another, NR Canis Majoris, will be brightest at magnitude −0.88 in about 2.87 million years' time.
The German cartographer Johann Bayer used the Greek letters Alpha through Omicron to label the most prominent stars in the constellation, including three adjacent stars as Nu and two further pairs as Xi and Omicron, while subsequent observers designated further stars in the southern parts of the constellation that were hard to discern from Central Europe. Bayer's countryman Johann Elert Bode later added Sigma, Tau and Omega; the French astronomer Nicolas Louis de Lacaille added lettered stars a to k (though none are in use today). John Flamsteed numbered 31 stars, with 3 Canis Majoris being placed by Lacaille into Columba as Delta Columbae (Flamsteed had not recognised Columba as a distinct constellation). He also labelled two stars—his 10 and 13 Canis Majoris—as Kappa and Kappa respectively, but subsequent cartographers such as Francis Baily and John Bevis dropped the fainter former star, leaving Kappa as the sole Kappa. Flamsteed's listing of Nu, Nu, Nu, Xi, Xi, Omicron and Omicron have all remained in use.
Sirius is the brightest star in the night sky at apparent magnitude −1.46 and one of the closest stars to Earth at a distance of 8.6 light-years. Its name comes from the Greek word for "scorching" or "searing". Sirius is also a binary star; its companion Sirius B is a white dwarf with a magnitude of 8.4–10,000 times fainter than Sirius A to observers on Earth. The two orbit each other every 50 years. Their closest approach last occurred in 1993 and they will be at their greatest separation between 2020 and 2025. Sirius was the basis for the ancient Egyptian calendar. The star marked the Great Dog's mouth on Bayer's star atlas.
Flanking Sirius are Beta and Gamma Canis Majoris. Also called Mirzam or Murzim, Beta is a blue-white Beta Cephei variable star of magnitude 2.0, which varies by a few hundredths of a magnitude over a period of six hours. Mirzam is 500 light-years from Earth, and its traditional name means "the announcer", referring to its position as the "announcer" of Sirius, as it rises a few minutes before Sirius does. Gamma, also known as Muliphein, is a fainter star of magnitude 4.12, in reality a blue-white bright giant of spectral type B8IIe located 441 light-years from earth. Iota Canis Majoris, lying between Sirius and Gamma, is another star that has been classified as a Beta Cephei variable, varying from magnitude 4.36 to 4.40 over a period of 1.92 hours. It is a remote blue-white supergiant star of spectral type B3Ib, around 46,000 times as luminous as the sun and, at 2500 light-years distant, 300 times further away than Sirius.
Epsilon, Omicron, Delta, and Eta Canis Majoris were called Al Adzari "the virgins" in medieval Arabic tradition. Marking the dog's right thigh on Bayer's atlas is Epsilon Canis Majoris, also known as Adhara. At magnitude 1.5, it is the second-brightest star in Canis Major and the 23rd-brightest star in the sky. It is a blue-white supergiant of spectral type B2Iab, around 404 light-years from Earth. This star is one of the brightest known extreme ultraviolet sources in the sky. It is a binary star; the secondary is of magnitude 7.4. Its traditional name means "the virgins", having been transferred from the group of stars to Epsilon alone. Nearby is Delta Canis Majoris, also called Wezen. It is a yellow-white supergiant of spectral type F8Iab and magnitude 1.84, around 1605 light-years from Earth. With a traditional name meaning "the weight", Wezen is 17 times as massive and 50,000 times as luminous as the Sun. If located in the centre of the Solar System, it would extend out to Earth as its diameter is 200 times that of the Sun. Only around 10 million years old, Wezen has stopped fusing hydrogen in its core. Its outer envelope is beginning to expand and cool, and in the next 100,000 years it will become a red supergiant as its core fuses heavier and heavier elements. Once it has a core of iron, it will collapse and explode as a supernova. Nestled between Adhara and Wezen lies Sigma Canis Majoris, known as Unurgunite to the Boorong and Wotjobaluk people, a red supergiant of spectral type K7Ib that varies irregularly between magnitudes 3.43 and 3.51.
Also called Aludra, Eta Canis Majoris is a blue-white supergiant of spectral type B5Ia with a luminosity 176,000 times and diameter around 80 times that of the Sun. Classified as an Alpha Cygni type variable star, Aludra varies in brightness from magnitude 2.38 to 2.48 over a period of 4.7 days. It is located 1120 light-years away. To the west of Adhara lies 3.0-magnitude Zeta Canis Majoris or Furud, around 362 light-years distant from Earth. It is a spectroscopic binary, whose components orbit each other every 1.85 years, the combined spectrum indicating a main star of spectral type B2.5V.
Between these stars and Sirius lie Omicron, Omicron, and Pi Canis Majoris. Omicron is a massive supergiant star about 21 times as massive as the Sun. Only 7 million years old, it has exhausted the supply of hydrogen at its core and is now processing helium. It is an Alpha Cygni variable that undergoes periodic non-radial pulsations, which cause its brightness to cycle from magnitude 2.93 to 3.08 over a 24.44-day interval. Omicron is an orange K-type supergiant of spectral type K2.5Iab that is an irregular variable star, varying between apparent magnitudes 3.78 and 3.99. Around 18 times as massive as the Sun, it shines with 65,000 times its luminosity.
North of Sirius lie Theta and Mu Canis Majoris, Theta being the most northerly star with a Bayer designation in the constellation. Around 8 billion years old, it is an orange giant of spectral type K4III that is around as massive as the Sun but has expanded to 30 times the Sun's diameter. Mu is a multiple star system located around 1244 light-years distant, its components discernible in a small telescope as a 5.3-magnitude yellow-hued and 7.1-magnitude bluish star. The brighter star is a giant of spectral type K2III, while the companion is a main sequence star of spectral type B9.5V. Nu Canis Majoris is a yellow-hued giant star of magnitude 5.7, 278 light-years away; it is at the threshold of naked-eye visibility. It has a companion of magnitude 8.1.
At the southern limits of the constellation lie Kappa and Lambda Canis Majoris. Although of similar spectra and nearby each other as viewed from Earth, they are unrelated. Kappa is a Gamma Cassiopeiae variable of spectral type B2Vne, which brightened by 50% between 1963 and 1978, from magnitude 3.96 or so to 3.52. It is around 659 light-years distant. Lambda is a blue-white B-type main sequence dwarf with an apparent magnitude of 4.48 located around 423 light-years from Earth. It is 3.7 times as wide as and 5.5 times as massive as the Sun, and shines with 940 times its luminosity.
Canis Major is also home to many variable stars. EZ Canis Majoris is a Wolf–Rayet star of spectral type WN4 that varies between magnitudes 6.71 and 6.95 over a period of 3.766 days; the cause of its variability is unknown but thought to be related to its stellar wind and rotation. VY Canis Majoris is a remote red hypergiant located approximately 3,800 light-years away from Earth. It is one of largest stars known (sometimes described as the largest known) and is also one of the most luminous with a radius varying from 1,420 to 2,200 times the Sun's radius, and a luminosity around 300,000 times greater than the Sun. Its current mass is about 17 ± 8 solar masses, having shed material from an initial mass of 25–32 solar masses. VY CMa is also surrounded by a red reflection nebula that has been made by the material expelled by the strong stellar winds of its central star. W Canis Majoris is a type of red giant known as a carbon star—a semiregular variable, it ranges between magnitudes 6.27 and 7.09 over a period of 160 days. A cool star, it has a surface temperature of around 2,900 K and a radius 234 times that of the Sun, its distance estimated at 1,444–1,450 light-years from Earth. At the other extreme in size is RX J0720.4-3125, a neutron star with a radius of around 5 km. Exceedingly faint, it has an apparent magnitude of 26.6. Its spectrum and temperature appear to be mysteriously changing over several years. The nature of the changes are unclear, but it is possible they were caused by an event such as the star's absorption of an accretion disc.
Tau Canis Majoris is a Beta Lyrae-type eclipsing multiple star system that varies from magnitude 4.32 to 4.37 over 1.28 days. Its four main component stars are hot O-type stars, with a combined mass 80 times that of the Sun and shining with 500,000 times its luminosity, but little is known of their individual properties. A fifth component, a magnitude 10 star, lies at a distance of 13,000 astronomical units (0.21 ly). The system is only 5 million years old. UW Canis Majoris is another Beta Lyrae-type star 3000 light-years from Earth; it is an eclipsing binary that ranges in magnitude from a minimum of 5.3 to a maximum of 4.8. It has a period of 4.4 days; its components are two massive hot blue stars, one a blue supergiant of spectral type O7.5–8 Iab, while its companion is a slightly cooler, less evolved and less luminous supergiant of spectral type O9.7Ib. The stars are 200,000 and 63,000 times as luminous as the Sun. However the fainter star is the more massive at 19 solar masses to the primary's 16. R Canis Majoris is another eclipsing binary that varies from magnitude 5.7 to 6.34 over 1.13 days, with a third star orbiting these two every 93 years. The shortness of the orbital period and the low ratio between the two main components make this an unusual Algol-type system.
Seven star systems have been found to have planets. Nu Canis Majoris is an ageing orange giant of spectral type K1III of apparent magnitude 3.91 located around 64 light-years distant. Around 1.5 times as massive and 11 times as luminous as the Sun, it is orbited over a period of 763 days by a planet 2.6 times as massive as Jupiter. HD 47536 is likewise an ageing orange giant found to have a planetary system—echoing the fate of the Solar System in a few billion years as the Sun ages and becomes a giant. Conversely, HD 45364 is a star 107 light-years distant that is a little smaller and cooler than the Sun, of spectral type G8V, which has two planets discovered in 2008. With orbital periods of 228 and 342 days, the planets have a 3:2 orbital resonance, which helps stabilise the system. HD 47186 is another sunlike star with two planets; the inner—HD 47186 b—takes four days to complete an orbit and has been classified as a Hot Neptune, while the outer—HD 47186 c—has an eccentric 3.7-year period orbit and has a similar mass to Saturn. HD 43197 is a sunlike star around 183 light-years distant that has two planets: a hot Jupiter-size planet with an eccentric orbit. The other planet, HD 43197 c, is another massive Jovian planet with a slightly oblong orbit outside of its habitable zone.
Z Canis Majoris is a star system a mere 300,000 years old composed of two pre-main-sequence stars—a FU Orionis star and a Herbig Ae/Be star, which has brightened episodically by two magnitudes to magnitude 8 in 1987, 2000, 2004 and 2008. The more massive Herbig Ae/Be star is enveloped in an irregular roughly spherical cocoon of dust that has an inner diameter of 20 AU (3.0×10 km) and outer diameter of 50 AU (7.5×10 km). The cocoon has a hole in it through which light shines that covers an angle of 5 to 10 degrees of its circumference. Both stars are surrounded by a large envelope of in-falling material left over from the original cloud that formed the system. Both stars are emitting jets of material, that of the Herbig Ae/Be star being much larger—11.7 light-years long. Meanwhile, FS Canis Majoris is another star with infra-red emissions indicating a compact shell of dust, but it appears to be a main-sequence star that has absorbed material from a companion. These stars are thought to be significant contributors to interstellar dust.
The band of the Milky Way goes through Canis Major, with only patchy obscurement by interstellar dust clouds. It is bright in the northeastern corner of the constellation, as well as in a triangular area between Adhara, Wezen and Aludra, with many stars visible in binoculars. Canis Major boasts several open clusters. The only Messier object is M41 (NGC 2287), an open cluster with a combined visual magnitude of 4.5, around 2300 light-years from Earth. Located 4 degrees south of Sirius, it contains contrasting blue, yellow and orange stars and covers an area the apparent size of the full moon—in reality around 25 light-years in diameter. Its most luminous stars have already evolved into giants. The brightest is a 6.3-magnitude star of spectral type K3. Located in the field is 12 Canis Majoris, though this star is only 670 light-years distant. NGC 2360, known as Caroline's Cluster after its discoverer Caroline Herschel, is an open cluster located 3.5 degrees west of Muliphein and has a combined apparent magnitude of 7.2. Around 15 light-years in diameter, it is located 3700 light-years away from Earth, and has been dated to around 2.2 billion years old. NGC 2362 is a small, compact open cluster, 5200 light-years from Earth. It contains about 60 stars, of which Tau Canis Majoris is the brightest member. Located around 3 degrees northeast of Wezen, it covers an area around 12 light-years in diameter, though the stars appear huddled around Tau when seen through binoculars. It is a very young open cluster as its member stars are only a few million years old. Lying 2 degrees southwest of NGC 2362 is NGC 2354 a fainter open cluster of magnitude 6.5, with around 15 member stars visible with binoculars. Located around 30' northeast of NGC 2360, NGC 2359 (Thor's Helmet or the Duck Nebula) is a relatively bright emission nebula in Canis Major, with an approximate magnitude of 10, which is 10,000 light-years from Earth. The nebula is shaped by HD 56925, an unstable Wolf–Rayet star embedded within it.
In 2003, an overdensity of stars in the region was announced to be the Canis Major Dwarf, the closest satellite galaxy to Earth. However, there remains debate over whether it represents a disrupted dwarf galaxy or in fact a variation in the thin and thick disk and spiral arm populations of the Milky Way. Investigation of the area yielded only ten RR Lyrae variables—consistent with the Milky Way's halo and thick disk populations rather than a separate dwarf spheroidal galaxy. On the other hand, a globular cluster in Puppis, NGC 2298—which appears to be part of the Canis Major dwarf system—is extremely metal-poor, suggesting it did not arise from the Milky Way's thick disk, and instead is of extragalactic origin.
NGC 2207 and IC 2163 are a pair of face-on interacting spiral galaxies located 125 million light-years from Earth. About 40 million years ago, the two galaxies had a close encounter and are now moving farther apart; nevertheless, the smaller IC 2163 will eventually be incorporated into NGC 2207. As the interaction continues, gas and dust will be perturbed, sparking extensive star formation in both galaxies. Supernovae have been observed in NGC 2207 in 1975 (type Ia SN 1975a), 1999 (the type Ib SN 1999ec), 2003 (type 1b supernova SN 2003H), and 2013 (type II supernova SN 2013ai). Located 16 million light-years distant, ESO 489-056 is an irregular dwarf- and low-surface-brightness galaxy that has one of the lowest metallicities known. | [
{
"paragraph_id": 0,
"text": "Canis Major is a constellation in the southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin for \"greater dog\" in contrast to Canis Minor, the \"lesser dog\"; both figures are commonly represented as following the constellation of Orion the hunter through the sky. The Milky Way passes through Canis Major and several open clusters lie within its borders, most notably M41.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Canis Major contains Sirius, the brightest star in the night sky, known as the \"dog star\". It is bright because of its proximity to the Solar System. In contrast, the other bright stars of the constellation are stars of great distance and high luminosity. At magnitude 1.5, Epsilon Canis Majoris (Adhara) is the second-brightest star of the constellation and the brightest source of extreme ultraviolet radiation in the night sky. Next in brightness are the yellow-white supergiant Delta (Wezen) at 1.8, the blue-white giant Beta (Mirzam) at 2.0, blue-white supergiants Eta (Aludra) at 2.4 and Omicron at 3.0, and white spectroscopic binary Zeta (Furud), also at 3.0. The red hypergiant VY Canis Majoris is one of the largest stars known, while the neutron star RX J0720.4-3125 has a radius of a mere 5 km.",
"title": ""
},
{
"paragraph_id": 2,
"text": "In ancient Mesopotamia, Sirius, named KAK.SI.SA2 by the Babylonians, was seen as an arrow aiming towards Orion, while the southern stars of Canis Major and a part of Puppis were viewed as a bow, named BAN in the Three Stars Each tablets, dating to around 1100 BC. In the later compendium of Babylonian astronomy and astrology titled MUL.APIN, the arrow, Sirius, was also linked with the warrior Ninurta, and the bow with Ishtar, daughter of Enlil. Ninurta was linked to the later deity Marduk, who was said to have slain the ocean goddess Tiamat with a great bow, and worshipped as the principal deity in Babylon. The Ancient Greeks replaced the bow and arrow depiction with that of a dog.",
"title": "History and mythology"
},
{
"paragraph_id": 3,
"text": "In Greek Mythology, Canis Major represented the dog Laelaps, a gift from Zeus to Europa; or sometimes the hound of Procris, Diana's nymph; or the one given by Aurora to Cephalus, so famed for its speed that Zeus elevated it to the sky. It was also considered to represent one of Orion's hunting dogs, pursuing Lepus the Hare or helping Orion fight Taurus the Bull; and is referred to in this way by Aratos, Homer and Hesiod. The ancient Greeks refer only to one dog, but by Roman times, Canis Minor appears as Orion's second dog. Alternative names include Canis Sequens and Canis Alter. Canis Syrius was the name used in the 1521 Alfonsine tables.",
"title": "History and mythology"
},
{
"paragraph_id": 4,
"text": "The Roman myth refers to Canis Major as Custos Europae, the dog guarding Europa but failing to prevent her abduction by Jupiter in the form of a bull, and as Janitor Lethaeus, \"the watchdog\". In medieval Arab astronomy, the constellation became al-Kalb al-Akbar, \"the Greater Dog\", transcribed as Alcheleb Alachbar by 17th century writer Edmund Chilmead. Islamic scholar Abū Rayḥān al-Bīrūnī referred to Orion as Kalb al-Jabbār, \"the Dog of the Giant\". Among the Merazig of Tunisia, shepherds note six constellations that mark the passage of the dry, hot season. One of them, called Merzem, includes the stars of Canis Major and Canis Minor and is the herald of two weeks of hot weather.",
"title": "History and mythology"
},
{
"paragraph_id": 5,
"text": "In Chinese astronomy, the modern constellation of Canis Major is located in the Vermilion Bird (南方朱雀; Nán Fāng Zhū Què), where the stars were classified in several separate asterisms of stars. The Military Market (軍市; Jūnshì) was a circular pattern of stars containing Nu, Beta, Xi and Xi, and some stars from Lepus. The Wild Cockerel (野雞; Yějī) was at the centre of the Military Market, although it is uncertain which stars depicted what. Schlegel reported that the stars Omicron and Pi Canis Majoris might have been them, while Beta or Nu have also been proposed. Sirius was Tiānláng (天狼), the Celestial Wolf, denoting invasion and plunder. Southeast of the Wolf was the asterism Húshǐ (弧矢), the celestial Bow and Arrow, which was interpreted as containing Delta, Epsilon, Eta and Kappa Canis Majoris and Delta Velorum. Alternatively, the arrow was depicted by Omicron and Eta and aiming at Sirius (the Wolf), while the bow comprised Kappa, Epsilon, Sigma, Delta and 164 Canis Majoris, and Pi and Omicron Puppis.",
"title": "History and mythology"
},
{
"paragraph_id": 6,
"text": "Both the Māori people and the people of the Tuamotus recognized the figure of Canis Major as a distinct entity, though it was sometimes absorbed into other constellations. Te Huinga-o-Rehua, also called Te Putahi-nui-o-Rehua and Te Kahui-Takurua, (\"The Assembly of Rehua\" or \"The Assembly of Sirius\") was a Māori constellation that included both Canis Minor and Canis Major, along with some surrounding stars. Related was Taumata-o-Rehua, also called Pukawanui, the Mirror of Rehua, formed from an undefined group of stars in Canis Major. They called Sirius Rehua and Takarua, corresponding to two of the names for the constellation, though Rehua was a name applied to other stars in various Māori groups and other Polynesian cosmologies. The Tuamotu people called Canis Major Muihanga-hetika-o-Takurua, \"the abiding assemblage of Takarua\".",
"title": "History and mythology"
},
{
"paragraph_id": 7,
"text": "The Tharumba people of the Shoalhaven River saw three stars of Canis Major as Wunbula (Bat) and his two wives Murrumbool (Mrs Brown Snake) and Moodtha (Mrs Black Snake); bored of following their husband around, the women try to bury him while he is hunting a wombat down its hole. He spears them and all three are placed in the sky as the constellation Munowra. To the Boorong people of Victoria, Sigma Canis Majoris was Unurgunite (which has become the official name of this star), and its flanking stars Delta and Epsilon were his two wives. The moon (Mityan, \"native cat\") sought to lure the further wife (Epsilon) away, but Unurgunite assaulted him and he has been wandering the sky ever since.",
"title": "History and mythology"
},
{
"paragraph_id": 8,
"text": "Canis Major is a constellation in the Southern Hemisphere's summer (or northern hemisphere's winter) sky, bordered by Monoceros (which lies between it and Canis Minor) to the north, Puppis to the east and southeast, Columba to the southwest, and Lepus to the west. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is \"CMa\". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a quadrilateral; in the equatorial coordinate system, the right ascension coordinates of these borders lie between 06 12.5 and 07 27.5 , while the declination coordinates are between −11.03° and −33.25°. Covering 380 square degrees or 0.921% of the sky, it ranks 43rd of the 88 currently-recognized constellations in size.",
"title": "Characteristics"
},
{
"paragraph_id": 9,
"text": "Canis Major is a prominent constellation because of its many bright stars. These include Sirius (Alpha Canis Majoris), the brightest star in the night sky, as well as three other stars above magnitude 2.0. Furthermore, two other stars are thought to have previously outshone all others in the night sky—Adhara (Epsilon Canis Majoris) shone at −3.99 around 4.7 million years ago, and Mirzam (Beta Canis Majoris) peaked at −3.65 around 4.42 million years ago. Another, NR Canis Majoris, will be brightest at magnitude −0.88 in about 2.87 million years' time.",
"title": "Features"
},
{
"paragraph_id": 10,
"text": "The German cartographer Johann Bayer used the Greek letters Alpha through Omicron to label the most prominent stars in the constellation, including three adjacent stars as Nu and two further pairs as Xi and Omicron, while subsequent observers designated further stars in the southern parts of the constellation that were hard to discern from Central Europe. Bayer's countryman Johann Elert Bode later added Sigma, Tau and Omega; the French astronomer Nicolas Louis de Lacaille added lettered stars a to k (though none are in use today). John Flamsteed numbered 31 stars, with 3 Canis Majoris being placed by Lacaille into Columba as Delta Columbae (Flamsteed had not recognised Columba as a distinct constellation). He also labelled two stars—his 10 and 13 Canis Majoris—as Kappa and Kappa respectively, but subsequent cartographers such as Francis Baily and John Bevis dropped the fainter former star, leaving Kappa as the sole Kappa. Flamsteed's listing of Nu, Nu, Nu, Xi, Xi, Omicron and Omicron have all remained in use.",
"title": "Features"
},
{
"paragraph_id": 11,
"text": "Sirius is the brightest star in the night sky at apparent magnitude −1.46 and one of the closest stars to Earth at a distance of 8.6 light-years. Its name comes from the Greek word for \"scorching\" or \"searing\". Sirius is also a binary star; its companion Sirius B is a white dwarf with a magnitude of 8.4–10,000 times fainter than Sirius A to observers on Earth. The two orbit each other every 50 years. Their closest approach last occurred in 1993 and they will be at their greatest separation between 2020 and 2025. Sirius was the basis for the ancient Egyptian calendar. The star marked the Great Dog's mouth on Bayer's star atlas.",
"title": "Features"
},
{
"paragraph_id": 12,
"text": "Flanking Sirius are Beta and Gamma Canis Majoris. Also called Mirzam or Murzim, Beta is a blue-white Beta Cephei variable star of magnitude 2.0, which varies by a few hundredths of a magnitude over a period of six hours. Mirzam is 500 light-years from Earth, and its traditional name means \"the announcer\", referring to its position as the \"announcer\" of Sirius, as it rises a few minutes before Sirius does. Gamma, also known as Muliphein, is a fainter star of magnitude 4.12, in reality a blue-white bright giant of spectral type B8IIe located 441 light-years from earth. Iota Canis Majoris, lying between Sirius and Gamma, is another star that has been classified as a Beta Cephei variable, varying from magnitude 4.36 to 4.40 over a period of 1.92 hours. It is a remote blue-white supergiant star of spectral type B3Ib, around 46,000 times as luminous as the sun and, at 2500 light-years distant, 300 times further away than Sirius.",
"title": "Features"
},
{
"paragraph_id": 13,
"text": "Epsilon, Omicron, Delta, and Eta Canis Majoris were called Al Adzari \"the virgins\" in medieval Arabic tradition. Marking the dog's right thigh on Bayer's atlas is Epsilon Canis Majoris, also known as Adhara. At magnitude 1.5, it is the second-brightest star in Canis Major and the 23rd-brightest star in the sky. It is a blue-white supergiant of spectral type B2Iab, around 404 light-years from Earth. This star is one of the brightest known extreme ultraviolet sources in the sky. It is a binary star; the secondary is of magnitude 7.4. Its traditional name means \"the virgins\", having been transferred from the group of stars to Epsilon alone. Nearby is Delta Canis Majoris, also called Wezen. It is a yellow-white supergiant of spectral type F8Iab and magnitude 1.84, around 1605 light-years from Earth. With a traditional name meaning \"the weight\", Wezen is 17 times as massive and 50,000 times as luminous as the Sun. If located in the centre of the Solar System, it would extend out to Earth as its diameter is 200 times that of the Sun. Only around 10 million years old, Wezen has stopped fusing hydrogen in its core. Its outer envelope is beginning to expand and cool, and in the next 100,000 years it will become a red supergiant as its core fuses heavier and heavier elements. Once it has a core of iron, it will collapse and explode as a supernova. Nestled between Adhara and Wezen lies Sigma Canis Majoris, known as Unurgunite to the Boorong and Wotjobaluk people, a red supergiant of spectral type K7Ib that varies irregularly between magnitudes 3.43 and 3.51.",
"title": "Features"
},
{
"paragraph_id": 14,
"text": "Also called Aludra, Eta Canis Majoris is a blue-white supergiant of spectral type B5Ia with a luminosity 176,000 times and diameter around 80 times that of the Sun. Classified as an Alpha Cygni type variable star, Aludra varies in brightness from magnitude 2.38 to 2.48 over a period of 4.7 days. It is located 1120 light-years away. To the west of Adhara lies 3.0-magnitude Zeta Canis Majoris or Furud, around 362 light-years distant from Earth. It is a spectroscopic binary, whose components orbit each other every 1.85 years, the combined spectrum indicating a main star of spectral type B2.5V.",
"title": "Features"
},
{
"paragraph_id": 15,
"text": "Between these stars and Sirius lie Omicron, Omicron, and Pi Canis Majoris. Omicron is a massive supergiant star about 21 times as massive as the Sun. Only 7 million years old, it has exhausted the supply of hydrogen at its core and is now processing helium. It is an Alpha Cygni variable that undergoes periodic non-radial pulsations, which cause its brightness to cycle from magnitude 2.93 to 3.08 over a 24.44-day interval. Omicron is an orange K-type supergiant of spectral type K2.5Iab that is an irregular variable star, varying between apparent magnitudes 3.78 and 3.99. Around 18 times as massive as the Sun, it shines with 65,000 times its luminosity.",
"title": "Features"
},
{
"paragraph_id": 16,
"text": "North of Sirius lie Theta and Mu Canis Majoris, Theta being the most northerly star with a Bayer designation in the constellation. Around 8 billion years old, it is an orange giant of spectral type K4III that is around as massive as the Sun but has expanded to 30 times the Sun's diameter. Mu is a multiple star system located around 1244 light-years distant, its components discernible in a small telescope as a 5.3-magnitude yellow-hued and 7.1-magnitude bluish star. The brighter star is a giant of spectral type K2III, while the companion is a main sequence star of spectral type B9.5V. Nu Canis Majoris is a yellow-hued giant star of magnitude 5.7, 278 light-years away; it is at the threshold of naked-eye visibility. It has a companion of magnitude 8.1.",
"title": "Features"
},
{
"paragraph_id": 17,
"text": "At the southern limits of the constellation lie Kappa and Lambda Canis Majoris. Although of similar spectra and nearby each other as viewed from Earth, they are unrelated. Kappa is a Gamma Cassiopeiae variable of spectral type B2Vne, which brightened by 50% between 1963 and 1978, from magnitude 3.96 or so to 3.52. It is around 659 light-years distant. Lambda is a blue-white B-type main sequence dwarf with an apparent magnitude of 4.48 located around 423 light-years from Earth. It is 3.7 times as wide as and 5.5 times as massive as the Sun, and shines with 940 times its luminosity.",
"title": "Features"
},
{
"paragraph_id": 18,
"text": "Canis Major is also home to many variable stars. EZ Canis Majoris is a Wolf–Rayet star of spectral type WN4 that varies between magnitudes 6.71 and 6.95 over a period of 3.766 days; the cause of its variability is unknown but thought to be related to its stellar wind and rotation. VY Canis Majoris is a remote red hypergiant located approximately 3,800 light-years away from Earth. It is one of largest stars known (sometimes described as the largest known) and is also one of the most luminous with a radius varying from 1,420 to 2,200 times the Sun's radius, and a luminosity around 300,000 times greater than the Sun. Its current mass is about 17 ± 8 solar masses, having shed material from an initial mass of 25–32 solar masses. VY CMa is also surrounded by a red reflection nebula that has been made by the material expelled by the strong stellar winds of its central star. W Canis Majoris is a type of red giant known as a carbon star—a semiregular variable, it ranges between magnitudes 6.27 and 7.09 over a period of 160 days. A cool star, it has a surface temperature of around 2,900 K and a radius 234 times that of the Sun, its distance estimated at 1,444–1,450 light-years from Earth. At the other extreme in size is RX J0720.4-3125, a neutron star with a radius of around 5 km. Exceedingly faint, it has an apparent magnitude of 26.6. Its spectrum and temperature appear to be mysteriously changing over several years. The nature of the changes are unclear, but it is possible they were caused by an event such as the star's absorption of an accretion disc.",
"title": "Features"
},
{
"paragraph_id": 19,
"text": "Tau Canis Majoris is a Beta Lyrae-type eclipsing multiple star system that varies from magnitude 4.32 to 4.37 over 1.28 days. Its four main component stars are hot O-type stars, with a combined mass 80 times that of the Sun and shining with 500,000 times its luminosity, but little is known of their individual properties. A fifth component, a magnitude 10 star, lies at a distance of 13,000 astronomical units (0.21 ly). The system is only 5 million years old. UW Canis Majoris is another Beta Lyrae-type star 3000 light-years from Earth; it is an eclipsing binary that ranges in magnitude from a minimum of 5.3 to a maximum of 4.8. It has a period of 4.4 days; its components are two massive hot blue stars, one a blue supergiant of spectral type O7.5–8 Iab, while its companion is a slightly cooler, less evolved and less luminous supergiant of spectral type O9.7Ib. The stars are 200,000 and 63,000 times as luminous as the Sun. However the fainter star is the more massive at 19 solar masses to the primary's 16. R Canis Majoris is another eclipsing binary that varies from magnitude 5.7 to 6.34 over 1.13 days, with a third star orbiting these two every 93 years. The shortness of the orbital period and the low ratio between the two main components make this an unusual Algol-type system.",
"title": "Features"
},
{
"paragraph_id": 20,
"text": "Seven star systems have been found to have planets. Nu Canis Majoris is an ageing orange giant of spectral type K1III of apparent magnitude 3.91 located around 64 light-years distant. Around 1.5 times as massive and 11 times as luminous as the Sun, it is orbited over a period of 763 days by a planet 2.6 times as massive as Jupiter. HD 47536 is likewise an ageing orange giant found to have a planetary system—echoing the fate of the Solar System in a few billion years as the Sun ages and becomes a giant. Conversely, HD 45364 is a star 107 light-years distant that is a little smaller and cooler than the Sun, of spectral type G8V, which has two planets discovered in 2008. With orbital periods of 228 and 342 days, the planets have a 3:2 orbital resonance, which helps stabilise the system. HD 47186 is another sunlike star with two planets; the inner—HD 47186 b—takes four days to complete an orbit and has been classified as a Hot Neptune, while the outer—HD 47186 c—has an eccentric 3.7-year period orbit and has a similar mass to Saturn. HD 43197 is a sunlike star around 183 light-years distant that has two planets: a hot Jupiter-size planet with an eccentric orbit. The other planet, HD 43197 c, is another massive Jovian planet with a slightly oblong orbit outside of its habitable zone.",
"title": "Features"
},
{
"paragraph_id": 21,
"text": "Z Canis Majoris is a star system a mere 300,000 years old composed of two pre-main-sequence stars—a FU Orionis star and a Herbig Ae/Be star, which has brightened episodically by two magnitudes to magnitude 8 in 1987, 2000, 2004 and 2008. The more massive Herbig Ae/Be star is enveloped in an irregular roughly spherical cocoon of dust that has an inner diameter of 20 AU (3.0×10 km) and outer diameter of 50 AU (7.5×10 km). The cocoon has a hole in it through which light shines that covers an angle of 5 to 10 degrees of its circumference. Both stars are surrounded by a large envelope of in-falling material left over from the original cloud that formed the system. Both stars are emitting jets of material, that of the Herbig Ae/Be star being much larger—11.7 light-years long. Meanwhile, FS Canis Majoris is another star with infra-red emissions indicating a compact shell of dust, but it appears to be a main-sequence star that has absorbed material from a companion. These stars are thought to be significant contributors to interstellar dust.",
"title": "Features"
},
{
"paragraph_id": 22,
"text": "The band of the Milky Way goes through Canis Major, with only patchy obscurement by interstellar dust clouds. It is bright in the northeastern corner of the constellation, as well as in a triangular area between Adhara, Wezen and Aludra, with many stars visible in binoculars. Canis Major boasts several open clusters. The only Messier object is M41 (NGC 2287), an open cluster with a combined visual magnitude of 4.5, around 2300 light-years from Earth. Located 4 degrees south of Sirius, it contains contrasting blue, yellow and orange stars and covers an area the apparent size of the full moon—in reality around 25 light-years in diameter. Its most luminous stars have already evolved into giants. The brightest is a 6.3-magnitude star of spectral type K3. Located in the field is 12 Canis Majoris, though this star is only 670 light-years distant. NGC 2360, known as Caroline's Cluster after its discoverer Caroline Herschel, is an open cluster located 3.5 degrees west of Muliphein and has a combined apparent magnitude of 7.2. Around 15 light-years in diameter, it is located 3700 light-years away from Earth, and has been dated to around 2.2 billion years old. NGC 2362 is a small, compact open cluster, 5200 light-years from Earth. It contains about 60 stars, of which Tau Canis Majoris is the brightest member. Located around 3 degrees northeast of Wezen, it covers an area around 12 light-years in diameter, though the stars appear huddled around Tau when seen through binoculars. It is a very young open cluster as its member stars are only a few million years old. Lying 2 degrees southwest of NGC 2362 is NGC 2354 a fainter open cluster of magnitude 6.5, with around 15 member stars visible with binoculars. Located around 30' northeast of NGC 2360, NGC 2359 (Thor's Helmet or the Duck Nebula) is a relatively bright emission nebula in Canis Major, with an approximate magnitude of 10, which is 10,000 light-years from Earth. The nebula is shaped by HD 56925, an unstable Wolf–Rayet star embedded within it.",
"title": "Features"
},
{
"paragraph_id": 23,
"text": "In 2003, an overdensity of stars in the region was announced to be the Canis Major Dwarf, the closest satellite galaxy to Earth. However, there remains debate over whether it represents a disrupted dwarf galaxy or in fact a variation in the thin and thick disk and spiral arm populations of the Milky Way. Investigation of the area yielded only ten RR Lyrae variables—consistent with the Milky Way's halo and thick disk populations rather than a separate dwarf spheroidal galaxy. On the other hand, a globular cluster in Puppis, NGC 2298—which appears to be part of the Canis Major dwarf system—is extremely metal-poor, suggesting it did not arise from the Milky Way's thick disk, and instead is of extragalactic origin.",
"title": "Features"
},
{
"paragraph_id": 24,
"text": "NGC 2207 and IC 2163 are a pair of face-on interacting spiral galaxies located 125 million light-years from Earth. About 40 million years ago, the two galaxies had a close encounter and are now moving farther apart; nevertheless, the smaller IC 2163 will eventually be incorporated into NGC 2207. As the interaction continues, gas and dust will be perturbed, sparking extensive star formation in both galaxies. Supernovae have been observed in NGC 2207 in 1975 (type Ia SN 1975a), 1999 (the type Ib SN 1999ec), 2003 (type 1b supernova SN 2003H), and 2013 (type II supernova SN 2013ai). Located 16 million light-years distant, ESO 489-056 is an irregular dwarf- and low-surface-brightness galaxy that has one of the lowest metallicities known.",
"title": "Features"
}
] | Canis Major is a constellation in the southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin for "greater dog" in contrast to Canis Minor, the "lesser dog"; both figures are commonly represented as following the constellation of Orion the hunter through the sky. The Milky Way passes through Canis Major and several open clusters lie within its borders, most notably M41. Canis Major contains Sirius, the brightest star in the night sky, known as the "dog star". It is bright because of its proximity to the Solar System. In contrast, the other bright stars of the constellation are stars of great distance and high luminosity. At magnitude 1.5, Epsilon Canis Majoris (Adhara) is the second-brightest star of the constellation and the brightest source of extreme ultraviolet radiation in the night sky. Next in brightness are the yellow-white supergiant Delta (Wezen) at 1.8, the blue-white giant Beta (Mirzam) at 2.0, blue-white supergiants Eta (Aludra) at 2.4 and Omicron2 at 3.0, and white spectroscopic binary Zeta (Furud), also at 3.0. The red hypergiant VY Canis Majoris is one of the largest stars known, while the neutron star RX J0720.4-3125 has a radius of a mere 5 km. | 2001-09-16T19:58:06Z | 2023-12-19T16:51:03Z | [
"Template:Commons",
"Template:Stars of Canis Major",
"Template:Redirect-multi",
"Template:Infobox constellation",
"Template:Lang",
"Template:See also",
"Template:Reflist",
"Template:Cite news",
"Template:Sky",
"Template:Short description",
"Template:RA",
"Template:Convert",
"Template:Cite web",
"Template:Portal bar",
"Template:Authority control",
"Template:Featured article",
"Template:Clear",
"Template:Cite journal",
"Template:Cite book",
"Template:Bibcode",
"Template:Cite press release",
"Template:Sfn",
"Template:Lang-zh",
"Template:EB1911 poster",
"Template:Constellations"
] | https://en.wikipedia.org/wiki/Canis_Major |
6,367 | Canis Minor | Canis Minor /ˌkeɪnɪs ˈmaɪnər/ is a small constellation in the northern celestial hemisphere. In the second century, it was included as an asterism, or pattern, of two stars in Ptolemy's 48 constellations, and it is counted among the 88 modern constellations. Its name is Latin for "lesser dog", in contrast to Canis Major, the "greater dog"; both figures are commonly represented as following the constellation of Orion the hunter.
Canis Minor contains only two stars brighter than the fourth magnitude, Procyon (Alpha Canis Minoris), with a magnitude of 0.34, and Gomeisa (Beta Canis Minoris), with a magnitude of 2.9. The constellation's dimmer stars were noted by Johann Bayer, who named eight stars including Alpha and Beta, and John Flamsteed, who numbered fourteen. Procyon is the eighth-brightest star in the night sky, as well as one of the closest. A yellow-white main-sequence star, it has a white dwarf companion. Gomeisa is a blue-white main-sequence star. Luyten's Star is a ninth-magnitude red dwarf and the Solar System's next closest stellar neighbour in the constellation after Procyon. Additionally, Procyon and Luyten's Star are only 1.12 light-years away from each other, and Procyon would be the brightest star in Luyten's Star's sky. The fourth-magnitude HD 66141, which has evolved into an orange giant towards the end of its life cycle, was discovered to have a planet in 2012. There are two faint deep-sky objects within the constellation's borders. The 11 Canis-Minorids are a meteor shower that can be seen in early December.
Though strongly associated with the Classical Greek uranographic tradition, Canis Minor originates from ancient Mesopotamia. Procyon and Gomeisa were called MASH.TAB.BA or "twins" in the Three Stars Each tablets, dating to around 1100 BC. In the later MUL.APIN, this name was also applied to the pairs of Pi and Pi Orionis and Zeta and Xi Orionis. The meaning of MASH.TAB.BA evolved as well, becoming the twin deities Lulal and Latarak, who are on the opposite side of the sky from Papsukkal, the True Shepherd of Heaven in Babylonian mythology. Canis Minor was also given the name DAR.LUGAL, its position defined as "the star which stands behind it [Orion]", in the MUL.APIN; the constellation represents a rooster. This name may have also referred to the constellation Lepus. DAR.LUGAL was also denoted DAR.MUŠEN and DAR.LUGAL.MUŠEN in Babylonia. Canis Minor was then called tarlugallu in Akkadian astronomy.
Canis Minor was one of the original 48 constellations formulated by Ptolemy in his second-century Almagest, in which it was defined as a specific pattern (asterism) of stars; Ptolemy identified only two stars and hence no depiction was possible. The Ancient Greeks called the constellation προκυων/Procyon, "coming before the dog", transliterated into Latin as Antecanis, Praecanis, or variations thereof, by Cicero and others. Roman writers also appended the descriptors parvus, minor or minusculus ("small" or "lesser", for its faintness), septentrionalis ("northerly", for its position in relation to Canis Major), primus (rising "first") or sinister (rising to the "left") to its name Canis. In Greek mythology, Canis Minor was sometimes connected with the Teumessian Fox, a beast turned into stone with its hunter, Laelaps, by Zeus, who placed them in heaven as Canis Major (Laelaps) and Canis Minor (Teumessian Fox). Eratosthenes accompanied the Little Dog with Orion, while Hyginus linked the constellation with Maera, a dog owned by Icarius of Athens. On discovering the latter's death, the dog and Icarius' daughter Erigone took their lives and all three were placed in the sky—Erigone as Virgo and Icarius as Boötes. As a reward for his faithfulness, the dog was placed along the "banks" of the Milky Way, which the ancients believed to be a heavenly river, where he would never suffer from thirst.
The medieval Arabic astronomers maintained the depiction of Canis Minor (al-Kalb al-Asghar in Arabic) as a dog; in his Book of the Fixed Stars, Abd al-Rahman al-Sufi included a diagram of the constellation with a canine figure superimposed. There was one slight difference between the Ptolemaic vision of Canis Minor and the Arabic; al-Sufi claims Mirzam, now assigned to Orion, as part of both Canis Minor—the collar of the dog—and its modern home. The Arabic names for both Procyon and Gomeisa alluded to their proximity and resemblance to Sirius, though they were not direct translations of the Greek; Procyon was called ash-Shi'ra ash-Shamiya, the "Syrian Sirius" and Gomeisa was called ash-Shira al-Ghamisa, the Sirius with bleary eyes. Among the Merazig of Tunisia, shepherds note six constellations that mark the passage of the dry, hot season. One of them, called Merzem, includes the stars of Canis Minor and Canis Major and is the herald of two weeks of hot weather.
The ancient Egyptians thought of this constellation as Anubis, the jackal god.
Alternative names have been proposed: Johann Bayer in the early 17th century termed the constellation Fovea "The Pit", and Morus "Sycamine Tree". Seventeenth-century German poet and author Philippus Caesius linked it to the dog of Tobias from the Apocrypha. Richard A. Proctor gave the constellation the name Felis "the Cat" in 1870 (contrasting with Canis Major, which he had abbreviated to Canis "the Dog"), explaining that he sought to shorten the constellation names to make them more manageable on celestial charts. Occasionally, Canis Minor is confused with Canis Major and given the name Canis Orionis ("Orion's Dog").
In Chinese astronomy, the stars corresponding to Canis Minor lie in the Vermilion Bird of the South (南方朱雀, Nán Fāng Zhū Què). Procyon, Gomeisa and Eta Canis Minoris form an asterism known as Nánhé, the Southern River. With its counterpart, the Northern River Beihe (Castor and Pollux), Nánhé was also associated with a gate or sentry. Along with Zeta and 8 Cancri, 6 Canis Minoris and 11 Canis Minoris formed the asterism Shuiwei, which literally means "water level". Combined with additional stars in Gemini, Shuiwei represented an official who managed floodwaters or a marker of the water level. Neighboring Korea recognized four stars in Canis Minor as part of a different constellation, "the position of the water". This constellation was located in the Red Bird, the southern portion of the sky.
Polynesian peoples often did not recognize Canis Minor as a constellation, but they saw Procyon as significant and often named it; in the Tuamotu Archipelago it was known as Hiro, meaning "twist as a thread of coconut fiber", and Kopu-nui-o-Hiro ("great paunch of Hiro"), which was either a name for the modern figure of Canis Minor or an alternative name for Procyon. Other names included Vena (after a goddess), on Mangaia and Puanga-hori (false Puanga, the name for Rigel), in New Zealand. In the Society Islands, Procyon was called Ana-tahua-vahine-o-toa-te-manava, literally "Aster the priestess of brave heart", figuratively the "pillar for elocution". The Wardaman people of the Northern Territory in Australia gave Procyon and Gomeisa the names Magum and Gurumana, describing them as humans who were transformed into gum trees in the dreamtime. Although their skin had turned to bark, they were able to speak with a human voice by rustling their leaves.
The Aztec calendar was related to their cosmology. The stars of Canis Minor were incorporated along with some stars of Orion and Gemini into an asterism associated with the day called "Water".
Lying directly south of Gemini's bright stars Castor and Pollux, Canis Minor is a small constellation bordered by Monoceros to the south, Gemini to the north, Cancer to the northeast, and Hydra to the east. It does not border Canis Major; Monoceros is in between the two. Covering 183 square degrees, Canis Minor ranks seventy-first of the 88 constellations in size. It appears prominently in the southern sky during the Northern Hemisphere's winter. The constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of 14 sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 07 06.4 and 08 11.4 , while the declination coordinates are between 13.22° and −0.36°. Most visible in the evening sky from January to March, Canis Minor is most prominent at 10 p.m. during mid-February. It is then seen earlier in the evening until July, when it is only visible after sunset before setting itself, and rising in the morning sky before dawn. The constellation's three-letter abbreviation, as adopted by the International Astronomical Union in 1922, is "CMi".
Canis Minor contains only two stars brighter than fourth magnitude. At magnitude 0.34, Procyon, or Alpha Canis Minoris, is the eighth-brightest star in the night sky, as well as one of the closest. Its name means "before the dog" or "preceding the dog" in Greek, as it rises an hour before the "Dog Star", Sirius, of Canis Major. It is a binary star system, consisting of a yellow-white main-sequence star of spectral type F5 IV-V, named Procyon A, and a faint white dwarf companion of spectral type DA, named Procyon B. Procyon B, which orbits the more massive star every 41 years, is of magnitude 10.7. Procyon A is 1.4 times the Sun's mass, while its smaller companion is 0.6 times as massive as the Sun. The system is 11.4 light-years (3.5 parsecs) from Earth, the shortest distance to a northern-hemisphere star of the first magnitude. Gomeisa, or Beta Canis Minoris, with a magnitude of 2.89, is the second-brightest star in Canis Minor. Lying 160 ± 10 light-years (49.1 ± 3.1 parsecs) from the Solar System, it is a blue-white main-sequence star of spectral class B8 Ve. Although fainter to Earth observers, it is much brighter than Procyon, and is 250 times as luminous and three times as massive as the Sun. Although its variations are slight, Gomeisa is classified as a shell star (Gamma Cassiopeiae variable), with a maximum magnitude of 2.84 and a minimum magnitude of 2.92. It is surrounded by a disk of gas which it heats and causes to emit radiation.
Johann Bayer used the Greek letters Alpha to Eta to label the most prominent eight stars in the constellation, designating two stars as Delta (named Delta and Delta). John Flamsteed numbered fourteen stars, discerning a third star he named Delta; his star 12 Canis Minoris was not found subsequently. In Bayer's 1603 work Uranometria, Procyon is located on the dog's belly, and Gomeisa on its neck. Gamma, Epsilon and Eta Canis Minoris lie nearby, marking the dog's neck, crown and chest, respectively. Although it has an apparent magnitude of 4.34, Gamma Canis Minoris is an orange K-type giant of spectral class K3-III C, which lies 318 light-years (97 parsecs) away. Its colour is obvious when seen through binoculars. It is a multiple system, consisting of the spectroscopic binary Gamma A and three optical companions, Gamma B, magnitude 13; Gamma C, magnitude 12; and Gamma D, magnitude 10. The two components of Gamma A orbit each other every 389.2 days, with an eccentric orbit that takes their separation between 2.3 and 1.4 astronomical units (AU). Epsilon Canis Minoris is a yellow bright giant of spectral class G6.5IIb of magnitude of 4.99. It lies 730–810 light-years (220–250 parsecs) from Earth, with 13 times the diameter and 750 times the luminosity of the Sun. Eta Canis Minoris is a giant of spectral class F0III of magnitude 5.24, which has a yellowish hue when viewed through binoculars as well as a faint companion of magnitude 11.1. Located 4 arcseconds from the primary, the companion star is actually around 440 AU from the main star and takes around 5,000 years to orbit it.
Near Procyon, three stars share the name Delta Canis Minoris. Delta is a yellow-white F-type giant of magnitude 5.25 located around 790 light-years (240 parsecs) from Earth. About 360 times as luminous and 3.75 times as massive as the Sun, it is expanding and cooling as it ages, having spent much of its life as a main sequence star of spectrum B6V. Also known as 8 Canis Minoris, Delta is an F-type main-sequence star of spectral type F2V and magnitude 5.59 which is 136 light-years (42 parsecs) distant. The last of the trio, Delta (also known as 9 Canis Minoris), is a white main sequence star of spectral type A0Vnn and magnitude 5.83 which is 680 light-years (210 parsecs) distant. These stars mark the paws of the Lesser Dog's left hind leg, while magnitude 5.13 Zeta marks the right. A blue-white bright giant of spectral type B8II, Zeta lies around 623 light-years (191 parsecs) away from the Solar System.
Lying 222 ± 7 light-years away with an apparent magnitude of 4.39, HD 66141 is 6.8 billion years old and has evolved into an orange giant of spectral type K2III with a diameter around 22 times that of the Sun, and weighing 1.1 solar masses. It is 174 times as luminous as the Sun, with an absolute magnitude of −0.15. HD 66141 was mistakenly named 13 Puppis, as its celestial coordinates were recorded incorrectly when catalogued and hence mistakenly thought to be in the constellation of Puppis; Bode gave it the name Lambda Canis Minoris, which is now obsolete. The orange giant is orbited by a planet, HD 66141b, which was detected in 2012 by measuring the star's radial velocity. The planet has a mass around 6 times that of Jupiter and a period of 480 days.
A red giant of spectral type M4III, BC Canis Minoris lies around 500 light-years (150 parsecs) distant from the Solar System. It is a semiregular variable star that varies between a maximum magnitude of 6.14 and minimum magnitude of 6.42. Periods of 27.7, 143.3 and 208.3 days have been recorded in its pulsations. AZ, AD and BI Canis Minoris are Delta Scuti variables—short period (six hours at most) pulsating stars that have been used as standard candles and as subjects to study astroseismology. AZ is of spectral type A5IV, and ranges between magnitudes 6.44 and 6.51 over a period of 2.3 hours. AD has a spectral type of F2III, and has a maximum magnitude of 9.21 and minimum of 9.51, with a period of approximately 2.95 hours. BI is of spectral type F2 with an apparent magnitude varying around 9.19 and a period of approximately 2.91 hours.
At least three red giants are Mira variables in Canis Minor. S Canis Minoris, of spectral type M7e, is the brightest, ranging from magnitude 6.6 to 13.2 over a period of 332.94 days. V Canis Minoris ranges from magnitude 7.4 to 15.1 over a period of 366.1 days. Similar in magnitude is R Canis Minoris, which has a maximum of 7.3, but a significantly brighter minimum of 11.6. An S-type star, it has a period of 337.8 days.
YZ Canis Minoris is a red dwarf of spectral type M4.5V and magnitude 11.2, roughly three times the size of Jupiter and 20 light-years (6.1 parsecs) from Earth. It is a flare star, emitting unpredictable outbursts of energy for mere minutes, which might be much more powerful analogues of solar flares. Luyten's Star (GJ 273) is a red dwarf star of spectral type M3.5V and close neighbour of the Solar System. Its visual magnitude of 9.9 renders it too faint to be seen with the naked eye, even though it is only 12.39 light-years (3.80 parsecs) away. Fainter still is PSS 544-7, an eighteenth-magnitude red dwarf around 20 per cent the mass of the Sun, located 685 light-years (210 parsecs) from Earth. First noticed in 1991, it is thought to be a cannonball star, shot out of a star cluster and now moving rapidly through space directly away from the galactic disc.
The WZ Sagittae-type dwarf nova DY Canis Minoris (also known as VSX J074727.6+065050) flared up to magnitude 11.4 over January and February 2008 before dropping eight magnitudes to around 19.5 over approximately 80 days. It is a remote binary star system where a white dwarf and low-mass star orbit each other close enough for the former star to draw material off the latter and form an accretion disc. This material builds up until it erupts dramatically.
The Milky Way passes through much of Canis Minor, yet it has few deep-sky objects. William Herschel recorded four objects in his 1786 work Catalogue of Nebulae and Clusters of Stars, including two he mistakenly believed were star clusters. NGC 2459 is a group of five thirteenth- and fourteenth-magnitude stars that appear to lie close together in the sky but are not related. A similar situation has occurred with NGC 2394, also in Canis Minor. This is a collection of fifteen unrelated stars of ninth magnitude and fainter.
Herschel also observed three faint galaxies, two of which are interacting with each other. NGC 2508 is a lenticular galaxy of thirteenth magnitude, estimated at 205 million light-years' distance (63 million parsecs) with a diameter of 80,000 light-years (25,000 parsecs). Named as a single object by Herschel, NGC 2402 is actually a pair of near-adjacent galaxies that appear to be interacting with each other. Only of fourteenth and fifteenth magnitudes, respectively, the elliptical and spiral galaxy are thought to be approximately 245 million light-years distant, and each measure 55,000 light-years in diameter.
The 11 Canis-Minorids, also called the Beta Canis Minorids, are a meteor shower that arise near the fifth-magnitude star 11 Canis Minoris and were discovered in 1964 by Keith Hindley, who investigated their trajectory and proposed a common origin with the comet D/1917 F1 Mellish. However, this conclusion has been refuted subsequently as the number of orbits analysed was low and their trajectories too disparate to confirm a link. They last from 4 to 15 December, peaking over 10 and 11 December. | [
{
"paragraph_id": 0,
"text": "Canis Minor /ˌkeɪnɪs ˈmaɪnər/ is a small constellation in the northern celestial hemisphere. In the second century, it was included as an asterism, or pattern, of two stars in Ptolemy's 48 constellations, and it is counted among the 88 modern constellations. Its name is Latin for \"lesser dog\", in contrast to Canis Major, the \"greater dog\"; both figures are commonly represented as following the constellation of Orion the hunter.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Canis Minor contains only two stars brighter than the fourth magnitude, Procyon (Alpha Canis Minoris), with a magnitude of 0.34, and Gomeisa (Beta Canis Minoris), with a magnitude of 2.9. The constellation's dimmer stars were noted by Johann Bayer, who named eight stars including Alpha and Beta, and John Flamsteed, who numbered fourteen. Procyon is the eighth-brightest star in the night sky, as well as one of the closest. A yellow-white main-sequence star, it has a white dwarf companion. Gomeisa is a blue-white main-sequence star. Luyten's Star is a ninth-magnitude red dwarf and the Solar System's next closest stellar neighbour in the constellation after Procyon. Additionally, Procyon and Luyten's Star are only 1.12 light-years away from each other, and Procyon would be the brightest star in Luyten's Star's sky. The fourth-magnitude HD 66141, which has evolved into an orange giant towards the end of its life cycle, was discovered to have a planet in 2012. There are two faint deep-sky objects within the constellation's borders. The 11 Canis-Minorids are a meteor shower that can be seen in early December.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Though strongly associated with the Classical Greek uranographic tradition, Canis Minor originates from ancient Mesopotamia. Procyon and Gomeisa were called MASH.TAB.BA or \"twins\" in the Three Stars Each tablets, dating to around 1100 BC. In the later MUL.APIN, this name was also applied to the pairs of Pi and Pi Orionis and Zeta and Xi Orionis. The meaning of MASH.TAB.BA evolved as well, becoming the twin deities Lulal and Latarak, who are on the opposite side of the sky from Papsukkal, the True Shepherd of Heaven in Babylonian mythology. Canis Minor was also given the name DAR.LUGAL, its position defined as \"the star which stands behind it [Orion]\", in the MUL.APIN; the constellation represents a rooster. This name may have also referred to the constellation Lepus. DAR.LUGAL was also denoted DAR.MUŠEN and DAR.LUGAL.MUŠEN in Babylonia. Canis Minor was then called tarlugallu in Akkadian astronomy.",
"title": "History and mythology"
},
{
"paragraph_id": 3,
"text": "Canis Minor was one of the original 48 constellations formulated by Ptolemy in his second-century Almagest, in which it was defined as a specific pattern (asterism) of stars; Ptolemy identified only two stars and hence no depiction was possible. The Ancient Greeks called the constellation προκυων/Procyon, \"coming before the dog\", transliterated into Latin as Antecanis, Praecanis, or variations thereof, by Cicero and others. Roman writers also appended the descriptors parvus, minor or minusculus (\"small\" or \"lesser\", for its faintness), septentrionalis (\"northerly\", for its position in relation to Canis Major), primus (rising \"first\") or sinister (rising to the \"left\") to its name Canis. In Greek mythology, Canis Minor was sometimes connected with the Teumessian Fox, a beast turned into stone with its hunter, Laelaps, by Zeus, who placed them in heaven as Canis Major (Laelaps) and Canis Minor (Teumessian Fox). Eratosthenes accompanied the Little Dog with Orion, while Hyginus linked the constellation with Maera, a dog owned by Icarius of Athens. On discovering the latter's death, the dog and Icarius' daughter Erigone took their lives and all three were placed in the sky—Erigone as Virgo and Icarius as Boötes. As a reward for his faithfulness, the dog was placed along the \"banks\" of the Milky Way, which the ancients believed to be a heavenly river, where he would never suffer from thirst.",
"title": "History and mythology"
},
{
"paragraph_id": 4,
"text": "The medieval Arabic astronomers maintained the depiction of Canis Minor (al-Kalb al-Asghar in Arabic) as a dog; in his Book of the Fixed Stars, Abd al-Rahman al-Sufi included a diagram of the constellation with a canine figure superimposed. There was one slight difference between the Ptolemaic vision of Canis Minor and the Arabic; al-Sufi claims Mirzam, now assigned to Orion, as part of both Canis Minor—the collar of the dog—and its modern home. The Arabic names for both Procyon and Gomeisa alluded to their proximity and resemblance to Sirius, though they were not direct translations of the Greek; Procyon was called ash-Shi'ra ash-Shamiya, the \"Syrian Sirius\" and Gomeisa was called ash-Shira al-Ghamisa, the Sirius with bleary eyes. Among the Merazig of Tunisia, shepherds note six constellations that mark the passage of the dry, hot season. One of them, called Merzem, includes the stars of Canis Minor and Canis Major and is the herald of two weeks of hot weather.",
"title": "History and mythology"
},
{
"paragraph_id": 5,
"text": "The ancient Egyptians thought of this constellation as Anubis, the jackal god.",
"title": "History and mythology"
},
{
"paragraph_id": 6,
"text": "Alternative names have been proposed: Johann Bayer in the early 17th century termed the constellation Fovea \"The Pit\", and Morus \"Sycamine Tree\". Seventeenth-century German poet and author Philippus Caesius linked it to the dog of Tobias from the Apocrypha. Richard A. Proctor gave the constellation the name Felis \"the Cat\" in 1870 (contrasting with Canis Major, which he had abbreviated to Canis \"the Dog\"), explaining that he sought to shorten the constellation names to make them more manageable on celestial charts. Occasionally, Canis Minor is confused with Canis Major and given the name Canis Orionis (\"Orion's Dog\").",
"title": "History and mythology"
},
{
"paragraph_id": 7,
"text": "In Chinese astronomy, the stars corresponding to Canis Minor lie in the Vermilion Bird of the South (南方朱雀, Nán Fāng Zhū Què). Procyon, Gomeisa and Eta Canis Minoris form an asterism known as Nánhé, the Southern River. With its counterpart, the Northern River Beihe (Castor and Pollux), Nánhé was also associated with a gate or sentry. Along with Zeta and 8 Cancri, 6 Canis Minoris and 11 Canis Minoris formed the asterism Shuiwei, which literally means \"water level\". Combined with additional stars in Gemini, Shuiwei represented an official who managed floodwaters or a marker of the water level. Neighboring Korea recognized four stars in Canis Minor as part of a different constellation, \"the position of the water\". This constellation was located in the Red Bird, the southern portion of the sky.",
"title": "History and mythology"
},
{
"paragraph_id": 8,
"text": "Polynesian peoples often did not recognize Canis Minor as a constellation, but they saw Procyon as significant and often named it; in the Tuamotu Archipelago it was known as Hiro, meaning \"twist as a thread of coconut fiber\", and Kopu-nui-o-Hiro (\"great paunch of Hiro\"), which was either a name for the modern figure of Canis Minor or an alternative name for Procyon. Other names included Vena (after a goddess), on Mangaia and Puanga-hori (false Puanga, the name for Rigel), in New Zealand. In the Society Islands, Procyon was called Ana-tahua-vahine-o-toa-te-manava, literally \"Aster the priestess of brave heart\", figuratively the \"pillar for elocution\". The Wardaman people of the Northern Territory in Australia gave Procyon and Gomeisa the names Magum and Gurumana, describing them as humans who were transformed into gum trees in the dreamtime. Although their skin had turned to bark, they were able to speak with a human voice by rustling their leaves.",
"title": "History and mythology"
},
{
"paragraph_id": 9,
"text": "The Aztec calendar was related to their cosmology. The stars of Canis Minor were incorporated along with some stars of Orion and Gemini into an asterism associated with the day called \"Water\".",
"title": "History and mythology"
},
{
"paragraph_id": 10,
"text": "Lying directly south of Gemini's bright stars Castor and Pollux, Canis Minor is a small constellation bordered by Monoceros to the south, Gemini to the north, Cancer to the northeast, and Hydra to the east. It does not border Canis Major; Monoceros is in between the two. Covering 183 square degrees, Canis Minor ranks seventy-first of the 88 constellations in size. It appears prominently in the southern sky during the Northern Hemisphere's winter. The constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of 14 sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 07 06.4 and 08 11.4 , while the declination coordinates are between 13.22° and −0.36°. Most visible in the evening sky from January to March, Canis Minor is most prominent at 10 p.m. during mid-February. It is then seen earlier in the evening until July, when it is only visible after sunset before setting itself, and rising in the morning sky before dawn. The constellation's three-letter abbreviation, as adopted by the International Astronomical Union in 1922, is \"CMi\".",
"title": "Characteristics"
},
{
"paragraph_id": 11,
"text": "Canis Minor contains only two stars brighter than fourth magnitude. At magnitude 0.34, Procyon, or Alpha Canis Minoris, is the eighth-brightest star in the night sky, as well as one of the closest. Its name means \"before the dog\" or \"preceding the dog\" in Greek, as it rises an hour before the \"Dog Star\", Sirius, of Canis Major. It is a binary star system, consisting of a yellow-white main-sequence star of spectral type F5 IV-V, named Procyon A, and a faint white dwarf companion of spectral type DA, named Procyon B. Procyon B, which orbits the more massive star every 41 years, is of magnitude 10.7. Procyon A is 1.4 times the Sun's mass, while its smaller companion is 0.6 times as massive as the Sun. The system is 11.4 light-years (3.5 parsecs) from Earth, the shortest distance to a northern-hemisphere star of the first magnitude. Gomeisa, or Beta Canis Minoris, with a magnitude of 2.89, is the second-brightest star in Canis Minor. Lying 160 ± 10 light-years (49.1 ± 3.1 parsecs) from the Solar System, it is a blue-white main-sequence star of spectral class B8 Ve. Although fainter to Earth observers, it is much brighter than Procyon, and is 250 times as luminous and three times as massive as the Sun. Although its variations are slight, Gomeisa is classified as a shell star (Gamma Cassiopeiae variable), with a maximum magnitude of 2.84 and a minimum magnitude of 2.92. It is surrounded by a disk of gas which it heats and causes to emit radiation.",
"title": "Features"
},
{
"paragraph_id": 12,
"text": "Johann Bayer used the Greek letters Alpha to Eta to label the most prominent eight stars in the constellation, designating two stars as Delta (named Delta and Delta). John Flamsteed numbered fourteen stars, discerning a third star he named Delta; his star 12 Canis Minoris was not found subsequently. In Bayer's 1603 work Uranometria, Procyon is located on the dog's belly, and Gomeisa on its neck. Gamma, Epsilon and Eta Canis Minoris lie nearby, marking the dog's neck, crown and chest, respectively. Although it has an apparent magnitude of 4.34, Gamma Canis Minoris is an orange K-type giant of spectral class K3-III C, which lies 318 light-years (97 parsecs) away. Its colour is obvious when seen through binoculars. It is a multiple system, consisting of the spectroscopic binary Gamma A and three optical companions, Gamma B, magnitude 13; Gamma C, magnitude 12; and Gamma D, magnitude 10. The two components of Gamma A orbit each other every 389.2 days, with an eccentric orbit that takes their separation between 2.3 and 1.4 astronomical units (AU). Epsilon Canis Minoris is a yellow bright giant of spectral class G6.5IIb of magnitude of 4.99. It lies 730–810 light-years (220–250 parsecs) from Earth, with 13 times the diameter and 750 times the luminosity of the Sun. Eta Canis Minoris is a giant of spectral class F0III of magnitude 5.24, which has a yellowish hue when viewed through binoculars as well as a faint companion of magnitude 11.1. Located 4 arcseconds from the primary, the companion star is actually around 440 AU from the main star and takes around 5,000 years to orbit it.",
"title": "Features"
},
{
"paragraph_id": 13,
"text": "Near Procyon, three stars share the name Delta Canis Minoris. Delta is a yellow-white F-type giant of magnitude 5.25 located around 790 light-years (240 parsecs) from Earth. About 360 times as luminous and 3.75 times as massive as the Sun, it is expanding and cooling as it ages, having spent much of its life as a main sequence star of spectrum B6V. Also known as 8 Canis Minoris, Delta is an F-type main-sequence star of spectral type F2V and magnitude 5.59 which is 136 light-years (42 parsecs) distant. The last of the trio, Delta (also known as 9 Canis Minoris), is a white main sequence star of spectral type A0Vnn and magnitude 5.83 which is 680 light-years (210 parsecs) distant. These stars mark the paws of the Lesser Dog's left hind leg, while magnitude 5.13 Zeta marks the right. A blue-white bright giant of spectral type B8II, Zeta lies around 623 light-years (191 parsecs) away from the Solar System.",
"title": "Features"
},
{
"paragraph_id": 14,
"text": "Lying 222 ± 7 light-years away with an apparent magnitude of 4.39, HD 66141 is 6.8 billion years old and has evolved into an orange giant of spectral type K2III with a diameter around 22 times that of the Sun, and weighing 1.1 solar masses. It is 174 times as luminous as the Sun, with an absolute magnitude of −0.15. HD 66141 was mistakenly named 13 Puppis, as its celestial coordinates were recorded incorrectly when catalogued and hence mistakenly thought to be in the constellation of Puppis; Bode gave it the name Lambda Canis Minoris, which is now obsolete. The orange giant is orbited by a planet, HD 66141b, which was detected in 2012 by measuring the star's radial velocity. The planet has a mass around 6 times that of Jupiter and a period of 480 days.",
"title": "Features"
},
{
"paragraph_id": 15,
"text": "A red giant of spectral type M4III, BC Canis Minoris lies around 500 light-years (150 parsecs) distant from the Solar System. It is a semiregular variable star that varies between a maximum magnitude of 6.14 and minimum magnitude of 6.42. Periods of 27.7, 143.3 and 208.3 days have been recorded in its pulsations. AZ, AD and BI Canis Minoris are Delta Scuti variables—short period (six hours at most) pulsating stars that have been used as standard candles and as subjects to study astroseismology. AZ is of spectral type A5IV, and ranges between magnitudes 6.44 and 6.51 over a period of 2.3 hours. AD has a spectral type of F2III, and has a maximum magnitude of 9.21 and minimum of 9.51, with a period of approximately 2.95 hours. BI is of spectral type F2 with an apparent magnitude varying around 9.19 and a period of approximately 2.91 hours.",
"title": "Features"
},
{
"paragraph_id": 16,
"text": "At least three red giants are Mira variables in Canis Minor. S Canis Minoris, of spectral type M7e, is the brightest, ranging from magnitude 6.6 to 13.2 over a period of 332.94 days. V Canis Minoris ranges from magnitude 7.4 to 15.1 over a period of 366.1 days. Similar in magnitude is R Canis Minoris, which has a maximum of 7.3, but a significantly brighter minimum of 11.6. An S-type star, it has a period of 337.8 days.",
"title": "Features"
},
{
"paragraph_id": 17,
"text": "YZ Canis Minoris is a red dwarf of spectral type M4.5V and magnitude 11.2, roughly three times the size of Jupiter and 20 light-years (6.1 parsecs) from Earth. It is a flare star, emitting unpredictable outbursts of energy for mere minutes, which might be much more powerful analogues of solar flares. Luyten's Star (GJ 273) is a red dwarf star of spectral type M3.5V and close neighbour of the Solar System. Its visual magnitude of 9.9 renders it too faint to be seen with the naked eye, even though it is only 12.39 light-years (3.80 parsecs) away. Fainter still is PSS 544-7, an eighteenth-magnitude red dwarf around 20 per cent the mass of the Sun, located 685 light-years (210 parsecs) from Earth. First noticed in 1991, it is thought to be a cannonball star, shot out of a star cluster and now moving rapidly through space directly away from the galactic disc.",
"title": "Features"
},
{
"paragraph_id": 18,
"text": "The WZ Sagittae-type dwarf nova DY Canis Minoris (also known as VSX J074727.6+065050) flared up to magnitude 11.4 over January and February 2008 before dropping eight magnitudes to around 19.5 over approximately 80 days. It is a remote binary star system where a white dwarf and low-mass star orbit each other close enough for the former star to draw material off the latter and form an accretion disc. This material builds up until it erupts dramatically.",
"title": "Features"
},
{
"paragraph_id": 19,
"text": "The Milky Way passes through much of Canis Minor, yet it has few deep-sky objects. William Herschel recorded four objects in his 1786 work Catalogue of Nebulae and Clusters of Stars, including two he mistakenly believed were star clusters. NGC 2459 is a group of five thirteenth- and fourteenth-magnitude stars that appear to lie close together in the sky but are not related. A similar situation has occurred with NGC 2394, also in Canis Minor. This is a collection of fifteen unrelated stars of ninth magnitude and fainter.",
"title": "Features"
},
{
"paragraph_id": 20,
"text": "Herschel also observed three faint galaxies, two of which are interacting with each other. NGC 2508 is a lenticular galaxy of thirteenth magnitude, estimated at 205 million light-years' distance (63 million parsecs) with a diameter of 80,000 light-years (25,000 parsecs). Named as a single object by Herschel, NGC 2402 is actually a pair of near-adjacent galaxies that appear to be interacting with each other. Only of fourteenth and fifteenth magnitudes, respectively, the elliptical and spiral galaxy are thought to be approximately 245 million light-years distant, and each measure 55,000 light-years in diameter.",
"title": "Features"
},
{
"paragraph_id": 21,
"text": "The 11 Canis-Minorids, also called the Beta Canis Minorids, are a meteor shower that arise near the fifth-magnitude star 11 Canis Minoris and were discovered in 1964 by Keith Hindley, who investigated their trajectory and proposed a common origin with the comet D/1917 F1 Mellish. However, this conclusion has been refuted subsequently as the number of orbits analysed was low and their trajectories too disparate to confirm a link. They last from 4 to 15 December, peaking over 10 and 11 December.",
"title": "Features"
}
] | Canis Minor is a small constellation in the northern celestial hemisphere. In the second century, it was included as an asterism, or pattern, of two stars in Ptolemy's 48 constellations, and it is counted among the 88 modern constellations. Its name is Latin for "lesser dog", in contrast to Canis Major, the "greater dog"; both figures are commonly represented as following the constellation of Orion the hunter. Canis Minor contains only two stars brighter than the fourth magnitude, Procyon, with a magnitude of 0.34, and Gomeisa, with a magnitude of 2.9. The constellation's dimmer stars were noted by Johann Bayer, who named eight stars including Alpha and Beta, and John Flamsteed, who numbered fourteen. Procyon is the eighth-brightest star in the night sky, as well as one of the closest. A yellow-white main-sequence star, it has a white dwarf companion. Gomeisa is a blue-white main-sequence star. Luyten's Star is a ninth-magnitude red dwarf and the Solar System's next closest stellar neighbour in the constellation after Procyon. Additionally, Procyon and Luyten's Star are only 1.12 light-years away from each other, and Procyon would be the brightest star in Luyten's Star's sky. The fourth-magnitude HD 66141, which has evolved into an orange giant towards the end of its life cycle, was discovered to have a planet in 2012. There are two faint deep-sky objects within the constellation's borders. The 11 Canis-Minorids are a meteor shower that can be seen in early December. | 2001-09-16T20:02:10Z | 2023-12-22T05:20:02Z | [
"Template:Constellations",
"Template:Use British English",
"Template:RA",
"Template:Convert",
"Template:Cite DR2",
"Template:ISBN",
"Template:Stars of Canis Minor",
"Template:Featured article",
"Template:Dec",
"Template:See also",
"Template:Reflist",
"Template:Portal bar",
"Template:Authority control",
"Template:Sky",
"Template:Use dmy dates",
"Template:IPAc-en",
"Template:Cite web",
"Template:Commons and category",
"Template:Cite book",
"Template:Short description",
"Template:Infobox constellation",
"Template:Sfn",
"Template:Cite journal"
] | https://en.wikipedia.org/wiki/Canis_Minor |
6,371 | Centaurus | Centaurus /sɛnˈtɔːrəs, -ˈtɑːr-/ is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. In Greek mythology, Centaurus represents a centaur; a creature that is half human, half horse (another constellation named after a centaur is one from the zodiac: Sagittarius). Notable stars include Alpha Centauri, the nearest star system to the Solar System, its neighbour in the sky Beta Centauri, and V766 Centauri, one of the largest stars yet discovered. The constellation also contains Omega Centauri, the brightest globular cluster as visible from Earth and the largest identified in the Milky Way, possibly a remnant of a dwarf galaxy.
Centaurus contains several very bright stars. Its alpha and beta stars are used as "pointer stars" to help observers find the constellation Crux. Centaurus has 281 stars above magnitude 6.5, meaning that they are visible to the unaided eye, the most of any constellation. Alpha Centauri, the closest star system to the Sun, has a high proper motion; it will be a mere half-degree from Beta Centauri in approximately 4000 years.
Alpha Centauri is a triple star system composed of a binary system orbited by Proxima Centauri, currently the nearest star to the Sun. Traditionally called Rigil Kentaurus (from Arabic رجل قنطورس, meaning "foot of the centaur") or Toliman (from Arabic الظليمين meaning "two male ostriches"), the system has an overall magnitude of −0.28 and is 4.4 light-years from Earth. The primary and secondary are both yellow-hued stars; the first is of magnitude −0.01 and the second: 1.35. Proxima, the tertiary star, is a red dwarf of magnitude 11.0; it appears almost 2 degrees away from the close pairing of Alpha and has a period of approximately one million years. Also a flare star, Proxima has minutes-long outbursts where it brightens by over a magnitude. The Alpha couple revolve in 80-year periodicity and will next appear closest as seen from Earth's telescopes in 2037 and 2038, together as they appear to the naked eye they present the third-brightest "star" in the night sky.
One other first magnitude star Beta Centauri is in the constellation in a position beyond Proxima and toward the narrow axis of Crux, thus with Alpha forming a far-south limb of the constellation. Also called Hadar and Agena, it is a double star; the primary is a blue-hued giant star of magnitude 0.6, 525 light-years from Earth. The secondary is of magnitude 4.0 and has a modest separation, appearing only under intense magnification due to its distance.
The northerly star Theta Centauri, officially named Menkent, is an orange giant star of magnitude 2.06. It is the only bright star of Centaurus that is easily visible from mid-northern latitudes.
The next bright object is Gamma Centauri, a binary star which appears to the naked eye at magnitude 2.2. The primary and secondary are both blue-white hued stars of magnitude 2.9; their period is 84 years.
Centaurus also has many dimmer double stars and binary stars. 3 Centauri is a double star with a blue-white hued primary of magnitude 4.5 and a secondary of magnitude 6.0. The primary is 344 light-years away.
Centaurus is home to many variable stars. R Centauri is a Mira variable star with a minimum magnitude of 11.8 and a maximum magnitude of 5.3; it is about 1,250 light-years from Earth and has a period of 18 months. V810 Centauri is a semiregular variable.
BPM 37093 is a white dwarf star whose carbon atoms are thought to have formed a crystalline structure. Since diamond also consists of carbon arranged in a crystalline lattice (though of a different configuration), scientists have nicknamed this star "Lucy" after the Beatles song "Lucy in the Sky with Diamonds."
PDS 70, (V1032 Centauri) a low mass T Tauri star is found in the constellation Centaurus. In July 2018 astronomers captured the first conclusive image of a protoplanetary disk containing a nascent exoplanet, named PDS 70b.
ω Centauri (NGC 5139), despite being listed as the constellation's "omega" star, is in fact a naked-eye globular cluster, 17,000 light-years away with a diameter of 150 light-years. It is the largest and brightest globular cluster in the Milky Way; at ten times the size of the next-largest cluster, it has a magnitude of 3.7. It is also the most luminous globular cluster in the Milky Way, at over one million solar luminosities. Omega Centauri is classified as a Shapley class VIII cluster, which means that its center is loosely concentrated. It is also one of two only globular clusters to be designated with a Bayer letter; the globular cluster 47 Tucanae (Xi Tucanae) is the only one designated with a Flamsteed number. It contains several million stars, most of which are yellow dwarf stars, but also possesses red giants and blue-white stars; the stars have an average age of 12 billion years. This has prompted suspicion that Omega Centauri was the core of a dwarf galaxy that had been absorbed by the Milky Way. Omega Centauri was determined to be nonstellar in 1677 by the English astronomer Edmond Halley, though it was visible as a star to the ancients. Its status as a globular cluster was determined by James Dunlop in 1827. To the unaided eye, Omega Centauri appears fuzzy and is obviously non-circular; it is approximately half a degree in diameter, the same size as the full Moon.
Centaurus is also home to open clusters. NGC 3766 is an open cluster 6,300 light-years from Earth that is visible to the unaided eye. It contains approximately 100 stars, the brightest of which are 7th magnitude. NGC 5460 is another naked-eye open cluster, 2,300 light-years from Earth, that has an overall magnitude of 6 and contains approximately 40 stars.
There is one bright planetary nebula in Centaurus, NGC 3918, also known as the Blue Planetary. It has an overall magnitude of 8.0 and a central star of magnitude 11.0; it is 2600 light-years from Earth. The Blue Planetary was discovered by John Herschel and named for its color's similarity to Uranus, though the nebula is apparently three times larger than the planet.
Centaurus is rich in galaxies as well. NGC 4622 is a face-on spiral galaxy located 200 million light-years from Earth (redshift 0.0146). Its spiral arms wind in both directions, which makes it nearly impossible for astronomers to determine the rotation of the galaxy. Astronomers theorize that a collision with a smaller companion galaxy near the core of the main galaxy could have led to the unusual spiral structure. NGC 5253, a peculiar irregular galaxy, is located near the border with Hydra and M83, with which it likely had a close gravitational interaction 1–2 billion years ago. This may have sparked the galaxy's high rate of star formation, which continues today and contributes to its high surface brightness. NGC 5253 includes a large nebula and at least 12 large star clusters. In the eyepiece, it is a small galaxy of magnitude 10 with dimensions of 5 arcminutes by 2 arcminutes and a bright nucleus. NGC 4945 is a spiral galaxy seen edge-on from Earth, 13 million light-years away. It is visible with any amateur telescope, as well as binoculars under good conditions; it has been described as "shaped like a candle flame", being long and thin (16' by 3'). In the eyepiece of a large telescope, its southeastern dust lane becomes visible. Another galaxy is NGC 5102, found by star-hopping from Iota Centauri. In the eyepiece, it appears as an elliptical object 9 arcminutes by 2.5 arcminutes tilted on a southwest-northeast axis.
One of the closest active galaxies to Earth is the Centaurus A galaxy, NGC 5128, at 11 million light-years away (redshift 0.00183). It has a supermassive black hole at its core, which expels massive jets of matter that emit radio waves due to synchrotron radiation. Astronomers posit that its dust lanes, not common in elliptical galaxies, are due to a previous merger with another galaxy, probably a spiral galaxy. NGC 5128 appears in the optical spectrum as a fairly large elliptical galaxy with a prominent dust lane. Its overall magnitude is 7.0 and it has been seen under perfect conditions with the naked eye, making it one of the most distant objects visible to the unaided observer. In equatorial and southern latitudes, it is easily found by star hopping from Omega Centauri. In small telescopes, the dust lane is not visible; it begins to appear with about 4 inches of aperture under good conditions. In large amateur instruments, above about 12 inches in aperture, the dust lane's west-northwest to east-southeast direction is easily discerned. Another dim dust lane on the east side of the 12-arcminute-by-15-arcminute galaxy is also visible. ESO 270-17, also called the Fourcade-Figueroa Object, is a low-surface brightness object believed to be the remnants of a galaxy; it does not have a core and is very difficult to observe with an amateur telescope. It measures 7 arcminutes by 1 arcminute. It likely originated as a spiral galaxy and underwent a catastrophic gravitational interaction with Centaurus A around 500 million years ago, stopping its rotation and destroying its structure.
NGC 4650A is a polar-ring galaxy 136 million light-years from Earth (redshift 0.01). It has a central core made of older stars that resembles an elliptical galaxy, and an outer ring of young stars that orbits around the core. The plane of the outer ring is distorted, which suggests that NGC 4650A is the result of a galaxy collision about a billion years ago. This galaxy has also been cited in studies of dark matter, because the stars in the outer ring orbit too quickly for their collective mass. This suggests that the galaxy is surrounded by a dark matter halo, which provides the necessary mass.
One of the closest galaxy clusters to Earth is the Centaurus Cluster at c. 160 million light-years away, having redshift 0.0114. It has a cooler, denser central region of gas and a hotter, more diffuse outer region. The intracluster medium in the Centaurus Cluster has a high concentration of metals (elements heavier than helium) due to a large number of supernovae. This cluster also possesses a plume of gas whose origin is unknown.
While Centaurus now has a high southern latitude, at the dawn of civilization it was an equatorial constellation. Precession has been slowly shifting it southward for millennia, and it is now close to its maximal southern declination. In a little over 7000 years it will be at maximum visibility for those in the northern hemisphere, visible at times in the year up to quite a high northern latitude. The figure of Centaurus can be traced back to a Babylonian constellation known as the Bison-man (MUL.GUD.ALIM). This being was depicted in two major forms: firstly, as a 4-legged bison with a human head, and secondly, as a being with a man's head and torso attached to the rear legs and tail of a bull or bison. It has been closely associated with the Sun god Utu-Shamash from very early times.
The Greeks depicted the constellation as a centaur and gave it its current name. It was mentioned by Eudoxus in the 4th century BC and Aratus in the 3rd century BC. In the 2nd century AD, Claudius Ptolemy catalogued 37 stars in Centaurus, including Alpha Centauri. Large as it is now, in earlier times it was even larger, as the constellation Lupus was treated as an asterism within Centaurus, portrayed in illustrations as an unspecified animal either in the centaur's grasp or impaled on its spear. The Southern Cross, which is now regarded as a separate constellation, was treated by the ancients as a mere asterism formed of the stars composing the centaur's legs. Additionally, what is now the minor constellation Circinus was treated as undefined stars under the centaur's front hooves.
According to the Roman poet Ovid (Fasti v.379), the constellation honors the centaur Chiron, who was tutor to many of the earlier Greek heroes including Heracles (Hercules), Theseus, and Jason, the leader of the Argonauts. It is not to be confused with the more warlike centaur represented by the zodiacal constellation Sagittarius. The legend associated with Chiron says that he was accidentally poisoned with an arrow shot by Hercules, and was subsequently placed in the heavens.
In Chinese astronomy, the stars of Centaurus are found in three areas: the Azure Dragon of the East (東方青龍, Dōng Fāng Qīng Lóng), the Vermillion Bird of the South (南方朱雀, Nán Fāng Zhū Què), and the Southern Asterisms (近南極星區, Jìnnánjíxīngōu). Not all of the stars of Centaurus can be seen from China, and the unseen stars were classified among the Southern Asterisms by Xu Guangqi, based on his study of western star charts. However, most of the brightest stars of Centaurus, including α Centauri, θ Centauri (or Menkent), ε Centauri and η Centauri, can be seen in the Chinese sky.
Some Polynesian peoples considered the stars of Centaurus to be a constellation as well. On Pukapuka, Centaurus had two names: Na Mata-o-te-tokolua and Na Lua-mata-o-Wua-ma-Velo. In Tonga, the constellation was called by four names: O-nga-tangata, Tautanga-ufi, Mamangi-Halahu, and Mau-kuo-mau. Alpha and Beta Centauri were not named specifically by the people of Pukapuka or Tonga, but they were named by the people of Hawaii and the Tuamotus. In Hawaii, the name for Alpha Centauri was either Melemele or Ka Maile-hope and the name for Beta Centauri was either Polapola or Ka Maile-mua. In the Tuamotu islands, Alpha was called Na Kuhi and Beta was called Tere.
The Pointer (α Centauri and β Centauri) is one of the asterisms used by Bugis sailors for navigation, called bintoéng balué, meaning "the widowed-before-marriage". It is also called bintoéng sallatang meaning "southern star".
Two United States Navy ships, USS Centaurus (AKA-17) and USS Centaurus (AK-264), were named after Centaurus, the constellation. | [
{
"paragraph_id": 0,
"text": "Centaurus /sɛnˈtɔːrəs, -ˈtɑːr-/ is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. In Greek mythology, Centaurus represents a centaur; a creature that is half human, half horse (another constellation named after a centaur is one from the zodiac: Sagittarius). Notable stars include Alpha Centauri, the nearest star system to the Solar System, its neighbour in the sky Beta Centauri, and V766 Centauri, one of the largest stars yet discovered. The constellation also contains Omega Centauri, the brightest globular cluster as visible from Earth and the largest identified in the Milky Way, possibly a remnant of a dwarf galaxy.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Centaurus contains several very bright stars. Its alpha and beta stars are used as \"pointer stars\" to help observers find the constellation Crux. Centaurus has 281 stars above magnitude 6.5, meaning that they are visible to the unaided eye, the most of any constellation. Alpha Centauri, the closest star system to the Sun, has a high proper motion; it will be a mere half-degree from Beta Centauri in approximately 4000 years.",
"title": "Notable features"
},
{
"paragraph_id": 2,
"text": "Alpha Centauri is a triple star system composed of a binary system orbited by Proxima Centauri, currently the nearest star to the Sun. Traditionally called Rigil Kentaurus (from Arabic رجل قنطورس, meaning \"foot of the centaur\") or Toliman (from Arabic الظليمين meaning \"two male ostriches\"), the system has an overall magnitude of −0.28 and is 4.4 light-years from Earth. The primary and secondary are both yellow-hued stars; the first is of magnitude −0.01 and the second: 1.35. Proxima, the tertiary star, is a red dwarf of magnitude 11.0; it appears almost 2 degrees away from the close pairing of Alpha and has a period of approximately one million years. Also a flare star, Proxima has minutes-long outbursts where it brightens by over a magnitude. The Alpha couple revolve in 80-year periodicity and will next appear closest as seen from Earth's telescopes in 2037 and 2038, together as they appear to the naked eye they present the third-brightest \"star\" in the night sky.",
"title": "Notable features"
},
{
"paragraph_id": 3,
"text": "One other first magnitude star Beta Centauri is in the constellation in a position beyond Proxima and toward the narrow axis of Crux, thus with Alpha forming a far-south limb of the constellation. Also called Hadar and Agena, it is a double star; the primary is a blue-hued giant star of magnitude 0.6, 525 light-years from Earth. The secondary is of magnitude 4.0 and has a modest separation, appearing only under intense magnification due to its distance.",
"title": "Notable features"
},
{
"paragraph_id": 4,
"text": "The northerly star Theta Centauri, officially named Menkent, is an orange giant star of magnitude 2.06. It is the only bright star of Centaurus that is easily visible from mid-northern latitudes.",
"title": "Notable features"
},
{
"paragraph_id": 5,
"text": "The next bright object is Gamma Centauri, a binary star which appears to the naked eye at magnitude 2.2. The primary and secondary are both blue-white hued stars of magnitude 2.9; their period is 84 years.",
"title": "Notable features"
},
{
"paragraph_id": 6,
"text": "Centaurus also has many dimmer double stars and binary stars. 3 Centauri is a double star with a blue-white hued primary of magnitude 4.5 and a secondary of magnitude 6.0. The primary is 344 light-years away.",
"title": "Notable features"
},
{
"paragraph_id": 7,
"text": "Centaurus is home to many variable stars. R Centauri is a Mira variable star with a minimum magnitude of 11.8 and a maximum magnitude of 5.3; it is about 1,250 light-years from Earth and has a period of 18 months. V810 Centauri is a semiregular variable.",
"title": "Notable features"
},
{
"paragraph_id": 8,
"text": "BPM 37093 is a white dwarf star whose carbon atoms are thought to have formed a crystalline structure. Since diamond also consists of carbon arranged in a crystalline lattice (though of a different configuration), scientists have nicknamed this star \"Lucy\" after the Beatles song \"Lucy in the Sky with Diamonds.\"",
"title": "Notable features"
},
{
"paragraph_id": 9,
"text": "PDS 70, (V1032 Centauri) a low mass T Tauri star is found in the constellation Centaurus. In July 2018 astronomers captured the first conclusive image of a protoplanetary disk containing a nascent exoplanet, named PDS 70b.",
"title": "Notable features"
},
{
"paragraph_id": 10,
"text": "ω Centauri (NGC 5139), despite being listed as the constellation's \"omega\" star, is in fact a naked-eye globular cluster, 17,000 light-years away with a diameter of 150 light-years. It is the largest and brightest globular cluster in the Milky Way; at ten times the size of the next-largest cluster, it has a magnitude of 3.7. It is also the most luminous globular cluster in the Milky Way, at over one million solar luminosities. Omega Centauri is classified as a Shapley class VIII cluster, which means that its center is loosely concentrated. It is also one of two only globular clusters to be designated with a Bayer letter; the globular cluster 47 Tucanae (Xi Tucanae) is the only one designated with a Flamsteed number. It contains several million stars, most of which are yellow dwarf stars, but also possesses red giants and blue-white stars; the stars have an average age of 12 billion years. This has prompted suspicion that Omega Centauri was the core of a dwarf galaxy that had been absorbed by the Milky Way. Omega Centauri was determined to be nonstellar in 1677 by the English astronomer Edmond Halley, though it was visible as a star to the ancients. Its status as a globular cluster was determined by James Dunlop in 1827. To the unaided eye, Omega Centauri appears fuzzy and is obviously non-circular; it is approximately half a degree in diameter, the same size as the full Moon.",
"title": "Notable features"
},
{
"paragraph_id": 11,
"text": "Centaurus is also home to open clusters. NGC 3766 is an open cluster 6,300 light-years from Earth that is visible to the unaided eye. It contains approximately 100 stars, the brightest of which are 7th magnitude. NGC 5460 is another naked-eye open cluster, 2,300 light-years from Earth, that has an overall magnitude of 6 and contains approximately 40 stars.",
"title": "Notable features"
},
{
"paragraph_id": 12,
"text": "There is one bright planetary nebula in Centaurus, NGC 3918, also known as the Blue Planetary. It has an overall magnitude of 8.0 and a central star of magnitude 11.0; it is 2600 light-years from Earth. The Blue Planetary was discovered by John Herschel and named for its color's similarity to Uranus, though the nebula is apparently three times larger than the planet.",
"title": "Notable features"
},
{
"paragraph_id": 13,
"text": "Centaurus is rich in galaxies as well. NGC 4622 is a face-on spiral galaxy located 200 million light-years from Earth (redshift 0.0146). Its spiral arms wind in both directions, which makes it nearly impossible for astronomers to determine the rotation of the galaxy. Astronomers theorize that a collision with a smaller companion galaxy near the core of the main galaxy could have led to the unusual spiral structure. NGC 5253, a peculiar irregular galaxy, is located near the border with Hydra and M83, with which it likely had a close gravitational interaction 1–2 billion years ago. This may have sparked the galaxy's high rate of star formation, which continues today and contributes to its high surface brightness. NGC 5253 includes a large nebula and at least 12 large star clusters. In the eyepiece, it is a small galaxy of magnitude 10 with dimensions of 5 arcminutes by 2 arcminutes and a bright nucleus. NGC 4945 is a spiral galaxy seen edge-on from Earth, 13 million light-years away. It is visible with any amateur telescope, as well as binoculars under good conditions; it has been described as \"shaped like a candle flame\", being long and thin (16' by 3'). In the eyepiece of a large telescope, its southeastern dust lane becomes visible. Another galaxy is NGC 5102, found by star-hopping from Iota Centauri. In the eyepiece, it appears as an elliptical object 9 arcminutes by 2.5 arcminutes tilted on a southwest-northeast axis.",
"title": "Notable features"
},
{
"paragraph_id": 14,
"text": "One of the closest active galaxies to Earth is the Centaurus A galaxy, NGC 5128, at 11 million light-years away (redshift 0.00183). It has a supermassive black hole at its core, which expels massive jets of matter that emit radio waves due to synchrotron radiation. Astronomers posit that its dust lanes, not common in elliptical galaxies, are due to a previous merger with another galaxy, probably a spiral galaxy. NGC 5128 appears in the optical spectrum as a fairly large elliptical galaxy with a prominent dust lane. Its overall magnitude is 7.0 and it has been seen under perfect conditions with the naked eye, making it one of the most distant objects visible to the unaided observer. In equatorial and southern latitudes, it is easily found by star hopping from Omega Centauri. In small telescopes, the dust lane is not visible; it begins to appear with about 4 inches of aperture under good conditions. In large amateur instruments, above about 12 inches in aperture, the dust lane's west-northwest to east-southeast direction is easily discerned. Another dim dust lane on the east side of the 12-arcminute-by-15-arcminute galaxy is also visible. ESO 270-17, also called the Fourcade-Figueroa Object, is a low-surface brightness object believed to be the remnants of a galaxy; it does not have a core and is very difficult to observe with an amateur telescope. It measures 7 arcminutes by 1 arcminute. It likely originated as a spiral galaxy and underwent a catastrophic gravitational interaction with Centaurus A around 500 million years ago, stopping its rotation and destroying its structure.",
"title": "Notable features"
},
{
"paragraph_id": 15,
"text": "NGC 4650A is a polar-ring galaxy 136 million light-years from Earth (redshift 0.01). It has a central core made of older stars that resembles an elliptical galaxy, and an outer ring of young stars that orbits around the core. The plane of the outer ring is distorted, which suggests that NGC 4650A is the result of a galaxy collision about a billion years ago. This galaxy has also been cited in studies of dark matter, because the stars in the outer ring orbit too quickly for their collective mass. This suggests that the galaxy is surrounded by a dark matter halo, which provides the necessary mass.",
"title": "Notable features"
},
{
"paragraph_id": 16,
"text": "One of the closest galaxy clusters to Earth is the Centaurus Cluster at c. 160 million light-years away, having redshift 0.0114. It has a cooler, denser central region of gas and a hotter, more diffuse outer region. The intracluster medium in the Centaurus Cluster has a high concentration of metals (elements heavier than helium) due to a large number of supernovae. This cluster also possesses a plume of gas whose origin is unknown.",
"title": "Notable features"
},
{
"paragraph_id": 17,
"text": "While Centaurus now has a high southern latitude, at the dawn of civilization it was an equatorial constellation. Precession has been slowly shifting it southward for millennia, and it is now close to its maximal southern declination. In a little over 7000 years it will be at maximum visibility for those in the northern hemisphere, visible at times in the year up to quite a high northern latitude. The figure of Centaurus can be traced back to a Babylonian constellation known as the Bison-man (MUL.GUD.ALIM). This being was depicted in two major forms: firstly, as a 4-legged bison with a human head, and secondly, as a being with a man's head and torso attached to the rear legs and tail of a bull or bison. It has been closely associated with the Sun god Utu-Shamash from very early times.",
"title": "History"
},
{
"paragraph_id": 18,
"text": "The Greeks depicted the constellation as a centaur and gave it its current name. It was mentioned by Eudoxus in the 4th century BC and Aratus in the 3rd century BC. In the 2nd century AD, Claudius Ptolemy catalogued 37 stars in Centaurus, including Alpha Centauri. Large as it is now, in earlier times it was even larger, as the constellation Lupus was treated as an asterism within Centaurus, portrayed in illustrations as an unspecified animal either in the centaur's grasp or impaled on its spear. The Southern Cross, which is now regarded as a separate constellation, was treated by the ancients as a mere asterism formed of the stars composing the centaur's legs. Additionally, what is now the minor constellation Circinus was treated as undefined stars under the centaur's front hooves.",
"title": "History"
},
{
"paragraph_id": 19,
"text": "According to the Roman poet Ovid (Fasti v.379), the constellation honors the centaur Chiron, who was tutor to many of the earlier Greek heroes including Heracles (Hercules), Theseus, and Jason, the leader of the Argonauts. It is not to be confused with the more warlike centaur represented by the zodiacal constellation Sagittarius. The legend associated with Chiron says that he was accidentally poisoned with an arrow shot by Hercules, and was subsequently placed in the heavens.",
"title": "History"
},
{
"paragraph_id": 20,
"text": "In Chinese astronomy, the stars of Centaurus are found in three areas: the Azure Dragon of the East (東方青龍, Dōng Fāng Qīng Lóng), the Vermillion Bird of the South (南方朱雀, Nán Fāng Zhū Què), and the Southern Asterisms (近南極星區, Jìnnánjíxīngōu). Not all of the stars of Centaurus can be seen from China, and the unseen stars were classified among the Southern Asterisms by Xu Guangqi, based on his study of western star charts. However, most of the brightest stars of Centaurus, including α Centauri, θ Centauri (or Menkent), ε Centauri and η Centauri, can be seen in the Chinese sky.",
"title": "Equivalents"
},
{
"paragraph_id": 21,
"text": "Some Polynesian peoples considered the stars of Centaurus to be a constellation as well. On Pukapuka, Centaurus had two names: Na Mata-o-te-tokolua and Na Lua-mata-o-Wua-ma-Velo. In Tonga, the constellation was called by four names: O-nga-tangata, Tautanga-ufi, Mamangi-Halahu, and Mau-kuo-mau. Alpha and Beta Centauri were not named specifically by the people of Pukapuka or Tonga, but they were named by the people of Hawaii and the Tuamotus. In Hawaii, the name for Alpha Centauri was either Melemele or Ka Maile-hope and the name for Beta Centauri was either Polapola or Ka Maile-mua. In the Tuamotu islands, Alpha was called Na Kuhi and Beta was called Tere.",
"title": "Equivalents"
},
{
"paragraph_id": 22,
"text": "The Pointer (α Centauri and β Centauri) is one of the asterisms used by Bugis sailors for navigation, called bintoéng balué, meaning \"the widowed-before-marriage\". It is also called bintoéng sallatang meaning \"southern star\".",
"title": "Equivalents"
},
{
"paragraph_id": 23,
"text": "Two United States Navy ships, USS Centaurus (AKA-17) and USS Centaurus (AK-264), were named after Centaurus, the constellation.",
"title": "Namesakes"
}
] | Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. In Greek mythology, Centaurus represents a centaur; a creature that is half human, half horse. Notable stars include Alpha Centauri, the nearest star system to the Solar System, its neighbour in the sky Beta Centauri, and V766 Centauri, one of the largest stars yet discovered. The constellation also contains Omega Centauri, the brightest globular cluster as visible from Earth and the largest identified in the Milky Way, possibly a remnant of a dwarf galaxy. | 2001-09-16T22:05:24Z | 2023-12-14T02:01:29Z | [
"Template:Reflist",
"Template:Cite book",
"Template:ISBN",
"Template:Commons",
"Template:Portal bar",
"Template:Authority control",
"Template:Cite web",
"Template:Citation",
"Template:Stars of Centaurus",
"Template:Short description",
"Template:IPAc-en",
"Template:Abbreviation",
"Template:Sfn",
"Template:Circa",
"Template:USS",
"Template:Constellations",
"Template:Sky",
"Template:Other uses",
"Template:Infobox constellation",
"Template:See also",
"Template:Cite news",
"Template:Cite journal"
] | https://en.wikipedia.org/wiki/Centaurus |
6,416 | Impact crater | An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Lunar impact craters range from microscopic craters on lunar rocks returned by the Apollo program and small, simple, bowl-shaped depressions in the lunar regolith to large, complex, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth.
Impact craters are the dominant geographic features on many solid Solar System objects including the Moon, Mercury, Callisto, Ganymede and most small moons and asteroids. On other planets and moons that experience more active surface geological processes, such as Earth, Venus, Europa, Io and Titan, visible impact craters are less common because they become eroded, buried or transformed by tectonics over time. Where such processes have destroyed most of the original crater topography, the terms impact structure or astrobleme are more commonly used. In early literature, before the significance of impact cratering was widely recognised, the terms cryptoexplosion or cryptovolcanic structure were often used to describe what are now recognised as impact-related features on Earth.
The cratering records of very old surfaces, such as Mercury, the Moon, and the southern highlands of Mars, record a period of intense early bombardment in the inner Solar System around 3.9 billion years ago. The rate of crater production on Earth has since been considerably lower, but it is appreciable nonetheless. Earth experiences, on average, from one to three impacts large enough to produce a 20-kilometre-diameter (12 mi) crater every million years. This indicates that there should be far more relatively young craters on the planet than have been discovered so far. The cratering rate in the inner solar system fluctuates as a consequence of collisions in the asteroid belt that create a family of fragments that are often sent cascading into the inner solar system. Formed in a collision 80 million years ago, the Baptistina family of asteroids is thought to have caused a large spike in the impact rate. The rate of impact cratering in the outer Solar System could be different from the inner Solar System.
Although Earth's active surface processes quickly destroy the impact record, about 190 terrestrial impact craters have been identified. These range in diameter from a few tens of meters up to about 300 km (190 mi), and they range in age from recent times (e.g. the Sikhote-Alin craters in Russia whose creation was witnessed in 1947) to more than two billion years, though most are less than 500 million years old because geological processes tend to obliterate older craters. They are also selectively found in the stable interior regions of continents. Few undersea craters have been discovered because of the difficulty of surveying the sea floor, the rapid rate of change of the ocean bottom, and the subduction of the ocean floor into Earth's interior by processes of plate tectonics.
Impact craters are not to be confused with landforms that may appear similar, including calderas, sinkholes, glacial cirques, ring dikes, salt domes, and others.
Daniel M. Barringer, a mining engineer, was convinced already in 1903 that the crater he owned, Meteor Crater, was of cosmic origin. Most geologists at the time assumed it formed as the result of a volcanic steam eruption.
In the 1920s, the American geologist Walter H. Bucher studied a number of sites now recognized as impact craters in the United States. He concluded they had been created by some great explosive event, but believed that this force was probably volcanic in origin. However, in 1936, the geologists John D. Boon and Claude C. Albritton Jr. revisited Bucher's studies and concluded that the craters that he studied were probably formed by impacts.
Grove Karl Gilbert suggested in 1893 that the Moon's craters were formed by large asteroid impacts. Ralph Baldwin in 1949 wrote that the Moon's craters were mostly of impact origin. Around 1960, Gene Shoemaker revived the idea. According to David H. Levy, Shoemaker "saw the craters on the Moon as logical impact sites that were formed not gradually, in eons, but explosively, in seconds." For his PhD degree at Princeton University (1960), under the guidance of Harry Hammond Hess, Shoemaker studied the impact dynamics of Meteor Crater. Shoemaker noted that Meteor Crater had the same form and structure as two explosion craters created from atomic bomb tests at the Nevada Test Site, notably Jangle U in 1951 and Teapot Ess in 1955. In 1960, Edward C. T. Chao and Shoemaker identified coesite (a form of silicon dioxide) at Meteor Crater, proving the crater was formed from an impact generating extremely high temperatures and pressures. They followed this discovery with the identification of coesite within suevite at Nördlinger Ries, proving its impact origin.
Armed with the knowledge of shock-metamorphic features, Carlyle S. Beals and colleagues at the Dominion Astrophysical Observatory in Victoria, British Columbia, Canada and Wolf von Engelhardt of the University of Tübingen in Germany began a methodical search for impact craters. By 1970, they had tentatively identified more than 50. Although their work was controversial, the American Apollo Moon landings, which were in progress at the time, provided supportive evidence by recognizing the rate of impact cratering on the Moon. Because the processes of erosion on the Moon are minimal, craters persist. Since the Earth could be expected to have roughly the same cratering rate as the Moon, it became clear that the Earth had suffered far more impacts than could be seen by counting evident craters.
Impact cratering involves high velocity collisions between solid objects, typically much greater than the speed of sound in those objects. Such hyper-velocity impacts produce physical effects such as melting and vaporization that do not occur in familiar sub-sonic collisions. On Earth, ignoring the slowing effects of travel through the atmosphere, the lowest impact velocity with an object from space is equal to the gravitational escape velocity of about 11 km/s. The fastest impacts occur at about 72 km/s in the "worst case" scenario in which an object in a retrograde near-parabolic orbit hits Earth. The median impact velocity on Earth is about 20 km/s.
However, the slowing effects of travel through the atmosphere rapidly decelerate any potential impactor, especially in the lowest 12 kilometres where 90% of the earth's atmospheric mass lies. Meteorites of up to 7,000 kg lose all their cosmic velocity due to atmospheric drag at a certain altitude (retardation point), and start to accelerate again due to Earth's gravity until the body reaches its terminal velocity of 0.09 to 0.16 km/s. The larger the meteoroid (i.e. asteroids and comets) the more of its initial cosmic velocity it preserves. While an object of 9,000 kg maintains about 6% of its original velocity, one of 900,000 kg already preserves about 70%. Extremely large bodies (about 100,000 tonnes) are not slowed by the atmosphere at all, and impact with their initial cosmic velocity if no prior disintegration occurs.
Impacts at these high speeds produce shock waves in solid materials, and both impactor and the material impacted are rapidly compressed to high density. Following initial compression, the high-density, over-compressed region rapidly depressurizes, exploding violently, to set in train the sequence of events that produces the impact crater. Impact-crater formation is therefore more closely analogous to cratering by high explosives than by mechanical displacement. Indeed, the energy density of some material involved in the formation of impact craters is many times higher than that generated by high explosives. Since craters are caused by explosions, they are nearly always circular – only very low-angle impacts cause significantly elliptical craters.
This describes impacts on solid surfaces. Impacts on porous surfaces, such as that of Hyperion, may produce internal compression without ejecta, punching a hole in the surface without filling in nearby craters. This may explain the 'sponge-like' appearance of that moon.
It is convenient to divide the impact process conceptually into three distinct stages: (1) initial contact and compression, (2) excavation, (3) modification and collapse. In practice, there is overlap between the three processes with, for example, the excavation of the crater continuing in some regions while modification and collapse is already underway in others.
In the absence of atmosphere, the impact process begins when the impactor first touches the target surface. This contact accelerates the target and decelerates the impactor. Because the impactor is moving so rapidly, the rear of the object moves a significant distance during the short-but-finite time taken for the deceleration to propagate across the impactor. As a result, the impactor is compressed, its density rises, and the pressure within it increases dramatically. Peak pressures in large impacts exceed 1 T Pa to reach values more usually found deep in the interiors of planets, or generated artificially in nuclear explosions.
In physical terms, a shock wave originates from the point of contact. As this shock wave expands, it decelerates and compresses the impactor, and it accelerates and compresses the target. Stress levels within the shock wave far exceed the strength of solid materials; consequently, both the impactor and the target close to the impact site are irreversibly damaged. Many crystalline minerals can be transformed into higher-density phases by shock waves; for example, the common mineral quartz can be transformed into the higher-pressure forms coesite and stishovite. Many other shock-related changes take place within both impactor and target as the shock wave passes through, and some of these changes can be used as diagnostic tools to determine whether particular geological features were produced by impact cratering.
As the shock wave decays, the shocked region decompresses towards more usual pressures and densities. The damage produced by the shock wave raises the temperature of the material. In all but the smallest impacts this increase in temperature is sufficient to melt the impactor, and in larger impacts to vaporize most of it and to melt large volumes of the target. As well as being heated, the target near the impact is accelerated by the shock wave, and it continues moving away from the impact behind the decaying shock wave.
Contact, compression, decompression, and the passage of the shock wave all occur within a few tenths of a second for a large impact. The subsequent excavation of the crater occurs more slowly, and during this stage the flow of material is largely subsonic. During excavation, the crater grows as the accelerated target material moves away from the point of impact. The target's motion is initially downwards and outwards, but it becomes outwards and upwards. The flow initially produces an approximately hemispherical cavity that continues to grow, eventually producing a paraboloid (bowl-shaped) crater in which the centre has been pushed down, a significant volume of material has been ejected, and a topographically elevated crater rim has been pushed up. When this cavity has reached its maximum size, it is called the transient cavity.
The depth of the transient cavity is typically a quarter to a third of its diameter. Ejecta thrown out of the crater do not include material excavated from the full depth of the transient cavity; typically the depth of maximum excavation is only about a third of the total depth. As a result, about one third of the volume of the transient crater is formed by the ejection of material, and the remaining two thirds is formed by the displacement of material downwards, outwards and upwards, to form the elevated rim. For impacts into highly porous materials, a significant crater volume may also be formed by the permanent compaction of the pore space. Such compaction craters may be important on many asteroids, comets and small moons.
In large impacts, as well as material displaced and ejected to form the crater, significant volumes of target material may be melted and vaporized together with the original impactor. Some of this impact melt rock may be ejected, but most of it remains within the transient crater, initially forming a layer of impact melt coating the interior of the transient cavity. In contrast, the hot dense vaporized material expands rapidly out of the growing cavity, carrying some solid and molten material within it as it does so. As this hot vapor cloud expands, it rises and cools much like the archetypal mushroom cloud generated by large nuclear explosions. In large impacts, the expanding vapor cloud may rise to many times the scale height of the atmosphere, effectively expanding into free space.
Most material ejected from the crater is deposited within a few crater radii, but a small fraction may travel large distances at high velocity, and in large impacts it may exceed escape velocity and leave the impacted planet or moon entirely. The majority of the fastest material is ejected from close to the center of impact, and the slowest material is ejected close to the rim at low velocities to form an overturned coherent flap of ejecta immediately outside the rim. As ejecta escapes from the growing crater, it forms an expanding curtain in the shape of an inverted cone. The trajectory of individual particles within the curtain is thought to be largely ballistic.
Small volumes of un-melted and relatively un-shocked material may be spalled at very high relative velocities from the surface of the target and from the rear of the impactor. Spalling provides a potential mechanism whereby material may be ejected into inter-planetary space largely undamaged, and whereby small volumes of the impactor may be preserved undamaged even in large impacts. Small volumes of high-speed material may also be generated early in the impact by jetting. This occurs when two surfaces converge rapidly and obliquely at a small angle, and high-temperature highly shocked material is expelled from the convergence zone with velocities that may be several times larger than the impact velocity.
In most circumstances, the transient cavity is not stable and collapses under gravity. In small craters, less than about 4 km diameter on Earth, there is some limited collapse of the crater rim coupled with debris sliding down the crater walls and drainage of impact melts into the deeper cavity. The resultant structure is called a simple crater, and it remains bowl-shaped and superficially similar to the transient crater. In simple craters, the original excavation cavity is overlain by a lens of collapse breccia, ejecta and melt rock, and a portion of the central crater floor may sometimes be flat.
Above a certain threshold size, which varies with planetary gravity, the collapse and modification of the transient cavity is much more extensive, and the resulting structure is called a complex crater. The collapse of the transient cavity is driven by gravity, and involves both the uplift of the central region and the inward collapse of the rim. The central uplift is not the result of elastic rebound, which is a process in which a material with elastic strength attempts to return to its original geometry; rather the collapse is a process in which a material with little or no strength attempts to return to a state of gravitational equilibrium.
Complex craters have uplifted centers, and they have typically broad flat shallow crater floors, and terraced walls. At the largest sizes, one or more exterior or interior rings may appear, and the structure may be labeled an impact basin rather than an impact crater. Complex-crater morphology on rocky planets appears to follow a regular sequence with increasing size: small complex craters with a central topographic peak are called central peak craters, for example Tycho; intermediate-sized craters, in which the central peak is replaced by a ring of peaks, are called peak-ring craters, for example Schrödinger; and the largest craters contain multiple concentric topographic rings, and are called multi-ringed basins, for example Orientale. On icy (as opposed to rocky) bodies, other morphological forms appear that may have central pits rather than central peaks, and at the largest sizes may contain many concentric rings. Valhalla on Callisto is an example of this type.
Non-explosive volcanic craters can usually be distinguished from impact craters by their irregular shape and the association of volcanic flows and other volcanic materials. Impact craters produce melted rocks as well, but usually in smaller volumes with different characteristics.
The distinctive mark of an impact crater is the presence of rock that has undergone shock-metamorphic effects, such as shatter cones, melted rocks, and crystal deformations. The problem is that these materials tend to be deeply buried, at least for simple craters. They tend to be revealed in the uplifted center of a complex crater, however.
Impacts produce distinctive shock-metamorphic effects that allow impact sites to be distinctively identified. Such shock-metamorphic effects can include:
On Earth impact craters have resulted in useful minerals. Some of the ores produced from impact related effects on Earth include ores of iron, uranium, gold, copper, and nickel. It is estimated that the value of materials mined from impact structures is five billion dollars/year just for North America. The eventual usefulness of impact craters depends on several factors especially the nature of the materials that were impacted and when the materials were affected. In some cases the deposits were already in place and the impact brought them to the surface. These are called "progenetic economic deposits." Others were created during the actual impact. The great energy involved caused melting. Useful minerals formed as a result of this energy are classified as "syngenetic deposits." The third type, called "epigenetic deposits," is caused by the creation of a basin from the impact. Many of the minerals that our modern lives depend on are associated with impacts in the past. The Vredeford Dome in the center of the Witwatersrand Basin is the largest goldfield in the world which has supplied about 40% of all the gold ever mined in an impact structure (though the gold did not come from the bolide). The asteroid that struck the region was 9.7 km (6 mi) wide. The Sudbury Basin was caused by an impacting body over 9.7 km (6 mi) in diameter. This basin is famous for its deposits of nickel, copper, and platinum group elements. An impact was involved in making the Carswell structure in Saskatchewan, Canada; it contains uranium deposits. Hydrocarbons are common around impact structures. Fifty percent of impact structures in North America in hydrocarbon-bearing sedimentary basins contain oil/gas fields.
Because of the many missions studying Mars since the 1960s, there is good coverage of its surface which contains large numbers of craters. Many of the craters on Mars differ from those on the Moon and other moons since Mars contains ice under the ground, especially in the higher latitudes. Some of the types of craters that have special shapes due to impact into ice-rich ground are pedestal craters, rampart craters, expanded craters, and LARLE craters.
On Earth, the recognition of impact craters is a branch of geology, and is related to planetary geology in the study of other worlds. Out of many proposed craters, relatively few are confirmed. The following twenty are a sample of articles of confirmed and well-documented impact sites.
See the Earth Impact Database, a website concerned with 190 (as of July 2019) scientifically-confirmed impact craters on Earth.
There are approximately twelve more impact craters/basins larger than 300 km on the Moon, five on Mercury, and four on Mars. Large basins, some unnamed but mostly smaller than 300 km, can also be found on Saturn's moons Dione, Rhea and Iapetus. | [
{
"paragraph_id": 0,
"text": "An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Lunar impact craters range from microscopic craters on lunar rocks returned by the Apollo program and small, simple, bowl-shaped depressions in the lunar regolith to large, complex, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Impact craters are the dominant geographic features on many solid Solar System objects including the Moon, Mercury, Callisto, Ganymede and most small moons and asteroids. On other planets and moons that experience more active surface geological processes, such as Earth, Venus, Europa, Io and Titan, visible impact craters are less common because they become eroded, buried or transformed by tectonics over time. Where such processes have destroyed most of the original crater topography, the terms impact structure or astrobleme are more commonly used. In early literature, before the significance of impact cratering was widely recognised, the terms cryptoexplosion or cryptovolcanic structure were often used to describe what are now recognised as impact-related features on Earth.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The cratering records of very old surfaces, such as Mercury, the Moon, and the southern highlands of Mars, record a period of intense early bombardment in the inner Solar System around 3.9 billion years ago. The rate of crater production on Earth has since been considerably lower, but it is appreciable nonetheless. Earth experiences, on average, from one to three impacts large enough to produce a 20-kilometre-diameter (12 mi) crater every million years. This indicates that there should be far more relatively young craters on the planet than have been discovered so far. The cratering rate in the inner solar system fluctuates as a consequence of collisions in the asteroid belt that create a family of fragments that are often sent cascading into the inner solar system. Formed in a collision 80 million years ago, the Baptistina family of asteroids is thought to have caused a large spike in the impact rate. The rate of impact cratering in the outer Solar System could be different from the inner Solar System.",
"title": ""
},
{
"paragraph_id": 3,
"text": "Although Earth's active surface processes quickly destroy the impact record, about 190 terrestrial impact craters have been identified. These range in diameter from a few tens of meters up to about 300 km (190 mi), and they range in age from recent times (e.g. the Sikhote-Alin craters in Russia whose creation was witnessed in 1947) to more than two billion years, though most are less than 500 million years old because geological processes tend to obliterate older craters. They are also selectively found in the stable interior regions of continents. Few undersea craters have been discovered because of the difficulty of surveying the sea floor, the rapid rate of change of the ocean bottom, and the subduction of the ocean floor into Earth's interior by processes of plate tectonics.",
"title": ""
},
{
"paragraph_id": 4,
"text": "Impact craters are not to be confused with landforms that may appear similar, including calderas, sinkholes, glacial cirques, ring dikes, salt domes, and others.",
"title": ""
},
{
"paragraph_id": 5,
"text": "Daniel M. Barringer, a mining engineer, was convinced already in 1903 that the crater he owned, Meteor Crater, was of cosmic origin. Most geologists at the time assumed it formed as the result of a volcanic steam eruption.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "In the 1920s, the American geologist Walter H. Bucher studied a number of sites now recognized as impact craters in the United States. He concluded they had been created by some great explosive event, but believed that this force was probably volcanic in origin. However, in 1936, the geologists John D. Boon and Claude C. Albritton Jr. revisited Bucher's studies and concluded that the craters that he studied were probably formed by impacts.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "Grove Karl Gilbert suggested in 1893 that the Moon's craters were formed by large asteroid impacts. Ralph Baldwin in 1949 wrote that the Moon's craters were mostly of impact origin. Around 1960, Gene Shoemaker revived the idea. According to David H. Levy, Shoemaker \"saw the craters on the Moon as logical impact sites that were formed not gradually, in eons, but explosively, in seconds.\" For his PhD degree at Princeton University (1960), under the guidance of Harry Hammond Hess, Shoemaker studied the impact dynamics of Meteor Crater. Shoemaker noted that Meteor Crater had the same form and structure as two explosion craters created from atomic bomb tests at the Nevada Test Site, notably Jangle U in 1951 and Teapot Ess in 1955. In 1960, Edward C. T. Chao and Shoemaker identified coesite (a form of silicon dioxide) at Meteor Crater, proving the crater was formed from an impact generating extremely high temperatures and pressures. They followed this discovery with the identification of coesite within suevite at Nördlinger Ries, proving its impact origin.",
"title": "History"
},
{
"paragraph_id": 8,
"text": "Armed with the knowledge of shock-metamorphic features, Carlyle S. Beals and colleagues at the Dominion Astrophysical Observatory in Victoria, British Columbia, Canada and Wolf von Engelhardt of the University of Tübingen in Germany began a methodical search for impact craters. By 1970, they had tentatively identified more than 50. Although their work was controversial, the American Apollo Moon landings, which were in progress at the time, provided supportive evidence by recognizing the rate of impact cratering on the Moon. Because the processes of erosion on the Moon are minimal, craters persist. Since the Earth could be expected to have roughly the same cratering rate as the Moon, it became clear that the Earth had suffered far more impacts than could be seen by counting evident craters.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "Impact cratering involves high velocity collisions between solid objects, typically much greater than the speed of sound in those objects. Such hyper-velocity impacts produce physical effects such as melting and vaporization that do not occur in familiar sub-sonic collisions. On Earth, ignoring the slowing effects of travel through the atmosphere, the lowest impact velocity with an object from space is equal to the gravitational escape velocity of about 11 km/s. The fastest impacts occur at about 72 km/s in the \"worst case\" scenario in which an object in a retrograde near-parabolic orbit hits Earth. The median impact velocity on Earth is about 20 km/s.",
"title": "Crater formation"
},
{
"paragraph_id": 10,
"text": "However, the slowing effects of travel through the atmosphere rapidly decelerate any potential impactor, especially in the lowest 12 kilometres where 90% of the earth's atmospheric mass lies. Meteorites of up to 7,000 kg lose all their cosmic velocity due to atmospheric drag at a certain altitude (retardation point), and start to accelerate again due to Earth's gravity until the body reaches its terminal velocity of 0.09 to 0.16 km/s. The larger the meteoroid (i.e. asteroids and comets) the more of its initial cosmic velocity it preserves. While an object of 9,000 kg maintains about 6% of its original velocity, one of 900,000 kg already preserves about 70%. Extremely large bodies (about 100,000 tonnes) are not slowed by the atmosphere at all, and impact with their initial cosmic velocity if no prior disintegration occurs.",
"title": "Crater formation"
},
{
"paragraph_id": 11,
"text": "Impacts at these high speeds produce shock waves in solid materials, and both impactor and the material impacted are rapidly compressed to high density. Following initial compression, the high-density, over-compressed region rapidly depressurizes, exploding violently, to set in train the sequence of events that produces the impact crater. Impact-crater formation is therefore more closely analogous to cratering by high explosives than by mechanical displacement. Indeed, the energy density of some material involved in the formation of impact craters is many times higher than that generated by high explosives. Since craters are caused by explosions, they are nearly always circular – only very low-angle impacts cause significantly elliptical craters.",
"title": "Crater formation"
},
{
"paragraph_id": 12,
"text": "This describes impacts on solid surfaces. Impacts on porous surfaces, such as that of Hyperion, may produce internal compression without ejecta, punching a hole in the surface without filling in nearby craters. This may explain the 'sponge-like' appearance of that moon.",
"title": "Crater formation"
},
{
"paragraph_id": 13,
"text": "It is convenient to divide the impact process conceptually into three distinct stages: (1) initial contact and compression, (2) excavation, (3) modification and collapse. In practice, there is overlap between the three processes with, for example, the excavation of the crater continuing in some regions while modification and collapse is already underway in others.",
"title": "Crater formation"
},
{
"paragraph_id": 14,
"text": "In the absence of atmosphere, the impact process begins when the impactor first touches the target surface. This contact accelerates the target and decelerates the impactor. Because the impactor is moving so rapidly, the rear of the object moves a significant distance during the short-but-finite time taken for the deceleration to propagate across the impactor. As a result, the impactor is compressed, its density rises, and the pressure within it increases dramatically. Peak pressures in large impacts exceed 1 T Pa to reach values more usually found deep in the interiors of planets, or generated artificially in nuclear explosions.",
"title": "Crater formation"
},
{
"paragraph_id": 15,
"text": "In physical terms, a shock wave originates from the point of contact. As this shock wave expands, it decelerates and compresses the impactor, and it accelerates and compresses the target. Stress levels within the shock wave far exceed the strength of solid materials; consequently, both the impactor and the target close to the impact site are irreversibly damaged. Many crystalline minerals can be transformed into higher-density phases by shock waves; for example, the common mineral quartz can be transformed into the higher-pressure forms coesite and stishovite. Many other shock-related changes take place within both impactor and target as the shock wave passes through, and some of these changes can be used as diagnostic tools to determine whether particular geological features were produced by impact cratering.",
"title": "Crater formation"
},
{
"paragraph_id": 16,
"text": "As the shock wave decays, the shocked region decompresses towards more usual pressures and densities. The damage produced by the shock wave raises the temperature of the material. In all but the smallest impacts this increase in temperature is sufficient to melt the impactor, and in larger impacts to vaporize most of it and to melt large volumes of the target. As well as being heated, the target near the impact is accelerated by the shock wave, and it continues moving away from the impact behind the decaying shock wave.",
"title": "Crater formation"
},
{
"paragraph_id": 17,
"text": "Contact, compression, decompression, and the passage of the shock wave all occur within a few tenths of a second for a large impact. The subsequent excavation of the crater occurs more slowly, and during this stage the flow of material is largely subsonic. During excavation, the crater grows as the accelerated target material moves away from the point of impact. The target's motion is initially downwards and outwards, but it becomes outwards and upwards. The flow initially produces an approximately hemispherical cavity that continues to grow, eventually producing a paraboloid (bowl-shaped) crater in which the centre has been pushed down, a significant volume of material has been ejected, and a topographically elevated crater rim has been pushed up. When this cavity has reached its maximum size, it is called the transient cavity.",
"title": "Crater formation"
},
{
"paragraph_id": 18,
"text": "The depth of the transient cavity is typically a quarter to a third of its diameter. Ejecta thrown out of the crater do not include material excavated from the full depth of the transient cavity; typically the depth of maximum excavation is only about a third of the total depth. As a result, about one third of the volume of the transient crater is formed by the ejection of material, and the remaining two thirds is formed by the displacement of material downwards, outwards and upwards, to form the elevated rim. For impacts into highly porous materials, a significant crater volume may also be formed by the permanent compaction of the pore space. Such compaction craters may be important on many asteroids, comets and small moons.",
"title": "Crater formation"
},
{
"paragraph_id": 19,
"text": "In large impacts, as well as material displaced and ejected to form the crater, significant volumes of target material may be melted and vaporized together with the original impactor. Some of this impact melt rock may be ejected, but most of it remains within the transient crater, initially forming a layer of impact melt coating the interior of the transient cavity. In contrast, the hot dense vaporized material expands rapidly out of the growing cavity, carrying some solid and molten material within it as it does so. As this hot vapor cloud expands, it rises and cools much like the archetypal mushroom cloud generated by large nuclear explosions. In large impacts, the expanding vapor cloud may rise to many times the scale height of the atmosphere, effectively expanding into free space.",
"title": "Crater formation"
},
{
"paragraph_id": 20,
"text": "Most material ejected from the crater is deposited within a few crater radii, but a small fraction may travel large distances at high velocity, and in large impacts it may exceed escape velocity and leave the impacted planet or moon entirely. The majority of the fastest material is ejected from close to the center of impact, and the slowest material is ejected close to the rim at low velocities to form an overturned coherent flap of ejecta immediately outside the rim. As ejecta escapes from the growing crater, it forms an expanding curtain in the shape of an inverted cone. The trajectory of individual particles within the curtain is thought to be largely ballistic.",
"title": "Crater formation"
},
{
"paragraph_id": 21,
"text": "Small volumes of un-melted and relatively un-shocked material may be spalled at very high relative velocities from the surface of the target and from the rear of the impactor. Spalling provides a potential mechanism whereby material may be ejected into inter-planetary space largely undamaged, and whereby small volumes of the impactor may be preserved undamaged even in large impacts. Small volumes of high-speed material may also be generated early in the impact by jetting. This occurs when two surfaces converge rapidly and obliquely at a small angle, and high-temperature highly shocked material is expelled from the convergence zone with velocities that may be several times larger than the impact velocity.",
"title": "Crater formation"
},
{
"paragraph_id": 22,
"text": "In most circumstances, the transient cavity is not stable and collapses under gravity. In small craters, less than about 4 km diameter on Earth, there is some limited collapse of the crater rim coupled with debris sliding down the crater walls and drainage of impact melts into the deeper cavity. The resultant structure is called a simple crater, and it remains bowl-shaped and superficially similar to the transient crater. In simple craters, the original excavation cavity is overlain by a lens of collapse breccia, ejecta and melt rock, and a portion of the central crater floor may sometimes be flat.",
"title": "Crater formation"
},
{
"paragraph_id": 23,
"text": "Above a certain threshold size, which varies with planetary gravity, the collapse and modification of the transient cavity is much more extensive, and the resulting structure is called a complex crater. The collapse of the transient cavity is driven by gravity, and involves both the uplift of the central region and the inward collapse of the rim. The central uplift is not the result of elastic rebound, which is a process in which a material with elastic strength attempts to return to its original geometry; rather the collapse is a process in which a material with little or no strength attempts to return to a state of gravitational equilibrium.",
"title": "Crater formation"
},
{
"paragraph_id": 24,
"text": "Complex craters have uplifted centers, and they have typically broad flat shallow crater floors, and terraced walls. At the largest sizes, one or more exterior or interior rings may appear, and the structure may be labeled an impact basin rather than an impact crater. Complex-crater morphology on rocky planets appears to follow a regular sequence with increasing size: small complex craters with a central topographic peak are called central peak craters, for example Tycho; intermediate-sized craters, in which the central peak is replaced by a ring of peaks, are called peak-ring craters, for example Schrödinger; and the largest craters contain multiple concentric topographic rings, and are called multi-ringed basins, for example Orientale. On icy (as opposed to rocky) bodies, other morphological forms appear that may have central pits rather than central peaks, and at the largest sizes may contain many concentric rings. Valhalla on Callisto is an example of this type.",
"title": "Crater formation"
},
{
"paragraph_id": 25,
"text": "Non-explosive volcanic craters can usually be distinguished from impact craters by their irregular shape and the association of volcanic flows and other volcanic materials. Impact craters produce melted rocks as well, but usually in smaller volumes with different characteristics.",
"title": "Identifying impact craters"
},
{
"paragraph_id": 26,
"text": "The distinctive mark of an impact crater is the presence of rock that has undergone shock-metamorphic effects, such as shatter cones, melted rocks, and crystal deformations. The problem is that these materials tend to be deeply buried, at least for simple craters. They tend to be revealed in the uplifted center of a complex crater, however.",
"title": "Identifying impact craters"
},
{
"paragraph_id": 27,
"text": "Impacts produce distinctive shock-metamorphic effects that allow impact sites to be distinctively identified. Such shock-metamorphic effects can include:",
"title": "Identifying impact craters"
},
{
"paragraph_id": 28,
"text": "On Earth impact craters have resulted in useful minerals. Some of the ores produced from impact related effects on Earth include ores of iron, uranium, gold, copper, and nickel. It is estimated that the value of materials mined from impact structures is five billion dollars/year just for North America. The eventual usefulness of impact craters depends on several factors especially the nature of the materials that were impacted and when the materials were affected. In some cases the deposits were already in place and the impact brought them to the surface. These are called \"progenetic economic deposits.\" Others were created during the actual impact. The great energy involved caused melting. Useful minerals formed as a result of this energy are classified as \"syngenetic deposits.\" The third type, called \"epigenetic deposits,\" is caused by the creation of a basin from the impact. Many of the minerals that our modern lives depend on are associated with impacts in the past. The Vredeford Dome in the center of the Witwatersrand Basin is the largest goldfield in the world which has supplied about 40% of all the gold ever mined in an impact structure (though the gold did not come from the bolide). The asteroid that struck the region was 9.7 km (6 mi) wide. The Sudbury Basin was caused by an impacting body over 9.7 km (6 mi) in diameter. This basin is famous for its deposits of nickel, copper, and platinum group elements. An impact was involved in making the Carswell structure in Saskatchewan, Canada; it contains uranium deposits. Hydrocarbons are common around impact structures. Fifty percent of impact structures in North America in hydrocarbon-bearing sedimentary basins contain oil/gas fields.",
"title": "Economic importance of impacts"
},
{
"paragraph_id": 29,
"text": "Because of the many missions studying Mars since the 1960s, there is good coverage of its surface which contains large numbers of craters. Many of the craters on Mars differ from those on the Moon and other moons since Mars contains ice under the ground, especially in the higher latitudes. Some of the types of craters that have special shapes due to impact into ice-rich ground are pedestal craters, rampart craters, expanded craters, and LARLE craters.",
"title": "Martian craters"
},
{
"paragraph_id": 30,
"text": "On Earth, the recognition of impact craters is a branch of geology, and is related to planetary geology in the study of other worlds. Out of many proposed craters, relatively few are confirmed. The following twenty are a sample of articles of confirmed and well-documented impact sites.",
"title": "Lists of craters"
},
{
"paragraph_id": 31,
"text": "See the Earth Impact Database, a website concerned with 190 (as of July 2019) scientifically-confirmed impact craters on Earth.",
"title": "Lists of craters"
},
{
"paragraph_id": 32,
"text": "There are approximately twelve more impact craters/basins larger than 300 km on the Moon, five on Mercury, and four on Mars. Large basins, some unnamed but mostly smaller than 300 km, can also be found on Saturn's moons Dione, Rhea and Iapetus.",
"title": "Lists of craters"
}
] | An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Lunar impact craters range from microscopic craters on lunar rocks returned by the Apollo program and small, simple, bowl-shaped depressions in the lunar regolith to large, complex, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth. Impact craters are the dominant geographic features on many solid Solar System objects including the Moon, Mercury, Callisto, Ganymede and most small moons and asteroids. On other planets and moons that experience more active surface geological processes, such as Earth, Venus, Europa, Io and Titan, visible impact craters are less common because they become eroded, buried or transformed by tectonics over time. Where such processes have destroyed most of the original crater topography, the terms impact structure or astrobleme are more commonly used. In early literature, before the significance of impact cratering was widely recognised, the terms cryptoexplosion or cryptovolcanic structure were often used to describe what are now recognised as impact-related features on Earth. The cratering records of very old surfaces, such as Mercury, the Moon, and the southern highlands of Mars, record a period of intense early bombardment in the inner Solar System around 3.9 billion years ago. The rate of crater production on Earth has since been considerably lower, but it is appreciable nonetheless. Earth experiences, on average, from one to three impacts large enough to produce a 20-kilometre-diameter (12 mi) crater every million years. This indicates that there should be far more relatively young craters on the planet than have been discovered so far. The cratering rate in the inner solar system fluctuates as a consequence of collisions in the asteroid belt that create a family of fragments that are often sent cascading into the inner solar system. Formed in a collision 80 million years ago, the Baptistina family of asteroids is thought to have caused a large spike in the impact rate. The rate of impact cratering in the outer Solar System could be different from the inner Solar System. Although Earth's active surface processes quickly destroy the impact record, about 190 terrestrial impact craters have been identified. These range in diameter from a few tens of meters up to about 300 km (190 mi), and they range in age from recent times to more than two billion years, though most are less than 500 million years old because geological processes tend to obliterate older craters. They are also selectively found in the stable interior regions of continents. Few undersea craters have been discovered because of the difficulty of surveying the sea floor, the rapid rate of change of the ocean bottom, and the subduction of the ocean floor into Earth's interior by processes of plate tectonics. Impact craters are not to be confused with landforms that may appear similar, including calderas, sinkholes, glacial cirques, ring dikes, salt domes, and others. | 2001-09-22T14:39:33Z | 2023-11-08T20:47:36Z | [
"Template:Multiple image",
"Template:Annotated link",
"Template:Cite web",
"Template:Impact cratering on Earth",
"Template:Redirect",
"Template:Convert",
"Template:Cvt",
"Template:Rp",
"Template:Sfn",
"Template:Columns-list",
"Template:Earth Impact Database world map.svg",
"Template:Cite conference",
"Template:Use British English",
"Template:As of",
"Template:Div col",
"Template:Cite journal",
"Template:Commons category-inline",
"Template:Portal bar",
"Template:Authority control",
"Template:Short description",
"Template:Main",
"Template:End div col",
"Template:Reflist",
"Template:Cite book",
"Template:Use dmy dates"
] | https://en.wikipedia.org/wiki/Impact_crater |
6,417 | Corvus (disambiguation) | Corvus is a genus of birds commonly known as crows and ravens.
Corvus may also refer to: | [
{
"paragraph_id": 0,
"text": "Corvus is a genus of birds commonly known as crows and ravens.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Corvus may also refer to:",
"title": ""
}
] | Corvus is a genus of birds commonly known as crows and ravens. Corvus may also refer to: | 2023-04-09T22:33:30Z | [
"Template:Wiktionary",
"Template:Toc right",
"Template:Intitle",
"Template:Disambiguation"
] | https://en.wikipedia.org/wiki/Corvus_(disambiguation) |
|
6,420 | Corona Borealis | Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest stars form a semicircular arc. Its Latin name, inspired by its shape, means "northern crown". In classical mythology Corona Borealis generally represented the crown given by the god Dionysus to the Cretan princess Ariadne and set by her in the heavens. Other cultures likened the pattern to a circle of elders, an eagle's nest, a bear's den or a smokehole. Ptolemy also listed a southern counterpart, Corona Australis, with a similar pattern.
The brightest star is the magnitude 2.2 Alpha Coronae Borealis. The yellow supergiant R Coronae Borealis is the prototype of a rare class of giant stars—the R Coronae Borealis variables—that are extremely hydrogen deficient, and thought to result from the merger of two white dwarfs. T Coronae Borealis, also known as the Blaze Star, is another unusual type of variable star known as a recurrent nova. Normally of magnitude 10, it last flared up to magnitude 2 in 1946. ADS 9731 and Sigma Coronae Borealis are multiple star systems with six and five components respectively. Five star systems have been found to have Jupiter-sized exoplanets. Abell 2065 is a highly concentrated galaxy cluster one billion light-years from the Solar System containing more than 400 members, and is itself part of the larger Corona Borealis Supercluster.
Covering 179 square degrees and hence 0.433% of the sky, Corona Borealis ranks 73rd of the 88 modern constellations by area. Its position in the Northern Celestial Hemisphere means that the whole constellation is visible to observers north of 50°S. It is bordered by Boötes to the north and west, Serpens Caput to the south, and Hercules to the east. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "CrB". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of eight segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between 15 16.0 and 16 25.1 , while the declination coordinates are between 39.71° and 25.54°. It has a counterpart—Corona Australis—in the Southern Celestial Hemisphere.
The seven stars that make up the constellation's distinctive crown-shaped pattern are all 4th-magnitude stars except for the brightest of them, Alpha Coronae Borealis. The other six stars are Theta, Beta, Gamma, Delta, Epsilon and Iota Coronae Borealis. The German cartographer Johann Bayer gave twenty stars in Corona Borealis Bayer designations from Alpha to Upsilon in his 1603 star atlas Uranometria. Zeta Coronae Borealis was noted to be a double star by later astronomers and its components designated Zeta and Zeta. John Flamsteed did likewise with Nu Coronae Borealis; classed by Bayer as a single star, it was noted to be two close stars by Flamsteed. He named them 20 and 21 Coronae Borealis in his catalogue, alongside the designations Nu and Nu respectively. Chinese astronomers deemed nine stars to make up the asterism, adding Pi and Rho Coronae Borealis. Within the constellation's borders, there are 37 stars brighter than or equal to apparent magnitude 6.5.
Alpha Coronae Borealis (officially named Alphecca by the IAU, but sometimes also known as Gemma) appears as a blue-white star of magnitude 2.2. In fact, it is an Algol-type eclipsing binary that varies by 0.1 magnitude with a period of 17.4 days. The primary is a white main-sequence star of spectral type A0V that is 2.91 times the mass of the Sun (M☉) and 57 times as luminous (L☉), and is surrounded by a debris disk out to a radius of around 60 astronomical units (AU). The secondary companion is a yellow main-sequence star of spectral type G5V that is a little smaller (0.9 times) the diameter of the Sun. Lying 75±0.5 light-years from Earth, Alphecca is believed to be a member of the Ursa Major Moving Group of stars that have a common motion through space.
Located 112±3 light-years away, Beta Coronae Borealis or Nusakan is a spectroscopic binary system whose two components are separated by 10 AU and orbit each other every 10.5 years. The brighter component is a rapidly oscillating Ap star, pulsating with a period of 16.2 minutes. Of spectral type A5V with a surface temperature of around 7980 K, it has around 2.1 M☉, 2.6 solar radii (R☉), and 25.3 L☉. The smaller star is of spectral type F2V with a surface temperature of around 6750 K, and has around 1.4 M☉, 1.56 R☉, and between 4 and 5 L☉. Near Nusakan is Theta Coronae Borealis, a binary system that shines with a combined magnitude of 4.13 located 380±20 light-years distant. The brighter component, Theta Coronae Borealis A, is a blue-white star that spins extremely rapidly—at a rate of around 393 km per second. A Be star, it is surrounded by a debris disk.
Flanking Alpha to the east is Gamma Coronae Borealis, yet another binary star system, whose components orbit each other every 92.94 years and are roughly as far apart from each other as the Sun and Neptune. The brighter component has been classed as a Delta Scuti variable star, though this view is not universal. The components are main sequence stars of spectral types B9V and A3V. Located 170±2 light-years away, 4.06-magnitude Delta Coronae Borealis is a yellow giant star of spectral type G3.5III that is around 2.4 M☉ and has swollen to 7.4 R☉. It has a surface temperature of 5180 K. For most of its existence, Delta Coronae Borealis was a blue-white main-sequence star of spectral type B before it ran out of hydrogen fuel in its core. Its luminosity and spectrum suggest it has just crossed the Hertzsprung gap, having finished burning core hydrogen and just begun burning hydrogen in a shell that surrounds the core.
Zeta Coronae Borealis is a double star with two blue-white components 6.3 arcseconds apart that can be readily separated at 100x magnification. The primary is of magnitude 5.1 and the secondary is of magnitude 6.0. Nu Coronae Borealis is an optical double, whose components are a similar distance from Earth but have different radial velocities, hence are assumed to be unrelated. The primary, Nu Coronae Borealis, is a red giant of spectral type M2III and magnitude 5.2, lying 640±30 light-years distant, and the secondary, Nu Coronae Borealis, is an orange-hued giant star of spectral type K5III and magnitude 5.4, estimated to be 590±30 light-years away. Sigma Coronae Borealis, on the other hand, is a true multiple star system divisible by small amateur telescopes. It is actually a complex system composed of two stars around as massive as the Sun that orbit each other every 1.14 days, orbited by a third Sun-like star every 726 years. The fourth and fifth components are a binary red dwarf system that is 14,000 AU distant from the other three stars. ADS 9731 is an even rarer multiple system in the constellation, composed of six stars, two of which are spectroscopic binaries.
Corona Borealis is home to two remarkable variable stars. T Coronae Borealis is a cataclysmic variable star also known as the Blaze Star. Normally placid around magnitude 10—it has a minimum of 10.2 and maximum of 9.9—it brightens to magnitude 2 in a period of hours, caused by a nuclear chain reaction and the subsequent explosion. T Coronae Borealis is one of a handful of stars called recurrent novae, which include T Pyxidis and U Scorpii. An outburst of T Coronae Borealis was first recorded in 1866; its second recorded outburst was in February 1946. T Coronae Borealis is a binary star with a red-hued giant primary and a white dwarf secondary, the two stars orbiting each other over a period of approximately 8 months. R Coronae Borealis is a yellow-hued variable supergiant star, over 7000 light-years from Earth, and prototype of a class of stars known as R Coronae Borealis variables. Normally of magnitude 6, its brightness periodically drops as low as magnitude 15 and then slowly increases over the next several months. These declines in magnitude come about as dust that has been ejected from the star obscures it. Direct imaging with the Hubble Space Telescope shows extensive dust clouds out to a radius of around 2000 AU from the star, corresponding with a stream of fine dust (composed of grains 5 nm in diameter) associated with the star's stellar wind and coarser dust (composed of grains with a diameter of around 0.14 µm) ejected periodically.
There are several other variables of reasonable brightness for amateur astronomer to observe, including three Mira-type long period variables: S Coronae Borealis ranges between magnitudes 5.8 and 14.1 over a period of 360 days. Located around 1946 light-years distant, it shines with a luminosity 16,643 times that of the Sun and has a surface temperature of 3033 K. One of the reddest stars in the sky, V Coronae Borealis is a cool star with a surface temperature of 2877 K that shines with a luminosity 102,831 times that of the Sun and is a remote 8810 light-years distant from Earth. Varying between magnitudes 6.9 and 12.6 over a period of 357 days, it is located near the junction of the border of Corona Borealis with Hercules and Bootes. Located 1.5° northeast of Tau Coronae Borealis, W Coronae Borealis ranges between magnitudes 7.8 and 14.3 over a period of 238 days. Another red giant, RR Coronae Borealis is a M3-type semiregular variable star that varies between magnitudes 7.3 and 8.2 over 60.8 days. RS Coronae Borealis is yet another semiregular variable red giant, which ranges between magnitudes 8.7 to 11.6 over 332 days. It is unusual in that it is a red star with a high proper motion (greater than 50 milliarcseconds a year). Meanwhile, U Coronae Borealis is an Algol-type eclipsing binary star system whose magnitude varies between 7.66 and 8.79 over a period of 3.45 days
TY Coronae Borealis is a pulsating white dwarf (of ZZ Ceti) type, which is around 70% as massive as the Sun, yet has only 1.1% of its diameter. Discovered in 1990, UW Coronae Borealis is a low-mass X-ray binary system composed of a star less massive than the Sun and a neutron star surrounded by an accretion disk that draws material from the companion star. It varies in brightness in an unusually complex manner: the two stars orbit each other every 111 minutes, yet there is another cycle of 112.6 minutes, which corresponds to the orbit of the disk around the degenerate star. The beat period of 5.5 days indicates the time the accretion disk—which is asymmetrical—takes to precess around the star.
Extrasolar planets have been confirmed in five star systems, four of which were found by the radial velocity method. The spectrum of Epsilon Coronae Borealis was analysed for seven years from 2005 to 2012, revealing a planet around 6.7 times as massive as Jupiter (MJ) orbiting every 418 days at an average distance of around 1.3 AU. Epsilon itself is a 1.7 M☉ orange giant of spectral type K2III that has swollen to 21 R☉ and 151 L☉. Kappa Coronae Borealis is a spectral type K1IV orange subgiant nearly twice as massive as the Sun; around it lies a dust debris disk, and one planet with a period of 3.4 years. This planet's mass is estimated at 2.5 MJ. The dimensions of the debris disk indicate it is likely there is a second substellar companion. Omicron Coronae Borealis is a K-type clump giant with one confirmed planet with a mass of 0.83 MJ that orbits every 187 days—one of the two least massive planets known around clump giants. HD 145457 is an orange giant of spectral type K0III found to have one planet of 2.9 MJ. Discovered by the Doppler method in 2010, it takes 176 days to complete an orbit. XO-1 is a magnitude 11 yellow main-sequence star located approximately 560 light-years away, of spectral type G1V with a mass and radius similar to the Sun. In 2006 the hot Jupiter exoplanet XO-1b was discovered orbiting XO-1 by the transit method using the XO Telescope. Roughly the size of Jupiter, it completes an orbit around its star every three days.
The discovery of a Jupiter-sized planetary companion was announced in 1997 via analysis of the radial velocity of Rho Coronae Borealis, a yellow main sequence star and Solar analog of spectral type G0V, around 57 light-years distant from Earth. More accurate measurement of data from the Hipparcos satellite subsequently showed it instead to be a low-mass star somewhere between 100 and 200 times the mass of Jupiter. Possible stable planetary orbits in the habitable zone were calculated for the binary star Eta Coronae Borealis, which is composed of two stars—yellow main sequence stars of spectral type G1V and G3V respectively—similar in mass and spectrum to the Sun. No planet has been found, but a brown dwarf companion about 63 times as massive as Jupiter with a spectral type of L8 was discovered at a distance of 3640 AU from the pair in 2001.
Corona Borealis contains few galaxies observable with amateur telescopes. NGC 6085 and 6086 are a faint spiral and elliptical galaxy respectively close enough to each other to be seen in the same visual field through a telescope. Abell 2142 is a huge (six million light-year diameter), X-ray luminous galaxy cluster that is the result of an ongoing merger between two galaxy clusters. It has a redshift of 0.0909 (meaning it is moving away from us at 27,250 km/s) and a visual magnitude of 16.0. It is about 1.2 billion light-years away. Another galaxy cluster in the constellation, RX J1532.9+3021, is approximately 3.9 billion light-years from Earth. At the cluster's center is a large elliptical galaxy containing one of the most massive and most powerful supermassive black holes yet discovered. Abell 2065 is a highly concentrated galaxy cluster containing more than 400 members, the brightest of which are 16th magnitude; the cluster is more than one billion light-years from Earth. On a larger scale still, Abell 2065, along with Abell 2061, Abell 2067, Abell 2079, Abell 2089, and Abell 2092, make up the Corona Borealis Supercluster. Another galaxy cluster, Abell 2162, is a member of the Hercules Superclusters.
In Greek mythology, Corona Borealis was linked to the legend of Theseus and the minotaur. It was generally considered to represent a crown given by Dionysus to Ariadne, the daughter of Minos of Crete, after she had been abandoned by the Athenian prince Theseus. When she wore the crown at her marriage to Dionysus, he placed it in the heavens to commemorate their wedding. An alternative version has the besotted Dionysus give the crown to Ariadne, who in turn gives it to Theseus after he arrives in Crete to kill the minotaur that the Cretans have demanded tribute from Athens to feed. The hero uses the crown's light to escape the labyrinth after disposing of the creature, and Dionysus later sets it in the heavens. The Latin author Hyginus linked it to a crown or wreath worn by Bacchus (Dionysus) to disguise his appearance when first approaching Mount Olympus and revealing himself to the gods, having been previously hidden as yet another child of Jupiter's trysts with a mortal, in this case Semele. Corona Borealis was one of the 48 constellations mentioned in the Almagest of classical astronomer Ptolemy.
In Mesopotamia, Corona Borealis was associated with the goddess Nanaya.
In Welsh mythology, it was called Caer Arianrhod, "the Castle of the Silver Circle", and was the heavenly abode of the Lady Arianrhod. To the ancient Balts, Corona Borealis was known as Darželis, the "flower garden."
The Arabs called the constellation Alphecca (a name later given to Alpha Coronae Borealis), which means "separated" or "broken up" (الفكة al-Fakkah), a reference to the resemblance of the stars of Corona Borealis to a loose string of jewels. This was also interpreted as a broken dish. Among the Bedouins, the constellation was known as qaṣʿat al-masākīn (قصعة المساكين), or "the dish/bowl of the poor people".
The Skidi people of Native Americans saw the stars of Corona Borealis representing a council of stars whose chief was Polaris. The constellation also symbolised the smokehole over a fireplace, which conveyed their messages to the gods, as well as how chiefs should come together to consider matters of importance. The Shawnee people saw the stars as the Heavenly Sisters, who descended from the sky every night to dance on earth. Alphecca signifies the youngest and most comely sister, who was seized by a hunter who transformed into a field mouse to get close to her. They married though she later returned to the sky, with her heartbroken husband and son following later. The Mi'kmaq of eastern Canada saw Corona Borealis as Mskegwǒm, the den of the celestial bear (Alpha, Beta, Gamma and Delta Ursae Majoris).
Polynesian peoples often recognized Corona Borealis; the people of the Tuamotus named it Na Kaua-ki-tokerau and probably Te Hetu. The constellation was likely called Kaua-mea in Hawaii, Rangawhenua in New Zealand, and Te Wale-o-Awitu in the Cook Islands atoll of Pukapuka. Its name in Tonga was uncertain; it was either called Ao-o-Uvea or Kau-kupenga.
In Australian Aboriginal astronomy, the constellation is called womera ("the boomerang") due to the shape of the stars. The Wailwun people of northwestern New South Wales saw Corona Borealis as mullion wollai "eagle's nest", with Altair and Vega—each called mullion—the pair of eagles accompanying it. The Wardaman people of northern Australia held the constellation to be a gathering point for Men's Law, Women's Law and Law of both sexes come together and consider matters of existence.
Corona Borealis was renamed Corona Firmiana in honour of the Archbishop of Salzburg in the 1730 Atlas Mercurii Philosophicii Firmamentum Firminianum Descriptionem by Corbinianus Thomas, but this was not taken up by subsequent cartographers. The constellation was featured as a main plot ingredient in the short story "Hypnos" by H. P. Lovecraft, published in 1923; it is the object of fear of one of the protagonists in the short story. Finnish band Cadacross released an album titled Corona Borealis in 2002. | [
{
"paragraph_id": 0,
"text": "Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest stars form a semicircular arc. Its Latin name, inspired by its shape, means \"northern crown\". In classical mythology Corona Borealis generally represented the crown given by the god Dionysus to the Cretan princess Ariadne and set by her in the heavens. Other cultures likened the pattern to a circle of elders, an eagle's nest, a bear's den or a smokehole. Ptolemy also listed a southern counterpart, Corona Australis, with a similar pattern.",
"title": ""
},
{
"paragraph_id": 1,
"text": "The brightest star is the magnitude 2.2 Alpha Coronae Borealis. The yellow supergiant R Coronae Borealis is the prototype of a rare class of giant stars—the R Coronae Borealis variables—that are extremely hydrogen deficient, and thought to result from the merger of two white dwarfs. T Coronae Borealis, also known as the Blaze Star, is another unusual type of variable star known as a recurrent nova. Normally of magnitude 10, it last flared up to magnitude 2 in 1946. ADS 9731 and Sigma Coronae Borealis are multiple star systems with six and five components respectively. Five star systems have been found to have Jupiter-sized exoplanets. Abell 2065 is a highly concentrated galaxy cluster one billion light-years from the Solar System containing more than 400 members, and is itself part of the larger Corona Borealis Supercluster.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Covering 179 square degrees and hence 0.433% of the sky, Corona Borealis ranks 73rd of the 88 modern constellations by area. Its position in the Northern Celestial Hemisphere means that the whole constellation is visible to observers north of 50°S. It is bordered by Boötes to the north and west, Serpens Caput to the south, and Hercules to the east. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is \"CrB\". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of eight segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between 15 16.0 and 16 25.1 , while the declination coordinates are between 39.71° and 25.54°. It has a counterpart—Corona Australis—in the Southern Celestial Hemisphere.",
"title": "Characteristics"
},
{
"paragraph_id": 3,
"text": "The seven stars that make up the constellation's distinctive crown-shaped pattern are all 4th-magnitude stars except for the brightest of them, Alpha Coronae Borealis. The other six stars are Theta, Beta, Gamma, Delta, Epsilon and Iota Coronae Borealis. The German cartographer Johann Bayer gave twenty stars in Corona Borealis Bayer designations from Alpha to Upsilon in his 1603 star atlas Uranometria. Zeta Coronae Borealis was noted to be a double star by later astronomers and its components designated Zeta and Zeta. John Flamsteed did likewise with Nu Coronae Borealis; classed by Bayer as a single star, it was noted to be two close stars by Flamsteed. He named them 20 and 21 Coronae Borealis in his catalogue, alongside the designations Nu and Nu respectively. Chinese astronomers deemed nine stars to make up the asterism, adding Pi and Rho Coronae Borealis. Within the constellation's borders, there are 37 stars brighter than or equal to apparent magnitude 6.5.",
"title": "Features"
},
{
"paragraph_id": 4,
"text": "Alpha Coronae Borealis (officially named Alphecca by the IAU, but sometimes also known as Gemma) appears as a blue-white star of magnitude 2.2. In fact, it is an Algol-type eclipsing binary that varies by 0.1 magnitude with a period of 17.4 days. The primary is a white main-sequence star of spectral type A0V that is 2.91 times the mass of the Sun (M☉) and 57 times as luminous (L☉), and is surrounded by a debris disk out to a radius of around 60 astronomical units (AU). The secondary companion is a yellow main-sequence star of spectral type G5V that is a little smaller (0.9 times) the diameter of the Sun. Lying 75±0.5 light-years from Earth, Alphecca is believed to be a member of the Ursa Major Moving Group of stars that have a common motion through space.",
"title": "Features"
},
{
"paragraph_id": 5,
"text": "Located 112±3 light-years away, Beta Coronae Borealis or Nusakan is a spectroscopic binary system whose two components are separated by 10 AU and orbit each other every 10.5 years. The brighter component is a rapidly oscillating Ap star, pulsating with a period of 16.2 minutes. Of spectral type A5V with a surface temperature of around 7980 K, it has around 2.1 M☉, 2.6 solar radii (R☉), and 25.3 L☉. The smaller star is of spectral type F2V with a surface temperature of around 6750 K, and has around 1.4 M☉, 1.56 R☉, and between 4 and 5 L☉. Near Nusakan is Theta Coronae Borealis, a binary system that shines with a combined magnitude of 4.13 located 380±20 light-years distant. The brighter component, Theta Coronae Borealis A, is a blue-white star that spins extremely rapidly—at a rate of around 393 km per second. A Be star, it is surrounded by a debris disk.",
"title": "Features"
},
{
"paragraph_id": 6,
"text": "Flanking Alpha to the east is Gamma Coronae Borealis, yet another binary star system, whose components orbit each other every 92.94 years and are roughly as far apart from each other as the Sun and Neptune. The brighter component has been classed as a Delta Scuti variable star, though this view is not universal. The components are main sequence stars of spectral types B9V and A3V. Located 170±2 light-years away, 4.06-magnitude Delta Coronae Borealis is a yellow giant star of spectral type G3.5III that is around 2.4 M☉ and has swollen to 7.4 R☉. It has a surface temperature of 5180 K. For most of its existence, Delta Coronae Borealis was a blue-white main-sequence star of spectral type B before it ran out of hydrogen fuel in its core. Its luminosity and spectrum suggest it has just crossed the Hertzsprung gap, having finished burning core hydrogen and just begun burning hydrogen in a shell that surrounds the core.",
"title": "Features"
},
{
"paragraph_id": 7,
"text": "Zeta Coronae Borealis is a double star with two blue-white components 6.3 arcseconds apart that can be readily separated at 100x magnification. The primary is of magnitude 5.1 and the secondary is of magnitude 6.0. Nu Coronae Borealis is an optical double, whose components are a similar distance from Earth but have different radial velocities, hence are assumed to be unrelated. The primary, Nu Coronae Borealis, is a red giant of spectral type M2III and magnitude 5.2, lying 640±30 light-years distant, and the secondary, Nu Coronae Borealis, is an orange-hued giant star of spectral type K5III and magnitude 5.4, estimated to be 590±30 light-years away. Sigma Coronae Borealis, on the other hand, is a true multiple star system divisible by small amateur telescopes. It is actually a complex system composed of two stars around as massive as the Sun that orbit each other every 1.14 days, orbited by a third Sun-like star every 726 years. The fourth and fifth components are a binary red dwarf system that is 14,000 AU distant from the other three stars. ADS 9731 is an even rarer multiple system in the constellation, composed of six stars, two of which are spectroscopic binaries.",
"title": "Features"
},
{
"paragraph_id": 8,
"text": "Corona Borealis is home to two remarkable variable stars. T Coronae Borealis is a cataclysmic variable star also known as the Blaze Star. Normally placid around magnitude 10—it has a minimum of 10.2 and maximum of 9.9—it brightens to magnitude 2 in a period of hours, caused by a nuclear chain reaction and the subsequent explosion. T Coronae Borealis is one of a handful of stars called recurrent novae, which include T Pyxidis and U Scorpii. An outburst of T Coronae Borealis was first recorded in 1866; its second recorded outburst was in February 1946. T Coronae Borealis is a binary star with a red-hued giant primary and a white dwarf secondary, the two stars orbiting each other over a period of approximately 8 months. R Coronae Borealis is a yellow-hued variable supergiant star, over 7000 light-years from Earth, and prototype of a class of stars known as R Coronae Borealis variables. Normally of magnitude 6, its brightness periodically drops as low as magnitude 15 and then slowly increases over the next several months. These declines in magnitude come about as dust that has been ejected from the star obscures it. Direct imaging with the Hubble Space Telescope shows extensive dust clouds out to a radius of around 2000 AU from the star, corresponding with a stream of fine dust (composed of grains 5 nm in diameter) associated with the star's stellar wind and coarser dust (composed of grains with a diameter of around 0.14 µm) ejected periodically.",
"title": "Features"
},
{
"paragraph_id": 9,
"text": "There are several other variables of reasonable brightness for amateur astronomer to observe, including three Mira-type long period variables: S Coronae Borealis ranges between magnitudes 5.8 and 14.1 over a period of 360 days. Located around 1946 light-years distant, it shines with a luminosity 16,643 times that of the Sun and has a surface temperature of 3033 K. One of the reddest stars in the sky, V Coronae Borealis is a cool star with a surface temperature of 2877 K that shines with a luminosity 102,831 times that of the Sun and is a remote 8810 light-years distant from Earth. Varying between magnitudes 6.9 and 12.6 over a period of 357 days, it is located near the junction of the border of Corona Borealis with Hercules and Bootes. Located 1.5° northeast of Tau Coronae Borealis, W Coronae Borealis ranges between magnitudes 7.8 and 14.3 over a period of 238 days. Another red giant, RR Coronae Borealis is a M3-type semiregular variable star that varies between magnitudes 7.3 and 8.2 over 60.8 days. RS Coronae Borealis is yet another semiregular variable red giant, which ranges between magnitudes 8.7 to 11.6 over 332 days. It is unusual in that it is a red star with a high proper motion (greater than 50 milliarcseconds a year). Meanwhile, U Coronae Borealis is an Algol-type eclipsing binary star system whose magnitude varies between 7.66 and 8.79 over a period of 3.45 days",
"title": "Features"
},
{
"paragraph_id": 10,
"text": "TY Coronae Borealis is a pulsating white dwarf (of ZZ Ceti) type, which is around 70% as massive as the Sun, yet has only 1.1% of its diameter. Discovered in 1990, UW Coronae Borealis is a low-mass X-ray binary system composed of a star less massive than the Sun and a neutron star surrounded by an accretion disk that draws material from the companion star. It varies in brightness in an unusually complex manner: the two stars orbit each other every 111 minutes, yet there is another cycle of 112.6 minutes, which corresponds to the orbit of the disk around the degenerate star. The beat period of 5.5 days indicates the time the accretion disk—which is asymmetrical—takes to precess around the star.",
"title": "Features"
},
{
"paragraph_id": 11,
"text": "Extrasolar planets have been confirmed in five star systems, four of which were found by the radial velocity method. The spectrum of Epsilon Coronae Borealis was analysed for seven years from 2005 to 2012, revealing a planet around 6.7 times as massive as Jupiter (MJ) orbiting every 418 days at an average distance of around 1.3 AU. Epsilon itself is a 1.7 M☉ orange giant of spectral type K2III that has swollen to 21 R☉ and 151 L☉. Kappa Coronae Borealis is a spectral type K1IV orange subgiant nearly twice as massive as the Sun; around it lies a dust debris disk, and one planet with a period of 3.4 years. This planet's mass is estimated at 2.5 MJ. The dimensions of the debris disk indicate it is likely there is a second substellar companion. Omicron Coronae Borealis is a K-type clump giant with one confirmed planet with a mass of 0.83 MJ that orbits every 187 days—one of the two least massive planets known around clump giants. HD 145457 is an orange giant of spectral type K0III found to have one planet of 2.9 MJ. Discovered by the Doppler method in 2010, it takes 176 days to complete an orbit. XO-1 is a magnitude 11 yellow main-sequence star located approximately 560 light-years away, of spectral type G1V with a mass and radius similar to the Sun. In 2006 the hot Jupiter exoplanet XO-1b was discovered orbiting XO-1 by the transit method using the XO Telescope. Roughly the size of Jupiter, it completes an orbit around its star every three days.",
"title": "Features"
},
{
"paragraph_id": 12,
"text": "The discovery of a Jupiter-sized planetary companion was announced in 1997 via analysis of the radial velocity of Rho Coronae Borealis, a yellow main sequence star and Solar analog of spectral type G0V, around 57 light-years distant from Earth. More accurate measurement of data from the Hipparcos satellite subsequently showed it instead to be a low-mass star somewhere between 100 and 200 times the mass of Jupiter. Possible stable planetary orbits in the habitable zone were calculated for the binary star Eta Coronae Borealis, which is composed of two stars—yellow main sequence stars of spectral type G1V and G3V respectively—similar in mass and spectrum to the Sun. No planet has been found, but a brown dwarf companion about 63 times as massive as Jupiter with a spectral type of L8 was discovered at a distance of 3640 AU from the pair in 2001.",
"title": "Features"
},
{
"paragraph_id": 13,
"text": "Corona Borealis contains few galaxies observable with amateur telescopes. NGC 6085 and 6086 are a faint spiral and elliptical galaxy respectively close enough to each other to be seen in the same visual field through a telescope. Abell 2142 is a huge (six million light-year diameter), X-ray luminous galaxy cluster that is the result of an ongoing merger between two galaxy clusters. It has a redshift of 0.0909 (meaning it is moving away from us at 27,250 km/s) and a visual magnitude of 16.0. It is about 1.2 billion light-years away. Another galaxy cluster in the constellation, RX J1532.9+3021, is approximately 3.9 billion light-years from Earth. At the cluster's center is a large elliptical galaxy containing one of the most massive and most powerful supermassive black holes yet discovered. Abell 2065 is a highly concentrated galaxy cluster containing more than 400 members, the brightest of which are 16th magnitude; the cluster is more than one billion light-years from Earth. On a larger scale still, Abell 2065, along with Abell 2061, Abell 2067, Abell 2079, Abell 2089, and Abell 2092, make up the Corona Borealis Supercluster. Another galaxy cluster, Abell 2162, is a member of the Hercules Superclusters.",
"title": "Features"
},
{
"paragraph_id": 14,
"text": "In Greek mythology, Corona Borealis was linked to the legend of Theseus and the minotaur. It was generally considered to represent a crown given by Dionysus to Ariadne, the daughter of Minos of Crete, after she had been abandoned by the Athenian prince Theseus. When she wore the crown at her marriage to Dionysus, he placed it in the heavens to commemorate their wedding. An alternative version has the besotted Dionysus give the crown to Ariadne, who in turn gives it to Theseus after he arrives in Crete to kill the minotaur that the Cretans have demanded tribute from Athens to feed. The hero uses the crown's light to escape the labyrinth after disposing of the creature, and Dionysus later sets it in the heavens. The Latin author Hyginus linked it to a crown or wreath worn by Bacchus (Dionysus) to disguise his appearance when first approaching Mount Olympus and revealing himself to the gods, having been previously hidden as yet another child of Jupiter's trysts with a mortal, in this case Semele. Corona Borealis was one of the 48 constellations mentioned in the Almagest of classical astronomer Ptolemy.",
"title": "Mythology"
},
{
"paragraph_id": 15,
"text": "In Mesopotamia, Corona Borealis was associated with the goddess Nanaya.",
"title": "Mythology"
},
{
"paragraph_id": 16,
"text": "In Welsh mythology, it was called Caer Arianrhod, \"the Castle of the Silver Circle\", and was the heavenly abode of the Lady Arianrhod. To the ancient Balts, Corona Borealis was known as Darželis, the \"flower garden.\"",
"title": "Mythology"
},
{
"paragraph_id": 17,
"text": "The Arabs called the constellation Alphecca (a name later given to Alpha Coronae Borealis), which means \"separated\" or \"broken up\" (الفكة al-Fakkah), a reference to the resemblance of the stars of Corona Borealis to a loose string of jewels. This was also interpreted as a broken dish. Among the Bedouins, the constellation was known as qaṣʿat al-masākīn (قصعة المساكين), or \"the dish/bowl of the poor people\".",
"title": "Mythology"
},
{
"paragraph_id": 18,
"text": "The Skidi people of Native Americans saw the stars of Corona Borealis representing a council of stars whose chief was Polaris. The constellation also symbolised the smokehole over a fireplace, which conveyed their messages to the gods, as well as how chiefs should come together to consider matters of importance. The Shawnee people saw the stars as the Heavenly Sisters, who descended from the sky every night to dance on earth. Alphecca signifies the youngest and most comely sister, who was seized by a hunter who transformed into a field mouse to get close to her. They married though she later returned to the sky, with her heartbroken husband and son following later. The Mi'kmaq of eastern Canada saw Corona Borealis as Mskegwǒm, the den of the celestial bear (Alpha, Beta, Gamma and Delta Ursae Majoris).",
"title": "Mythology"
},
{
"paragraph_id": 19,
"text": "Polynesian peoples often recognized Corona Borealis; the people of the Tuamotus named it Na Kaua-ki-tokerau and probably Te Hetu. The constellation was likely called Kaua-mea in Hawaii, Rangawhenua in New Zealand, and Te Wale-o-Awitu in the Cook Islands atoll of Pukapuka. Its name in Tonga was uncertain; it was either called Ao-o-Uvea or Kau-kupenga.",
"title": "Mythology"
},
{
"paragraph_id": 20,
"text": "In Australian Aboriginal astronomy, the constellation is called womera (\"the boomerang\") due to the shape of the stars. The Wailwun people of northwestern New South Wales saw Corona Borealis as mullion wollai \"eagle's nest\", with Altair and Vega—each called mullion—the pair of eagles accompanying it. The Wardaman people of northern Australia held the constellation to be a gathering point for Men's Law, Women's Law and Law of both sexes come together and consider matters of existence.",
"title": "Mythology"
},
{
"paragraph_id": 21,
"text": "Corona Borealis was renamed Corona Firmiana in honour of the Archbishop of Salzburg in the 1730 Atlas Mercurii Philosophicii Firmamentum Firminianum Descriptionem by Corbinianus Thomas, but this was not taken up by subsequent cartographers. The constellation was featured as a main plot ingredient in the short story \"Hypnos\" by H. P. Lovecraft, published in 1923; it is the object of fear of one of the protagonists in the short story. Finnish band Cadacross released an album titled Corona Borealis in 2002.",
"title": "Mythology"
}
] | Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest stars form a semicircular arc. Its Latin name, inspired by its shape, means "northern crown". In classical mythology Corona Borealis generally represented the crown given by the god Dionysus to the Cretan princess Ariadne and set by her in the heavens. Other cultures likened the pattern to a circle of elders, an eagle's nest, a bear's den or a smokehole. Ptolemy also listed a southern counterpart, Corona Australis, with a similar pattern. The brightest star is the magnitude 2.2 Alpha Coronae Borealis. The yellow supergiant R Coronae Borealis is the prototype of a rare class of giant stars—the R Coronae Borealis variables—that are extremely hydrogen deficient, and thought to result from the merger of two white dwarfs. T Coronae Borealis, also known as the Blaze Star, is another unusual type of variable star known as a recurrent nova. Normally of magnitude 10, it last flared up to magnitude 2 in 1946. ADS 9731 and Sigma Coronae Borealis are multiple star systems with six and five components respectively. Five star systems have been found to have Jupiter-sized exoplanets. Abell 2065 is a highly concentrated galaxy cluster one billion light-years from the Solar System containing more than 400 members, and is itself part of the larger Corona Borealis Supercluster. | 2001-09-17T18:52:04Z | 2023-12-30T16:25:24Z | [
"Template:Featured article",
"Template:Redirect",
"Template:Clear",
"Template:Transl",
"Template:Sky",
"Template:Infobox constellation",
"Template:Cite book",
"Template:Authority control",
"Template:Notelist",
"Template:Cite web",
"Template:Portal bar",
"Template:Short description",
"Template:Solar luminosity",
"Template:Convert",
"Template:Reflist",
"Template:Jupiter mass",
"Template:Circa",
"Template:Lang",
"Template:Commons-inline",
"Template:Efn",
"Template:See also",
"Template:Solar mass",
"Template:Solar radius",
"Template:Cite journal",
"Template:Stars of Corona Borealis",
"Template:Constellations",
"Template:RA",
"Template:Sfn"
] | https://en.wikipedia.org/wiki/Corona_Borealis |
6,421 | Cygnus (constellation) | Cygnus is a northern constellation on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. Cygnus is one of the most recognizable constellations of the northern summer and autumn, and it features a prominent asterism known as the Northern Cross (in contrast to the Southern Cross). Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.
Cygnus contains Deneb (ذنب, translit. ḏanab, tail) – one of the brightest stars in the night sky and the most distant first-magnitude star – as its "tail star" and one corner of the Summer Triangle the constellation forming an east pointing altitude of the triangle. It also has some notable X-ray sources and the giant stellar association of Cygnus OB2. Cygnus is also known as the Northern Cross. One of the stars of this association, NML Cygni, is one of the largest stars currently known. The constellation is also home to Cygnus X-1, a distant X-ray binary containing a supergiant and unseen massive companion that was the first object widely held to be a black hole. Many star systems in Cygnus have known planets as a result of the Kepler Mission observing one patch of the sky, an area around Cygnus.
Most of the east has part of the Hercules–Corona Borealis Great Wall in the deep sky, a giant galaxy filament that is the largest known structure in the observable universe, covering most of the northern sky.
In Hinduism, the period of time (or Muhurta) between 4:24 AM to 5:12 AM is called the Brahmamuhurtha, which means "the moment of the Universe"; the star system in correlation is the Cygnus constellation. This is believed to be a highly auspicious time to meditate, do any task, or start the day.
In Polynesia, Cygnus was often recognized as a separate constellation. In Tonga it was called Tuula-lupe, and in the Tuamotus it was called Fanui-tai. In New Zealand it was called Mara-tea, in the Society Islands it was called Pirae-tea or Taurua-i-te-haapa-raa-manu, and in the Tuamotus it was called Fanui-raro. Beta Cygni was named in New Zealand; it was likely called Whetu-kaupo. Gamma Cygni was called Fanui-runga in the Tuamotus.
Deneb was also often a given name, in the Islamic world of astronomy. The name Deneb comes from the Arabic name dhaneb, meaning "tail", from the phrase Dhanab ad-Dajājah, which means "the tail of the hen".
In Greek mythology, Cygnus has been identified with several different legendary swans. Zeus disguised himself as a swan to seduce Leda, Spartan king Tyndareus's wife, who gave birth to the Gemini, Helen of Troy, and Clytemnestra; Orpheus was transformed into a swan after his murder, and was said to have been placed in the sky next to his lyre (Lyra); and the King Cygnus was transformed into a swan.
Later Romans also associated this constellation with the tragic story of Phaethon, the son of Helios the sun god, who demanded to ride his father's sun chariot for a day. Phaethon, however, was unable to control the reins, forcing Zeus to destroy the chariot (and Phaethon) with a thunderbolt, causing it to plummet to the earth into the river Eridanus. According to the myth, Phaethon's close friend or lover, Cygnus, grieved bitterly and spent many days diving into the river to collect Phaethon's bones to give him a proper burial. The gods were so touched by Cygnus's devotion that they turned him into a swan and placed him among the stars.
In Ovid's Metamorphoses, there are three people named Cygnus, all of whom are transformed into swans. Alongside Cygnus, noted above, he mentions a boy from Tempe who commits suicide when Phyllius refuses to give him a tamed bull that he demands, but is transformed into a swan and flies away. He also mentions a son of Neptune who is an invulnerable warrior in the Trojan War who is eventually defeated by Achilles, but Neptune saves him by transforming him into a swan.
Together with other avian constellations near the summer solstice, Vultur cadens and Aquila, Cygnus may be a significant part of the origin of the myth of the Stymphalian Birds, one of The Twelve Labours of Hercules.
A very large constellation, Cygnus is bordered by Cepheus to the north and east, Draco to the north and west, Lyra to the west, Vulpecula to the south, Pegasus to the southeast and Lacerta to the east. The three-letter abbreviation for the constellation, as adopted by the IAU in 1922, is "Cyg". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined as a polygon of 28 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 19 07.3 and 22 02.3 , while the declination coordinates are between 27.73° and 61.36°. Covering 804 square degrees and around 1.9% of the night sky, Cygnus ranks 16th of the 88 constellations in size.
Cygnus culminates at midnight on 29 June, and is most visible in the evening from the early summer to mid-autumn in the Northern Hemisphere.
Normally, Cygnus is depicted with Delta and Epsilon Cygni as its wings. Deneb, the brightest in the constellation is at its tail, and Albireo as the tip of its beak.
There are several asterisms in Cygnus. In the 17th-century German celestial cartographer Johann Bayer's star atlas the Uranometria, Alpha, Beta and Gamma Cygni form the pole of a cross, while Delta and Epsilon form the cross beam. The nova P Cygni was then considered to be the body of Christ.
There is an abundance of deep-sky objects, with many open clusters, nebulae of various types and supernova remnants found in Cygnus due to its position on the Milky Way.
Its molecular clouds form the apparent Cygnus Rift dark nebula constellation, which is one end of the apparent part of the apparent Great Rift along the Milky Way's galactic plane. The rift begins with features like the Northern Coalsack which obscures the further away and large in apparent size Cygnus molecular cloud complex which the North America Nebula is part of.
Bayer catalogued many stars in the constellation, giving them the Bayer designations from Alpha to Omega and then using lowercase Roman letters to g. John Flamsteed added the Roman letters h, i, k, l and m (these stars were considered informes by Bayer as they lay outside the asterism of Cygnus), but were dropped by Francis Baily.
There are several bright stars in Cygnus. α Cygni, called Deneb, is the brightest star in Cygnus. It is a white supergiant star of spectral type A2Iae that varies between magnitudes 1.21 and 1.29, one of the largest and most luminous A-class stars known. It is located about 2600 light-years away. Its traditional name means "tail" and refers to its position in the constellation. Albireo, designated β Cygni, is a celebrated binary star among amateur astronomers for its contrasting hues. The primary is an orange-hued giant star of magnitude 3.1 and the secondary is a blue-green hued star of magnitude 5.1. The system is 430 light-years away and is visible in large binoculars and all amateur telescopes. γ Cygni, traditionally named Sadr, is a yellow-tinged supergiant star of magnitude 2.2, 1800 light-years away. Its traditional name means "breast" and refers to its position in the constellation. δ Cygni (the proper name is Fawaris) is another bright binary star in Cygnus, 166 light-years with a period of 800 years. The primary is a blue-white hued giant star of magnitude 2.9, and the secondary is a star of magnitude 6.6. The two components are visible in a medium-sized amateur telescope. The fifth star in Cygnus above magnitude 3 is Aljanah, designated ε Cygni. It is an orange-hued giant star of magnitude 2.5, 72 light-years from Earth.
There are several other dimmer double and binary stars in Cygnus. μ Cygni is a binary star with an optical tertiary component. The binary system has a period of 790 years and is 73 light-years from Earth. The primary and secondary, both white stars, are of magnitude 4.8 and 6.2, respectively. The unrelated tertiary component is of magnitude 6.9. Though the tertiary component is visible in binoculars, the primary and secondary currently require a medium-sized amateur telescope to split, as they will through the year 2020. The two stars will be closest between 2043 and 2050, when they will require a telescope with larger aperture to split. The stars 30 and 31 Cygni form a contrasting double star similar to the brighter Albireo. The two are visible in binoculars. The primary, 31 Cygni, is an orange-hued star of magnitude 3.8, 1400 light-years from Earth. The secondary, 30 Cygni, appears blue-green. It is of spectral type A5IIIn and magnitude 4.83, and is around 610 light-years from Earth. 31 Cygni itself is a binary star; the tertiary component is a blue star of magnitude 7.0. ψ Cygni is a binary star visible in small amateur telescopes, with two white components. The primary is of magnitude 5.0 and the secondary is of magnitude 7.5. 61 Cygni is a binary star visible in large binoculars or a small amateur telescope. It is 11.4 light-years from Earth and has a period of 750 years. Both components are orange-hued dwarf (main sequence) stars; the primary is of magnitude 5.2 and the secondary is of magnitude 6.1. 61 Cygni is significant because Friedrich Wilhelm Bessel determined its parallax in 1838, the first star to have a known parallax.
Located near η Cygni is the X-ray source Cygnus X-1, which is now thought to be caused by a black hole accreting matter in a binary star system. This was the first X-ray source widely believed to be a black hole. It is located approximately 2.2 kiloparsecs from the Sun. There is also supergiant variable star in the system which is known as HDE 226868.
Cygnus also contains several other noteworthy X-ray sources. Cygnus X-3 is a microquasar containing a Wolf–Rayet star in orbit around a very compact object, with a period of only 4.8 hours. The system is one of the most intrinsically luminous X-ray sources observed. The system undergoes periodic outbursts of unknown nature, and during one such outburst, the system was found to be emitting muons, likely caused by neutrinos. While the compact object is thought to be a neutron star or possibly a black hole, it is possible that the object is instead a more exotic stellar remnant, possibly the first discovered quark star, hypothesized due to its production of cosmic rays that cannot be explained if the object is a normal neutron star. The system also emits cosmic rays and gamma rays, and has helped shed insight on to the formation of such rays. Cygnus X-2 is another X-ray binary, containing an A-type giant in orbit around a neutron star with a 9.8-day period. The system is interesting due to the rather small mass of the companion star, as most millisecond pulsars have much more massive companions. Another black hole in Cygnus is V404 Cygni, which consists of a K-type star orbiting around a black hole of around 12 solar masses. The black hole, similar to that of Cygnus X-3, has been hypothesized to be a quark star. 4U 2129+ 47 is another X-ray binary containing a neutron star which undergoes outbursts, as is EXO 2030+ 375.
Cygnus is also home to several variable stars. SS Cygni is a dwarf nova which undergoes outbursts every 7–8 weeks. The system's total magnitude varies from 12th magnitude at its dimmest to 8th magnitude at its brightest. The two objects in the system are incredibly close together, with an orbital period of less than 0.28 days. χ Cygni is a red giant and the second-brightest Mira variable star at its maximum. It ranges between magnitudes 3.3 and 14.2, and spectral types S6,2e to S10,4e (MSe) over a period of 408 days; it has a diameter of 300 solar diameters and is 350 light-years from Earth. P Cygni is a luminous blue variable that brightened suddenly to 3rd magnitude in 1600 AD. Since 1715, the star has been of 5th magnitude, despite being more than 5000 light-years from Earth. The star's spectrum is unusual in that it contains very strong emission lines resulting from surrounding nebulosity. W Cygni is a semi-regular variable red giant star, 618 light-years from Earth.It has a maximum magnitude of 5.10 and a minimum magnitude 6.83; its period of 131 days. It is a red giant ranging between spectral types M4e-M6e(Tc:)III, NML Cygni is a red hypergiant semi-regular variable star located at 5,300 light-years away from Earth. It is one of largest stars currently known in the galaxy with a radius exceeding 1,000 solar radii. Its magnitude is around 16.6, its period is about 940 days.
The star KIC 8462852 (Tabby's Star) has received widespread press coverage because of unusual light fluctuations.
Cygnus is one of the constellations that the Kepler satellite surveyed in its search for exoplanets, and as a result, there are about a hundred stars in Cygnus with known planets, the most of any constellation. One of the most notable systems is the Kepler-11 system, containing six transiting planets, all within a plane of approximately one degree. It was the system with six exoplanets to be discovered. With a spectral type of G6V, the star is somewhat cooler than the Sun. The planets are very close to the star; all but the last planet are closer to Kepler-11 than Mercury is to the Sun, and all the planets are more massive than Earth, and have low densities. The planets have low densities. The naked-eye star 16 Cygni, a triple star approximately 70 light-years from Earth composed two Sun-like stars and a red dwarf, contains a planet orbiting one of the sun-like stars, found due to variations in the star's radial velocity. Gliese 777, another naked-eye multiple star system containing a yellow star and a red dwarf, also contains a planet. The planet is somewhat similar to Jupiter, but with slightly more mass and a more eccentric orbit. The Kepler-22 system is also notable for having the most Earth-like exoplanet when it was discovered in 2011.
The rich background of stars of Cygnus can make it difficult to make out open cluster.
M39 (NGC 7092) is an open cluster 950 light-years from Earth that are visible to the unaided eye under dark skies. It is loose, with about 30 stars arranged over a wide area; their conformation appears triangular. The brightest stars of M39 are of the 7th magnitude. Another open cluster in Cygnus is NGC 6910, also called the Rocking Horse Cluster, possessing 16 stars with a diameter of 5 arcminutes visible in a small amateur instrument; it is of magnitude 7.4. The brightest of these are two gold-hued stars, which represent the bottom of the toy it is named for. A larger amateur instrument reveals 8 more stars, nebulosity to the east and west of the cluster, and a diameter of 9 arcminutes. The nebulosity in this region is part of the Gamma Cygni Nebula. The other stars, approximately 3700 light-years from Earth, are mostly blue-white and very hot.
Other open clusters in Cygnus include Dolidze 9, Collinder 421, Dolidze 11, and Berkeley 90. Dolidze 9, 2800 light-years from Earth and relatively young at 20 million light-years old, is a faint open cluster with up to 22 stars visible in small and medium-sized amateur telescopes. Nebulosity is visible to the north and east of the cluster, which is 7 arcminutes in diameter. The brightest star appears in the eastern part of the cluster and is of the 7th magnitude; another bright star has a yellow hue. Dolidze 11 is an open cluster 400 million years old, farthest away of the three at 3700 light-years. More than 10 stars are visible in an amateur instrument in this cluster, of similar size to Dolidze 9 at 7 arcminutes in diameter, whose brightest star is of magnitude 7.5. It, too, has nebulosity in the east. Collinder 421 is a particularly old open cluster at an age of approximately 1 billion years; it is of magnitude 10.1. 3100 light-years from Earth, more than 30 stars are visible in a diameter of 8 arcseconds. The prominent star in the north of the cluster has a golden color, whereas the stars in the south of the cluster appear orange. Collinder 421 appears to be embedded in nebulosity, which extends past the cluster's borders to its west. Berkeley 90 is a smaller open cluster, with a diameter of 5 arcminutes. More than 16 members appear in an amateur telescope.
NGC 6826, the Blinking Planetary Nebula, is a planetary nebula with a magnitude of 8.5, 3200 light-years from Earth. It appears to "blink" in the eyepiece of a telescope because its central star is unusually bright (10th magnitude). When an observer focuses on the star, the nebula appears to fade away. Less than one degree from the Blinking Planetary is the double star 16 Cygni.
The North America Nebula (NGC 7000) is one of the most well-known nebulae in Cygnus, because it is visible to the unaided eye under dark skies, as a bright patch in the Milky Way. However, its characteristic shape is only visible in long-exposure photographs – it is difficult to observe in telescopes because of its low surface brightness. It has low surface brightness because it is so large; at its widest, the North America Nebula is 2 degrees across. Illuminated by a hot embedded star of magnitude 6, NGC 7000 is 1500 light-years from Earth.
To the south of Epsilon Cygni is the Veil Nebula (NGC 6960, 6979, 6992, and 6995), a 5,000-year-old supernova remnant covering approximately 3 degrees of the sky - it is over 50 light-years long. Because of its appearance, it is also called the Cygnus Loop. The Loop is only visible in long-exposure astrophotographs. However, the brightest portion, NGC 6992, is faintly visible in binoculars, and a dimmer portion, NGC 6960, is visible in wide-angle telescopes.
The DR 6 cluster is also nicknamed the "Galactic Ghoul" because of the nebula's resemblance to a human face;
The Gamma Cygni Nebula (IC 1318) includes both bright and dark nebulae in an area of over 4 degrees. DWB 87 is another of the many bright emission nebulae in Cygnus, 7.8 by 4.3 arcminutes. It is in the Gamma Cygni area. Two other emission nebulae include Sharpless 2-112 and Sharpless 2-115. When viewed in an amateur telescope, Sharpless 2–112 appears to be in a teardrop shape. More of the nebula's eastern portion is visible with an O III (doubly ionized oxygen) filter. There is an orange star of magnitude 10 nearby and a star of magnitude 9 near the nebula's northwest edge. Further to the northwest, there is a dark rift and another bright patch. The whole nebula measures 15 arcminutes in diameter. Sharpless 2–115 is another emission nebula with a complex pattern of light and dark patches. Two pairs of stars appear in the nebula; it is larger near the southwestern pair. The open cluster Berkeley 90 is embedded in this large nebula, which measures 30 by 20 arcminutes.
Also of note is the Crescent Nebula (NGC 6888), located between Gamma and Eta Cygni, which was formed by the Wolf–Rayet star HD 192163.
In recent years, amateur astronomers have made some notable Cygnus discoveries. The "Soap bubble nebula" (PN G75.5+1.7), near the Crescent nebula, was discovered on a digital image by Dave Jurasevich in 2007. In 2011, Austrian amateur Matthias Kronberger discovered a planetary nebula (Kronberger 61, now nicknamed "The Soccer Ball") on old survey photos, confirmed recently in images by the Gemini Observatory; both of these are likely too faint to be detected by eye in a small amateur scope.
But a much more obscure and relatively 'tiny' object—one which is readily seen in dark skies by amateur telescopes, under good conditions—is the newly discovered nebula (likely reflection type) associated with the star 4 Cygni (HD 183056): an approximately fan-shaped glowing region of several arcminutes' diameter, to the south and west of the fifth-magnitude star. It was first discovered visually near San Jose, California and publicly reported by amateur astronomer Stephen Waldee in 2007, and was confirmed photographically by Al Howard in 2010. California amateur astronomer Dana Patchick also says he detected it on the Palomar Observatory survey photos in 2005 but had not published it for others to confirm and analyze at the time of Waldee's first official notices and later 2010 paper.
Cygnus X is the largest star-forming region in the solar neighborhood and includes not only some of the brightest and most massive stars known (such as Cygnus OB2-12), but also Cygnus OB2, a massive stellar association classified by some authors as a young globular cluster.
Cygnus A is the first radio galaxy discovered; at a distance of 730 million light-years from Earth, it is the closest powerful radio galaxy. In the visible spectrum, it appears as an elliptical galaxy in a small cluster. It is classified as an active galaxy because the supermassive black hole at its nucleus is accreting matter, which produces two jets of matter from the poles. The jets' interaction with the interstellar medium creates radio lobes, one source of radio emissions.
Cygnus is also the apparent source of the WIMP-wind due to the orientation of the solar system's rotation through the galactic halo.
The local Orion-Cygnus Arm and the distant Cygnus Arm are two minor galactic arms named after Cygnus for lying in its background. | [
{
"paragraph_id": 0,
"text": "Cygnus is a northern constellation on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. Cygnus is one of the most recognizable constellations of the northern summer and autumn, and it features a prominent asterism known as the Northern Cross (in contrast to the Southern Cross). Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Cygnus contains Deneb (ذنب, translit. ḏanab, tail) – one of the brightest stars in the night sky and the most distant first-magnitude star – as its \"tail star\" and one corner of the Summer Triangle the constellation forming an east pointing altitude of the triangle. It also has some notable X-ray sources and the giant stellar association of Cygnus OB2. Cygnus is also known as the Northern Cross. One of the stars of this association, NML Cygni, is one of the largest stars currently known. The constellation is also home to Cygnus X-1, a distant X-ray binary containing a supergiant and unseen massive companion that was the first object widely held to be a black hole. Many star systems in Cygnus have known planets as a result of the Kepler Mission observing one patch of the sky, an area around Cygnus.",
"title": ""
},
{
"paragraph_id": 2,
"text": "Most of the east has part of the Hercules–Corona Borealis Great Wall in the deep sky, a giant galaxy filament that is the largest known structure in the observable universe, covering most of the northern sky.",
"title": ""
},
{
"paragraph_id": 3,
"text": "In Hinduism, the period of time (or Muhurta) between 4:24 AM to 5:12 AM is called the Brahmamuhurtha, which means \"the moment of the Universe\"; the star system in correlation is the Cygnus constellation. This is believed to be a highly auspicious time to meditate, do any task, or start the day.",
"title": "History and mythology"
},
{
"paragraph_id": 4,
"text": "In Polynesia, Cygnus was often recognized as a separate constellation. In Tonga it was called Tuula-lupe, and in the Tuamotus it was called Fanui-tai. In New Zealand it was called Mara-tea, in the Society Islands it was called Pirae-tea or Taurua-i-te-haapa-raa-manu, and in the Tuamotus it was called Fanui-raro. Beta Cygni was named in New Zealand; it was likely called Whetu-kaupo. Gamma Cygni was called Fanui-runga in the Tuamotus.",
"title": "History and mythology"
},
{
"paragraph_id": 5,
"text": "Deneb was also often a given name, in the Islamic world of astronomy. The name Deneb comes from the Arabic name dhaneb, meaning \"tail\", from the phrase Dhanab ad-Dajājah, which means \"the tail of the hen\".",
"title": "History and mythology"
},
{
"paragraph_id": 6,
"text": "In Greek mythology, Cygnus has been identified with several different legendary swans. Zeus disguised himself as a swan to seduce Leda, Spartan king Tyndareus's wife, who gave birth to the Gemini, Helen of Troy, and Clytemnestra; Orpheus was transformed into a swan after his murder, and was said to have been placed in the sky next to his lyre (Lyra); and the King Cygnus was transformed into a swan.",
"title": "History and mythology"
},
{
"paragraph_id": 7,
"text": "Later Romans also associated this constellation with the tragic story of Phaethon, the son of Helios the sun god, who demanded to ride his father's sun chariot for a day. Phaethon, however, was unable to control the reins, forcing Zeus to destroy the chariot (and Phaethon) with a thunderbolt, causing it to plummet to the earth into the river Eridanus. According to the myth, Phaethon's close friend or lover, Cygnus, grieved bitterly and spent many days diving into the river to collect Phaethon's bones to give him a proper burial. The gods were so touched by Cygnus's devotion that they turned him into a swan and placed him among the stars.",
"title": "History and mythology"
},
{
"paragraph_id": 8,
"text": "In Ovid's Metamorphoses, there are three people named Cygnus, all of whom are transformed into swans. Alongside Cygnus, noted above, he mentions a boy from Tempe who commits suicide when Phyllius refuses to give him a tamed bull that he demands, but is transformed into a swan and flies away. He also mentions a son of Neptune who is an invulnerable warrior in the Trojan War who is eventually defeated by Achilles, but Neptune saves him by transforming him into a swan.",
"title": "History and mythology"
},
{
"paragraph_id": 9,
"text": "Together with other avian constellations near the summer solstice, Vultur cadens and Aquila, Cygnus may be a significant part of the origin of the myth of the Stymphalian Birds, one of The Twelve Labours of Hercules.",
"title": "History and mythology"
},
{
"paragraph_id": 10,
"text": "A very large constellation, Cygnus is bordered by Cepheus to the north and east, Draco to the north and west, Lyra to the west, Vulpecula to the south, Pegasus to the southeast and Lacerta to the east. The three-letter abbreviation for the constellation, as adopted by the IAU in 1922, is \"Cyg\". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined as a polygon of 28 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 19 07.3 and 22 02.3 , while the declination coordinates are between 27.73° and 61.36°. Covering 804 square degrees and around 1.9% of the night sky, Cygnus ranks 16th of the 88 constellations in size.",
"title": "Characteristics"
},
{
"paragraph_id": 11,
"text": "Cygnus culminates at midnight on 29 June, and is most visible in the evening from the early summer to mid-autumn in the Northern Hemisphere.",
"title": "Characteristics"
},
{
"paragraph_id": 12,
"text": "Normally, Cygnus is depicted with Delta and Epsilon Cygni as its wings. Deneb, the brightest in the constellation is at its tail, and Albireo as the tip of its beak.",
"title": "Characteristics"
},
{
"paragraph_id": 13,
"text": "There are several asterisms in Cygnus. In the 17th-century German celestial cartographer Johann Bayer's star atlas the Uranometria, Alpha, Beta and Gamma Cygni form the pole of a cross, while Delta and Epsilon form the cross beam. The nova P Cygni was then considered to be the body of Christ.",
"title": "Characteristics"
},
{
"paragraph_id": 14,
"text": "There is an abundance of deep-sky objects, with many open clusters, nebulae of various types and supernova remnants found in Cygnus due to its position on the Milky Way.",
"title": "Features"
},
{
"paragraph_id": 15,
"text": "Its molecular clouds form the apparent Cygnus Rift dark nebula constellation, which is one end of the apparent part of the apparent Great Rift along the Milky Way's galactic plane. The rift begins with features like the Northern Coalsack which obscures the further away and large in apparent size Cygnus molecular cloud complex which the North America Nebula is part of.",
"title": "Features"
},
{
"paragraph_id": 16,
"text": "Bayer catalogued many stars in the constellation, giving them the Bayer designations from Alpha to Omega and then using lowercase Roman letters to g. John Flamsteed added the Roman letters h, i, k, l and m (these stars were considered informes by Bayer as they lay outside the asterism of Cygnus), but were dropped by Francis Baily.",
"title": "Features"
},
{
"paragraph_id": 17,
"text": "There are several bright stars in Cygnus. α Cygni, called Deneb, is the brightest star in Cygnus. It is a white supergiant star of spectral type A2Iae that varies between magnitudes 1.21 and 1.29, one of the largest and most luminous A-class stars known. It is located about 2600 light-years away. Its traditional name means \"tail\" and refers to its position in the constellation. Albireo, designated β Cygni, is a celebrated binary star among amateur astronomers for its contrasting hues. The primary is an orange-hued giant star of magnitude 3.1 and the secondary is a blue-green hued star of magnitude 5.1. The system is 430 light-years away and is visible in large binoculars and all amateur telescopes. γ Cygni, traditionally named Sadr, is a yellow-tinged supergiant star of magnitude 2.2, 1800 light-years away. Its traditional name means \"breast\" and refers to its position in the constellation. δ Cygni (the proper name is Fawaris) is another bright binary star in Cygnus, 166 light-years with a period of 800 years. The primary is a blue-white hued giant star of magnitude 2.9, and the secondary is a star of magnitude 6.6. The two components are visible in a medium-sized amateur telescope. The fifth star in Cygnus above magnitude 3 is Aljanah, designated ε Cygni. It is an orange-hued giant star of magnitude 2.5, 72 light-years from Earth.",
"title": "Features"
},
{
"paragraph_id": 18,
"text": "There are several other dimmer double and binary stars in Cygnus. μ Cygni is a binary star with an optical tertiary component. The binary system has a period of 790 years and is 73 light-years from Earth. The primary and secondary, both white stars, are of magnitude 4.8 and 6.2, respectively. The unrelated tertiary component is of magnitude 6.9. Though the tertiary component is visible in binoculars, the primary and secondary currently require a medium-sized amateur telescope to split, as they will through the year 2020. The two stars will be closest between 2043 and 2050, when they will require a telescope with larger aperture to split. The stars 30 and 31 Cygni form a contrasting double star similar to the brighter Albireo. The two are visible in binoculars. The primary, 31 Cygni, is an orange-hued star of magnitude 3.8, 1400 light-years from Earth. The secondary, 30 Cygni, appears blue-green. It is of spectral type A5IIIn and magnitude 4.83, and is around 610 light-years from Earth. 31 Cygni itself is a binary star; the tertiary component is a blue star of magnitude 7.0. ψ Cygni is a binary star visible in small amateur telescopes, with two white components. The primary is of magnitude 5.0 and the secondary is of magnitude 7.5. 61 Cygni is a binary star visible in large binoculars or a small amateur telescope. It is 11.4 light-years from Earth and has a period of 750 years. Both components are orange-hued dwarf (main sequence) stars; the primary is of magnitude 5.2 and the secondary is of magnitude 6.1. 61 Cygni is significant because Friedrich Wilhelm Bessel determined its parallax in 1838, the first star to have a known parallax.",
"title": "Features"
},
{
"paragraph_id": 19,
"text": "Located near η Cygni is the X-ray source Cygnus X-1, which is now thought to be caused by a black hole accreting matter in a binary star system. This was the first X-ray source widely believed to be a black hole. It is located approximately 2.2 kiloparsecs from the Sun. There is also supergiant variable star in the system which is known as HDE 226868.",
"title": "Features"
},
{
"paragraph_id": 20,
"text": "Cygnus also contains several other noteworthy X-ray sources. Cygnus X-3 is a microquasar containing a Wolf–Rayet star in orbit around a very compact object, with a period of only 4.8 hours. The system is one of the most intrinsically luminous X-ray sources observed. The system undergoes periodic outbursts of unknown nature, and during one such outburst, the system was found to be emitting muons, likely caused by neutrinos. While the compact object is thought to be a neutron star or possibly a black hole, it is possible that the object is instead a more exotic stellar remnant, possibly the first discovered quark star, hypothesized due to its production of cosmic rays that cannot be explained if the object is a normal neutron star. The system also emits cosmic rays and gamma rays, and has helped shed insight on to the formation of such rays. Cygnus X-2 is another X-ray binary, containing an A-type giant in orbit around a neutron star with a 9.8-day period. The system is interesting due to the rather small mass of the companion star, as most millisecond pulsars have much more massive companions. Another black hole in Cygnus is V404 Cygni, which consists of a K-type star orbiting around a black hole of around 12 solar masses. The black hole, similar to that of Cygnus X-3, has been hypothesized to be a quark star. 4U 2129+ 47 is another X-ray binary containing a neutron star which undergoes outbursts, as is EXO 2030+ 375.",
"title": "Features"
},
{
"paragraph_id": 21,
"text": "Cygnus is also home to several variable stars. SS Cygni is a dwarf nova which undergoes outbursts every 7–8 weeks. The system's total magnitude varies from 12th magnitude at its dimmest to 8th magnitude at its brightest. The two objects in the system are incredibly close together, with an orbital period of less than 0.28 days. χ Cygni is a red giant and the second-brightest Mira variable star at its maximum. It ranges between magnitudes 3.3 and 14.2, and spectral types S6,2e to S10,4e (MSe) over a period of 408 days; it has a diameter of 300 solar diameters and is 350 light-years from Earth. P Cygni is a luminous blue variable that brightened suddenly to 3rd magnitude in 1600 AD. Since 1715, the star has been of 5th magnitude, despite being more than 5000 light-years from Earth. The star's spectrum is unusual in that it contains very strong emission lines resulting from surrounding nebulosity. W Cygni is a semi-regular variable red giant star, 618 light-years from Earth.It has a maximum magnitude of 5.10 and a minimum magnitude 6.83; its period of 131 days. It is a red giant ranging between spectral types M4e-M6e(Tc:)III, NML Cygni is a red hypergiant semi-regular variable star located at 5,300 light-years away from Earth. It is one of largest stars currently known in the galaxy with a radius exceeding 1,000 solar radii. Its magnitude is around 16.6, its period is about 940 days.",
"title": "Features"
},
{
"paragraph_id": 22,
"text": "The star KIC 8462852 (Tabby's Star) has received widespread press coverage because of unusual light fluctuations.",
"title": "Features"
},
{
"paragraph_id": 23,
"text": "Cygnus is one of the constellations that the Kepler satellite surveyed in its search for exoplanets, and as a result, there are about a hundred stars in Cygnus with known planets, the most of any constellation. One of the most notable systems is the Kepler-11 system, containing six transiting planets, all within a plane of approximately one degree. It was the system with six exoplanets to be discovered. With a spectral type of G6V, the star is somewhat cooler than the Sun. The planets are very close to the star; all but the last planet are closer to Kepler-11 than Mercury is to the Sun, and all the planets are more massive than Earth, and have low densities. The planets have low densities. The naked-eye star 16 Cygni, a triple star approximately 70 light-years from Earth composed two Sun-like stars and a red dwarf, contains a planet orbiting one of the sun-like stars, found due to variations in the star's radial velocity. Gliese 777, another naked-eye multiple star system containing a yellow star and a red dwarf, also contains a planet. The planet is somewhat similar to Jupiter, but with slightly more mass and a more eccentric orbit. The Kepler-22 system is also notable for having the most Earth-like exoplanet when it was discovered in 2011.",
"title": "Features"
},
{
"paragraph_id": 24,
"text": "The rich background of stars of Cygnus can make it difficult to make out open cluster.",
"title": "Features"
},
{
"paragraph_id": 25,
"text": "M39 (NGC 7092) is an open cluster 950 light-years from Earth that are visible to the unaided eye under dark skies. It is loose, with about 30 stars arranged over a wide area; their conformation appears triangular. The brightest stars of M39 are of the 7th magnitude. Another open cluster in Cygnus is NGC 6910, also called the Rocking Horse Cluster, possessing 16 stars with a diameter of 5 arcminutes visible in a small amateur instrument; it is of magnitude 7.4. The brightest of these are two gold-hued stars, which represent the bottom of the toy it is named for. A larger amateur instrument reveals 8 more stars, nebulosity to the east and west of the cluster, and a diameter of 9 arcminutes. The nebulosity in this region is part of the Gamma Cygni Nebula. The other stars, approximately 3700 light-years from Earth, are mostly blue-white and very hot.",
"title": "Features"
},
{
"paragraph_id": 26,
"text": "Other open clusters in Cygnus include Dolidze 9, Collinder 421, Dolidze 11, and Berkeley 90. Dolidze 9, 2800 light-years from Earth and relatively young at 20 million light-years old, is a faint open cluster with up to 22 stars visible in small and medium-sized amateur telescopes. Nebulosity is visible to the north and east of the cluster, which is 7 arcminutes in diameter. The brightest star appears in the eastern part of the cluster and is of the 7th magnitude; another bright star has a yellow hue. Dolidze 11 is an open cluster 400 million years old, farthest away of the three at 3700 light-years. More than 10 stars are visible in an amateur instrument in this cluster, of similar size to Dolidze 9 at 7 arcminutes in diameter, whose brightest star is of magnitude 7.5. It, too, has nebulosity in the east. Collinder 421 is a particularly old open cluster at an age of approximately 1 billion years; it is of magnitude 10.1. 3100 light-years from Earth, more than 30 stars are visible in a diameter of 8 arcseconds. The prominent star in the north of the cluster has a golden color, whereas the stars in the south of the cluster appear orange. Collinder 421 appears to be embedded in nebulosity, which extends past the cluster's borders to its west. Berkeley 90 is a smaller open cluster, with a diameter of 5 arcminutes. More than 16 members appear in an amateur telescope.",
"title": "Features"
},
{
"paragraph_id": 27,
"text": "NGC 6826, the Blinking Planetary Nebula, is a planetary nebula with a magnitude of 8.5, 3200 light-years from Earth. It appears to \"blink\" in the eyepiece of a telescope because its central star is unusually bright (10th magnitude). When an observer focuses on the star, the nebula appears to fade away. Less than one degree from the Blinking Planetary is the double star 16 Cygni.",
"title": "Features"
},
{
"paragraph_id": 28,
"text": "The North America Nebula (NGC 7000) is one of the most well-known nebulae in Cygnus, because it is visible to the unaided eye under dark skies, as a bright patch in the Milky Way. However, its characteristic shape is only visible in long-exposure photographs – it is difficult to observe in telescopes because of its low surface brightness. It has low surface brightness because it is so large; at its widest, the North America Nebula is 2 degrees across. Illuminated by a hot embedded star of magnitude 6, NGC 7000 is 1500 light-years from Earth.",
"title": "Features"
},
{
"paragraph_id": 29,
"text": "To the south of Epsilon Cygni is the Veil Nebula (NGC 6960, 6979, 6992, and 6995), a 5,000-year-old supernova remnant covering approximately 3 degrees of the sky - it is over 50 light-years long. Because of its appearance, it is also called the Cygnus Loop. The Loop is only visible in long-exposure astrophotographs. However, the brightest portion, NGC 6992, is faintly visible in binoculars, and a dimmer portion, NGC 6960, is visible in wide-angle telescopes.",
"title": "Features"
},
{
"paragraph_id": 30,
"text": "The DR 6 cluster is also nicknamed the \"Galactic Ghoul\" because of the nebula's resemblance to a human face;",
"title": "Features"
},
{
"paragraph_id": 31,
"text": "The Gamma Cygni Nebula (IC 1318) includes both bright and dark nebulae in an area of over 4 degrees. DWB 87 is another of the many bright emission nebulae in Cygnus, 7.8 by 4.3 arcminutes. It is in the Gamma Cygni area. Two other emission nebulae include Sharpless 2-112 and Sharpless 2-115. When viewed in an amateur telescope, Sharpless 2–112 appears to be in a teardrop shape. More of the nebula's eastern portion is visible with an O III (doubly ionized oxygen) filter. There is an orange star of magnitude 10 nearby and a star of magnitude 9 near the nebula's northwest edge. Further to the northwest, there is a dark rift and another bright patch. The whole nebula measures 15 arcminutes in diameter. Sharpless 2–115 is another emission nebula with a complex pattern of light and dark patches. Two pairs of stars appear in the nebula; it is larger near the southwestern pair. The open cluster Berkeley 90 is embedded in this large nebula, which measures 30 by 20 arcminutes.",
"title": "Features"
},
{
"paragraph_id": 32,
"text": "Also of note is the Crescent Nebula (NGC 6888), located between Gamma and Eta Cygni, which was formed by the Wolf–Rayet star HD 192163.",
"title": "Features"
},
{
"paragraph_id": 33,
"text": "In recent years, amateur astronomers have made some notable Cygnus discoveries. The \"Soap bubble nebula\" (PN G75.5+1.7), near the Crescent nebula, was discovered on a digital image by Dave Jurasevich in 2007. In 2011, Austrian amateur Matthias Kronberger discovered a planetary nebula (Kronberger 61, now nicknamed \"The Soccer Ball\") on old survey photos, confirmed recently in images by the Gemini Observatory; both of these are likely too faint to be detected by eye in a small amateur scope.",
"title": "Features"
},
{
"paragraph_id": 34,
"text": "But a much more obscure and relatively 'tiny' object—one which is readily seen in dark skies by amateur telescopes, under good conditions—is the newly discovered nebula (likely reflection type) associated with the star 4 Cygni (HD 183056): an approximately fan-shaped glowing region of several arcminutes' diameter, to the south and west of the fifth-magnitude star. It was first discovered visually near San Jose, California and publicly reported by amateur astronomer Stephen Waldee in 2007, and was confirmed photographically by Al Howard in 2010. California amateur astronomer Dana Patchick also says he detected it on the Palomar Observatory survey photos in 2005 but had not published it for others to confirm and analyze at the time of Waldee's first official notices and later 2010 paper.",
"title": "Features"
},
{
"paragraph_id": 35,
"text": "Cygnus X is the largest star-forming region in the solar neighborhood and includes not only some of the brightest and most massive stars known (such as Cygnus OB2-12), but also Cygnus OB2, a massive stellar association classified by some authors as a young globular cluster.",
"title": "Features"
},
{
"paragraph_id": 36,
"text": "",
"title": "Features"
},
{
"paragraph_id": 37,
"text": "Cygnus A is the first radio galaxy discovered; at a distance of 730 million light-years from Earth, it is the closest powerful radio galaxy. In the visible spectrum, it appears as an elliptical galaxy in a small cluster. It is classified as an active galaxy because the supermassive black hole at its nucleus is accreting matter, which produces two jets of matter from the poles. The jets' interaction with the interstellar medium creates radio lobes, one source of radio emissions.",
"title": "Features"
},
{
"paragraph_id": 38,
"text": "Cygnus is also the apparent source of the WIMP-wind due to the orientation of the solar system's rotation through the galactic halo.",
"title": "Features"
},
{
"paragraph_id": 39,
"text": "The local Orion-Cygnus Arm and the distant Cygnus Arm are two minor galactic arms named after Cygnus for lying in its background.",
"title": "Features"
}
] | Cygnus is a northern constellation on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. Cygnus is one of the most recognizable constellations of the northern summer and autumn, and it features a prominent asterism known as the Northern Cross. Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations. Cygnus contains Deneb – one of the brightest stars in the night sky and the most distant first-magnitude star – as its "tail star" and one corner of the Summer Triangle the constellation forming an east pointing altitude of the triangle. It also has some notable X-ray sources and the giant stellar association of Cygnus OB2. Cygnus is also known as the Northern Cross. One of the stars of this association, NML Cygni, is one of the largest stars currently known. The constellation is also home to Cygnus X-1, a distant X-ray binary containing a supergiant and unseen massive companion that was the first object widely held to be a black hole. Many star systems in Cygnus have known planets as a result of the Kepler Mission observing one patch of the sky, an area around Cygnus. Most of the east has part of the Hercules–Corona Borealis Great Wall in the deep sky, a giant galaxy filament that is the largest known structure in the observable universe, covering most of the northern sky. | 2001-09-22T14:40:57Z | 2023-12-13T00:51:26Z | [
"Template:Use dmy dates",
"Template:See also",
"Template:Sfn",
"Template:RA",
"Template:ISBN",
"Template:Authority control",
"Template:Sky",
"Template:Stars of Cygnus",
"Template:Infobox constellation",
"Template:Clear",
"Template:Reflist",
"Template:Cite web",
"Template:Cite journal",
"Template:Cite news",
"Template:Citation",
"Template:Constellations",
"Template:Portal bar",
"Template:Short description",
"Template:Snd",
"Template:Cite APOD",
"Template:Cite book",
"Template:Commons and category",
"Template:Wikisource1911Enc"
] | https://en.wikipedia.org/wiki/Cygnus_(constellation) |
6,422 | Communion | Communion may refer to: | [
{
"paragraph_id": 0,
"text": "Communion may refer to:",
"title": ""
}
] | Communion may refer to: | 2001-09-17T18:46:00Z | 2023-12-26T11:01:09Z | [
"Template:Wiktionary",
"Template:TOC right",
"Template:Disambiguation"
] | https://en.wikipedia.org/wiki/Communion |
6,423 | Calorie | The calorie is a unit of energy that originated from the obsolete caloric theory of heat. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, dietary calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of one kilogram of water by one degree Celsius (or one kelvin). The small calorie or gram calorie was defined as the amount of heat needed to cause the same increase in one gram of water. Thus, 1 large calorie is equal to 1000 small calories.
In nutrition and food science, the term calorie and the symbol cal may refer to the large unit or to the small unit in different regions of the world. It is generally used in publications and package labels to express the energy value of foods in per serving or per weight, recommended dietary caloric intake, metabolic rates, etc. Some authors recommend the spelling Calorie and the symbol Cal (both with a capital C) if the large calorie is meant, to avoid confusion; however, this convention is often ignored.
In physics and chemistry the word calorie and its symbol usually refer to the small unit; the large one being called kilocalorie. However, this unit is not officially part of the metric system (SI), and is regarded as obsolete, having been replaced in many uses by the SI unit of energy, the joule (J).
The precise equivalence between calories and joules has varied over the years, but in thermochemistry and nutrition it is now generally assumed that one (small) calorie (thermochemical calorie) is equal to exactly 4.184 J, and therefore one kilocalorie (one large calorie) is 4184 J, or 4.184 kJ.
The term "calorie" was first introduced by Nicolas Clément, as a unit of heat energy, in lectures on experimental calorimetry during the years 1819–1824. This was the "large" calorie. The term (written with lowercase "c") entered French and English dictionaries between 1841 and 1867. It comes from Latin calor 'heat'.
The same term was used for the "small" unit by Pierre Antoine Favre (chemist) and Johann T. Silbermann (physicist) in 1852. This unit was used by U.S. physician Joseph Howard Raymond, in his classic 1894 textbook A Manual of Human Physiology. He proposed calling the "large" unit "kilocalorie", but the term did not catch on until some years later.
In 1879, Marcellin Berthelot distinguished between gram-calorie and kilogram-calorie, and proposed using "Calorie", with capital "C", for the large unit. This usage was adopted by Wilbur Olin Atwater, a professor at Wesleyan University, in 1887, in an influential article on the energy content of food.
The small calorie (cal) was recognized as a unit of the CGS system in 1896, alongside the already-existing CGS unit of energy, the erg (first suggested by Clausius in 1864, under the name ergon, and officially adopted in 1882).
Already in 1928 there were serious complaints about the possible confusion arising from the two main definitions of the calorie and whether the notion of using the capital letter to distinguish them was sound.
The joule was the officially adopted SI unit of energy at the ninth General Conference on Weights and Measures in 1948. The calorie was mentioned in the 7th edition of the SI brochure as an example of a non-SI unit.
The alternate spelling calory is considered nonstandard and dated.
The "small" calorie is broadly defined as the amount of energy needed to increase the temperature of 1 gram of water by 1 °C (or 1 K, which is the same increment, a gradation of one percent of the interval between the melting point and the boiling point of water). The actual amount of energy required to accomplish this temperature increase depends on the atmospheric pressure and the starting temperature; different choices of these parameters have resulted in several different precise definitions of the unit.
The two definitions most common in older literature appear to be the 15 °C calorie and the thermochemical calorie. Until 1948, the latter was defined as 4.1833 international joules; the current standard of 4.184 J was chosen to have the new thermochemical calorie represent the same quantity of energy as before.
In the United States, in a nutritional context, the "large" unit is used almost exclusively. It is generally written "calorie" with lowercase "c" and symbol "cal", even in government publications,. The SI unit of energy kilojoule (kJ) may be used instead, in legal or scientific contexts. Most nutritionists prefer the unit kilocalorie to the unit kilojoules, whereas most physiologists prefer to use kilojoules. In the majority of other countries, nutritionists prefer the kilojoule to the kilocalorie.
In the European Union, energy on nutrition facts labels is expressed in both kilojoules and kilocalories, abbreviated as "kJ" and "kcal" respectively.
In China, only kilojoules are given.
The unit is most commonly used to express food energy, namely the specific energy (energy per mass) of metabolizing different types of food. For example, fat (lipids) contains 9 kilocalories per gram (kcal/g), while carbohydrates (sugar and starch) and protein contain approximately 4 kcal/g. Alcohol in food contains 7 kcal/g. The "large" unit is also used to express recommended nutritional intake or consumption, as in "calories per day".
Dieting is the practice of eating food in a regulated way to decrease, maintain, or increase body weight, or to prevent and treat diseases such as diabetes and obesity. As weight loss depends on reducing caloric intake, different kinds of calorie-reduced diets have been shown to be generally effective.
In other scientific contexts, the term "calorie" and the symbol "cal" almost always refers to the small unit; the "large" unit being generally called "kilocalorie" with symbol "kcal". It is mostly used to express the amount of energy released in a chemical reaction or phase change, typically per mole of substance, as in kilocalories per mole. It is also occasionally used to specify other energy quantities that relate to reaction energy, such as enthalpy of formation and the size of activation barriers. However, it is increasingly being superseded by the SI unit, the joule (J); and metric multiples thereof, such as the kilojoule (kJ).
The lingering use in chemistry is largely due to the fact that the energy released by a reaction in aqueous solution, expressed in kilocalories per mole of reagent, is numerically close to the concentration of the reagent, in moles per liter, multiplied by the change in the temperature of the solution, in kelvin or degrees Celsius. However, this estimate assumes that the volumetric heat capacity of the solution is 1 kcal/L/K, which is not exact even for pure water. | [
{
"paragraph_id": 0,
"text": "The calorie is a unit of energy that originated from the obsolete caloric theory of heat. For historical reasons, two main definitions of \"calorie\" are in wide use. The large calorie, food calorie, dietary calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of one kilogram of water by one degree Celsius (or one kelvin). The small calorie or gram calorie was defined as the amount of heat needed to cause the same increase in one gram of water. Thus, 1 large calorie is equal to 1000 small calories.",
"title": ""
},
{
"paragraph_id": 1,
"text": "In nutrition and food science, the term calorie and the symbol cal may refer to the large unit or to the small unit in different regions of the world. It is generally used in publications and package labels to express the energy value of foods in per serving or per weight, recommended dietary caloric intake, metabolic rates, etc. Some authors recommend the spelling Calorie and the symbol Cal (both with a capital C) if the large calorie is meant, to avoid confusion; however, this convention is often ignored.",
"title": ""
},
{
"paragraph_id": 2,
"text": "In physics and chemistry the word calorie and its symbol usually refer to the small unit; the large one being called kilocalorie. However, this unit is not officially part of the metric system (SI), and is regarded as obsolete, having been replaced in many uses by the SI unit of energy, the joule (J).",
"title": ""
},
{
"paragraph_id": 3,
"text": "The precise equivalence between calories and joules has varied over the years, but in thermochemistry and nutrition it is now generally assumed that one (small) calorie (thermochemical calorie) is equal to exactly 4.184 J, and therefore one kilocalorie (one large calorie) is 4184 J, or 4.184 kJ.",
"title": ""
},
{
"paragraph_id": 4,
"text": "The term \"calorie\" was first introduced by Nicolas Clément, as a unit of heat energy, in lectures on experimental calorimetry during the years 1819–1824. This was the \"large\" calorie. The term (written with lowercase \"c\") entered French and English dictionaries between 1841 and 1867. It comes from Latin calor 'heat'.",
"title": "History"
},
{
"paragraph_id": 5,
"text": "The same term was used for the \"small\" unit by Pierre Antoine Favre (chemist) and Johann T. Silbermann (physicist) in 1852. This unit was used by U.S. physician Joseph Howard Raymond, in his classic 1894 textbook A Manual of Human Physiology. He proposed calling the \"large\" unit \"kilocalorie\", but the term did not catch on until some years later.",
"title": "History"
},
{
"paragraph_id": 6,
"text": "In 1879, Marcellin Berthelot distinguished between gram-calorie and kilogram-calorie, and proposed using \"Calorie\", with capital \"C\", for the large unit. This usage was adopted by Wilbur Olin Atwater, a professor at Wesleyan University, in 1887, in an influential article on the energy content of food.",
"title": "History"
},
{
"paragraph_id": 7,
"text": "The small calorie (cal) was recognized as a unit of the CGS system in 1896, alongside the already-existing CGS unit of energy, the erg (first suggested by Clausius in 1864, under the name ergon, and officially adopted in 1882).",
"title": "History"
},
{
"paragraph_id": 8,
"text": "Already in 1928 there were serious complaints about the possible confusion arising from the two main definitions of the calorie and whether the notion of using the capital letter to distinguish them was sound.",
"title": "History"
},
{
"paragraph_id": 9,
"text": "The joule was the officially adopted SI unit of energy at the ninth General Conference on Weights and Measures in 1948. The calorie was mentioned in the 7th edition of the SI brochure as an example of a non-SI unit.",
"title": "History"
},
{
"paragraph_id": 10,
"text": "The alternate spelling calory is considered nonstandard and dated.",
"title": "History"
},
{
"paragraph_id": 11,
"text": "The \"small\" calorie is broadly defined as the amount of energy needed to increase the temperature of 1 gram of water by 1 °C (or 1 K, which is the same increment, a gradation of one percent of the interval between the melting point and the boiling point of water). The actual amount of energy required to accomplish this temperature increase depends on the atmospheric pressure and the starting temperature; different choices of these parameters have resulted in several different precise definitions of the unit.",
"title": "Definitions"
},
{
"paragraph_id": 12,
"text": "The two definitions most common in older literature appear to be the 15 °C calorie and the thermochemical calorie. Until 1948, the latter was defined as 4.1833 international joules; the current standard of 4.184 J was chosen to have the new thermochemical calorie represent the same quantity of energy as before.",
"title": "Definitions"
},
{
"paragraph_id": 13,
"text": "In the United States, in a nutritional context, the \"large\" unit is used almost exclusively. It is generally written \"calorie\" with lowercase \"c\" and symbol \"cal\", even in government publications,. The SI unit of energy kilojoule (kJ) may be used instead, in legal or scientific contexts. Most nutritionists prefer the unit kilocalorie to the unit kilojoules, whereas most physiologists prefer to use kilojoules. In the majority of other countries, nutritionists prefer the kilojoule to the kilocalorie.",
"title": "Usage"
},
{
"paragraph_id": 14,
"text": "In the European Union, energy on nutrition facts labels is expressed in both kilojoules and kilocalories, abbreviated as \"kJ\" and \"kcal\" respectively.",
"title": "Usage"
},
{
"paragraph_id": 15,
"text": "In China, only kilojoules are given.",
"title": "Usage"
},
{
"paragraph_id": 16,
"text": "The unit is most commonly used to express food energy, namely the specific energy (energy per mass) of metabolizing different types of food. For example, fat (lipids) contains 9 kilocalories per gram (kcal/g), while carbohydrates (sugar and starch) and protein contain approximately 4 kcal/g. Alcohol in food contains 7 kcal/g. The \"large\" unit is also used to express recommended nutritional intake or consumption, as in \"calories per day\".",
"title": "Usage"
},
{
"paragraph_id": 17,
"text": "Dieting is the practice of eating food in a regulated way to decrease, maintain, or increase body weight, or to prevent and treat diseases such as diabetes and obesity. As weight loss depends on reducing caloric intake, different kinds of calorie-reduced diets have been shown to be generally effective.",
"title": "Usage"
},
{
"paragraph_id": 18,
"text": "In other scientific contexts, the term \"calorie\" and the symbol \"cal\" almost always refers to the small unit; the \"large\" unit being generally called \"kilocalorie\" with symbol \"kcal\". It is mostly used to express the amount of energy released in a chemical reaction or phase change, typically per mole of substance, as in kilocalories per mole. It is also occasionally used to specify other energy quantities that relate to reaction energy, such as enthalpy of formation and the size of activation barriers. However, it is increasingly being superseded by the SI unit, the joule (J); and metric multiples thereof, such as the kilojoule (kJ).",
"title": "Usage"
},
{
"paragraph_id": 19,
"text": "The lingering use in chemistry is largely due to the fact that the energy released by a reaction in aqueous solution, expressed in kilocalories per mole of reagent, is numerically close to the concentration of the reagent, in moles per liter, multiplied by the change in the temperature of the solution, in kelvin or degrees Celsius. However, this estimate assumes that the volumetric heat capacity of the solution is 1 kcal/L/K, which is not exact even for pure water.",
"title": "Usage"
}
] | The calorie is a unit of energy that originated from the obsolete caloric theory of heat. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, dietary calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of one kilogram of water by one degree Celsius. The small calorie or gram calorie was defined as the amount of heat needed to cause the same increase in one gram of water. Thus, 1 large calorie is equal to 1000 small calories. In nutrition and food science, the term calorie and the symbol cal may refer to the large unit or to the small unit in different regions of the world. It is generally used in publications and package labels to express the energy value of foods in per serving or per weight, recommended dietary caloric intake, metabolic rates, etc. Some authors recommend the spelling Calorie and the symbol Cal if the large calorie is meant, to avoid confusion; however, this convention is often ignored. In physics and chemistry the word calorie and its symbol usually refer to the small unit; the large one being called kilocalorie. However, this unit is not officially part of the metric system (SI), and is regarded as obsolete, having been replaced in many uses by the SI unit of energy, the joule (J). The precise equivalence between calories and joules has varied over the years, but in thermochemistry and nutrition it is now generally assumed that one (small) calorie is equal to exactly 4.184 J, and therefore one kilocalorie is 4184 J, or 4.184 kJ. | 2001-10-28T14:28:17Z | 2023-12-09T07:31:04Z | [
"Template:Val",
"Template:Cn",
"Template:Ety",
"Template:Notelist",
"Template:Cite journal",
"Template:Short description",
"Template:Hatnote",
"Template:Convert",
"Template:Linktext",
"Template:Reflist",
"Template:Efn",
"Template:Frac",
"Template:Portal",
"Template:Div col",
"Template:Div col end",
"Template:Cite web"
] | https://en.wikipedia.org/wiki/Calorie |
6,424 | Corona Australis | Corona Australis is a constellation in the Southern Celestial Hemisphere. Its Latin name means "southern crown", and it is the southern counterpart of Corona Borealis, the northern crown. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. The Ancient Greeks saw Corona Australis as a wreath rather than a crown and associated it with Sagittarius or Centaurus. Other cultures have likened the pattern to a turtle, ostrich nest, a tent, or even a hut belonging to a rock hyrax.
Although fainter than its northern counterpart, the oval- or horseshoe-shaped pattern of its brighter stars renders it distinctive. Alpha and Beta Coronae Australis are the two brightest stars with an apparent magnitude of around 4.1. Epsilon Coronae Australis is the brightest example of a W Ursae Majoris variable in the southern sky. Lying alongside the Milky Way, Corona Australis contains one of the closest star-forming regions to the Solar System—a dusty dark nebula known as the Corona Australis Molecular Cloud, lying about 430 light years away. Within it are stars at the earliest stages of their lifespan. The variable stars R and TY Coronae Australis light up parts of the nebula, which varies in brightness accordingly.
The name of the constellation was entered as "Corona Australis" when the International Astronomical Union (IAU) established the 88 modern constellations in 1922. In 1932, the name was instead recorded as "Corona Austrina" when the IAU's commission on notation approved a list of four-letter abbreviations for the constellations. The four-letter abbreviations were repealed in 1955. The IAU presently uses "Corona Australis" exclusively.
Corona Australis is a small constellation bordered by Sagittarius to the north, Scorpius to the west, Telescopium to the south, and Ara to the southwest. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "CrA". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of four segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between 17 58.3 and 19 19.0 , while the declination coordinates are between −36.77° and −45.52°. Covering 128 square degrees, Corona Australis culminates at midnight around the 30th of June and ranks 80th in area. Only visible at latitudes south of 53° north, Corona Australis cannot be seen from the British Isles as it lies too far south, but it can be seen from southern Europe and readily from the southern United States.
While not a bright constellation, Corona Australis is nonetheless distinctive due to its easily identifiable pattern of stars, which has been described as horseshoe- or oval-shaped. Though it has no stars brighter than 4th magnitude, it still has 21 stars visible to the unaided eye (brighter than magnitude 5.5). Nicolas Louis de Lacaille used the Greek letters Alpha through to Lambda to label the most prominent eleven stars in the constellation, designating two stars as Eta and omitting Iota altogether. Mu Coronae Australis, a yellow star of spectral type G5.5III and apparent magnitude 5.21, was labelled by Johann Elert Bode and retained by Benjamin Gould, who deemed it bright enough to warrant naming.
The only star in the constellation to have received a name is Alfecca Meridiana or Alpha CrA. The name combines the Arabic name of the constellation with the Latin for "southern". In Arabic, Alfecca means "break", and refers to the shape of both Corona Australis and Corona Borealis. Also called simply "Meridiana", it is a white main sequence star located 125 light years away from Earth, with an apparent magnitude of 4.10 and spectral type A2Va. A rapidly rotating star, it spins at almost 200 km per second at its equator, making a complete revolution in around 14 hours. Like the star Vega, it has excess infrared radiation, which indicates it may be ringed by a disk of dust. It is currently a main-sequence star, but will eventually evolve into a white dwarf; currently, it has a luminosity 31 times greater, and a radius and mass of 2.3 times that of the Sun. Beta Coronae Australis is an orange giant 474 light years from Earth. Its spectral type is K0II, and it is of apparent magnitude 4.11. Since its formation, it has evolved from a B-type star to a K-type star. Its luminosity class places it as a bright giant; its luminosity is 730 times that of the Sun, designating it one of the highest-luminosity K0-type stars visible to the naked eye. 100 million years old, it has a radius of 43 solar radii (R☉) and a mass of between 4.5 and 5 solar masses (M☉). Alpha and Beta are so similar as to be indistinguishable in brightness to the naked eye.
Some of the more prominent double stars include Gamma Coronae Australis—a pair of yellowish white stars 58 light years away from Earth, which orbit each other every 122 years. Widening since 1990, the two stars can be seen as separate with a 100 mm aperture telescope; they are separated by 1.3 arcseconds at an angle of 61 degrees. They have a combined visual magnitude of 4.2; each component is an F8V dwarf star with a magnitude of 5.01. Epsilon Coronae Australis is an eclipsing binary belonging to a class of stars known as W Ursae Majoris variables. These star systems are known as contact binaries as the component stars are so close together they touch. Varying by a quarter of a magnitude around an average apparent magnitude of 4.83 every seven hours, the star system lies 98 light years away. Its spectral type is F4VFe-0.8+. At the southern end of the crown asterism are the stars Eta and Eta CrA, which form an optical double. Of magnitude 5.1 and 5.5, they are separable with the naked eye and are both white. Kappa Coronae Australis is an easily resolved optical double—the components are of apparent magnitudes 6.3 and 5.6 and are about 1000 and 150 light years away respectively. They appear at an angle of 359 degrees, separated by 21.6 arcseconds. Kappa is actually the brighter of the pair and is more bluish white, with a spectral type of B9V, while Kappa is of spectral type A0III. Lying 202 light years away, Lambda Coronae Australis is a double splittable in small telescopes. The primary is a white star of spectral type A2Vn and magnitude of 5.1, while the companion star has a magnitude of 9.7. The two components are separated by 29.2 arcseconds at an angle of 214 degrees.
Zeta Coronae Australis is a rapidly rotating main sequence star with an apparent magnitude of 4.8, 221.7 light years from Earth. The star has blurred lines in its hydrogen spectrum due to its rotation. Its spectral type is B9V. Theta Coronae Australis lies further to the west, a yellow giant of spectral type G8III and apparent magnitude 4.62. Corona Australis harbours RX J1856.5-3754, an isolated neutron star that is thought to lie 140 (±40) parsecs, or 460 (±130) light years, away, with a diameter of 14 km. It was once suspected to be a strange star, but this has been discounted.
The Corona Australis Molecular Cloud is a dark molecular cloud just north of Beta Coronae Australis. Illuminated by a number of embedded reflection nebulae the cloud fans out from Epsilon Coronae Australis eastward along the constellation border with Sagittarius. It contains 7000 M☉, Herbig–Haro objects (protostars) and some very young stars, being one of the closest star-forming regions, 430 light years (130 parsecs) to the Solar System, at the surface of the Local Bubble. The first nebulae of the cloud were recorded in 1865 by Johann Friedrich Julius Schmidt.
Between Epsilon and Gamma Coronae Australis the cloud consists of the particular dark nebula and star forming region Bernes 157. It is 55 by 18 arcminutes wide and possesses several stars around magnitude 13. These stars are dimmed by up to 8 magnitudes because of the obscuring dust clouds. At the center of the active star-forming region lies the Coronet cluster (also called R CrA Cluster), which is used in studying star and protoplanetary disk formation. R Coronae Australis (R CrA) is an irregular variable star ranging from magnitudes 9.7 to 13.9. Blue-white, it is of spectral type B5IIIpe. A very young star, it is still accumulating interstellar material. It is obscured by, and illuminates, the surrounding nebula, NGC 6729, which brightens and darkens with it. The nebula is often compared to a comet for its appearance in a telescope, as its length is five times its width. Other stars of the cluster include S Coronae Australis, a G-class dwarf and T Tauri star.
Nearby north, another young variable star, TY Coronae Australis, illuminates another nebula: reflection nebula NGC 6726/NGC 6727. TY Coronae Australis ranges irregularly between magnitudes 8.7 and 12.4, and the brightness of the nebula varies with it. Blue-white, it is of spectral type B8e. The largest young stars in the region, R, S, T, TY and VV Coronae Australis, are all ejecting jets of material which cause surrounding dust and gas to coalesce and form Herbig–Haro objects, many of which have been identified nearby.
Not part of it is the globular cluster known as NGC 6723, which can be seen adjacent to the nebulosity in the neighbouring constellation of Sagittarius, but is much much further away.
IC 1297 is a planetary nebula of apparent magnitude 10.7, which appears as a green-hued roundish object in higher-powered amateur instruments. The nebula surrounds the variable star RU Coronae Australis, which has an average apparent magnitude of 12.9 and is a WC class Wolf–Rayet star. IC 1297 is small, at only 7 arcseconds in diameter; it has been described as "a square with rounded edges" in the eyepiece, elongated in the north–south direction. Descriptions of its color encompass blue, blue-tinged green, and green-tinged blue.
Corona Australis' location near the Milky Way means that galaxies are uncommonly seen. NGC 6768 is a magnitude 11.2 object 35′ south of IC 1297. It is made up of two galaxies merging, one of which is an elongated elliptical galaxy of classification E4 and the other a lenticular galaxy of classification S0. IC 4808 is a galaxy of apparent magnitude 12.9 located on the border of Corona Australis with the neighbouring constellation of Telescopium and 3.9 degrees west-southwest of Beta Sagittarii. However, amateur telescopes will only show a suggestion of its spiral structure. It is 1.9 arcminutes by 0.8 arcminutes. The central area of the galaxy does appear brighter in an amateur instrument, which shows it to be tilted northeast–southwest.
Southeast of Theta and southwest of Eta lies the open cluster ESO 281-SC24, which is composed of the yellow 9th magnitude star GSC 7914 178 1 and five 10th to 11th magnitude stars. Halfway between Theta Coronae Australis and Theta Scorpii is the dense globular cluster NGC 6541. Described as between magnitude 6.3 and magnitude 6.6, it is visible in binoculars and small telescopes. Around 22000 light years away, it is around 100 light years in diameter. It is estimated to be around 14 billion years old. NGC 6541 appears 13.1 arcminutes in diameter and is somewhat resolvable in large amateur instruments; a 12-inch telescope reveals approximately 100 stars but the core remains unresolved.
The Corona Australids are a meteor shower that takes place between 14 and 18 March each year, peaking around 16 March. This meteor shower does not have a high peak hourly rate. In 1953 and 1956, observers noted a maximum of 6 meteors per hour and 4 meteors per hour respectively; in 1955 the shower was "barely resolved". However, in 1992, astronomers detected a peak rate of 45 meteors per hour. The Corona Australids' rate varies from year to year. At only six days, the shower's duration is particularly short, and its meteoroids are small; the stream is devoid of large meteoroids. The Corona Australids were first seen with the unaided eye in 1935 and first observed with radar in 1955. Corona Australid meteors have an entry velocity of 45 kilometers per second. In 2006, a shower originating near Beta Coronae Australis was designated as the Beta Coronae Australids. They appear in May, the same month as a nearby shower known as the May Microscopids, but the two showers have different trajectories and are unlikely to be related.
Corona Australis may have been recorded by ancient Mesopotamians in the MUL.APIN, as a constellation called MA.GUR ("The Bark"). However, this constellation, adjacent to SUHUR.MASH ("The Goat-Fish", modern Capricornus), may instead have been modern Epsilon Sagittarii. As a part of the southern sky, MA.GUR was one of the fifteen "stars of Ea".
In the 3rd century BC, the Greek didactic poet Aratus wrote of, but did not name the constellation, instead calling the two crowns Στεφάνοι (Stephanoi). The Greek astronomer Ptolemy described the constellation in the 2nd century AD, though with the inclusion of Alpha Telescopii, since transferred to Telescopium. Ascribing 13 stars to the constellation, he named it Στεφάνος νοτιος (Stephanos notios), "Southern Wreath", while other authors associated it with either Sagittarius (having fallen off his head) or Centaurus; with the former, it was called Corona Sagittarii. Similarly, the Romans called Corona Australis the "Golden Crown of Sagittarius". It was known as Parvum Coelum ("Canopy", "Little Sky") in the 5th century. The 18th-century French astronomer Jérôme Lalande gave it the names Sertum Australe ("Southern Garland") and Orbiculus Capitis, while German poet and author Philippus Caesius called it Corolla ("Little Crown") or Spira Australis ("Southern Coil"), and linked it with the Crown of Eternal Life from the New Testament. Seventeenth-century celestial cartographer Julius Schiller linked it to the Diadem of Solomon. Sometimes, Corona Australis was not the wreath of Sagittarius but arrows held in his hand.
Corona Australis has been associated with the myth of Bacchus and Stimula. Jupiter had impregnated Stimula, causing Juno to become jealous. Juno convinced Stimula to ask Jupiter to appear in his full splendor, which the mortal woman could not handle, causing her to burn. After Bacchus, Stimula's unborn child, became an adult and the god of wine, he honored his deceased mother by placing a wreath in the sky.
In Chinese astronomy, the stars of Corona Australis are located within the Black Tortoise of the North (北方玄武, Běi Fāng Xuán Wǔ). The constellation itself was known as ti'en pieh ("Heavenly Turtle") and during the Western Zhou period, marked the beginning of winter. However, precession over time has meant that the "Heavenly River" (Milky Way) became the more accurate marker to the ancient Chinese and hence supplanted the turtle in this role. Arabic names for Corona Australis include Al Ķubbah "the Tortoise", Al Ĥibā "the Tent" or Al Udḥā al Na'ām "the Ostrich Nest". It was later given the name Al Iklīl al Janūbiyyah, which the European authors Chilmead, Riccioli and Caesius transliterated as Alachil Elgenubi, Elkleil Elgenubi and Aladil Algenubi respectively.
The ǀXam speaking San people of South Africa knew the constellation as ≠nabbe ta !nu "house of branches"—owned originally by the Dassie (rock hyrax), and the star pattern depicting people sitting in a semicircle around a fire.
The indigenous Boorong people of northwestern Victoria saw it as Won, a boomerang thrown by Totyarguil (Altair). The Aranda people of Central Australia saw Corona Australis as a coolamon carrying a baby, which was accidentally dropped to earth by a group of sky-women dancing in the Milky Way. The impact of the coolamon created Gosses Bluff crater, 175 km west of Alice Springs. The Torres Strait Islanders saw Corona Australis as part of a larger constellation encompassing part of Sagittarius and the tip of Scorpius's tail; the Pleiades and Orion were also associated. This constellation was Tagai's canoe, crewed by the Pleiades, called the Usiam, and Orion, called the Seg. The myth of Tagai says that he was in charge of this canoe, but his crewmen consumed all of the supplies onboard without asking permission. Enraged, Tagai bound the Usiam with a rope and tied them to the side of the boat, then threw them overboard. Scorpius's tail represents a suckerfish, while Eta Sagittarii and Theta Coronae Australis mark the bottom of the canoe. On the island of Futuna, the figure of Corona Australis was called Tanuma and in the Tuamotus, it was called Na Kaua-ki-Tonga.
SIMBAD | [
{
"paragraph_id": 0,
"text": "Corona Australis is a constellation in the Southern Celestial Hemisphere. Its Latin name means \"southern crown\", and it is the southern counterpart of Corona Borealis, the northern crown. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. The Ancient Greeks saw Corona Australis as a wreath rather than a crown and associated it with Sagittarius or Centaurus. Other cultures have likened the pattern to a turtle, ostrich nest, a tent, or even a hut belonging to a rock hyrax.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Although fainter than its northern counterpart, the oval- or horseshoe-shaped pattern of its brighter stars renders it distinctive. Alpha and Beta Coronae Australis are the two brightest stars with an apparent magnitude of around 4.1. Epsilon Coronae Australis is the brightest example of a W Ursae Majoris variable in the southern sky. Lying alongside the Milky Way, Corona Australis contains one of the closest star-forming regions to the Solar System—a dusty dark nebula known as the Corona Australis Molecular Cloud, lying about 430 light years away. Within it are stars at the earliest stages of their lifespan. The variable stars R and TY Coronae Australis light up parts of the nebula, which varies in brightness accordingly.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The name of the constellation was entered as \"Corona Australis\" when the International Astronomical Union (IAU) established the 88 modern constellations in 1922. In 1932, the name was instead recorded as \"Corona Austrina\" when the IAU's commission on notation approved a list of four-letter abbreviations for the constellations. The four-letter abbreviations were repealed in 1955. The IAU presently uses \"Corona Australis\" exclusively.",
"title": "Name"
},
{
"paragraph_id": 3,
"text": "Corona Australis is a small constellation bordered by Sagittarius to the north, Scorpius to the west, Telescopium to the south, and Ara to the southwest. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is \"CrA\". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of four segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between 17 58.3 and 19 19.0 , while the declination coordinates are between −36.77° and −45.52°. Covering 128 square degrees, Corona Australis culminates at midnight around the 30th of June and ranks 80th in area. Only visible at latitudes south of 53° north, Corona Australis cannot be seen from the British Isles as it lies too far south, but it can be seen from southern Europe and readily from the southern United States.",
"title": "Characteristics"
},
{
"paragraph_id": 4,
"text": "While not a bright constellation, Corona Australis is nonetheless distinctive due to its easily identifiable pattern of stars, which has been described as horseshoe- or oval-shaped. Though it has no stars brighter than 4th magnitude, it still has 21 stars visible to the unaided eye (brighter than magnitude 5.5). Nicolas Louis de Lacaille used the Greek letters Alpha through to Lambda to label the most prominent eleven stars in the constellation, designating two stars as Eta and omitting Iota altogether. Mu Coronae Australis, a yellow star of spectral type G5.5III and apparent magnitude 5.21, was labelled by Johann Elert Bode and retained by Benjamin Gould, who deemed it bright enough to warrant naming.",
"title": "Features"
},
{
"paragraph_id": 5,
"text": "The only star in the constellation to have received a name is Alfecca Meridiana or Alpha CrA. The name combines the Arabic name of the constellation with the Latin for \"southern\". In Arabic, Alfecca means \"break\", and refers to the shape of both Corona Australis and Corona Borealis. Also called simply \"Meridiana\", it is a white main sequence star located 125 light years away from Earth, with an apparent magnitude of 4.10 and spectral type A2Va. A rapidly rotating star, it spins at almost 200 km per second at its equator, making a complete revolution in around 14 hours. Like the star Vega, it has excess infrared radiation, which indicates it may be ringed by a disk of dust. It is currently a main-sequence star, but will eventually evolve into a white dwarf; currently, it has a luminosity 31 times greater, and a radius and mass of 2.3 times that of the Sun. Beta Coronae Australis is an orange giant 474 light years from Earth. Its spectral type is K0II, and it is of apparent magnitude 4.11. Since its formation, it has evolved from a B-type star to a K-type star. Its luminosity class places it as a bright giant; its luminosity is 730 times that of the Sun, designating it one of the highest-luminosity K0-type stars visible to the naked eye. 100 million years old, it has a radius of 43 solar radii (R☉) and a mass of between 4.5 and 5 solar masses (M☉). Alpha and Beta are so similar as to be indistinguishable in brightness to the naked eye.",
"title": "Features"
},
{
"paragraph_id": 6,
"text": "Some of the more prominent double stars include Gamma Coronae Australis—a pair of yellowish white stars 58 light years away from Earth, which orbit each other every 122 years. Widening since 1990, the two stars can be seen as separate with a 100 mm aperture telescope; they are separated by 1.3 arcseconds at an angle of 61 degrees. They have a combined visual magnitude of 4.2; each component is an F8V dwarf star with a magnitude of 5.01. Epsilon Coronae Australis is an eclipsing binary belonging to a class of stars known as W Ursae Majoris variables. These star systems are known as contact binaries as the component stars are so close together they touch. Varying by a quarter of a magnitude around an average apparent magnitude of 4.83 every seven hours, the star system lies 98 light years away. Its spectral type is F4VFe-0.8+. At the southern end of the crown asterism are the stars Eta and Eta CrA, which form an optical double. Of magnitude 5.1 and 5.5, they are separable with the naked eye and are both white. Kappa Coronae Australis is an easily resolved optical double—the components are of apparent magnitudes 6.3 and 5.6 and are about 1000 and 150 light years away respectively. They appear at an angle of 359 degrees, separated by 21.6 arcseconds. Kappa is actually the brighter of the pair and is more bluish white, with a spectral type of B9V, while Kappa is of spectral type A0III. Lying 202 light years away, Lambda Coronae Australis is a double splittable in small telescopes. The primary is a white star of spectral type A2Vn and magnitude of 5.1, while the companion star has a magnitude of 9.7. The two components are separated by 29.2 arcseconds at an angle of 214 degrees.",
"title": "Features"
},
{
"paragraph_id": 7,
"text": "Zeta Coronae Australis is a rapidly rotating main sequence star with an apparent magnitude of 4.8, 221.7 light years from Earth. The star has blurred lines in its hydrogen spectrum due to its rotation. Its spectral type is B9V. Theta Coronae Australis lies further to the west, a yellow giant of spectral type G8III and apparent magnitude 4.62. Corona Australis harbours RX J1856.5-3754, an isolated neutron star that is thought to lie 140 (±40) parsecs, or 460 (±130) light years, away, with a diameter of 14 km. It was once suspected to be a strange star, but this has been discounted.",
"title": "Features"
},
{
"paragraph_id": 8,
"text": "The Corona Australis Molecular Cloud is a dark molecular cloud just north of Beta Coronae Australis. Illuminated by a number of embedded reflection nebulae the cloud fans out from Epsilon Coronae Australis eastward along the constellation border with Sagittarius. It contains 7000 M☉, Herbig–Haro objects (protostars) and some very young stars, being one of the closest star-forming regions, 430 light years (130 parsecs) to the Solar System, at the surface of the Local Bubble. The first nebulae of the cloud were recorded in 1865 by Johann Friedrich Julius Schmidt.",
"title": "Features"
},
{
"paragraph_id": 9,
"text": "Between Epsilon and Gamma Coronae Australis the cloud consists of the particular dark nebula and star forming region Bernes 157. It is 55 by 18 arcminutes wide and possesses several stars around magnitude 13. These stars are dimmed by up to 8 magnitudes because of the obscuring dust clouds. At the center of the active star-forming region lies the Coronet cluster (also called R CrA Cluster), which is used in studying star and protoplanetary disk formation. R Coronae Australis (R CrA) is an irregular variable star ranging from magnitudes 9.7 to 13.9. Blue-white, it is of spectral type B5IIIpe. A very young star, it is still accumulating interstellar material. It is obscured by, and illuminates, the surrounding nebula, NGC 6729, which brightens and darkens with it. The nebula is often compared to a comet for its appearance in a telescope, as its length is five times its width. Other stars of the cluster include S Coronae Australis, a G-class dwarf and T Tauri star.",
"title": "Features"
},
{
"paragraph_id": 10,
"text": "Nearby north, another young variable star, TY Coronae Australis, illuminates another nebula: reflection nebula NGC 6726/NGC 6727. TY Coronae Australis ranges irregularly between magnitudes 8.7 and 12.4, and the brightness of the nebula varies with it. Blue-white, it is of spectral type B8e. The largest young stars in the region, R, S, T, TY and VV Coronae Australis, are all ejecting jets of material which cause surrounding dust and gas to coalesce and form Herbig–Haro objects, many of which have been identified nearby.",
"title": "Features"
},
{
"paragraph_id": 11,
"text": "Not part of it is the globular cluster known as NGC 6723, which can be seen adjacent to the nebulosity in the neighbouring constellation of Sagittarius, but is much much further away.",
"title": "Features"
},
{
"paragraph_id": 12,
"text": "IC 1297 is a planetary nebula of apparent magnitude 10.7, which appears as a green-hued roundish object in higher-powered amateur instruments. The nebula surrounds the variable star RU Coronae Australis, which has an average apparent magnitude of 12.9 and is a WC class Wolf–Rayet star. IC 1297 is small, at only 7 arcseconds in diameter; it has been described as \"a square with rounded edges\" in the eyepiece, elongated in the north–south direction. Descriptions of its color encompass blue, blue-tinged green, and green-tinged blue.",
"title": "Features"
},
{
"paragraph_id": 13,
"text": "Corona Australis' location near the Milky Way means that galaxies are uncommonly seen. NGC 6768 is a magnitude 11.2 object 35′ south of IC 1297. It is made up of two galaxies merging, one of which is an elongated elliptical galaxy of classification E4 and the other a lenticular galaxy of classification S0. IC 4808 is a galaxy of apparent magnitude 12.9 located on the border of Corona Australis with the neighbouring constellation of Telescopium and 3.9 degrees west-southwest of Beta Sagittarii. However, amateur telescopes will only show a suggestion of its spiral structure. It is 1.9 arcminutes by 0.8 arcminutes. The central area of the galaxy does appear brighter in an amateur instrument, which shows it to be tilted northeast–southwest.",
"title": "Features"
},
{
"paragraph_id": 14,
"text": "Southeast of Theta and southwest of Eta lies the open cluster ESO 281-SC24, which is composed of the yellow 9th magnitude star GSC 7914 178 1 and five 10th to 11th magnitude stars. Halfway between Theta Coronae Australis and Theta Scorpii is the dense globular cluster NGC 6541. Described as between magnitude 6.3 and magnitude 6.6, it is visible in binoculars and small telescopes. Around 22000 light years away, it is around 100 light years in diameter. It is estimated to be around 14 billion years old. NGC 6541 appears 13.1 arcminutes in diameter and is somewhat resolvable in large amateur instruments; a 12-inch telescope reveals approximately 100 stars but the core remains unresolved.",
"title": "Features"
},
{
"paragraph_id": 15,
"text": "The Corona Australids are a meteor shower that takes place between 14 and 18 March each year, peaking around 16 March. This meteor shower does not have a high peak hourly rate. In 1953 and 1956, observers noted a maximum of 6 meteors per hour and 4 meteors per hour respectively; in 1955 the shower was \"barely resolved\". However, in 1992, astronomers detected a peak rate of 45 meteors per hour. The Corona Australids' rate varies from year to year. At only six days, the shower's duration is particularly short, and its meteoroids are small; the stream is devoid of large meteoroids. The Corona Australids were first seen with the unaided eye in 1935 and first observed with radar in 1955. Corona Australid meteors have an entry velocity of 45 kilometers per second. In 2006, a shower originating near Beta Coronae Australis was designated as the Beta Coronae Australids. They appear in May, the same month as a nearby shower known as the May Microscopids, but the two showers have different trajectories and are unlikely to be related.",
"title": "Features"
},
{
"paragraph_id": 16,
"text": "Corona Australis may have been recorded by ancient Mesopotamians in the MUL.APIN, as a constellation called MA.GUR (\"The Bark\"). However, this constellation, adjacent to SUHUR.MASH (\"The Goat-Fish\", modern Capricornus), may instead have been modern Epsilon Sagittarii. As a part of the southern sky, MA.GUR was one of the fifteen \"stars of Ea\".",
"title": "History"
},
{
"paragraph_id": 17,
"text": "In the 3rd century BC, the Greek didactic poet Aratus wrote of, but did not name the constellation, instead calling the two crowns Στεφάνοι (Stephanoi). The Greek astronomer Ptolemy described the constellation in the 2nd century AD, though with the inclusion of Alpha Telescopii, since transferred to Telescopium. Ascribing 13 stars to the constellation, he named it Στεφάνος νοτιος (Stephanos notios), \"Southern Wreath\", while other authors associated it with either Sagittarius (having fallen off his head) or Centaurus; with the former, it was called Corona Sagittarii. Similarly, the Romans called Corona Australis the \"Golden Crown of Sagittarius\". It was known as Parvum Coelum (\"Canopy\", \"Little Sky\") in the 5th century. The 18th-century French astronomer Jérôme Lalande gave it the names Sertum Australe (\"Southern Garland\") and Orbiculus Capitis, while German poet and author Philippus Caesius called it Corolla (\"Little Crown\") or Spira Australis (\"Southern Coil\"), and linked it with the Crown of Eternal Life from the New Testament. Seventeenth-century celestial cartographer Julius Schiller linked it to the Diadem of Solomon. Sometimes, Corona Australis was not the wreath of Sagittarius but arrows held in his hand.",
"title": "History"
},
{
"paragraph_id": 18,
"text": "Corona Australis has been associated with the myth of Bacchus and Stimula. Jupiter had impregnated Stimula, causing Juno to become jealous. Juno convinced Stimula to ask Jupiter to appear in his full splendor, which the mortal woman could not handle, causing her to burn. After Bacchus, Stimula's unborn child, became an adult and the god of wine, he honored his deceased mother by placing a wreath in the sky.",
"title": "History"
},
{
"paragraph_id": 19,
"text": "In Chinese astronomy, the stars of Corona Australis are located within the Black Tortoise of the North (北方玄武, Běi Fāng Xuán Wǔ). The constellation itself was known as ti'en pieh (\"Heavenly Turtle\") and during the Western Zhou period, marked the beginning of winter. However, precession over time has meant that the \"Heavenly River\" (Milky Way) became the more accurate marker to the ancient Chinese and hence supplanted the turtle in this role. Arabic names for Corona Australis include Al Ķubbah \"the Tortoise\", Al Ĥibā \"the Tent\" or Al Udḥā al Na'ām \"the Ostrich Nest\". It was later given the name Al Iklīl al Janūbiyyah, which the European authors Chilmead, Riccioli and Caesius transliterated as Alachil Elgenubi, Elkleil Elgenubi and Aladil Algenubi respectively.",
"title": "History"
},
{
"paragraph_id": 20,
"text": "The ǀXam speaking San people of South Africa knew the constellation as ≠nabbe ta !nu \"house of branches\"—owned originally by the Dassie (rock hyrax), and the star pattern depicting people sitting in a semicircle around a fire.",
"title": "History"
},
{
"paragraph_id": 21,
"text": "The indigenous Boorong people of northwestern Victoria saw it as Won, a boomerang thrown by Totyarguil (Altair). The Aranda people of Central Australia saw Corona Australis as a coolamon carrying a baby, which was accidentally dropped to earth by a group of sky-women dancing in the Milky Way. The impact of the coolamon created Gosses Bluff crater, 175 km west of Alice Springs. The Torres Strait Islanders saw Corona Australis as part of a larger constellation encompassing part of Sagittarius and the tip of Scorpius's tail; the Pleiades and Orion were also associated. This constellation was Tagai's canoe, crewed by the Pleiades, called the Usiam, and Orion, called the Seg. The myth of Tagai says that he was in charge of this canoe, but his crewmen consumed all of the supplies onboard without asking permission. Enraged, Tagai bound the Usiam with a rope and tied them to the side of the boat, then threw them overboard. Scorpius's tail represents a suckerfish, while Eta Sagittarii and Theta Coronae Australis mark the bottom of the canoe. On the island of Futuna, the figure of Corona Australis was called Tanuma and in the Tuamotus, it was called Na Kaua-ki-Tonga.",
"title": "History"
},
{
"paragraph_id": 22,
"text": "SIMBAD",
"title": "References"
},
{
"paragraph_id": 23,
"text": "",
"title": "External links"
}
] | Corona Australis is a constellation in the Southern Celestial Hemisphere. Its Latin name means "southern crown", and it is the southern counterpart of Corona Borealis, the northern crown. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. The Ancient Greeks saw Corona Australis as a wreath rather than a crown and associated it with Sagittarius or Centaurus. Other cultures have likened the pattern to a turtle, ostrich nest, a tent, or even a hut belonging to a rock hyrax. Although fainter than its northern counterpart, the oval- or horseshoe-shaped pattern of its brighter stars renders it distinctive. Alpha and Beta Coronae Australis are the two brightest stars with an apparent magnitude of around 4.1. Epsilon Coronae Australis is the brightest example of a W Ursae Majoris variable in the southern sky. Lying alongside the Milky Way, Corona Australis contains one of the closest star-forming regions to the Solar System—a dusty dark nebula known as the Corona Australis Molecular Cloud, lying about 430 light years away. Within it are stars at the earliest stages of their lifespan. The variable stars R and TY Coronae Australis light up parts of the nebula, which varies in brightness accordingly. | 2001-09-17T18:50:49Z | 2023-12-27T11:03:35Z | [
"Template:Short description",
"Template:Infobox constellation",
"Template:Cite book",
"Template:Stars of Corona Australis",
"Template:Authority control",
"Template:Sfn",
"Template:Refn",
"Template:Solar radius",
"Template:Reflist",
"Template:Constellations",
"Template:Featured article",
"Template:See also",
"Template:Transl",
"Template:Cite conference",
"Template:Cite web",
"Template:Refend",
"Template:Sky",
"Template:RA",
"Template:Solar mass",
"Template:Cite journal",
"Template:Refbegin",
"Template:Subscription required",
"Template:Commons and category",
"Template:Portal bar"
] | https://en.wikipedia.org/wiki/Corona_Australis |
6,426 | Corcovado | Corcovado (Portuguese pronunciation: [koʁkoˈvadu]) which means "hunchback" in Portuguese, is a mountain in central Rio de Janeiro, Brazil. It is a 710-metre (2,329 ft) granite peak located in the Tijuca Forest, a national park.
Corcovado hill lies just west of the city center but is wholly within the city limits and visible from great distances. It is known worldwide for the statue of Jesus atop its peak, entitled Christ the Redeemer.
The peak and statue can be accessed via a narrow road, by the 3.8 km (2.4 mi) Corcovado Rack Railway, which was opened in 1884 and refurbished in 1980, or by the walking trail on the south side of the mountain that starts from Parque Lage. The railway uses three electrically powered trains, with a capacity of 540 passengers per hour. The rail trip takes approximately 20 minutes and departs every 20 minutes. Due to its limited passenger capacity, the wait to board at the entry station can take several hours. The year-round schedule is 8:30 to 18:30.
From the train terminus and road, the observation deck at the foot of the statue is reached by 223 steps, or by elevators and escalators. Among the most popular year-round tourist attractions in Rio de Janeiro, the Corcovado railway, access roads, and statue platform are commonly crowded.
Corcovado's most popular attraction is the 38-metre (125 ft) statue depicting Jesus at its peak, entitled Christ the Redeemer (Portuguese: Cristo Redentor), and the viewing platform at its peak, drawing over 300,000 visitors per year. The statue was constructed from 1922 to 1931. From the peak's platform the panoramic view includes downtown Rio de Janeiro, Sugarloaf Mountain, the Rodrigo de Freitas lagoon, Copacabana and Ipanema beaches, Maracanã Stadium, and several of Rio de Janeiro's favelas. Cloud cover is common in Rio and the view from the platform is often obscured. Sunny days are recommended for optimal viewing.
Notable past visitors to the mountain peak include Charles Darwin, Pope Pius XII, Pope John Paul II, Alberto Santos-Dumont, Albert Einstein, Diana, Princess of Wales, and General Sherman, among others. An additional attraction of the mountain is rock climbing. The south face had 54 climbing routes in 1992. The easiest way starts from Parque Lage.
The peak of Corcovado is a big granite dome, which describes a generally vertical rocky formation. It is claimed to be the highest such formation in Brazil, the second highest being Pedra Agulha, situated near the town of Pancas in Espírito Santo.
Corcovado is considered an icon of Brazilian culture. Corcovado is a 1960 bossa nova song and jazz standard by Antônio Carlos Jobim whose lyrics draw on images of the hill. Corcovado has also been referenced in other artistic works (e.g. the lyrics of Ben Harper, literary works, films, etc.). | [
{
"paragraph_id": 0,
"text": "Corcovado (Portuguese pronunciation: [koʁkoˈvadu]) which means \"hunchback\" in Portuguese, is a mountain in central Rio de Janeiro, Brazil. It is a 710-metre (2,329 ft) granite peak located in the Tijuca Forest, a national park.",
"title": ""
},
{
"paragraph_id": 1,
"text": "Corcovado hill lies just west of the city center but is wholly within the city limits and visible from great distances. It is known worldwide for the statue of Jesus atop its peak, entitled Christ the Redeemer.",
"title": ""
},
{
"paragraph_id": 2,
"text": "The peak and statue can be accessed via a narrow road, by the 3.8 km (2.4 mi) Corcovado Rack Railway, which was opened in 1884 and refurbished in 1980, or by the walking trail on the south side of the mountain that starts from Parque Lage. The railway uses three electrically powered trains, with a capacity of 540 passengers per hour. The rail trip takes approximately 20 minutes and departs every 20 minutes. Due to its limited passenger capacity, the wait to board at the entry station can take several hours. The year-round schedule is 8:30 to 18:30.",
"title": "Access"
},
{
"paragraph_id": 3,
"text": "From the train terminus and road, the observation deck at the foot of the statue is reached by 223 steps, or by elevators and escalators. Among the most popular year-round tourist attractions in Rio de Janeiro, the Corcovado railway, access roads, and statue platform are commonly crowded.",
"title": "Access"
},
{
"paragraph_id": 4,
"text": "Corcovado's most popular attraction is the 38-metre (125 ft) statue depicting Jesus at its peak, entitled Christ the Redeemer (Portuguese: Cristo Redentor), and the viewing platform at its peak, drawing over 300,000 visitors per year. The statue was constructed from 1922 to 1931. From the peak's platform the panoramic view includes downtown Rio de Janeiro, Sugarloaf Mountain, the Rodrigo de Freitas lagoon, Copacabana and Ipanema beaches, Maracanã Stadium, and several of Rio de Janeiro's favelas. Cloud cover is common in Rio and the view from the platform is often obscured. Sunny days are recommended for optimal viewing.",
"title": "Attractions"
},
{
"paragraph_id": 5,
"text": "Notable past visitors to the mountain peak include Charles Darwin, Pope Pius XII, Pope John Paul II, Alberto Santos-Dumont, Albert Einstein, Diana, Princess of Wales, and General Sherman, among others. An additional attraction of the mountain is rock climbing. The south face had 54 climbing routes in 1992. The easiest way starts from Parque Lage.",
"title": "Attractions"
},
{
"paragraph_id": 6,
"text": "The peak of Corcovado is a big granite dome, which describes a generally vertical rocky formation. It is claimed to be the highest such formation in Brazil, the second highest being Pedra Agulha, situated near the town of Pancas in Espírito Santo.",
"title": "Geology"
},
{
"paragraph_id": 7,
"text": "Corcovado is considered an icon of Brazilian culture. Corcovado is a 1960 bossa nova song and jazz standard by Antônio Carlos Jobim whose lyrics draw on images of the hill. Corcovado has also been referenced in other artistic works (e.g. the lyrics of Ben Harper, literary works, films, etc.).",
"title": "References in Brazilian culture"
}
] | Corcovado which means "hunchback" in Portuguese, is a mountain in central Rio de Janeiro, Brazil. It is a 710-metre (2,329 ft) granite peak located in the Tijuca Forest, a national park. Corcovado hill lies just west of the city center but is wholly within the city limits and visible from great distances. It is known worldwide for the statue of Jesus atop its peak, entitled Christ the Redeemer. | 2001-09-17T20:49:38Z | 2023-11-15T13:25:18Z | [
"Template:Short description",
"Template:Infobox mountain",
"Template:Lang-pt",
"Template:Cite web",
"Template:Commons category-inline",
"Template:About",
"Template:IPA-pt",
"Template:Convert",
"Template:Reflist"
] | https://en.wikipedia.org/wiki/Corcovado |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.