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ernate histories e g frank capra s it s a wonderful life and more recently the films sliding doors and the butterfly effect however in the capra film the angel shows jimmy stewart an alternate history in which he was never born the changes in his home town are serious and far reaching creating a much darker reality for his neighbors thus if one posits as capra does that changes in personal lives create a ripple effect in the larger history then such stories do qualify as a type of alternate history one could call them alternative local history or alternative interpersonal history such worlds with relatively small and sometimes almost undiscernable changes in personal lives were given the name cognate universes by jack vance in the novelette rumfuddle one nine seven three the science fiction television show sliders presented alternate histories under the science inspired guise of quantum navigating the multiverse the alternate americas in most episodes are nasty dystopias although sometimes this is not evident |
at first another such television show a south korean drama gung presents an point of divergence where the korean monarchy is restored after the independance from the japanese empire even up to the two one st century note this website is in korean the dramatic possibilities of alternate history provide a diverse genre for exploration in role playing games many games use an alternate historical background for their campaigns in particular gurps uses a setting containing multiple different alternate histories as its default campaign setting points of divergence the key change between our history and the alternate history is known as the point of divergence pod in philip k dick s the man in the high castle the pod is the attempted assassination of franklin d roosevelt in miami in one nine three three in reality this attempt failed another alternate history with a point of divergence connected to roosevelt is the backdrop to philip roth s novel the plot against america in which roosevelt is defeated in the one ni |
ne four zero us presidential election by the isolationist charles lindbergh who reaches an accommodation with the axis powers in world war ii and keeps the united states out of the war in robert harris s fatherland the pod occurs when a german attack into the caucasus succeeds in the nazis seizing vital oil and cutting off supplies to the red army this forces the ussr to surrender enabling the axis powers to bring the remaining allies to the peace table one by one some variants of the theory of the multiverse posit that pods occur every instant springing off parallel universes for each instance even mainstream science fiction stories are known to have points of divergence the star trek franchise for example diverts from ours in that several key space disasters never occurred resulting in a much faster and smoother development of rocketry than in our timeline counterfactual and virtual history see main articles historical revisionism virtual history historians also speculate in this manner this type of specula |
tion is known commonly as counterfactual history or virtual history there is considerable debate within the community of historians about the validity and purpose of this type of speculation for alternate histories which some assert to be factual rather than speculative see conspiracy theory and historical revisionism sidewise award for alternate history in one nine nine five the sidewise award for alternate history was established to recognize best long form novels and series and best short form stories within the genres the award is named for murray leinster s story sidewise in time published alternate histories literally thousands of alternate history stories and novels have been published following is a somewhat random sampling weapons of choice axis of time series by john birmingham which is part alternate history part science fiction its point of divergence is one nine four two when an american led un multinational force arrives uptime from two zero two one via a wormhole that was accidentally generated |
as a byproduct of a scientific experiment of course one could say there is also a downtime point of divergence the point at which the un force disappears from its normal time in other words within the framing logic of parallel universe science fiction the fictional experiment creates two new worlds or histories while presumably leaving unchanged the future of a third world the one in which the wormhole was never generated lighter than a feather one nine seven one by david westheimer a story of the american invasion of japan operation olympic which was to have taken place in november one nine four five the novel is seen from the point of view of both low level japanese military and civilian and american military members pastwatch the redemption of christopher columbus by orson scott card in which scientists from the future travel back to the one five th century to prevent the european colonisation of the americas alvin maker by orson scott card in which card imagines north america where people wield magic or |
knacks and the revolution was only partly successful bring the jubilee by ward moore in which the south was not defeated in the american civil war because it won the battle of gettysburg the man in the high castle by philip k dick set in a world where the axis powers won world war ii fatherland by robert harris is also set in the one nine six zero s in a germany which won world war ii in the forfeited birthright of the abortive far western christian civilization arnold j toynbee describes a world in which the franks lost to the muslims at the battle of tours in seven three two ss gb by len deighton is a detective novel set in one nine four one britain in which the germans have successfully occupied the country if hitler had invaded england by c s forester found in his collection of published short stories gold from crete the story is a fictionalized account of a german invasion of britain in one nine four zero based on what forester saw as realistic projections of german and british capabilities the german in |
vasion fails short of reaching london due to continued british supremacy at sea and in the air the resulting lack of river transport capability leads to an allied victory pavane by keith roberts assumes that queen elizabeth i of england was assassinated and in the ensuing disorder the spanish armada was successful in suppressing protestantism the novel actually a series of shorter pieces is set in a two zero th century where technology has advanced less than in our world and where the inquisition still has power the last article is a short story by harry turtledove in which mohandas gandhi attempts to use non violent resistance against india s nazi occupiers the alteration by kingsley amis is set in a world very similar to that of pavane in this world martin luther rather than beginning the protestant reformation became pope the novel concerns the attempt to prevent a young boy with a perfect singing voice from being recruited to the vatican s eunuch choir there are a number of in jokes where famous works of |
fantasy and science fiction appear under slightly different titles the wind in the cloisters and the lord of the chalices for example the lord darcy fantasy series by randall garrett a number of short stories and one novel too many magicians based on the premise that king richard i of england returned safely from france and that roger bacon had systematised the laws of magic the stories are a series of traditional detective fiction style murder mysteries with forensic magic being used in the investigation the western lights science fantasy series by jeffrey barlough posits a cataclysmic event that has sundered western europe from the rest of the world the series features somewhat steampunk victorian technology and society juxtaposed with ice age era creatures such as mastodon and saber toothed tigers titles include dark sleeper the house in the high wood and strange cargo gurps alternate earths isbn one five five six three four three one eight three and gurps alternate earths ii isbn one five five six three f |
our three nine nine x a pair of what might have been supplements for the third edition of the gurps role playing game includes a world with a surviving confederacy a nazi japanese empire world an aztecs rule america scenario a viking empire and a unique gernsback world in which the dreams of mad scientists and doc savage have become reality the conflict between the infinity patrol and centrum across the multiplicity of parallel earths detailed in these supplements and originating in gurps time travel was made central to the fourth edition of gurps as the default setting in the basic set and in the supplement gurps infinite worlds the difference engine by william gibson and bruce sterling is a steampunk novel which deals with a victorian society in which charles babbage s analytical engine takes on the roles of modern computers a century early arrowdreams an anthology of alternate canadas edited by mark shainblum and john dupuis features stories by eric choi dave duncan glenn grant paula johanson nancy kilpatr |
ick laurent mcallister the late keith scott shane simmons michael skeet edo van belkom and allan weiss the collection garnered an aurora award in the best other work in english category while edo van belkom s short story hockey s night in canada captured another for best short form work in english ong s hat by ong s hat new jersey is an internet legend that deals with a group of renegade scientists from princeton that developed a means of travel to parallel universes and fled this universe to found a colony in another world how few remain by harry turtledove is set twenty years after a southern victory in the american civil war established the confederate states of america this novel is followed by the great war trilogy set in the one nine one zero s the american empire trilogy taking the timeline up through the one nine two zero s and three zero s and the settling accounts trilogy detailing an alternate world war ii the two georges by harry turtledove and actor richard dreyfuss is set in modern times under t |
he assumption that king george iii of great britain and george washington reached a settlement where the one three colonies remained within the british empire with increased autonomy and virtually all of their grievances redressed the book follows two royal american mounted police officers attempting to recover the famous painting of the meeting between the two georges by thomas gainsborough after it had been stolen by anti british terrorists the painting had become a national treasure and the principal symbol of the unification between britain and america making history one nine nine six by british actor comedian and novelist stephen fry is set in a parallel world in which adolf hitler was never conceived let alone born for want of a nail one nine seven three by american business historian robert n sobel details a world in which the american revolution failed the british colonies become the confederation of north america cna while the defeated rebels go into exile in spanish tejas eventually founding the uni |
ted states of mexico usm a bitter rival to the cna the gigantic multinational corporation kramer associates originally from mexico but later based in taiwan is the third world power and the first power to detonate an atomic bomb this book is of particular interest because it is written in the format of a standard popular history complete with footnotes and discussions of differing historical interpretations and for the fact that for many years at least one major municipal library the denver public library had this book filed in its history collection rather than as fiction the domination by s m stirling after the united states conquers canada in the war of one eight one two the loyalists move to south africa where they join with the boers to set up a slavery based empire called the domination of the draka the story tells of the struggle between the domination and the free world as the draka come to dominate the world they create a superhuman race conquistador by s m stirling an interdimensional gateway is dis |
covered in california which gives access to an alternate earth in which the empire of alexander the great flourished and where europeans never discovered america wild cards edited by george r r martin a series of collaborations based on the premise that an alien race released a virus just after the wwii that gave some people superpowers and others terrible deformities one six three two by eric flint found online at the baen books free library in various ebook formats its sequels starting with one six three three are available for sale a series based on the premise that an entire modern west virginia town is transported in time and space to germany during the thirty years war rivers of war by eric flint is an alternate history of the american frontier it posits that sam houston was not injured at the beginning of the war of one eight one two and substantially revises the history of the trail of tears one nine four five by newt gingrich and william r forstchen assumes that the germans perfected long range jet a |
ircraft by the end of world war ii and conducted successful raids in north america against the us nuclear program the probability broach by l neil smith one single word in the declaration of independence differs and the us becomes the north american confederation a libertarian society in the present some scientist will invent the probability broach and make contact with other universes the venus belt their majesties bucketeers the nagasaki vector tom paine maru the gallatin divergence the indians won isbn zero eight four three nine one zero one two seven by martin cruz smith imagines that the native americans had won the indian wars and kept their land the coming of the demons by gwenyth hood imagines if the execution of conradin hohenstaufen in naples on october two nine one two six eight was averted by the arrival of the pelezitereans exiled alien wanderers from another galaxy seeking an uninhabited planet on which to reestablish their advanced culture one nine zero one by robert conroy depicts a hypothetic |
al war between germany and the united states at the start of william mckinley s second term as president mamoru oshii s manga kerebos a k a hellhounds panzer cops in the united states and the film jin roh the wolf brigade both of which take place in a one nine six zero s japan that was defeated and occupied by the germans kim stanley robinson s the years of rice and salt imagines a world in which the black death of the one four th century kills nine nine of the people in europe over the next seven centuries china and the islamic world come to dominate the planet as they colonize a north america whose native peoples have all united in the hodenosaunee league under the iroquois clash in india a place of many scientific innovations and the muslims resettle a depopulated europe robert silverberg s roma eterna is set in a world where the red sea did not part before moses as a result the roman empire grew and prospered without the influence of christianity the novel is a series of short stories set in the same alte |
rnate history up to two seven five three auc terry pratchett s strata is set in a world where remus won the right to name the city and not romulus as a result the roman empire is known as the remen empire other changes result from this john m ford s the dragon waiting is set in a europe where the emperor julian lived long enough to re establish paganism in the roman empire the shadow of the lion and this rough magic a collaboration between mercedes lackey eric flint and dave freer is set in a renaissance europe where the library of alexandria was not destroyed by a christian mob and the now sainted hypatia of alexandria and john chrysostom shaped religious thought significantly altering how the church developed the novels center around the republic of venice the belisarius series of novels by david drake and eric flint take place when opposing factions from the future influence early times through intermediaries for their own purposes the good side operating through the byzantine general belisarius and the ev |
il side operating through the indian state of malwa michael moorcock s the nomad of the time streams trilogy aka the nomad of time a series of novels featuring a grown up version of e nesbit s oswald bastable from the treasure seekers and other books who experiences a variety of alternate realities that have diverged from his own time line the war lord of the air the land leviathan the steel tsar online alternate histories soc history what if is a usenet newsgroup devoted to discussing alternate histories this newsgroup has spawned a number of interesting alternate timelines including an online role playing game which has run continuously since two zero zero zero called shwi isot with a pod in one eight zero zero and in which the characters are based on the players being sent from the two one st century back to an alternate early one nine th century where they have started altering history the concept was inspired by s m stirling s island on the sea of time books in online alternate history the timeline is us |
ually referred to by the abbreviation atl alternate time line as contrasted with otl our time line which refers to real history one nine three three an alternative view of the two zero th century post one nine three three in which adolf hitler succeeds in creating an alliance between nazi germany and the british empire resulting in the invasion and conquests of france and the soviet union and the resulting long and prolonged cold war between the anglo german alliance and the united states for all time president chester a arthur or mike davis is a dystopian post wwii scenario resulting from the death of roosevelt shortly after the attack on pearl harbor featuring horrific three way race riots in the united states between white black and jewish gangs and frequent usage of nuclear weapons around the world shattered world bobby hardenbrook is a devastating alternate world war ii resulting from a soviet invasion of poland in one nine three seven the timeline currently continues up to the autumn of one nine four ei |
ght some terminology is clearly inspired by the domination as there is an alliance for democracy which however does not include the united states and a eurasian war which is an axis soviet war which precedes the main world war ii a loose bandage beck reilly is an alternate two zero th century following the failed assassination of william mckinley sealion fails steven rogers is an alternate world war ii in which germany invades england but the invasion is defeated a shot heard around the world ed thomas follows from the assassination of the prince of wales in one nine zero zero who in otl became king edward vii preventing the entente cordiale without britain as an ally france and russia are easily defeated by the central powers after the war charles de gaulle seizes power in france and plans a war of vengeance against the germans dai nippon teikoku an alternate history is a history of a japan which loses its territories on the asian mainland in a war with the soviet union as a result japan never goes to war wi |
th the united states and thus retains karafuto and micronesia decades of darkness kaiser wilhelm iii suggests the early death of president thomas jefferson leading to the secession of new england resulting in a united states of america dominated by slave owners for all nails is an ongoing collaborative online continuation of for want of a nail which ended in one nine seven one the year the book had been written the authors believed the world depicted at the end of for want of a nail was an unpleasant one hence the name inspired by chet s for all time puritan world tony jones a different english civil war results in a much earlier and much nastier american revolution britain never becomes a world power by one nine nine six the new commonwealth a totalitarian puritan theocracy controlling all of north america britain australia and most of japan has recently begun a world war against the combined european powers of the octuple alliance ill bethisad is an ongoing collaborative project with currently ca four five |
participants originally created by andrew smith from new zealand mr hughes goes to war an alternate history where charles evans hughes is elected president of the united states in one nine one six wikidusk is an open source novel wiki editable where on december two seven two zero zero four a huge explosion halfway across the galaxy had packed even more power eric flint s rare policy of supporting fanfiction based on his one six three two novel universe has created a vibrant forum section at baen s bar discussing the consequences of an event in which the fictional modern american town is transported back in time into the middle of the thirty years war in the german province of thuringia further reading chapman edgar l and carl b yoke eds classic and iconoclastic alternate history science fiction mellen two zero zero three collins william joseph paths not taken the development structure and aesthetics of the alternative history university of california at davis one nine nine zero gevers nicholas mirrors of the |
past versions of history in science fiction and fantasy university of cape town one nine nine seven hellekson karen the alternate history refiguring historical time kent state university press two zero zero one mcknight edgar vernon jr alternative history the development of a literary genre university of north carolina at chapel hill one nine nine four snider adam thinking sidewise tips for building an alternate history collection school library journal april two zero zero four see also parallel universe fiction virtual history invasion literature time travel in fiction external links soc history what if is the usenet newsgroup on alternate history shwi isot is an online rpg set in an alternate early one nine th century where people from the early two one st century have been sent back and are altering history wikisot is the wiki record of history and events for the shwi isot online rpg uchronia has a good introduction to the topic and lists over two zero zero zero works of alternate history alternate history |
discussion is a moderated forum devoted to discussing alternate history the sidewise award for alternate history lists all the winners and nominees for the award since its inception and provides information for recommending works for consideration today in alternate history a daily updated blog featuring important events in history that never occurred today in several recurring timelines this day in alternate history not to be confused with the above histalt com is author richard j rick sutcliffe s collection of alternate history links how to change the world on alternative histories mailing list about alternate history the alternate history wiki john reilly s alternative history changing the times is an alternate history electronic magazine written and maintained by alternate historians giampietro stocco s thinking counterfactual an italian uchronic novelist s english homepage science fiction themes alternate history science fiction genres audiogalaxy satellite zero six zero nine audiogalaxy was a file shar |
ing system located at http www audiogalaxy com that indexed mp three files founded by michael merhej and sporting a web based search engine always on searching for requested files auto resume and low system impact it quickly gained ground among file sharers abandoning napster in two zero zero one some observing the previous downfall of napster via lawsuit were shocked at the design of audiogalaxy which was in some ways more centralized than napster i don t get it why do you guys still come here lol famous quote by michael merhej who posted on the gd board in may of two zero zero one audiogalaxy implemented groups which allowed group members to send songs to everyone in the group clever hackers used this backdoor to circumvent the blocked songs restriction where audiogalaxy could deny transfer of specific copyrighted songs for those curious here is how blocked songs could be downloaded not quite hacking but a clever workaround you need two accounts so sign up for a second if you only have one create a group wi |
th your one st a c and get your two nd a c to join it go into your two nd a c on may nine two zero zero two audiogalaxy required songs to be in the sender s shared folder to be sent previously one could send any song to anyone by editing the cgi parameters this protection was quickly defeated by creating a dummy file in one s shared folder and sending a song with the same name due to audiogalaxy s checksum hashing the correct file was always sent despite the dummy even though audiogalaxy claimed that they were trying to cooperate with the music industry and block copyrighted songs from their network they continued to offer illegal mp three s and were sued by riaa on may two four two zero zero two on this day audiogalaxy blocked sending of all blocked songs on june one seven two zero zero two audiogalaxy reached an out of court settlement with the riaa the settlement reached would allow audiogalaxy to operate a filter in system which required that for any music available the songwriter music publisher and or r |
ecording company must first consent to the use and sharing of the work on september eight two zero zero two audiogalaxy licensed and re branded a for pay streaming service called rhapsody from listen com and discontinued its famous web based p two p service on december two five two zero zero two martin rieder wrote a preliminary form of a database backed backwards compatible audiogalaxy server dubbed openag server audiogalaxy s stated mission was to facilitate sharing of music though much more appears to have grown from its legacy it was notable for its strong community due to such features as chat enabled groups and per artist internet forums although music is no longer shared some message boards are still moderately active some of the more active forums include the radiohead rush and general discussion boards files of any type could easily be shared via audiogalaxy by renaming a file in a certain way for example cdrwin three seven zip would be shared by renaming it to cdrwin three seven zip mp three in augu |
st two zero zero five an imitation audiogalaxy site was set up for discussion boards http www agelesscommunity com external links riaa nmpa reach settlement with audiogalaxy com audiogalaxy s rhapsody service r i p audiogalaxy kennon ballou s story of audiogalaxy an audiogalaxy programmer now on web archive org file sharing networks file sharing programs virtual communities electron atomic and molecular orbitals atomic orbitals are the quantum states of the individual electrons in the electron cloud around a single atom classically the atomic orbitals can be thought of as similar to the orbits of the planets around the sun however it is important to note that the atomic orbitals cannot actually be described classically in fact explaining the behaviour of the electrons that orbit an atom was one of the driving forces behind quantum mechanics in quantum mechanics the atomic orbitals are the quantum states that electrons surrounding an atom may exist in these can be described as a wave function over space as sho |
wn in the diagram on the right by the n l and m quantum numbers of the orbital or by the names of the orbitals as used in electron configurations historical background see the article atomic orbital model for details on how the current model of atomic orbitals was developed this article also gives a less technical description of the model formal quantum mechanical definition in quantum mechanics the state of an atom i e the eigenstates of the atomic hamiltonian are expanded see configuration interaction expansion and basis linear algebra into linear combinations of anti symmetrized products slater determinants of one electron functions the spatial components of these one electron functions are called atomic orbitals when one considers also their spin component one speaks of atomic spin orbitals in atomic physics the atomic spectral lines correspond to transitions quantum leaps between quantum states of an atom these states are labelled by a set of quantum numbers summarized in the term symbol and usually asso |
ciated to particular electron configurations i e by occupations schemes of atomic orbitals e g one s two two s two two p six for the ground state of neon term symbol one s zero this notation means that the corresponding slater determinants have a clear higher weight in the configuration interaction expansion the atomic orbital concept is therefore a key concept for visualizing the excitation process associated to a given transition one can say for example for a given transition that it corresponds to the excitation of an electron from an occupied orbital to a given unoccupied orbital nevertheless one has to keep in mind that electrons are fermions ruled by pauli exclusion principle and cannot be distinguished from the other electrons in the atom moreover it sometimes happens that the configuration interaction expansion converges very slowly and that one cannot speak about simple one determinantal wave function at all this is the case when electron correlation is large hydrogen like atoms the simplest atomic o |
rbitals are those that occur in an atom with a single electron such as the hydrogen atom in this case the atomic orbitals are the eigenstates of the hydrogen hamiltonian they can be obtained analytically see hydrogen atom an atom of any other element ionized down to a single electron is very similar to hydrogen and the orbitals take the same form for atoms with two or more electrons the governing equations can only be solved with the use of methods of iterative approximation orbitals of multi electron atoms are qualitatively similar to those of hydrogen and in the simplest models they are taken to have the same form for more rigorous and precise analysis the numerical approximations must be used a given hydrogen like atomic orbital is identified by unique values of three quantum numbers n l and ml the rules restricting the values of the quantum numbers and their energies see below explain the electron configuration of the atoms and the periodic table the stationary states quantum states of the hydrogen like a |
toms are its atomic orbital however in general an electron s behavior is not fully described by a single orbital electron states are best represented by time depending mixtures linear combinations of multiple orbitals see linear combination of atomic orbitals molecular orbital method the quantum number n first appeared in the bohr model it determines among other things the distance of the electron from the nucleus all electrons with the same value of n lay at the same distance modern quantum mechanics confirms that these orbitals are closely related for this reason orbitals with the same value of n are said to comprise an shell orbitals with the same value of n and also the same value of l are even more closely related and are said to comprise a subshell qualitative characterization limitations on the quantum numbers an atomic orbital is uniquely identified by the values of the three quantum numbers and each set of the three quantum numbers corresponds to exactly one orbital but the quantum numbers only occur |
in certain combinations of values the rules governing the possible values of the quantum numbers are as follows the principal quantum number n is always a positive integer in fact it can be any positive integer but for reasons discussed below large numbers are seldom encountered each atom has in general many orbitals associated with each value of n these orbitals together are sometimes called a shell the azimuthal quantum number ell is a non negative integer within a shell where n is some integer n zero ell ranges across all integer values satisfying the relation zero le ell le n zero one for instance the n one shell has only orbitals with ell zero and the n two shell has only orbitals with ell zero and ell one the set of orbitals associated with a particular value of ell are sometimes collectively called a subshell the magnetic quantum number m ell is also always an integer within a subshell where ell is some integer ell zero m ell ranges thus ell zero le m ell le ell zero the above results may be summarize |
d in the following table each cell represents a subshell and lists the values of m ell available in that subshell empty cells represent subshells that do not exist subshells are usually identified by their n and ell values n is represented by its numerical value but ell is represented by a letter as follows zero is represented by s one by p two by d three by f and four by g for instance one may speak of the subshell with n two and ell zero as a two s subshell the shapes of orbitals any discussion of the shapes of electron orbitals is necessarily imprecise because a given electron regardless of which orbital it occupies can at any moment be found at any distance from the nucleus and in any direction due to the uncertainty principle however the electron is much more likely to be found in certain regions of the atom than in others given this a boundary surface can be drawn so that the electron has a high probability to be found anywhere within the surface and all regions outside the surface have low values the p |
recise placement of the surface is arbitrary but any reasonably compact determination must follow a pattern specified by the behavior of psi two the square of the wavefunction this boundary surface is what is meant when the shape of an orbital is mentioned generally speaking the number n determines the size and energy of the orbital as n increases the size of the orbital increases also in general terms ell determines an orbital s shape and m ell its orientation however since some orbitals are described by equations in complex numbers the shape sometimes depends on m ell also s orbitals ell zero are shaped like spheres p orbitals have the form of two ellipsoids with a point of tangency at the nucleus sometimes referred to as a dumbbell the three p orbitals in each shell are oriented at right angles to each other as determined by their respective values of m ell four of the five d orbitals look similar each with four pear shaped balls each ball tangent to two others and the centers of all four lying in one plan |
e between a pair of axes three of these planes are the xy xz and yz planes and the fourth has the centres on the x and y axes the fifth and final d orbital consists of three regions of high probability density a torus with two pear shaped regions placed symmetrically on its z axis orbital energy in atoms with a single electron essentially the hydrogen atom the energy of an orbital and consequently of any electrons in the orbital is determined exclusively by n the n one orbital has the lowest possible energy in the atom each successively higher value of n has a higher level of energy but the difference decreases as n increases for high n the level of energy becomes so high that the electron can easily escape from the atom in atoms with multiple electrons the energy of an electron depends not only on the intrinsic properties of its orbital but also on its interactions with the other electrons these interactions depend on the detail of its spatial probability distribution and so the energy levels of orbitals dep |
end not only on n but also on ell higher values of ell are associated with higher values of energy for instance the two p state is higher than the two s state when ell three the increase in energy of the orbital becomes so large as to push the energy of orbital above the energy of the s orbital in the next higher shell when ell four the energy is pushed into the shell two steps higher the energy order of the first two four subshells is given in the following table each cell represents a subshell with n and ell given by its row and column indices respectively the number in the cell is the subshell s position in the sequence empty cells represent subshells that either do not exist or stand farther down in the sequence electron placement and the periodic table several rules govern the placement of electrons in orbitals electron configuration the first dictates that no two electrons in an atom may have the same set of values of quantum numbers this is the pauli exclusion principle these quantum numbers include th |
e three that define orbitals as well as the hitherto unmentioned s thus two electrons may occupy a single orbital so long as they have different values of s however only two electrons because of their spin can be associated with each orbital additionally an electron always tries to occupy the lowest possible energy state it is possible for it to occupy any orbital so long as it does not violate the pauli exclusion principle but if lower energy orbitals are available this condition is unstable the electron will eventually lose energy by releasing a photon and drop into the lower orbital thus electrons fill orbitals in the order specified by the energy sequence given above this behavior is responsible for the structure of the periodic table the table may be divided into several rows called periods numbered starting with one at the top the presently known elements occupy seven periods if a certain period has number i it consists of elements whose outermost electrons fall in the ith shell the periodic table may a |
lso be divided into several numbered rectangular blocks the elements belonging to a given block have this common feature their highest energy electrons all belong to the same ell state but the n associated with that ell state depends upon the period for instance the leftmost two columns constitute the s block the outermost electrons of li and be respectively belong to the two s subshell and those of na and mg to the three s subshell the number of electrons in a neutral atom increases with the atomic number the electrons in the outermost shell or valence electrons tend to be responsible for an element s chemical behavior elements that contain the same number of valence electrons can be grouped together and display similar chemical properties see also list of hund s rules electron configuration atomic electron configuration table molecular orbital energy level external links covalent bonds and molecular structure the orbitron a visualization of all common and uncommon atomic orbitals from one s to seven g david |
manthey s orbital viewer renders orbitals with n three zero java orbital viewer applet references tipler paul ralph llewellyn two zero zero three modern physics four th ed new york w h freeman and company isbn zero seven one six seven four three four five zero chemical bonding atomic physics in chemistry an amino acid is any molecule that contains both amino and carboxylic acid functional groups in biochemistry this shorter and more general term is frequently used to refer to alpha amino acids those amino acids in which the amino and carboxylate functionalities are attached to the same carbon the so called carbon an amino acid residue is what is left of an amino acid once a molecule of water has been lost an h from the nitrogenous side and an oh from the carboxylic side in the formation of a peptide bond overview amino acids are the basic structural building units of proteins they form short polymer chains called peptides or polypeptides which in turn form structures called proteins the process of such forma |
tion is known as translation which is part of protein synthesis phenylalanine is one of the standard amino acids twenty amino acids are encoded by the standard genetic code and are called proteinogenic or standard amino acids at least two others are also coded by dna in a non standard manner as follows selenocysteine is incorporated into some proteins at a uga codon which is normally a stop codon pyrrolysine is used by some methanogens in enzymes that they use to produce methane it is coded for similarly to selenocysteine but with the codon uag instead other amino acids contained in proteins are usually formed by post translational modification which is modification after translation in protein synthesis these modifications are often essential for the function of the protein proline is the only proteinogenic amino acid whose side group is cyclic and links to the a amino group forming a secondary amino group formerly proline was misleadingly called an imino acid over one hundred amino acids have been found in |
nature some of these have been detected in meteorites especially in a type known as carbonaceous chondrites microorganisms and plants often produce very uncommon amino acids which can be found in peptidic antibiotics e g nisin or alamethicin lanthionine is a sulfide bridged alanine dimer which is found together with unsaturated amino acids in lantibiotics antibiotic peptides of microbial origin one aminocyclopropane one carboxylic acid acc is a small disubstituted cyclic amino acid and a key intermediate in the production of the plant hormone ethylene in addition to protein synthesis amino acids have other biologically important roles glycine and glutamate are neurotransmitters as well as standard amino acids in proteins many amino acids are used to synthesize other molecules for example tryptophan is a precursor of the neurotransmitter serotonin glycine is one of the reactants in the synthesis of porphyrins such as heme numerous non standard amino acids are also biologically important gamma aminobutyric acid |
is another neurotransmitter carnitine is used in lipid transport within a cell ornithine citrulline homocysteine hydroxyproline hydroxylysine and sarcosine some of the two zero standard amino acids are called essential amino acids because they cannot be synthesized by the body from other compounds through chemical reactions but instead must be taken in with food in humans the essential amino acids are lysine leucine isoleucine methionine phenylalanine threonine tryptophan valine histidine and arginine are generally considered essential only in children because of their inability to synthesise them given their undeveloped metabolisms the phrase branched chain amino acids is sometimes used to refer to the aliphatic amino acids leucine isoleucine and valine general structure the general structure of proteinogenic alpha amino acids is r h two n c cooh h where r represents a side chain specific to each amino acid amino acids are usually classified by the properties of the side chain into four groups the side chai |
n can make them behave like a weak acid a weak base a hydrophile if they are polar and hydrophobe if they are nonpolar isomerism except for glycine where r h amino acids occur in two possible optical isomers called d and l using the newer cahn ingold prelog priority rules for designating the configuration of optical isomers the l isomer would assigned the letter s and the d isomer would be assigned the letter r the l or s amino acids represent the vast majority of amino acids found in proteins d or r amino acids are found in some proteins produced by exotic sea dwelling organisms such as cone snails they are also abundant components of the cell walls of bacteria the l and d conventions for amino acid do not refer to their own optical activity but rather to the optical activity of glyceraldehyde as an analogue of the amino acids s glyceraldehyde is levorotary and r glyceraldehyde is dexterorotary and so s amino acids are called l even if they are not levorotary and r amino acids are likewise called d even if t |
hey are not dexterorotary reactions proteins are created by polymerization of amino acids by peptide bonds in a process called translation this condensation reaction yields the newly formed peptide bond and a molecule of water peptide bond formation peptide bond formation one amino acid two zwitterion structure three two amino acids forming a peptide bond see also bond list of standard amino acids structures structures and symbols of the two zero amino acids present in genetic code image l alanine png alanine ala a image l arginine png arginine arg r image l asparagine png asparagine asn n image l aspartic acid png aspartic acid asp d image l cysteine png cysteine cys c image l glutamic acid png glutamic acid glu e image l glutamine png glutamine gln q image glycine two png glycine gly g image l histidine png histidine his h image l isoleucine png isoleucine ile i image l leucine png leucine leu l image l lysine png lysine lys k image l methionine png methionine met m image l phenylalanine png phenylalanine p |
he f image l proline png proline pro p image l serine png serine ser s image l threonine png threonine thr t image l tryptophan png tryptophan trp w image l tyrosine png tyrosine tyr y image l valine png valine val v chemical properties following is a table listing the one letter symbols the three letter symbols and the chemical properties of the side chains of the standard amino acids the mass listed is the weighted average of all common isotopes and includes the mass of h two o the one letter symbol for an undetermined amino acid is x the three letter symbol asx or one letter symbol b means the amino acid is either asparagine or aspartic acid whereas glx or z means either glutamic acid or glutamine the three letter symbol sec or one letter symbol u refers to selenocysteine the letters j and o are not used hydrophilic and hydrophobic amino acids depending on how polar the side chain aminoacids can be hydrophilic or hydrophobic to various degree this influences their interaction with other structures both wit |
hin the protein itself and within other proteins the distribution of hydrophilic and hydrophobic aminoacids determines the tertiary structure of the protein and their physical location on the outside structure of the proteins influences their quaternary structure for example soluble proteins have surfaces rich with polar aminoacids like serine and threonine while integral membrane proteins tend to have outer ring of hydrophobic aminoacids that anchors them to the lipid bilayer and proteins anchored to the membrane have a hydrophobic end that locks into the membrane similarly proteins that have to bind to positive charged molecules have surfaces rich with negatively charged aminoacids like glutamate and aspartate while proteins binding to negative charged molecules have surfaces rich with positively charged chains like lysine and arginine hydrophilic and hydrophobic interactions of the proteins do not have to rely only on aminoacids themselves by various posttranslational modifications other chains can be atta |
ched to the proteins forming hydrophobic lipoproteins or hydrophylic glycoproteins nonstandard amino acids aside from the twenty standard amino acids and the two special amino acids selenocysteine and pyrrolysine already mentioned above there is a vast number of nonstandard amino acids which are not used in the body s regular manufacturing of proteins examples of nonstandard amino acids include the sulfur containing taurine and the neurotransmitters gaba and dopamine other examples are lanthionine two aminoisobutyric acid dehydroalanine dehydro amino butyric acid nonstandard amino acids are usually formed through modifications to standard amino acids for example taurine can be formed by the decarboxylation of cysteine while dopamine is synthesized from tyrosine and hydroxyproline is made by a posttranslational modification from proline uses of substances derived from amino acids aspartame aspartyl phenylalanine one methyl ester is an artificial sweetener five htp five hydroxytryptophan has been used to treat |
neurological problems associated with pku phenylketonuria as well as depression as an alternative to l tryptophan l dopa l dihydroxyphenylalanine is a drug used to treat parkinsonism monosodium glutamate is a food additive to enhance flavor see also essential amino acids strecker amino acid synthesis references doolittle r f one nine eight nine redundancies in protein sequences in predictions of protein structure and the principles of protein conformation fasman g d ed plenum press new york pp five nine nine six two three david l nelson and michael m cox lehninger principles of biochemistry three rd edition two zero zero zero worth publishers isbn one five seven two five nine one five three six on the hydrophobic nature of cysteine external links molecular expressions the amino acid collection has detailed information and microscopy photographs of each amino acid two two nd amino acid press release from ohio state claiming discovery of a two two nd amino acid amino acids nitrogen metabolism alan turing is oft |
en considered the father of modern computer science alan mathison turing june two three one nine one two june seven one nine five four was a british mathematician logician and cryptographer turing is often considered to be a father of modern computer science with the turing test turing made a significant and characteristically provocative contribution to the debate regarding artificial intelligence whether it will ever be possible to say that a machine is conscious and can think he provided an influential formalisation of the concept of algorithm and computation with the turing machine formulating the now widely accepted turing version of the church turing thesis namely that any practical computing model has either the equivalent or a subset of the capabilities of a turing machine during world war ii turing worked at bletchley park britain s codebreaking centre and was for a time head of hut eight the section responsible for german naval cryptanalysis he devised a number of techniques for breaking german ciph |
ers including the method of the bombe an electromechanical machine which could find settings for the enigma machine after the war he worked at the national physical laboratory creating one of the first designs for a stored program computer although it was never actually built in one nine four seven he moved to the university of manchester to work largely on software on the manchester mark i then emerging as one of the world s earliest true computers in one nine five two turing was convicted of acts of gross indecency after admitting to a sexual relationship with a man in manchester he was placed on probation and required to undergo hormone therapy when alan turing died in one nine five four an inquest found that he had committed suicide by eating an apple laced with cyanide childhood and youth turing was conceived in one nine one one in chatrapur india his father julius mathison turing was a member of the indian civil service julius and wife ethel n e stoney wanted alan to be brought up in britain so they ret |
urned to paddington london his father s civil service commission was still active and during turing s childhood years his parents travelled between guildford england and india leaving their two sons to stay with friends in england rather than risk their health in the british colony very early in life turing showed signs of the genius he was to display more prominently later he is said to have taught himself to read in three weeks and to have shown an early affinity for numbers and puzzles his parents enrolled him at st michael s a day school at six years of age the headmistress recognized his genius early on as did many of his subsequent educators in one nine two six at the age of one four he went on to sherborne school in dorset his first day of term coincided with a general strike in england and so determined was he to attend his first day that he rode his bike unaccompanied over sixty miles from southampton to school stopping overnight at an inn a feat reported in the local press turing s natural inclinati |
on toward mathematics and science did not earn him respect with the teachers at sherborne a famous and expensive public school a british private school with charitable status whose definition of education placed more emphasis on the classics his headmaster wrote to his parents i hope he will not fall between two schools if he is to stay at public school he must aim at becoming educated if he is to be solely a scientific specialist he is wasting his time at a public school but despite this turing continued to show remarkable ability in the studies he loved solving advanced problems in one nine two seven without having even studied elementary calculus in one nine two eight aged sixteen turing encountered albert einstein s work not only did he grasp it but he extrapolated einstein s questioning of newton s laws of motion from a text in which this was never made explicit the computer room at king s is now named after turing who became a student there in one nine three one and a fellow in one nine three five turin |
g s hopes and ambitions at school were raised by his strong feelings for his friend christopher morcom with whom he fell in love though the feeling was not reciprocated morcom died only a few weeks into their last term at sherborne from complications of bovine tuberculosis contracted after drinking infected cow s milk as a boy turing was heart broken university and his work on computability due to his unwillingness to work as hard on his classical studies as on science and mathematics turing failed to win a scholarship to trinity college cambridge and went on to the college of his second choice king s college cambridge he was an undergraduate from one nine three one to one nine three four graduating with a distinguished degree and in one nine three five was elected a fellow at king s on the strength of a dissertation on the gaussian error function alan turing on the steps of the bus with members of the walton athletic club one nine four six in his momentous paper on computable numbers with an application to t |
he entscheidungsproblem submitted on may two eight one nine three six turing reformulated kurt g del s one nine three one results on the limits of proof and computation substituting g del s universal arithmetics based formal language by what are now called turing machines formal and simple devices he proved that such a machine would be capable of performing any conceivable mathematical problem if it were representable as an algorithm even if no actual turing machine would be likely to have practical applications being much slower than alternatives turing machines are to this day the central object of study in theory of computation he went on to prove that there was no solution to the entscheidungsproblem by first showing that the halting problem for turing machines is uncomputable it is not possible to algorithmically decide whether a given turing machine will ever halt while his proof was published subsequent to alonzo church s equivalent proof in respect to his lambda calculus turing s work is considerably |
more accessible and intuitive it was also novel in its notion of a universal turing machine the idea that such a machine could perform the tasks of any other machine the paper also introduces the notion of definable numbers most of one nine three seven and one nine three eight he spent at princeton university studying under alonzo church in one nine three eight he obtained his ph d from princeton his dissertation introduced the notion of hypercomputation where turing machines are augmented with so called oracles allowing a study of problems that cannot be solved algorithmically back in cambridge in one nine three nine he attended lectures by ludwig wittgenstein about the foundations of mathematics the two argued and disagreed vehemently with turing defending formalism and wittgenstein arguing that mathematics is overvalued and does not discover any absolute truths wittgenstein one nine three two one nine seven six cryptanalysis replica of a bombe machine during world war ii turing was a major participant in t |
he efforts at bletchley park to break german ciphers turing s codebreaking work was kept secret until the one nine seven zero s not even his close friends knew about it he contributed several mathematical insights into breaking both the enigma machine and the lorenz sz four zero four two a teletype cipher attachment codenamed tunny by the british and was for a time head of hut eight the section responsible for reading german naval signals two cottages in the stable yard at bletchley park turing worked here from one nine three nine one nine four zero until he moved to hut eight since september one nine three eight turing had been recruited to work part time for the government code and cypher school turing reported to bletchley park when war was declared in september one nine three nine to break enigma turing devised an electromechanical machine which searched for the correct settings of the enigma rotors the machine was called the bombe named after the polish designed bomba using a bombe it was possible to ign |
ore the effect of the enigma plugboard and consider the settings of its rotors alone and eliminate most of them from consideration for each possible setting a chain of logical deductions was implemented electrically and it was possible to detect when a contradiction had occurred and rule out that setting turing s bombe was first installed on one eight march one nine four zero and with an enhancement suggested by mathematician gordon welchman was the primary tool used to read enigma traffic over two zero zero bombes were in operation by the end of the war in december one nine four zero turing solved the naval enigma indicator system which was more complex than the indicator systems used by the other services turing also invented a bayesian statistical technique termed banburismus to assist in breaking naval enigma banburismus could rule out certain orders of the enigma rotors reducing time needed to test settings on the bombes against the lorenz cipher turing devised a technique termed turingismus or turingery |
although other methods were also used in the spring of one nine four one turing proposed marriage to fellow hut eight co worker joan clarke although the engagement was broken off by mutual agreement in the summer in late november one nine four two turing visited the us to work on secure speech devices and naval enigma returning in march one nine four three during his absence hugh alexander had assumed the position of head of hut eight although alexander had been de facto head for some time turing having little interest in the day to day running of the section turing became a general consultant for cryptanalysis at bletchley park in the latter part of the war teaching himself electronics at the same time turing undertook assisted by engineer donald bayley the design of a portable machine codenamed delilah to allow secure voice communications intended for different applications delilah lacked capability for use with long distance radio transmissions and was completed too late to be used in the war though turin |
g demonstrated it to officials by encrypting decrypting a recording of a winston churchill speech delilah was not adopted for use in one nine four five turing was awarded the obe for his sterling wartime services early computers and the turing test turing achieved world class marathon standards his best time of two hours four six minutes three seconds was only one one minutes slower than the winner in the one nine four eight olympic games from one nine four five to one nine four seven he was at the national physical laboratory where he worked on the design of ace automatic computing engine he presented a paper on february one nine one nine four six which was the first complete design of a stored program computer although he succeeded in designing the ace there were delays in starting the project and he became disillusioned in late one nine four seven he returned to cambridge for a sabbatical year while he was at cambridge work on building the ace stopped before it was ever begun in one nine four nine he becam |
e deputy director of the computing laboratory at the university of manchester and worked on software for one of the earliest true computers the manchester mark i during this time he continued to do more abstract work and in computing machinery and intelligence mind october one nine five zero turing addressed the problem of artificial intelligence and proposed an experiment now known as the turing test an attempt to define a standard for a machine to be called sentient in one nine four eight turing working with his former undergraduate colleague d g champernowne began writing a chess program for a computer that did not yet exist in one nine five two lacking a computer powerful enough to execute the program turing played a game in which he simulated the computer taking about half an hour per move the game was recorded the program lost to a colleague of turing alick glennie however it is said that the program won a game against champernowne s wife pattern formation and mathematical biology turing worked from one |
nine five two until his death in one nine five four on mathematical biology specifically morphogenesis he published one paper on the subject called the chemical basis of morphogenesis in one nine five two his central interest in the field was understanding fibonacci phyllotaxis the existence of fibonacci numbers in plant structures he used reaction diffusion equations which are now central to the field of pattern formation later papers went unpublished until one nine nine two when collected works of a m turing was published prosecution for homosexuality and turing s death turing was a homosexual man during a period when homosexuality was illegal in one nine five two his lover arnold murray helped an accomplice to break into turing s house and turing went to the police to report the crime as a result of the police investigation turing acknowledged a sexual relationship with murray and they were charged with gross indecency under section one one of the criminal law amendment act of one eight eight five turing |
was unrepentant and was convicted although he could have been sent to prison he was placed on probation conditional on him undergoing hormonal treatment designed to reduce libido he accepted the oestrogen hormone injections which lasted for a year with side effects including the development of breasts his conviction led to a removal of his security clearance and prevented him from continuing consultancy for gchq on cryptographic matters in one nine five four he died of cyanide poisoning apparently from a cyanide laced apple he left half eaten the apple itself was never tested for contamination with cyanide and cyanide poisoning as a cause of death was established by a post mortem most believe that his death was intentional and the death was ruled a suicide it is rumoured that this method of self poisoning was in tribute to turing s beloved film snow white and the seven dwarfs his mother however strenuously argued that the ingestion was accidental due to his careless storage of laboratory chemicals friends of |
his have said that turing may have killed himself in this ambiguous way quite deliberately to give his mother some plausible deniability the possibility of assassination has also been suggested owing to turing s involvement in the secret service and the perception of turing as a security risk due to his homosexuality in the book zeroes and ones author sadie plant speculates that the rainbow apple logo with a bite taken out of it was an homage to turing this seems to be an urban legend as the apple logo was designed in one nine seven six two years before gilbert baker s rainbow pride flag see also sodomy law recognition since one nine six six the turing award has been given by the association for computing machinery to a person for technical contributions to the computing community it is widely considered to be the equivalent of the nobel prize in the computing world in one nine nine four a stretch of the manchester city ring road was named alan turing way on two three june one nine nine eight on what would ha |
ve been turing s eight six th birthday andrew hodges his biographer unveiled an official english heritage blue plaque on his childhood home in warrington crescent london now the colonnade hotel alan turing memorial statue in sackville park a statue of turing was unveiled in manchester on june two three two zero zero one it is in sackville park between the university of manchester building on whitworth street and the canal street gay village to mark the five zero th anniversary of his death a memorial plaque was unveiled at his former residence hollymeade in wilmslow on june seven two zero zero four plaque marking turing s home the alan turing institute was initiated by umist and university of manchester in summer two zero zero four a celebration of turing s life and achievements was held at the university of manchester on five june two zero zero four it was arranged by the british logic colloquium and the british society for the history of mathematics on october two eight two zero zero four a bronze statue of |
alan turing sculpted by john w mills was unveiled at the university of surrey the statue marks the five zero th anniversary of turing s death it portrays turing carrying his books across the campus holtsoft produces a programming language named for turing the language is designed for beginner programmers and has no direct access to the hardware the polytechnic university of puerto rico named a computer laboratory for graduate studies the turing lab turing biographies andrew hodges wrote a definitive biography alan turing the enigma in one nine eight three see references below the play breaking the code by hugh whitemore is about the life and death of turing in the original west end and broadway runs the role of turing was played by derek jacobi who also played turing in a one nine nine five television adaptation of the play turing in fiction turing appears as a character in neal stephenson s cryptonomicon in another one of stephenson s books the diamond age there is an intuitive explanation of recursion impo |
rtant to turing s and related work on computability put into the format of a child s book turing police artificial intelligence law enforcers appear in william gibson s neuromancer in white wolf game studio s world of darkness role playing universe turing was a leading member of the mage faction known as the virtual adepts an fbi agent named alan turing made an appearance in the webcomic questionable content as a homage to turing appears in enigma by robert harris a young alan turing introduces the title character to g del s first incompleteness theorem in apostolos doxiadis s novel uncle petros and goldbach s conjecture in the one nine eight nine doctor who serial the curse of fenric the character of dr judson is based on turing turing himself is a narrator of the doctor who spin off novel the turing test by paul leonard greg egan s novella oracle is about an alternate universe version of turing in arthur c clarke s two zero one zero odyssey two the sequel to two zero zero one a space odyssey the stoic dr ch |
andra the programmer who created hal nine zero zero zero has a completely spartan cubicle except for a photo of turing beside his computer screen see also list of gay lesbian or bisexual people alan turing s unorganized machines references copeland b jack two zero zero four colossus its origins and originators ieee annals of the history of computing two six four three eight four five copeland b jack editor two zero zero four the essential turing oxford university press isbn zero one nine eight two five zero seven nine seven hardback and isbn zero one nine eight two five zero eight zero zero paperback copeland b jack editor two zero zero five alan turing s automatic computing engine oxford university press isbn zero one nine eight five six five nine three three hodges andrew one nine eight three two zero zero zero alan turing the enigma simon one nine nine five london science museum isbn zero nine zero one eight zero five nine four seven ludwig wittgenstein one nine three two one nine seven six wittgenstein s |
lectures on the foundations of mathematics one nine three two one nine three five edited by cora diamond cornell university press johnson george two zero zero five enigmatic new york times book review one two one eight two zero zero five review of david leavitt the man who knew too much alan turing and the invention of the computer two zero zero five holt jim two zero zero six code breaker the life and death of alan turing the new yorker one three zero two zero zero six review of david leavitt the man who knew too much alan turing and the invention of the computer two zero zero five note hodges p two six external links alan turing home page by andrew hodges including a short biography alanturing net turing archive for the history of computing by jack copeland a short biography alan turing towards a digital mind part one computing machinery and intelligence full text of article skyscraper song inspired by alan turing hollymeade unveiling of memorial plaque marking five zero th anniversary of turing s untimely |
death alan turing and morphogenesis the turing archive turing day two zero zero two turing two zero zero four a celebration of his life and achievements stanford encyclopedia of philosophy entry photos one nine one two births one nine five four deaths two zero th century mathematicians two zero th century philosophers alan turing alumni of king s college cambridge british world war ii veterans british computer scientists british cryptographers at bletchley park computer designers computer pioneers computer scientists english inventors english mathematicians fellows of the royal society formal methods people lgbt history of the united kingdom lesbian gay bisexual or transgender people suicides old shirburnians this article explains the meaning of area as a physical quantity the article area geometry is more mathematical see also area disambiguation area is a physical quantity expressing the size of a part of a surface surface area is the summation of the areas of the exposed sides of an object units units for |
measuring surface area include square metre si derived unit are one zero zero square metres hectare one zero zero zero zero square metres square kilometre one zero zero zero zero zero zero square metres square megametre one zero one two square metres imperial units as currently defined from the metre square foot plural square feet zero zero nine two nine zero three zero four square metres square yard nine square feet zero eight three six one two seven three six square metres square perch three zero two five square yards two five two nine two eight five two six square metres acre one six zero square perches or four three five six zero square feet four zero four six eight five six four two two four square metres square mile six four zero acres two five eight nine nine eight eight one one zero three square kilometres old european area units still in used in some private matters e g land sale advertisements square fathomor fahomia in some sources three five nine six seven square metres cadastral moon acre one six |
zero zero square fathoms five seven five five square metres the article orders of magnitude links to lists of objects of comparable surface area useful formulas area of a rectangle and in particular a square length width area of a triangle base height area of a disk r area of an ellipse a b area of a sphere four r d which is the first derivative of the formula for volume of a sphere area of a trapezoid if a and b are the two parallel sides and h is the distance height between the parallels the area formula is as below a frac a b h or a frac total surface area of a right circular cylinder two r h r lateral surface area of a right circular cylinder two r h total surface area of a right circular cone r l r lateral surface area of a right circular cone r l diameters isn t exactly very relevant here and statements of currents are meaningless without information on the cable type ambient temperature and installation conditions cross sectional area csa of electrical wire rough figures for the cross sectional area o |
f copper conductor csa mm diameter mm current a one zero two eight one three one five three five one seven two five four two two four four zero four eight three two six zero five four four one one zero zero six eight five five one six zero eight zero seven four two five zero nine eight nine seven area the astronomical unit au or au or a u or sometimes ua is a unit of distance approximately equal to the mean distance between earth and sun the currently accepted value of the au is one four nine five nine seven eight seven zero six nine one three zero metres about one five zero million kilometres or nine three million miles the symbol ua is recommended by the bureau international des poids et mesures but in the united states and other anglophone countries the reverse usage is more common the international astronomical union recommends au and international standard iso three one one uses au the distance earth s orbit is not a circle but an ellipse originally the au was defined as the length of the semimajor axis |
of said orbit for greater precision the international astronomical union in one nine seven six defined the au as the distance from the sun at which a particle of negligible mass in an unperturbed circular orbit would have an orbital period of three six five two five six eight nine eight three days a gaussian year more accurately it is the distance such that the heliocentric gravitational constant the product gm is equal to zero zero one seven two zero two zero nine eight nine five au d history aristarchus of samos estimated the distance to the sun to be about two zero times the distance to the moon whereas the true ratio is about three nine zero his estimate was based on the angle between the half moon and the sun which he estimated as eight seven according to eusebius of caesarea in the praeparatio evangelica eratosthenes found the distance to the sun to be literally of stadia myriads four zero zero and eight zero zero zero zero this has been translated either as four zero eight zero zero zero zero stadia on |
e nine zero three translation by e h gifford or as eight zero four zero zero zero zero zero zero stadia edition of edouard des places dated one nine seven four one nine nine one using the greek stadium of one eight five metres the former translation comes to a far too low seven five five zero zero zero km whereas the second translation comes to a very accurate one four nine million km at the time the au was introduced its actual value was very poorly known but planetary distances in terms of au could be determined from heliocentric geometry and kepler s laws of planetary motion the value of the au was first estimated by jean richer and giovanni domenico cassini in one six seven two by measuring the parallax of mars from two locations on the earth they arrived at a figure of about one four zero million kilometers a somewhat more accurate estimate can be obtained by observing the transit of venus this method was devised by edmond halley and applied to the transits of venus observed in one seven six one and one |
seven six nine and then again in one eight seven four and one eight eight two another method involved determining the constant of aberration and simon newcomb gave great weight to this method when deriving his widely accepted value of eight eight zero for the solar parallax close to the modern value of eight seven nine four one four eight the discovery of the near earth asteroid four three three eros and its passage near the earth in one nine zero zero one nine zero one allowed a considerable improvement in parallax measurement more recently very precise measurements have been carried out by radar and by telemetry from space probes while the value of the astronomical unit is now known to great precision the value of the mass of the sun is not because of uncertainty in the value of the gravitational constant because the gravitational constant is known to only five or six significant digits while the positions of the planets are known to one one or one two digits calculations in celestial mechanics are typicall |
y performed in solar masses and astronomical units rather than in kilograms and kilometres this approach makes all results dependent on the gravitational constant a conversion to si units would separate the results from the gravitational constant at the cost of introducing additional uncertainty by assigning a specific value to that unknown constant it is known that the mass of the sun is very slowly decreasing and therefore the orbital period of a body at a given distance is increasing this implies that the au is getting smaller by about one centimetre per year over time examples the distances are approximate mean distances it has to be taken into consideration that the distances between celestial bodies change in time due to their orbits and other factors the earth is one zero zero zero zero two au from the sun the moon is zero zero zero two six zero zero zero zero one au from the earth mars is one five two zero one four au from the sun jupiter is five two zero zero zero five au from the sun pluto is three |
nine five nine eight au from the sun nine zero three seven seven sedna s orbit ranges between seven six and nine four two au from the sun sedna is currently as of two zero zero six about nine zero au from the sun as of november two zero zero five voyager one the farthest human made object is nine seven au from the sun the mean diameter of the solar system including the oort cloud is approximately one zero five au proxima centauri the nearest star is two six eight zero zero zero au away from the sun the mean diameter of betelgeuse is two five seven au the distance from the sun to the centre of the milky way is approximately one seven one zero nine au some conversion factors one au one four nine five nine seven eight seven zero six nine one zero zero three zero km nine two nine five five eight zero seven miles eight three one seven light minutes four nine nine light seconds one light second zero zero zero two au one light minute zero one two zero au one light hour seven two one four au one light day one seven t |
hree au one light year six three two four one au one pc two zero six two six five au see also conversion of units light year orders of magnitude parsec references e myles standish report of the iau wgas sub group on numerical standards in highlights of astronomy i appenzeller ed dordrecht kluwer academic publishers one nine nine five complete report available online postscript tables from the report also available astrodynamic constants and parameters d d mccarthy ed iers conventions one nine nine six iers technical note two one observatoire de paris july one nine nine six external links units outside the si at the nist web site recommendations concerning units at the iau web site solar mass loss the astronomical unit and the scale of the solar system a discussion of the relation between the au and other quantities celestial mechanics astronomical units of length artist is a descriptive term applied to a person who engages in an activity deemed to be an art it is also used in a qualitative sense of a person c |
reative in innovative in or adept at an artistic practice most often the term describes those who create within a context of high culture activities such as drawing and painting sculpture acting dancing writing filmmaking and music people who use imagination and talent or skill to create works that can be judged to have an aesthetic value art historians and critics will define as artists those who produce art within a recognised or recognisable discipline the term is also used to denote highly skilled people in non arts activities as well crafts medicine alchemy mechanics mathematics defense martial arts and architecture for example the designation is applied to illegal activities like a scam artist the term artist could also refer to a con artist there is no consensus about what constitutes art or who is or is not an artist often discussions on the subject focus on the differences between artist and technician or entertainer or artisan fine art and applied art or what constitutes art and what does not in add |
ition the french word artiste which in french simply means artist has been imported into the english language in english usage it has connotations some of them derogatory which differ somewhat from the english term artist the oxford english dictionary cites broad meanings of the term artist a learned person or master of arts one who pursues a practical science traditionally medicine astrology alchemy chemistry a follower of a pursuit in which skill comes by study or practice the opposite of a theorist a follower of a manual art such as a mechanic one who makes their craft a fine art one who cultivates one of the fine arts traditionally the arts presided over by the muses referenced from in greek the word techn is often mistranslated into art in actuality techn implies mastery of a craft any craft the latin derived form of the word is tecnicus from which the english words technique technology technical are derived our word art is derived from the latin ars which though literally defined means skill method or t |
echnique holds a connotation of beauty many contemporary definitions of artist and art are highly contingent on culture resisting aesthetic prescription in much the same way that the features constituting beauty and the beautiful cannot be easily standardized without corruption into kitsch examples of art and artist actor laurence olivier architect antoni gaud ballet vaslav nijinsky calligraphy hokusai choreographer martha graham composer giuseppe fortunino francesco verdi conceptual art vanessa beecroft dancer isadora duncan entertainer pt barnum fashion designer pierre cardin figure skater michelle kwan game designer shigeru miyamoto horticulture andr le n tre illusionist houdini industrial designer pininfarina jeweller faberg movie director sergei eisenstein muralist diego rivera musician niccolo paganini novelist dostoevsky musical instrument maker stradivari orator cicero painter pablo ruiz picasso photographer robert mapplethorpe pianist glenn gould playwright harold pinter poet william shakespeare pott |
er peter voulkos singer nico sculptor michelangelo buonarotti storyteller el gahshigar artists art and design workers aesthetics actaeon and his dogs in greek mythology actaeon or aktaion son of aristaeus and autonoe in boeotia was a hunter who suffered the wrath of artemis artemis was bathing in the woods near boeotian orchomenos when the hunter actaeon stumbled across her thus seeing her naked he stopped and stared amazed at her ravishing beauty when she saw him artemis punished him by declaring that he must never speak again if he tried to speak he would be changed into a stag for his unlucky profanation of her virgin s mysteries upon hearing his hunting group calling to him he cried out to them and immediately was changed into a stag his own hounds turned upon him instantly and killed him he was torn apart the hounds were so upset with their master s death that chiron made a statue so lifelike that the hounds thought it was actaeon there are various other versions apollodorus states that his offence was t |
hat he was a rival of zeus for semele who was also his aunt while in euripedes bacchae he boasts that he is better hunter than artemis look at actaeon s wretched fate who by the man eating hounds he had raised was torn apart better at hunting than artemis he had boasted to be in the meadows diodorus siculus has it that actaeon wanted to marry artemis other authors say the hounds were artemis own actaeon in art actaeon torn by his hounds is a common theme in five th century bc greek art in some vase paintings he is shown wearing a deerskin in others antlers sprout from his head pictures of artemis surprised by actaeon while bathing are found among pompeian wall paintings the theme was one of many revived in the renaissance see for example the death of actaeon by titian references the oxford classical dictionary s v actaeon ovid metamorphoses three one three eight ff euripedes bacchae three three seven four zero diodorus siculus four eight one four shapeshifting greek mythological people the term anglican from |
anglia the latin name for england describes the people and churches that follow the religious traditions developed by the established church of england the anglican communion codifies the anglican relationship to the church of england as a theologically broad and often diverging community of churches which holds the english church as its mother institution adherents of anglicanism within the anglican communion that is in communion with the see of canterbury worldwide number around seven zero million but there are numerous denominations which consider themselves anglican but which are out of the communion the issue of catholic and protestant affiliation is often confusing whilst many anglicans regard themselves as being within the protestant tradition many other anglicans especially anglo catholics do not consider themselves as protestants the church of england claims explicitly that the church upholds the catholic faith the athanasian creed states and the catholic faith is this that we worship one god in trin |
ity and trinity in unity neither confounding the persons nor dividing the substance the phrase catholic church by definition means the universal christian church but also holds the sense of the church in its fullness ultimately the anglican church considers itself as being both catholic stressing its continuity with the ancient church and reformed protestant noting that the church does not accept the universal infallible authority of the pope the conduct of eucharistically centred worship services is in keeping with the catholic liturgical tradition and the communion emphasises its status of full communion with the old catholic utrecht union a small community of churches which split from the roman catholic church in one eight seven zero over the doctrine of papal infallibility on the other hand the development of anglicanism as a distinctive theological tradition is also deeply connected with the protestant reformation as with the orthodox and roman catholic churches but unlike most protestant churches anglic |
ans claim authority within the church through apostolic succession from the first followers of jesus the anglican roman catholic international consultation actually reached agreement on the doctrine of the ministry in their elucidation of one nine seven nine but the roman catholic church continues to hold that anglican orders are not valid in contrast anglican orders are recognized as valid by the old catholics and lutherans communions which also consider themselves the catholic church anglicans traditionally date their church back at least to its first archbishop of canterbury saint augustine of canterbury in the six th century and even centuries earlier to the roman occupation many anglicans point out that christian missionaries existed in the british lands from the one st century with bishops established at glastonbury by commission from the apostle philip they consider celtic christianity a prefix of their faith since many celtic elements remained even after the synod of whitby conformed to roman customs |
well after the establishment of the canterbury see they also point out that bishops from the british isles participated in the early ecumenical councils most significantly pelagius the monk who was almost successful in stopping original sin from becoming an official church doctrine origins see also history of the church of england while anglicans acknowledge that the schism from papal authority under henry viii of england led to the church of england existing as a separate entity they also stress its continuity with the pre reformation church of england the organisational machinery of the church of england was in place by the time of the synod of hertford in six seven two six seven three ad when the english bishops were for the first time able to act as one body under the leadership of the archbishop of canterbury since the elizabethan religious settlement the church of england has enjoyed a heritage that is both catholic and protestant with the british monarch as its supreme governor contrary to much popular |
belief the british monarch is not the constitutional head of the church of england and it is incorrect to refer to the monarch as such the monarch has no constitutional role in anglican churches in other parts of the world although the prayer books of several countries maintain prayers for our sovereign lady elizabeth and the versicle at morning prayer o lord save the queen which in the united states prayer book for example is altered to o lord save the state nonetheless the english reformation was initially driven by the dynastic goals of henry viii of england who in his quest for a queen to bear him a male heir found it necessary and profitable to replace the papacy with the english crown henry s need for a legitimate male heir was real england s previous experience in the twelfth century of rule by a queen had been a disaster that no one wished to see repeated see empress matilda it was not henry s intention to found a new church he was well informed enough about history to know that the powers he was cla |
iming were those which had been exercised by european monarchs over the church in their dominions since the time of constantine and that what had changed since then had been the growth of papal power the act of supremacy put henry at the head of the church in one five three four while acts such as the dissolution of the monasteries put huge amounts of church land and property into the hands of the crown and ultimately into those of the english nobility these created vested interests which made a powerful material incentive to support a separate christian church in england under the rule of the monarch the theological justification for anglican distinctiveness was begun by the archbishop of canterbury thomas cranmer and continued by other thinkers such as richard hooker and lancelot andrewes cranmer had studied in europe and was influenced by the ideas of the reformation and had also married despite being a priest because cranmer and other leaders of the church of england had been ordained by bishops in the ap |
ostolic succession and passed on that ordination to their successors anglicans consider that they have retained the historic apostolic succession but differ as to how significant this is during the short reign of edward vi henry s son cranmer was able to move the church of england significantly towards a more protestant calvinist position the first book of common prayer dates from this period this reform was reversed abruptly in the subsequent reign of queen mary only under queen elizabeth i was the english church established as a reformed catholic church that was accepting of calvinistic and evangelical theology in the one six th century religious life was an important part of the cement which held society together differences in religion were likely to lead to civil unrest at the very least with treason and foreign invasion possibly thrown in as well elizabeth s solution to the problem of minimising bloodshed over religion in her dominions was a religious settlement which prescribed a fixed sparer form of w |
orship in the vernacular in which everyone was expected to take part i e common prayer but a belief system formulated in a way that would allow people with different understandings of what the bible taught to give assent the protestant principle that all things must be proved by scripture was endorsed in article vi of the thirty nine articles so that no one could be required to believe anything unless it could be clearly proved from the scriptures this did recognise that there were areas where the bible did not give clear cut teaching where differences of opinion among christians were legitimate the bulk of the population was willing to go along with elizabeth s religious settlement but extremists at both ends of the theological spectrum would have nothing to do with it and cracks in the fa ade of religious unity in england were appearing for the next century there were significant swings back and forth between the puritans and those with a less reformed understanding of anglicanism it must be understood that |
the concept of religious freedom was in those days neither understood nor accepted by many people and that the groups involved in the struggle were aiming for control not freedom by continental standards the level of violence over religion was not high but among the casualties were a king charles i and an archbishop of canterbury william laud the final outcome in one six six zero after the restoration of charles ii was not too far removed from the elizabethan ideal one difference was that the ideal of encompassing all the people of england in one religious organisation taken for granted by the tudors had to be abandoned the religious landscape of england assumed its present form with an anglican established church occupying the middle ground and the two extremes roman catholic and those puritans who dissented from the establishment too strong to be suppressed altogether having to continue their existence outside the national church rather than controlling it the english reformation may be said to have ended |
at this point the elizabethan settlement failed in that it was never able to gain the assent of the entire english people yet as the anglican form of christianity is now flourishing in many parts of the world far away from england it may possibly have succeeded beyond the wildest expectations of anybody alive in the sixteenth and seventeenth centuries leadership the archbishop of canterbury has a precedence of honour over the other archbishops of the anglican communion he is recognised as primus inter pares or first amongst equals the archbishop of canterbury however does not exercise any direct authority in the provinces outside england the current archbishop of canterbury rowan williams as former archbishop of wales is the first primate appointed from outside the church of england since the reformation all anglican priests have apostolic succession since the reign of henry viii ultimate authority in the church of england has been vested in the reigning monarch since the time of elizabeth i the sovereign s t |
itle has been supreme governor rather than head of the church of england in practice this means that the monarch has the responsibility of seeing that the administrative machinery of the church is running smoothly and in particular that new bishops are appointed when needed today this responsibility is discharged by the prime minister anglican churches outside england do not have this relationship with the british monarch however it remains the case that the archbishop of canterbury leader of the worldwide anglican communion is appointed by the crown of the united kingdom in theory in practice by the prime minister churches anglicanism is most commonly identified with the established church of england but anglican churches exist in most parts of the world in some countries e g the united states scotland the anglican church is known as episcopal from the latin episcopus bishop which comes from a greek word literally meaning an overseer some anglican churches are not in communion with the archbishop of canterbu |
ry but consider themselves anglican because they retain practices of the church of england and the book of common prayer each national church or province is headed by a primate called a primus in the scottish episcopal church an archbishop in most countries a presiding bishop in the episcopal church usa and a prime bishop in the philippine episcopal church these churches are divided into a number of dioceses usually corresponding to state or metropolitan divisions there are three orders of the ordained ministry deacon priest and bishop no requirement is made for clerical celibacy and women may be ordained as deacons in almost all provinces as priests in some and as bishops in a few provinces religious orders of monks brothers sisters and nuns were suppressed in england during the reformation but have made a reappearance in victorian times and thrive today those anglican churches in communion with the see of canterbury constitute the anglican communion a formal organisation made up of churches at the national |
level however there are a large number of denominations albeit insignificant in terms of number of adherents which call themselves anglican that are known as the continuing church movement and do not acknowledge the anglican communion they are generally conservative to traditionalist and to a varying degree anglo catholic in their doctrinal orientation but tend to side politically with evangelicals of the right some however are at the extreme evangelical end of the churchmanship spectrum such as the church of england in south africa not in communion in canterbury but in communion with the diocese of sydney and the reformed episcopal church they consider the church of england and the episcopal church in the united states of america as well as some other member churches of the anglican communion to have departed from the historic faith by ordaining women by ordaining openly gay people by altering the theological emphases of the one nine two eight book of common prayer of the episcopal church of the united state |
s or the one six six two book of common prayer of the church of england and by loosening the church s traditional regulations concerning sexual and marital matters there are also those independent jurisdictions such as the national anglican catholic church of the united states which uses anglican catholic and lutheran principles in their doctrine in the indian subcontinent anglican churches have entered into formal union with evangelical protestant denominations while remaining part of the anglican communion and indeed bringing their presbyterian and other historically non anglican fellows along with them as a percentage of the total population these united churches are not significant but numerically they are very substantial other than in bangladesh see church of north india church of south india church of pakistan and church of bangladesh doctrine anglicans look for authority in the formula of richard hooker in the experience of scripture reason and tradition the practices and writings of the historical ch |
urch while it is often taught that these three are of equal value using an image of a three legged stool the anglican formularies have always pointed out that scripture containeth all things necessary to salvation so that whatsoever is not read therein nor may be proved thereby is not to be required of any man that it should be believed as an article of the faith or be thought requisite or necessary to salvation article vi the anglican thirty nine articles of religion historically anglicans have regarded the bible the three creeds nicene creed apostles creed and athanasian creed the thirty nine articles of religion and the book of common prayer one six six two as the principal norms of doctrine thus some have said that the anglican church retains much of the liturgy of the roman catholic church but is tolerant of reformed doctrine this state of affairs is a consequence of the elizabethan religious settlement the traditional liturgy of anglicanism the one six six two book of common prayer has been considered t |
oo catholic by those of puritan leanings in the one six th century and evangelicals in later periods and too evangelical by those of anglo catholic leanings this distinction is routinely a matter of debate both within specific anglican churches and throughout the anglican communion by members themselves since the oxford movement of the mid one nine th century many churches of the communion have embraced and extended liturgical and pastoral practices dissimilar with most reformed protestant theology this extends beyond the ceremony of high church services to even more theologically significant territory some anglican clergy practise all seven of the sacraments in a marked way in departure from the teaching of early protestant thinkers like john calvin and martin luther even though opinions vary about the best way to understand these sacramental rites for example some anglican clergy will hear private confessions from their parishioners a practice widely discontinued in protestant denominations nevertheless whi |
le anglo catholic practices particularly liturgical ones have become much more mainstream within the denomination over the last century there remain many areas where practices and beliefs remain on the more protestant or evangelical side of the debate churchmanship anglicanism has always been characterised by diversity in theology and the ceremonial or lack thereof of the liturgy different individuals groups parishes dioceses and national churches may identify more with catholic traditions and theology or alternatively with the principles of evangelicalism some anglicans follow such devotional practices common among roman catholics as solemn benediction of the reserved sacrament use of the rosary or of anglican prayer beads and prayer to the departed saints which is contrary to the teaching of some of the english reformers some give greater weight to the deuterocanonical books of the bible see biblical canon officially anglican teaching is that these books may be read in church for their instruction in morals |
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