The expansion of the universe is the increase in distance between gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion; the universe does not expand "into" anything and does not require space to exist "outside" it. To any observer in the universe, it appears that all but the nearest galaxies (which are bound to each other by gravity) recede at speeds that are proportional to their distance from the observer, on average. While objects cannot move faster than light, this limitation only applies with respect to local reference frames and does not limit the recession rates of cosmologically distant objects.

Cosmic expansion is a key feature of Big Bang cosmology. It can be modeled mathematically with the Friedmann–Lemaître–Robertson–Walker metric (FLRW), where it corresponds to an increase in the scale of the spatial part of the universe's spacetime metric tensor (which governs the size and geometry of spacetime). Within this framework, the separation of objects over time is associated with the expansion of space itself. However, this is not a generally covariant description but rather only a choice of coordinates. Contrary to common misconception, it is equally valid to adopt a description in which space does not expand and objects simply move apart while under the influence of their mutual gravity. Although cosmic expansion is often framed as a consequence of general relativity, it is also predicted by Newtonian gravity.

According to inflation theory, during the inflationary epoch about 10−32 of a second after the Big Bang, the universe suddenly expanded, and its volume increased by a factor of at least 1078 (an expansion of distance by a factor of at least 1026 in each of the three dimensions). This would be equivalent to expanding an object 1 nanometer (10−9 m, about half the width of a molecule of DNA) in length to one approximately 10.6 light years (about 1017 m or 62 trillion miles) long. Cosmic expansion subsequently decelerated to much slower rates, until at around 9.8 billion years after the Big Bang (4 billion years ago) it began to gradually expand more quickly, and is still doing so. Physicists have postulated the existence of dark energy, appearing as a cosmological constant in the simplest gravitational models, as a way to explain this late-time acceleration. According to the simplest extrapolation of the currently favored cosmological model, the Lambda-CDM model, this acceleration becomes more dominant into the future.

History

In 1912, Vesto M. Slipher discovered that light from remote galaxies was redshifted, which was later interpreted as galaxies receding from the Earth. In 1922, Alexander Friedmann used Einstein field equations to provide theoretical evidence that the universe is expanding.

Swedish astronomer Knut Lundmark was the first person to find observational evidence for expansion in 1924. According to Ian Steer of the NASA/IPAC Extragalactic Database of Galaxy Distances, "Lundmark's extragalactic distance estimates were far more accurate than Hubble's, consistent with an expansion rate (Hubble constant) that was within 1% of the best measurements today."

In 1927, Georges Lemaître independently reached a similar conclusion to Friedmann on a theoretical basis, and also presented observational evidence for a linear relationship between distance to galaxies and their recessional velocity. Edwin Hubble observationally confirmed Lundmark's and Lemaître's findings in 1929. Assuming the cosmological principle, these findings would imply that all galaxies are moving away from each other.

Astronomer Walter Baade recalculated the size of the known universe in the 1940s, doubling the previous calculation made by Hubble in 1929. He announced this finding to considerable astonishment at the 1952 meeting of the International Astronomical Union in Rome. For most of the second half of the 20th century, the value of the Hubble constant was estimated to be between 50 and  (Mega Parsec).

On 13 January 1994, NASA formally announced a completion of its repairs related to the main mirror of the Hubble Space Telescope allowing for sharper images and, consequently, more accurate analyses of its observations. Briefly after the repairs were made, Wendy Freedman's 1994 Key Project analyzed the recession velocity of M100 from the core of the Virgo cluster, offering a Hubble constant measurement of 80±17 km s−1 Mpc−1. Later the same year, Adam Riess et al used an empirical method of visual band light shape curves to more finely estimate the luminosity of Type Ia supernovae. This further minimized the systemic measurement errors of the Hubble constant to 67±7 km s−1 Mpc−1. Reiss's measurements on the recession velocity of the nearby Virgo cluster more closely agree with subsequent and independent analyses of Cepheid variable calibrations of 1a supernovae, which estimates a Hubble Constant of 73±7km s−1 Mpc−1. In 2003, David Spergel's analysis of the Cosmic microwave background during the first year observations of the Wilkinson Microwave Anisotropy Probe satellite (WMAP) further agreed with the estimated expansion rates for local galaxies, 72±5 km s−1 Mpc−1.

Structure of cosmic expansion

The universe at the largest scales is observed to be homogeneous (the same everywhere) and isotropic (the same in all directions), consistent with the cosmological principle. These constraints demand that any expansion of the universe accord with Hubble's law, in which objects recede from each observer with velocities proportional to their positions with respect to that observer. That is, recession velocities  scale with (observer-centered) positions  according to

where the Hubble rate  quantifies the rate of expansion.  is a function of cosmic time.

Dynamics of cosmic expansion

The expansion of the universe can be understood as a consequence of an initial impulse (possibly due to inflation), which sent the contents of the universe flying apart. The mutual gravitational attraction of the matter and radiation within the universe gradually slows this expansion over time, but expansion nevertheless continues due to momentum left over from the initial impulse. Also, certain exotic relativistic fluids, such as dark energy and inflation, exert gravitational repulsion in the cosmological context, which accelerates the expansion of the universe. A cosmological constant also has this effect.

Mathematically, the expansion of the universe is quantified by the scale factor, , which is proportional to the average separation between objects, such as galaxies. The scale factor is a function of time and is conventionally set to be  at the present time. Because the universe is expanding,  is smaller in the past and larger in the future. Extrapolating back in time with certain cosmological models will yield a moment when the scale factor was zero; our current understanding of cosmology sets this time at 13.787 ± 0.020 billion years ago. If the universe continues to expand forever, the scale factor will approach infinity in the future. It is also possible in principle for the universe to stop expanding and begin to contract, which corresponds to the scale factor decreasing in time.

The scale factor  is a parameter of the FLRW metric, and its time evolution is governed by the Friedmann equations. The second Friedmann equation,

shows how the contents of the universe influence its expansion rate. Here,  is the gravitational constant,  is the energy density within the universe,  is the pressure,  is the speed of light, and  is the cosmological constant. A positive energy density leads to deceleration of the expansion, , and a positive pressure further decelerates expansion. On the other hand, sufficiently negative pressure with  leads to accelerated expansion, and the cosmological constant also accelerates expansion. Nonrelativistic matter is essentially pressureless, with , while a gas of ultrarelativistic particles (such as a photon gas) has positive pressure . Negative-pressure fluids, like dark energy, are not experimentally confirmed, but the existence of dark energy is inferred from astronomical observations.

Distances in the expanding universe

Comoving coordinates

In an expanding universe, it is often useful to study the evolution of structure with the expansion of the universe factored out. This motivates the use of comoving coordinates, which are defined to grow proportionally with the scale factor. If an object is moving only with the Hubble flow of the expanding universe, with no other motion, then it remains stationary in comoving coordinates. The comoving coordinates are the spatial coordinates in the FLRW metric.

Shape of the universe

The universe is a four-dimensional spacetime, but within a universe that obeys the cosmological principle, there is a natural choice of three-dimensional spatial surface. These are the surfaces on which observers who are stationary in comoving coordinates agree on the age of the universe. In a universe governed by special relativity, such surfaces would be hyperboloids, because relativistic time dilation means that rapidly-receding distant observers' clocks are slowed, so that spatial surfaces must bend "into the future" over long distances.  However, within general relativity, the shape of these comoving synchronous spatial surfaces is affected by gravity. Current observations are consistent with these spatial surfaces being geometrically flat (so that, for example, the angles of a triangle add up to 180 degrees).

Cosmological horizons

An expanding universe typically has a finite age. Light, and other particles, can only have propagated a finite distance. The comoving distance that such particles can have covered over the age of the universe is known as the particle horizon, and the region of the universe that lies within our particle horizon is known as the observable universe.

If the dark energy that is inferred to dominate the universe today is a cosmological constant, then the particle horizon converges to a finite value in the infinite future. This implies that the amount of the universe that we will ever be able to observe is limited. Many systems exist whose light can never reach us, because there is a cosmic event horizon induced by the repulsive gravity of the dark energy.

When studying the evolution of structure within the universe, a natural scale emerges, known as the Hubble horizon. Cosmological perturbations much larger than the Hubble horizon are not dynamical, because gravitational influences do not have time to propagate across them, while perturbations much smaller than the Hubble horizon are straightforwardly governed by Newtonian gravitational dynamics.

Consequences of cosmic expansion

Velocities and redshifts

An object's peculiar velocity is its velocity with respect to the comoving coordinate grid, i.e., with respect to the average motion of the surrounding material. It is a measure of how a particle's motion deviates from the Hubble flow of the expanding universe. The peculiar velocities of nonrelativistic particles decay as the universe expands, in inverse proportion with the cosmic scale factor. This can be understood as a self-sorting effect. A particle that is moving in some direction gradually overtakes the Hubble flow of cosmic expansion in that direction, asymptotically approaching material with the same velocity as its own.

More generally, the peculiar momenta of both relativistic and nonrelativistic particles decay in inverse proportion with the scale factor. For photons, this leads to the cosmological redshift. While the cosmological redshift is often explained as the stretching of photon wavelengths due to "expansion of space", it is more naturally viewed as a consequence of the Doppler effect.

Temperature

The universe cools as it expands. This follows from the decay of particles' peculiar momenta, as discussed above. It can also be understood as adiabatic cooling. The temperature of ultrarelativistic fluids, often called "radiation" and including the cosmic microwave background, scales inversely with the scale factor (i.e. ). The temperature of nonrelativistic matter drops more sharply, scaling as the inverse square of the scale factor (i.e. ).

Density

The contents of the universe dilute as it expands. The number of particles within a comoving volume remains fixed (on average), while the volume expands. For nonrelativistic matter, this implies that the energy density drops as , where  is the scale factor.

For ultrarelativistic particles ("radiation"), the energy density drops more sharply as . This is because in addition to the volume dilution of the particle count, the energy of each particle (including the rest mass energy) also drops significantly due to the decay of peculiar momenta.

In general, we can consider a perfect fluid with pressure , where  is the energy density. The parameter  is the equation of state parameter. The energy density of such a fluid drops as

Nonrelativistic matter has  while radiation has . For an exotic fluid with negative pressure, like dark energy, the energy density drops more slowly; if  it remains constant in time. If , corresponding to phantom energy, the energy density grows as the universe expands.

Expansion history

Cosmic inflation

Inflation is a period of accelerated expansion hypothesized to have occurred at a time of around 10-32 seconds. It would have been driven by the inflaton, a field that has a positive-energy false vacuum state. Inflation was originally proposed to explain the absence of exotic relics predicted by grand unified theories, such as magnetic monopoles, because the rapid expansion would have diluted such relics. It was subsequently realized that the accelerated expansion would also solve the horizon problem and the flatness problem. Additionally, quantum fluctuations during inflation would have created initial variations in the density of the universe, which gravity later amplified to yield the observed spectrum of matter density variations.

During inflation, the cosmic scale factor grows exponentially in time. In order to solve the horizon and flatness problems, inflation must have lasted long enough that the scale factor grew by at least a factor of e60 (about 1026).

Radiation epoch

The history of the universe after inflation but before a time of about 1 second is largely unknown. However, the universe is known to have been dominated by ultrarelativistic Standard-Model particles, conventionally called radiation, by the time of neutrino decoupling at about 1 second. During radiation domination, cosmic expansion decelerated, with the scale factor growing proportionally with the square root of the time.

Matter epoch

Since radiation redshifts as the universe expands, eventually nonrelativistic matter comes to dominate the energy density of the universe. This transition happened at a time of about 50 thousand years after the Big Bang. During the matter-dominated epoch, cosmic expansion also decelerated, with the scale factor growing as the 2/3 power of the time (). Also, gravitational structure formation is most efficient when nonrelativistic matter dominates, and this epoch is responsible for the formation of galaxies and the large-scale structure of the universe.

Dark energy

Around 3 billion years ago, at a time of about 11 billion years, dark energy is believed to have begun to dominate the energy density of the universe. This transition comes about because dark energy does not dilute as the universe expands, instead maintaining a constant energy density. Similarly to inflation, dark energy drives accelerated expansion, such that the scale factor grows exponentially in time.

Measuring the expansion rate

The most direct way to measure the expansion rate is to independently measure the recession velocities and the distances of distant objects, such as galaxies. The ratio between these quantities gives the Hubble rate, in accordance with Hubble's law. Typically, the distance is measured using a standard candle, which is an object or event for which the intrinsic brightness is known. The object's distance can then be inferred from the observed apparent brightness. Meanwhile, the recession speed is measured through the redshift. Hubble used this approach for his original measurement of the expansion rate, by measuring the brightness of Cepheid variable stars and the redshifts of their host galaxies. More recently, using Type Ia supernovae, the expansion rate was measured to be H0 = . This means that for every million parsecs of distance from the observer, objects at that distance are receding at about .

Supernovae are observable at such great distances that the light travel time therefrom can approach the age of the universe. Consequently, they can be used to measure not only the present-day expansion rate but also the expansion history. In work that was awarded the 2011 Nobel Prize in Physics, supernova observations were used to determine that cosmic expansion is accelerating in the present epoch.

By assuming a cosmological model, e.g. the Lambda-CDM model, another possibility is to infer the present-day expansion rate from the sizes of the largest fluctuations seen in the Cosmic Microwave Background. A higher expansion rate would imply a smaller characteristic size of CMB fluctuations, and vice versa. The Planck collaboration measured the expansion rate this way and determined H0 = . There is a disagreement between this measurement and the supernova-based measurements, known as the Hubble tension.

A third option proposed recently is to use information from gravitational wave events (especially those involving the merger of neutron stars, like GW170817) to measure the expansion rate. Such measurements do not yet have the precision to resolve the Hubble tension.

In principle, the cosmic expansion history can also be measured by studying how redshifts, distances, fluxes, angular positions, and angular sizes of astronomical objects change over the course of the time that they are being observed. These effects are too small to have yet been detected. However, changes in redshift or flux could be observed by Square Kilometre Array or Extremely Large Telescope in the mid-2030s.

Conceptual considerations and misconceptions

Measuring distances in expanding space

At cosmological scales, the present universe conforms to Euclidean space, what cosmologists describe as geometrically flat, to within experimental error.

Consequently, the rules of Euclidean geometry associated with Euclid's fifth postulate hold in the present universe in 3D space. It is, however, possible that the geometry of past 3D space could have been highly curved. The curvature of space is often modeled using a non-zero Riemann curvature tensor in curvature of Riemannian manifolds. Euclidean "geometrically flat" space has a Riemann curvature tensor of zero.

"Geometrically flat" space has three dimensions and is consistent with Euclidean space. However, spacetime has four dimensions; it is not flat according to Einsten's general theory of relativity. Einstein's theory postulates that "matter and energy curve spacetime, and there is enough matter and energy to provide for curvature."

In part to accommodate such different geometries, the expansion of the universe is inherently general relativistic. It cannot be modeled with special relativity alone: though such models exist, they may be at fundamental odds with the observed interaction between matter and spacetime seen in the universe.

The images to the right show two views of spacetime diagrams that show the large-scale geometry of the universe according to the ΛCDM cosmological model. Two of the dimensions of space are omitted, leaving one dimension of space (the dimension that grows as the cone gets larger) and one of time (the dimension that proceeds "up" the cone's surface). The narrow circular end of the diagram corresponds to a cosmological time of 700 million years after the Big Bang, while the wide end is a cosmological time of 18 billion years, where one can see the beginning of the accelerating expansion as a splaying outward of the spacetime, a feature that eventually dominates in this model. The purple grid lines mark cosmological time at intervals of one billion years from the Big Bang. The cyan grid lines mark comoving distance at intervals of one billion light years in the present era (less in the past and more in the future). Note that the circular curling of the surface is an artifact of the embedding with no physical significance and is done for illustrative purposes; a flat universe does not curl back onto itself. (A similar effect can be seen in the tubular shape of the pseudosphere.)

The brown line on the diagram is the worldline of Earth (or more precisely its location in space, even before it was formed). The yellow line is the worldline of the most distant known quasar. The red line is the path of a light beam emitted by the quasar about 13 billion years ago and reaching Earth at the present day. The orange line shows the present-day distance between the quasar and Earth, about 28 billion light years, which is a larger distance than the age of the universe multiplied by the speed of light, ct.

According to the equivalence principle of general relativity, the rules of special relativity are locally valid in small regions of spacetime that are approximately flat. In particular, light always travels locally at the speed c; in the diagram, this means, according to the convention of constructing spacetime diagrams, that light beams always make an angle of 45° with the local grid lines. It does not follow, however, that light travels a distance ct in a time t, as the red worldline illustrates. While it always moves locally at c, its time in transit (about 13 billion years) is not related to the distance traveled in any simple way, since the universe expands as the light beam traverses space and time. The distance traveled is thus inherently ambiguous because of the changing scale of the universe. Nevertheless, there are two distances that appear to be physically meaningful: the distance between Earth and the quasar when the light was emitted, and the distance between them in the present era (taking a slice of the cone along the dimension defined as the spatial dimension). The former distance is about 4 billion light years, much smaller than ct, whereas the latter distance (shown by the orange line) is about 28 billion light years, much larger than ct. In other words, if space were not expanding today, it would take 28 billion years for light to travel between Earth and the quasar, while if the expansion had stopped at the earlier time, it would have taken only 4 billion years.

The light took much longer than 4 billion years to reach us though it was emitted from only 4 billion light years away. In fact, the light emitted towards Earth was actually moving away from Earth when it was first emitted; the metric distance to Earth increased with cosmological time for the first few billion years of its travel time, also indicating that the expansion of space between Earth and the quasar at the early time was faster than the speed of light. None of this behavior originates from a special property of metric expansion, but rather from local principles of special relativity integrated over a curved surface.

Topology of expanding space
Over time, the space that makes up the universe is expanding. The words 'space' and 'universe', sometimes used interchangeably, have distinct meanings in this context. Here 'space' is a mathematical concept that stands for the three-dimensional manifold into which our respective positions are embedded while 'universe' refers to everything that exists including the matter and energy in space, the extra-dimensions that may be wrapped up in various strings, and the time through which various events take place. The expansion of space is in reference to this 3-D manifold only; that is, the description involves no structures such as extra dimensions or an exterior universe.

The ultimate topology of space is a posteriori – something that in principle must be observed – as there are no constraints that can simply be reasoned out (in other words there can not be any a priori constraints) on how the space in which we live is connected or whether it wraps around on itself as a compact space. Though certain cosmological models such as Gödel's universe even permit bizarre worldlines that intersect with themselves, ultimately the question as to whether we are in something like a "Pac-Man universe" where if traveling far enough in one direction would allow one to simply end up back in the same place like going all the way around the surface of a balloon (or a planet like the Earth) is an observational question that is constrained as measurable or non-measurable by the universe's global geometry. At present, observations are consistent with the universe being infinite in extent and simply connected, though we are limited in distinguishing between simple and more complicated proposals by cosmological horizons. The universe could be infinite in extent or it could be finite; but the evidence that leads to the inflationary model of the early universe also implies that the "total universe" is much larger than the observable universe, and so any edges or exotic geometries or topologies would not be directly observable as light has not reached scales on which such aspects of the universe, if they exist, are still allowed. For all intents and purposes, it is safe to assume that the universe is infinite in spatial extent, without edge or strange connectedness.

Regardless of the overall shape of the universe, the question of what the universe is expanding into is one that does not require an answer according to the theories that describe the expansion; the way we define space in our universe in no way requires additional exterior space into which it can expand since an expansion of an infinite expanse can happen without changing the infinite extent of the expanse. All that is certain is that the manifold of space in which we live simply has the property that the distances between objects are getting larger as time goes on. This only implies the simple observational consequences associated with the metric expansion explored below. No "outside" or embedding in hyperspace is required for an expansion to occur. The visualizations often seen of the universe growing as a bubble into nothingness are misleading in that respect. There is no reason to believe there is anything "outside" of the expanding universe into which the universe expands.

Even if the overall spatial extent is infinite and thus the universe cannot get any "larger", we still say that space is expanding because, locally, the characteristic distance between objects is increasing. As an infinite space grows, it remains infinite.

Density of universe during expansion
Despite being extremely dense when very young and during part of its early expansion – far denser than is usually required to form a black hole – the universe did not re-collapse into a black hole. This is because commonly used calculations for gravitational collapse are usually based upon objects of relatively constant size, such as stars, and do not apply to rapidly expanding space such as the Big Bang.

Effects of expansion on small scales
The expansion of space is sometimes described as a force that acts to push objects apart. Though this is an accurate description of the effect of the cosmological constant, it is not an accurate picture of the phenomenon of expansion in general.

In addition to slowing the overall expansion, gravity causes local clumping of matter into stars and galaxies. Once objects are formed and bound by gravity, they "drop out" of the expansion and do not subsequently expand under the influence of the cosmological metric, there being no force compelling them to do so.

There is no difference between the inertial expansion of the universe and the inertial separation of nearby objects in a vacuum; the former is simply a large-scale extrapolation of the latter.

Once objects are bound by gravity, they no longer recede from each other. Thus, the Andromeda galaxy, which is bound to the Milky Way galaxy, is actually falling towards us and is not expanding away. Within the Local Group, the gravitational interactions have changed the inertial patterns of objects such that there is no cosmological expansion taking place. Beyond the Local Group, the inertial expansion is measurable, though systematic gravitational effects imply that larger and larger parts of space will eventually fall out of the "Hubble Flow" and end up as bound, non-expanding objects up to the scales of superclusters of galaxies. Such future events are predicted by knowing the precise way the Hubble Flow is changing as well as the masses of the objects to which we are being gravitationally pulled. Currently, the Local Group is being gravitationally pulled towards either the Shapley Supercluster or the "Great Attractor" with which, if dark energy were not acting, we would eventually merge and no longer see expand away from us after such a time.

A consequence of metric expansion being due to inertial motion is that a uniform local "explosion" of matter into a vacuum can be locally described by the FLRW geometry, the same geometry that describes the expansion of the universe as a whole and was also the basis for the simpler Milne universe, which ignores the effects of gravity. In particular, general relativity predicts that light will move at the speed c with respect to the local motion of the exploding matter, a phenomenon analogous to frame dragging.

The situation changes somewhat with the introduction of dark energy or a cosmological constant. A cosmological constant due to a vacuum energy density has the effect of adding a repulsive force between objects that is proportional (not inversely proportional) to distance. Unlike inertia it actively "pulls" on objects that have clumped together under the influence of gravity, and even on individual atoms. However, this does not cause the objects to grow steadily or to disintegrate; unless they are very weakly bound, they will simply settle into an equilibrium state that is slightly (undetectably) larger than it would otherwise have been. As the universe expands and the matter in it thins, the gravitational attraction decreases (since it is proportional to the density), while the cosmological repulsion increases. Thus, the ultimate fate of the ΛCDM universe is a near vacuum expanding at an ever-increasing rate under the influence of the cosmological constant. However, gravitationally bound objects like the Milky Way do not expand, and the Andromeda galaxy is moving fast enough towards us that it will still merge with the Milky Way in around 3 billion years.

Metric expansion and speed of light
At the end of the early universe's inflationary period, all the matter and energy in the universe was set on an inertial trajectory consistent with the equivalence principle and Einstein's general theory of relativity. This is when the precise and regular form of the universe's expansion had its origin (that is, matter in the universe is separating because it was separating in the past due to the inflaton field).

While special relativity prohibits objects from moving faster than light with respect to a local reference frame where spacetime can be treated as flat and unchanging, it does not apply to situations where spacetime curvature or evolution in time become important. These situations are described by general relativity, which allows the separation between two distant objects to increase faster than the speed of light, although the definition of "distance" here is somewhat different from that used in an inertial frame. The definition of distance used here is the summation or integration of local comoving distances, all done at constant local proper time. For example, galaxies that are farther than the Hubble radius, approximately 4.5 gigaparsecs or 14.7 billion light-years, away from us have a recession speed that is faster than the speed of light. Visibility of these objects depends on the exact expansion history of the universe. Light that is emitted today from galaxies beyond the more-distant cosmological event horizon, about 5 gigaparsecs or 16 billion light-years, will never reach us, although we can still see the light that these galaxies emitted in the past. Because of the high rate of expansion, it is also possible for a distance between two objects to be greater than the value calculated by multiplying the speed of light by the age of the universe. These details are a frequent source of confusion among amateurs and even professional physicists. Due to the non-intuitive nature of the subject and what has been described by some as "careless" choices of wording, certain descriptions of the metric expansion of space and the misconceptions to which such descriptions can lead are an ongoing subject of discussion within the fields of education and communication of scientific concepts.

Common analogies for cosmic expansion
The expansion of the universe is often illustrated with conceptual models where an expanding object is taken to represent expanding space. Note that these models can be misleading to the extent that they give the false impression that expanding space can carry objects with it. In reality, the expansion of the universe corresponds only to the inertial motion of objects away from one another.

In the "ant on a rubber rope model" one imagines an ant (idealized as pointlike) crawling at a constant speed on a perfectly elastic rope that is constantly stretching. If we stretch the rope in accordance with the ΛCDM scale factor and think of the ant's speed as the speed of light, then this analogy is numerically accurate – the ant's position over time will match the path of the red line on the embedding diagram above.

In the "rubber sheet model" one replaces the rope with a flat two-dimensional rubber sheet that expands uniformly in all directions. The addition of a second spatial dimension raises the possibility of showing local perturbations of the spatial geometry by local curvature in the sheet.

In the "balloon model" the flat sheet is replaced by a spherical balloon that is inflated from an initial size of zero (representing the big bang). A balloon has positive Gaussian curvature while observations suggest that the real universe is spatially flat, but this inconsistency can be eliminated by making the balloon very large so that it is locally flat to within the limits of observation. This analogy is potentially confusing since it wrongly suggests that the big bang took place at the center of the balloon. In fact points off the surface of the balloon have no meaning, even if they were occupied by the balloon at an earlier time.

In the "raisin bread model" one imagines a loaf of raisin bread expanding in an oven. The loaf (space) expands as a whole, but the raisins (gravitationally bound objects) do not expand; they merely grow farther away from each other.

See also

Comoving and proper distances

Notes

References

Printed references
 Eddington, Arthur. The Expanding Universe: Astronomy's 'Great Debate', 1900–1931. Press Syndicate of the University of Cambridge, 1933.
 Liddle, Andrew R. and Lyth, David H. Cosmological Inflation and Large-Scale Structure. Cambridge University Press, 2000.
 Lineweaver, Charles H. and Davis, Tamara M. "Misconceptions about the Big Bang", Scientific American, March 2005 (non-free content).
 Mook, Delo E. and Thomas Vargish. Inside Relativity. Princeton University Press, 1991.

External links

 Swenson, Jim, Answer to a question about the expanding universe
 Felder, Gary, "The Expanding universe".
 NASA's WMAP team offers an "Explanation of the universal expansion" at an elementary level
 Hubble Tutorial from the University of Wisconsin Physics Department
 Expanding raisin bread from the University of Winnipeg: an illustration, but no explanation
 "Ant on a balloon" analogy to explain the expanding universe at "Ask an Astronomer". (The astronomer who provides this explanation is not specified.)

Physical cosmology
General relativity
Big Bang
Concepts in astronomy

Expansion of the universe


A design director is a position usually found within the software development, web development, product design, advertising, media, automotive or movie industries, but may be useful in other product focused organizations as well. The duties has similarities to that of a creative instructor but with a greater emphasis on technical design and production, rather than just creative and ideas. The design director oversees the design of branding, product, UI, UX,  Print, Advertising for a client, ensuring that the design elements fits in with the client's requirements and the product fits the design brief the client  wish to promote for their company or product. However, unlike a creative director, the design director is also responsible for the overall quality of the final creative work and the quality of the project's design elements.

Whereas distinction between the two positions is that advertising creative directors are usually promoted from copywriting or art directing positions. Design directors, on the other hand, are promoted from senior designer positions. Design directors also require a much greater technical understanding of design process and techniques with cross platform and multi-disciplinary team application of their work also common place. As a role design directors are not only concerned with the creative elements, but also business, production and user facing experiences.

See also
 Design
 Creativity
 Artistic inspiration
 Communication

References

Advertising occupations
Arts occupations
Communication design
Design

Design director


The northern pearl dace (Margariscus nachtriebi) is a freshwater ray-finned fish in the family Cyprinidae, the carps and minnows. It occurs in Atlantic, Hudson Bay, Great Lakes, and Mississippi River basins in the northern United States and  Canada. Its preferred habitat is cool, clear headwater streams, bog drainage streams, ponds and small lakes, and in stained, peaty waters of beaver ponds, usually over sand or gravel.

References

Margariscus
Freshwater fish of North America
Fish described in 1896

Northern pearl dace


Cornelius Johannes du Preez de Villiers, also known as CJ de Villiers (born 16 March 1986) is a South African cricketer. He is a tall (6'4") right-handed batsman and a right-arm fast-medium bowler, who plays for Free State and Titans cricket teams.

Career

de Villiers made his first-class debut in 2006, scoring a total of 49 runs and taking one wicket for Free State in a match against Namibia. He followed 19 wickets in his debut season with a haul of forty in 2007–08, which left him as the sixth highest wicket-taker of the season.

In 2008 de Villiers played in South Africa A's unofficial Test series against Sri Lanka A, taking 5 for 36 during Sri Lanka's first innings in the second match.

Notes

External links

1986 births
Living people
South African cricketers
Knights cricketers
Free State cricketers
University of Pretoria cricketers
People from Kroonstad

CJ de Villiers


Claude Marion Akins was an American actor (born May 25, 1926, in Nelson, Georgia - died January 27, 1994, in Altadena, California). With his big body and deep voice, Akins usually played the clever (or less than clever) tough guy, on the side of good or bad, in movies and television. He is famous as Sheriff Lobo in the 1970s TV series B.J. and the Bear, and later The Misadventures of Sheriff Lobo, a spinoff series.

Other websites

Safety Shorts

American television actors
American movie actors
Actors from Georgia (U.S. state)
1926 births
1994 deaths

Claude Akins


Happy Journey is a 2014 Malayalam drama film written by Arunlal Ramachandran and directed by Boban Samuel, starring Jayasurya, Aparna Gopinath and Lal. The film is produced by Ashiq Usman under the banner of Milestone Cinemas and features music composed by Gopi Sunder, whilst cinematography is handled by Mahesh Raj and is edited by Lijo Paul.

Plot
The story narrates the life of a young man from Fort Kochi named Aaron, who loses his eyesight during his school days in an accident who then to find a place in the Indian cricket team for the blind.

Cast
Jayasurya as Aaron
Aparna Gopinath as Ziya Sidharth
Lal as Gopikrishnan
Lalu Alex
Balu Varghese as Freddy
Chemban Vinod Jose
Nizhalgal Ravi
Lena as annie
Indian Pallassery as Paanchi
Ramshad
Neeraj Madhav as Santhosh

Production

Development
Boban Samuel who had debuted into Malayalam film industry as a director through the film Janapriyan had announced a project before his film Romans starring Jayasurya who played the lead role in his debut venture. Although those projects didn't rise after 2 years, scriptwriter Arunlal who made his debut with 10:30 am Local Call  and later went on to do Thank You starring Jayasurya in the lead. Through that connection with the lead actor, he pitched the plot to the actor who had contacted Boban Samuel who instantly wanted to do the film, as it essays a story of a blind cricketer. Ashiq Usman chose to produce the film under the banner of Milestone Cinemas after Arikil Oraal. The editor was chosen to Lijo Paul, Art Direction by Vinesh Banglan, Sreya Aravind was chosen to be the costume designer and makeup by Ronex Xavier. Associate directors are Titus Alexander and Pranav Krishna, production controller was Sreekumar A.D., Stills by Antony Jo and Media designs by Ideas Inc.  The film was untitled until halfway through the filming where the title "Happy Journey was chosen, the news was confirmed by actor Jayasurya by saying that happy journeys is the synonyms to the theme of the film and was apt title for the film. It is based on the real-life story of a visually challenged Malayali youth, who is a part of the Indian blind cricket team."

Casting
Jayasurya was already initially cast as he contacted the director after hearing Arunlal's script.  the ramshad manjeri has been (ramo) is the script The casting was quickly taken place as several actors were chosen and initially cast such as Aparna Gopinath who debuted into acting in films through the film ABCD: American-Born Confused Desi and several other supporting actors were cast. Lena was chosen to play a mother that has significance in the plot.

Filming
The filming began at Kochi at 17 November 2013. Main locations of the film were in Ernakulam area such Edappally and Mattancherry.

Critical reception
Cine Shore gave the movie 2.75/5 stars, stating that "Happy Journey A Journey, Good in parts."

References

External links

2014 films
2010s Malayalam-language films
Films about blind people in India
Films about disability in India
Films scored by Gopi Sundar
Films shot in Kochi
Films directed by Boban Samuel

Happy Journey (2014 Malayalam film)


Hermann von Gottschall (16 October 1862, Posen – 7 March 1933, Görlitz) was a German chess master, son of the poet Rudolf Gottschall (since 1877: von Gottschall) who was also a noted chess player.

He took 3rd at Nuremberg 1883 (the 3rd DSB Congress, Hauptturnier A), won at Berlin 1883, tied for 13-14th at Hamburg 1885 (the 4th DSB-Congress, Isidor Gunsberg won), tied for 17-18th at Frankfurt 1887 (the 5th DSB-Congress, George Henry Mackenzie won), shared 2nd with Jacques Mieses, behind Siegbert Tarrasch, at Nuremberg 1888, and tied for 5-8th at Berlin 1890 (Emanuel Lasker and Berthold Lasker won).

Dr. Hermann von Gottschall won at Halle 1892, tied for 8-9th at Dresden 1892 (the 7th DSB-Congress, Tarrasch won), tied for 4-6th at Kiel 1893 (the 8th DSB-Congress, Curt von Bardeleben and Carl Walbrodt won), took 12th at Cologne 1898 (the 11th Amos Burn won), tied for 11-12th at Munich 1900 (the 12th Géza Maróczy, Harry Pillsbury and Carl Schlechter won), tied for 11-12th at Hannover 1902 (the 13th DSB-Congress, Dawid Janowski won), took 13th at Coburg 1904 (the 14th DSB-Congress, Bardeleben, Schlechter and Rudolf Swiderski won), tied for 15-16th at Barmen 1905 (Janowski and Maróczy won), and tied for 14-15th at Düsseldorf 1908 (the 16th DSB-Congress, Frank Marshall won).

In 1918, he took 3rd in Breslau. After World War I, he took 9th at Breslau 1925 (the 24th DSB-Congress, Efim Bogoljubow won), tied for 7-8th at Hannover 1926 (Aron Nimzowitsch won), and tied for 14-16th at Bautzen 1929.

He was the chief editor of the Deutsche Schachzeitung and the author of Kleine Problem-Schule (Leipzig 1885), Der sechste Kongress des Deutschen Schachbundes. Breslau 1889 (Leipzig 1890), Sammlung von Schachaufgaben (Leipzig 1898–1908), Adolf Anderssen, Altmeister deutscher Schachspielkunst (Leipzig 1912), and Streifzüge durch das Gebiet des Schachproblems (Berlin/Leipzig 1926).

References

1862 births
1933 deaths
Sportspeople from Poznań
German chess players
German chess writers
People from the Province of Posen

Hermann von Gottschall


Aulus Plautius (c. 44 BC – 1st century AD) was a Roman politician and senator who was appointed Suffect consul during the reign of Augustus.

Biography
The son of Aulus Plautius who was praetor urbanus in 51 BC, Plautius was appointed consul suffectus in 1 BC, replacing Cossus Cornelius Lentulus Gaetulicus. It has been speculated that he may have been the Aulus Plautius who was sent to Apulia by Augustus possibly around AD 9/10, with the task of interrogating and torturing slaves for some purpose, although it is more likely that this refers to his son Aulus Plautius who may have been involved with the suppression of a slave revolt in Apulia in AD 24.

Aulus Plautius was married to Vitellia, the grandaunt of the future Roman emperor Vitellius. They had at least two sons and one daughter: Aulus Plautius (suffect consul in 29 and who initiated the conquest of Britannia); Quintus Plautius (ordinary consul in 36), and Plautia, who was the wife of Publius Petronius.

It is unlikely that this was the Aulus Plautius who was the proconsular governor of Cilicia et Cyprus around the year 22/20 BC; that one may possibly have been his father.

Sources
 Giuseppe Camodeca: Problemi di storia sociale in Alife Romana. Le gentes senatorie degli Aedii e dei Granii e i ceti dirigenti del primo principato. In: Luigi Di Cosmo (Hrsg.): Il territorio Alifano. Archeologia, arte, storia. Atti del convegno, S. Angelo d'Alife, 26 aprile 1987. S. Angelo d'Alife 1990. S. 123–143.
 Werner Eck, Antonio Caballos, Fernando Fernández: Das Senatus consultum de Cn. Pisone patre. Beck, München 1996, , S. 105−106.
 Prosopographia Imperii Romani (PIR²). 1998, P 456.

References

1st-century BC Romans
1st-century Romans
Suffect consuls of Imperial Rome
Plautii
40s BC births
Year of birth uncertain
Year of death unknown

Aulus Plautius (consul 1 BC)


The Cenomanian-Turonian boundary event, also known as the Cenomanian-Turonian extinction, Cenomanian-Turonian oceanic anoxic event (OAE 2), and referred to also as the Bonarelli event, was one of two anoxic extinction events in the Cretaceous period. (The other being the earlier Selli event, or OAE 1a, in the Aptian.) The Cenomanian-Turonian oceanic anoxic event is considered to be the most recent truly global oceanic anoxic event in Earth's geologic history. Selby et al. in 2009 concluded the OAE 2 occurred approximately 91.5 ± 8.6 Ma, though estimates published by Leckie et al. (2002) are given as 93–94 Ma. The Cenomanian-Turonian boundary has been refined in 2012 to 93.9 ± 0.15 Ma. There was a large carbon cycle disturbance during this time period, signified by a large positive carbon isotope excursion. However, apart from the carbon cycle disturbance, there were also large disturbances in the ocean's nitrogen, oxygen, phosphorus, sulphur, and iron cycles.

Background
The Cenomanian and Turonian stages were first noted by D'Orbigny between 1843 and 1852. The global type section for this boundary is located in the Bridge Creek Limestone Member of the Greenhorn Formation near Pueblo, Colorado, which are bedded with the Milankovitch orbital signature. Here, a positive carbon-isotope event is clearly shown, although none of the characteristic, organic-rich black shale is present. It has been estimated that the isotope shift lasted approximately 850,000 years longer than the black shale event, which may be the cause of this anomaly in the Colorado type section. A significantly expanded OAE2 interval from southern Tibet documents a complete, more detailed, and finer-scale structures of the positive carbon isotope excursion that contains multiple shorter-term carbon isotope stages amounting to a total duration of 820 ±25 ka.

The level is also known as the Bonarelli event because of  layer of thick, black shale that marks the boundary and was first studied by  in 1891. It is characterized by interbedded black shales, chert and radiolarian sands and is estimated to span a 400,000-year interval. Planktonic foraminifera do not exist in this Bonarelli level, and the presence of radiolarians in this section indicates relatively high productivity and an availability of nutrients. In the Western Interior Seaway, the Cenomanian-Turonian boundary event is associated with the Benthonic Zone, characterised by a higher density of benthic foraminifera relative to planktonic foraminifera, although the timing of the appearance of the Benthonic Zone is not uniformly synchronous with the onset of the oceanic anoxic event and is thus cannot be used to consistently demarcate its beginning.

Timeline
The total duration of OAE2 has been estimated at 0.82 ±0.025 Myr or 0.71 ± 0.17 Myr. Biodiversity patterns of planktic foraminifera indicate that the Cenomanian-Turonian extinction occurred in five phases. Phase I, which took place from 313,000 to 55,000 years before the onset of the anoxic event, witnessed a stratified water column and high planktonic foraminiferal diversity, suggesting a stable marine environment. Phase II, characterised by significant environmental perturbations, lasted from 55,000 years before OAE2 until its onset and witnessed a decline in rotaliporids and heterohelicids, a zenith of schackoinids and hedbergellids, a 'large form eclipse' during which foraminifera exceeding 150 microns disappeared, and the start of a trend of dwarfism among many foraminifera. This phase also saw an enhanced oxygen minimum zone and increased productivity in surface waters. Phase III lasted for 100,000 to 900,000 years and was coincident with the Bonarelli Level's deposition and exhibited extensive proliferation of radiolarians, indicative of extremely eutrophic conditions. Phase IV lasted for around 35,000 years and was most notable for the increase in the abundance of hedbergellids and schackoinids, being extremely similar to Phase II, with the main difference being that rotaliporids were absent from Phase IV. Phase V was a recovery interval lasting 118,000 years and marked the end of the 'large form eclipse' that began in Phase II; heterohelicids and hedbergellids remained in abundance during this phase, pointing to continued environmental disturbance during this phase.

Causes

Climate change
Earth pronouncedly warmed just before the beginning of OAE2. The Cenomanian-Turonian interval represents one of the hottest intervals of the entire Phanerozoic eon, and it boasted the highest carbon dioxide concentrations of the Cretaceous period. Even before OAE2, during the late Cenomanian, tropical sea surface temperatures (SSTs) were very warm, about 27-29 °C. The onset of OAE2 was concurrent with a 4-5 °C rise in shelf sea temperatures. Mean tropical SSTs during OAE2 have been conservatively estimated to have been at least 30 °C, but may have reached as high as 36 °C. Minimum SSTs in mid-latitude oceans were >20 °C. This exceptional warmth persisted until the Turonian-Coniacian boundary.

One possible cause of this hothouse was sub-oceanic volcanism. During the middle of the Cretaceous period, the rate of crustal production reached a peak, which may have been related to the rifting of the newly formed Atlantic Ocean. It was also caused by the widespread melting of hot mantle plumes under the ocean crust, at the base of the lithosphere, which may have resulted in the thickening of the oceanic crust in the Pacific and Indian Oceans. The resulting volcanism would have sent large quantities of carbon dioxide into the atmosphere, leading to an increase in global temperatures. Several independent events related to large igneous provinces (LIPs) occurred around the time of OAE2. A multitude of LIPs were active during OAE2: the Madagascar, Caribbean, Gorgona, Ontong Java, and High Arctic LIPs. The abundance of LIPs at this time reflects a major overturning in mantle convection. Trace metals such as chromium (Cr), scandium (Sc), copper (Cu) and cobalt (Co) have been found at the Cenomanian-Turonian boundary, which suggests that an LIP could have been one of the main basic causes involved in the contribution of the event. The timing of the peak in trace metal concentration coincides with the middle of the anoxic event, suggesting that the effects of the LIPs may have occurred during the event, but may not have initiated the event. Other studies linked the lead (Pb) isotopes of OAE-2 to the Caribbean-Colombian and the Madagascar LIPs. An osmium isotope excursion coeval with OAE2 strongly suggests submarine volcanism as its cause; in the Pacific, an unradiogenic osmium spike began about 350 kyr before the onset of OAE2 and terminated around 240 kyr after OAE2's beginning; the osmium isotope data from a highly expanded OAE2 interval in southern Tibet show multiple osmium excursions with the most pronounced one lagging the onset of OAE2 by ≈50 kyr that was probably related to the ocean connectivity change at ≈94.5 Ma. Positive neodymium isotope excursions provide additional indications of pervasive volcanism as a cause of OAE2. Enrichments in zinc further bolster and reinforce the existence of extensive hydrothermal volcanism, as do extreme negative δ53Cr excursions. The absence of geographically widespread mercury (Hg) anomalies resulting from OAE2 has been suggested to be because of the limited dispersal range of this heavy metal by submarine volcanism. A modeling study performed in 2011 confirmed that it is possible that a LIP may have initiated the event, as the model revealed that the peak amount of carbon dioxide degassing from volcanic LIP degassing could have resulted in more than 90 percent global deep-ocean anoxia.

Later on, when anoxia became widespread, the production of nitrous oxide, a greenhouse gas about 1,000 times more potent than carbon dioxide, drastically increased because of elevated nitrification and denitrification rates. This powerful positive feedback mechanism is what may have enabled extremely hot temperatures to persist in spite of the supercharged organic carbon burial associated with anoxic events.

Plenus Cool Event
Large-scale organic carbon burial acted as a negative feedback loop that partially mitigated the warming effects of volcanic discharge of carbon dioxide, resulting in the Plenus Cool Event during the Metoicoceras geslinianum European ammonite biozone. Global average temperatures fell to around 4 °C lower than they were pre-OAE2. Equatorial SSTs dropped by 2.5–5.5 °C. This cooling event was insufficient at completely stopping the rise in global temperatures. This negative feedback was ultimately overridden, as global temperatures continued to shoot up in sync with continued volcanic release of carbon dioxide following the Plenus Cool Event, although this theory has been criticised and the warming after the Plenus Cool Event attributed to decreased silicate weathering instead.

Ocean acidification
Within the oceans, the emission of SO2, H2S, CO2, and halogens would have increased the acidity of the water, causing the dissolution of carbonate, and a further release of carbon dioxide. Evidence of ocean acidification can be gleaned from δ44/40Ca increases coeval with the extinction event, as well as coccolith malformation and dwarfism. Ocean acidification was exacerbated by a positive feedback loop of increased heterotrophic respiration in highly biologically productive waters, elevating seawater concentrations of carbon dioxide and further decreasing pH.

Anoxia and euxinia
When the volcanic activity declined, this run-away greenhouse effect would have likely been put into reverse. The increased CO2 content of the oceans could have increased organic productivity in the ocean surface waters. The consumption of this newly abundant organic life by aerobic bacteria would produce anoxia and mass extinction. An acceleration of the hydrological cycle induced by warmer global temperatures drove greater fluxes of nutrient runoff into the oceans, fuelling primary productivity. The global environmental disturbance that resulted in these conditions increased atmospheric and oceanic temperatures. Extreme hothouse conditions encouraged ocean stratification. Boundary sediments show an enrichment of trace elements, and contain elevated δ13C values. The positive δ13C isotope excursion found at the Cenomanian-Turonian boundary is one of the main carbon isotope events of the Mesozoic. It represents one of the largest disturbances in the global carbon cycle from the past 110 million years. This δ13C isotope excursion indicates a significant increase in the burial rate of organic carbon, indicating the widespread deposition and preservation of organic carbon-rich sediments and that the ocean was depleted of oxygen at the time. Depletion of manganese in sediments corresponding to OAE2 provides additional strong evidence of severe bottom water oxygen depletion. The resulting elevated levels of carbon burial would account for the black shale deposition in the ocean basins. The proto-North Atlantic in particular was a hotbed of carbon burial during OAE2 as it was in later, less severe anoxic events.

Sulphate reduction increased during OAE2, causing euxinia, a type of anoxia defined by sulphate reduction and hydrogen sulphide production, to occur during OAE2, as revealed by negative δ53Cr excursions, positive δ98Mo excursions, a low seawater molybdenum inventory, and molecular biomarkers of green sulfur bacteria.

OAE2 began on the southern margins of the proto-North Atlantic, from where anoxia spread across the rest of the proto-North Atlantic and then into the Western Interior Seaway (WIS) and the epicontinental seas of the Western Tethys. Anoxic waters spread rapidly throughout the WIS due to marine transgression and a powerful cyclonic circulation resulting from an imbalance between precipitation in the north and evaporation in the south. Anoxia was especially intense in the eastern North Sea, evidenced by its very positive δ13C values. Thanks to persistent upwelling, some marine regions, such as the South Atlantic, were able to remain partially oxygenated at least intermittently. Indeed, redox states of oceans vary geographically, bathymetrically and temporally during OAE2.

Milankovitch cycles
It has been hypothesised that the Cenomanian-Turonian boundary event occurred during a period of very low variability in Earth's insolation, which has been theorised to be the result of coincident nodes in all orbital parameters. Barring chaotic perturbations in Earth's and Mars' orbits, the simultaneous occurrence of nodes of orbital eccentricity, axial precession, and obliquity on Earth occurs approximately every 2.45 million years. Numerous other oceanic anoxic events occurred throughout the extremely warm greenhouse conditions of the Middle Cretaceous, and it has been suggested that these Middle Cretaceous ocean anoxic events occurred cyclically in accordance with orbital cycle patterns. The mid-Cenomanian Event (MCE), which occurred in the Rotalipora cushmani planktonic foraminifer biozone, has been argued to be another example supporting this hypothesis of regular oceanic anoxic events governed by Milankovitch cycles. The MCE took place approximately 2.4 million years before the Cenomanian-Turonian oceanic anoxic event, roughly at the time when an anoxic event would be expected to occur given such a cycle. Geochemical evidence from a sediment core in the Tarfaya Basin is indicative of the main positive carbon isotope excursion occurring during a prolonged eccentricity minimum. Carbon isotope shifts smaller in scale observed in this core likely reflected variability in obliquity. Ocean Drilling Program Site 1138 in the Kerguelen Plateau yields evidence of a 20,000 to 70,000 year periodicity in changes in sedimentation, suggesting that either obliquity or precession governed the large-scale burial of organic carbon. Within the positive carbon isotope excursion, short eccentricity scale carbon isotope variability is documented in a significantly expanded OAE2 interval from southern Tibet.

Enhanced phosphorus recycling
The phosphorus retention ability of seafloor sediments declined during OAE2, revealed by a decline in reactive phosphorus species within OAE2 sediments. The mineralisation of seafloor phosphorus into apatite was inhibited by the significantly lower pH of seawater and much warmer temperatures during the Cenomanian and Turonian compared to the present day, which meant that significantly more phosphorus was recycled back into ocean water after being deposited on the sea floor during this time. This would have intensified a positive feedback loop in which phosphorus is recycled faster into anoxic seawater compared to oxygen-rich water, which in turn fertilises the water, causes increased eutrophication, and further depletes the seawater of oxygen. The influx of volcanically erupted and chemically weathered sulphate into the ocean also inhibited phosphorus burial by increasing hydrogen sulphide production, which hinders the burial of phosphorus through sorption to iron oxyhydroxide phases. OAE2 may have occurred during a peak in a 5-6 Myr cycle governing phosphorus availability; at this and other peaks in this oscillation, an increase in chemical weathering would have increased the marine phosphorus inventory and sparked a positive feedback loop of increasing productivity, anoxia, and phosphorus recycling that was only ended by a negative feedback of increased atmospheric oxygenation and wildfire activity that decreased chemical weathering, a feedback which operated on a much longer timescale. Enhanced phosphorus recycling would have resulted in an abundance of nitrogen fixing bacteria, increasing the availability of yet another limiting nutrient and supercharging primary productivity through nitrogen fixation. The ratio of bioavailable nitrogen to bioavailable phosphorus, which is 16:1 in the present, fell precipitously as the ocean transitioned from being oxic and nitrate-dominated to anoxic and ammonium-dominated. A potent feedback loop of nitrogen fixation, productivity, deoxygenation, nitrogen removal, and phosphorus recycling was created. Bacterial hopanoids indicate populations of nitrogen fixing cyanobacteria were high during OAE2, providing a rich supply of nitrates and nitrites. Negative δ15N values reveal the dominance of ammonium through regenerative nutrient loops in the proto-North Atlantic.

Decreased sulphide oxidation
In the present day, sulphidic waters are generally prevented from spreading throughout the water column by the oxidation of sulphide with nitrate. However, during OAE2, the inventory of seawater nitrate was lower, meaning that chemolithoautotrophic oxidation of sulphides with nitrates was inefficient at preventing the spread of euxinia.

Sea level rise
A marine transgression in the latest Cenomanian resulted in an increase in average water depth, causing seawater to become less eutrophic in shallow, epicontinental seas. Turnovers in marine biota in such epicontinental seas have been suggested to be driven more so by changes in water depth rather than anoxia. Sea level rise also contributed to anoxia by transporting terrestrial plant matter from inundated lands seaward, providing an abundant source of sustenance for eutrophicating microorganisms.

Geological effects

Phosphate deposition
A phosphogenic event occurred in the Bohemian Cretaceous Basin during the peak of oceanic anoxia. Phosphorus liberation in the pore water environment, several centimetres below the interface between seafloor sediments and the water column, enabled the precipitation of phosphate through biological mediation by microorganisms.

Increase in weathering
Strontium and calcium isotope ratios both indicate that silicate weathering increased over the course of OAE2. Because of its effectiveness as a carbon sink on geologic timescales, the uptick in sequestration of carbon dioxide by the lithosphere may have helped to stabilise global temperatures after global temperatures soared. Particularly so at high latitudes, where the increase in weatherability was very pronounced.

Biotic effects

Changes in oceanic biodiversity and its implications
The event brought about the extinction of the pliosaurs, and most ichthyosaurs. Coracoids of Maastrichtian age were once interpreted by some authors as belonging to ichthyosaurs, but these have since been interpreted as plesiosaur elements instead.

Although the cause is still uncertain, the result starved the Earth's oceans of oxygen for nearly half a million years, causing the extinction of approximately 27 percent of marine invertebrates, including certain planktic and benthic foraminifera, mollusks, bivalves, dinoflagellates and calcareous nannofossils. Planktonic foraminifera that dwelt in deeper waters were especially hard hit by the expansion of oxygen minimum zones. The alterations in diversity of various marine invertebrate species such as calcareous nannofossils are reflective and characteristic of oligotrophy and ocean warmth in an environment with short spikes of productivity followed by long periods of low fertility. A study performed in the Cenomanian-Turonian boundary of Wunstorf, Germany, reveal the uncharacteristic dominance of a calcareous nannofossil species, Watznaueria, present during the event. Unlike the Biscutum species, which prefer mesotrophic conditions and were generally the dominant species before and after the C/T boundary event; Watznaueria species prefer warm, oligotrophic conditions. In the Ohaba-Ponor section in Romania, the presence of Watznaueria barnesae indicates warm conditions, while the abundances of Biscutum constans, Zeugrhabdotus erectus, and Eprolithus floralis peak during cool intervals. Sites in Colorado, England, France, and Sicily show an inverse relationship between atmospheric carbon dioxide levels and the size of calcareous nannoplankton. In Whadi El Ghaib, a site in Sinai, Egypt, the foraminiferal community during OAE2 was low in diversity and dominated by taxa that were extremely tolerant of low salinity, anoxic water. Radiolarians also suffered heavy losses in OAE2, one of their highest diversity losses in the Cretaceous. Rudist bivalves suffered high extinction rates combined with low origination rates during OAE2.

The diversity of trace fossils sharply plummeted during the beginning of the Cenomanian-Turonian boundary event. The recovery interval after the anoxic event's conclusion features an abundance of Planolites and is characterised overall by a high degree of bioturbation.

At the time, there were also peak abundances of the green algal groups Botryococcus and prasinophytes, coincident with pelagic sedimentation. The abundances of these algal groups are strongly related to the increase of both the oxygen deficiency in the water column and the total content of organic carbon. The evidence from these algal groups suggest that there were episodes of halocline stratification of the water column during the time. A species of freshwater dinocyst—Bosedinia—was also found in the rocks dated to the time and these suggest that the oceans had reduced salinity.

Changes in terrestrial biodiversity
No major change in terrestrial ecosystems is known to have been synchronous with the marine transgression associated with OAE2, although the loss of freshwater floodplain habitat has been speculated to have possibly resulted in the demise of some freshwater taxa. In fossiliferous rocks in southwestern Utah, a local extirpation of some metatherians and brackish water vertebrates is associated with the later marine regression following OAE2 in the Turonian. Whatever the nature and magnitude of terrestrial extinctions at or near the Cenomanian-Turonian boundary was, it was most likely caused mainly by other factors than eustatic sea level fluctuations. The effect of the ecological crisis on terrestrial plants has been concluded to have been inconsequential, in contrast to extinction events driven by terrestrial large igneous provinces.

See also
 Biodiversity of the Cenomanian and Turonian
 Cenomanian life
 Turonian life
 Cenomanian extinctions
 Turonian extinctions
 Extinction event
 Timeline of extinctions in the Holocene
 Toarcian turnover
 Cretaceous–Paleogene extinction event

References

Further reading

Extinction events
 Ceno

Paleoclimatology

Anoxic events

Cenomanian-Turonian boundary event


The modern pentathlon at the 1976 Summer Olympics was represented by two events (both for men): Individual competition and Team competition. As usual in Olympic modern pentathlon, one competition was held and each competitor's score was included to the Individual competition event results table and was also added to his teammates' scores to be included to the Team competition event results table. This competition consisted of 5 disciplines:

Equestrian, held on July 18 at Bromont.
Fencing, held on July 19 at Université de Montréal.
Shooting, held on July 20 at L'Acadie.
Swimming, held on July 21 at Montreal Olympic Pool
Cross-country, held on July 22 at Olympic Stadium and Maisonneuve Park.

Boris Onischenko of the Soviet Union was ejected from the competition during the fencing event after it was discovered he had wired his épée with a concealed push button circuit breaker that enabled him to register a hit at any time. Onischenko's results were deleted from the records, and he was spirited away from the Olympic Village almost immediately, never competing in events outside the USSR again.

The other Soviet team members, Pavel Lednev and Boris Mosolov, were allowed to continue individually, but as three athletes are required to compete in a team event, it was ruled that their results would receive no score in the team competition.

Participating nations
A total of 47 athletes from 17 nations competed at the Montreal Games:

Medal summary

Medal table

References

External links
Official Olympic Report

1976 Summer Olympics events

Modern pentathlon at the 1976 Summer Olympics


A factsheet, fact sheet or fact file is a single page document containing essential information about a product, substance, service or other topic. Factsheets are frequently used to provide information to an end user, consumer or member of the public in concise, simple language. They generally contain key safety points, operating instructions or basic information about a topic depending on the purpose of the fact sheet.

Typical contents
Factsheets frequently make use of elements such as lists, tables and diagrams to convey meaning quickly and effectively. The language and content of a factsheet depend on its target audience; a factsheet aimed at professional engineers may use more technical language than one aimed at an end-user.

History
Factsheets were traditionally printed and physically distributed, often included in the packaging of a product. Many manufacturers now provide digital factsheets as well as or instead of paper-and-ink documents.

Examples

The World Health Organization provides fact sheets on wide range of health issues
 The US National Aeronautics and Space Administration provides planetary fact sheets.
 The US conservation organization Defenders of Wildlife provides fact sheets about animals.
 The World Factbook, a collection from the US Central Intelligence Agency of tabular factsheets on various countries.
 The Federal Republic of Germany has published a fact sheet on the unique dual vocational training system.

See also
 One sheet
 Executive summary
 Infobox
 Infographic
 Press release
 Public relations

References

Data publishing
Information
Technical communication
News media
Publishing

Fact sheet


Frances Aparicio is the author of Listening to Salsa: Gender, Latin Popular Music, and Puerto Rican Cultures (). She is also the co-author of Musical Migrations: Transnationalism and Cultural Hybridity in Latin/o America, Volume I and Tropicalizations: Transcultural Representations of Latinidad (Re-Encounters with Colonialism). She is the editor of several books including Latino Voices. She has been a professor at Northwestern University and University of Illinois at Chicago, where she directed the Latina/Latino Studies Program.

She was born Frances Rivera in Puerto Rico on December 11, 1955. She moved to the United States to earn her bachelor's at Indiana University Bloomington. She earned a Ph.D. at Harvard University. She is an editorial advisory board member of Chasqui, a Latin American and Latinx literature, philosophy, and arts journal.

References

1955 births
Living people
University of Illinois Chicago faculty
Indiana University Bloomington alumni
Harvard University alumni
American writers about music
Women writers about music
American women non-fiction writers

Frances Aparicio


Pinguicula primuliflora ( /ˌpɪˈŋgwɪkjələ ˌpɹɪmjʊləˈfloːɹə/ ), commonly known as the southern butterwort or primrose butterwort, is a species of carnivorous plant belonging to the genus Pinguicula. It is native to the southeastern United States. The typical variety forms a white flower in blooming. Like other butterworts, it has sticky adhesive leaves which attract, capture and digest arthropod prey in order to supply the plant with nutrients such as nitrogen not found in the nutrient poor, acidic soil that it grows in. Its name derives from the fact it is usually the first one to flower in the spring.

Roots

Like all Pinguicula, the roots are undeveloped, and are mainly used to absorb water and anchor the plant, nutrients are absorbed through carnivory.

Carnivory

Pinguicula primuliflora, like all members of the family Lentibulariaceae, is carnivorous. Their leaves are covered with tiny hairs which secrete a mucilaginous liquid. This gives the leaves a wet appearance and is believed to attract insects in search of water. As soon as an insect lands on the leaves, it becomes ensnared in the mucilage; as it struggles, it gathers more of the liquid on it. The plant responds by secreting digestive enzymes that dissolve and digest the insides of the prey, creating a nutrient soup which the plant then absorbs. The leaves of P. primuliflora are green.

Flowers

Pinguicula primuliflora has 5-petaled zygomorphic flowers. The plant is self-fertile, but must be pollinated to be fertilized.

Cultivation

Pinguicula primuliflora is an ideal beginners first butterwort in cultivation. It is typically easy to grow, and does not require high humidity, nor extremely intense lighting to flower and create sticky, carnivorous leaves. It can be propagated by selfing, or, more effectively, through cross pollination with another plant. P. primuliflora has known to be quite the weed in cultivation, and it is not unusual to find many shoots coming out from the plant, which can eventually take over the pot and may need maintenance. P. primuliflora requires the basics of any carnivorous plant; it needs poor, acidic soil, such as 50/50 peat moss and perlite or horticultural sand mix, or pure sphagnum peat moss mix, with no potting soil or fertilizer. P. primuliflora, along with some other butterworts, can be grown in a tray of standing water to increase humidity and maintain soil moisture.

Distribution and habitat

Pinguicula primuliflora is native to the southeastern United States.  Specifically, they are commonly found between the southern east of Mississippi, to the north west of Florida.  They are in Zone 8 of the US. They can handle for short periods down to 20F or -9C for brief periods of time during their dormancy, which typically lasts 3–4 months.

References

External links
Barry Rice's Carnivorous Plant FAQ

Carnivorous plants of North America
primuliflora
Endemic flora of the United States
Flora of the Southeastern United States
Plants described in 1957
Flora without expected TNC conservation status

Pinguicula primuliflora


Ivica Pajer (9 September 1934 – 17 August 2006) was a Yugoslavian-born Croatian actor. He is perhaps best known for portraying  David before he became a king in the 1960 film David and Goliath starring Orson Welles of which Pajer is credited as Ivo Payer. Pajer also had one of the major roles in The Road a Year Long, a 1958 Academy Award-nominated film directed by Giuseppe De Santis.

Filmography

References

Croatian male film actors
1934 births
2006 deaths
Yugoslav male film actors

Ivica Pajer


Freedomland is a 2006 American crime drama mystery film directed by Joe Roth and starring Samuel L. Jackson, Julianne Moore, Edie Falco, Ron Eldard, William Forsythe, Aunjanue Ellis, and Anthony Mackie. It is based on Richard Price's 1998 novel of the same name, which touches on themes of covert racism. The film grossed $14.7 million against a $30 million budget.  The Rotten Tomatoes critical consensus calls it "poorly directed and overacted".

Plot

Brenda walks through a predominantly African American housing project and enters an emergency room in a daze, apparently in shock and with cut and bleeding hands. Police detective Lorenzo Council is sent to take a statement from her, who says that her car has been stolen. When Lorenzo gets there, she reveals that her young son, Cody, was in the back seat of the car. The police frantically begin searching for him.

Brenda's brother, Danny, a police officer in a neighboring town, calls a massive police presence in to search the housing project for clues. This angers the residents who protest their innocence. Lorenzo begins to suspect that Brenda is holding back details from him and pressures her to tell the truth. She insists that she has told the truth and would never harm her son. With a sketch artist she produces a picture of the man she says stole her car. Danny's white coworkers arrest a man from the housing project who they think matches the picture. Danny flies into a rage and beats him.

Desperate to find Cody, Lorenzo enlists the aid of a volunteer group which helps search for missing children. He suggests that they search Freedomland, an abandoned foundling hospital nearby. As they search, the group's leader Karen Collucci talks with Brenda. She had lost her own son years before and convinces Brenda to admit that Cody is dead. She leads them to a nearby park where they find Cody's body in a shallow grave, covered with heavy rocks.

Lorenzo realizes that Brenda could not have moved the rocks herself. Under interrogation Brenda admits to having been engaged in an affair with a man named Billy who lived in the projects. She would give Cody cough syrup so that he would fall asleep and she could visit Billy.

On the night in question, before Brenda had gone out, Cody had begged her not to leave and insisted she'd regret it. Desperate, believing it would be the last time she'd get to meet up with Billy, she went anyway. When Brenda had returned she'd found Cody dead, having drunk the whole bottle of cough syrup. Billy helped her bury his body.

When the police go to arrest Billy, they are confronted by residents angry over previous unfounded police harassment and a riot erupts. Brenda is charged with criminal neglect, and Lorenzo promises to visit her in jail.

Cast

Production
Shooting took place mostly in Yonkers, New York.

Release

Home media
The film was released on DVD on May 30, 2006 with no special features. The film debuted on the Blu-ray format for the first time on November 6, 2012 by Mill Creek Entertainment. It was included in a double feature with the horror film The Messengers (2007).

Reception

Box office
The film grossed $14.7 million against its $30 million budget.

Critical reception
On Rotten Tomatoes, the film has an approval rating of 24% based on 148 reviews. The consensus states: "Poorly directed and overacted, Freedomland attempts to address sensitive race and class issues but its overzealousness misses the mark." On Metacritic, it has a score of 43 out of 100 based on 35 reviews. Audiences surveyed by CinemaScore gave the film a grade C+ on scale of A to F.

Roger Ebert gave the film an overall negative review, and awarded the film 2 out of 4 stars, writing: "Freedomland assembles the elements for a superior thriller, but were the instructions lost when the box was opened? It begins with a compelling story about a woman whose car is hijacked with her 4-year-old son inside. It adds racial tension, and the bulldog detective work of a veteran police detective. Then, it flies to pieces with unmotivated scenes, inexplicable dialogue, and sudden conclusions which may be correct but arrive from nowhere. The film seems edited none too wisely from a longer version that made more sense."

Sheri Linden of The Hollywood Reporter wrote: "The film is, above all, a moving portrait of hurting souls, brought to life in compelling performances."
Brian Lowry of Variety wrote: "Despite a few raw moments, pic feels like a Lifetime movie with a marquee cast."

In a more positive review, James Berardinelli awarded the film 3 out of 4 stars, writing: "The thing that makes Freedomland riveting is the way in which its tale of human tragedy unfolds. Although it begins by looking like a big screen episode of CSI, it develops into something more sublime and disturbing. This isn't a mystery in the conventional sense, but it's about secrets hidden and revealed, and the corrosive power of guilt. Even as Council probes into the dark recesses of Brenda's psyche, he seeks to exorcise his own demons. The two form an unlikely connection, the nature of which cannot be revealed without spoiling the ending. But don't expect any last-minute twists or turns. The movie doesn't employ sensationalist tactics to enhance its potency."

References

External links

2006 films
2006 crime drama films
2006 crime thriller films
2000s American films
2000s English-language films
American crime thriller films
Columbia Pictures films
Films about children
Films about grieving
Films about missing people
Films about race and ethnicity
Films based on American novels
Films based on crime novels
Films directed by Joe Roth
Films produced by Scott Rudin
Films scored by James Newton Howard
Films with screenplays by Richard Price (writer)
Revolution Studios films

Freedomland (film)