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Physical Cosmology

Physical Cosmology
Universe · Big Bang Age of the universe Timeline of the Big Bang... Ultimate fate of the Universe Image File history File links Download high resolution version (2198x1274, 1278 KB)WMAP map of CMB anisotropy, from NASA.gov File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Physical cosmology, as a branch of astrophysics, is the study of the large-scale structure of the universe and is concerned with fundamental questions about its formation and evolution. ... The Universe is defined as the summation of all particles and energy that exist and the space-time in which all events occur. ... According to the Big Bang model, the universe emerged from an extremely dense and hot state. ... The age of the universe, according to the Big Bang theory, is the time elapsed between the Big Bang and the present day. ... A graphical timeline is available here: Graphical timeline of the Big Bang This timeline of the Big Bang describes the events that have occurred and will occur according to the scientific theory of the Big Bang, using the cosmological time parameter of comoving coordinates. ... The ultimate fate of the universe is a topic in physical cosmology. ...
Early universe
Inflation · Nucleosynthesis Cosmic gravitational waves Cosmic microwave background In cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang. ... This article or section is in need of attention from an expert on the subject. ... In cosmology, the cosmic microwave background radiation (most often abbreviated CMB but occasionally CMBR, CBR or MBR, also referred as relic radiation) is a form of electromagnetic radiation discovered in 1965 that fills the entire universe. ...
Expanding universe
Redshift · Hubble's law Metric expansion of space Friedmann equations · FLRW metric Redshift of spectral lines in the optical spectrum of a supercluster of distant galaxies (right), as compared with that of the Sun (left). ... Hubbles law is the statement in physical cosmology that the redshift in light coming from distant galaxies is proportional to their distance. ... The metric expansion of space is a key part of sciences current understanding of the universe, whereby space itself is described by a metric which changes over time. ... The Friedmann equations relate various cosmological parameters within the context of general relativity. ... // The Friedmann-LemaÃ®tre-Robertson-Walker (FLRW) metric is an exact solution of the Einstein field equations of general relativity and which describes a homogeneous, isotropic expanding/contracting universe. ...
Structure formation
Shape of the universe Structure formation Galaxy formation Large-scale structure The shape of the Universe is an informal name for a subject of investigation within physical cosmology. ... It has been suggested that this article or section be merged into Large-scale structure of the cosmos. ... In astrophysics, the questions of galaxy formation and evolution are: How, from a homogeneous universe, did we obtain the very heterogeneous one we live in? How did galaxies form? How do galaxies change over time? A spectacular head-on collision between two galaxies is seen in this NASA Hubble Space... Astronomy and cosmology examine the universe to understand the large-scale structure of the cosmos. ...
Components
Lambda-CDM model Dark energy · Dark matter A pie chart indicating the proportional composition of different energy-density components of the universe. ... In physical cosmology, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. ... In astrophysics and cosmology, dark matter refers to hypothetical matter of unknown composition that does not emit or reflect enough electromagnetic radiation to be observed directly, but whose presence can be inferred from gravitational effects on visible matter. ...
History
Timeline of cosmology... This lists a timeline of cosmological theories and discoveries. ...
Cosmology experiments
Observational cosmology 2dF · SDSS CoBE · BOOMERanG · WMAP Observational cosmology is the study of the structure, the evolution and the origin of the universe through observation, using instruments such as telescopes and cosmic ray detectors. ... In astronomy, the 2dF Galaxy Redshift Survey (Two-degree-Field Galaxy Redshift Gurvey), or 2dFGRS is a redshift survey conducted by the Anglo-Australian Observatory in the 1990s. ... SDSS Logo The Sloan Digital Sky Survey or SDSS is a major multi-filter imaging and spectroscopic redshift survey using a dedicated 2. ... The Cosmic Background Explorer (COBE), also referred to as Explorer 66, was the first satellite built dedicated to cosmology. ... The Telescope being readied for launch The BOOMERanG experiment (Balloon Observations Of Millimetric Extragalactic Radiation and Geophysics) measured the cosmic microwave background radiation of a part of the sky during three sub-orbital (high altitude) balloon flights. ... Artist depiction of the WMAP satellite at the L2 point The Wilkinson Microwave Anisotropy Probe (WMAP) is a NASA satellite whose mission is to survey the sky to measure the temperature of the radiant heat left over from the Big Bang. ...
Scientists
Einstein · Friedman · Lemaître Hubble · Penzias · Wilson Gamow · Dicke · Zel'dovich Mather · Smoot · others Albert Einstein ( ) (March 14, 1879 â€“ April 18, 1955) was a German-born theoretical physicist who is best known for his theory of relativity and specifically mass-energy equivalence, . He was awarded the 1921 Nobel Prize in Physics for his services to Theoretical Physics, and especially for his discovery of the... Alexander Alexandrovich Friedman or Friedmann (ÐÐ»ÐµÐºÑÐ°Ð½Ð´Ñ€ ÐÐ»ÐµÐºÑÐ°Ð½Ð´Ñ€Ð¾Ð²Ð¸Ñ‡ Ð¤Ñ€Ð¸Ð´Ð¼Ð°Ð½) (June 16, 1888 â€“ September 16, 1925) was a Russian cosmologist and mathematician. ... Father Georges-Henri LemaÃ®tre (July 17, 1894 â€“ June 20, 1966) was a Belgian Roman Catholic priest, honorary prelate, professor of physics and astronomer. ... Edwin Powell Hubble (November 29, 1889 â€“ September 28, 1953) was an American astronomer. ... Arno Allan Penzias (born April 26, 1933) is an American physicist and winner of the 1978 Nobel Prize in physics. ... Robert Woodrow Wilson Robert Woodrow Wilson (born January 10, 1936) is an American physicist. ... George Gamow (pronounced GAM-off) (March 4, 1904 â€“ August 19, 1968) , born Georgiy Antonovich Gamov (Ð“ÐµÐ¾Ñ€Ð³Ð¸Ð¹ ÐÐ½Ñ‚Ð¾Ð½Ð¾Ð²Ð¸Ñ‡ Ð“Ð°Ð¼Ð¾Ð²) was a Ukrainian born physicist and cosmologist. ... Robert Henry Dicke (May 6, 1916 â€“ March 4, 1997) was an American experimental physicist, who made important contributions to the fields of astrophysics, atomic physics, cosmology and gravity. ... Yakov Borisovich Zeldovich (Russian:Ð¯ÐºÐ¾Ð² Ð‘Ð¾Ñ€Ð¸ÑÐ¾Ð²Ð¸Ñ‡ Ð—ÐµÐ»ÑŒÐ´Ð¾Ð²Ð¸Ñ‡) (March 8, 1914 â€“ December 2, 1987) was a prolific Soviet physicist. ... John Cromwell Mather (b. ... George Fitzgerald Smoot III (born February 20, 1945) is an American astrophysicist and cosmologist awarded the 2006 Nobel Prize in Physics with John C. Mather for their discovery of the black body form and anisotropy of the cosmic microwave background radiation. This work helped cement the big-bang theory of... This is a partial list of persons who have made major contributions to the development of standard mainstream Cosmology. ...
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This article is about the cosmological theory. For the candy bar, see Nestlé Crunch.

In physical cosmology, the Big Crunch is the hypothesis that the universe will collapse upon itself after its expansion eventually stops — a counterpart to the Big Bang. This hypothesis is the subject of much heated discussion. Nestle Crunch wrapped Nestle Crunch NestlÃ© Crunch is the name of a candy bar made of milk chocolate with crisped rice mixed in, produced by NestlÃ©. NestlÃ© also produces other Crunch products: NestlÃ© Crunch Pieces (also known as Buncha Crunch), are candy pieces made of milk chocolate with crisped rice... Physical cosmology, as a branch of astrophysics, is the study of the large-scale structure of the universe and is concerned with fundamental questions about its formation and evolution. ... Look up Hypothesis in Wiktionary, the free dictionary. ... The Universe is defined as the summation of all particles and energy that exist and the space-time in which all events occur. ... The metric expansion of space is a key part of sciences current understanding of the universe, whereby space itself is described by a metric which changes over time. ... According to the Big Bang model, the universe emerged from an extremely dense and hot state. ...

Overview

If the gravitational attraction of all the matter within the observable horizon were high enough, the expansion of the universe would slow, and then reverse eventually. The universe would then contract, with about the same duration as the expansion. Eventually, all matter and energy would be compressed back into a gravitational singularity. Gravity is a force of attraction that acts between bodies that have mass. ... This article or section does not cite any references or sources. ... A gravitational singularity (sometimes spacetime singularity) is, approximately, a place where quantities which are used to measure the gravitational field become infinite. ...

Lensing due to gravity.

However, recent experimental evidence (namely the observation of distant supernovae as standard candles, and the well-resolved mapping of the cosmic microwave background) has—to considerable surprise—shown that the expansion of the universe is not being slowed down by gravity, but instead, accelerating, suggesting that the universe will not end with a Big Crunch, but will instead expand forever. Although some scientists have contested this theory,[1] most cosmologists have considered the evidence of an accelerating universe to be conclusive since 2002. Gravitational lensing. ... Gravitational lensing. ... Remnant of Keplers Supernova, SN 1604. ... A standard candle is an astronomical object that has a known luminosity. ... WMAP image of the CMB anisotropy,Cosmic microwave background radiation(June 2003) The cosmic microwave background radiation (CMB) is a form of electromagnetic radiation that fills the whole of the universe. ... The Accelerating universe is the idea that our universe is undergoing accelerated expansion: distant objects are receding from our galaxy with speeds that increase over time. ... For album titles with the same name, see 2002 (album). ...

In the framework of the field equations of the General Theory of Relativity, the simplest model of an accelerating expansion corresponds to a positive value of the cosmological constant, which can be attributed to the quantum vacuum itself exerting a force that repels gravitationally on large scales. More generally, the accelerating expansion is attributed to dark energy, which could be the cosmological constant, or a dynamical field with negative "pressure", leading to an effective cosmological constant that could be time-varying. In such cases, it is theoretically possible that the cosmological "constant" need not remain positive, leaving open the possibility of a Big Crunch as the ultimate fate of the universe. A Big Crunch is also still theoretically possible if Einstein's theory of general relativity were found not to apply on large scales. The current evidence neither favors nor rules out dark energy, or modifications of general relativity, of a form that could halt or reverse an eternal expansion; it does, however set lower bounds on the duration collapse (approximately 42 billion years from now, or more than 24 billion years at the 95% confidence level, according to one group led by Andrei Linde). General relativity (GR) or general relativity theory (GRT) is the theory of gravitation published by Albert Einstein in 1915. ... The cosmological constant (usually denoted by the Greek capital letter lambda: Î›) was proposed by Albert Einstein as a modification of his original theory of general relativity to achieve a stationary universe. ... In physical cosmology, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. ... The ultimate fate of the universe is a topic in physical cosmology. ... In statistics, confidence intervals are the most prevalent form of interval estimation. ... Andrei Linde is an American physicist and professor of Physics at Californias Stanford University. ...

External links

"Cosmic doomsday delayed" (news@nature.com)
"Current Observational Constraints on Cosmic Doomsday" (Wang, Kratochvil, Linde, and Shmakova)
"How to destroy the earth @ Things of Interest"

v • d • e Doomsday

Doomsday

Topics: Doomsday Argument · Risks to civilization, humans and planet Earth · Human extinction · Ultimate fate of the universe · Big Rip · Big Freeze · Big Crunch · Heat death of the universe · Apocalypse · End of planet Earth · Apocalyptic and post-apocalyptic fiction Look up doomsday in Wiktionary, the free dictionary. ... Look up doomsday in Wiktionary, the free dictionary. ... The Doomsday argument (DA) is a probabilistic argument that claims to predict the future lifetime of the human race given only an estimate of the total number of humans born so far. ... Risks to civilization, humans and planet Earth are existential risks that would imperil humankind as a whole and/or have major adverse consequences for the course of human civilization, human extinction or even the end of planet Earth. ... Human extinction would be the extinction of the human species, Homo sapiens. ... The ultimate fate of the universe is a topic in physical cosmology. ... The Big Rip is a cosmological hypothesis about the ultimate fate of the Universe, in which the elements of the universe, from galaxies to atoms, are progressively torn apart by the expansion of the universe. ... The Big Freeze is a scenario in which the universe simply becomes too cold to sustain life due to continued expansion. ... The heat death is a possible final state of the universe, in which it has run down to a state of no free energy to sustain motion or life. ... Look up Apocalypse in Wiktionary, the free dictionary. ... The end of planet Earth refers to when the Earth is theorized to either completely cease to exist as a planet or become uninhabitable for life. ... It has been suggested that Post-holocaust be merged into this article or section. ...

Categories: Physical cosmology | Eschatology

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