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'{{For|a timeline of the cosmos (or universe)|Chronology of the universe}} {{Cosmology|history}} This '''timeline of cosmological theories''' and discoveries is a [[Chronology|chronological]] record of the development of humanity's understanding of the [[cosmos]] over the last two-plus millennia. Modern [[Cosmology|cosmological]] ideas follijjgfjhdj jcjnvfkjvfibchb ow the development of the [[science|scientific discipline]] of [[physical cosmology]].,bbfjnbbcyhfbcbbkncfkbh hbv jjh uhrkhfdk ==Pre-1900== * ca. '''16th century BCE'''&nbsp;— Mesopotamian cosmology has a [[Flat Earth|flat, circular Earth]] enclosed in a [[cosmic ocean]].<ref>Horowitz (1998), p.xii</ref> * ca. '''12th century BCE'''&nbsp;— The ''[[Rigveda]]'' has some cosmological hymns, particularly in the late [[Mandala 10|book 10]], notably the [[Nasadiya Sukta]] which describes the origin of the [[universe]], originating from the [[monistic]] ''[[Hiranyagarbha]]'' or "Golden Egg". * '''6th century BCE'''&nbsp;— The [[Babylonian world map]] shows the Earth surrounded by the cosmic ocean, with seven islands arranged around it so as to form a seven-pointed star. Contemporary [[Biblical cosmology]] reflects the same view of a flat, circular Earth swimming on water and overarched by the solid vault of the [[firmament]] to which are fastened the stars. * '''4th century BCE'''&nbsp;— [[Aristotle]] proposes an [[Geocentric model|Earth-centered universe]] in which the Earth is stationary and the [[cosmos]] (or universe) is finite in extent but infinite in time * '''4th century BCE'''&nbsp;— [[De Mundo]] - Five elements, situated in spheres in five regions, the less being in each case surrounded by the greater — namely, earth surrounded by water, water by air, air by fire, and fire by ether — make up the whole Universe.<ref name=1908DeMundo>{{cite book|url=https://archive.org/details/demundoarisrich|title=De Mundo|year=1914|author=Aristotle; Forster, E. S. (Edward Seymour), 1879-1950; Dobson, J. F. (John Frederic), 1875-1947|page=2|location=Oxford |publisher=The Clarendon Press}}</ref> * '''3rd century BCE'''&nbsp;— [[Aristarchus of Samos]] proposes a [[Heliocentric model|Sun-centered universe]] * '''3rd century BCE'''&nbsp;— [[Archimedes]] in his essay [[The Sand Reckoner]], estimates the diameter of the cosmos to be the equivalent in [[Stadion (unit of length)|stadia]] of what we call two [[light year]]s * '''2nd century BCE'''&nbsp;— [[Seleucus of Seleucia]] elaborates on Aristarchus' heliocentric universe, using the phenomenon of [[tide]]s to explain heliocentrism * '''2nd century CE'''&nbsp;— [[Ptolemy]] proposes an Earth-centered universe, with the [[Classical planet|Sun, moon, and visible planets]] revolving around the Earth * '''5th-11th centuries'''&nbsp;— Several astronomers propose a Sun-centered universe, including [[Aryabhata]], [[Ja'far ibn Muhammad Abu Ma'shar al-Balkhi|Albumasar]]<ref name="WDL">{{cite web |url = http://www.wdl.org/en/item/2998/ |title = Introduction to Astronomy, Containing the Eight Divided Books of Abu Ma'shar Abalachus |website = [[World Digital Library]] |date = 1506 |accessdate = 2013-07-16 }}</ref> and [[Al-Sijzi]] * '''6th century'''&nbsp;— [[John Philoponus]] proposes a universe that is finite in [[time]] and argues against the ancient Greek notion of an infinite universe * Revealed in the 6th century, the [[Qur'an]] mentions Chapter 21: Verse 30 - "Have those who disbelieved not considered that the heavens and the earth were a joined entity, and We separated them ... " *ca. '''8th century'''&nbsp;— Puranic [[Hindu cosmology]], in which the [[Universe]] goes through repeated cycles of creation, destruction and rebirth, with each cycle lasting 4.32 billion years. * '''9th-12th centuries'''&nbsp;— [[Al-Kindi]] (Alkindus), [[Saadia Gaon]] (Saadia ben Joseph) and [[Al-Ghazali]] (Algazel) support a universe that has a finite past and develop two logical arguments against the notion of an infinite past, one of which is later adopted by [[Immanuel Kant]] * '''964'''&nbsp;— [[Abd al-Rahman al-Sufi]] (Azophi), a [[Islamic astronomy|Persian astronomer]], makes the first recorded observations of the [[Andromeda Galaxy]] and the [[Large Magellanic Cloud]], the first galaxies other than the Milky Way to be observed from Earth, in his ''[[Book of Fixed Stars]]'' * '''12th century'''&nbsp;— [[Fakhr al-Din al-Razi]] discusses [[Islamic cosmology]], rejects Aristotle's idea of an Earth-centered universe, and, in the context of his commentary on the [[Qur'an]]ic verse, "All praise belongs to God, Lord of the Worlds," proposes that the universe has more than "a thousand thousand worlds beyond this world such that each one of those worlds be bigger and more massive than this world as well as having the like of what this world has."<ref>{{citation|title=Fakhr Al-Din Al-Razi on Physics and the Nature of the Physical World: A Preliminary Survey |author=Adi Setia |journal=Islam & Science |volume=2 |date=2004 |url=http://findarticles.com/p/articles/mi_m0QYQ/is_2_2/ai_n9532826/ |archive-url=https://archive.is/20120710164222/http://findarticles.com/p/articles/mi_m0QYQ/is_2_2/ai_n9532826/ |dead-url=yes |archive-date=2012-07-10 |accessdate=2010-03-02 }}</ref> He argued that there exists an infinite [[outer space]] beyond the known world,<ref name=Iskenderoglu>{{citation|title=Fakhr al-Dīn al-Rāzī and Thomas Aquinas on the question of the eternity of the world|author=Muammer İskenderoğlu|publisher=[[Brill Publishers]]|date=2002|isbn=978-90-04-12480-6|page=79}}</ref> and that there could be an infinite number of universes.<ref>{{citation|title=al-Razi, Fakhr al-Din (1149-1209)|work=[[Routledge Encyclopedia of Philosophy]]|author=John Cooper|date=1998|publisher=[[Routledge]]|url=http://www.muslimphilosophy.com/ip/rep/H044.htm|accessdate=2010-03-07}}</ref> * '''13th century'''&nbsp;— [[Nasīr al-Dīn al-Tūsī]] provides the first [[Empirical research|empirical evidence]] for the [[Earth's rotation]] on its axis * '''15th century'''&nbsp;— [[Ali Qushji]] provides empirical evidence for the Earth's rotation on its axis and rejects the stationary Earth theories of Aristotle and Ptolemy * '''15th-16th centuries'''&nbsp;— [[Nilakantha Somayaji]] and [[Tycho Brahe]] propose a universe in which the planets orbit the Sun and the Sun orbits the Earth, known as the [[Tychonic system]] * '''1543'''&nbsp;— [[Nicolaus Copernicus]] publishes his [[Copernican heliocentrism|heliocentric universe]] in his ''[[De revolutionibus orbium coelestium]]'' * '''1576'''&nbsp;— [[Thomas Digges]] modifies the [[Copernican heliocentrism|Copernican system]] by removing its outer edge and replacing the edge with a [[star]]-filled unbounded space * '''1584'''&nbsp;— [[Giordano Bruno]] proposes a non-hierarchical cosmology, wherein the Copernican [[solar system]] is not the center of the universe, but rather, a relatively insignificant [[star system]], amongst an infinite multitude of others * '''1610'''&nbsp;— [[Johannes Kepler]] uses the dark night sky to argue for a finite universe * '''1687'''&nbsp;— Sir Isaac Newton's [[Physical law|laws]] describe large-scale motion throughout the universe * '''1720'''&nbsp;— [[Edmund Halley]] puts forth an early form of [[Olbers' paradox]] * '''1729'''&nbsp;- [[James Bradley]] discovers the [[aberration of light]], due to the Earth's motion around the Sun. * '''1744'''&nbsp;— [[Jean-Philippe de Cheseaux]] puts forth an early form of Olbers' paradox * '''1755'''&nbsp;— [[Immanuel Kant]] asserts that the [[nebulae]] are really [[galaxy|galaxies]] separate from, independent of, and outside the [[Milky Way Galaxy]]; he calls them ''[[island universe]]s''. * '''1785'''&nbsp;— [[William Herschel]] proposes the theory that our Sun is at or near the [[Galactocentrism|center of the galaxy]]. * '''1791'''&nbsp;— [[Erasmus Darwin]] pens the first description of a cyclical expanding and contracting universe in his poem ''[[The Botanic Garden|The Economy of Vegetation]]'' * '''1826'''&nbsp;— [[Heinrich Wilhelm Olbers]] puts forth [[Olbers' paradox]] * '''1837'''&nbsp;- Following over 100 years of unsuccessful attempts, [[Friedrich Bessel]], Thomas Henderson and Otto Struve measure the [[parallax]] of a few nearby stars; this is the first measurement of any distances outside the solar system. * '''1848'''&nbsp;— [[Edgar Allan Poe]] offers first correct solution to Olbers' paradox in ''[[Eureka: A Prose Poem]]'', an essay that also suggests the expansion and collapse of the universe * '''1860s'''&nbsp;- [[William Huggins]] develops astronomical [[spectroscopy]]; he shows that the [[Orion nebula]] is mostly made of gas, while the Andromeda nebula (later called [[Andromeda Galaxy]]) is probably dominated by stars. ==1900–1949== * '''1905'''&nbsp;— [[Albert Einstein]] publishes the [[Special Relativity|Special Theory of Relativity]], positing that space and time are not separate continua * '''1912'''&nbsp;- [[Henrietta Leavitt]] discovers the period-luminosity law for [[Cepheid variable]] stars, which becomes a crucial step in measuring distances to other galaxies. * '''1915'''&nbsp;— Albert Einstein publishes the [[General Theory of Relativity]], showing that an energy density warps [[spacetime]] * '''1917'''&nbsp;— [[Willem de Sitter]] derives an isotropic static cosmology with a [[cosmological constant]], as well as an empty [[metric expansion of space|expanding cosmology]] with a cosmological constant, termed a [[de Sitter universe]] * '''1920'''&nbsp;— The [[Shapley-Curtis Debate]], on the distances to spiral nebulae, takes place at the [[Smithsonian]] * '''1921'''&nbsp;— The [[United States National Research Council|National Research Council]] (NRC) published the official transcript of the [[Shapley-Curtis Debate]] * '''1922'''&nbsp;— [[Vesto Slipher]] summarizes his findings on the [[galaxy|spiral nebulae]]'s systematic [[redshift]]s * '''1922'''&nbsp;— [[Alexander Friedmann]] finds a solution to the [[Einstein field equation]]s which suggests a general expansion of space * '''1923'''&nbsp;— [[Edwin Hubble]] measures distances to a few nearby spiral nebulae (galaxies), the [[Andromeda Galaxy]] (M31), [[Triangulum Galaxy]] (M33), and [[NGC 6822]]. The distances place them far outside our Milky Way, and implies that fainter galaxies are much more distant, and the universe is composed of many thousands of galaxies. * '''1927'''&nbsp;— [[Georges Lemaître]] discusses the creation event of an expanding universe governed by the Einstein field equations. From its solutions to the Einstein equations, he predicts the distance-redshift relation. * '''1928'''&nbsp;— [[Howard P. Robertson]] briefly mentions that Vesto Slipher's redshift measurements combined with brightness measurements of the same galaxies indicate a redshift-distance relation * '''1929'''&nbsp;— [[Edwin Hubble]] demonstrates the linear redshift-distance relation and thus shows the expansion of the universe * '''1933'''&nbsp;— [[Edward Arthur Milne|Edward Milne]] names and formalizes the [[cosmological principle]] * '''1933'''&nbsp;— [[Fritz Zwicky]] shows that the [[Coma cluster]] of galaxies contains large amounts of dark matter. This result agrees with modern measurements, but is generally ignored until the 1970s. * '''1934'''&nbsp;— [[Georges Lemaître]] interprets the cosmological constant as due to a [[vacuum energy]] with an unusual perfect fluid [[equation of state]] * '''1938'''&nbsp;— [[Paul Dirac]] suggests the [[Dirac large numbers hypothesis|large numbers hypothesis]], that the gravitational constant may be small because it is decreasing slowly with time * '''1948'''&nbsp;— [[Ralph Alpher]], [[Hans Bethe]] ([[Alpher-Bethe-Gamov paper|"in absentia"]]), and [[George Gamow]] examine element synthesis in a rapidly expanding and cooling universe, and suggest that the elements were produced by rapid [[neutron]] capture * '''1948'''&nbsp;— [[Hermann Bondi]], [[Thomas Gold]], and [[Fred Hoyle]] propose [[steady state theory|steady state]] cosmologies based on the perfect cosmological principle * '''1948'''&nbsp;— [[George Gamow]] predicts the existence of the [[cosmic microwave background radiation]] by considering the behavior of primordial radiation in an expanding universe ==1950–1999== * '''1950'''&nbsp;— [[Fred Hoyle]] coins the term "Big Bang", saying that it was not derisive; it was just a striking image meant to highlight the difference between that and the Steady-State model. * '''1961'''&nbsp;— [[Robert Dicke]] argues that [[carbon]]-based [[life]] can only arise when the gravitational force is small, because this is when burning stars exist; first use of the weak [[anthropic principle]] * '''1963'''&nbsp;— [[Maarten Schmidt]] discovers the first [[quasar]]; these soon provide a probe of the universe back to substantial redshifts. * '''1965'''&nbsp;— [[Hannes Alfvén]] proposes the now-discounted concept of [[ambiplasma]] to explain [[baryon asymmetry]] and supports the idea of an infinite universe. * '''1965'''&nbsp;— [[Martin Rees]] and [[Dennis Sciama]] analyze [[quasar]] source count data and discover that the quasar density increases with redshift. * '''1965'''&nbsp;— [[Arno Penzias]] and [[Robert Woodrow Wilson|Robert Wilson]], astronomers at [[Bell Labs]] discover the 2.7 K ''microwave background radiation'', which earns them the 1978 [[Nobel Prize]] in Physics. [[Robert Dicke]], [[Jim Peebles|James Peebles]], Peter Roll and [[David Todd Wilkinson]] interpret it as a relic from the big bang. * '''1966'''&nbsp;— [[Stephen Hawking]] and [[George Francis Rayner Ellis|George Ellis]] show that any plausible general relativistic cosmology is [[gravitational singularity|singular]] * '''1966'''&nbsp;— [[Jim Peebles|James Peebles]] shows that the hot [[Big Bang]] predicts the correct helium abundance * '''1967'''&nbsp;— [[Andrei Sakharov]] presents the requirements for [[baryogenesis]], a [[baryon]]-[[antimatter|antibaryon]] [[asymmetry]] in the universe * '''1967'''&nbsp;— [[John Bahcall]], [[Wal Sargent]], and [[Maarten Schmidt]] measure the fine-structure splitting of [[spectral line]]s in 3C191 and thereby show that the [[fine-structure constant]] does not vary significantly with time * '''1967'''&nbsp;— [[Robert Wagner]], [[William Alfred Fowler|William Fowler]], and Fred Hoyle show that the hot Big Bang predicts the correct [[deuterium]] and [[lithium]] abundances * '''1968'''&nbsp;— [[Brandon Carter]] speculates that perhaps the fundamental constants of nature must lie within a restricted range to allow the emergence of life; first use of the strong anthropic principle * '''1969'''&nbsp;— [[Charles Misner]] formally presents the Big Bang [[horizon problem]] * '''1969'''&nbsp;— Robert Dicke formally presents the Big Bang flatness problem * '''1970'''&nbsp;— [[Vera Rubin]] and Kent Ford measure spiral galaxy rotation curves at large radii, showing evidence for substantial amounts of [[dark matter]]. * '''1973'''&nbsp;— [[Edward Tryon]] proposes that the universe may be a large scale [[quantum mechanics|quantum mechanical]] [[quantum fluctuation|vacuum fluctuation]] where positive mass-energy is balanced by negative gravitational [[potential energy]] * '''1976'''&nbsp;— [[Alex Shlyakhter]] uses [[samarium]] ratios from the [[Oklo]] prehistoric [[natural nuclear fission reactor]] in [[Gabon]] to show that some laws of physics have remained unchanged for over two billion years * '''1977'''&nbsp;— [[Gary Steigman]], [[David Schramm (astrophysicist)|David Schramm]], and [[James Gunn (astronomer)|James Gunn]] examine the relation between the primordial helium abundance and number of neutrinos and claim that at most five [[lepton]] families can exist. * '''1980'''&nbsp;— [[Alan Guth]] and Alexei Starobinsky independently propose the [[cosmic inflation|inflation]]ary Big Bang universe as a possible solution to the horizon and flatness problems. * '''1981'''&nbsp;— [[Viacheslav Mukhanov]] and G. Chibisov propose that quantum fluctuations could lead to large scale structure in an [[cosmic inflation|inflationary]] universe. * '''1982'''&nbsp;— The first CfA galaxy redshift survey is completed. * '''1982'''&nbsp;— Several groups including [[Jim Peebles|James Peebles]], J. Richard Bond and George Blumenthal propose that the universe is dominated by cold [[dark matter]]. * '''1983 - 1987''' &nbsp;— The first large computer simulations of cosmic structure formation are run by Davis, Efstathiou, Frenk and White. The results show that cold dark matter produces a reasonable match to observations, but hot dark matter does not. * '''1988'''&nbsp;— The [[CfA2 Great Wall]] is discovered in the CfA2 redshift survey. * '''1988'''&nbsp;— Measurements of galaxy large-scale flows provide evidence for the [[Great Attractor]]. * '''1990'''&nbsp;— Preliminary results from [[NASA]]'s [[Cosmic Background Explorer|COBE]] mission confirm the [[cosmic microwave background radiation]] has a [[blackbody]] spectrum to an astonishing one part in 10⁵ precision, thus eliminating the possibility of an integrated starlight model proposed for the background by steady state enthusiasts. * '''1992'''&nbsp;— Further [[Cosmic Background Explorer|COBE]] measurements discover the very small [[anisotropy]] of the [[cosmic microwave background]], providing a "baby picture" of the seeds of large-scale structure when the universe was around 1/1100th of its present size and 380,000 years old. * '''1996'''&nbsp;— The first [[Hubble Deep Field]] is released, providing a clear view of very distant galaxies when the universe was around one-third of its present age. * '''1998'''&nbsp;— Controversial evidence for the [[fine structure constant]] varying over the lifetime of the universe is first published. * '''1998'''&nbsp;— The [[Supernova Cosmology Project]] and [[High-Z Supernova Search Team]] discover [[dark energy|cosmic acceleration]] based on distances to [[Type Ia supernova]]e, providing the first direct evidence for a non-zero [[cosmological constant]]. * '''1999'''&nbsp;— Measurements of the [[cosmic microwave background radiation]] with finer resolution than COBE, (most notably by the [[BOOMERanG experiment]] see Mauskopf et al., 1999, Melchiorri et al., 1999, de Bernardis et al. 2000) provide evidence for oscillations (the first acoustic peak) in the [[anisotropy]] angular spectrum, as expected in the standard model of cosmological structure formation. The angular position of this peak indicates that the geometry of the universe is close to flat. ==Since 2000== * '''2001'''&nbsp;— The [[2dF Galaxy Redshift Survey]] (2dF) by an Australian/British team gave strong evidence that the matter density is near 25% of critical density. Together with the CMB results for a flat universe, this provides independent evidence for a [[cosmological constant]] or similar [[dark energy]]. * '''2002'''&nbsp;— The [[Cosmic Background Imager]] (CBI) in [[Chile]] obtained images of the cosmic microwave background radiation with the highest angular resolution of 4 arc minutes. It also obtained the anisotropy spectrum at high-resolution not covered before up to l ~ 3000. It found a slight excess in power at high-resolution (l > 2500) not yet completely explained, the so-called "CBI-excess". * '''2003'''&nbsp;— NASA's [[Wilkinson Microwave Anisotropy Probe]] (WMAP) obtained full-sky detailed pictures of the cosmic microwave background radiation. The images can be interpreted to indicate that the universe is 13.7 billion years old (within one percent error), and are very consistent with the [[Lambda-CDM model]] and the density fluctuations predicted by [[cosmic inflation|inflation]]. * '''2003'''&nbsp;— The [[Sloan Great Wall]] is discovered. * '''2004'''&nbsp;— The Degree Angular Scale Interferometer (DASI) first obtained the E-mode polarization spectrum of the cosmic microwave background radiation. * '''2005'''&nbsp;— The [[Sloan Digital Sky Survey]] (SDSS) and [[2dF Galaxy Redshift Survey|2dF]] redshift surveys both detected the [[baryon acoustic oscillation]] feature in the galaxy distribution, a key prediction of cold [[dark matter]] models. * '''2006'''&nbsp;— The long-awaited three-year [[WMAP]] results are released, confirming previous analysis, correcting several points, and including [[Cosmic microwave background radiation#Polarization|polarization]] data. * '''2006–2011'''&nbsp;— Improved measurements from [[WMAP]], new supernova surveys ESSENCE and SNLS, and baryon acoustic oscillations from [[Sloan Digital Sky Survey|SDSS]] and [[Astronomical survey#List of sky surveys|WiggleZ]], continue to be consistent with the standard [[Lambda-CDM model]]. * '''2014'''&nbsp;— On March 17, 2014, astrophysicists of the [[BICEP and Keck Array|BICEP2]] collaboration announced the detection of inflationary [[gravitational waves]] in the [[B-modes|B-mode]] [[power spectrum]], which if confirmed, would provide clear experimental evidence for the [[Inflation (cosmology)|theory of inflation]].<ref name="BICEP2-2014">{{cite web |author=Staff |title=BICEP2 2014 Results Release |url=http://bicepkeck.org |date=March 17, 2014 |work=[[National Science Foundation]] |accessdate=March 18, 2014 }}</ref><ref name="NASA-20140317">{{cite web |last=Clavin |first=Whitney |title=NASA Technology Views Birth of the Universe |url=http://www.jpl.nasa.gov/news/news.php?release=2014-082 |date=March 17, 2014 |work=[[NASA]] |accessdate=March 17, 2014 }}</ref><ref name="NYT-20140317">{{cite news |last=Overbye |first=Dennis |authorlink=Dennis Overbye |title=Space Ripples Reveal Big Bang’s Smoking Gun |url=https://www.nytimes.com/2014/03/18/science/space/detection-of-waves-in-space-buttresses-landmark-theory-of-big-bang.html |date=March 17, 2014 |work=[[The New York Times]] |accessdate=March 17, 2014 }}</ref><ref name="NYT-20140324">{{cite news |last=Overbye |first=Dennis |authorlink=Dennis Overbye |title=Ripples From the Big Bang |url=https://www.nytimes.com/2014/03/25/science/space/ripples-from-the-big-bang.html |date=March 24, 2014 |work=[[New York Times]] |accessdate=March 24, 2014 }}</ref><ref name="PRL-20140619"/><ref>{{Cite web | url=http://www.math.columbia.edu/~woit/wordpress/?p=6865 | title=BICEP2 News &#124; Not Even Wrong}}</ref> However, on June 19, 2014, lowered confidence in confirming the [[cosmic inflation]] findings was reported.<ref name="PRL-20140619">{{cite journal |author=Ade, P.A.R. |author2=BICEP2 Collaboration |title=Detection of B-Mode Polarization at Degree Angular Scales by BICEP2 |date=June 19, 2014 |journal=[[Physical Review Letters]] |volume=112 |issue=24 |page=241101 |doi=10.1103/PhysRevLett.112.241101 |arxiv = 1403.3985 |bibcode = 2014PhRvL.112x1101B |pmid=24996078}}</ref><ref name="NYT-20140619">{{cite news |last=Overbye |first=Dennis |authorlink=Dennis Overbye |title=Astronomers Hedge on Big Bang Detection Claim |url=https://www.nytimes.com/2014/06/20/science/space/scientists-debate-gravity-wave-detection-claim.html |date=June 19, 2014 |work=[[New York Times]] |accessdate=June 20, 2014 }}</ref><ref name="BBC-20140619">{{cite news |last=Amos |first=Jonathan |title=Cosmic inflation: Confidence lowered for Big Bang signal |url=https://www.bbc.com/news/science-environment-27935479 |date=June 19, 2014 |work=[[BBC News]] |accessdate=June 20, 2014 }}</ref> * '''2016'''&nbsp;— On February 11, 2016, [[LIGO Scientific Collaboration]] and [[Virgo interferometer|Virgo Collaboration]] announced that gravitational waves were [[First observation of gravitational waves|directly detected]] by two [[LIGO]] detectors. The [[waveform]] matched the prediction of [[General relativity]] for a gravitational wave emanating from the inward spiral and merger of a pair of [[black hole]]s of around 36 and 29 [[solar mass]]es and the subsequent "ringdown" of the single resulting black hole.<ref>{{Cite journal|title = Observation of Gravitational Waves from a Binary Black Hole Merger|journal = [[Physical Review Letters]]|date = 2016-02-11|issn = 0031-9007|volume = 116|issue = 6|doi = 10.1103/PhysRevLett.116.061102|language = en|first = B. P.|last = Abbott|first2 = R.|last2 = Abbott|first3 = T. D.|last3 = Abbott|first4 = M. R.|last4 = Abernathy|first5 = F.|last5 = Acernese|first6 = K.|last6 = Ackley|first7 = C.|last7 = Adams|first8 = T.|last8 = Adams|first9 = P.|last9 = Addesso|arxiv = 1602.03837 |bibcode = 2016PhRvL.116f1102A|pmid=26918975|pages=061102}}</ref><ref name="Nature_11Feb16">{{cite journal |title=Einstein's gravitational waves found at last |journal=Nature News |url=http://www.nature.com/news/einstein-s-gravitational-waves-found-at-last-1.19361 |date=11 February 2016 |last=Castelvecchi |first=Davide |last2=Witze |first2=Alexandra |doi=10.1038/nature.2016.19361 |accessdate=11 February 2016}}</ref><ref name ="renn">{{cite web |last1=Blum |first1=Alexander |last2=Lalli |first2=Roberto |last3=Renn |first3=Jürgen |authorlink3=Jürgen Renn |title=The long road towards evidence |url=http://www.mpg.de/9966773/background |work=[[Max Planck Society]] |date=12 February 2016 |accessdate=15 February 2016}}</ref> The [[GW151226|second detection]] verified that GW150914 is not a fluke, thus opens entire new branch in astrophysics, [[gravitational-wave astronomy]].<ref name="PRL-20160615" >{{Cite journal| collaboration=LIGO Scientific Collaboration and Virgo Collaboration| last=Abbott| first=B. P.| date=15 June 2016| title=GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence| journal=Physical Review Letters| volume= 116| issue= 24| pages=241103|doi=10.1103/PhysRevLett.116.241103| pmid=27367379|arxiv = 1606.04855 |bibcode = 2016PhRvL.116x1103A }}</ref><ref>{{Cite web| url=http://physicsworld.com/cws/article/news/2016/jun/15/ligo-detects-second-black-hole-merger| title=LIGO detects second black-hole merger |date=15 June 2016| first=Tushna| last=Commissariat| website=[[Physics World]]| publisher= [[Institute of Physics]]| access-date=15 June 2016}}</ref> <!--- More informative details could be added here. ---> ==See also== {{Portal|Cosmology|Space}} ===Physical cosmology=== * [[Chronology of the universe]] ** [[Graphical timeline of the Big Bang]] ** [[Graphical timeline from Big Bang to Heat Death]] ** [[Timeline of cosmic microwave background astronomy]] * [[List of cosmologists]] * [[Non-standard cosmology]] ===Belief systems=== * [[Buddhist cosmology]] * [[Jain cosmology]] * [[Jainism and non-creationism]] * [[Hindu cosmology]] * [[Maya mythology]] ===Others=== * [[Cosmology@Home]] ==References== {{Reflist|2}} * {{cite book | last = Horowitz | first = Wayne | title = Mesopotamian cosmic geography | date = 1998 | publisher = [[Eisenbrauns]] | url = https://books.google.com/?id=P8fl8BXpR0MC&printsec=frontcover&dq=Mesopotamian+cosmic+geography#v=onepage&q=Mesopotamian%20cosmic%20geography&f=false | ref = harv | isbn = 9780931464997 }} * Bunch, Bryan, and Alexander Hellemans, "''The History of Science and Technology: A Browser's Guide to the Great Discoveries, Inventions, and the People Who Made Them from the Dawn of Time to Today''". {{ISBN|0-618-22123-9}} * P. Mauskopf et al.,astro-ph/9911444, Astrophys. J. 536 (2000) L59-L62. * A. Melchiorri et al.,astro-ph/9911445, Astrophys. J. 536 (2000) L63-L66. * P. de Bernardis et al., astro-ph/0004404, Nature 404 (2000) 955-959. * A. Readhead et al., Polarization observations with the Cosmic Background Imager, Science 306 (2004), 836-844. {{DEFAULTSORT:Cosmology}} [[Category:Astronomy timelines]] [[Category:Physical cosmology]] [[Category:Lists of inventions or discoveries]] [[Category:Physics timelines]]'