 Timeline of universe cosmology lists the sequence of cosmological theories and discoveries in chronological order. The most modern developments follow the scientific development of the discipline of Physical cosmology. Timeline of universe cosmology: Pre1900. timeline of cosmology.  Timeline of universe cosmology: Timeline of universe cosmology: 3rd century BC Aristarchus of Samos proposes a Suncentered Universe.
 Timeline of universe cosmology: Timeline of universe cosmology: 2nd century  Ptolemy proposes an Earthcentred Universe, with the Sun and planets revolving around the Earth.
 Timeline of universe cosmology: c500 onwards  Several astronomers propose a Suncentered universe, including Aryabhata, Bhaskara I, Ibn alShatir, and Copernicus.
 Timeline of universe cosmology: 1576  Thomas Digges modifies the Copernican system by removing its outer edge and replacing the edge with a starfilled unbounded space.
 Timeline of universe cosmology: 1610  Johannes Kepler uses the dark night sky to argue for a finite universe.
 Timeline of universe cosmology: 1687  Sir Isaac Newton's laws describe largescale motion throughout the universe.
 Timeline of universe cosmology: 1720  Edmund Halley puts forth an early form of Olbers' paradox.
 Timeline of universe cosmology: 1744  JeanPhilippe de Cheseaux puts forth an early form of Olbers' paradox.
 Timeline of universe cosmology: 1791  Erasmus Darwin pens the first description of a cyclical expanding and contracting universe.
 Timeline of universe cosmology: 1826  Heinrich Wilhelm Olbers puts forth Olbers' paradox.
 Timeline of universe cosmology: 1848  Edgar Allan Poe offers first correct solution to Olbers' paradox in an essay that also suggests the expansion and collapse of the universe.
Timeline of universe cosmology: 19001949.  Timeline of universe cosmology: 1905  Albert Einstein publishes the special theory of relativity, positing that space and time are not separate continuums.
 Timeline of universe cosmology: 1915  Albert Einstein publishes the General Theory of Relativity, showing that an energy density warps Spacetime.
 Timeline of universe cosmology: 1917  Willem de Sitter derives an isotropic static cosmology with a cosmological constant as well as an empty expanding cosmology with a cosmological constant, termed a de Sitter universe.
 Timeline of universe cosmology: 1922  Vesto Slipher summarizes his findings on the spiral nebulae's systematic redshifts.
 Timeline of universe cosmology: 1922  Alexander Friedmann finds a solution to the Einstein field equations which suggests a general expansion of space.
 Timeline of universe cosmology: 1927  Georges Lemaître discusses the creation event of an expanding universe governed by the Einstein field equations.
 Timeline of universe cosmology: 1928  Howard Percy Robertson briefly mentions that Vesto Slipher's redshift measurements combined with brightness measurements of the same galaxies indicate a redshiftdistance relation.
 Timeline of universe cosmology: 1929  Edwin Hubble demonstrates the linear redshiftdistance relation and thus shows the expansion of the universe.
 Timeline of universe cosmology: 1933  Edward Milne names and formalizes the cosmological principle.
 Timeline of universe cosmology: 1934  Georges Lemaître interprets the cosmological constant as due to a Vacuum energy with an unusual perfect fluid Equation of state.
 Timeline of universe cosmology: 1938  Paul Dirac suggests the large numbers hypothesis, that the gravitational constant may be small because it is decreasing slowly with time.
 Timeline of universe cosmology: 1948  Ralph Alpher, Hans Bethe("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.
 Timeline of universe cosmology: 1948  Hermann Bondi, Thomas Gold, and Fred Hoyle propose steady state cosmologies based on the perfect cosmological principle.
 Timeline of universe cosmology: 1948  George Gamow predicts the existence of the cosmic microwave background radiation by considering the behavior of primordial radiation in an expanding universe.
Timeline of cosmology: 1950 to 1999.  Timeline of universe cosmology: 1950  Oskar Klein proposes a metagalaxy model, a first indication of the AlfvénKlein model.
 Timeline of universe cosmology: 1950  Fred Hoyle derisively coins the term "Big Bang".
 Timeline of universe cosmology: 1951  William McCrea shows that the steady state Cfield can be accommodated within general relativity by interpreting it as a contribution to the energymomentum tensor with an unusual equation of state.
 Timeline of universe cosmology: 1961  Robert Dicke argues that carbonbased life can only arise when the gravitational force is small, because this is when burning stars exist; first use of the weak anthropic principle.
 Timeline of universe cosmology: 1963  Fred Hoyle and Jayant Narlikar show that the steady state theory can explain the isotropy of the universe because deviations from isotropy and homogeneity decay exponentially in time.
 Timeline of universe cosmology: 1964  Fred Hoyle and Roger Tayler point out that the primordial helium abundance depends on the number of neutrinos.
 Timeline of universe cosmology: 1965  Hannes Alfvén proposes the nowdiscounted concept of ambiplasma to explain baryon asymmetry.
 Timeline of universe cosmology: 1965  Martin Rees and Dennis Sciama analyze quasar source count data and discover that the quasar density increases with redshift.
 Timeline of universe cosmology: 1965  Arno Penzias and 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, James Peebles, Peter Roll and David Todd Wilkinson interpret it as relic from the big bang.
 Timeline of universe cosmology: 1966  Stephen Hawking and George Ellis show that any plausible general relativistic cosmology is singular.
 Timeline of universe cosmology: 1966  James Peebles shows that the hot Big Bang predicts the correct helium abundance.
 Timeline of universe cosmology: 1967  Andrei Sakharov presents the requirements for baryogenesis, a baryonantibaryon asymmetry in the universe.
 Timeline of universe cosmology: 1967  John Bahcall, Wal Sargent, and Maarten Schmidt measure the finestructure splitting of spectral lines in 3C191 and thereby show that the finestructure constant does not vary significantly with time.
 Timeline of universe cosmology: 1968  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.
 Timeline of universe cosmology: 1969  Charles Misner formally presents the Big Bang horizon problem.
 1969  Robert Dicke formally presents the Big Bang flatness problem.
 Timeline of universe cosmology: 1973  Edward Tryon proposes that the universe may be a large scale quantum mechanical vacuum fluctuation where positive massenergy is balanced by negative gravitational potential energy.
 Timeline of universe cosmology: 1974  Robert Wagoner, William Fowler, and Fred Hoyle show that the hot Big Bang predicts the correct deuterium and lithium abundances.
 Timeline of universe cosmology: 1976  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.
 Timeline of universe cosmology: 1977  Gary Steigman, David Schramm, and James Gunn examine the relation between the primordial helium abundance and number of neutrinos and claim that at most five lepton families can exist.
 Timeline of universe cosmology: 1981  Viacheslav Mukhanov and G. Chibisov propose that quantum fluctuations could lead to large scale structure in an inflationary universe.
 Timeline of universe cosmology: 1981  Alan Guth proposes the inflationary Big Bang universe as a possible solution to the horizon and flatness problems.
 Timeline of universe cosmology: 1990  Preliminary results from NASA's COBE mission confirm the cosmic microwave background radiation is an isotropic blackbody to an astonishing one part in 10^{5} precision, thus eliminating the possibility of an integrated starlight model proposed for the background by steady state enthusiasts.
 Timeline of universe cosmology: 1990s  Ground based cosmic microwave background experiments measure the first peak, determine that the universe is geometrically flat.
 Timeline of universe cosmology: 1998  Controversial evidence for the fine structure constant varying over the lifetime of the universe is first published.
 Timeline of universe cosmology: 1998  Adam Riess, Saul Perlmutter and others discover the cosmic acceleration in observations of Type Ia supernovae providing the first evidence for a nonzero cosmological constant. This is confirmed by measurements of the cosmic microwave background radiation by the BOOMERanG experiment.
Timeline of cosmology: Since 2000.  Timeline of universe cosmology: 2003  NASA's WMAP takes more detailed pictures of the cosmic microwave background radiation than were obtained by the BOOMERanG experiment. The image can be interpreted to indicate that the universe is 13.7 billion years old (within one percent error) and confirm that the LambdaCDM model and the inflationary theory are correct.
 Timeline of universe cosmology: 2006  The longawaited threeyear WMAP results are released, confirming previous analysis, correcting several points, and including polarization data.
Reference to the Timeline of cosmology.  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 0618221239.
Go To Print Article
