Timeline Of Cosmology

Information about Timeline Of Cosmology

For a timeline of the cosmos (or universe), see .

This timeline of cosmological theories and discoveries is a chronological catalog of the evolution of humankind's understanding of the cosmos over the last two-plus millennia. Modern cosmological conceptions follow the development of the scientific discipline of physical cosmology.

Pre-1900

3rd century BC- Aristarchus of Samos proposes a Sun-centered Universe
2nd century - Ptolemy proposes an Earth-centred Universe, with the Sun and planets revolving around the Earth
c500 onwards - Several astronomers propose a Sun-centered Universe, including Aryabhata, Bhaskara I, Ibn al-Shatir, and Copernicus
1576 - Thomas Digges modifies the Copernican system by removing its outer edge and replacing the edge with a star-filled unbounded space
1584 - Giordano Bruno proposes a non-hierarchical cosmology, wherein the Copernican solar system is not the centre of the universe, but rather, a relatively insignificant star system, amongst an infinite multitude of others
1610 - Johannes Kepler uses the dark night sky to argue for a finite universe
1687 - Sir Isaac Newton's laws describe large-scale motion throughout the universe
1720 - Edmund Halley puts forth an early form of Olbers' paradox
1744 - Jean-Philippe de Cheseaux puts forth an early form of Olbers' paradox
1791 - Erasmus Darwin pens the first description of a cyclical expanding and contracting universe in his poem The Economy of Vegetation
1826 - Heinrich Wilhelm Olbers puts forth Olbers' paradox
1848 - Edgar Allan Poe offers first correct solution to Olbers' paradox in "Eureka," an essay that also suggests the expansion and collapse of the universe

1900-1949

1905 - Albert Einstein publishes the Special Theory of Relativity, positing that space and time are not separate continuums
1915 - Albert Einstein publishes the General Theory of Relativity, showing that an energy density warps spacetime
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
1922 - Vesto Slipher summarizes his findings on the spiral nebulae's systematic redshifts
1922 - Alexander Friedmann finds a solution to the Einstein field equations which suggests a general expansion of space
1927 - Georges Lemaître discusses the creation event of an expanding universe governed by the Einstein field equations
1928 - Howard Percy Robertson briefly mentions that Vesto Slipher's redshift measurements combined with brightness measurements of the same galaxies indicate a redshift-distance relation
1929 - Edwin Hubble demonstrates the linear redshift-distance relation and thus shows the expansion of the universe
1933 - Edward Milne names and formalizes the cosmological principle
1934 - Georges Lemaître interprets the cosmological constant as due to a vacuum energy with an unusual perfect fluid equation of state
1938 - Paul Dirac suggests the large numbers hypothesis, that the gravitational constant may be small because it is decreasing slowly with time
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
1948 - Hermann Bondi, Thomas Gold, and Fred Hoyle propose steady state cosmologies based on the perfect cosmological principle
1948 - George Gamow predicts the existence of the cosmic microwave background radiation by considering the behavior of primordial radiation in an expanding universe.

1950 to 1999

1950 - Fred Hoyle derisively coins the term "Big Bang".
1961 - 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
1965 - Hannes Alfvén proposes the now-discounted concept of ambiplasma to explain baryon asymmetry.
1965 - Martin Rees and Dennis Sciama analyze quasar source count data and discover that the quasar density increases with redshift.
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.
1966 - Stephen Hawking and George Ellis show that any plausible general relativistic cosmology is singular
1966 - James Peebles shows that the hot Big Bang predicts the correct helium abundance
1967 - Andrei Sakharov presents the requirements for baryogenesis, a baryon-antibaryon asymmetry in the universe
1967 - John Bahcall, Wal Sargent, and Maarten Schmidt measure the fine-structure splitting of spectral lines in 3C191 and thereby show that the fine-structure constant does not vary significantly with time
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
1969 - Charles Misner formally presents the Big Bang horizon problem
1969 - Robert Dicke formally presents the Big Bang flatness problem
1973 - Edward Tryon proposes that the universe may be a large scale quantum mechanical vacuum fluctuation where positive mass-energy is balanced by negative gravitational potential energy
1974 - Robert Wagoner, William Fowler, and Fred Hoyle show that the hot Big Bang predicts the correct deuterium and lithium abundances
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
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.
1981 - Viacheslav Mukhanov and G. Chibisov propose that quantum fluctuations could lead to large scale structure in an inflationary universe
1981 - Alan Guth proposes the inflationary Big Bang universe as a possible solution to the horizon and flatness problems
1990 - Preliminary results from NASA's COBE mission confirm the cosmic microwave background radiation is an isotropic blackbody 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.
1990s - Ground based cosmic microwave background experiments measure the first peak, determine that the universe is geometrically flat.
1998 - Controversial evidence for the fine structure constant varying over the lifetime of the universe is first published.
1998 - Adam Riess, Saul Perlmutter and others discover the cosmic acceleration in observations of Type Ia supernovae providing the first evidence for a non-zero cosmological constant.
1999 - Measurements of the cosmic microwave background radiation (most notably by the BOOMERanG experiment see Mauskopf et al., 1999, Melchiorri et al., 1999, de Bernardis et al. 2000) provide evidence for oscillations (peaks) in the anisotropy angular spectrum as expected in the standard model of cosmological structure formation. These results indicates that the geometry of the universe is flat. Together with large scale structure data, this provides complementary evidence for a non-zero cosmological constant.

Since 2000

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 Lambda-CDM model and the inflationary theory are correct.
2003 - The Sloan Great Wall is discovered.
2006 - The long-awaited three-year WMAP results are released, confirming previous analysis, correcting several points, and including polarization data.

References

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.

Physical cosmology, as a branch of astronomy, is the study of the large-scale structure of the universe and is concerned with fundamental questions about its formation and evolution. Cosmology involves itself with studying the motions of the celestial bodies and the first cause.
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The age of the universe, in physics, is the time elapsed between the Big Bang and the present day. Current observations suggest that this is about 13.7 billion years, with an uncertainty of about +/-200 million years.
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Big Bang is the cosmological model of the universe whose primary assertion is that the universe has expanded into its current state from a primordial condition of enormous density and temperature.
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Blue Shift refers to a shortening of a transmitted signal's wavelength, and/or an increase in its frequency. The name comes from the fact that the shorter-wavelength end of the optical spectrum is the blue (or violet) end, hence, when visible light is compacted in
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In standard cosmology, 'comoving' distance or 'proper distance' is one of several distance measures used by cosmologists to define distances between objects.

Comoving coordinates

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cosmic microwave background radiation (most often abbreviated CMB but occasionally CMBR, CBR or MBR, also referred to as relic radiation) is a form of electromagnetic radiation discovered in 1965 that fills the entire universe ^[1].
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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. ^[1]
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In astrophysics and cosmology, dark matter is 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.
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Friedmann-Lemaître-Robertson-Walker (FLRW) metric is an exact solution of the Einstein field equations of general relativity; it describes a , isotropic expanding or contracting universe.
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The Friedmann equations are a set of equations in cosmology that govern the expansion of space in homogeneous and isotropic models of the universe within the context of general relativity.
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formation of galaxies is still one of the most active research areas in astrophysics; and, to some extent, this is also true for galaxy evolution. Some ideas, however, have gained wide acceptance.
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Hubble's law is a statement in physical cosmology which states that the redshift in light coming from distant galaxies is proportional to their distance. The law was first formulated by Edwin Hubble and Milton Humason in 1929^[1] after nearly a decade of observations.
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In physical cosmology, cosmic inflation is the idea that the nascent universe passed through a phase of exponential expansion that was driven by a negative-pressure vacuum energy density.
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large-scale structure refers to the characterization of observable distributions of matter and light on the largest scales (typically on the order of billions of light-years).
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ΛCDM or Lambda-CDM is an abbreviation for Lambda-Cold Dark Matter. It is frequently referred to as the concordance model of big bang cosmology, since it attempts to explain cosmic microwave background observations, as well as large scale structure
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The metric expansion of space is a key part of science's current understanding of the universe, whereby spacetime itself is described by a metric which changes over time in such a way that the spatial dimensions appear to grow or stretch as the universe gets older.
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In physical cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than those of H-1 (i.e. the normal, light isotope of hydrogen, whose nuclei consist of a single proton each) during the early phases of the
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This article or section may contain inappropriate or misinterpreted which do not the text.
Please help [ improve this article] by checking for inaccuracies. This article has been tagged since October 2007.
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redshift occurs when the electromagnetic radiation, usually visible light, that is emitted from or reflected off an object is shifted toward the (less energetic) red end of the electromagnetic spectrum.
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The shape of the Universe is an informal name for a subject of investigation within physical cosmology. Cosmologists and astronomers describe the geometry of the universe which includes both local geometry and global geometry.
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Structure formation refers to a fundamental problem in physical cosmology. The universe, as is now known from observations of the cosmic microwave background radiation, began in a hot, dense, nearly uniform state approximately 13.7 Gyr ago.
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Physical cosmology

Age of the universe
Big Bang
Blueshift
Comoving distance
Cosmic microwave background
Dark energy
Dark matter
FLRW metric
Friedmann equations
Galaxy formation
Hubble's law
Inflation

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The ultimate fate of the universe is a topic in physical cosmology. Many possible fates are predicted by rival scientific theories, including futures of both finite and infinite duration.
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The Universe is defined as the summation of all particles and energy that exist and the space-time in which all events occur. Based on observations of the portion of the Universe that is observable, physicists attempt to describe the whole of space-time, including all matter and
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Astronomy is the scientific study of celestial objects (such as stars, planets, comets, and galaxies) and phenomena that originate outside the Earth's atmosphere (such as the cosmic background radiation).
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General relativity (GR) (aka general theory of relativity (GTR)) is the geometrical theory of gravitation published by Albert Einstein in 1915/16.^[1] It unifies special relativity, Newton's law of universal gravitation, and the insight that gravitational
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Particle physics is a branch of physics that studies the elementary constituents of matter and radiation, and the interactions between them. It is also called "high energy physics"
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Quantum gravity is the field of theoretical physics attempting to unify quantum mechanics, which describes three of the fundamental forces of nature, with general relativity, the theory of the fourth fundamental force: gravity.
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Chronology is the science of locating events in time. An arrangement of events, from either earliest to latest or the reverse, is also called a chronology or, particularly when involving graphical elements, a timeline or a living graph. See also Chronicle.
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cosmos is an orderly or harmonious system. It originates from a Greek term κόσμος meaning "order, orderly arrangement, ornaments," and is the antithetical concept of chaos.
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