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-Lemaître-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 – 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 (Александр Александрович Фридман) (June 16, 1888 – September 16, 1925) was a Russian cosmologist and mathematician. ... Father Georges-Henri Lemaître (July 17, 1894 – June 20, 1966) was a Belgian Roman Catholic priest, honorary prelate, professor of physics and astronomer. ... Edwin Powell Hubble (November 29, 1889 – 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 – August 19, 1968) , born Georgiy Antonovich Gamov (Георгий Антонович Гамов) was a Ukrainian born physicist and cosmologist. ... Robert Henry Dicke (May 6, 1916 – 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:Яков Борисович Зельдович) (March 8, 1914 – 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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In cosmology, the steady state theory (also known as the Infinite Universe Theory or continuous creation) is a model developed in 1948 by Fred Hoyle, Thomas Gold, Hermann Bondi and others as an alternative to the Big Bang theory (known, usually, as the standard cosmological model). In some steady state views, new matter is continuously created as the universe expands, so that the perfect cosmological principle is adhered to. Although the model had a large number of supporters among cosmologists in the 1950s and 1960s, the number of supporters decreased markedly in the late 1960s with the discovery of the cosmic microwave background radiation, and today only a very small number of supporters remain. The key importance of the steady-state model is that as a competitor to the Big Bang, it was an impetus in generating some of the most important research in astrophysics, much of which ultimately ended up supporting the Big Bang theory. 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. ... 1948 (MCMXLVIII) was a leap year starting on Thursday (the link is to a full 1948 calendar). ... Sir Frederick Hoyle (born on June 24, 1915 in Gilstead, Yorkshire, England – August 20, 2001 in Bournemouth, England)[1] was a British astronomer, notable for a number of his theories that run counter to current astronomical opinion, and a writer of science fiction, including a number of books co-authored... Thomas Gold (May 22, 1920 – June 22, 2004) was an Austrian astrophysicist, a professor of astronomy at Cornell University, and a member of the US National Academy of Sciences. ... Professor Sir Hermann Bondi, KCB , FRS (1 November 1919–10 September 2005) was a British (formerly Austrian) mathematician and cosmologist. ... A non-standard cosmology is any cosmological framework that has been, or still is, proposed as an alternative to the big bang model of physical cosmology. ... According to the Big Bang model, the universe emerged from an extremely dense and hot state. ... The Perfect Cosmological Principle is an extension of the Cosmological Principle stating that the Universe is not only homogeneous and isotropic in space, but also in time. ... This does not cite its references or sources. ... The 1960s decade refers to the years from January 1, 1960 to December 31, 1969, inclusive. ... 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. ...

Overview

Problems

Problems with the steady-state theory began to emerge in the late 1960s, when observations apparently supported the idea that the universe was in fact changing: quasars and radio galaxies were found only at large distances (i.e., redshift, and thus, because of the finiteness of the speed of light, in the past) not in closer galaxies. Halton Arp, also since the 1960s, has been taking a different view of the data, claiming that evidence can also point to quasars existing as close as the local Virgo cluster, however, this theory is not accepted by mainstream scientists today. Artists impression of quasar GB1508 A quasar (contraction of QUASi-stellAR radio source) is an astronomical source of electromagnetic energy, including radio waves and visible light. ... An active galaxy is a galaxy where a significant fraction of the energy output is not emitted by the normal components of a galaxy: stars, dust and interstellar gas. ... A line showing the speed of light on a scale model of Earth and the Moon The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness. It is the speed of all electromagnetic radiation... Halton Arp in London, Oct 2000 Halton Christian Arp is an American astronomer. ... A sky field near some of the brighter galaxies in the Virgo cluster. ...

For most cosmologists, the refutation of the steady-state theory came with the discovery of the cosmic background radiation in 1965, which was predicted by the big bang theory. Stephen Hawking said that the fact that microwave radiation had been found, and that it was thought to be left over from the big bang, was "the final nail in the coffin of the steady-state theory." Within the steady state theory this background radiation is the result of light from ancient stars which has been scattered by galactic dust. However, this explanation has been unconvincing to most cosmologists as the cosmic microwave background is very smooth, making it difficult to explain how it arose from point sources, and the microwave background shows no evidence of features such as polarization which are normally associated with scattering. Furthermore, its spectrum is so close to that of an ideal black body that it could hardly be formed by the superposition of contributions from dust clumps at different temperatures as well as at different redshifts. Steven Weinberg wrote in 1972, When any patch of the sky is observed where no individual sources can be discerned, and the effects of interplanetary dust, and interstellar matter are taken into account, there is still radiation. ... 1965 (MCMLXV) was a common year starting on Friday (the link is to a full 1965 calendar). ... Stephen William Hawking, CH, CBE, FRS, FRSA, (born 8 January 1942) is a British theoretical physicist. ... As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ... Redshift of spectral lines in the optical spectrum of a supercluster of distant galaxies (right), as compared with that of the Sun (left). ... Steven Weinberg (born May 3, 1933) is an American physicist. ...

The steady state model does not appear to agree with the observed d_L versus z relation or with source counts ... In a sense, the disagreement is a credit to the model; alone among all cosmologies, the steady state model makes such definite predictions that it can be disproved even with the limited observational evidence at our disposal. The steady-state model is so attractive that many of its adherents still retain hope that the evidence against it will disappear as observations improve. However, if the cosmic microwave background radiation ... is really black-body radiation, it will be difficult to doubt that the universe has evolved from a hotter, denser early stage.

As of 2006, the majority of astronomers consider the big bang theory to be the best description of the origin of the universe. In most astrophysical publications, the big bang is implicitly accepted and is used as the basis of more complete theories. Luminosity distance DL is defined in terms of the relationship between the absolute magnitude M and apparent magnitude m of an astronomical object: which gives: Calculating the luminosity distance of an object correctly from its real distance is quite complex, but there are a number of useful webpages for performing... Redshift of spectral lines in the optical spectrum of a supercluster of distant galaxies (right), as compared with that of the Sun (left). ...

C-field

Bondi and Gold proposed no mechanism for the creation of matter required by the steady state theory, but Hoyle proposed the existence of what he called the "C-field", where "C" stands for "Creation". The C-field has negative pressure, creates the matter, and drives the steady expansion of the cosmos. These properties are all shared by the inflaton field used in cosmic inflation. …In this fashion Hoyle's conception of the steady state in 1948 incorporates many features that later emerged in inflationary cosmology, especially in chaotic inflation theory or eternal inflation which sometimes posits an infinite universe with neither beginning nor end in which inflation operates continuously, on a scale beyond the observable universe, to create the matter of the cosmos. The inflaton is the generic name of the unidentified scalar field (and its associated particle), that may be responsible for an episode of inflation in the very early universe. ... 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. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Chaotic inflation theory, first formulated by Andrei Linde, models quantum fluctuations in the rate of cosmic inflation[1]. Those regions with a higher rate of inflation expand faster and dominate the universe, despite the natural tendency of inflation to end in other regions. ... See universe for a general discussion of the universe. ...

Quasi-steady state

Quasi-steady state cosmology (QSS) was proposed in 1993 by Fred Hoyle, Geoffrey Burbidge, and Jayant V. Narlikar as a new incarnation of steady state ideas meant to explain additional features unaccounted for in the initial proposal. The theory suggests pockets of creation occurring over time within the universe, sometimes referred to as minibangs, mini-creation events, or little bangs, somewhat reminiscent of the ambiplasma domains proposed in Hannes Alfven's cosmology. After the observation of an accelerating universe, further modifications of the model were done.^{[citation needed]} Mainstream cosmologists who have reviewed QSS have pointed out flaws and discrepancies with observations left unexplained by proponents. [1] 1993 (MCMXCIII) was a common year starting on Friday of the Gregorian calendar and marked the Beginning of the International Decade to Combat Racism and Racial Discrimination (1993-2003). ... Sir Frederick Hoyle (born on June 24, 1915 in Gilstead, Yorkshire, England – August 20, 2001 in Bournemouth, England)[1] was a British astronomer, notable for a number of his theories that run counter to current astronomical opinion, and a writer of science fiction, including a number of books co-authored... Geoffrey Ronald Burbidge (born September 24, 1925) is a British-American physics professor in the University of California, San Diego. ... Professor Jayant Vishnu Narlikar (born July 19,1938) (Marathi: प्रा. जयंत विष्णू नारळीकर) is an eminent Indian astrophysicist. ... In the history of cosmology an ambiplasma is a hypothetical plasma containing a mixture of both matter and antimatter. ... Hannes Olof Gösta Alfvén (May 30, 1908; Norrköping, Sweden - April 2, 1995; Djursholm, Sweden) was a Swedish electrical power engineer. ... 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. ...

External articles and references

Criticism

• Errors in the Steady State and Quasi-SS Models by Edward L. Wright, 13 September 2004

Citations

• Hoyle, F., Burbidge, G., and Narlikar, J. V. "A quasi-steady state cosmological model with creation of matter". The Astrophysical Journal, 410: 437-457, 1993.
• F. Hoyle, G. Burbidge, J.V. Narlikar, "Astrophysical deductions from the quasi-steady state cosmology". Mon. Not. R. Astron. Soc., 267, 1007-1019, 1994 (citation search.)
  • F. Hoyle, G. Burbidge, J.V. Narlikar, "Astrophysical deductions from the quasi-steady state : Erratum". Mon. Not. R. Astron. Soc., 269, 1152, 08/1994.
• Hoyle, F., G. Burbidge, and J. V. Narlikar, "Further astrophysical quantities expected in a quasi-steady state Universe". Astronomy and Astrophysics (ISSN 0004-6361), vol. 289, no. 3, p. 729-739.
• Hoyle F, Burbidge G and Narlikar J, "The basic theory underlying the quasi-steady state cosmological model". Proc. R. Soc. A 448 191
• Edward L. Wright "Comments on the Quasi-Steady-State Cosmology". astro-ph/9410070, Astrophysics, abstract. 20 Oct 1994. (ed. Author is a proponent of the Big Bang)
  • F. Hoyle, G. Burbidge, J.V. Narlikar, "Note on a Comment by Edward L. Wright". astro-ph/9412045, Astrophysics, abstract. 14 Dec 1994.

Edward L. (Ned) Wright is an American astrophysicist and cosmologist, well known for his achievements in the Nobel prized (2006) COBE-project and as a strong Big Bang proponent in web tutorials on cosmology and theory of relativity. ... Edward L. (Ned) Wright is an American astrophysicist and cosmologist, well known for his achievements in the Nobel prized (2006) COBE-project and as a strong Big Bang proponent in web tutorials on cosmology and theory of relativity. ...

Books

• Billy Ligon Farmer, Universe Alternatives: Emerging Concepts of Size, Age, Structure, and Behavior, 2nd edition, Gilliland Printing, 1995, ISBN 0-9649983-4-3.
• Fred Hoyle, Geoffrey Burbidge, and Jayant V. Narlikar, A Different Approach to Cosmology, Cambridge University Press, 2000, ISBN 0-521-66223-0.
• Simon Mitton, Conflict in the Cosmos: Fred Hoyle's Life in Science, Joseph Henry Press, 2005, ISBN 0-309-09313-9 or, Fred Hoyle: a life in science, Aurum Press, 2005, ISBN 1-85410-961-8
• Steven Weinberg, Gravitation and Cosmology (Wiley, New York, 1972), pp. 495–464.