
[[Image:WMAP.jpg|thumb|rightt|300px|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. It has the characteristics of black body radiation at a temperature of 1 E0 K. It has a frequency in the microwave range. ==CMB and the Big Bang== This radiation is regarded as the best available evidence of the Big Bang (BB) theory and its discovery in the mid-1960s curtailed interest for non-standard cosmology such as the steady state theory. The CMB gives a snapshot of the Universe when, according to standard cosmology, the temperature dropped enough to allow electrons and protons to form hydrogen atoms, thus making the universe transparent to radiation. When it originated some 1 E12 s after the Big Bang -- this time period is generally known as the "time of last scattering" or the period of recombination or decoupling -- the temperature of the Universe was about 1 E3 K. Since then the temperature of the radiation has dropped by a factor of roughly 1 E3 due to the expansion of the Universe. As the universe expands, the CMB photons are redshifted, cooling the radiation inversely proportional to the Universe's Scale factor (Universe). For details on reasoning that the radiation is used as evidence of the Big Bang, see Big Bang#Cosmic_microwave_background_radiation. After the creation of the CMB, there are a number of important events. The CMB created hydrogen atoms, but from observations of galaxies, it seems that most of the intergalactic medium consists of ionized material (since there are few absorption lines due to hydrogen atoms). This implies a period of reionization in which the material of the universe breaks down into hydrogen ions. The favored explanation for this is that starlight causes reionization although there is evidence that reionization began before there were large numbers of stars. The period after the emission of the CMB and the observation of the first stars is semi-humorously referred to by cosmologists as the dark age, and is a period which is under intense study by astronomers. [[Image:WMAP power spectrum.jpg|thumb|right|350px|The power spectrum of the cosmic microwave background radiation anisotropy in terms of the multipole moment (top). Data from WMAP have extended the accuracy of the spectrum far beyond what was known from earlier measurements.]] ==Features== One feature of the CMB is how closely it matches a black body. Although the temperature of the CMB varies from point to point (i.e. it contains small anisotropies), the spectrum in a particular direction very closely resembles a black body. Another of the microwave background's salient features is a high degree of isotropic. There are however some Anisotropic as well, the most pronounced of which is the dipole anisotropy (180 degree scales) which is at a level of about 10 −3 of the monopole. This feature is consistent with the Earth moving at some 700 km/s relative to the CMB. Variations due to external physics also exist; the Sunyaev Zeldovic Effect is one of the major factors here, in which a cloud of high energy electrons scatters the radiation, transferring some energy to the CMB photons. Even more interesting are anisotropy at a level of roughly 10 −5 on scales of roughly tens of arcminutes to several degrees. These very small variations are the result of the Sachs-Wolfe effect which causes photons from the cosmic microwave background to be gravitationally redshifted. According to cosmic inflation, the origin of the variations is quantum fluctuations which expand during inflation and result in primordial fluctuations. The angular power spectrum of these variations (in terms of amplitudes of component multipole moments) can be calculated and produces a number of peaks and valleys. The location of these peaks and valleys can be correlated with cosmological parameters such as the Hubble constant, and the shape of the universe. ==Detection, prediction and discovery== ''Main article:'' Discovery of cosmic microwave background radiation The CMB was predicted by George Gamow, Ralph Alpher, and Robert Hermann in the 1940s and was accidentally discovered in 1964 by Arno Penzias and Robert Woodrow Wilson, who received a Nobel Prize in Physics in 1978 for this discovery. The interpretation of the CMB was a very controversial issue in the 1960s with some proponents of the steady state theory arguing that the CMB was the result of scattered starlight from distant galaxies. Using this model, and based on the study of narrow absorption line features in the spectra of stars, the astronomer Andrew McKellar wrote in 1941: "It can be calculated that the 'rotational' temperature of interstellar space is 2 K." However, during the 1970s the consensus view moved to the point of view that the CBR was the remnant of the big bang. Among the observations that swung the astronomical community toward this point of view were the fact that the CBR was much smoother than would be expected from scattered star light. Because water absorbs microwave radiation, a fact that is used to build microwave ovens, it is rather difficult to observe the CMB with ground-based instruments. CMB research therefore makes increasing use of air and space-borne experiments. Ground-based observations of the CMB are usually made from high altitude locations such as the Andes and the South Pole. ==Experiments== Of these experiments, the Cosmic Background Explorer (COBE) satellite that was flown in 1989-1996 is probably the most famous and which made the first detection of the large scale anisotropies (other than the dipole). Inspired by the COBE results, a series of ground and balloon-based experiments measured CMB anisotropies on smaller angular scales over the next decade. The primary goal of these experiments was to measure the scale of the first acoustic peak, which COBE did not have sufficient resolution to resolve. These measurements were able to rule out cosmic strings as a theory of cosmic structure formation, and suggested cosmic inflation was the right theory. The first peak was measured with increasing sensitivity and by 2000 the Boomerang experiment reported that the highest power fluctions occur at one degree scales. Together with other cosmological data, these results implied that the geometry of the Universe is flat space. A number of ground-based interferometer provided measurements of the fluctuations with higher accuracy over the next three years, including the Very Small Array and the Cosmic Background Imager. In June 2001, NASA launched a second CBR space mission, WMAP, to make much more accurate measurements of the large scale anisotropies over the full sky. Results from this mission disclosed in 2003 provided a detailed measurement of the angular power spectrum down to degree scales, tightly constraining various cosmological parameters. The results are broadly consistent with those expected from cosmic inflation as well as various other competing theories, and are available in detail at NASA's data center for Cosmic Microwave Background (CMB) [''ed.'' see links below]. Although WMAP provided very accurate measurements of the large angular-scale fluctuations in the CMB (structures about as large in the sky as the moon), it did not have the angular resolution to measure the small scale fluctuations which had been observed using previous ground-based interferometer. A third space mission, the Planck Surveyor, is to be launched in 2007. Planck employs bolometer technology and will measure the CMB on smaller scales than WMAP. Unlike the previous two space missions, Planck is a collaboration between NASA and European Space Agency (the European Space Agency). Its detectors got a trial run at the Antarctic Viper telescope as ACBAR (Arcminute Cosmology Bolometer Array Receiver) experiment, which gave the currently most precise measurements at high ''l'', and at the Archeops balloon telescope. Additional ground-based instruments such as CLOVER array in Antarctica will provide additional data not available from satellite observations, such as the B-mode polarization component. === List of experiments in approximate chronological order === Each experiment provided improved data quality when compared with previous experiments. * COBE - measured the very large scale fluctuations * Cosmic Anisotropy Telescope - measured the very small scale fluctuations in small regions of the sky * Maxima - measured intermediate scale fluctuations with improved precision * Boomerang experiment - measured intermediate scale fluctuations with improved precision * Cosmic Background Imager - measured the very small scale fluctuations with improved precision in small regions of the sky * Very Small Array - measured intermediate and small scale fluctuations with improved precision in small regions of the sky * WMAP - measured intermediate and large scale fluctuations with improved precision * Arcminute Cosmology Bolometer Array Receiver - measured intermediate and small scale fluctuations with improved precision * CLOVER array - (2008?) - improved precision for small scale fluctuations and B-mode polarization measurements * Planck (satellite) - (2009?) - will give improved precision at all scales ==See also== {|cellpadding="5" |valign="top"| ;Main *Background radiation *COBE *Cosmic inflation *Cosmic background radiation *Gravitational radiations *Microwave *Unsolved problems in physics *WMAP ;Physics and Astronomy *Anisotropy (or Anisotropic) *Baryonic dark matter *Big bang nucleosynthesis, *Black body *Black dwarf *Cold dark matter *Dark energy *Greisen-Zatsepin-Kuzmin limit *History of astronomy *Hubble's law *Integrated Sachs Wolfe effect *Nobel Prize in Physics *Observation *Olbers' paradox *Radio astronomy *Redshift |valign="top"| *Big Bang *Big Crunch ;People *Arno Allan Penzias *Fred Hoyle *Georges Lemaître *Robert Wilson *Robert Woodrow Wilson ;Timelines and lists *List of astronomical topics *List of famous experiments *Timeline of cosmic microwave background astronomy *Timeline of knowledge about galaxies, clusters of galaxies, and large-scale structure *Timeline of the Big Bang *Timeline of white dwarfs, neutron stars, and supernovae ;Other *1 E12 s *Background (disambiguation) *Holmdel Township, New Jersey |} ==Bibliography== *Seife, Charles (2003). Breakthrough of the Year: Illuminating the Dark Universe. ''Science'' 302 2038–2039. *Partridge, R. B. (1995). ''3K: The Cosmic Microwave Background Radiation''. New York: Cambridge University Press. *R. A. Alpher and R. Herman, "On the Relative Abundance of the Elements," ''Physical Review'' 74 (1948), 1577. This paper contains the first estimate of the present temperature of the universe. *A. A. Penzias and R. W. Wilson, "A Measurement of Excess Antenna Temperature at 4080 Mc/s," ''Astrophysics Journal'' 142 (1965), 419. The paper describing the discovery of the cosmic microwave background. *R. H. Dicke, P. J. E. Peebles, P. G. Roll and D. T. Wilkinson, "Cosmic Black-Body Radiation," ''Astrophysics Journal'' 142 (1965), 414. The theoretical interpretation of Penzias and Wilson's discovery. ==References and external links== * [http://lambda.gsfc.nasa.gov/ NASA's data center for Cosmic Microwave Background (CMB)] * Weisstein, E. W., "''[http://scienceworld.wolfram.com/physics/CosmicBackgroundRadiation.html Cosmic Background Radiation]''". * GSU hyperphysics's "''[http://hyperphysics.phy-astr.gsu.edu/hbase/bkg3k.html 3K Cosmic Background Radiation]''". * Wilson, Robert Woodrow, "''[http://www.nobel.se/physics/laureates/1978/wilson-lecture.html The Cosmic Microwave Background Radiation]''". Nobel Lecture. * Wilkinson Microwave Anisotropy Probe (WMAP) [http://map.gsfc.nasa.gov/ Project ]. [ed. ''full-sky map of the oldest detected electromagnetic energy in the universe]'' -- [http://map.gsfc.nasa.gov/m_uni/uni_101bbtest3.html Tests of the Big Bang: The CMB] * [http://aether.lbl.gov/www/projects/cobe/ COsmic Background Explorer] : NASA's COBE (Cosmic Background Explorer) satellite. * Hu, Wayne, "''[http://background.uchicago.edu/~whu/beginners/introduction.html Introduction to the Cosmic Microwave Background].''" Public talk presented at the IAS. * Cosmic Background Imager (CBI) [http://www.astro.caltech.edu/~tjp/CBI/ Project] * Boomerang (Stratospheric Balloon Borne Telescope) [http://boom.caltech.edu/ Boomerang] * [http://www.archeops.org/index_english.html Archeops] (Planck HFI instrument on balloon test) * [http://aether.lbl.gov/www/ CMB Astrophysics Research Program] -- [http://aether.lbl.gov/www/science/cmb.html Cosmic Microwave Background Radiation] * Dept. Physics & Astronomy, "''[http://csep10.phys.utk.edu/astr162/lect/cosmology/cbr.html Cosmic Background Radiation]''". Astronomy 162. University of Tennessee. * [http://physics.hallym.ac.kr/education/stellar/MAP/Default.html MAP Project]. "''[http://physics.hallym.ac.kr/education/stellar/MAP/html/fluct.html Fluctuations in the Cosmic Microwave Background]''". Department of Physics, Hallym University. * CMB and Large Scale Structure -- "''[http://www-ctp.mit.edu/cosmo/oneday/speaker.html One Day Cosmology Meeting]''". Massachusetts Institute of Technology, April 4, 1997. Astrophysics Cosmology
I moved here the contents of CBR because the term is more general that the CMBR, that this article describes. --:AN I'm starting some discussion on Talk:Sunyaev-Zeldovich effect which relates to recent changes and reversions of Cosmic microwave background radiation as well. If anyone watching here has anything to say on the relevance of the Dirac sea to the SZ effect please take a look. --User:EddEdmondson 09:45, 25 Mar 2004 (UTC) == Reionization Period? == I'd like to see discussion either here or at reionization about how the reionization period related to the CMB. --User:Zandperl 03:56, 9 Jul 2004 (UTC) ----- No it doesn't.... === WMAP data reviewed (early 2004), casts doubt on anisotropy === See [http://www.ras.org.uk/html/press/pn0401ras.html here] for a recent reappriasal of the WMAP data by Professor Tom Shanks of the University of Durham that casts some doubt on some of the anisotropic evidence. ==Confusing== The line: "During the mid-1990s, the lack of detection of anisotropies in the CMB led to some interest in nonstandard cosmologies (such as plasma cosmology) mostly as a backup in case detectors failed to find anisotropy in the CMB. The discovery of these anisotropies combined with a large amount of new data coming in has greatly reduced interest in these alternative theories" ....does not make sense. During the mid 90's? Didn't we know about anisotropy since COBE's results in early 1992?--User:Deglr6328 04:59, 27 Dec 2004 (UTC) ==CMB prediction== I thought the CMB was predicted long before George Gamow, Ralph Alpher, and Robert Hermann in the 1940s, as follows: * 1926: Sir Arthur Eddington estimates the thermal background radiation temperature as 3.2K. * 1930s: Cosmologist Ernst Regener calculates that intergalactic space has a background temperature of 2.8K * 1938: Nobel Prize winner (1920) Walther Nernst estimates 0.75K * 1946: Robert Dicke predicts an MBR (microwave background radiation) temperature of 20K (ref: Helge Kragh) * 1946: Robert Dicke predicts an MBR temperature of "less that 20K" but later revised to 45K (ref: Stephen G. Brush) * 1946: Gamow estimates a temperature of 50K * 1948: Ralph Alpher and Robert Herman re-estimate Gamow's estimate at 5K. * 1949: Ralph Alpher and Robert Herman re-re-estimate Gamow's estimate at 28K. * 1960s: Robert Dicke re-estimates a MBR (microwave background radiation) temperature of 40K (ref: Helge Kragh) == "Large-scale structure of the cosmos" category == Should this article be placed in the "Large-scale structure of the cosmos" category? —User:Vespristiano 02:50, 8 Jan 2005 (UTC) == Style, coordination == As a lot of other cosmology related articles, this article has a very large "See also" list. I'd to propose trimming this down: * Don't link to articles which are already linked in the prose. * Don't link to articles, which are not centrally related. They can be reached via the category. What's the opinion of the other contributors? Also, I'd like to ask, whether it would make sense and find interest contributors, to set up a "cosmological coordination", a WikiProject to have an eye on consistency, missing and duplicated articles. User:Pjacobi 19:22, 2005 Jan 29 (UTC) == Features Question == Could someone describe how the 700 km/s velocity, described as the basis for the dipole shift in the CMB, was measured/inferred? Is it the inferred velocity of the Local Group that would cause the observed dipole shift? Does this dipole pattern induce a "preferred coordinate system" for the universe? User:Wdanwatts 19:00, 26 Apr 2005 (UTC) It is actually a dipole due to the motion of the Earth wrt the CMB -- that's all components including the motion of the sun through the galaxy and the motion of the galaxy toward the great attractor. It introduces a preferred Galilean reference frame which jives fine with GR since GR just requires Lorentz invariance. The feature looks like a giant hotspot and a giant coldspot on the sky due to the velocity-related redshift. [http://antwrp.gsfc.nasa.gov/apod/ap010128.html See this picture of it].User:Joshuaschroeder 06:27, 15 May 2005 (UTC) :Therefore, shouldn't the CMBR section state that it is consistent with such motion instead of being worded such that it appears to be an independent statement of the galactic motion? Instead of "It is mostly due to the motion of the observer against the CMB, which is some 700 km/s ..." shouldn't it be a more accurate statement such as "This feature is consistent with the observer moving at some 700 km/s relative to the CMB." ? User:Wdanwatts 14:41, 15 May 2005 (UTC) == APOD == Congratulations are in order. This article is linked to NASA's Astronomy Picture of the Day feature for May 8th. http://antwrp.gsfc.nasa.gov/apod/ap050508.html User:Fire Star 05:35, 8 May 2005 (UTC)
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Cosmic_microwave_background_radiation
Cosmic_microwave_background_radiation
Cosmic microwave background radiation
[[Image:WMAP.jpg|thumb|rightt|300px|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. It has the characteristics of black body radiation at a temperature of 1 E0 K. It has a frequency in the microwave range. ==CMB and the Big Bang== This radiation is regarded as the best available evidence of the Big Bang (BB) theory and its discovery in the mid-1960s curtailed interest for non-standard cosmology such as the steady state theory. The CMB gives a snapshot of the Universe when, according to standard cosmology, the temperature dropped enough to allow electrons and protons to form hydrogen atoms, thus making the universe transparent to radiation. When it originated some 1 E12 s after the Big Bang -- this time period is generally known as the "time of last scattering" or the period of recombination or decoupling -- the temperature of the Universe was about 1 E3 K. Since then the temperature of the radiation has dropped by a factor of roughly 1 E3 due to the expansion of the Universe. As the universe expands, the CMB photons are redshifted, cooling the radiation inversely proportional to the Universe's Scale factor (Universe). For details on reasoning that the radiation is used as evidence of the Big Bang, see Big Bang#Cosmic_microwave_background_radiation. After the creation of the CMB, there are a number of important events. The CMB created hydrogen atoms, but from observations of galaxies, it seems that most of the intergalactic medium consists of ionized material (since there are few absorption lines due to hydrogen atoms). This implies a period of reionization in which the material of the universe breaks down into hydrogen ions. The favored explanation for this is that starlight causes reionization although there is evidence that reionization began before there were large numbers of stars. The period after the emission of the CMB and the observation of the first stars is semi-humorously referred to by cosmologists as the dark age, and is a period which is under intense study by astronomers. [[Image:WMAP power spectrum.jpg|thumb|right|350px|The power spectrum of the cosmic microwave background radiation anisotropy in terms of the multipole moment (top). Data from WMAP have extended the accuracy of the spectrum far beyond what was known from earlier measurements.]] ==Features== One feature of the CMB is how closely it matches a black body. Although the temperature of the CMB varies from point to point (i.e. it contains small anisotropies), the spectrum in a particular direction very closely resembles a black body. Another of the microwave background's salient features is a high degree of isotropic. There are however some Anisotropic as well, the most pronounced of which is the dipole anisotropy (180 degree scales) which is at a level of about 10 −3 of the monopole. This feature is consistent with the Earth moving at some 700 km/s relative to the CMB. Variations due to external physics also exist; the Sunyaev Zeldovic Effect is one of the major factors here, in which a cloud of high energy electrons scatters the radiation, transferring some energy to the CMB photons. Even more interesting are anisotropy at a level of roughly 10 −5 on scales of roughly tens of arcminutes to several degrees. These very small variations are the result of the Sachs-Wolfe effect which causes photons from the cosmic microwave background to be gravitationally redshifted. According to cosmic inflation, the origin of the variations is quantum fluctuations which expand during inflation and result in primordial fluctuations. The angular power spectrum of these variations (in terms of amplitudes of component multipole moments) can be calculated and produces a number of peaks and valleys. The location of these peaks and valleys can be correlated with cosmological parameters such as the Hubble constant, and the shape of the universe. ==Detection, prediction and discovery== ''Main article:'' Discovery of cosmic microwave background radiation The CMB was predicted by George Gamow, Ralph Alpher, and Robert Hermann in the 1940s and was accidentally discovered in 1964 by Arno Penzias and Robert Woodrow Wilson, who received a Nobel Prize in Physics in 1978 for this discovery. The interpretation of the CMB was a very controversial issue in the 1960s with some proponents of the steady state theory arguing that the CMB was the result of scattered starlight from distant galaxies. Using this model, and based on the study of narrow absorption line features in the spectra of stars, the astronomer Andrew McKellar wrote in 1941: "It can be calculated that the 'rotational' temperature of interstellar space is 2 K." However, during the 1970s the consensus view moved to the point of view that the CBR was the remnant of the big bang. Among the observations that swung the astronomical community toward this point of view were the fact that the CBR was much smoother than would be expected from scattered star light. Because water absorbs microwave radiation, a fact that is used to build microwave ovens, it is rather difficult to observe the CMB with ground-based instruments. CMB research therefore makes increasing use of air and space-borne experiments. Ground-based observations of the CMB are usually made from high altitude locations such as the Andes and the South Pole. ==Experiments== Of these experiments, the Cosmic Background Explorer (COBE) satellite that was flown in 1989-1996 is probably the most famous and which made the first detection of the large scale anisotropies (other than the dipole). Inspired by the COBE results, a series of ground and balloon-based experiments measured CMB anisotropies on smaller angular scales over the next decade. The primary goal of these experiments was to measure the scale of the first acoustic peak, which COBE did not have sufficient resolution to resolve. These measurements were able to rule out cosmic strings as a theory of cosmic structure formation, and suggested cosmic inflation was the right theory. The first peak was measured with increasing sensitivity and by 2000 the Boomerang experiment reported that the highest power fluctions occur at one degree scales. Together with other cosmological data, these results implied that the geometry of the Universe is flat space. A number of ground-based interferometer provided measurements of the fluctuations with higher accuracy over the next three years, including the Very Small Array and the Cosmic Background Imager. In June 2001, NASA launched a second CBR space mission, WMAP, to make much more accurate measurements of the large scale anisotropies over the full sky. Results from this mission disclosed in 2003 provided a detailed measurement of the angular power spectrum down to degree scales, tightly constraining various cosmological parameters. The results are broadly consistent with those expected from cosmic inflation as well as various other competing theories, and are available in detail at NASA's data center for Cosmic Microwave Background (CMB) [''ed.'' see links below]. Although WMAP provided very accurate measurements of the large angular-scale fluctuations in the CMB (structures about as large in the sky as the moon), it did not have the angular resolution to measure the small scale fluctuations which had been observed using previous ground-based interferometer. A third space mission, the Planck Surveyor, is to be launched in 2007. Planck employs bolometer technology and will measure the CMB on smaller scales than WMAP. Unlike the previous two space missions, Planck is a collaboration between NASA and European Space Agency (the European Space Agency). Its detectors got a trial run at the Antarctic Viper telescope as ACBAR (Arcminute Cosmology Bolometer Array Receiver) experiment, which gave the currently most precise measurements at high ''l'', and at the Archeops balloon telescope. Additional ground-based instruments such as CLOVER array in Antarctica will provide additional data not available from satellite observations, such as the B-mode polarization component. === List of experiments in approximate chronological order === Each experiment provided improved data quality when compared with previous experiments. * COBE - measured the very large scale fluctuations * Cosmic Anisotropy Telescope - measured the very small scale fluctuations in small regions of the sky * Maxima - measured intermediate scale fluctuations with improved precision * Boomerang experiment - measured intermediate scale fluctuations with improved precision * Cosmic Background Imager - measured the very small scale fluctuations with improved precision in small regions of the sky * Very Small Array - measured intermediate and small scale fluctuations with improved precision in small regions of the sky * WMAP - measured intermediate and large scale fluctuations with improved precision * Arcminute Cosmology Bolometer Array Receiver - measured intermediate and small scale fluctuations with improved precision * CLOVER array - (2008?) - improved precision for small scale fluctuations and B-mode polarization measurements * Planck (satellite) - (2009?) - will give improved precision at all scales ==See also== {|cellpadding="5" |valign="top"| ;Main *Background radiation *COBE *Cosmic inflation *Cosmic background radiation *Gravitational radiations *Microwave *Unsolved problems in physics *WMAP ;Physics and Astronomy *Anisotropy (or Anisotropic) *Baryonic dark matter *Big bang nucleosynthesis, *Black body *Black dwarf *Cold dark matter *Dark energy *Greisen-Zatsepin-Kuzmin limit *History of astronomy *Hubble's law *Integrated Sachs Wolfe effect *Nobel Prize in Physics *Observation *Olbers' paradox *Radio astronomy *Redshift |valign="top"| *Big Bang *Big Crunch ;People *Arno Allan Penzias *Fred Hoyle *Georges Lemaître *Robert Wilson *Robert Woodrow Wilson ;Timelines and lists *List of astronomical topics *List of famous experiments *Timeline of cosmic microwave background astronomy *Timeline of knowledge about galaxies, clusters of galaxies, and large-scale structure *Timeline of the Big Bang *Timeline of white dwarfs, neutron stars, and supernovae ;Other *1 E12 s *Background (disambiguation) *Holmdel Township, New Jersey |} ==Bibliography== *Seife, Charles (2003). Breakthrough of the Year: Illuminating the Dark Universe. ''Science'' 302 2038–2039. *Partridge, R. B. (1995). ''3K: The Cosmic Microwave Background Radiation''. New York: Cambridge University Press. *R. A. Alpher and R. Herman, "On the Relative Abundance of the Elements," ''Physical Review'' 74 (1948), 1577. This paper contains the first estimate of the present temperature of the universe. *A. A. Penzias and R. W. Wilson, "A Measurement of Excess Antenna Temperature at 4080 Mc/s," ''Astrophysics Journal'' 142 (1965), 419. The paper describing the discovery of the cosmic microwave background. *R. H. Dicke, P. J. E. Peebles, P. G. Roll and D. T. Wilkinson, "Cosmic Black-Body Radiation," ''Astrophysics Journal'' 142 (1965), 414. The theoretical interpretation of Penzias and Wilson's discovery. ==References and external links== * [http://lambda.gsfc.nasa.gov/ NASA's data center for Cosmic Microwave Background (CMB)] * Weisstein, E. W., "''[http://scienceworld.wolfram.com/physics/CosmicBackgroundRadiation.html Cosmic Background Radiation]''". * GSU hyperphysics's "''[http://hyperphysics.phy-astr.gsu.edu/hbase/bkg3k.html 3K Cosmic Background Radiation]''". * Wilson, Robert Woodrow, "''[http://www.nobel.se/physics/laureates/1978/wilson-lecture.html The Cosmic Microwave Background Radiation]''". Nobel Lecture. * Wilkinson Microwave Anisotropy Probe (WMAP) [http://map.gsfc.nasa.gov/ Project ]. [ed. ''full-sky map of the oldest detected electromagnetic energy in the universe]'' -- [http://map.gsfc.nasa.gov/m_uni/uni_101bbtest3.html Tests of the Big Bang: The CMB] * [http://aether.lbl.gov/www/projects/cobe/ COsmic Background Explorer] : NASA's COBE (Cosmic Background Explorer) satellite. * Hu, Wayne, "''[http://background.uchicago.edu/~whu/beginners/introduction.html Introduction to the Cosmic Microwave Background].''" Public talk presented at the IAS. * Cosmic Background Imager (CBI) [http://www.astro.caltech.edu/~tjp/CBI/ Project] * Boomerang (Stratospheric Balloon Borne Telescope) [http://boom.caltech.edu/ Boomerang] * [http://www.archeops.org/index_english.html Archeops] (Planck HFI instrument on balloon test) * [http://aether.lbl.gov/www/ CMB Astrophysics Research Program] -- [http://aether.lbl.gov/www/science/cmb.html Cosmic Microwave Background Radiation] * Dept. Physics & Astronomy, "''[http://csep10.phys.utk.edu/astr162/lect/cosmology/cbr.html Cosmic Background Radiation]''". Astronomy 162. University of Tennessee. * [http://physics.hallym.ac.kr/education/stellar/MAP/Default.html MAP Project]. "''[http://physics.hallym.ac.kr/education/stellar/MAP/html/fluct.html Fluctuations in the Cosmic Microwave Background]''". Department of Physics, Hallym University. * CMB and Large Scale Structure -- "''[http://www-ctp.mit.edu/cosmo/oneday/speaker.html One Day Cosmology Meeting]''". Massachusetts Institute of Technology, April 4, 1997. Astrophysics Cosmology
Cosmic microwave background radiation
I moved here the contents of CBR because the term is more general that the CMBR, that this article describes. --:AN I'm starting some discussion on Talk:Sunyaev-Zeldovich effect which relates to recent changes and reversions of Cosmic microwave background radiation as well. If anyone watching here has anything to say on the relevance of the Dirac sea to the SZ effect please take a look. --User:EddEdmondson 09:45, 25 Mar 2004 (UTC) == Reionization Period? == I'd like to see discussion either here or at reionization about how the reionization period related to the CMB. --User:Zandperl 03:56, 9 Jul 2004 (UTC) ----- No it doesn't.... === WMAP data reviewed (early 2004), casts doubt on anisotropy === See [http://www.ras.org.uk/html/press/pn0401ras.html here] for a recent reappriasal of the WMAP data by Professor Tom Shanks of the University of Durham that casts some doubt on some of the anisotropic evidence. ==Confusing== The line: "During the mid-1990s, the lack of detection of anisotropies in the CMB led to some interest in nonstandard cosmologies (such as plasma cosmology) mostly as a backup in case detectors failed to find anisotropy in the CMB. The discovery of these anisotropies combined with a large amount of new data coming in has greatly reduced interest in these alternative theories" ....does not make sense. During the mid 90's? Didn't we know about anisotropy since COBE's results in early 1992?--User:Deglr6328 04:59, 27 Dec 2004 (UTC) ==CMB prediction== I thought the CMB was predicted long before George Gamow, Ralph Alpher, and Robert Hermann in the 1940s, as follows: * 1926: Sir Arthur Eddington estimates the thermal background radiation temperature as 3.2K. * 1930s: Cosmologist Ernst Regener calculates that intergalactic space has a background temperature of 2.8K * 1938: Nobel Prize winner (1920) Walther Nernst estimates 0.75K * 1946: Robert Dicke predicts an MBR (microwave background radiation) temperature of 20K (ref: Helge Kragh) * 1946: Robert Dicke predicts an MBR temperature of "less that 20K" but later revised to 45K (ref: Stephen G. Brush) * 1946: Gamow estimates a temperature of 50K * 1948: Ralph Alpher and Robert Herman re-estimate Gamow's estimate at 5K. * 1949: Ralph Alpher and Robert Herman re-re-estimate Gamow's estimate at 28K. * 1960s: Robert Dicke re-estimates a MBR (microwave background radiation) temperature of 40K (ref: Helge Kragh) == "Large-scale structure of the cosmos" category == Should this article be placed in the "Large-scale structure of the cosmos" category? —User:Vespristiano 02:50, 8 Jan 2005 (UTC) == Style, coordination == As a lot of other cosmology related articles, this article has a very large "See also" list. I'd to propose trimming this down: * Don't link to articles which are already linked in the prose. * Don't link to articles, which are not centrally related. They can be reached via the category. What's the opinion of the other contributors? Also, I'd like to ask, whether it would make sense and find interest contributors, to set up a "cosmological coordination", a WikiProject to have an eye on consistency, missing and duplicated articles. User:Pjacobi 19:22, 2005 Jan 29 (UTC) == Features Question == Could someone describe how the 700 km/s velocity, described as the basis for the dipole shift in the CMB, was measured/inferred? Is it the inferred velocity of the Local Group that would cause the observed dipole shift? Does this dipole pattern induce a "preferred coordinate system" for the universe? User:Wdanwatts 19:00, 26 Apr 2005 (UTC) It is actually a dipole due to the motion of the Earth wrt the CMB -- that's all components including the motion of the sun through the galaxy and the motion of the galaxy toward the great attractor. It introduces a preferred Galilean reference frame which jives fine with GR since GR just requires Lorentz invariance. The feature looks like a giant hotspot and a giant coldspot on the sky due to the velocity-related redshift. [http://antwrp.gsfc.nasa.gov/apod/ap010128.html See this picture of it].User:Joshuaschroeder 06:27, 15 May 2005 (UTC) :Therefore, shouldn't the CMBR section state that it is consistent with such motion instead of being worded such that it appears to be an independent statement of the galactic motion? Instead of "It is mostly due to the motion of the observer against the CMB, which is some 700 km/s ..." shouldn't it be a more accurate statement such as "This feature is consistent with the observer moving at some 700 km/s relative to the CMB." ? User:Wdanwatts 14:41, 15 May 2005 (UTC) == APOD == Congratulations are in order. This article is linked to NASA's Astronomy Picture of the Day feature for May 8th. http://antwrp.gsfc.nasa.gov/apod/ap050508.html User:Fire Star 05:35, 8 May 2005 (UTC)
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C
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Cosmic_microwave_background_radiation
Cosmic_microwave_background_radiation
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