Timeline of cosmic microwave background astronomy
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2008-06-13T02:09:22Z
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'''[[Timeline]] of [[cosmic microwave background]] [[astronomy]]'''
===Thermal (non-microwave background) temperature predictions===
* [[1896]] - [[Charles Edouard Guillaume]] estimates the "radiation of the stars" to be 5.6[[Kelvin|K]].<ref>Guillaume, C.-E., 1896, ''La Nature'' 24, series 2, p. 234, cited in [http://redshift.vif.com/JournalFiles/Pre2001/V02NO3PDF/V02N3ASS.PDF "History of the 2.7 K Temperature Prior to Penzias and Wilson" (PDF)]</ref>
* [[1926]] - Sir [[Arthur Eddington]] estimates the non-thermal radiation of [[starlight]] in the galaxy ".. by the formula E = σT<sup>4</sup> the effective temperature corresponding to this density is 3.18º absolute .. black body"<ref>Eddington, A., [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1927Sci....66...81E&db_key=AST&data_type=HTML&format=&high=42ca922c9c22437 The Internal Constitution of the Stars], cited in [http://redshift.vif.com/JournalFiles/Pre2001/V02NO3PDF/V02N3ASS.PDF "History of the 2.7 K Temperature Prior to Penzias and Wilson" (PDF)]</ref>
* [[1930s]] - [[Cosmologist]] [[Erich Regener]] calculates that the non-thermal spectrum of cosmic rays in the galaxy has an effective temperature of 2.8K
* [[1931]] - Term ''microwave'' first used in print: "When trials with wavelengths as low as 18 cm. were made known, there was undisguised surprise+that the problem of the micro-wave had been solved so soon." Telegraph & Telephone Journal XVII. 179/1
* [[1934]] - [[Richard Tolman]] shows that [[black-body]] radiation in an expanding universe cools but remains thermal
* [[1938]] - Nobel Prize winner (1920) [[Walther Nernst]] reestimates the cosmic ray temperature as 0.75K
* [[1941]] - [[Andrew McKellar]] uses the excitation of CN doublet lines to measure that the "effective temperature of space" is about 2.3 [[Kelvin|K]]
* [[1946]] - [[Robert Dicke]] predicts ".. radiation from cosmic matter" at <20 K, but did not refer to background radiation <ref name=Kragh>Helge Kragh, Cosmology and Controversy: [http://books.google.com/books?id=f6p0AFgzeMsC&vid=ISBN069100546X&pg=PA135&lpg=PA135&sig=h6snxSfYc8zr3aoxiu-WbOJgpvk&q=cosmic+microwave The Historical Development of Two Theories of the Universe] (1999) ISBN 0-691-00546-X. "In 1946 Robert Dicke and coworkers at MIT tested equipment that could test a cosmic microwave background of intensity corresponding to about 20K in the microwave region. However, they did not refer to such a background, but only to 'radiation from cosmic matter'. Also this work was unreleated to cosmology, and is only mentioned because it suggests that by 1950 detection of the background radiation might have been technically possible, and also because of Dicke's later role in the discovery". See also Robert H. Dicke, Robert Beringer, Robert L. Kyhl, and A. B. Vane, "[http://prola.aps.org/abstract/PR/v70/i5-6/p340_1 Atmospheric Absorption Measurements with a Microwave Radiometer]" (1946) ''Phys. Rev''. 70, 340–348</ref>
* [[1946]] - [[George Gamow]] calculates a temperature of 50 K (assuming a 3-billion year old Universe)<ref>George Gamow, ''[http://books.google.com/books?id=5awirwgmvAoC&pg=PA40&lpg=PA40&vq=50&dq=%22creation+of+the+universe%22+gamow&sig=cnNpSmeBqcMg7dnA4ImfKjiLNE0 The Creation Of The Universe]'' p.50 (Dover reprint of revised 1961 edition) ISBN 0-486-43868-6</ref>, commenting it ".. is in reasonable agreement with the actual temperature of interstellar space", but does not mention background radiation.
* [[1953]] - [[Erwin Finlay-Freundlich]] in support of his [[tired light]] theory, derives a blackbody temperature for intergalactic space of 2.3K <ref>Erwin Finlay-Freundlich, "[http://adsabs.harvard.edu/abs/1953CoStA...4...96F Ueber die Rotverschiebung der Spektrallinien]" (1953) ''Contributions from the Observatory, University of St. Andrews'' ; no. 4, p. 96-102. Finlay-Freundlich also gave two extreme values of 1.9K and 6.0K in Finlay-Freundlich, E.: 1954, "Red shifts in the spectra of celestial bodies", Phil. Mag., Vol. 45, pp. 303-319.</ref> with comment from [[Max Born]] suggesting radio astronomy as the arbitrator between expanding and infinite cosmologies.
=== Microwave background radiation predictions ===
* [[1946]] - [[George Gamow]] calculates a temperature of 50 K (assuming a 3-billion year old Universe)<ref>George Gamow, ''[http://books.google.com/books?id=5awirwgmvAoC&pg=PA40&lpg=PA40&vq=50&dq=%22creation+of+the+universe%22+gamow&sig=cnNpSmeBqcMg7dnA4ImfKjiLNE0 The Creation Of The Universe]'' p.50 (Dover reprint of revised 1961 edition) ISBN 0-486-43868-6</ref>, commenting it ".. is in reasonable agreement with the actual temperature of interstellar space", but does not mention background radiation.
* [[1948]] - [[Ralph Alpher]] and [[Robert Herman]] estimate "the temperature in the Universe" at 5 K. Although they do not specifically mention microwave background radiation, it may be inferred.<ref>Helge Kragh, Cosmology and Controversy: [http://books.google.com/books?vid=ISBN069100546X&id=f6p0AFgzeMsC&pg=PA132&lpg=PA132&vq=cosmic+microwave&sig=YvmlZ13jwKPS0ucC5ogFsPqwfnY The Historical Development of Two Theories of the Universe] (1999) ISBN 0-691-00546-X. "Alpher and Herman first calculated the present temperature of the decoupled primordial radiation in 1948, when they reported a value of 5 K. Although it was not mentioned either then or in later publications that the radiation is in the microwave region, this follows immediately from the temperature .. Alpher and Herman made it clear that what they had called "the temperature in the univerese" the previous year referred to a blackbody distributed background radiation quite different from sunliight".</ref>
* [[1949]] - Ralph Alpher and Robert Herman re-re-estimate the temperature at 28 K.
* [[1957]] - Tigran Shmaonov reports that "the absolute effective temperature of the radioeission background ... is 4+/- 3K"<ref>Tigran Shmaonov, ''Pribory i Teknika Eksperienta'' (1957)</ref>. It is noted that the "measurements showed that radiation intensity was independent of either time or direction of observation .. it is now clear that Shmaonov did observe the cosmic microwave background at a wavelength of 3.2cm"<ref>Dmitri I. Novikov, The Physics of the Cosmic Microwave Background, 2006, Cambridge University Press, 272 pages, ISBN 0521855500. ([http://books.google.com/books?hl=en&lr=&id=J2KCisZsWZ0C&oi=fnd&pg=RA1-PA1&dq=Shmaonov+cmb&ots=JBjbEu7tNl&sig=JgZNDEsD8ULPUv4WI8my3IZED1U#PRA1-PA5,M1 page 5])</ref>
* [[1960]]s - [[Robert Dicke]] re-estimates a microwave background radiation temperature of 40K (ref: Helge Kragh)
* [[1964]] - [[A. G. Doroshkevich]] and [[Igor Dmitrievich Novikov]] write an unnoticed paper suggesting microwave searches for the black-body radiation predicted by Gamow, Alpher, and Herman.<ref>A. G. Doroshkevich and I. D. Novikov, "[http://adsabs.harvard.edu/abs/1964SPhD....9..111D Mean Density of Radiation in the Metagalaxy and Certain Problems in Relativistic Cosmology]" ''Sov. Phys. Doklady'' 9, 111 (1964).</ref>
* [[1965]] - [[Arno Penzias]], [[Robert Woodrow Wilson|Robert Wilson]], [[Bernie Burke]], [[Robert Dicke]], and [[Philip James Edwin Peebles|James Peebles]] discover the cosmic microwave background radiation, eventually confirmed at approximately 2.7K
* [[1966]] - [[Rainer Sachs]] and [[Arthur Michael Wolfe]] theoretically predict microwave background fluctuation amplitudes created by [[gravitational potential]] variations between observers and the last scattering surface (see [[Sachs-Wolfe effect]])
* [[1968]] - [[Martin Rees]] and [[Dennis Sciama]] theoretically predict microwave background fluctuation amplitudes created by photons traversing time-dependent potential wells
* [[1969]] - [[R. A. Sunyaev]] and [[Yakov Zel'dovich]] study the inverse [[Compton scattering]] of microwave background photons by hot electrons (see [[Sunyaev-Zel'dovich effect]])
* [[1983]] - Researchers from the [[Cavendish Astrophysics Group|Cambridge Radio Astronomy Group]] and the [[Owens Valley Radio Observatory]] first detect the [[Sunyaev-Zel'dovich effect]] from [[galaxy cluster|clusters of galaxies]]
* [[1990]] - The [[Cosmic Background Explorer]] ([[COBE]]) satellite shows that the microwave background has a nearly perfect black-body spectrum and thereby strongly constrains the density of the [[intergalactic medium]].
* January [[1992]] - scientists that analysed data from the [[RELIKT-1]] report the discovery of [[anisotropy]] in the cosmic microwave background at the Moscow astrophysical seminar.<ref>''Nobel Prize In Physics: Russia's Missed Opportunities]'', [[RIA Novosti]], Nov 21, 2006</ref>
* [[1992]] - scientists that analysed data from [[COBE]] report the discovery of [[anisotropy]] in the cosmic microwave background.
* [[1995]] - The [[Cosmic Anisotropy Telescope]] performs the first high resolution observations of the cosmic microwave background.
* [[1999]] - The [[BOOMERanG experiment]] makes higher quality maps at intermediate resolution, and confirms that the Universe is "flat".
* [[2003]] - The [[Cosmic Background Imager | CBI]] and the [[Very Small Array]] produces yet higher quality maps at high resolution (covering small areas of the sky).
* [[2003]] - The [[WMAP]] satellite produces an even higher quality map at low and intermediate resolution of the whole sky (WMAP provides ''no'' high-resolution data, but improves on the intermediate resolution maps from [[BOOMERanG experiment|BOOMERanG]]).
* [[2004]] - E-mode polarization spectrum obtained by the [[Cosmic Background Imager | CBI]].<ref>A. Readhead et al., "Polarization observations with the Cosmic Background Imager", Science 306, 836-844 (2004).</ref>
* [[2004]] - The [[Arcminute Cosmology Bolometer Array Receiver]] produces a higher quality map of the high resolution structure not mapped by WMAP.
* [[2005]] - The [[Arcminute Microkelvin Imager]] and the [[Sunyaev-Zel'dovich Array]] begin the first surveys for very high redshift [[galaxy cluster|clusters of galaxies]] using the [[Sunyaev-Zel'dovich effect]].
=== Future ===
* [[2008]] The [[Clover (telescope)|Clover]] Project will give an improved precision intermediate and high resolution map, and measure the B-mode polarization
* [[2009]] The [[Planck (satellite)]] will give improved precision at all resolutions
== Notes ==
{{Reflist}}
[[Category:Astronomy timelines|Cosmic microwave background astronomy]]