Editing Observational cosmology (section)

===Detection of the cosmic microwave background===
{{main|Discovery of cosmic microwave background radiation}}
[[File:WMAP 2012.png|thumb|the CMB seen by WMAP]]
A [[cosmic microwave background]] was predicted in 1948 by [[George Gamow]] and [[Ralph Alpher]], and by Alpher and [[Robert Herman]] as due to the hot [[Big Bang]] model. Moreover, Alpher and Herman were able to estimate the temperature,<ref>{{cite journal | last1 = Gamow | first1 = G. | year = 1948 | title = The Origin of Elements and the Separation of Galaxies| journal = Physical Review | volume = 74| issue = 4 | page=505 | doi=10.1103/physrev.74.505.2|bibcode = 1948PhRv...74..505G }}{{cite journal | last1 = Gamow | first1 = G. | title = The evolution of the universe | journal = Nature|volume= 162 | issue = 4122 | pages = 680–2 |year=1948| doi=10.1038/162680a0| pmid = 18893719 |bibcode = 1948Natur.162..680G | s2cid = 4793163 }} {{cite journal | first1= R. A. |last1= Alpher |first2= R. |last2=Herman|title=On the Relative Abundance of the Elements | journal = Physical Review | volume = 74 | issue = 11| page = 1577 | doi=10.1103/physrev.74.1577|bibcode = 1948PhRv...74.1577A |year= 1948 }}</ref> but their results were not widely discussed in the community. Their prediction was rediscovered by [[Robert Dicke]] and [[Yakov Zel'dovich]] in the early 1960s with the first published recognition of the CMB radiation as a detectable phenomenon appeared in a brief paper by [[Soviet Union|Soviet]] astrophysicists [[A. G. Doroshkevich]] and [[Igor Dmitriyevich Novikov|Igor Novikov]], in the spring of 1964.<ref>{{cite journal |author=A. A. Penzias |year=1979 |title=The origin of elements. |url=https://www.nobelprize.org/prizes/physics/1978/penzias/lecture/ |journal=[[Nobel Prize in Physics|Nobel lecture]] |volume=205 |issue=4406 |pages=549–54 |bibcode=1979Sci...205..549P |doi=10.1126/science.205.4406.549 |pmid=17729659 |access-date=October 4, 2006|url-access=subscription }}</ref> In 1964, [[David Todd Wilkinson]] and Peter Roll, Dicke's colleagues at [[Princeton University]], began constructing a Dicke radiometer to measure the cosmic microwave background.<ref>R. H. Dicke, "The measurement of thermal radiation at microwave frequencies", ''Rev. Sci. Instrum.'' '''17''', 268 (1946). This basic design for a radiometer has been used in most subsequent cosmic microwave background experiments.</ref> In 1965, [[Arno Penzias]] and [[Robert Woodrow Wilson]] at the [[Crawford Hill]] location of [[Bell Telephone Laboratories]] in nearby [[Holmdel Township, New Jersey]] had built a Dicke radiometer that they intended to use for radio astronomy and satellite communication experiments. Their instrument had an excess 3.5&nbsp;K [[noise temperature|antenna temperature]] which they could not account for. After receiving a telephone call from Crawford Hill, Dicke famously quipped: "Boys, we've been scooped."<ref>A. A. Penzias and R. W. Wilson, "A Measurement of Excess Antenna Temperature at 4080 Mc/s," ''Astrophysical Journal'' '''142''' (1965), 419. R. H. Dicke, P. J. E. Peebles, P. G. Roll and D. T. Wilkinson, "Cosmic Black-Body Radiation," ''Astrophysical Journal'' '''142''' (1965), 414. The history is given in P. J. E. Peebles, ''Principles of physical cosmology'' (Princeton Univ. Pr., Princeton 1993).</ref> A meeting between the Princeton and Crawford Hill groups determined that the antenna temperature was indeed due to the microwave background. Penzias and Wilson received the 1978 [[Nobel Prize in Physics]] for their discovery.