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The cosmic microwave background was first predicted in 1948 by Ralph Alpher and Robert Herman, in a correction [16] they prepared for a paper by Alpher's PhD advisor George Gamow. [17] Alpher and Herman were able to estimate the temperature of the cosmic microwave background to be 5 K. [18]
1938: Walther Nernst re-estimates the cosmic ray temperature as 0.75 K. [2] 1946: The term "microwave" is first used in print in an astronomical context in an article "Microwave Radiation from the Sun and Moon" by Robert Dicke and Robert Beringer. 1946: Robert Dicke predicts a microwave background radiation temperature of 20 K (ref: Helge Kragh)
Differences in the temperature of the cosmic background are smoothed by cosmic inflation, but they still exist. The theory predicts a spectrum for the anisotropies in the microwave background which is mostly consistent with observations from WMAP and COBE. [6] However, gravity alone may be sufficient to explain this homogeneity. [7]
The discovery of cosmic microwave background radiation constitutes a major development in modern physical cosmology. In 1964, US physicist Arno Allan Penzias and radio-astronomer Robert Woodrow Wilson discovered the cosmic microwave background (CMB), estimating its temperature as 3.5 K, as they experimented with the Holmdel Horn Antenna.
CMB spectral distortions are tiny departures of the average cosmic microwave background (CMB) frequency spectrum from the predictions given by a perfect black body.They can be produced by a number of standard and non-standard processes occurring at the early stages of cosmic history, and therefore allow us to probe the standard picture of cosmology.
The microwave background is a blackbody spectrum representing the photons present at recombination, shifted in energy by the expansion of the universe. A blackbody is completely characterized by its temperature; the shift is called the redshift denoted by z: = (+) where 2.7 K is today's temperature.
The cosmic microwave background spectrum peaks at a frequency of 160.2 GHz. Planck 's passive and active cooling systems allow its instruments to maintain a temperature of −273.05 °C (−459.49 °F), or 0.1 °C above absolute zero . [ 3 ]
The interpretation of the cosmic microwave background was a controversial issue in the late 1960s. Alternative explanations included energy from within the solar system, from galaxies, from intergalactic plasma and from multiple extragalactic radio sources. Two requirements would show that the microwave radiation was truly "cosmic".