search for relics of the Big Bang in the high-wavelength (radio and microwave) region of the spectrum. He had long suspected that hot primordial radiation, cooled over time through cosmological expansion, would be present throughout the cosmos. Along with young astronomers P. J. E. (Jim) Peebles and David Wilkinson, he was developing a radiometer to scan for such remnant signals. They were astonished to learn that they had been beaten to the punch.
The Princeton group quickly calculated the temperature of the radiation that would produce the signals that Penzias and Wilson observed. It turned out to be roughly three degrees Kelvin (three degrees above absolute zero, or minus 454 degrees Fahrenheit). Then, employing techniques in thermal physics, they determined the temperature of a fireball that had been chilled by billions of years of expansion. That value also turned out to be a few degrees Kelvin. Hence, Dicke and his co-workers proclaimed Penzias and Wilson’s findings as proof that the universe was once enormously hot and dense. The low-temperature radiation that fills all of space became known as the cosmic microwave background (CMB).
When Penzias, Wilson, and the Princeton group published these results, they were proclaimed as the most important cosmological discovery since the time of Hubble. In a stunning omission, however, the articles did not cite key work by Gamow, Alpher, and Herman regarding the temperature and content of the early universe. Gamow hurriedly pointed out that he and his colleagues had predicted the relic radiation back in 1948. In his memoirs, Dicke later wrote:
There is one unfortunate and embarrassing aspect of our work on the fireball radiation. We failed to make an adequate literature search and missed the more important papers of Gamow, Alpher and Herman. I must take the major blame for this, for the others in our group were too young to know these old papers. In ancient times I had heard Gamow talk at Princeton but I had remembered his model universe as cold and initially filled only with neutrons.