In 1965, American physicists Arno Penzias (1933–) and Robert Wilson (1936–) announced the discovery of microwave radiation, which uniformly filled the sky and had a blackbody temperature of about 3.5K. The pair had been testing a new radio amplifier that was supposed to be exceptionally quiet. After many attempts to account for all extraneous sources of radio noise, they concluded that there was a general background of radiation at the radio frequency they were using. After discussions with a group led by Robert Dicke at nearby Princeton University it became clear that they had in fact detected remnant radiation from the origin of the universe.

Although neither Dicke's group nor Penzias and Wilson realized it at the time, they had confirmed a prediction made by scientists 17 years earlier. Although the temperature that characterized the detected radiation was somewhat different than predicted, the difference could be...