In 1965, the United States discovered high-temperature microwave radiation coming from the cosmic microwave background (CMB). The CMB is a faint, uniform radiation that permeates throughout the entire universe and is considered to be residual heat from the Big Bang, the event that marked the beginning of the universe.
The discovery of the CMB was a significant milestone in cosmology and provided strong evidence in support of the Big Bang theory. It was detected by the scientists Arno Penzias and Robert Wilson at the Bell Telephone Laboratories in New Jersey, United States. Their work earned them the 1978 Nobel Prize in Physics.