| electromagnetic radiation coming from every direction in the universe, considered the remnant of the big bang and corresponding to the black-body radiation of 3 K, the temperature to which the universe has cooled. |
The microwave radiation that arrives at the Earth from every direction in space. The detection of this radiation played an important role in acceptance of the Big Bang theory.
Note: This radiation is sometimes referred to as the “echo” of the Big Bang.
| cosmic background radiation
Weak radio-frequency radiation traveling through outer space with equal intensity in every direction. It is thought to be residual radiation from a period shortly following the big bang, when the universe was very hot. Also called microwave background. |