| 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. |
| cosmic background radiation n. Faint microwave radiation that penetrates space throughout the universe, postulated to be a residual effect of the Big Bang. |
| Main Entry: | cosmic background radiation |
| Part of Speech: | n |
| Definition: | microwave radiation in the universe, produced during the Big Bang and subsequently thinned and cooled as the universe expanded; also called background radiation |
| Usage: | science |