Term
Cosmic microwave background
Faint microwave radiation left over from the early universe, arriving from every direction in the sky. One of the main pieces of evidence for the Big Bang theory.
A Short History of Nearly Everything, Bill Bryson
Explained in
- A Short History of Nearly Everything, Bill Bryson
- Astrophysics for People in a Hurry, Neil deGrasse Tyson
The oldest light we can observe. It was set free about 380,000 years after the expansion began, and today it reaches us as faint microwaves.
- Parallel Worlds: A Journey Through Creation, Higher Dimensions, and the Future of the Cosmos, Michio Kaku
Faint microwave radiation that comes from every direction in the sky. It is considered the cooled-down heat of the early universe; it was discovered in 1965.