The cosmic microwave background (CMB) is the universe's oldest light, leftover thermal radiation from about 380,000 years after the big bang. Maps of the CMB offer a picture of the "baby universe" as it was 13.8 billion years ago.
The cosmic microwave background (CMB) is the universe's oldest light, leftover thermal radiation from about 380,000 years after the big bang. Maps of the CMB offer a picture of the "baby universe" as it was 13.8 billion years ago.