Q
What is the cosmic microwave background?
A
Expert Answer
The CMB is relic radiation from 380,000 years after the Big Bang, when the universe became transparent to light. It's nearly uniform at 2.7K, with tiny fluctuations that seeded large-scale structure. Its discovery in 1965 provided strong evidence for the Big Bang theory.
Key Insight
The CMB is relic radiation from 380,000 years after the Big Bang, when the universe became transparent to light.
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