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Generate QuizThe epoch of recombination, when the universe became transparent to radiation, occurred approximately _______ after the Big Bang.
- 3 minutes
- 380,000 years
- 1 billion years
- 13.8 billion years
Answer: 380,000 years
At ~380,000 years post-Big Bang, electrons combined with protons to form neutral hydrogen, allowing photons to travel freely—this relic radiation is observed today as the CMB.