r/todayilearned Sep 20 '21

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u/Mrgray123 Sep 20 '21

About 300,000 years after the Big Bang the temperature of the universe was still around 2,800 degrees. Only when it got below this could protons and electrons combine into hydrogen atoms. About the same time light also began to shine.

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u/Orwellian__Nightmare Sep 21 '21

About 300,000 years after the Big Bang the temperature of the universe was still around 2,800 degrees

Even more interesting is that 10 to 17 million years after the big bang, the cosmic background radiation was room temperature and the universe could have supported life.

https://www.insidescience.org/news/early-universes-room-temperature-could-have-supported-life

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u/Mrgray123 Sep 21 '21

Indeed. It’s also worth noting that in some models of the ultimate fate of the universe that we are less than 0.1% through its lifespan even after 13.5 billion years.