# Did the Universe have a temperature at t=0?

**URL:** <https://boards.straightdope.com/t/did-the-universe-have-a-temperature-at-t-0/927979>\
**Category:** Factual Questions\
**Created:** [December 14, 2020, 3:41am UTC](https://boards.straightdope.com/t/did-the-universe-have-a-temperature-at-t-0/927979 "2020-12-14T03:41:58Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\
**Post date:** [December 14, 2020, 3:41am UTC](https://boards.straightdope.com/t/did-the-universe-have-a-temperature-at-t-0/927979/1 "2020-12-14T03:41:58Z")

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I understand that it is debated if the Universe started from zero entropy or not.

Does that mean:  
A. The Universe had a temperature at t=0, but we are not sure if it was 0

or

B. We do not know that a metric like temperature applies to the universe at t=0 ?

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [December 14, 2020, 11:52am UTC](https://boards.straightdope.com/t/did-the-universe-have-a-temperature-at-t-0/927979/2 "2020-12-14T11:52:51Z")

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We don’t even know if the Universe had a t=0. And if it did, we know nothing at all about what conditions were like at that moment.

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**Author:** ![FrenchDunadan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frenchdunadan/32/5449_2.png) [@FrenchDunadan](https://boards.straightdope.com/u/FrenchDunadan)\
**Post date:** [December 14, 2020, 7:17pm UTC](https://boards.straightdope.com/t/did-the-universe-have-a-temperature-at-t-0/927979/3 "2020-12-14T19:17:41Z")

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After about 380 000 years, the temperature dropped below 3 000 K.  
After about 10^-43 s (Planck era) the temperature was about 10^32 K.  
since the evolution is roughly Temp = 1/square root (time)… well if time is =0 then Temp = infinite 😱! ! ! ! Naked Singularity 😨 !  
So we can ponder the temperature shortly after the Big Bang, but not exactly at t=0. And as Chronos said, t=0 is a tricky question…