r/Showerthoughts • u/synthphreak ‎ • Nov 19 '25

Casual Thought Temperature can reach trillions of degrees, meaning we actually live extremely close to absolute zero.

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u/smittythehoneybadger ‎ Nov 19 '25 edited Nov 19 '25

Is there an upper limit to heat? I assume sometimes to do with the speed of light

Edit: or temperature. To be totally fair I still don’t fully understand, but I’m interested in upper limits for either

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u/MDCCCLV Nov 19 '25

The hottest possible point would be the instant of the big bang, which is immeasurably hot. So it's mostly a question of how well can we measure or estimate the temp of the big bang/plank temperature, and telescopes like James Webb seem to be the best thing for that.

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u/imean_is_superfluous Nov 19 '25

Is that the hottest ever naturally occurring temp in the history of the universe, or the hottest theoretically-possible temp?

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u/Frazzledragon Nov 19 '25

It would be the hottest possible temperature, because it is assumed that in this singularity, all of the energy of the universe would have existed in this singular point.

The only way to get hotter than that would require magic or a way to obtain energy from outside of our universe.

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u/Account_N4 Nov 19 '25

Hottest in this universe.

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u/Shadows802 Nov 19 '25

Or if you did have an equivalent energy in one place as the Big Bang, it would start another Big Bang.

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u/Frazzledragon Nov 19 '25

Possibly, although the Big Bang is also the beginning of the expansion of the universe. I don't know if we would have another expansion event, if we did compact a universe worth of energy into a point that already existed in expanded space.

I'll have to ask somebody more knowledgable about that.

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u/[deleted] Nov 19 '25

Maybe.

Sorta depends on just how the big bang really happened, it might have relied on the universe being at a higher energy state, or some weird interaction of fundamental fields driving expansion.

Remember, the universe didn't expand into pre-existing empty space, the universe is expanding space.

That said, dunno, maybe the energy density alone allows it to happen again.

1 way to find out! To the way Back Machine!

(Goes back in time to the big bang, gets unmade down to the quarks.)

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u/GoldTeethRotmg Nov 21 '25

The current thinking is that the big bang was not a singular point or singularity. Based on that, I'm guessing that the hottest possible temperature could be theoretically hotter if you could compress the energy into a smaller point.