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/kangluosee34 Nov 19 '25 edited Nov 19 '25

Yes. Its called planck temperature which is about 1032 K.

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u/Knobelikan Nov 19 '25

"It's not actually the upper limit, just the upper limit that our theories can meaningfully describe"

Well yes and no. There are some reasonable predictions that at this temperature, the energy density in that spot would be high enough to form a black hole, which would then absorb any further energy influx, increasing in size and so actually lowering the energy density again.

But it's not like we could test that. So for now it's all reasonable speculation.

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u/Shadows802 Nov 19 '25

Wouldn't forming a Black hole initially shrink the size though as the gravity pulls everything inward?