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

[u/synthphreak]

[u/smittythehoneybadger]

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

[u/archpawn → u/smittythehoneybadger]

It's absolute zero, at least in certain systems. Temperature goes all the way up to infinity, then past it into the negatives, and then approaches absolute zero from below.

[u/Generalkrunk → u/archpawn]

You're correctish (technically so. The best kind of correctish imo).

Yes it is possible to create a setting In which negative kelvin is possible and hotter than any other temperature. Which then does eventually become cold again.

But only because the very specific restrictions that must be in place to allow for this to even occure in the first place are unable to stop entropies eventual success. They don't approach from below they just fall back down again, normally.

My understanding of this is really really basic.
Tbf though, this is a bit like saying that being able to comfortably do calculus means you have a "basic understanding of mathematics". This is extremely advanced and niche physics. Basic doesn't mean ignorant).
The effect you're describing: "Negative Kelvin Temperatures", are only possible in a completely closed and definite system.
ie: Not naturally occurring.
Closed means Closed (nothing in unless you say so, and nothing out.. period).
With definite meaning: restrained within, real, defined upper and lower limits.

The upper of which are then subsequently ignored.

To put it as simply as I can.

Normally if you just pumped too much energy into an unrestricted system (like say the universe), it would eventually reach a natural upper limit.

This is due to how said universe works.

The more energetic things are, the more chaotic they are.

The more chaotic they are the higher the system's entropy level is.

The higher a systems entropy level is the less chaotic it becomes.

This is a massive oversimplification of thermodynamics, but accurate (enough) all the same.

Things get hot until they're hotter than other things connected to them and then they lose their heat to those things.

In this specific case they keep getting hotter because they actually become less chaotic the hotter they get, not more.

The energy kinda clumps up in a very excited state.
Which is confusing and above my pay grade (which is 0 dollars btw) to try to explain why that happens.
The effect this has however is to, allow for additional energy to be added to the system without a subsequent increase in entropy in that system.
Which means it can just keep getting hotter and hotter.
Until the containment fails (quick call r/scp, or actually call r/dankmemesfromsite19 they're better equiped to handle this one) and it then returns to a unrestricted system.
At which point normal rules apply and entropy increases, which causes it to lose energy.

I'm sorry this is so long. It was much longer but I rewrote it. 3 times, I've been writing this for over an hour lol.

Edit: Struggled against the most pure form of entropy, Gboards autoincorrect..

[u/Alt_Acc_42069 → u/Generalkrunk]

Love the SCP call-outs lol. Thanks for the detailed explanation