Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

This video explains that heat at negative temperatures flows from the negative object to the normal object. If the temperature of the normal object is absolute hot, what happens with the heat? The heat can't be transferred to the absolute hot object, and it apparently does not flow in the other direction, so what happens to it?

share|improve this question
    
Possible duplicates: physics.stackexchange.com/q/62532/2451, physics.stackexchange.com/q/21851/2451 and links therein. –  Qmechanic May 3 '13 at 0:37
    
Neither of those address absolute hot (planck temperature.) –  Waffle May 3 '13 at 0:41
    
It's not clear that absolute hot actually exists. It seems likely that at some energy level a particle could shed energy through pair production. –  Brandon Enright May 3 '13 at 0:46

1 Answer 1

"Absolute Hot" is a cute phrase, but meaningful only in a limited context, where the concept of negative temperature applies. That is, there's a finite number of energy levels in a finite energy range, and whatever particles/quanta/excitations we're studying stay in that context. For example we may be interested in spins of nuclei in a crystal, and how they are affected by magnetic fields.

If a system is at "absolute hot" and you add a bit more energy, the system will be excited in some way making use of energy levels outside (not necessarily above, but probably) the finite range, breaking some contraints (or assumptions) about the system under study. For the nuclear spins example, maybe some atoms become dislodged from the lattics, or the electrons take up the energy in all the marvelous ways described in condensed matter physics. Electrons have no upper limit - they can always escape from the crystal with arbitrarily great escape velocities.

In other words: something will break, changing the system from what it was during discussion of negative temperatures, to something more general. Energy will find a way in, if you force it.

At best, added quanta of energy, such as photons or phonons, will bounce off (a pure white object) or pass through (transparency).

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.