>>11362928Nope, negative absolute temperature is a thing
>>11362710Negative absolute temperature states are defined by the role of temperature in the Boltzmann distribution. Basically, at any positive temperature, particles are more likely to occupy lower energy states than higher energy ones. This will always be the case as long as the system is at thermal equilibrium, and there is no upper limit on the energy states. However, it is possible to engineer microscopic systems where there is an upper limit on the energy states, in which case you can have an equilibrium where the particles are more likely to occupy higher energy states than lower ones.
This has been achieved experimentally:
https://arxiv.org/abs/1211.0545You may question the validity of whether this is "truly" a negative absolute temperature. It really is in the sense that, if you were to quickly put this system in thermal contact with an arbitrarily hot, positive temperature body, heat would momentarily flow from the negative temperature body to the hot body, no matter HOW high the positive temperature of the hot body is. This again has to do with the Boltzmann distribution and statistical mechanics.
