system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5; Negative Absolute Temperature

I understand the whole negative absolute temperature is not colder than zero Kelvin but actually hotter.. But I don't understand how this occurs or what kind of things might be possible due to this idea.
gpt
This phenomenon uses a different definition of temperature than we're used to. Negative temperatures only apply in quantum situations, not everyday classical ones.

Temperature, in this case, describes what happens when you add energy to a system. Usually, when you add energy to something, it gets more disorganized - entropy increases. This is positive temperature. But in a quantum system that has "maxed out" its entropy, or in other words is "maximum hot", adding energy can only decrease its entropy. This is negative temperature. If a negative temperature system touched a positive temperature one, energy would flow from the negative to positive.