how do we cool things down?

Question

I understand how we heat them, by putting energy into the system. but how do we use the energy to cool them down?

In: 5

Answer 1

We cool things down by “moving” the heat somewhere else. That process of moving the heat creates heat by itself (no thermal cycle is 100% efficient, or more efficient than the ideal Carnot cycle) so that adds heat to the removed heat. We make more heat than the one we “removed”.

Nothing in Universe “cools down” by itself. The third law of thermodynamics says that system entropy always increases. Some say that is the only law that points to the existence of an “arrow of time”, how time flows only in one direction.