system
Given the following post, respond as if you're commenting on Reddit:
human
Is it possible to produce energy from the differential between ambient temperature and absolute zero?

I understand that constructions such as thermocouples can produce electricity as a result of a temperature gradient.  What I am curious about is whether it is theoretically possible to, for example, have some sort of crystalline structure that naturally converts a large amount of its thermal energy to electrical energy.  Or is this prohibited by physical theory?
gpt
So essentially this theoretical substance would spontaneously get colder on its own, its heat flowing out of it into the ambient?  Nope.  That's not how the universe works.  You have to spend energy to make that happen, it doesn't do it on its own.  Otherwise refrigerators wouldn't need to be plugged in.