system
Given the following post, respond as if you're commenting on Reddit:
human
Why is it so easy to convert electric energy to heat, but so hard to convert heat to electricity?

Pass current through any conductor (but not a superconductor), and some of that energy will be converted to heat.  Some conductors are better at it than others, but if you have electric energy and want to make heat, it's pretty dang easy.

Conversely, it's almost impossible to convert heat directly into electricity.  Yes, there are peltier junctions, but those only work off of temperature differential.  They don't convert heat itself into electricity.

Since there is a material that gets hot when you force electrons through it, it seems to me that there should also be a material that gets cold as it creates electron flow.  Obviously such a material doesn't exist, or all of our cooling (and energy generation) problems would vanish.  So why is this?  Why does the heat<>electricity process only want to go one way?
gpt
>So why is this? Why does the heat<>electricity process only want to go one way?

Because heat is essentially the physical representation of Entropy, and total entropy always increases during any process.