Random Ideas #49: Maxwell's Demon is possible · 5:42am Sep 9th, 2017
tldr: Maxwell's Demon is a theoretical door that can make a enclosed system (insulated box, isolated room, etc) colder by letting colder molecules in, and blocking it when it tries to bounce out, and vice versa for hot molecules.
Nothing is this precise IRL.
Maybe magic
No idea what this can be used for. Bullshit tier heat engine?