[davidinosauro]

You might want to read about Maxwell's daemon [1]. I came across this a few weeks back, two links away from the HN homepage.

I found it intreaguing and read more about it but I can't quite umderstand the proposed solutions, likely due to my lack of background in thermodynamics.

[1] https://en.m.wikipedia.org/wiki/Maxwell's_demon

[blueblisters]

Clearly, Maxwell was much better (and funnier) in articulating what I was asking. Looks Maxwell's demon can work some of the time at a molecular level, but on average, you need to do work to extract useful heat from matter at a macroscopic level. The hypothesis being that you need to do work just to identify hot/energetic molecules from the cold/low-energy molecules.