[Eelongate]

He meant to write cooling; the moderate (warmer) parts leave, leaving the fanatical 'cold' members. I agree that 'fanatical=cold/moderate=warm' seems a little backwards, but it's that way and not the other because it's an analogy to a real physical process, while evaporative warming doesn't exist.

From 2007: https://www.lesswrong.com/posts/ZQG9cwKbct2LtmL3p/evaporativ...

https://en.wikipedia.org/wiki/Evaporative_cooling_(atomic_ph...

[MontagFTB]

Distillation may be a more appropriate analogy. The unwanted part evaporates away, leaving the more concentrated solution behind.

[DarylZero]

In distillation, the whole input liquid is evaporated by heating, then condensed by cooling and collected.