No, James Clerk Maxwell, probably the third or fourth greatest physicist in history. He’s most famous for completing the classical understanding of electromagnetism, but he also did a lot of important work in thermodynamics.
In all seriousness, all a thermos does is it keeps what’s inside of it from exchanging heat with its environment, and thereby in practice keeps the contents at the same temperature they were at when they were put in. If you boil lemonade and put it in one thermos, and freeze coffee and put it in another, the lemonade will stay hot and the coffee will stay cold, even though they’re “supposed” to be the other way around.
Put it another way: A wall can either keep people inside, or keep them outside. How does it know which to do? It doesn’t; it just keeps people on the same side they start on. A thermos is like a wall, but one that blocks heat, not people.
They don’t know. A thermos is pretty stupid so you have to tell it what to do with the contents, like, “keep this soup hot thermos.” I take advantage of this by filling mine with water and telling it, “keep this Czech style wheat beer ice cold thermos.” Delicious.
Yeah, one time I totally screwed up and forgot to tell my Thermos to activate hot mode, so when I went to drink my hot chocolate, I ended up with cold chocolate! It ruined my day.