 I have some boiling water in front of me and this piece of paper. And what I'll do is I'll keep this piece of paper on top of this boiling water. And I want you to predict what will happen. Will you see any kind of movement in the paper? Think about it. Alright, let's see. Well, we do see the paper moving up and down, right? Alright, so now the question is, why is the paper really moving?