“The atoms like each other to different degrees. Oxygen, for instance in the air, would like to be next to carbon, and if they get near to each other, they snap together. If they’re not too close though, they repel and they go apart, so they don’t know that they could snap together.
It’s just as if you had a ball, it was trying to climb a hill and there was a hole it could go into, like a volcano hole, a deep one. It’s rolling along, it doesn’t go down in the deep hole, because if it starts to climb the hill and then rolls away again. But if you made it go fast enough, it will fall into the hole.
And so, if you set something like wood and oxygen, there’s carbon in the wood from the tree, and the oxygen comes and hits it, the carbon, but not hard enough, it just goes away again, the air is always coming, nothing is happening. If you can get it faster, by heating it up somehow, somewhere, or somehow, get it started, a few of them come fast, they go over the top so to speak, they come close enough to the carbon and snap in, and that gives a lot of jiggly motion, which might hit some other atoms, making those go faster, so they can climb up and bump against other carbon atoms, and they jiggle and they make them others jiggle, and you get a terrible catastrophe, which is one after the other all these things are going faster and faster and snapping in and the whole thing is changing.
That catastrophe is a fire.”