Thanks for the answer, John. Really. It's kinda light-hearted musing on my part. The question came up about the notion of a steel donut being heated and whether the hole would get bigger or smaller.
I immediately thought bigger. I thought about the idea of heating a stubborn nut off of a bolt. I thought of running warm water over a stubborn lid.
But when asked why the expansion of the steel wouldn't expand into the hole, all I could come up with was a bit of conjecture on my part...
...that it is the bond, not the atom that causes expansion. Thus, if the atoms that make up the innermost ring of atoms (the one that would define the perimeter of the center hole), the atoms are not going to change, but they will exhibit the same force of expansion in the bonds between them.
In fact, if there were only one ring of atoms, I doubt that anyone would even wonder if the ring would get bigger. It would seem more obvious.
And the atoms can't "leapfrog" one another. We're not talking about melting the steel. We've all seen sugar cookies close up holes as they expand in the heat of the oven.
I further figured that, at the very least, there would be a "keystone-ing" effect -- in other words, the center ring of atoms, rather than getting compressed by the action of the outer atoms "trying" to expand in all directions, would instead, be more inclined to direct all expansion outward. The "keystone-ing" by those atoms would, in effect, be the same as if the two bars in the first scenario met in the middle and thus started pushing all expansion toward the opposite ends.
I'm sure there's a simpler explanation. That was just what my sense of things came up with.
Sadly, Zogg drop things on foot all time. And to frustrate Zogg even more, bad words not invented yet.