Question

when a block with a hole in it is heated, why does not the material around the hole expand into the hole and make it small?

Answer 1

I cannot remember the proper way to get the result, but I can tell you that the material doesn't grow which will make the hole smaller. Instead, the dimensions stretch, making the hole larger.

Answer 2

So, @Festinger , if that picture is an overgeneralized and simplified molecular structure (molecules and bonds), is the reason why the hole expands that all those bond lengths increase? Most notably for this problem, the ones around the hole?

I don't understand it, but I'd like too. And the structure would have many more molecules than that, so I'm imagining possible deformations that would not be noticeable on a macroscopic level.