I was thinking about Dr. Julius Sumner Miller (a science popularizer of the 50s & 60s) and remembered that, the last time I saw him on TV, he posed a question, but didn’t give the answer. I’m still wondering what the answer might be.
He showed a bit of sheet metal about 6 in. x 6 in. A small hole (about 1/4 in. in diameter) is drilled in it. His question was: If you heat the sheet of metal, the metal will expand. Will the hole become smaller, larger, or stay the same size?