Look up at night. Billions and billions of stars out there, and yet the sky is black? Wait, what? Shouldn't it be glowing like a giant lamp? This is not a silly question, by the way. It's a real puzzle that confused scientists for hundreds of years, and it even has a name: Olbers' paradox. The Forest Problem Imagine you're standing in the middle of a forest. If the forest is small, you can see gaps between the trees. But if the forest goes on forever, then wherever you look,