What We Cannot Know: Explorations at the Edge of Knowledge

by Marcus du Sautoy

Looking back at the Edges I’ve visited so far, nothing seems quite as unanswerable as the question of whether the universe is infinite. Chaos theory told me that the future is unknowable, but I can just wait until it becomes the present and then I’ll know. As I slice my dice, I might actually hit a point at which space is quantized, so it’s possible that there are only finitely many steps inside my dice before I hit the indivisible. It’s true that it might be almost impossible to navigate this descending staircase, but it isn’t a challenge that is a priori unsolvable. And Heisenberg’s uncertainty principle does not so much challenge us to give an answer but rather to consider whether the questions we are asking are well posed. It’s not that we can’t know position and momentum simultaneously; the revelation is that it is not a question that it makes sense to ask.