Question: how many dimensions do you think the universe has?

Evan Keane answered on 24 Jun 2011:

Well the universe definitely has at least 4 dimensions! There are some theories in physics, like string theory, which can only work if there are “extra dimensions” (although you can have extra dimensions without string theory being true). String theory requires that there are 11 dimensions, the other dimensions (which we’ve not seen) are thought to be “compact”, i.e. very very small. There is as yet no evidence to prove that string theory is correct, but lots of people are working on it, and thinking up tests we can do to see if it is right. 😀