JF: Another misunderstanding, which stems from that question, is the idea that the universe was small at the big bang. What was small at the time of the big bang was the entire visible universe, so everything we can see now, which is about 14bn light years away, all of that was compressed to the size of a pinhead. But it was one pinhead in an infinite space, so there's an infinite amount of stuff, as far as we can tell, outside our universe. So it's right to say that it's 14bn years old, but it's wrong to say that it's 14bn light years in size because it's probably infinitely big. However, the question that's probably been asked is what happened before the beginning and the answer to that is that nobody has a clue – so that's the honest answer.