There may be many Big Bangs that happened at various and far-flung locations, each creating its own swelling, spatial expanse, each creating a universe - our universe being the result of only one of those Big Bangs.

Physics grapples with the largest questions the universe presents. Where did the totality of reality come from? Did time have a beginning?

General relativity is in the old Newtonian framework where you predict what will happen, not the probability of what will happen. And putting together the probabilities of quantum mechanics with the certainty of general relativity, that's been the big challenge and that's why we have been excited about string theory, as it's one of the only approaches that can put it together.

We can certainly go further than cats, but why should it be that our brains are somehow so suited to the universe that our brains will be able to understand the deepest workings?

Every moment is as real as every other. Every 'now,' when you say, 'This is the real moment,' is as real as every other 'now' - and therefore all the moments are just out there. Just as every location in space is out there, I think every moment in time is out there, too.

For me it's been very exciting to contribute to the public's understanding of how rich and wondrous science is.

I may be a Jewish scientist, but I would be tickled silly if one day I were reincarnated as a Baptist preacher.