Einstein comes along and says, space and time can warp and curve, that's what gravity is. Now string theory comes along and says, yes, gravity, quantum mechanics, electromagnetism - all together in one package, but only if the universe has more dimensions than the ones that we see.

I can't stand clutter. I can't stand piles of stuff. And whenever I see it, I basically just throw the stuff away.

I can assure you that no string theorist would be interested in working on string theory if it were somehow permanently beyond testability. That would no longer be doing science.

Science is a way of life. Science is a perspective. Science is the process that takes us from confusion to understanding in a manner that's precise, predictive and reliable - a transformation, for those lucky enough to experience it, that is empowering and emotional.

You should never be surprised by or feel the need to explain why any physical system is in a high entropy state.

The number of e-mails and letters that I get from choreographers, from sculptors, from composers who are being inspired by science is huge.

I was holding [my four-year-old daughter] and I said, 'Sophia, I love you more than anything in the universe.' And she turned to me and said, 'Daddy, universe or multiverse?'