In some sense, gravity does not exist; what moves the planets and the stars is the distortion of space and time.

No one knows who wrote the laws of physics or where they come from. Science is based on testable, reproducible evidence, and so far we cannot test the universe before the Big Bang.

I vowed to myself that when I grew up and became a theoretical physicist, in addition to doing research, I would write books that I would have liked to have read as a child. So whenever I write, I imagine myself, as a youth, reading my books, being thrilled by the incredible advances being made in physics and science.

The reactors in Japan are stable in the same way that a ticking time bomb is also stable. It wouldn't take much to light the fuse - a 6.6 earthquake, like what happened today in Japan, a pipe break, an over-pressurized containment vessel - anything could set it off, in which case we would have another Chernobyl, three times the magnitude of a Chernobyl accident.

The river of time may fork into rivers, in which case you have a parallel reality and so then you can become a time traveler and not have to worry about causing a time paradox.

I have nothing against investment banking, but it's like massaging money rather than creating money.

The next big accelerator might be the ILC in Japan, a linear collider which might be able to probe the boundaries of string theory. So we physicists have to learn how to engage the public so that taxpayers money is used to explore the nature of the universe.