Who you are, where you've been and what you've done is all up here, captured and preserved in your memories. If you lost that - the story of your own origins - you'd lose your identity, your sense of self.

I'm a fan of the planets in any combination. When I was born, Mercury, Venus, Jupiter, Saturn, Uranus, Neptune, Pluto, the Sun, and the Moon were all in the sky.

So what is true for life itself is no less true for the universe: knowing where you came from is no less important than knowing where you are going.

Creativity is seeing what everyone else sees, but then thinking a new thought that has never been thought before and expressing it somehow. It could be with art, a sculpture, music or even in science. The difference, however, between scientific creativity and any other kind of creativity, is that no matter how long you wait, no one else will ever compose "Beethoven's Ninth Symphony" except for Beethoven. No matter what you do, no one else will paint Van Gogh's "Starry Night." Only Van Gogh could do that because it came from his creativity.

We already know the limits of Einstein's theories. From the centers of black holes at the very beginning of the universe - we call these singularities - Einstein's equations fail. In fact, people have joked that's where God is dividing by zero.

There are street artists. Street musicians. Street actors. But there are no street physicists. A little known secret is that a physicist is one of the most employable people in the marketplace - a physicist is a trained problem solver.

I don't ever tell people what to do! Even if it seems and feels that way sometimes, I don't think I should tell a person how to spend their money. I try not to tell people what to read.