Our best shot at finding life in our solar system might be to look at the moons of Jupiter and Saturn. Mars, increasingly, looks like a dead planet. But the oceans beneath the ice cover of the moons of Jupiter and Saturn may actually have more liquid water than the oceans of Earth.

We physicists don't like to admit it, but some of us are closet science fiction fans. We hate to admit it because it sounds undignified. But when we were children, that's when we got interested in science, for a lot of us.

The brain weighs only three pounds, yet it is the most complex object in the solar system.

I had two passions when I was a child. First was to learn about Einstein's theory and help to complete his dream of a unified theory of everything. That's my day job. I work in something called string theory. I'm one of the founders of the subject. We hope to complete Einstein's dream of a theory of everything.

I believe we exist in a multiverse of universes.

You can mass-produce hardware; you cannot mass-produce software - you cannot mass-produce the human mind.

Beyond work and love, I would add two other ingredients that give meaning to life. First, to fulfill whatever talents we are born with. However blessed we are by fate with different abilities and strengths, we should try to develop them to the fullest, rather than allow them to atrophy and decay. ... Second, we should try to leave the world a better place than when we entered it.