Science is the engine of prosperity. All the prosperity we see around us is a byproduct of scientific inventions. And that's not being made clear to young people. If we can't make it clear to young people they're not going to go into science. And science will suffer in the United States.

It's pointless to have a nice clean desk, because it means you're not doing anything.

We're headed for what is called Type 1 Civilization, planetary civilization. Type 2 would be stellar civilization, like Star Trek. Type 3 Civilization would be galactic, like Star Wars. We are Type 0. We get our energy from dead plants, oil and coal. But the question is: Will we make it? Will we make the transition from Type 0 to Type 1? It's not clear.

A soul might very well exist, but we, as physicists, try to measure and quantify everything. So far, no one has been able to create an experiment to do this for the soul. Efforts have been made to weigh the body after death, but each time we find no evidence of a soul. So a soul may very well exist, but it is not a testable theory.

Robots may gradually attain a degree of 'self-awareness' and consciousness of their own.

One day when I was 8 years old, everyone was talking in hushed tones about a great scientist that had just died. His name was Albert Einstein.

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.