The caricature of science is that we hold tight to the theories we have, and shun challenges to them. That's just not true. In fact, we hold our highest rewards for those scientists who can prove others wrong. And by the way, they are famous in their own lifetimes. We don't wait until they're dead.

It's odd that the word 'atheist' even exist. I don't play golf, is there a word for non-golf players ?

The universe has really never made things in ones. The Earth is special and everything else is different? No, we’ve got seven other planets. The sun? No, the sun is one of those dots in the night sky. The Milky Way? No, it’s one of a hundred billion galaxies. And the universe - maybe it’s countless other universes.

There's no denying the public's appetite for cosmic discovery.

You have the illusion of free will, but, in fact, that illusion comes about because you don't know the future. Because you are a prisoner of the present, forever locked in transition, between the past and the future.

We didn't go to the moon to explore or because it was in our DNA or because we're Americans. We went because we were at war and we felt a threat.

As a scientist, I want to go to Mars and back to asteroids and the Moon because I'm a scientist. But I can tell you, I'm not so naive a scientist to think that the nation might not have geopolitical reasons for going into space.