The revolutionary breakthrough will come with rockets that are fully and rapidly reusable. We will never conquer Mars unless we do that. It'll be too expensive. The American colonies would never have been pioneered if the ships that crossed the ocean hadn't been reusable.

I think life on Earth must be about more than just solving problems... It's got to be something inspiring, even if it is vicarious.

With artificial intelligence, we are summoning the demon. In all those stories where there's the guy with the pentagram and the holy water, it's like, yeah, he's sure he can control the demon. Didn't work out.

As a child I would just question things.

Self-driving cars are the natural extension of active safety and obviously something we should do.

If something's important enough, you should try. Even if you - the probable outcome is failure.

Mars is the only place in the solar system where it's possible for life to become multi-planetarian.