Three and a half million years ago our ancestors - yours and mine - left these traces [indicates footprints]. We stood up and parted ways from them. Once we were standing on two feet, our eyes were no longer fixated on the ground. Now, we were free to look up and wonder.

People think about life from day-to-day rather than thinking about life as something that invents a new kind of tomorrow.

No one is dumb who is curious.

We should not measure our space-faring era by where footprints have been laid.... We should measure our era by how many people take no notice at all. A legacy rises to become culture only when its elements are so common that they no longer attract comment.

If Mars formed life, then life on Earth could have been seeded by life on Mars, making every life form on Earth descended from Martians.

Dark matter and dark energy are two things we measure in the universe that are making things happen, and we have no idea what the cause is.

I never got into 'Star Wars.' Maybe because they made no attempt to portray real physics. At all.