Sometimes we talked about the nature of the human soul and about the Cosmic Unity of souls that I had believed in so firmly when I was 15 years old. My mother did not like the phrase Cosmic Unity. It was too pretentious. She preferred to call it a world soul.

It's not going to be just humans colonizing space, it's going to be life moving out from the Earth, moving it into its kingdom. And the kingdom of life, of course, is going to be the universe.

If women are doing a Ph.D., they have a conflict between raising a family or finishing the degree, which is just at the worst time - between the ages of 25 to 30 or whatever it is. It ruins the five years of their lives.

It's us that's really amazing.

The purpose of thinking about the future is not to predict it but to raise people's hopes.

As a working hypothesis to explain the riddle of our existence, I propose that our universe is the most interesting of all possible universes, and our fate as human beings is to make it so

I'm happy that I've raised six kids, and not one of them is a Ph.D.