I think the next [21st] century will be the century of complexity. We have already discovered the basic laws that govern matter and understand all the normal situations. We don't know how the laws fit together, and what happens under extreme conditions. But I expect we will find a complete unified theory sometime this century. The is no limit to the complexity that we can build using those basic laws.

My advice to other disabled people would be, concentrate on things your disability doesn't prevent you doing well, and don't regret the things it interferes with. Don't be disabled in spirit, as well as physically.

I do not believe in a personal God.

Most sets of values would give rise to universes that, although they might be very beautiful, would contain no one able to wonder at that beauty.

Because imaginary time behaves like another direction in space, histories in imaginary time can be closed surfaces, like the surface of the Earth, with no [existential] beginning or end.

If you understand how the universe operates, you control it in a way.

If aliens visit us, the outcome would be much as when Columbus landed in America, which didn't turn out well for the Native Americans.