I don't think the human race will survive the next thousand years, unless we spread into space.

We only have to look at ourselves to see how intelligent life might develop into something we wouldn't want to meet.

[On President Bush's plan to get to Mars in 10 years] Stupid. Robots would do a better job and be much cheaper because you don't have to bring them back.

I don't believe that the ultimate theory will come by steady work along existing lines. We need something new. We can't predict what that will be or when we will find it because if we knew that, we would have found it already!

Time travel used to be thought of as just science fiction, but Einstein's general theory of relativity allows for the possibility that we could warp space-time so much that you could go off in a rocket and return before you set out.

Science does not deny religion, it just offers a simpler alternative.

Nothing is better than reading and gaining more and more knowledge.