If you start out with a tragic view of life, then anything since is just a bonus.

The biggest breakthrough in the next 50 years will be the discovery of extraterrestrial life. We have been searching for it for 50 years and found nothing. That proves life is rarer than we hoped, but does not prove that the universe is lifeless. We are only now developing the tools to make our searches efficient and far-reaching, as optical and radio detection and data processing move forward.

The thing that makes me most optimistic is China and India - both of them doing well. It's amazing how much progress there's been in China, and also India. Those are the places that really matter - they're half of the world's population. They're the places where things are enormously better now than they were 50 years ago. And I don't see anything that's going to stop that.

Some of my friends like to keep science and religion together, but I certainly like to keep them separate.

You have this world of mathematics, which is very real and which contains all kinds of wonderful stuff. And then we also have the world of nature, which is real, too.

As far as I can see, our concentration of different abilities in one species - there's nothing I can see that in this Darwinian evolution that could've done that. So it seems to be a miracle of some sort.

So long as you have courage and a sense of humor, it is never too late to start life afresh.