When World War II came along, which was when I was a teenager, we all expected we would have anthrax bombs and this kind of stuff. We thought it would be a biological war. Fortunately it wasn't and, but it's because the danger is still there and by some miracle we escaped all that, so you never can tell what it going to happen, but biology certainly could be even worse than physics and chemistry.

That's what I learned from World War II. Things are always more complicated than most people believe.

Computer models of the climate....[are] a very dubious business if you don't have good inputs.

I think that the artificial-intelligence people are making a lot of noise recently, claiming that artificial intelligence is making huge progress and we're going to be outstripped by the machines. But, in my view, this whole field is based on a misconception. I think the brain is analog, whereas the machines are digital. They really are different. So I think that what the machines can do, of course, is wonderful, but it's not the same as what the brain can do.

The Ph.D. system was designed for a job in academics. And it works really well if you really want to be an academic, and the system actually works quite well. So for people who have the gift and like to go spend their lives as scholars, it's fine. But the trouble is that it's become a kind of a meal ticket - you can't get a job if you don't have a Ph.D.

There are two different ways of looking at the universe; and it's the same universe with two different windows. The science window gives you a view of the world, and the religion window gives you a totally different view. You can't look at both of them at the same time, but they're both true.

You ask: what is the meaning or purpose of life? I can only answer with another question: do you think we are wise enough to read God's mind?