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.

It is characteristic of all deep human problems that they are not to be approached without some humor and some bewilderment.

The biologists have essentially been pushed aside. Al Gore's just an opportunist. The person who is really responsible for this overestimate of global warming is Jim Hansen. He consistently exaggerates all the dangers.

One of the memorable moments of my life was when Willard Libby came to Princeton with a little jar full of crystals of barium xenate. A stable compound, looking like common salt, but much heavier. This was the magic of chemistry, to see xenon trapped into a crystal.

For me, science is just a bunch of tools - it's like playing the violin. I just enjoy calculating, and it's an instrument I know how to play. It's almost an athletic performance, in a way. I was just watching the Olympics, and that's how I feel when proving a theorem.

The essential fact which emerges ... is that the three smallest and most active reservoirs ( of carbon in the global carbon cycle), the atmosphere, the plants and the soil, are all of roughly the same size. This means that large human disturbance of any one of these reservoirs will have large effects on all three. We cannot hope either to understand or to manage the carbon in the atmosphere unless we understand and manage the trees and the soil too.

I think the fact that Aldous Huxley wrote Brave New World and talked about anthrax bombs probably helped because at least we... people had the understanding before the war began that's something we didn't want to get into.