I mean science was blamed for all the horrors of World War I, just as it's blamed today for nuclear weapons and quite rightly.

If the tools are bad, nature's voice is muffled. If the tools are good, nature will give us a clear answer to a clear question.

[On Richard P. Feynman's live demonstration of the rigidity of the O-rings when cold that doomed the space shuttle Challenger, killing seven astronauts:] The public saw with their own eyes how science is done, how a great scientist thinks with his hands, how nature gives a clear answer when a scientist asks her a clear question.

In the end it is how you fight, as much as why you fight, that makes your cause good or bad.

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.

Science and religion are two windows that people look through, trying to understand the big universe outside, trying to understand why we are here. The two windows give different views, but they look out at the same universe. Both views are one-sided, neither is complete. Both leave out essential features of the real world. And both are worthy of respect.

Science is not a collection of truths. It is a continuing exploration of mysteries.