We are entering an increasingly dangerous period of our history. But I'm an optimist.

While physics and mathematics may tell us how the universe began, they are not much use in predicting human behavior because there are far too many equations to solve. I'm no better than anyone else at understanding what makes people tick, particularly women.

I thought Eddie Redmayne portrayed me very well... At times I thought he was me.

Mankind's greatest achievements have come about by talking and its greatest failures by not talking. It doesn’t have to be like this.

I've noticed that even people who believe in fate look both ways before crossing the street.

Some individuals are better able than others to draw the right conclusions about the world about them and act accordingly. These individuals will be more likely to survive and reproduce so their pattern of behaviour and thought will become dominant

If human life were long enough to find the ultimate theory, everything would have been solved by previous generations. Nothing would be left to be discovered.