The electron is a theory. But the theory is so good we can almost consider them real.

Physicists like to think that all you have to do is say, these are the conditions, now what happens next?

When you're thinking about something that you don't understand, you have a terrible, uncomfortable feeling called confusion... Now, is the confusion's because we're all some kind of apes that are kind of stupid working against this, trying to figure out [how] to put the two sticks together to reach the banana and we can't quite make it... So I always feel stupid. Once in a while, though, the sticks go together on me and I reach the banana.

Of course, you only live one life, and you make all your mistakes, and learn what not to do, and that's the end of you.

Turbulence is the most important unsolved problem of classical physics.

... it is impossible to explain honestly the beauties of the laws of nature in a way that people can feel, without their having some deep understanding of mathematics. I am sorry, but this seems to be the case.

There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe there ever was such a time ... On the other hand, I think I can safely say that nobody understands quantum mechanics.