There’s so much distance between the fundamental rules and the final phenomenon, that it’s almost unbelievable that the final variety of phenomenon can come from such a steady operation of such simple rules.

If we want to solve a problem that we have never solved before, we must leave the door to the unknown ajar.

Words can be meaningless. If they are used in such a way that no sharp conclusions can be drawn.

Mathematics is not just a language. Mathematics is a language plus reasoning.

I have argued flying saucers with lots of people. I was interested in possible. They do not appreciate that the problem is not to demonstrate whether it's possible or not but whether it's going on or not.

There are thousands of years in the past, and there is an unknown amount of time in the future. There are all kinds of opportunities, and there are all kinds of dangers.

Physics is like sex: sure, it may give some practical results, but that's not why we do it.