The average student emerges at the end of the Ph.D. program, already middle-aged, overspecialized, poorly prepared for the world outside, and almost unemployable except in a narrow area of specialization. Large numbers of students for whom the program is inappropriate are trapped in it, because the Ph.D. has become a union card required for entry into the scientific job market.

I think it's a big mistake to decide too soon what you're going to do with your life.

There is nothing so big nor so crazy that one out of a million technological societies may not feel itself driven to do, provided it is physically possible.

Do not imagine that you have to know everything before you can do anything. My own best work was done when I was most ignorant.

I think it's much better to have your eyes open, but on the other hand, of course it can do harm if you tell people look, there's all these terrible things you can do and then some idiot may go ahead and do it.

Science and religion are, of course, two different ways of looking at the universe; and it's the same universe with two different windows.

That's the beautiful thing about science - that it's all about things we don't understand, not just the things we do understand.