I couldn't claim that I was smarter than sixty-five other guys--but the average of sixty-five other guys, certainly!

We need to teach how doubt is not to be feared but welcomed. It's OK to say, "I don't know."

The whole question of imagination in science is often misunderstood by people in other disciplines. ... They overlook the fact that whatever we are allowed to imagine in science must be consistent with everything else we know.

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.

I'm going to play with physics, whenever I want to, without worrying about any importance whatsoever.

We absolutely must leave room for doubt or there is no progress and there is no learning. There is no learning without having to pose a question. And a question requires doubt. People search for certainty. But there is no certainty. People are terrified — how can you live and not know? It is not odd at all. You only think you know, as a matter of fact. And most of your actions are based on incomplete knowledge and you really don’t know what it is all about, or what the purpose of the world is, or know a great deal of other things. It is possible to live and not know.