When I wrestled, I would set aside the time to wrestle, so that in my mind it didn't interfere with my study time. If I'd say, "I'm going to study this many hours, then I'm going to go work out and wrestle," then when that time comes, you don't feel like you should be doing something else. That helped me psychologically. But otherwise? When I'm wrestling, I'm not studying the universe. And when I'm studying the universe, I'm not wrestling.

Essentially every scientist, when posed with the question, "If you want to get science knowledge from Mars, do you want to send a geologist or do you want to send a robot?" Well, the real answer is, you can send 100 robots for the price of sending one geologist, so let's send 100 robots to 100 different locations, and then we would all benefit. So that's the answer you would get. And I agree with that answer.

Ignorance is a virus. Once it starts spreading it can only be cured by reason. For the sake of humanity, we must be that cure.

Astronauts are the only kind of celebrity I know who can have a line of people waiting for their autograph, even if the line of people does not know in advance the astronaut's name.

Everything we do understand about the universe - the periodic table of elements, Einstein's laws, Newton's laws, all of chemistry, all of biology - that's 4 percent of the universe. We got to the moon on the 4 percent we do understand. We landed on Mars on the 4 percent we do understand. So the day we crack the nut of the rest of that 95 percent... Oh my gosh.

Part of knowing how to think is knowing how the laws of nature shape the world around us. Without that knowledge, without that capacity to think, you can easily become a victim of people who seek to take advantage of you.

Pop culture is the scaffold we all carry around with us.