Anyone who has wrestled knows that it's the hardest thing in the world to do. Anyone who says something else is the hardest thing has never wrestled. That's what I have found. ... You don't wrestle because it's easy, you wrestle because it's hard. I don't do astrophysics because it's easy, I do it because it's hard. And I juxtapose the two in my mind, body, and soul all the time.

When you innovate, the jobs can't go overseas because other countries haven't figured out how to do it yet.

Why can't Pluto be a planet? Some people like Pluto. And if it doesn't exist then they don't have a favorite planet. Right? Please write back but not in cursive because I can't read cursive.

One of the greatest features of science is that it doesn't matter where you were born, and it doesn't matter what the belief systems of your parents might have been: If you perform the same experiment that someone else did, at a different time and place, you'll get the same result.

The typical person has no trouble believing without knowing. What people need to realize is simply that you do not need to believe to know.

You can make a stack high enough to reach the moon and back, and only then will you have used your 100 billion hamburgers. This is terrifying news to cows.

On Venus you could cook a 16-inch pepperoni pizza in seven seconds, just by holding it out to the air. (Yes, I did the math.)