Last I checked, Bill Gates was worth $50 billion. If the average employed adult, who is walking in a hurry, will pick up a quarter from the sidewalk, but not a dime, then the corresponding amount of money given their relative wealth that Bill Gates would ignore if he saw it lying on the street is $25,000.

Chimpanzees are an evolutionary hair's-width from us.... Now imagine a species on Earth, or anywhere else, as smart compared with humans as humans are compared with chimpanzees. How much of the universe might they figure out?

For me, the most fascinating interface is Twitter. I have odd cosmic thoughts every day and I realized I could hold them to myself or share them with people who might be interested.

The theory of evolution, like the theory of gravity, is a scientific fact.

The universe has really never made things in ones. The Earth is special and everything else is different? No, we’ve got seven other planets. The sun? No, the sun is one of those dots in the night sky. The Milky Way? No, it’s one of a hundred billion galaxies. And the universe - maybe it’s countless other universes.

A conspiracy theorist is a person who tacitly admits that they have insufficient data to prove their points. A conspiracy is a battle cry of a person with insufficient data.

I'm often asked whether I believe in Global Warming. I now just reply with the question: "Do you believe in Gravity?"