This fear factor, this war driver is a very strong one and it's been with the species ever since the beginning and it motivated the Great Wall of China. War can be aggressive or defensive, right? So it motivated the Great Wall of China. Our space program was reactive to Russia.

I am proud to be part of a species where a subset of its members willingly put their lives at risk to push the boundaries of our existence.

In just one year, the expenditure of of the U.S.'s military budget is equivalent to the entire 50-year running budget of NASA combined.

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?

In modern times, if the sole measure of what’s out there flows from your five senses then a precarious life awaits you.

Something we all have as kids and is beaten out of us as adults. Parents come up to me, "How do I get my kids interested in science?" They're already interested in science. Just stop beating it out of them.

Private enterprise can never lead a space frontier. It's not possible because a space frontier is expensive, it has unknown risks and it has unquantified risks.