Lots of people think, well, we're humans; we're the most intelligent and accomplished species; we're in charge. Bacteria may have a different outlook: more bacteria live and work in one linear centimeter of your lower colon than all the humans who have ever lived. That's what's going on in your digestive tract right now. Are we in charge, or are we simply hosts for bacteria? It all depends on your outlook.

When you advance a frontier and you do tomorrow what's never been done today, you have to innovate to make that happen. You become an innovation culture. When I grew up, every time I turned around it was, "Oh, here's the longest bridge or the deepest tunnel or the fastest airplane." And I originally thought that was just kind of like a pissing contest with men with too much testosterone. And then I realized that to make the tallest building you have to innovate. To make the fastest train you have to design the train in a way that it's never been designed before.

In any city with lots of skyscrapers, lots of skyline, the moon seems bigger than it is. It's called the moon illusion.

I object to religion in science classrooms not because it's religion but because it's not science.

I agree that we should go back to the moon and on to Mars. We should treat all objects in the solar system, including comets and asteroids, as exploration targets.

Intelligent design is a philosophy of ignorance.

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.