If you get asteroids about a kilometer in size, those are large enough and carry enough energy into our system to disrupt transportation, communication, the food chains, and that can be a really bad day on Earth.

When NASA dreams big America dreams big. People...kids say, 'I want to do that when I grow up'. Because you want to do what's visible to you.

No matter what eyewitness testimony is in the court of law, it is the lowest form of evidence in the court of science.

Don't get in the way of children who find it natural and obvious to explore the world around them - even if it means they make a mess of your kitchen or living room. It's all about your perspective on these things. Let them play. When you do, the kids do not have to be reintroduced to ways of questioning nature, and the task of promoting science would be a trivial exercise.

One should not be too distracted by definitions. Ideas transcend definitions.

Some morning while your eating breakfast and you need something new to think about, though, you might want to ponder the fact that you see your kids across the table not as they are but as they once were, about three nanoseconds ago.

Part of me thinks that I've been called by the universe, to get all sort of spiritual about it. Like, I've had no actual say in the matter. The universe found me.