Dark matter and dark energy are two things we measure in the universe that are making things happen, and we have no idea what the cause is.

Curiosity is unknown. All adults were once kids and once curious, but as adults you don't remember that and you see curiosity when it's expressed in children as a pathway to household disaster. They're simply exploring their environment, manifesting their curiosity. So what you need to do is create an environment where curiosity is rewarded rather than punished, or thwarted.

Somehow it's O.K. for people to chuckle about not being good at math. Yet if I said, 'I never learned to read,' they'd say I was an illiterate dolt.

In America, there are people who don't read science fiction but still think about tomorrow, so it's not only the force of science-fiction that makes you a tomorrow thinker.

We already know the limits of Einstein's theories. From the centers of black holes at the very beginning of the universe - we call these singularities - Einstein's equations fail. In fact, people have joked that's where God is dividing by zero.

The persistent failures of controlled, double-blind experiments to support the claims of parapsychology suggest that what's going on is nonsense rather than sixth sense.

I'd like - inviting aliens and have them observe what we do because so much of what we do that we take for granted will just be weird or extraordinary or just plain dumb when observed by an alien from another civilization.