Pretending to know everything closes the door to finding out what's really there.

I lose sleep at night wondering whether we are intelligent enough to figure out the universe. I don't know.

As a child, I was aware that, at night, infrared vision would reveal monsters hiding in the bedroom closet only if they were warm-blooded. But everybody knows that your average bedroom monster is reptilian and cold-blooded.

Politics will take whatever shape it needs for people to get elected. But at the end of the day, the population remains and that's really, as an educator, who I care about.

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?

The universe's destiny has very little to do with the near-term destiny of Earth.

There are as many atoms in each molecule of your DNA as there are stars in the typical galaxy. This is true for dogs, and bears, and every living thing. We are, each of us, a little universe.