A watch worn by a particle of light would not tick at all. Light realizes the dreams of Ponce de Leon and the cosmetics industry: it doesn't age.

I have long thought that anyone who does not regularly - or ever - gaze up and see the wonder and glory of a dark night sky filled with countless stars loses a sense of their fundamental connectedness to the universe.

In essence, we string theorists have been trying to work out the score of the universe, the harmonies of the universe, the mathematical vibrations that the strings would play. So musical metaphors have been with us in science since the beginning.

When you drive your car, E = mc2 is at work. As the engine burns gasoline to produce energy in the form of motion, it does so by converting some of the gasoline's mass into energy, in accord with Einstein's formula.

Most people don’t question the practice of eating meat. Many of these people care about animals and the environment, some deeply. But for some reason-force of habit, cultural norms, resistance to change-there is a fundamental disconnect whereby these feelings don’t translate into changes of behavior.

Art makes us human, music makes us human, and I deeply feel that science makes us human.

We're on this planet for the briefest of moments in cosmic terms, and I want to spend that time thinking about what I consider the deepest questions.