My emotional investment is in finding truth. If string theory is wrong, I'd like to have known that yesterday. But if we can show it today or tomorrow, fantastic.

There's a picture of my dorm room in the college yearbook as the most messy, most disgusting room on the Harvard campus, where I was an undergraduate.

String theory envisions a multiverse in which our universe is one slice of bread in a big cosmic loaf. The other slices would be displaced from ours in some extra dimension of space.

The pinpoints of starlight we see with the naked eye are photons that have been streaming toward us for a few years or a few thousand.

Free will is the sensation of making a choice. The sensation is real, but the choice seems illusory. Laws of physics determine the future.

Over the centuries, monumental upheavals in science have emerged time and again from following the leads set out by mathematics.

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.