To become a theoretical physicist ... you need to have a passionate love affair with the universe.

In fact, all of us have a piece of Chernobyl in our bodies going back to 1986.

[T]he yeoman's work in any science, and especially physics, is done by the experimentalist, who must keep the theoreticians honest.

The strength and weakness of physicists is that we believe in what we can measure. And if we can't measure it, then we say it probably doesn't exist. And that closes us off to an enormous amount of phenomena that we may not be able to measure because they only happened once. For example, the Big Bang. ... That's one reason why they scoffed at higher dimensions for so many years. Now we realize that there's no alternative.

I agree, along with Carl Sagan, that we should eventually become a two planet species. Life is too precious to place on a single planet.

There is so much noise on the Internet, with would-be prophets daily haranguing their audience and megalomaniacs trying to push bizarre ideas, that eventually people will cherish a new commodity: wisdom.

In general, the larger the breeding population, the slower the rate of evolution.