Physicists often quote from T. H. White's epic novel The Once and Future King, where a society of ants declares, "Everything not forbidden is compulsory." In other words, if there isn't a basic principle of physics forbidding time travel, then time travel is necessarily a physical possibility. (The reason for this is the uncertainty principle. Unless something is forbidden, quantum effects and fluctuations will eventually make it possible if we wait long enough. Thus, unless there is a law forbidding it, it will eventually occur.)

Physicists are made of atoms. A physicist is an attempt by an atom to understand itself.

I want to see us to explore outer space. But I want to do it safely, without the loss of human life, and democratically: where is the free-wheeling debate on this question? Only one force can stop this mission: the will of the American people. They have not been asked. Do they want to endanger their loved ones, their industry with this launch? One force is more powerful than plutonium, the spirit of the American people united.

I realized very early in life what my abilities and limitations were, and foreign languages was definitely one of my limitations. With strenuous effort, I just barely passed my French class at Harvard so I could graduate.

My point is, no one can stop the Internet. No one can stop that march. It doesn't mean that it's going to be smooth, though.

I don't. We've had three technological revolutions that have changed the course of human history, all driven by physics. In the first, the industrial revolution, physicists developed Newtonian mechanics and thermodynamics, which gave us the steam engine and machine power. The second technological revolution was the electricity revolution. That gave us radio, television, and telecommunications. Then, physicists developed the laser and the transistor.

It's pointless to have a nice clean desk, because it means you're not doing anything.