If the individual is to be happy in the contemporary order, he must be open-minded with respect to new values and new arrangements.

Loyalty to the family must be merged into loyalty to the community, loyalty to the community into loyalty to the nation, and loyalty to the nation into loyalty to mankind. The citizen of the future must be a citizen of the world.

Symmetries are the playing field on which the physical world works and which determine the rules of the game. The symmetries of nature determine for us things that remain constant, that can't be changed. Those are the guideposts in physics, the quantities like energy and momentum.

It's hardly a secret that I'm skeptical of declarations that the aliens are out and about on our planet. Still, I try to answer every one of these mails and phone calls because, after all, it's not a violation of physics to travel from one star system to another.

Comedy's about things the way they are. It's about the world as it is, not the world as we would like it to be, and science is the same, really.

To the extent that we even understand string theory, it may imply a massive number of possible different universes with different laws of physics in each universe, and there may be no way of distinguishing between them or saying why the laws of physics are the way they are. And if I can predict anything, then I haven't explained anything.