Ask courageous questions. Do not be satisfied with superficial answers.

The prediction of nuclear winter is drawn not, of course, from any direct experience with the consequences of global nuclear war, but rather from an investigation of the governing physics.

The chief deficiency I see in the skeptical movement is its polarization: Us vs. Them - the sense that we have a monopoly on the truth; that those other people who believe in all these stupid doctrines are morons; that if you're sensible, you'll listen to us; and if not, to hell with you. This is nonconstructive. It does not get our message across. It condemns us to permanent minority status.

The old appeals to racial, sexual and religious chauvinism to rabid nationalist fervor, are beginning not to work.

A galaxy is composed of gas and dust and stars - billions upon billions of stars. Every star may be a sun to someone.

Every thinking person fears nuclear war, and every technological state plans for it. Everyone knows it is madness, and every nation has an excuse

The suppression of uncomfortable ideas may be common in religion or in politics, but it is not the path to knowledge; it has no in the endeavor of science. We do not know in advance who will discover fundamental insights.