The ultimate arbiter of truth is experiment, not the comfort one derives from one's a priori beliefs, nor the beauty or elegance one ascribes to one's theoretical models.

If we wish to draw philosophical conclusions about our own existence, our significance, and the significance of the universe itself, our conclusions should be based on empirical knowledge. A truly open mind means forcing our imaginations to conform to the evidence of reality, and not vice versa, whether or not we like the implications.

The ultimate goal of physicists is to arrive at an equation that explains everything and could fit on a t-shirt. That may happen but the t-shirt would have to be 10-dimensional.

When a person's religious beliefs cause him to deny the evidence of science, or for whom public policy morphs into a battle with the devil, shouldn't that be a subject for discussion and debate?

If our species is to survive, our future will probably require outposts beyond our own planet.

Whatever the evolutionary basis of religion, the xenophobia it now generates is clearly maladaptive.

We now know that we are more insignificant than we ever imagined. If you get rid of everything we see, the universe is essentially the same. We constitute a 1 percent bit of pollution in a universe . . . we are completely irrelevant.