Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?

One does not have to appeal to God to set the initial conditions for the creation of the universe, but if one does He would have to act through the laws of physics.

Our only chance of long-term survival is not to remain lurking on planet Earth, but to spread out into space.

Observations indicate that the universe is expanding at an ever-increasing rate. It will expand forever, getting emptier and darker. Although the universe doesn’t have an end, it had a beginning in the Big Bang. One might ask what is before that but the answer is that there is nowhere before the Big Bang just as there is nowhere south of the South Pole.

In effect, we have redefined the task of science to be the discovery of laws that will enable us to predict events up to the limits set by the uncertainty principle.

Keeping an active mind has been vital to my survival, as has been maintaining a sense of humor.

Although September 11 was horrible, it didn't threaten the survival of the human race, like nuclear weapons do.