There are too many accidents that can befall life on a single planet.

One can see from space how the human race has changed the Earth. Nearly all of the available land has been cleared of forest and is now used for agriculture or urban development. The polar icecaps are shrinking and the desert areas are increasing. At night, the Earth is no longer dark, but large areas are lit up. All of this is evidence that human exploitation of the planet is reaching a critical limit. But human demands and expectations are ever-increasing. We cannot continue to pollute the atmosphere, poison the ocean and exhaust the land. There isn't any more available.

What was God doing before the divine creation?

Time travel used to be thought of as just science fiction, but Einstein's general theory of relativity allows for the possibility that we could warp space-time so much that you could go off in a rocket and return before you set out.

When I get to heaven I'm gonna find the guy in charge of the weather and kick his rear.

If we ever do find a complete theory of the universe, it would be a great triumph of human reason but it wouldn't leave much for us to do. We need an intellectual challenge.

Someone told me that each equation I included in my book would halve the sales. I did put in one equation, Einstein's famous equation, E = MC squared. I hope that this will not scare off half of my potential readers.