I have sold more books on physics than Madonna has on sex.

Gravity is so strong that space is bent round onto itself, making it rather like the surface of the earth. If one keeps traveling in a certain direction on the surface of the earth, one never comes up against an impassable barrier or falls over the edge, but eventually comes back to where one started.

If I had to choose a superhero to be, I would pick Superman. He's everything that I'm not.

Before we understand science, it is natural to believe that God created the universe. But now science offers a more convincing explanation.

In real time, the universe has a beginning and an end at singularities that form a boundary to space-time and at which the laws of science break down.

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

Doing a job RIGHT the first time gets the job done. Doing the job WRONG fourteen times gives you job security.