If there really is a complete unified theory that governs everything, it presumably also determines your actions. But it does so in a way that is impossible to calculate for an organism that is as complicated as a human being. The reason we say that humans have free will is because we can't predict what they will do.

Women. They are a complete mystery.

In A Brief History Of Time I used the word "God" like Einstein did as a shorthand for the laws of physics. However, this is not what most people mean by God, so I have decided not to use the term. The laws of physics can explain the universe without the need for a God.

A million million million million (1 with twenty-four zeros after it) miles, the size of the observable universe.

A zero-gravity flight is a first step toward space travel.

I don't have much positive to say about motor neuron disease, but it taught me not to pity myself because others were worse off, and to get on with what I still could do. I'm happier now than before I developed the condition.

Never put off the work till tomorrow what you can put off today.