You may see a cup of tea fall off a table and break into pieces on the floor... But you will never see the cup gather itself back together and jump back on the table. The increase of disorder, or entropy, is what distinguishes the past from the future, giving a direction to time.

I think [contacting an alien civilization] would be a disaster. The extraterrestrials would probably be far in advance of us. The history of advanced races meeting more primitive people on this planet is not very happy, and they were the same species. I think we should keep our heads low.

Humanities deepest desire for knowledge is justification enough for continuing our quest. and our goal is nothing less than a complete description of the universe we live in.

Save water. Shower with your girlfriend.

What I have done is to show that it is possible for the way the universe began to be determined by the laws of science. In that case, it would not be necessary to appeal to God to decide how the universe began. This doesn't prove that there is no God, only that God is not necessary.

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?

My first popular book, 'A Brief History of Time,' aroused a great deal of interest, but many found it difficult to understand.