I believe everyone should have a broad picture of how the universe operates and our place in it. It is a basic human desire. And it also puts our worries in perspective.

Disorder increases with time because we measure time in the direction in which disorder increases.

However difficult life may seem, there is always something you can do and succeed at.

Not to leave planet Earth would be like castaways on a desert island not trying to escape...Sending humans to other planets ... will shape the future of the human race in ways we don't yet understand, and may determine whether we have any future at all.

Women. They are a complete mystery.

Someone told me that each equation I included in the book would halve the sales.

Once I wept for I had no shoes. Then I met a man with no feet, so I took his shoes. I mean, it wasn't as if he was going to need them.