The universe doesn't allow perfection.

Remember to look up at the stars and not down at your feet. Never give up work. Work gives you meaning and purpose and life is empty without it. If you are lucky enough to find love, remember it is there and don't throw it away.

I had no desire to share the fate of Galileo, with whom I feel a strong sense of identity, partly because of the coincidence of having been born exactly 300 years after his death!

The idea of 10 dimensions might sound exciting, but they would cause real problems if you forget where you parked your car.

A theory is a good theory if it satisfies two requirements. It must accurately describe a large class of observations on the basis of a model that contains only a few arbitrary elements, and it must make definite predictions about the results of future observations.

Intelligence is the ability to adapt to change.

The increase of disorder or entropy is what distinguishes the past from the future, giving a direction to time.

There should be no boundary to human endeavor.

It surprises me how disinterested we are today about things like physics, space, the universe and philosophy of our existence, our purpose, our final destination. Its a crazy world out there. Be curious.

To confine our attention to terrestrial matters would be to limit the human spirit.

Not only does God play dice but.. he sometimes throws them where they cannot be seen.

My goal is simple. It is a complete understanding of the universe, why it is as it is and why it exists at all.

I don't think the human race will survive the next thousand years, unless we spread into space.

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

The thing about smart people is that they seem like crazy people to dumb people.

I had no desire to share the fate of Galileo, with whom I feel a strong sense of identity, partly because of the coincidence of having been born exactly 300 years after his death!

It is said that there’s no such thing as a free lunch. But the universe is the ultimate free lunch.

I don't think the human race will survive the next thousand years, unless we spread into space.

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

I like physics, but I love cartoons.