We explore because we are human and we want to know. I hope that Pluto will help us on that journey.

If you lined up all the cars in the world end to end, someone would try to pass them.

It is no good getting furious if you get stuck. What I do is keep thinking about the problem but work on something else. Sometimes it is years before I see the way forward. In the case of information loss and black holes, it was 29 years.

When I get to heaven I'm gonna find the guy in charge of the weather and kick his rear.

I want to know why the universe exists, why there is something greater than nothing.

When I was first diagnosed with ALS, I was given two years to live. Now 45 years later, I am doing pretty well.

[On President Bush's plan to get to Mars in 10 years] Stupid. Robots would do a better job and be much cheaper because you don't have to bring them back.