In the end, it's the people who are curious who change the world.

If you are that person, you are more likely to believe that God cured you, this invisible force, creator of the universe, cured you, than that you had three idiotic doctors diagnose you. ... I taught physics to pre-med students who became doctors. Not all of them are smart, I assure you.

Even with all our technology and the inventions that make modern life so much easier than it once was, it takes just one big natural disaster to wipe all that away and remind us that, here on Earth, we're still at the mercy of nature.

Let us not fool ourselves into thinking we went to the Moon because we are pioneers, or discoverers, or adventurers. We went to the Moon because it was the militaristically expedient thing to do.

We are only intelligent by our own measures

The Earth is just one place of many that we could hang our hats.

The solar system should be viewed as our backyard, not as some sequence of destinations that we do one at a time.