The United States is not longer going to be the world's policemen and our days of determining you're in or you're out around the world no matter what the level of direct American interest or connection are going to be very limited. Increasingly, Africa will be doing that.

We live in a fantastically wealthy country. We don't have to worry about food. We don't have to worry about clothing. We don't have to worry about our safety. It's very easy for me to be an environmentalist. It's very easy for me to care about making sure that we protect the forests and the whales, and all that stuff.

There is too large a divergence at the moment in the interests and values of the world's most powerful states.

I think it's fantastically narcissistic to believe that in the entire universe, with all of the planetary systems that we've already discovered and the countless others that are out there, that we are the only forms of life. Now, the real question is not are there other forms of life out there, but are there other intelligent forms of life out there right now. Because the universe is not only really big but it's also really long. It's been around for a long time; it's going to be around for a long time.

The two world wars boosted American power and devastated potential rivals to an extent that could not have lasted more than a few decades.

Sometimes you check things off because you've done them. If you aren't checking stuff off your bucket list, you aren't living very well.

I think that the environment is very a complicated question. I am very sympathetic to people who support the environment who live in the United States. I am very sympathetic to people who don't support the environment who live in a very poor country.