There are ecosystems like coral reefs [at risk] through ocean acidification. Those are valuable things that we should protect.

In 1990, one in 10 children died before the age of five. That's now down to one in 20, and vaccines were the single biggest factor in that. Had it stayed at 10 percent, 122 million more children would have died.

At some point, that risk-taking private capital can take over, and have patents and trade secrets and things that let them lead the way, which happened with the steam engine and some other things, although with energy, the time of adoption is a lot longer than it is with, say, IT products or even medical advances, like drugs and vaccines.

In poor countries, we still need better ways to measure the effectiveness of the many government workers providing health services. They are the crucial link bringing tools such as vaccines and education to the people who need them most. How well trained are they? Are they showing up to work?

With world health, every life you save is a wonderful thing, so it's not this question of whether you solve it or you don't. The chance of completely solving the problems has long odds. But really, the thing is that you get to save the first child, the second child, the third child. You can just feel good about that.

The government is somewhat inept, but the private sector is inept in general. How many companies do venture capitalists invest in that go poorly? By far most of them. However, every once in a while a Google or a Microsoft comes out, so people keep giving them money.

When you develop software, the people who write the software, the developers are the key group but the testers also play an absolutely critical role. They're the ones who ah, write thousands and thousands of examples and make sure that it's going to work on all the different computers and printers and the different amounts of memory or networks that the software'11 be used in. That's a very hard job.