By improving health, empowering women, population growth comes down.

Don't let complexity stop you. Be activists. Take on the big inequities. It will be one of the great experiences of your lives.

I've for some reason or other... never met Donald Trump.

Security is, I would say, our top priority because for all the exciting things you will be able to do with computers - organizing your lives, staying in touch with people, being creative - if we don't solve these security problems, then people will hold back.

The part of uranium that's fissile - when you hit it with a neutron, it splits in two - is about 0.7%. The reactors we have today are burning that 0.7%.

If I had one dollar left, I'd spend it on PR

The year I was born, 1955, the first big disease-eradication program in the world was declared for malaria. After about a decade of work, they realized that, at least in the tropical areas, they did not have the tools to get it done.