All Aboard the 21st Century!

Our Person of the Century issue is still a couple of months away, but we thought we'd get a head start on the next century by launching the first in our new five-part series, Visions 21. The idea of the series is to probe the next century by asking 100 provocative questions and then doing our best to answer them. This week we explore the first 20 questions, about our health and the health of our planet.

Unlike a lot of writing about the future, Visions 21 is not science fiction. As journalists, we're more comfortable asking questions than making predictions,...