The End of the World As We Know It?

All this week, we've been talking with our friends from Scientific American about endings — how cultures fade, and natural resources dwindle. Today, we’re focusing on something even bigger: the end of human life as we know it — in other words, the apocalypse. The question of course, is how will it happen? Nuclear war? a killer virus, or perhaps an environmental disaster? John Matson, online news reporter for Scientific American, has been talking with specialists from a wide range of scientific backgrounds about the end of the world, for a story called "Laying odds on the apocalypse." Together, they’ve placed odds on a variety of doomsday scenarios. He speaks with us about what they found.