How civilization could destroy itself -- and 4 ways we could prevent it

Humanity is on its way to creating a "black ball": a technological breakthrough that could destroy us all, says philosopher Nick Bostrom. In this incisive, surprisingly light-hearted conversation with Head of TED Chris Anderson, Bostrom outlines the vulnerabilities we could face if (or when) our inventions spiral beyond our control -- and explores how we can prevent our future demise.