Elon Musk, the Tesla and Space-X founder who is occasionally compared to comic book hero Tony Stark, is worried about a new villain that could threaten humanity?specifically the potential creation of an artificial intelligence that is radically smarter than humans, with catastrophic results:

Musk is talking about "Superintelligence: Paths, Dangers, Strategies" by Nick Bostrom of the University of Oxford's Future of Humanity Institute. The book addresses the prospect of an artificial superintelligence that could feasibly be created in the next few decades. According to theorists, once the AI is able to make itself smarter, it would quickly surpass human intelligence.

What would happen next? The consequences of such a radical development are inherently difficult to predict. But that hasn't stopped philosophers, futurists, scientists and fiction writers from thinking very hard about some of the possible outcomes.