Universe not big enough for you? There’s always the multiverse — many universes, scattered through time and space. In one world, you might drive a bus; in another, you might be a Formula One racer. If the idea sounds familiar, that could be because it has obsessed science-fiction and comic-book writers for decades. But artists and writers aren't the only ones fascinated by multiples — some physicists think the multiverse could be very real.
(Originally aired December 10, 2015)