Nearly every time travel theory offered by physicists, such as black holes, wormholes, or multiple universes, has been taken up by storytellers. Time travel gives good box office; Arnold Schwarzenegger will reportedly get $30 million to star in the third Terminator film. Time travel makes for a nifty plot device, a catalyst that works across genres, including comedy, romance, horror, fantasy, and detective story; in the film Time after Time, H.G. Wells himself chases Jack the Ripper through 1970s San Francisco. In print, Bradbury, Dick, Heinlein, and their successors filled the shelves with time-travel variations. But the greatest success may have come to a romance writer. Diana Gabaldon has reached the bestseller lists several times by sending the 20th century heroine of her Outlander bodice-ripper novels into the arms of 18th-century hunky Scotsman Jamie Fraser.
Which brings us to the present. This month we can enjoy the curious fact that Dreamworks' remake of the classic 1960 film The Time Machine is directed by H.G. Wells' great-grandson, Simon Wells. It retains the original film's Victorian decoration-a time traveler in tweed vest, a time machine with brass fittings and steam-era dials-as well as the Hollywood happy ending: Handsome Guy Pearce battles Morlocks in 800,000 A.D. and gets the girl, although both the girl and the special effects have been spectacularly jazzed up. As fascinated as he was by the conundrums of time travel, Simon Wells says he knew the darker end-of-history aspects of the original novel would not yield a blockbuster; he pitched the movie as "an essay into the nature of causality in which we blow a bunch of stuff up."
This is what the good time travel stories and the physics share: interest in the nature of causality. Time travel yields paradoxes with the narrative power of Greek myth, causing scientists to ask questions like, "What would happen if you journeyed back in time to kill your grandfather before you were born?" Well, a good story would happen, and that's what fuels the time travel fiction. What fuels the scientific interest is that time, since Einstein, has been entwined with the problems of gravity, quantum mechanics, and the search for a unified theory of everything. And time travel-into the past, where the paradoxes spring up-appears not to be in conflict with the laws of the universe.