By Diana Steele
Science fiction movies and books are full of parallel universes.
In a typical scenario, as in the movie Sliding Doors, something happens in one universe—like a woman misses a train—but in a parallel universe, the same woman catches it, setting in motion diverging life paths.
Or, as in Isaac Asimov’s imaginative novel The Gods Themselves, alien inhabitants of a parallel universe with different physical laws exchange energy with our universe and send coded messages to Earth.