While parallel universes are a staple of science fiction, there are some real scientific theories to support them. But if parallel universes do exist, could we ever travel to them? It certainly wouldn't be easy, but let's explore this possibility.
Parallel universes crop up in two places in physical theories. One is in our conception of inflation, the theory of the extremely early universe. In those tumultuous times, many universes may have inflated all at once (and kept going) and branched out into a tremendous number of individual universes, each with their own kinds of physics and arrangements of matter. But traveling to the other universes wouldn't be easy, because they're far beyond our observable horizon and moving away faster than the speed of light. That would take a lot of frequent flyer miles.
