Warning: Spoilers inside! The very concept of dark matter is one that has a lot of scientists scratching their heads. It is at the center of quite a lot of hypotheses and could provide a key insight into the very nature of the universe itself (how it began, how it functions, etc.). There's just one nagging problem: We're having a hard time finding the stuff. Well, a bunch of scientists have put forth a possible explanation that will be familiar to any fan of science fiction: a parallel universe. But is such a thing even possible? Universe Today This is still a hypothesis, so a lot of testing and peer review is needed before we can get anywhere close to calling this a fact. Still, it's a tantalizing possibility, and it could radically alter our fundamental understanding of existence itself. If this does turn out to be true, though, we might want to be careful about any attempts at making contact with our parallel selves. Who knows what kind of facial hair they'll be rocking?