Quantum mechanics, though firmly tested, is so weird and anti-intuitive that famed physicist Richard Feynman once remarked, "I think I can safely say that nobody understands quantum mechanics." Attempts to explain some of the bizarre consequences of quantum theory have led to some mind-bending ideas.

Now there's a new theory called the "many interacting worlds" hypothesis (MIW). The theory suggests not only that parallel worlds exist, but that they interact with our world on the quantum level and are thus detectable. Though still speculative, the theory may help to finally explain some of the bizarre consequences inherent in quantum mechanics.

The theory is a spinoff of the many-worlds interpretation in quantum mechanics — an idea that posits that all possible alternative histories and futures are real, each representing an actual, though parallel, world. One problem with the many-worlds interpretation, however, has been that it is fundamentally untestable, since observations can only be made in our world. Happenings in these proposed "parallel" worlds can thus only be imagined. MIW, however, says otherwise. It suggests that parallel worlds can interact on the quantum level, and in fact that they do.