# Scientists Propose that Parallel Universes Are Not Parallel

Parallel universes are a staple of science fiction, and by definition should not have any contact or interaction with our known universe. But a new study from Griffiths University shows that several well-known quantum effects, such as entanglement and interference with a double slit, can be explained by these "parallel" universes colliding with each other.

Quantum mechanics leads to several experimental "oddities," so to speak, that lead to seemingly paradoxical conclusions. For example, experimentally demonstrated interference with a double slit seems to indicate that quantum particles travel on all possible paths, but then all of those paths collapse into one single event once the outcome is observed. In other words, the observation seems to determine past events. A common explanation for this phenomenon involves a version of the multiverse theory, in which every observation causes all the other outcomes that were not ultimately observed to branch off into parallel universes, one for each possible outcome. There are several criticisms of this theory, chief among them that different outcomes occur with different probabilities, which means that the multiverse hypothesis must assert that certain universes somehow take precedence over the others.

Physics professors Howard Wiseman and Dr. Michael Hall from Griffiths University and Dr. Dirk-André Deckert from the University of California propose a radical rethinking of the multiverse hypothesis, one in which there is "a fixed, although truly gigantic, number of worlds. All of these exist continuously through time – there is no 'branching,'" Wiseman wrote in The Conversation. Furthermore, all the effects observed by quantum mechanics only occur as a result of interaction between universes; "indeed, if there were only one world in our theory, it would evolve exactly according to Newtonian mechanics, not quantum mechanics." So according to their theory, our universe does not operate according to the wave function, which exists in infinite dimensional space, but exists only in three-dimensional space.

From the paper: "Our 'many-interacting-worlds' approach hinges on the assumption that interactions between deterministically evolving worlds cause all quantum effects. Each world is simply the position of particles in three-dimensional space, and each would evolve according to Newton's laws if there were no interworld interactions."

According to Wiseman, this theory solves the probability objection, because "each one of our worlds is equally real. Probability only enters the theory because an observer, made up of particles in a certain world, does not know for sure which world she is in, out of the set of all worlds."

The research team asserts in their paper that their theories may lead to new ways of thinking about quantum mechanics, including the possibility of unifying it with gravity, the holy grail of theoretical physics. "Thus, while Richard Feynman may have had a point when he said 'I think I can safely say that nobody understands quantum mechanics,' there is still much to be gained by trying to do so."

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