Do parallel worlds ever cross paths? (Photo: Martin Brigden/flickr)

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, such as the Copenhagen interpretation and the many-worlds interpretation.

Now there’s a new theory on the block, called the “many interacting worlds” hypothesis (MIW), and the idea is just as profound as it sounds. 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, reports RT.com.

The theory is a spin-off 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.

“The idea of parallel universes in quantum mechanics has been around since 1957,” explained Howard Wiseman, a physicist at Griffith University in Brisbane, Australia, and one of the physicists to come up with MIW. “In the well-known ‘Many-Worlds Interpretation’, each universe branches into a bunch of new universes every time a quantum measurement is made. All possibilities are therefore realised – in some universes the dinosaur-killing asteroid missed Earth. In others, Australia was colonised by the Portuguese.”

“But critics question the reality of these other universes, since they do not influence our universe at all,” he added. “On this score, our “Many Interacting Worlds” approach is completely different, as its name implies.”

Wiseman and colleagues have proposed that there exists “a universal force of repulsion between ‘nearby’ (i.e. similar) worlds, which tends to make them more dissimilar.” Quantum effects can be explained by factoring in this force, they propose.

Whether or not the math holds true will be the ultimate test for this theory. Does it or does it not properly predict quantum effects mathematically? But the theory is certain to provide plenty of fodder for the imagination.

For instance, when asked about whether their theory might entail the possibility that humans could someday interact with other worlds, Wiseman said: “It’s not part of our theory. But the idea of [human] interactions with other universes is no longer pure fantasy.”

What might your life look like if you made different choices? Maybe one day you’ll be able to look into one of these alternative worlds and find out.

The idea of parallel worlds is one of the more favorite topics of science fiction writers, but also a popular subject of interest for many researchers. If you watched the Fringe series, you will remember that there were two simultaneously existing versions of the same world with slight differences between them. It seems that something like this could be possible, according to a new quantum theory.

A group of Australian and US physicists suggests that there may exist multiple versions of our universe, which can interact with each other on a quantum level. Dr. Howard Wiseman and Dr. Michael Hall of Griffith University in Australia, together with Dr. Dirk-Andre Deckert from the University of California, published their so-called “Many Interacting Worlds” (MIW) theory in the journal Physical Review X.

It is a known fact that quantum mechanics display strange phenomena which violate the principles of cause and effect. That is why it is so difficult to explain the nature of these phenomena. “Any explanation of quantum phenomena is going to be weird, and standard quantum mechanics does not really offer any explanation at all–it just makes predictions for laboratory experiments,” Dr. Wiseman wrote in an email to the Huffington Post. “Our new explanation…is that there are ordinary (non-quantum) parallel worlds which interact in a particular and subtle way.”

The new theory is an alternative to the ‘Many Worlds’ concept, which was proposed in 1950s by American physicist Hugh Everett to explain the ability of quantum particles to be in two states simultaneously. He suggested that both states co-exist in different realities, that is why quantum particles can seemingly occupy two places at once. Thus, in accordance with the ‘Many-worlds interpretation’ hypothesis, each version of reality branches into a bunch of new realities, which exist separately and can’t interact with each other. From this point, the “Many Interacting Worlds” theory is totally different, as it speculates that multiple universes can overlap and influence each other.

There are three key points to understanding the MIW theory: first, there is a gigantic number of universes, some of which may be nearly identical; second, all of these universes are equally real; third, there is a force of repulsion between similar universes, which is a cause of quantum interactions between them.

“The beauty of our approach is that if there is just one world our theory reduces to Newtonian mechanics, while if there is a gigantic number of worlds it reproduces quantum mechanics. In between it predicts something new that is neither Newton’s theory nor quantum theory. We also believe that, in providing a new mental picture of quantum effects, it will be useful in planning experiments to test and exploit quantum phenomena,” Wiseman noted.

In spite of some negative criticism, such as the article by Czech physicist Luboš Motl in which he called the MIW approach “a hopeless enterprise and a huge waste of time,” prof. Wiseman and his team are optimistic about the prospects of their research: “I think there are many who are not happy with any of the current interpretations, and it is those who will probably be most interested in ours. I hope some will be interested enough to start working on it soon, because there are so many questions to answer.”

The biggest challenge now is to come up with the ways to test this hypothesis and find the indications of possible interactions with other universes. As for the possibility that someday humans might establish contact with other universes, Dr. Wiseman said: “It’s not part of our theory… But the idea of interactions with other universes is no longer pure fantasy.”