What If We Proved Parallel Universes? | Unveiled

What If We Proved Parallel Universes?

One of quantum mechanics’ more eye-catching theories is the Many Worlds Interpretation. It states that for any decision or measurement made in our world, there are branches made into other worlds where the other possibilities - the other decisions and measurements - happen instead. If it’s correct, then it means there are countless universes in existence alongside this one… but they’re always out of sight for us.

So, this is Unveiled, and today we’re asking the extraordinary question; what if we proved parallel universes?

The notion of parallel universes may seem like pure science fiction, and yet it comes up a lot in real-world science - especially in theoretical physics. According to the physicist Brian Greene, speaking on a 2011 edition of the National Public Radio talk show Fresh Air, we “can’t avoid having some version of the multiverse in [our] studies if [we] push deeply enough”. Yes, parallel universes perfectly lend themselves to the crazy, zany, colourful world of sci-fi… but serious, academic science invariably tends to point us in their direction, too, no matter how unbelievable it can seem.

Importantly, there’s as yet no direct evidence that these extra universes are there, but most theories do tend to arrive at similar conclusions. For example, one commonly held idea on the shape of the universe states that it should be flat and infinite… which would lead to a variation of the Many Worlds Interpretation, as it implies an overriding structure in which every possible atomic arrangement could eventually exist many times over. String theory, perhaps our most prominent attempt at a Theory of Everything, also arrives at a theoretical, higher landscape of potentially endless universes… this time via a kind of multi-dimensional membrane.

At present, we are searching for direct signs that any of our Many Worlds models could be true. With string theory, in particular, some versions include a way for us to check for any other universes that could be out there. Within the string theory / membrane structure, there’s a chance that particles could break free from their home membrane… to either float in the void between, or to infiltrate another membrane. And perhaps to infiltrate ours (i.e., enter our universe). If we could detect those particles, then we’d know without doubt that parallel universes exist. But equally, we can try to track those particles as they leave us. If a particle were to leave our universe, then we could count that now-absent particle as an energy loss… which is something that should be far easier to notice and measure. It’s why, when scientists smash particles together in particle accelerators, amongst everything else they’re searching for, they look for signs of lost energy… because that could indicate that a particle has escaped our universe, and perhaps headed for another one.

There are other methods in this quest to capture proof of parallel worlds, too. Some hope to find stronger evidence by studying the cosmic microwave background radiation, which is the leftover radiation in this universe from the big bang. If another universe were to have ever collided with ours, for example, there would likely be some form of scar in the CMB. And if we were to identify that scar, then we’d know that there was at least one other universe for ours to contend with. Alternatively, there’s the fine-tuning problem to consider, which is the realisation that this universe is so precisely and perfectly balanced to allow for life… that it can’t have been a one-off. The chances are that there must be others out there with far less favourable conditions, that are much more volatile. Supporters say that, in this way, the existence of a multiverse helps to explain one of the greatest problems of all; why we’re here.

It’s clear, then, that were we to prove that parallel universes exist, it would bring about a paradigm shift in the way humanity thinks about its own existence. And the implications for our lives would be immeasurably massive. It’s, of course, possible that if there are infinite parallel universes, then there are some that are totally different from our own… and some that are almost exactly the same. As well as everything else in between. Therefore, there could be endless versions of you out there, each one mostly similar but also slightly different. The classic representation of this is that in one world you have brown eyes, and in another you have blue. Or blonde hair turns to red. But the points of potential difference could really be infinite. Perhaps you’re exactly the same, except your voice is one tone deeper, or your favourite colour is green instead of yellow, or the eyelashes on your left eye are ever so slightly shorter.

Naturally, it all depends on how many universes could exist. But, in one study, the Stanford physicists Vitaly Vanchurin and Andrei Linde calculated that as many as ten to the power of ten, to the power of ten, to the power of seven could be possible… This is just an incredibly high number, and greater than the human brain can even truly process. So, maybe we should expect such a comically specific, near-endless line of new versions of ourselves, so as to include one with even an eyelash’s worth of difference. And then, it would be the same for everyone else. And for everything else. And, for all the tiny changes that could take place, there would also be huge, sprawling changes, too. Parallel universes where the laws of nature are completely different, where the rules of matter are totally upended, and naturally many, many worlds where humans don’t exist, at all. Where life of any kind hasn’t even begun to become possible.

Broadly speaking, our imagination is the only limit. And various academics have proposed models for this. In MIT cosmologist Max Tegmark’s Mathematical Universe Hypothesis, mathematics is the key… transcending nature itself, to build everything in this universe and the multiverse. For the Harvard philosopher, Robert Nozick, the Principle of Fecundity is crucial, which bluntly argues that all possible universes exist. If they can be thought of, they can be. Which is a fun idea when you consider what it could mean for fictional universes; that everywhere from Narnia to Hogwarts to Middle-Earth actually exists, somewhere. To bend the implications even further still, it could mean that the dream scenes we all conjure up while sleeping also exist… somewhere. These are also figments of our imagination, but with proven parallel universes they could be true facets of reality, as well.

Of course, proving parallel worlds is one thing, but accessing them would be another. At best it would be extremely difficult, at worst it could be impossible. Much depends on the true structure of what reality is. If this universe truly is infinite, then we could have a quilted universe on our hands. This term, popularised again by Brian Greene, refers to the multiversal existence of every possible arrangement of particles… only everything is at least contained within one overriding structure. So, all we have to do to access this type of multiverse is travel far enough in the right direction. Most likely via wormholes.

If the many worlds of a multiverse are separated, though, such as with bubble or membrane universes, then it’s an even more difficult task… wherein we’d need to somehow bridge the momentous gap. We’d need to work out how to hop between this universe and another. But, again, it would all hinge on exactly how the multiverse we’d now proven to be real was built, and how it was born.

Ultimately, finding proof of parallel worlds - if they exist - will be extremely tough. And, most likely, even if science was to make a major breakthrough, it would take years (maybe centuries) before it was accepted as a fundamental fact. Proving the multiverse would serve to shake the boundaries of our reality, probably more so than anything else ever before. Not only would it dramatically change how we saw our own selves as human individuals, but it would also change how we viewed the Earth as a whole, the Milky Way Galaxy, and it could also completely alter our ideas about Faith and God.

Because now, even the immensity of the universe will have shifted, even the intricacy of life itself will have altered… humankind would know not only that there were other worlds out there, but also that there were other constructs containing even more worlds, with an even greater level of otherness about them. How would you feel living in a time of such enlightenment? Because that’s what would happen if we proved parallel universes.