The Marvel Cinematic Universe is arguably responsible for making “multiverse” part of the everyday vernacular of millions of people worldwide, but they didn’t create the idea. Multiverse theory, or the Many Worlds Theory as it was first known, was proposed in 1957 by a physicist named Hugh Everett. Before Everett, a man named Erwin Schrodinger came up with essentially the same idea. Everett was more scientific, and Schrodinger was more philosophical. Both had essentially the same idea, however.
You may have never heard of Everett but you probably know Schrodinger. This is the same guy with the famous cat; that cat experiment is part of the groundwork for the Multiverse itself. Part of Schrodinger’s experiment involves not knowing whether the cat in the box is alive or dead. You can see how this starts to lead into a multiverse theory already. Maybe it’s dead in one universe and alive in another.
Part of the key to understanding Schrodinger’s experiment is that when you open the box to look at the cat to see whether it’s alive or dead, there’s nothing scientifically unsound about the idea that the other outcome could have been true.
Also, on paper, it’s scientifically sound if the other outcome occurs. So, in extremely dumbed-down terms that are missing a lot of steps, nothing is saying that a different universe where things play out differently couldn’t exist. Welcome to the multiverse. But is it real or just a theory?
The Multiverse
Since Everett’s time, other scientists have taken on the Multiverse theory to propose the idea. It’s not strictly the realm of superheroes and sci-fi by any means, but the theory is certainly controversial. Like any good scientific theory to explain something esoteric, it’s rooted in what we know about science with a healthy dose of conjecture and supposition. There is no evidence to suggest this is real. But there’s not a lot of evidence to suggest it’s not real.
In some ways, you can think of the multiverse like a tiger in the bathroom. If a guest in your house tells you there’s a tiger in your bathroom, your natural inclination is to immediately say, “Of course there isn’t.” But you don’t know, do you? Not with 100% certainty. You’ll never know for sure unless you look into it. And if for some reason you can’t get to the bathroom to check, you’re never, ever going to know with 100% certainty no matter how impossible it seems.
There are several different approaches to the idea of the multiverse. The Cosmological Multiverse Theory suggests that, immediately after the Big Bang, as the universe exploded into being it created all these bubbles. Each one is its own universe slightly separated from the main universe that birthed it. Over billions of years this potentially infinite number of bubbles all developed in their own way so some could be almost exactly like ours, and others could be unimaginably different and completely uninhabitable. Our universe would be just one of these bubbles.
String theory also allows for the idea of a nearly infinite number of parallel universes, each one developing in almost any imaginable way with just slightly different parameters each time.
To go back to Everett and his Many World theory, he believed in a quantum multiverse. In simple terms, the universe is constantly splitting. That means when you go to have breakfast and decide between pancakes or waffles, when you choose pancakes this universe continues while a new one splits in which you chose waffles.
Part of what is inherent to the idea of the Multiverse theory is that we can’t see or understand these other realities. They’re completely separate from our own. That, of course, makes it difficult to prove they exist. As to why anyone would believe they exist if there’s no way to observe them, that’s a little easier to explain.
The concept of a Multiverse can explain a lot of things for us. Science doesn’t know what it doesn’t know. What caused the Big Bang? Why does time flow the way it does? Why do all the scientific constants that we understand as being essential to reality exist as they do?
If a Multiverse exists, it can help us understand why things work the way they do in our universe. It’s entirely possible we got lucky and all of these things are just the subtle variations that managed to come together to create a functional universe while, in a different universe, nothing but chaos reigns because they were unlucky compared to us.
Arguments for Multiverse
It’s all well and good to suggest that a Multiverse may exist, but what evidence is there? What science could possibly support this idea? There’s more than you might think, especially if the Avengers and Spider-Man are your only links to the idea.
One argument for a multiverse is based on what we think we understand about space itself. If space is infinite, then the multiverse has to be real. There are only so many ways you can arrange matter and in an infinite space at some point matter would be arranged the same way more than once. So our world, our reality, has to have been repeated almost exactly again and again and again as well as in vastly different ways again and again and again. Infinite space is very big, after all.
A deck of cards is used as a visualization for how this makes sense. You can shuffle a deck of 52 cards in only so many ways. At some point, patterns emerge. Will the exact same 52 come out in order, eventually? Yes, actually, but smaller strings will happen, too. You’ll get the same three or four or five in a row again and again and again.
Hand in hand with the Big Bang Theory for the start of our universe is the theory of inflation that the universe expanded out, doubling size 90 times in the smallest fraction of a second you can even imagine.
Inflation is one of the most well-accepted theories about the origins of the universe and explains a lot, but it leads us back to the bubbles we talked about earlier. Some parts would expand faster than others and where it slowed down these bubbles would form. Those would be the little pocket universes and there could be an infinite number of them as well.
There is even potentially visible evidence of multiverses, but this is still in the realm of theory. Physicists in Europe studying Cosmic Microwave Background radiation left over from the formation of the universe itself spotted something unusual in 2010. There are visible, circular patterns in this background radiation. It’s been theorized that those patterns represent what you might call bruises from where other universes actually bumped into our own.
One of the more interesting arguments for Multiverse Theory proposes that our universe isn’t even a real one, it’s just a simulation. Based on what we know about computers, it was theorized that an advanced race, aliens or future humans, could build a computer so powerful that it would be able to simulate every human mind that ever existed. In fact, it could simulate far more than ever existed and do so very easily.
Oddly worrisome is that this theory, if it’s logically sound, lends itself to its own reality. The odds are actually in favor of it being true and for us never being aware because we’d be programmed to not know it. The upside is that, fundamentally, it would never affect our day-to-day lives.
Another argument for the existence of a Multiverse lies in the absolute complexity of our own. Think of how many things have to come together to make our universe work the way it does. Not just what had to happen for life to form on Earth, but how the forces of gravity have to work to allow a sun to burn as brightly, as warmly, and as long as it does. How subatomic forces need to work to hold atoms together. How molecules have to interact to allow for the complex chemical reactions that create livable environments, atmospheres, and so much more. It’s an infinite number of things that need to work together absolutely perfectly. This is sometimes called the “fine-tuning” argument.
Based on all that complexity, the multiverse theory offers a novel answer. Most universes don’t work. Life can’t happen, planets can’t form, and nothing can work the way we know it. But because there are infinite potential universes, some will have to work and ours is an example.
There is actually an abundance of other arguments in favor of the existence of a multiverse. Some are extremely complicated, some are definitely more philosophical. Some might even contradict others, but they all show a willingness by physicists and other scientists to try to explain what we experience every day by looking well beyond what we can see.
Arguments Against the Multiverse
Let’s start with that last argument – our universe is so vastly complex and unlikely to exist that there’s a good chance it’s just a lucky roll in a multiverse of duds. While you can understand the logic of it, others have argued it commits a version of the gambler’s fallacy. The idea is that a gambler, after losing all night, believes their next roll of the dice has to be a winner because they’ve lost so many times. Except there’s nothing in the odds that support that idea.
By the same token, nothing about why our universe works the way it does requires an infinite number of other failed or lesser universes to explain it. Whether they all exist or none exist has no relation to ours at all, so the argument is meaningless. By that reasoning, you cannot infer a multiverse.
A similar argument against this brand of Multiverse Theory can be summarized as likening it to faith. If the fundamentals of our universe are so complex and so seemingly impossible that we need to propose an infinite number of other less-perfect universes to explain our own, is this not very much like theology? None of it can be proven, so you must take it on faith that the multiverse blessed us with our more or less perfect universe.
It’s the inability to infer or prove a Multiverse that is the biggest problem with any of these theories. Take inflation creating these little bubble universes. Every time inflation slows down a Big Bang happens and a new universe is created in that bubble. There could be Big Bangs happening over and over again. But we know from our universe that we don’t know anything about before the Big Bang or outside of our universe. We can’t test these ideas. They are beyond the laws of physics as we know them in our universe.
The multiverse theory, while helping to explain many issues with quantum physics, also creates entirely new problems that reach levels of absurdity. If an infinite number of realities exist, then any preposterous thing could be happening in any one at any time.
There could be a universe where the sun explodes for no reason. There could be one where dinosaurs survived and are our masters. There could be one where you’re mulling over this argument right now but you’re also a very intelligent penguin. Stupid? Maybe, but the multiverse has to support it.
Still, when it was said and done, one of the biggest arguments against the Multiverse today is much the same as it was when the theory was first proposed. For any theory to be proven true, you need to be able to test it. It is completely impossible to do that with Multiverse Theory.
In the end, what you have is a bit of a stalemate. There are plenty of arguments that could support the existence of the multiverse. There are also plenty of arguments that take the wind out of its sails. We have no evidence of any kind to suggest the Multiverse is real, nor do we have anything to conclusively deny that it exists.
What we do have is one reality that we currently exist in. We have as much practical proof as we need that we exist, that our universe exists, and that’s what we have to deal with. Until some scientific breakthroughs occur that challenge the laws of physics, that’s all we’re going to have as well.