The multiverse is here, there, and everywhere, in fiction and quite possibly in real life. We know, this is quite a lot to digest, considering everything you once knew about life and how it operates is now in question.
We’ll back up…
Have you ever wished you were living a life different than the one you’re living? What if that was an actual possibility, but you couldn’t see or experience it? Would it still be your life?
Let’s leave the philosophical and existential questions for a moment and look at the science. Actually, first let’s look to one of the greatest tools for escapism that unquestionably exists: “fiction.”
The concept of multiverses has always existed in movies and TV shows. It has exploded in terms of popularity in recent years, appearing everywhere from dramas like Netflix’s Stranger Things to blockbusters like those in the Marvel Cinematic Universe. Even sitcoms like Community have utilized it before.
What is the multiverse, though, scientifically speaking? What do popular fictional portrayals get right? Let’s dive in!
What Is The Multiverse?
The whole multiverse concept is based inside (you guessed it) the world of mathematics. We heard all your groans. However, math isn’t just about numbers and facts. It can actually be used for quite a bit of creativity, and offers us a fascinating world of possibilities instead of just things set in stone!
Multiverses start, like we all probably did, with the Big Bang. A single point fittingly called a singularity, expanded and expanded. In fact, the universe is still expanding.
That single singularity, however? It’s also expanding into multiple, potentially infinite, singularities. Hence, there are potentially worlds where you don’t exist, and an equal number of worlds where you do. All of this takes place inside multiple different universes.
Within these infinite universes, time is just another dimension. Rather than being the unstoppable march slowly guiding us all towards our inevitable deaths, time might be merely a way in which we experience the realities of our universe. Other universes, however, might exist outside of time.
What do we mean by “time as just another dimension?”
Time Travel: Background To The Multiverse
Some, like a scientist you might have heard of by the name of Albert Einstein, theorize that time and space are connected. Space has three dimensions (we all know about 3D). Rather than a dimension that exists entirely separately from 3D space, Einstein theorized time can combine with 3D to create fourth-dimensional spacetime.
How is math involved? Pull out your high school science books and turn to the most well-known equation in history: E=MC2. Einstein’s theory of relativity is key to spacetime. Essentially, time is dependent on speed (the speed of light, in the famous equation).
If time itself depends on something else, then it isn’t a constant. In fact, experiments show that we can control the rate and speed at which we travel through time.
Hence, theoretically, the concept of time travel emerges. Well, presuming humans are able to figure it out before the unstoppable slow march of our experience of time brings us to death and our planet with us.
Time is also dependent on gravity. The further away from Earth that you get, the less “time” affects you. As gravity was connecting you to the “time” of the planet. Yes, truly. Einstein’s Theory of Relativity equations suggests that gravity bends spacetime. It’s known as gravitational time dilation.
Time and Gravity:
Further experiments support this theory too. Clocks in satellites orbiting Earth run faster than their Earthly counterparts.
For a fictional example, let’s look at the 2014 movie Interstellar, famous for its scientific accuracy. It features a planet that exists near a Black Hole. As a result, this planet is affected by the supreme gravity of the black hole. Our protagonists land and spend only a few minutes on the planet before they notice mountains moving toward them.
Spoilers: they aren’t mountains. These are waves. By the time two of the three make it back to the shuttle, though? It has been twenty-three years for their companion who stayed with the shuttle. However, it was almost no time for them. He aged, but they haven’t. Our characters technically sped into the future, right?
Time travel into the future is certainly possible. To travel to the past, though? That might arguably be impossible, but there’s no way to say for sure.
In the meantime, we have the timeless time-travel concept in fiction. From Back to the Future to Outlander & Doctor Who, the idea of traveling back in time fascinates us as humans. Key to all these stories, however, is the notion that traveling back can change the present.
In Back to the Future, Marty’s changes threaten to make him not even exist!
Yet if Marty made himself not exist, then he could not have existed to create his own nonexistence. This is what one would call the “grandfather paradox.” However, this is only if one could go back in time within the same universe. Our heads hurt, so we won’t go deeper here except to say that this is the key to understanding the concept of the multiverse!
Choices & The Butterfly Effect
The idea of one small decision causing an untold amount of consequences is known as the butterfly effect. The name comes from the idea that if a butterfly flaps its wings in New York, this motion creates a tiny breeze. This wave of air might create a cyclone in Japan. The butterfly effect applies to more aspects of life than just multiverse theories, too.
Remember the sitcom Community, where Abed imagines various timelines? Depending on which character goes downstairs to get the pizza, the future changes. Besides spawning one of the greatest memes of the Internet age, season 4, episode 3’s “Remedial Chaos Theory” illustrates the infinite possibilities of multiple universes.
When multiverse theory combines with theories like the butterfly effect, various timelines emerge. In some timelines, characters die. In others, they leave. Some timelines are positive for the characters and some are negative.
What if each moment, though, is its own singularity? Well then, not even all the math textbooks that ever existed can count how many universes there might be. Everything Everywhere All at Once explores dozens of potential universes for its main character.
This includes universes where she ends up with different partners and one where she is actually a rock instead of a human.
The Schrödinger’s Cat concept was coined by Edward Schrödinger, not the Cait Sith from Final Fantasy. Don’t worry, fellow cat lovers, no cats were harmed in the creation of this theory. Well, not in this timeline anyways.
Basically, Schrödinger’s theory is based on quantum mechanics, which we’ll get into in a bit.
For now, let’s connect the theory to choice again. By observing something, you are forced to make a choice. A cat exists in a box. By opening the box, you determine whether it cat is alive or dead. In one universe, that choice might result in it being alive, but in another, it could be dead.
By opening the box, you’ll discover whether it’s alive or dead. However, it cannot be both alive and dead (unless this timeline has zombies, of course). You cannot know for sure until you open the box. Depending on the timeline or universe you’re in, the cat could be alive or dead.
Quantum Tunneling And The Multiverse
To discuss quantum, we’re going to have to get a bit physics-y. Essentially, when broken down to their smallest bits, building blocks of our world like particles and waves don’t actually behave like two separate things. Instead, they behave like each other.
Hence, scientists coined the aptly-named “uncertainty principle.”
The uncertainty principle states that we can’t measure both an object’s physical position (related to particles) and speed (related to waves) at the same time. Schrödinger actually took a break from musing about cats to come up with an equation for this.
You might have already gathered this, but the thing about quantum particles is that they don’t behave as we’d think at all. They often do not follow even the most basic of scientific rules. Quantum tunneling shows us that when quantum particles bounce off an energy barrier, they sometimes cross the barrier in spite of the fact that they really shouldn’t.
Scientists have no idea how they do this.
Quantum particles need significant energy to do this. Remember how in Stranger Things, transferring to and from the Upside Down (a parallel world) requires a lot of energy?
When particles cross these barriers, they might be in two places at once. Quantum tunneling potentially holds the key to accessing alternate universes. In theory, we shouldn’t be able to travel between universes. However, quantum particles sometimes do cross barriers in defiance of logic.
Hence, what’s to say people can’t? Well, currently a lot, but we’re talking theoretically.
There is a great example in the world of fiction where quantum tunneling is used to go back in time. In Avengers: Endgame, the universe’s greatest heroes use quantum tunneling to send Captain America and others across time and space barriers to defeat Thanos.
Many fictional stories delve into a specific type of universe in the multiverse that is not part of the one we’re in. We refer to this as a “parallel universe.” These parallel universes are almost the exact same as ours and exist alongside our universe, yet even minor differences in that universe can eventually lead to a completely different universe from ours.
Due to the fact that these universes exist in different dimensions, we aren’t aware of them. A mirror you could be reading this very article right next to you, right now, and you wouldn’t know!
Star Trek‘s famous “Mirror, Mirror” episode has the Enterprise crew meet versions of themselves from a mirror world. Unfortunately, the mirror crew is made up of evil versions of our beloved characters! This episode is so loved and praised that the Mirror Universe reappears in other versions of Star Trek.
In Stranger Things, the Upside Down is also a parallel universe, because it exists as a version of our own universe. The Upside Down doesn’t have evil versions of our characters. Instead, it is poisonous. Well, at least when the plot requires it to be.
Of course, not all possible universes are parallel universes. However, you might be shocked to learn that scientists believe parallel universes might actually exist In 2019, scientists began experiments to see whether they could create mirror versions of those quantum particles. There have been some interesting developments since this began.
String Theory & The Multiverse
At this point, we’ve established inconsistencies in math, science, time, speed, and our basic understandings of the universe. What could explain all of these? String theory! We know, you’ve likely heard this used by films or books to explain everything away. Most of the time, it was used to just help them escape from having to make a complicated story.
Yet you might be wondering, what exactly is String theory and how does it relate to the multiverse?
These strings are found throughout the universe and interact with each other. Mass, charge, and other properties are affected by the vibrational state of the strings. One of the strings connects to gravity, thereby connecting it to quantum gravity.
Due to the potential answers that it provides for science, many claim it is one of the main candidates for the infamous “theory of everything.”
It’s actually way more complicated than this simplistic explanation, obviously. In fact, scientists have been arguing about the nuances and specific equations for decades now. There’s a good chance we’ll be studying it for decades to come too.
Still, other scientists argue that string theory isn’t even a valid theory. After all, if a theory’s basis is that there’s pretty much an infinite number of possibilities, then you can’t disprove the theory. If you can’t disprove it, is it really science? Some might claim that if you cannot disprove it, then it is valid as a theory until disproven.
The Multiverse Of Possibilities
Ray Bradbury, an American science fiction writer, once said:
science fiction… is the art of the possible, never the impossible.
Are multiverses limited to fiction, or are they real? Well, we don’t know. Still, there is enough science to say that multiverses are definitely possible.
Stories take us on time travel journeys, show us vast possibilities, and give us a chance to do things we can’t do in this timeline. They are enjoyable, exciting, and not as far from reality as we might think. There could even be universes where the fictional stories we watch are real.
It’s not surprising that so many stories are jumping to explore the multiverse. The possibilities are fascinating, after all. Someday, maybe another version of you or me will wander into our universe and make it all clear, or we’ll wake up as a rock, or the Upside Down will invade us.
Until then, scientists and stories will keep exploring our universe and maybe others one day.