Home Technology The Multiverse, explained by a quantum physicist

The Multiverse, explained by a quantum physicist

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This past weekend, a couple of my friends and I went to see Everything Everywhere All at Once. I went in knowing two things about it: The first was that the very talented and fantastic Michelle Yeoh was in it; and the second was that it involved the “multiverse.”

As the credits rolled, with tears trickling into my mask, I had a hard time discerning what was making me emotional. I say emotional because it wasn’t just one feeling, but a strange mix of several: joy, wistfulness, catharsis, yearning, hope.

Without giving too much away, the very simple gist of this maximalist, fantastic tornado of a movie is about the choice to exist, to fully live within the present moment. It’s about finding the beauty in our small, odd lives, even as we constantly compare what we have to our unfulfilled fantasies. The movie also examines how we take solace in the personal disasters we’ve narrowly avoided. But what makes Everything Everywhere All at Once so powerful is the multiverse, a dazzling antidote to the fact that real life these days feels like it’s been designed to blur and pummel our emotions into dullness.

Michelle Yeoh in Everything Everywhere All at Once.
Courtesy of A24

What is the multiverse? A world full of endless potential; multiple parallel universes spinning in synchronicity; and the possibility of alternate, powerful, seemingly better versions of ourselves. At a time when a pandemic, wars, and political cruelty have become constant, inevitable presences in our daily lives, it’s the ultimate fantasy for this moment. And that’s not just because Marvel, the most powerful entertainment company in the world, has gone all-in and made the multiverse a cornerstone of its current storytelling.

Rather, Marvel is just one take, one depiction of a limitless and alluring fantasy that’s impossible to pin down. Movies like Bill and Ted’s Excellent Adventure, Back to the Future, Sliding Doors, About Time and even It’s a Wonderful Life have all played with the idea of alternate or parallel timelines and futures.

In an attempt to better understand why I was so moved by Everything Everywhere All at Once and also ascertain just how realistic the idea of the multiverse is (and ostensibly how invested I should be in the idea of a better, more successful me existing in a non-pandemic timeline), I reached out to Spyridon “Spiros” Michalakis, a mathematical physicist at the California Institute of Technology. He studies how the universe works at a quantum level, and actually served as the science consultant for Marvel’s Ant-Man, a movie about a man who can shrink, and who can also affect space and time.

Which is to say, Michalakis’s scientific knowledge informed Marvel’s multiverse. While he possesses a vast understanding of physics that dwarfs mine — at several points in our chat I told him he was absolutely blowing my mind — it was his very human understanding of the multiverse and the hope it presents to worn down, burned out humans that made me understand it, and, I think, my own post-movie delirium, better.

Thanks for speaking with me. I know you’re busy and have World Quantum Day tomorrow!

Absolutely! The multiverse is my bread and butter. In fact, I may be responsible for it.

Wait, elaborate — what do you mean responsible?

I’m the science consultant for Ant-Man and I introduced the quantum realm there. Then it was also in Ant-Man and the Wasp, and then Avengers: Endgame and everything else. So you’re talking to the right person.

Perfect! Wow, look how that worked out.

So as you know, the multiverse in Marvel is based in the idea that there’s a central timeline, but every decision made — more or less — sprouts off new timelines. Everything is constantly breaking off from that central timeline. Could you talk a little bit about your initial ideas of the concept, and how you infused what you know from science into it?

The irony of all of this, is that the multiverse may have emerged literally from the tiniest of places. When I consulted with Paul Rudd and Peyton Reed, they wanted to know what happens when you shrink.

I think if you really shrink — this gets really interesting — you get to the source code of reality itself. That’s what the quantum realm is. Space and time just don’t operate the same way at that level. I tried to infuse the movies with as much actual science as possible. At some point, the writers were more excited about the real science than the hocus pocus-like stuff.

When it comes to the multiverse, apparently quantum physicists prefer science over “hocus pocus.” Said hocus pocus is being performed by Doctor Strange in Spider-Man: No Way Home.
Courtesy of Columbia Pictures

No offense to Doctor Strange.

Yes! No offense!

The multiverse emerged from there, from the fact that you have a very basic concept in quantum physics known as quantum superposition. Quantum superposition basically says that what we think of as a single universe, the quantum superposition, is the interference of an infinite number of universes. Each one of them has different things that are happening at some microscopic level. When you zoom out from our microscopic human perspective, we get to see certain patterns like space and time and matter emerge, and particles that have some more definite positions, in both space and time.

Marvel took to heart the idea that we can use the quantum realm to reverse-engineer that single universe and split it apart into threads, and then explore each of these timelines individually, for dramatic effect.

I want to ask you about “real science.” Is it super silly for me to think that there’s a different Alex in another alternate universe? Or is that a leap too far?

I really do think that this is absolutely what is going on.

Oh no! What if there’s a better Alex somewhere?

No, you’re the very best version of every Alex ever.

Wait. How do we know that? Are you just being nice?

Because I just said so, and that’s all that matters.

But I do want to know — what we see on screen is one thing, but what’s the actual science like? Can you please explain it to me in the simplest way possible?

Have you heard about the double slit experiment, one of the famous quantum experiments?

I majored in English. I most definitely have not.

This is one of the famous quantum experiments, before quantum was even a thing. This gave us an inkling for the first time in human history that something was amiss with the way we thought about the universe.

We thought you could shoot single electrons or photons, just single particles, toward a wall where you had put two slits. They could go either on the left side or the right side, through the slit, and then hit a wall behind it.

Got it.

You can imagine, like bullets or billiard balls, a bunch of them would either go through the right slit or through the left slit. Then you would see, on the back wall, a bunch of them hitting the right or the left. They actually tried to do that experiment, and what they saw was that on the back wall, you did not have the pattern you expected.

You had waves — you had the electron or the photon going through both slits at the same time, interfering with itself behind that wall, and then hitting the other wall as if it was a wave.

Think about it like you have water waves going through these two slits, and then you can see the crests rising and falling, depending on how the interference flows. That’s what was happening with actual physical particles, one at a time.

I think I got it — the outcome wasn’t expected, and everything, including the probability, was off. Full disclosure: The last time I took physics was in college.

A rock with google eyes sitting on the dirt.

Michelle Yeoh (as a rock) in Everything Everywhere All At Once.
Courtesy of A24

So, they’re thinking: How the hell is it possible that one thing was going through two places at the same time?

Then, [Nobel Prize-winning physicist] Richard Feynman was like, Wait a minute, what if we had a third slit, and the fourth one, and the fifth one?

Sure enough, you would see an even more complex pattern in the back as if the electron was going through all four or five of them at the same time. He realized, wait a minute, if you keep making slits, at some point, the wall with all the slits disappears and becomes just the empty space through which light and matter travels anyway.

It travels through everything — it takes every path, at all times. It’s actually a perfect analogy to the title of the movie. Like, the title of the movie is scientifically accurate.

Everything Everywhere All at Once?

That is exactly how the universe works. Space and time are one single, singular construct. There’s not like you have space and then time; it’s space x time. Moreover, quantum space time is a superposition: a quantum superposition of an infinite number of space times, all happening at the same time.

This illusion — basic physical reality — is the fact that human beings have very specific points of view, ways of observing the superposition.

We all agree that, like, there’s a car in front of us, or a screen we’re looking at, or that somebody’s talking. Other points of view, though, you can access using quantum computers. We’re developing those things, at places like CalTech, where you tease that apart, where you get to see underneath the hood of reality.

I think I got it!

You get it? That’s impressive.

I mean, I get it in very broad terms. Basically, if we all have the same perspective, we share a view on reality and how we see the world. But, based on your perspective or point of view, that could easily change. Like that wall with the slits!

Exactly. Exactly.

And you wouldn’t know about those other perspectives, right? That’s the beauty of this. You wouldn’t know, unless you’re also flickering between two different realities. Which can happen also, because again, the frame rate of the human mind is so low relative to the frame rate of the universe, right?

Holy shit. What? Frame rate? So, like humans are missing an entire sequence?

Let’s say we only perceive 100 frames per second, something like that. We can be aware of our lives and choices we make, but then the frame rate of the universe where you could be flickering between different timelines is 40 orders of magnitude above that. It’s one with 40 zeros.

Then we make the best approximation.

We’re all trying to figure out the plot of the universe by just watching the beginning and the end of the movie, the first and last frame. We’re just reconstructing the in-between the best we can. That’s where the multiverse hides; it hides there in between frames. Honestly, I think that the frame rate of the universe truly is infinite, not even finite, very, very large. And we’re so far away from that.

That missing movie comparison — my mind is absolutely blown.

The whole point, and what we’ve seen, is that our intuition just breaks so badly, so badly at every scale. We’re just missing most of it. But we try to make the best theories about it as we can.

What’s fascinating to me, listening to this, is that we’re all essentially blind-guessing — and again, I’m not a physicist so this could be way off. Obviously this is all relative, but I have my intuitions or guesses about how the universe works. You do too, and your knowledge dwarfs mine exponentially because of quantum physics. But then yours — your frame rate, intuition, your knowledge — is dwarfed by the infinite magnitude of the entire universe.

The universe is going like 100 million billion frames — exactly. Making fun of all of us.

I want to ask you, and I think you may have answered this implicitly, but why do you think everyone’s so fascinated with this concept?

First of all, from a franchise point of view, the Marvel Cinematic Universe has been probably the most successful movie franchise of all time.

And the multiverse is, at its foundation, its essence, a fresh perspective: What if I had made a different choice? What if time itself is not one-dimensional? What if it is a million-dimensional? What if you can jump left and right and up and down or just back and forth in time? And if you can do that, then it means you’re basically going to other realities — that may look very much like yours, or different.

Orbium Planetarum Terram

Andreas Cellarius was a Dutch-German celestial cartographer. Isn’t it funny that we can be like, “lol, actually sir, the universe thinks you’re way off!”
Buyenlarge/Getty Images

For scientists, we’ve become better at explaining concepts to our friends across the aisle on the entertainment and the Hollywood side. They feel more empowered to tell good stories, based on time travel and things in fiction like that, like the multiverse. They have the GPUs and now render these beautiful things: the multiverse, quantum realm, everything in between.

You know, being able to hop in the multiverse is also a superpower. It’s such a powerful visualization, to not just break the laws of physics in this universe, but to have almost infinite choice of who you are. To escape yourself and become someone else.

I think the key word here might be “fate.” A lot of storytelling wrestles with the idea of destiny and our choices, and whether we have control of our future. The multiverse seems like it offers a freedom from that, in that your fate could be anything that you choose, or whatever your quantum superposition is.

It’s the idea that you may not be aware of it, but there is a power of choice that you have at some microscopic level that defines your identity as a citizen of this reality, versus a parallel one: where your most important choices you made are kind of your fingerprint. This is what separates you from this other version of yourself. You made a different choice, and maybe you made the best of that other choice.

But the thing that is also pretty powerful is the possibility that you could learn from the other versions of you. What if you could meet them, and all of a sudden, you realize that you have all these latent powers, potential within you, that were actually explored? And they flourished in this other reality.

What if you were a spy over there, or a fantastic cook, or an amazing writer? Or all the things you may have wanted to become, or even better — what if you could be all these things you thought you would never be good at? It’s a fantasy of your best self.

The reason why this is so important, and why I was trying to introduce these ideas, is that the dream of these possibilities makes such a huge difference when everything is going to shit around the world. I’m not gonna go political, but you know what I mean: everything in the pandemic, and now what’s happening in Ukraine.

At some point, there’s a really tempting choice to just be cynical and say there’s nothing I can do and that no version of me makes a difference here.

I want people to know — especially young people trying to figure out where they fit in this world — that they have power to make anything happen, and make that world where they can do amazing things. They can really take control and become that version of themselves that unlocks their true potential.

I get that. I feel like the buzz phrase over the past two years has been “existential crisis.” There’s been a general feeling of like, I don’t know why this matters. What does it even matter if I exist?

The multiverse fantasy, to me, feels like the inverse of that. There’s something beautiful in the idea of existing everywhere all at one time. The idea that this life, your life, everything everywhere matters so much right now.

There is something very powerful about just knowing, even though you may not know how, but just knowing that something is possible. Often it’s heroes that are the ones that first believed something was possible, and that fate was not set. Just knowing, or at least believing so strongly that something is possible, then allows you to mess around and experiment and figure out how to actually make it possible.

That’s what science tries to really do. It takes a science-fiction idea, something humanity would love to be true, and then says, let’s try to understand. First, we have to believe it’s possible, then try to understand what we need to tweak in our understanding to get to this new point.

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