What is the multiverse?

If you’ve ever gazed up at the stars, knowing that you are only seeing a tiny fraction of our galaxy, and then realized the Milky Way is just one galaxy amongst billions of galaxies, you may have felt awe. Or maybe you felt impossibly small.

If the vastness of the night sky did in your head, you might not want to read the rest of this little über-précis of the multiverse.

For me, the scale of the Universe is a thing of wonder, and when I started to dig into multiverse theory, that amazement grew. Just like the way our universe inflated after the Big Bang – racing out from its initial point to the expanse that’s now 14 billion light-years in all directions. (Even that fact blows my mind.) We can’t even see everything in our universe, but there are good reasons to believe that this iteration of the Big Bang, the one that has allowed our existence, isn’t all there is.

That’s the multiverse. Everything that is.

There’s a variety of ways to think about this, and I’ll attempt to outline them in layperson’s terms, as best I can.

How thinking about this stuff, and then writing it feels. Thanks to GIPHY for this and the other gifs.

First: a caveat on the science behind multiverse theory

I have to be up front on this – I am not a physicist. I did okay in my grade 13 calculus class – and even better in my grade 12 physics class — yet not well enough to continue on in the sciences during my undergrad. But I love big ideas, especially the what ifs that spin off of cutting edge science. And really, this is the biggest “what if” there is. So, I’m going to actual reference other people in this piece, so you know I’m not just making this shit up. And I’ll tell you when I am confabulating.

The physics alone will blow your mind

Earlier I mentioned cosmic inflation theory. This idea basically says that when our universe was really young – less than a second old – the universe expanded rapidly. Cosmic inflation was confirmed in the 1990s, 2000s and 2010s. It’s a thing. (1)

But inflation didn’t end. Imagine a bubble spawning off another bubble. And then another. Sometimes there’s more than one at a time. These new bubbles of space – what we would call the visible universe — are at such a remove from us, they are impossible to see. (2) But is there proof of this? Sort of: it’s called the anthropic principle.

The anthropic principle

So, this concept is actually the evidence of this first inflation theory. If there are an infinite number of other universes with different physical laws, then it stands to reason, that some of those universes would have physics that allowed for the development of life. And if that develops, then there could also be some forms of life that would develop consciousness. This principle seems pretty self-absorbed, but I dig it. Consciousness – subjectivity – seems pretty essential to me and others. (3) The nature of consciousness is at the heart of my novel, Alpha Max, but I’ll try to keep to the multiverse for now.

This anthropic principle is still an hypothesis. It’s fundamentally non-scientific because we can’t measure any of this, beyond our understanding of the physical laws of our universe, what we can see from the evidence, and so on. Some scientists even believe this is not a legitimate topic for scientific inquiry, but the history of science should be a lesson to them. At this point it’s educated guesswork. Advanced guesswork with mathematical models of probability I can’t even begin to understand. So, yes, we can’t measure any of this ”¦ yet. (4)

But some ideas have been falsified

Quantum gravity, is an idea that unites Einstein’s theory of general relativity with quantum mechanics. So, as a universe collapses – the “Big Crunch” – at the end of time, a new baby universe comes out on the other side, leading to multiverses. This theory has less validity, as it seems like the Big Crunch isn’t likely to happen. I have no idea, I’m going with Ethan Siegel on this one too. (5) (And if you love this stuff, you should definitely read his pieces on Forbes that talk about the multiverse.)

That leads us to the stuff that got me all fired up to write Alpha Max”¦

Ta Da! The Many Worlds Interpretation of quantum mechanics

The Many Worlds Interpretation (MWI) is where the multiverse gets really jiggy! This is the one that says there are infinite parallel universes all existing at the same time and place.

Wait, but are they parallel? Many are, but many are different because of what has happened before – there are infinite varieties of earths, all changed because of billions of human beings, throughout history, making choices. Somewhere there’s an actual world that may look a lot like PK Dick’s in The Man in the High Castle. There’s a world where Napoleon won the Battle of Waterloo. (My guess is there can’t be too many of those.) There’s a world where human beings never evolved to become the most successful, and destructive, species on Earth.

This is the conceptual multiverse that the novel Alpha Max inhabits and that restricted my world-building, but the interpretation can be pushed farther. In essence, this interpretation suggests that every mathematical possibility exists – so worlds that have different physical laws, in addition to multiple realities based on superposition. (6)  

Confused yet? Good. Here’s another way to think about it all

MIT physicist and mouse-champion, Max Tegmark, has created a helpful taxonomy of these ideas. In his work, he suggests there are four tiers, which he outlines in a great Scientific American article. (7)

Level 1: It’s Out There

So, this takes the idea of expansion and postulates that because the Universe is infinite (or practically so), then there is a probability that somewhere very far away, there is a duplicate of you reading this bad explanation of the multiverse. How far away? I don’t know. I don’t have the math to even begin to describe it. You’re probably way smarter than me, so check out Tegmark’s article link in the footnotes.

Level 2: Infinite Bubbles

This also depends on cosmic inflation theory, which again, is pretty much a proved thing. So, in addition to there being duplicates of you super far away, there are also other level 1 multiverses out there that are in different bubbles of reality in a massively vast empty space.

Hey, I told you this was going to get existentially challenging.

Level 3: Why does it always have to be a six-sided dice?

This tier takes the idea of quantum mechanics, and plays out the scenario that Schrödinger made famous with his cat. You know this one. The cat is both alive and dead (in a superposition) until we observe it. But this theory takes this one step farther. The superposition creates Universes. In one Universe I threw a 1 on the die, and in another 6. They all exist.

Ironically, even though this level is based on the total weirdness of quantum mechanics, I think this is the one we can instinctively understand. This is the one Community knocked out of the park, imho.

Level 4: Gonzo

Okay, we’re really reaching the limits of my understanding with this one. Essentially, Tegmark is saying that how these other Universes operate may be completely different, so they have different physical laws. He uses Platonic and Aristotelian models to describe them, and I’m just going to quote him directly:

According to the Aristotelian paradigm, physical reality is fundamental and mathematical language is merely a useful approximation. According to the Platonic paradigm, the mathematical structure is the true reality and observers perceive it imperfectly. In other words, the two paradigms disagree on which is more basic, the frog perspective of the observer or the bird perspective of the physical laws. The Aristotelian paradigm prefers the frog perspective, whereas the Platonic paradigm prefers the bird perspective. (8)

Max Tegmark

We certainly experience the world on an Aristotelian level, but reality is much weirder than that, knowing what we know about quantum theory. So, even if we are frogs, we may need to imagine ourselves as birds.

Isn’t this becoming philosophy?

Well, in Tegmark’s Nature article, “Many lives in many worlds” he argues that it may be. BUT, he also says that if we ignore these out-there theories because they seem so weird and strange, then we are missing the opportunity to learn from them. And he says they are falsifiable. They just haven’t been falsified yet.

Playing this out in fiction

So, Alpha Max is an attempt to put all of these ideas in a novel. We get to meet many different versions of Dr. Maximilian Tundra who have all made different choices in their lives, leading to different outcomes and worldviews. This was really fun to do at the character level, but the book was also a sandbox for worldbuilding. Mostly, I just played around with history and society – which was perfect for talking about the existential dangers we faces such as climate change and nuclear war. I kept these alternate universes pretty tame, so I didn’t create any universes with homicidal cutlery and magic llamas.

But now that I think about it ”¦

Wait! What about the Omniverse and Metaverse?

The Omniverse is all multiverses combined. Omni=all. So that means everything, even all our fictional universes. That’s right, so somewhere out there Batman is buying Spider-man his first beer.

The Metaverse really doesn’t have anything to do with this stuff. It’s a hypothetical version of the internet that is 3-D, and includes virtual and augmented reality. Terrifyingly, it’s also now the new company name of Facebook.

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Notes:

1) Siegel, Ethan. 2021. “What Is (And Isn’t) Scientific About The Multiverse”. Forbes. https://www.forbes.com/sites/startswithabang/2018/07/17/what-is-and-isnt-scientific-about-the-multiverse/?sh=7df6ccea25c4.

2)”What Is Multiverse Theory?”. 2021. Livescience.Com. https://www.livescience.com/multiverse.

3) “Anthropic Principle – Wikipedia”. 2021. En.Wikipedia.Org. https://en.wikipedia.org/wiki/Anthropic_principle.

4) Siegel, Ethan. 2021. “What Is (And Isn’t) Scientific About The Multiverse”. Forbes. https://www.forbes.com/sites/startswithabang/2018/07/17/what-is-and-isnt-scientific-about-the-multiverse/?sh=2fac083725c4.

5) Siegel, Ethan. 2021. “Ask Ethan: Can The Universe Still End In A Big Crunch?”. Forbes. https://www.forbes.com/sites/startswithabang/2017/05/13/ask-ethan-can-the-universe-still-end-in-a-big-crunch/?sh=4fb907b04347.

6) I’m gonna’ go ahead and note that many physicists don’t really use the term multiverse. They just say Universe, because the Universe encapsulates all the possible variations of it. But I don’t find that so helpful for the layperson.
Many-Worlds Interpretation of Quantum Mechanics (Stanford Encyclopedia of Philosophy) “Many-Worlds Interpretation Of Quantum Mechanics (Stanford Encyclopedia Of Philosophy) “. 2021. Plato.Stanford.Edu. https://plato.stanford.edu/entries/qm-manyworlds/#WhatWorl.

7) Tegmark, Max, 2003. “Parallel Universes.” Scientific American. https://space.mit.edu/home/tegmark/PDF/multiverse_sciam.pdf

8) Tegmark, Max, 2003. “Parallel Universes.” Scientific American. p. 49. https://space.mit.edu/home/tegmark/PDF/multiverse_sciam.pdf

9) Tegmark, Max, 2007, May. “Many lives in many worlds.” Nature. p. 23-24. https://space.mit.edu/home/tegmark/PDF/everett2.pdf

10) “Metaverse – Wikipedia”. 2021. En.Wikipedia.Org. https://en.wikipedia.org/wiki/Metaverse.

Galaxy photo by A K from Pexels