Types of Multiverse

So I recently watched the Imaginary Axis' Video "Marvel's Guide to the Multiverse." It's a good video and I would definitely recommend watching it:
https://www.youtube.com/watch?v=MAt0xpQe934

The Imaginary Axis is a Youtube channel I am a big fan of using Pop Cuture to discuss scientific, metaphysical, and philosophical arguments. I occasionally would argue with Tyler on minor points but for the most part I think he is very well informed of both the pop culture he is talking about and the scientific, metaphysical, and philosophical points he's talking about. Although obviously that's just me.

In his latest video he talked about Multiverse Types Briefly and I just wanted to make a quick (hopefully) blog partially responding to parts of his video but mostly wanting to give a slightly expansion by explanation in more detail what these types of multiverses are and what their implications. I will try and be brief and speak in layman's terms since I know some people don't possess the same interest in the most esoteric elements that I do.

He starts out with a very good point, that a lot of these are difficult to talk about partially because the terms are so ill-defined. As such I want to talk about the term "Universe" means for a second.

"Universe" comes from the Latin "Universus". "Uni-" means one and "versus" means "turned" so Universe means literally "Turned into one" or "Everything we perceive considered as one thing" And that leads to several different definitions of universe today.

One definition as my old Science teacher insisted is that Universe simply means everything. Obviously if Universe means everything there is no Multiverse, because you can't have Multi-Everything, as Everything consists of every individual thing.

The other common definitions are "a spacetime set and all within it" and "everything that we can percieve to the very edges of observable spacetime". The later is referred to the as the "Observable Universe". The most common definition seems to be the spacetime set one and so I will be using that and referring to the second as "Observable Universe" when I wish to refer to it. The observable Universe has a measure of 93 Billion Lightyears in diameter

The Universe itself has 3 general models with variations in each about what it's size and shape is. Finite, Unbounded, and Infinite.

Finite is the most obvious model. Spacetime has a definite size that may or may not be the same as the observable universe dimensions. What happens when you reach the end of space? Well because space and time are the same, it's the same as reaching the end of spacetime, which in this case is some kind of end to the universe, a big crunch or rip or freeze...nasty business for sure.

I'll get back to infinite in a second but first I want to talk about the Unbounded Model. It may sound strange at first since how could something be neither finite or infinite? Those are negations. Well the Unbounded model holds the universe in some regards but not in others. The most common depiction is that space curves so that if you go far enough eventually you will reach back to where you came from, sort of like a game of Pac-Man. It's like walking on the surface of a sphere, just not in 3-dimensions.

And then we have the infinite universe model. There is arguments for all 3 of these to be sure but this one probably raises the most questions for the typical person. If the universe is infinite and I go far enough will I ever run into another me? After all there is only a finite number of combinations of particles and infinite space so eventually I have to be duplicated. You are correct, hypothetical person. In an infinite universe, there is bound to be not just an exact copy of your observable universe right now, but an infinite number of copies. This brings me to the first of the 4 Rough Multiverse categories, all of which Tyler explained in his two Multiverse videos

Type 1: The Quilted Multiverse Theory
This is at least the name Tyler uses for it though this one in particular has many names. Now all 4 Multiverse Types have people arguing for whether or not they are true, and 3 of them have people arguing whether they are possible, or at all logical evaluations of the data.

However no one is arguing that this type is impossible. There are plenty who argue it's not true or real but it's physical possibilities is accepted by essentially everyone and it goes as follows:

Because an observable universe is by necessity finite, it's perfectly possible that one could have two "Observable Universes" in an overarching Universe. By having two "Observable Universes" one could have a "Multiverse". It's pretty simple, no?

Now I am very much into DC. I am not much into Marvel, although I believe I can say I have more information then the average person. As far I know, neither Marvel or DC have confirmed a Quilted Multiverse although neither have denied it. See any combination of these 4 types of multiverses are possible, ranging from none of them to all of them being true. They are independent of each other.

So it's possible though as far I know unconfirmed if there is a "Quilted Multiverse Theory" in either or both of Marvel and DC. The DC Universe I know has been confirmed to extend 100 Trillion Light Years from Earth so it definitely has room for such a Multiverse.

This brings up an interesting philosophical question, which is the distinction between a Quilted Multiverse Theory and an Unbound Universe. If you travel to an identical observable universe in this model then the you of that observable universe also traveled to an identical universe in the same direction which begs the question of it being in fact the same you and same universe. If the Universe is so big that it contains exact copies of the observable universe if you travel far enough, is it a copy or it actually the same thing?

Type 2: Bubble Universes
This theory holds that because of space's extension, little pockets form like bubbles which contain their own physical laws. What we perceive as our universe, our observable universe is merely the small patch in the original Singularity whose space has been so expanded that it is our Observable Universe.

This was done mostly to explain how come our universe seems to have such regular-ness if we come from an extremely chaotic Singularity of the Big Bang. Since the original Singularity at the moment of the Big Bang must have been intensely chaotic it doesn't seem to make sense that our universe would have uniform physical laws, but it could be we exist in a bubble that was formed from a small patch of the space of the singularity that has expanded to be our current observable universe.

This theory also holds generally that bubbles can combine or separate, much like physical bubbles we know. This is often done to explain certain oddities of our universe.

Type 3: Quantum Multiverse:
The most common Multiverse depicted in fiction due it's possibilities but also the one that makes physicists most uncomfortable. Commonly called the "Many Worlds Interpretation" this is the interpretation that the breakdown of phase space we perceive is not ACTUALLY a breakdown but instead us merely perceiving one possible outcome.

Their are two models: The Probabilistic Quantum Multiverse and the Ultimate Ensemble Quantum Multiverse.

For the first one imagine that we live in a video game, where the only thing that's loaded is where the players are because the game doesn't want to load the entire gameworld at once. Now when you travel to a certain spot a die is rolled. If it rolls a 6, there is a monster attack. The Probabilistic Quantum Multiverse suggest there are 6 "Universes" that emerge from this encounter:

A Universe where 1 is rolled: No Monster Attack
A Universe where 2 is rolled: No Monster Attack
A Universe where 3 is rolled: No Monster Attack
A Universe where 4 is rolled: No Monster Attack
A Universe where 5 is rolled: No Monster Attack
A Universe where 6 is rolled: Monster Attack!

But what if the die is weighted towards 6 so the chance of getting a 6 is 50%? In that case 10 "Universes" will emerge from the encounter:
A Universe where 1 is rolled: No Monster Attack
A Universe where 2 is rolled: No Monster Attack
A Universe where 3 is rolled: No Monster Attack
A Universe where 4 is rolled: No Monster Attack
A Universe where 5 is rolled: No Monster Attack
5 Universes where 6 is rolled: Monster Attack!

((OK, in fairness it's a LOT more then 6 or 10 universes. It's actually the same number in both cases...this is just the proportions. In the first 1/6 of the universes are Monster Attack, and in the second 1/2 of the universes are Monster Attack))

The alternative however comes from Max Tegmark's Concept of the "Ultimate Ensemble". That any set that can be mathematical expressed does in fact exist so long as it meats necessary physical conditions of a universe. In this case there are are an infinite amount of die roll universes. Infinite 1s. Infinite 2s. Infinite 3s. all the way to Infinite 6s and Monster Attacks.

Both Marvel and DC have this. DC's called "The Metaverse" is linked to their idea of "Hypertime" and the idea of Metafiction that runs throughout DC's Higher Dimensions. However DC also possess a Brane Multiverse as well (the two together are called Quantum Brane Multiverse...very creative I know). Before I watched Tyler's video I was not aware of Marvel having or not having this and at first from his explanation it seemed they didn't have a Brane Multiverse. And that's kind of a problem.

This is the thing that make a lot of physicists really uncomfortable with the Quantum Multiverse, in particular the Ultimate Ensemble. There are scientific objections but there is one argument that is a philosophical argument that takes it as true and has horrifying implications...the "Problem of Meaning"

The Problem of Meaning works as follows. If we define meaningful action as action that would have a consequence, IE an action that would result in a different cosmos even slightly if you didn't do it, then this type of Multiverse alone doesn't allow for ANY meaningful action.

If you save a baby's life in this Multiverse then there exists just as many universes where you did not. If you rob a bank in this Multiverse then there exists just as many universes where you did not. If you let yourself slowly die from inaction because you realize the futility of it all, there exists just as many universes where you did not. Every action you commit therefore has no meaning whatsoever. Free Will might still exist but only depending on how you define free will and regardless it can't make any impact. It's a very very sobering possibility if this is the correct view of the Multiverse. Tyler is right to call into question it's ontological implications. If the Avengers fail to stop Loki, does it matter?

Now he tries to explain away this problem in a strictly Quantum Multiverse and I give props for the attempt. It was noble and fairly strong but this is an extremely difficult problem for philosophers and I don't think his first response really explains it.

The first response is that there exists "Free Agents" that allow for some degree of meaningful impact, including travelers between two Universes, and A-Universal Beings.

Travelers between universes are beings that travel between universes and thus are causing a shift on a different universe. However this is insufficient to solve the problem since every decision they do in the other universe has as many universes where they did not. There are exactly as many universes where they didn't even travel to the other universe. Their impact can not solve the Problem of Meaning so long as all universes involve are strictly Ultimate Ensemble Quantum Universes.

The other proposed solution from within the Model is the A-Universal Beings. Beings that don't belong to a universe specifically but can impact them. While this is somewhat of a solution, it doesn't work based on that description of how they act. Example: The Living Tribunal. The Living Tribunal destroys universals which are bad. This may seem to give meaning, but since the same number of universals will become bad as before, this is not giving any meaning since within the universes there is the same number of bad outcomes as good outcomes.

However he then brought in information that made me quite happy personally

Type 4: The Brane Multiverse
This is the final Multiverse and the hardest to really understand but I will do my best.

Imagine a 3-Dimensional Cube like a die. Imagine the universe is one of the 6 "faces" of the die. The beings of the universe have a sense that their are other universes and moreover that the universes are arranged in some kind of larger "pattern" but can't grasp it.

You can extend this pattern into higher dimensions, and that's basically branes. That what we perceive as the observable universe is actually a "face" or aspect of a larger Higher-Dimensional Structure.

If you add Branes to a Quantum Multiverse then it automatically fixes the Problem of Meaning. You see if there is an object in higher-dimensional constant, then that adds a "Multiversal Constant". The minute you add a Multiversal Constant you change everything because suddenly even an Ultimate Ensemble Multiverse does not cover every possible permutation but instead has common traits.

This perhaps sounds very esoteric, so let me give you the example Tyler himself gives. Because something interesting turns up in Spider-Man comics. Here's the link for Tyler explaining it himself.

You know, Spider-Man has always been my favorite Marvel Hero, and a lot of people underestimate the important Spidey has to the Marvel Universe has as a whole. Spider-Man has come to act as the sort of collective conscious of the Marvel Universe, sometimes even the writers themselves. One good example is Civil War. Spider-Man starting out surprisingly joining Iron Man and the Pro-Registration side after much considerations since initially the Writers of Marvel wanted Civil War to be a grey conflict with arguments on both sides but ultimately favoring Pro-Registration. However as they contemplated this and realized overtime it went against everything they had stood for (not to mention had way better talent on the Anti-Registration Side) Spider-Man turned away from them and joined the resistance. Spider-Man changing sides essentially mirrored the Marvel Writer's change in what they believed. As this sort of councious of the more grey Marvel Universe, it makes alot of sense why people would be very shocked if Peter, oh I don't know, MADE A DEAL WITH THE DEVIL SELLING HIS MARRAGE AND RETCONNING THE PAST FOR HIS OWN MISTAKE! But occasional slip-ups aside Peter is to me the best example of Marvel at it's best, a person with only ever JUST enough time, energy, and power to do the right thing, always struggling to be responsible and take the world on without despair.

This is vaguely the core of Spider-Man. That he is always going to be scrapping by trying to do everything and yet will always do the right thing even if it means personal sacrifice and try and face the world with an optimistic grin. And it's this "Core" that leads to an interesting effect. In the "Spider-Verse" series, it's revealed that a Higher-Dimensional being called "The Great Weaver" deliberately makes it so that a Spider-Man entity, someone with that core (Plus Spider powers) appears in every universe in order to "keep the multiverse in check". Consider the implications.

There isn't a universe without a Spider-Man entity in the Marvel Multiverse (at least not the main one). Even if Spider-Man fails in one or more universes, his impact will always be there. He has made a meaningful impact on each universe for no other reason then because he is in each one. And because of what he is at his core, that impact for each universe is almost exclusively a net positive. Even if this was the ONLY example of this, that means that anything that interacts with Spider-Man and by extension the Great Weaver, has impact and meaning. Because the multiverse as a whole would be different without it. If Spider-Man say....Rallies a Group of Teenagers to stop doing drugs, there isn't a universe formed where he doesn't show up and rally them. There are some where he fails presumably, but that is a net positive for the multiverse as a whole. It solves the Problem of Meaning. And while most marvel Metahumans have interacted with Spiderman and thus the Great Weaver in some way or another even if thorough many degrees, it's perfectly plausible that other higher Dimensional Beings made it so that they are Multiversal Constants as well. Good Ol Spider-Man comics come through yet again.

This also sheds a new light of the Marvel Cosmics. See if they exist on higher branes as the Great Weaver, as they basically must for the higher-ups, then they cause the same effect:

Infinity thus imposes space as a necessity for the Multiverse, preventing universes without space from existing.
Eternity thus imposes time as a necessity for the Multiverse, preventing universes without time from existing.
Death imposes dying as a necessity for the Multiverse, preventing universes without dying from existence (save for the one obviously)
Oblivion imposes non-existence as a necessity for the Multiverse, preventing universes without the void from existence
And of course The Living Tribunal thus imposes his three concepts upon the Multiverse in the same way

The implication of these is unknown but it forces meaning to exist simply because there is not an identical amounts of potential universes, which means certain actions cause most universes of a certain type then others.

This is vaguely analogous to something DC Does. In DC the beings of the Sphere of the Gods, the Old Gods like Zeus and Odin, the New Gods like Darkseid and Highfather, and so forth are non-Quantum and exists on a higher spatial dimension brane then the Mortal Universes. As such an "aspect" of them is seen in every universe. Either an Avatar of them (the infamous Darkseid Avatars) or just their general concept appears in some form. At the top there is the 7 Endless; Destiny, Dream, Death, Destruction, Despair, Desire, and Delirium. The Endless are Wave Functions. Wave Functions are Functions in Infinite-Spatial Dimensions of a Brane Multiverse who act as ultimate Constants for every Dimension. Or at Destruction puts it so eloquently "patterns".

If I had to guess I would say that this is probably the old Marvel idea of "M-Bodies" of the Living Tribunal and the idea of Infinity being part of Multi-Infinity, Eternity being part of Multi-Eternity and so forth. These are simply the part seen from this "universe" in lower dimensional space.

*phew* Didn't expect this to be so long. I mostly meant this as a response and expansion of The Imaginary Axis' video on Multiverse Types and Marvel and DC. Hope you at least enjoyed this probably long and rambly blog.