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# Multiverse

*For more in-depth explanations of the Multiverse check this video and this article regarding the four different levels.*

## Introduction

A **Multiverse** is a hypothetical set of possible alternate universes that together can comprise anything from a comparatively simple collection of parallel 4-dimensional universal space-time continuums, to a higher dimensional multiversal structure in our reality due to some theories, or sometimes even higher levels of reality.

This includes the entirety of space and time within a certain continuum, as well as the physical laws and constants that describe them.

There is a great distinction between characters that can merely destroy or create simple collections of universes, and ones that can destroy or create more complex higher-hierarchal structures. To understand more about this, please read the Tiering System.

## Omniverse

The definition of **Omniverse** essentially refers to everything in a verse's cosmology. Due to there being no set nature and the word being rarely used, omniverse has no real relevance.

## Higher Dimensional Theories

In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interact with each other. On distance scales larger than the string scale, a string looks just like an ordinary particle, with its mass, charge, and other properties determined by the vibrational state of the string. In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries gravitational force. Thus string theory is a theory of quantum gravity.

In everyday life, there are three familiar dimensions (3D) of space: height, width and length. Einstein's general theory of relativity treats time as a dimension on par with the three spatial dimensions; in general relativity, space and time are not modeled as separate entities but are instead unified to a four-dimensional (4D) spacetime. In this framework, the phenomenon of gravity is viewed as a consequence of the geometry of spacetime.

In spite of the fact that the Universe is well described by 4D spacetime, there are several reasons why physicists consider theories in other dimensions. In some cases, by modeling spacetime in a different number of dimensions, a theory becomes more mathematically tractable, and one can perform calculations and gain general insights more easily. There are also situations where theories in two or three spacetime dimensions are useful for describing phenomena in condensed matter physics. Finally, there exist scenarios in which there could actually be more than 4D of spacetime which have nonetheless managed to escape detection.

One notable feature of string theories is that these theories require extra dimensions of spacetime for their mathematical consistency. In bosonic string theory, spacetime is 26-dimensional, while in superstring theory it is 10-dimensional, and in M-theory it is 11-dimensional. In order to describe real physical phenomena using string theory, one must therefore imagine scenarios in which these extra dimensions would not be observed in experiments.

To have more understanding of this, read here. Along with reading here regarding our page on dimensionality. It should also be noted that a higher dimensional multiverse does not increase one's attack potency it merely just gives a multiverse more dimensional axis.

## Max Tegmark's Multiverse

Comes from here. Cosmologist Max Tegmark has provided a taxonomy of universes beyond the familiar observable universe. The four levels of Tegmark's classification are arranged such that subsequent levels can be understood to encompass and expand upon previous levels. They are briefly described below.

**Level I: An extension of our universe**
A prediction of cosmic inflation is the existence of an infinite ergodic universe, which, being infinite, must contain Hubble volumes realizing all initial conditions.

Accordingly, an infinite universe will contain an infinite number of Hubble volumes, all having the same physical laws and physical constants. In regard to configurations such as the distribution of matter, almost all will differ from our Hubble volume. However, because there are infinitely many, far beyond the cosmological horizon, there will eventually be Hubble volumes with similar, and even identical, configurations. Tegmark estimates that an identical volume to ours should be about 10^10^115 meters away from us.

Given infinite space, there would, in fact, be an infinite number of Hubble volumes identical to ours in the universe. This follows directly from the cosmological principle, wherein it is assumed that our Hubble volume is not special or unique.

Under our wiki's tiering, this would be a **2-C** cosmology.

**Level II: Universes with different physical constants**
In the eternal inflation theory, which is a variant of the cosmic inflation theory, the multiverse or space as a whole is stretching and will continue doing so forever, but some regions of space stop stretching and form distinct bubbles (like gas pockets in a loaf of rising bread). Such bubbles are embryonic level I multiverses.

Different bubbles may experience different spontaneous symmetry breaking, which results in different properties, such as different physical constants.

Level II also includes John Archibald Wheeler's oscillatory universe theory and Lee Smolin's fecund universes theory.

Under our wiki's tiering, this would be a **Low 2-B** to **High 2-B** cosmology on a case by case basis.

**Level III: Many-worlds interpretation of quantum mechanics**
Hugh Everett III's many-worlds interpretation (MWI) is one of several mainstream interpretations of quantum mechanics.

In brief, one aspect of quantum mechanics is that certain observations cannot be predicted absolutely. Instead, there is a range of possible observations, each with a different probability. According to the MWI, each of these possible observations corresponds to a different universe. Suppose a six-sided die is thrown and that the result of the throw corresponds to quantum mechanics observable. All six possible ways the dice can fall correspond to six different universes.

Tegmark argues that a Level III multiverse does not contain more possibilities in the Hubble volume than a Level I or Level II multiverse. In effect, all the different "worlds" created by "splits" in a Level III multiverse with the same physical constants can be found in some Hubble volume in a Level I multiverse. Tegmark writes that, "The only difference between Level I and Level III is where your doppelgängers reside. In Level I they live elsewhere in good old three-dimensional space. In Level III they live on another quantum branch in infinite-dimensional Hilbert space."

Similarly, all Level II bubble universes with different physical constants can, in effect, be found as "worlds" created by "splits" at the moment of spontaneous symmetry breaking in a Level III multiverse. According to Yasunori Nomura, Raphael Bousso, and Leonard Susskind, this is because global spacetime appearing in the (eternally) inflating multiverse is a redundant concept. This implies that the multiverses of Levels I, II, and III are, in fact, the same thing. This hypothesis is referred to as "Multiverse = Quantum Many Worlds". According to Yasunori Nomura, this quantum multiverse is static, and time is a simple illusion.

For more information regarding this one should read here.

Under our wiki's tiering, this would be a **2-B** to **High 2-B** cosmology on a case by case basis.

**Level IV: Ultimate ensemble**
The ultimate mathematical universe hypothesis is Tegmark's own hypothesis.

This level considers all universes to be equally real which can be described by different mathematical structures.

Tegmark writes:
*Abstract mathematics is so general that any Theory Of Everything (TOE) which is definable in purely formal terms (independent of vague human terminology) is also a mathematical structure. For instance, a TOE involving a set of different types of entities (denoted by words, say) and relations between them (denoted by additional words) is nothing but what mathematicians call a set-theoretical model, and one can generally find a formal system that it is a model of.*

He argues that this "implies that any conceivable parallel universe theory can be described at Level IV" and "subsumes all other ensembles, therefore brings closure to the hierarchy of multiverses, and there cannot be, say, a Level V."

Jürgen Schmidhuber, however, says that the set of mathematical structures is not even well-defined and that it admits only universe representations describable by constructive mathematics—that is, computer programs.

Schmidhuber explicitly includes universe representations describable by non-halting programs whose output bits converge after finite time, although the convergence time itself may not be predictable by a halting program, due to the undecidability of the halting problem. He also explicitly discusses the more restricted ensemble of quickly computable universes.

As a Level IV multiverse is one in which mathematics is everything, all possible mathematical structures that can be described exist at some level, which would include any possible level of reality that can be conceived of using set theory. As a result of this, the Level IV multiverse is the highest, most complex multiversal system that can be conceived of, and as such, it qualifies for **1-A** on our system. Do note that due to the incomprehensible complexity of this level and its resulting tier, verses that make mention of a Level IV multiverse for their cosmology must be handled with immense scrutiny, and their portrayal of it must be blatant and consistent enough to be rewarded the tier, otherwise it will be given a much lower tier.

**Disclaimer:** Normally if an entire multiverse is pure data and information with mathematical structures, it's enough to be accepted as a level IV multiverse, however do note this is in a reality where **all** of reality is this, if it's based off a data world/video game universe and there exists a real world then it's not a level IV multiverse as the real world isn't comprised of data and thus not every mathematical structure exists.

## Theory of Everything

The Theory of Everything is an overarching hypothetical framework that would explain the physics of the entire universe in a single equation. But unifying theories that define the large-scale cosmological structure of the universe with those that describe the minuscule quantum world of the subatomic particles has been a challenge for over a century. There are some verses that follow this underlying ideal though theory of everythings do not have a set size and widely vary.

**Singular Universe:**There are theories for the theory of everything that only concern themself with how space-time is shaped and thus have no bearing on if a multiverse exist or not, in cases like this if the verse in question is noted to follow a theory of everything but does not showcase a multiverse, the minimum assumption will be a**2-C**cosmology.

**Multiverse:**Any verse that has a multiverse with a theory of everything would fall at the very least at a**2-A**cosmology, as by this point this would fall under the idea of the many worlds interpretation.

**Composite Panethons:**Composite Panethons are in a more religious and philosophical realm rather then scientific, though it is pretty easy to gauge that if in a composite pantheon, every creation story is equally true, then this would also essentially be the equivalent to a theory of everything. These depend on the verse and normally would be in the multiverse range, though some can be in the singular universe range too.

**Ultimate Theory of Everything:**So far the only widely recognized ultimate theory of everything is the mathematical universal hypothesis, explained above under the level IV multiverse section. Nothing can truly be great then it and thus it is the highest apex, for theory of everything in a similar qualifier, this would reach a**1-A**cosmology.

## Other Mathematical Related Models

### Platonism

The Mathematical Universe Hypothesis seems to gain some inspiration from Platonism, which in this philosophy it was believed that mathematics is an abstract formula existing within the world of forms, unlike the MUH though, in Platonism this means that reality itself is not made of math, though rather in the world of forms, all mathematical possibilities exist, this would make reality itself whatever tier the cosmology decides to give and the world of forms **1-A**. For learning how to apply this, please read the **Further 1-A Explanations section of the tiering system**.

### Pythagoreanism

Platonism seemingly draws some inspiration from Pythagoreanism's philosophy of the *mathēmatikoi*, where in this belief, numbers are the heart of everything and are what constructed the cosmos. In this case this one is similar to the MUH in that reality itself is formed from the numbers, though it doesn't seem to be directly made of math, regardless as all mathematical equations essentially are formed in this reality, it would overall be **1-A**. For learning how to apply this, please read the **Further 1-A Explanations section of the tiering system**.