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Why study the universe?

What's the use of studying the universe is nothing more than satisfying man's own curiosity. In fact, it is true to say that, after all, the source of science is the satisfaction of human curiosity. So today we will simply open up a brain from the perspective of curiosity: how to build a universe with existing scientific theories (regardless of technical feasibility).

Nowadays, the description of the universe is mainly based on general relativity, so can a universe be constructed through general relativity?

We know that general relativity says that "matter tells space-time how to bend, space-time tells matter how to move." in the final analysis, it is just a set of theories used to describe gravity. What constitutes the universe, in addition to the macroscopic large-scale structure, is not without the microscopic particles that make up all things in the universe.

To build everything, you have to build particles first, and quantum mechanics is necessary to build particles. Nowadays, the standard model is recognized as the most reliable theory in particle physics based on quantum mechanics. It not only describes the various fermions needed to make up matter, but also includes the various bosons that carry the interaction between them.

Is it possible to build all the elementary particles through the standard model of particle physics, thus building the whole universe?

Unfortunately, it doesn't work either.

First of all, the standard model is not perfect, and there are still many unsolved questions: for example, why do neutrinos have mass? Why are there no right-handed neutrinos? What's wrong with the mass of the Higgs particle? Wait, wait, wait...

In addition, the standard model also lacks some particles, such as gravitons and unknown dark matter particles, which can not be solved by the current standard model. All this indicates that the standard model is not the so-called "ultimate theory".

In order to construct all things in the universe, we naturally need a theory that can explain everything, that is, the "theory of everything". As one of the candidates for the theory of everything, string theory may be worth a try.

As a set of theories "discovered in advance" by human beings, string theory includes not only all the elementary particles in the standard model, but also gravitons that describe gravity. In addition, due to the introduction of one-dimensional strings, the problem of divergence of non-volumetric point particles in the standard model is avoided.

All right, now that the theoretical basis has been selected, we can begin to practice.

Because we are "building" a universe, not "creating" a universe, we do not need the "Big Bang", only a "raw energy". Note: this energy is not energy in the usual sense, but something similar to the initial conditions, similar to the "first driving force" of the universe.

Driven by the "first driving force", we use the form of "string" to construct a variety of elementary particles from the original energy, including particles in the standard model and particles that are not in the standard model. At this time, the mass source of particles no longer depends on the Higgs mechanism, but is realized by the vibration of strings.

The process is a bit like violin music: a "A major" will inspire a "upper quark", a "C minor" will stimulate an "electron", and so on.

However, according to string theory, strings can be divided into open strings and closed strings. The open string is like a piece of rope, while the closed string is like a leather band used to tie the hair, except that they are all one-dimensional structures without thickness. In fact, the elementary particles excited just now belong to the open string, but in order to build gravity, it is necessary to excite the closed string.

Since it is possible to build elementary particles through strings, it is natural to use elementary particles to build the universe. The question now is: how to build this string?

In the M theory of the King of string Theory, the solution of the supergravity equation is not an one-dimensional string, but a two-dimensional membrane. In other words, after a two-dimensional film curls a spatial dimension, it becomes an one-dimensional string previously thought.

An one-dimensional string extends between two high-dimensional films, and the mass of the particles excited by it is proportional to the distance between the two films. In other words, we can produce different elementary particles by controlling the distance between different membranes. When massless particles such as photons and gluons are needed, all you have to do is stick the two films together.

Whether they are massless or massless particles, fermions or bosons can now be constructed from strings by controlling the "membrane spacing". In this way, it is no problem to build matter and energy.

But at this point there is a bug: we find that the mass of photons constructed is not zero! To repair this bug, you need to introduce additional spatial dimensions.

In M theory, our space needs to be 10-dimensional, and there are six dimensions of finite size in addition to the three perceptible dimensions that can be extended infinitely. The space formed by these six finite dimensions is the Karabi-Qiu space.

Karabi-mound space is also called Karabi-mound manifold, which is a compact and matter-free supersymmetric space. In human words, it is a limited space in which there is a gravitational field even if there is no matter in it.

From the point of view of general relativity, the existence of a gravitational field means that there should be matter ("matter tells how space-time bends"), or at least an energy tensor. But in the Karabi-Qiu space, the space itself is curved, does not need the existence of mass matter, can be said to be born with its own gravitational field.

It seems that string theory can only be consistent in the "high-dimensional universe", so we need to build a high-dimensional space like Karabi-Qiu, and only the particles constructed through this high-dimensional space conform to the properties of particles that we are familiar with.

But the spatial dimension that we can perceive is only three-dimensional, what does the high-dimensional space look like?

Note: the high-dimensional space here is not like the "three-body" kind of "space-separated objects", let alone space-time travel (because here has been talking about the space dimension, not the time dimension). You can think of a high-dimensional space like Karabi-hill as an independent small space, as small as the Planck scale, which has nothing to do with our macroscopic three-dimensional space.

The real Karabi-mound space should be a distorted form, and there are many kinds of distorted forms in theory. Considering that we are just building a universe, we don't need to build too many forms.

Thus, through high-dimensional Karabi-mound manifolds and two-dimensional membranes, we can create a variety of elementary particles, and then through these elementary particles continue to create a variety of baryons and other composite particles, and then atoms, molecules and complex matter can also be created one after another. At this point, a "universe" that is very similar to ours has been constructed.

Oh, there seems to be one thing missing. Dark energy, but it's not a big problem. Anyway, we don't start with the Big Bang, and we don't have much time for it to evolve, so we just build a "finished" universe that doesn't accelerate expansion and is mature enough.

Although the constructed "universe" is very similar to ours, if we really have the ability to build a universe, I believe you would rather try to build a different universe. After all, "the greater the ability, the greater the curiosity", are already able to manipulate the strings, I believe it must be interesting to change the underlying parameters of the universe.

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This article comes from the official account of Wechat: Linvo says ID:linvo001, author: Linvo

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