The theory of superstrings is a popular language for dummies

The theory of superstrings, in popular language, represents the universe as a collection of vibrating strands of energy - strings. They are the basis of nature. The hypothesis describes other elements - branes. All substances in our world consist of vibrations of strings and branes. The natural consequence of the theory is the description of gravity. That's why scientists believe that it contains the key to combining gravity with other interactions.

The concept is developing

The theory of a unified field, the theory of superstrings, is purely mathematical. Like all physical concepts, it is based on equations that can be interpreted in a certain way.

Today, no one knows exactly what will be the final version of this theory. Scientists have a rather vague idea of its common elements, but no one has yet come up with a final equation that would encompass all theories of superstrings, but has not yet been experimentally confirmed (although refuted, too). Physicists have created simplified versions of the equation, but so far it does not fully describe our universe.

The theory of superstrings for beginners

Five hypotheses are based on the hypothesis.

1. The theory of superstrings predicts that all objects of our world consist of vibrating strands and energy membranes.
2. She tries to combine the general theory of relativity (gravity) with quantum physics.
3. The theory of superstrings will unite all the fundamental forces of the universe.
4. This hypothesis predicts a new connection, supersymmetry, between two fundamentally different types of particles, bosons and fermions.
5. The concept describes a number of additional, usually unobservable measurements of the universe.

Strings and Branes

When the theory originated in the 1970s, the energy threads in it were considered 1-dimensional objects - strings. The word "one-dimensional" says that a string has only 1 dimension, a length, in contrast to, for example, a square that has length and height.

These superstring theory is divided into two types - closed and open. An open string has ends that do not touch each other, while a closed string is a loop without open ends. As a result, it was found that these strings, called strings of the first type, are subject to 5 basic types of interactions.

Interactions are based on the ability of the string to connect and separate its ends. Since the ends of the open strings can unite to form closed strings, one can not construct a theory of superstrings that does not include looped strings.

This turned out to be important, since closed strings have properties, as physicists believe, which could describe gravity. In other words, scientists realized that the theory of superstrings, instead of explaining particles of matter, can describe their behavior and gravity.

After many years it was discovered that, in addition to strings, the theory needed other elements. They can be considered as sheets, or branes. Strings can be attached to one or both sides.

Quantum gravity

Modern physics has two basic scientific laws: the general theory of relativity (GTR) and the quantum theory. They represent completely different fields of science. Quantum physics studies the smallest natural particles, and GTR, as a rule, describes the nature in the scales of planets, galaxies and the universe as a whole. Hypotheses that try to unite them are called theories of quantum gravity. The most promising of them today is the string one.

Closed strands correspond to the behavior of gravity. In particular, they possess the properties of a graviton, a particle transporting gravity between objects.

Unification of forces

String theory tries to combine four forces - electromagnetic, strong and weak nuclear interactions, and gravity - into one. In our world, they manifest themselves as four different phenomena, but string theorists believe that in the early universe, when there were incredibly high energy levels, all these forces are described by strings interacting with each other.

Supersymmetry

All particles in the universe can be divided into two types: bosons and fermions. String theory predicts that there is a connection between them, called supersymmetry. For supersymmetry, for each boson there must exist a fermion and for each fermion a boson. Unfortunately, the existence of such particles has not been experimentally confirmed.

Supersymmetry is a mathematical relationship between elements of physical equations. It was discovered in another field of physics, and its application led to the renaming of the theory of supersymmetric strings (or superstring theory, popular language) in the mid-1970s.

One of the advantages of supersymmetry is that it greatly simplifies the equations, allowing you to exclude some variables. Without supersymmetry, equations lead to physical contradictions, such as infinite values and imaginary energy levels.

Since scientists did not observe the particles predicted by supersymmetry, it is still a hypothesis. Many physicists believe that the reason for this is the need for a significant amount of energy, which is related to the mass of the well-known Einstein equation E = mc ² . These particles could exist in the early universe, but as it cooled, and after the Big Bang the energy spread, these particles moved to low-energy levels.

In other words, strings vibrating as high-energy particles lost energy, which turned them into elements with lower vibration.

Scientists hope that astronomical observations or experiments with particle accelerators will confirm the theory, revealing some of the supersymmetric elements with higher energy.

Additional measurements

Another mathematical consequence of string theory is that it makes sense in a world whose number of dimensions is greater than three. Currently, there are two explanations for this:

1. Additional measurements (six of them) curled, or, in the terminology of string theory, compacted to an incredibly small size, which will never be perceived.
2. We are stuck in a 3-dimensional brane, and other dimensions extend beyond it and are inaccessible to us.

An important direction of research among theorists is mathematical modeling of how these additional coordinates can be related to ours. Recent results predict that scientists will soon be able to detect these additional dimensions (if they exist) in upcoming experiments, since they may be larger than previously expected.

Understanding the Goal

The goal to which scientists seek to investigate superstring is the "theory of everything," that is, a unified physical hypothesis that, at a fundamental level, describes the entire physical reality. If successful, she could clarify many questions about the structure of our universe.

Explanation of matter and mass

One of the main tasks of modern research is the search for solutions for real particles.

String theory began as a concept that describes such particles as hadrons, by various higher vibrational states of the string. In most modern formulations, the matter observed in our universe is the result of vibrations of strings and branes with the lowest energy. Vibrations with higher energy generate high-energy particles, which currently do not exist in our world.

The mass of these elementary particles is a manifestation of how the strings and branes are wrapped in compactified additional dimensions. For example, in the simplified case, when they are rolled up in the form of a donut, called mathematicians and physicists, the string can wrap this form in two ways:

• A short loop through the middle of the torus;
• A long loop around the entire outer circumference of the torus.

A short loop is an easy particle, and a large one is heavy. When wrapping strings around torus-shaped compactified measurements, new elements with different masses are formed.

The theory of superstrings is brief and understandable, simply and elegantly explains the transition of length to mass. Collapsed measurements are much more complicated than a torus, but in principle they also work.

Perhaps even though it is difficult to imagine that a string wraps a torus in two directions at the same time, the result will be another particle with a different mass. Branes can also wrap additional dimensions, creating even more possibilities.

Definition of space and time

In many versions, the theory of measurement superstring winds up, making them unobservable at the modern level of technology development.

At the present time it is not clear whether string theory can explain the fundamental nature of space and time more than Einstein did. In her measurements are the background for the interaction of strings and have no real meaning.

Explanations were offered that were not completely completed, concerning the representation of space-time as a derivative of the total sum of all string interactions.

This approach does not correspond to the ideas of some physicists, which led to criticism of the hypothesis. The competitive theory of loop quantum gravity as a starting point uses the quantization of space and time. Some believe that in the end it will be just another approach to the same basic hypothesis.

Quantization of gravity

The main achievement of this hypothesis, if it is confirmed, will be the quantum theory of gravity. The current description of gravity in general relativity does not agree with quantum physics. The latter, imposing restrictions on the behavior of small particles, when trying to explore the universe on an extremely small scale, leads to contradictions.

Unification of forces

At present, four fundamental forces are known to physicists: gravity, electromagnetic, weak and strong nuclear interactions. From string theory it follows that they were once all manifestations of one.

According to this hypothesis, since the early universe cooled down after the big bang, this single interaction began to disintegrate into different, acting today.

Experiments with high energies will someday allow us to discover the unification of these forces, although such experiments are far beyond the current development of technology.

Five options

After the superstring revolution of 1984, developments were conducted with feverish speed. As a result, instead of one concept, five were obtained, named type I, IIA, IIB, HO, HE, each of which almost completely described our world, but not completely.

Physicists, reviewing versions of string theory in the hope of finding a universal true formula, created 5 different self-sufficient versions. Some of their properties reflected the physical reality of the world, others did not correspond to reality.

M-theory

At a conference in 1995, physicist Edward Witten proposed a bold solution to the problem of five hypotheses. Based on the newly discovered duality, they all became special cases of a single comprehensive concept called the Witten M-theory of superstrings. One of its key concepts was branes (abbreviation from the membrane), fundamental objects possessing more than 1 dimension. Although the author did not offer the full version, which is not yet available, the M-theory of superstrings consists briefly of the following features:

• 11-dimensionality (10 spatial plus 1 time dimension);
• Duality, which lead to five theories explaining the same physical reality;
• Branes are strings, with more than 1 dimension.

Consequences

As a result, instead of one, there were ^10,500 decisions. For some physicists, this was the cause of the crisis, while others accepted the anthropic principle that explains the properties of the universe by our presence in it. It remains to be expected, when theorists will find another way of orienting in the theory of superstrings.

Some interpretations say that our world is not the only one. The most radical versions allow the existence of an infinite number of universes, some of which contain exact copies of ours.

The theory of Einstein predicts the existence of a folded space, which is called a wormhole or Einstein-Rosen bridge. In this case, the two remote areas are connected by a short passage. The theory of superstrings allows not only this, but also the connection of distant points of parallel worlds. Even a transition between universes with different laws of physics is possible. However, it is possible that the quantum theory of gravity will make their existence impossible.

Many physicists believe that the holographic principle, when all the information contained in the volume of space, corresponds to the information recorded on its surface, will allow a deeper understanding of the concept of energy threads.

Some believe that the theory of superstrings allows a multiplicity of time measurements, the consequence of which can be a journey through them.

In addition, within the hypothesis there is an alternative to the big bang model, according to which our universe appeared as a result of a collision of two branes and passes through repeated cycles of creation and destruction.

The ultimate destiny of the universe has always occupied physicists, and the final version of string theory will help determine the density of matter and the cosmological constant. Knowing these meanings, cosmologists will be able to establish whether the universe will shrink until it explodes so that everything starts again.

Nobody knows what the scientific theory can lead to until it is developed and tested. Einstein, writing the equation E = mc ² , did not expect that it would lead to the emergence of nuclear weapons. The creators of quantum physics did not know that it would become the basis for creating a laser and a transistor. And although it is not yet known what this purely theoretical concept will lead to, history shows that there will certainly be something outstanding.

More details about this hypothesis can be found in Andrew Zimmermann's book Theory of Superstrings for Dummies.