Have you ever thought that the universe is like a cello? That's right, it didn't come. Because the universe is not like a cello. But that doesn't mean she doesn't have strings. Of course, the strings of the universe are hardly similar to those that we imagine. In string theory, they are incredibly small vibrating filaments of energy. These threads are rather like tiny "elastic bands" that can wriggle, stretch and shrink in every way. All this, however, does not mean that the symphony of the Universe cannot be “played” on them, because, according to string theorists, everything that exists consists of these “threads”.

©depositphotos.com

Physics controversy

In the second half of the 19th century, it seemed to physicists that nothing serious could be discovered in their science anymore. classical physics believed that serious problems there was nothing left in it, and the whole structure of the world looked like a perfectly tuned and predictable machine. The trouble, as usual, happened because of nonsense - one of the small "clouds" that still remained in the clear, understandable sky of science. Namely, when calculating the radiation energy of a completely black body (a hypothetical body that at any temperature completely absorbs the radiation incident on it, regardless of the wavelength). Calculations showed that the total radiation energy of any absolutely black body should be infinitely large. To avoid such obvious absurdity, the German scientist Max Planck suggested in 1900 that visible light, x-rays and other electromagnetic waves can only be emitted by certain discrete portions of energy, which he called quanta. With their help, it was possible to solve the particular problem of a completely black body. However, the consequences quantum hypothesis for determinism were not yet realized. Until, in 1926, another German scientist, Werner Heisenberg, formulated the famous uncertainty principle.

Its essence boils down to the fact that, contrary to all the statements prevailing before, nature limits our ability to predict the future based on physical laws. Of course, we are talking about the future and the present. subatomic particles. It turned out that they behave completely differently than any other things in the macrocosm around us do. At the subatomic level, the fabric of space becomes uneven and chaotic. The world of tiny particles is so turbulent and incomprehensible that it contradicts common sense. Space and time are so twisted and intertwined in it that there are no ordinary concepts of left and right, up and down, and even before and after. There is no way to tell for sure at what point in space the this moment this or that particle, and what is the moment of its momentum. There is only a certain probability of finding a particle in many regions of space-time. Particles at the subatomic level seem to be "smeared" over space. Not only that, the “status” of the particles itself is not defined: in some cases they behave like waves, in others they exhibit the properties of particles. This is what physicists call wave-particle duality. quantum mechanics.

Levels of the structure of the world: 1. Macroscopic level - substance
2. Molecular level 3. Atomic level - protons, neutrons and electrons
4. Subatomic level - electron 5. Subatomic level - quarks 6. String level
©Bruno P. Ramos

In the General Theory of Relativity, as if in a state with opposite laws, things are fundamentally different. Space appears to be like a trampoline - a smooth fabric that can be bent and stretched by objects that have mass. They create deformations of space-time - what we experience as gravity. Needless to say, the coherent, correct, and predictable General Theory of Relativity is in irresolvable conflict with the "wacky hooligan" - quantum mechanics, and, as a consequence, the macrocosm cannot "reconcile" with the microcosm. This is where string theory comes in.

©John Stembridge/Atlas of Lie Groups Project

Theory of Everything

String theory embodies the dream of all physicists to unify the two, fundamentally contradictory friend of general relativity and quantum mechanics, a dream that haunted the greatest "gypsy and vagabond" Albert Einstein until the end of his days.

Many scientists believe that everything from the exquisite dance of galaxies to the frenetic dance of subatomic particles can ultimately be explained by just one fundamental physical principle. Maybe even a single law that combines all types of energy, particles and interactions in some elegant formula.

General relativity describes one of the most famous forces in the universe - gravity. Quantum mechanics describes three other forces: the strong nuclear force, which sticks protons and neutrons together in atoms, electromagnetism, and the weak force, which is involved in radioactive decay. Any event in the universe, from the ionization of an atom to the birth of a star, is described by the interactions of matter through these four forces. By using the most complex mathematics succeeded in showing that the electromagnetic and weak interactions have common nature, combining them into a single electroweak. Subsequently, the strong nuclear interaction was added to them - but gravity does not join them in any way. String theory is one of the most serious candidates for connecting all four forces, and, therefore, embracing all phenomena in the Universe - it is not without reason that it is also called the “Theory of Everything”.

©Wikimedia Commons

In the beginning there was a myth

Until now, not all physicists are enthusiastic about string theory. And at the dawn of its appearance, it did seem infinitely far from reality. Her very birth is a legend.

In the late 1960s, a young Italian theoretical physicist, Gabriele Veneziano, was looking for equations that could explain the strong nuclear forces, the extremely powerful "glue" that holds the nuclei of atoms together by binding protons and neutrons together. According to legend, he once stumbled upon a dusty book on the history of mathematics, in which he found a 200-year-old equation first written by the Swiss mathematician Leonhard Euler. Imagine Veneziano's surprise when he discovered that the Euler equation, which for a long time considered nothing more than a mathematical curiosity, describes this strong interaction.

How was it really? The equation is probably the result years work of Veneziano, and the case only helped to take the first step towards the discovery of string theory. Euler equation, miraculously explaining the strong interaction has taken on a new life.

In the end, it caught the eye of a young American theoretical physicist, Leonard Susskind, who saw that in the first place the formula described particles that did not have internal structure and could vibrate. These particles behaved in such a way that they could not just be point particles. Susskind understood - the formula describes a thread that is like an elastic band. She could not only stretch and shrink, but also oscillate, writhe. After describing his discovery, Susskind introduced the revolutionary idea of ​​strings.

Unfortunately, the overwhelming majority of his colleagues received the theory rather coolly.

standard model

At the time, mainstream science represented particles as points, not strings. For years, physicists have been investigating the behavior of subatomic particles, colliding them at high speeds and studying the consequences of these collisions. It turned out that the universe is much richer than one could imagine. It was a real population explosion» elementary particles. PhD students physical universities ran through the corridors shouting that they had opened new particle, - there were not even enough letters to designate them.

But, alas, in the "maternity hospital" of new particles, scientists could not find the answer to the question - why are there so many of them and where do they come from?

This prompted physicists to make an unusual and startling prediction - they realized that the forces acting in nature can also be explained using particles. That is, there are particles of matter, and there are particles-carriers of interactions. Such, for example, is a photon - a particle of light. The more of these particles-carriers - the same photons that are exchanged by particles of matter, the brighter light. Scientists have predicted that this particular exchange of carrier particles is nothing more than what we perceive as force. This was confirmed by experiments. So physicists managed to get closer to Einstein's dream of joining forces.

©Wikimedia Commons

Scientists believe that if we fast-forward to the moment immediately after big bang, when the universe was trillions of degrees hotter, particles that carry electromagnetism and weak interaction become indistinguishable and unite into a single force called electroweak. And if we go back in time even further, then the electroweak interaction would combine with the strong one into one total “superforce”.

Despite the fact that all this is still waiting to be proven, quantum mechanics has suddenly explained how three of the four forces interact at the subatomic level. And she explained it beautifully and consistently. This harmonious picture of interactions, in the end, was called the Standard Model. But, alas, even in this perfect theory there was one a big problem- it did not include the most known force macro level - gravity.

©Wikimedia Commons

graviton

For string theory, which did not have time to "bloom", "autumn" came, it contained too many problems from its very birth. For example, the calculations of the theory predicted the existence of particles, which, as it was soon established precisely, did not exist. This is the so-called tachyon - a particle that moves in a vacuum faster than light. Among other things, it turned out that the theory requires as many as 10 dimensions. It is not surprising that this was very embarrassing for physicists, because it is obviously more than what we see.

By 1973, only a few young physicists were still struggling with the mysteries of string theory. One of them was the American theoretical physicist John Schwartz. For four years, Schwartz tried to tame the naughty equations, but to no avail. Among other problems, one of these equations stubbornly described a mysterious particle that had no mass and was not observed in nature.

The scientist had already decided to abandon his disastrous business, and then it dawned on him - maybe the equations of string theory describe, among other things, gravity? However, this implied a revision of the dimensions of the main "heroes" of the theory - the strings. Assuming that the strings are billions and billions of times less than an atom, "stringers" turned the lack of theory into its dignity. The mysterious particle that John Schwartz had so persistently tried to get rid of now acted as a graviton - a particle that had been searched for for a long time and which would allow gravity to be transferred to the quantum level. This is how string theory has added gravity to the puzzle, which is missing from the Standard Model. But, alas, even for this discovery science community did not react at all. String theory remained on the brink of survival. But this did not stop Schwartz. Only one scientist who was willing to risk his career for the sake of mysterious strings wanted to join his search - Michael Green.

American theoretical physicist John Schwartz (top) and Michael Green
©California Institute of Technology/elementy.ru

What reason is there to think that gravity obeys the laws of quantum mechanics? For the discovery of these "grounds" in 2011 was awarded Nobel Prize in physics. It consisted in the fact that the expansion of the Universe is not slowing down, as was once thought, but, on the contrary, is accelerating. This acceleration is explained by the action of a special “anti-gravity”, which is somehow characteristic of the empty space of cosmic vacuum. On the other hand, at the quantum level, there can be nothing absolutely “empty” – subatomic particles constantly appear and immediately disappear in vacuum. Such "flickering" of particles is believed to be responsible for the existence of "anti-gravity" dark energy, which fills the empty space.

At one time, it was Albert Einstein, who until the end of his life did not accept the paradoxical principles of quantum mechanics (which he himself predicted), suggested the existence of this form of energy. Following the tradition of Aristotle's classical Greek philosophy with its belief in the eternity of the world, Einstein refused to believe what his own theory predicted, namely that the universe had a beginning. To "perpetuate" the universe, Einstein even introduced a certain cosmological constant into his theory, and thus described the energy empty space. Fortunately, a few years later it turned out that the Universe is not a frozen form at all, that it is expanding. Then Einstein abandoned the cosmological constant, calling it "the greatest miscalculation of his life."

Today, science knows that dark energy does exist, although its density is much less than that suggested by Einstein (the problem of dark energy density, by the way, is one of the greatest mysteries modern physics). But no matter how small the value of the cosmological constant, it is quite enough to make sure that quantum effects exist in gravity.

Subatomic nesting dolls

Despite everything, in the early 1980s, string theory still had unresolvable contradictions, known in science as anomalies. Schwartz and Green set about eliminating them. And their efforts were not in vain: scientists managed to eliminate some of the contradictions of the theory. Imagine the astonishment of these two, already accustomed to the fact that their theory is ignored, when the reaction of the scientific community exploded scientific world. In less than a year, the number of string theorists jumped to hundreds. It was then that string theory was awarded the title of The Theory of Everything. New theory seemed capable of describing all the components of the universe. And here are the ingredients.

Each atom, as we know, consists of even smaller particles - electrons, which circle around the nucleus, which consists of protons and neutrons. Protons and neutrons, in turn, are made up of even smaller particles called quarks. But string theory says it doesn't end with quarks. Quarks are made up of tiny snaking filaments of energy that resemble strings. Each of these strings is unimaginably small. So small that if the atom were enlarged to the size solar system, the string would be the size of a tree. Just as the different vibrations of a cello string create what we hear as different musical notes, various ways(modes) the vibrations of the string give the particles their unique properties mass, charge, etc. Do you know how, relatively speaking, the protons in the tip of your nail differ from the graviton that has not yet been discovered? Just the set of tiny strings that make them up and how those strings vibrate.

Of course, all this is more than amazing. Ever since the time Ancient Greece physicists are accustomed to the fact that everything in this world consists of something like balls, tiny particles. And now, not having time to get used to the illogical behavior of these balls, which follows from quantum mechanics, they are invited to leave the paradigm altogether and operate with some kind of spaghetti trimmings...

Fifth Dimension

Although many scientists call string theory the triumph of mathematics, some problems still remain - most notably, the lack of any opportunity to test it experimentally in the near future. Not a single instrument in the world, either existing or capable of appearing in perspective, is incapable of “seeing” the strings. Therefore, some scientists, by the way, even ask the question: is string theory a theory of physics or philosophy?.. True, it is not at all necessary to see strings “with your own eyes”. To prove string theory, rather, something else is required - something that sounds like Science fiction- confirmation of the existence of additional dimensions of space.

About what in question? We are all accustomed to three dimensions of space and one - time. But string theory predicts the presence of other - additional - dimensions. But let's start in order.

In fact, the idea of ​​the existence of other dimensions arose almost a hundred years ago. It came to the head of the then unknown German mathematician Theodor Kalutz in 1919. He suggested the possibility of the presence in our universe of another dimension that we do not see. Albert Einstein heard about this idea, and at first he liked it very much. Later, however, he doubted its correctness, and delayed Kaluza's publication by as much as two years. Ultimately, however, the article was nevertheless published, and the extra dimension became a kind of passion for the genius of physics.

As you know, Einstein showed that gravity is nothing but a deformation of space-time measurements. Kaluza suggested that electromagnetism could also be ripples. Why don't we see it? Kaluza found the answer to this question - the ripples of electromagnetism can exist in an additional, hidden dimension. But where is it?

The answer to this question was given by the Swedish physicist Oscar Klein, who suggested that the fifth dimension of Kaluza is curled up billions of times more than the size of a single atom, so we cannot see it. The idea that this tiny dimension exists all around us is at the heart of string theory.

Inside each of these forms, a string vibrates and moves - the main component of the Universe.
Each shape is six-dimensional - according to the number of six additional dimensions
©Wikimedia Commons

ten dimensions

But in fact, the equations of string theory require not even one, but six additional dimensions (in total, with four known to us, there are exactly 10 of them). All of them have a very twisted and twisted complex shape. And everything is unimaginably small.

How can these tiny dimensions affect our Big world? According to string theory, decisive: for it, everything is determined by the form. When you play different keys on the saxophone, you get and different sounds. This is because when you press a particular key or combination of keys, you change the shape of the space in the musical instrument where the air circulates. Because of this, different sounds are born.

String theory suggests that the extra twisted and twisted dimensions of space show up in a similar way. The forms of these additional dimensions are complex and varied, and each causes the string inside such dimensions to vibrate in a different way precisely because of its forms. After all, if we assume, for example, that one string vibrates inside a jug, and the other inside a curved post horn, these will be completely different vibrations. However, if string theory is to be believed, in reality, the shapes of extra dimensions look much more complicated than a jar.

How the world works

Science today knows a set of numbers that are the fundamental constants of the universe. They determine the properties and characteristics of everything around us. Among such constants, for example, the charge of an electron, the gravitational constant, the speed of light in vacuum... And if we change these numbers even by a small number of times, the consequences will be catastrophic. Suppose we increased the strength electromagnetic interaction. What happened? We can suddenly find that the ions have become stronger repel each other, and thermonuclear fusion, which makes stars shine and radiate heat, suddenly malfunctioned. All stars will go out.

But what about string theory with its extra dimensions? The fact is that, according to it, it is the additional dimensions that determine exact value fundamental constants. Some forms of measurement cause one string to vibrate in a certain way, and give rise to what we see as a photon. In other forms, the strings vibrate differently and produce an electron. Truly God lies in the "little things" - it is these tiny forms that determine all the fundamental constants of this world.

superstring theory

In the mid-1980s, string theory gained a majestic and slim look, but within this monument confusion reigned. In just a few years, as many as five versions of string theory have emerged. And although each of them is built on strings and extra dimensions (all five versions are combined into general theory superstrings), these versions diverged considerably in details.

So, in some versions, the strings had open ends, in others they looked like rings. And in some versions, the theory even required not 10, but as many as 26 measurements. The paradox is that all five versions today can be called equally true. But which one really describes our universe? it another riddle string theory. That is why many physicists again waved their hand at the "crazy" theory.

But the most the main problem strings, as already mentioned, in the impossibility (according to at least, while) to prove their presence experimentally.

Some scientists, however, still say that on the next generation of accelerators there is a very minimal, but still, opportunity to test the hypothesis of extra dimensions. Although the majority, of course, is sure that if this is possible, then, alas, it should not happen very soon - at least in decades, as a maximum - even in a hundred years.

Ultimately, all elementary particles can be represented as microscopic multidimensional strings in which vibrations of various harmonics are excited.

Attention, fasten your seat belts tighter - and I will try to describe to you one of the strangest theories from among the scientific circles seriously discussed today, which can finally give the final clue to the structure of the Universe. This theory looks so wild that, quite possibly, it is correct!

Various versions of string theory are today considered as the main contenders for the title of a comprehensive universal theory that explains the nature of everything that exists. And this is a kind of Holy Grail of theoretical physicists involved in the theory of elementary particles and cosmology. Universal Theory (aka. theory of everything) contains only a few equations that combine the totality of human knowledge about the nature of interactions and properties of the fundamental elements of matter from which the Universe is built. Today, string theory has been combined with the concept supersymmetry, resulting in the birth superstring theory, and today this is the maximum that has been achieved in terms of unifying the theory of all four main interactions (forces acting in nature). The theory of supersymmetry itself is already built on the basis of a priori modern concept, according to which any remote (field) interaction is due to the exchange of particles-carriers of interaction of the corresponding kind between the interacting particles ( cm. standard model). For clarity, the interacting particles can be considered the "bricks" of the universe, and the particles-carriers - cement.

As part of standard model quarks act as building blocks, and interaction carriers are gauge bosons, which these quarks exchange with each other. The theory of supersymmetry goes even further and claims that quarks and leptons themselves are not fundamental: they all consist of even heavier and experimentally undiscovered structures (bricks) of matter, held together by an even stronger “cement” of super-energetic particles-carriers of interactions than quarks. in hadrons and bosons. Naturally, none of the predictions of the theory of supersymmetry has yet been verified in the laboratory, but the hypothetical hidden components material world already have names, for example, seelectron(supersymmetric partner of an electron), squark etc. The existence of these particles, however, is unambiguously predicted by theories of this kind.

The picture of the universe offered by these theories, however, is quite easy to visualize. On a scale of about 10 -35 m, that is, 20 orders of magnitude smaller than the diameter of the same proton, which includes three bound quarks, the structure of matter differs from what we are used to even at the level of elementary particles. At such small distances (and at such high interaction energies that it is unthinkable) matter turns into a series of field standing waves, similar to those excited in strings musical instruments. Like a guitar string, in such a string, in addition to the fundamental tone, many overtones or harmonics. Each harmonic has its own energy state. According to principle of relativity (cm. The theory of relativity), energy and mass are equivalent, which means that the higher the frequency of the harmonic wave vibration of the string, the higher its energy, and the higher the mass of the observed particle.

However, if a standing wave in a guitar string is visualized quite simply, standing waves, offered by the theory of superstrings, are difficult to visualize - the fact is that the vibrations of superstrings occur in a space that has 11 dimensions. We are accustomed to a four-dimensional space, which contains three spatial and one temporal dimensions (left-right, up-down, forward-backward, past-future). In the space of superstrings, things are much more complicated (see inset). Theoretical physicists get around the slippery problem of "extra" spatial dimensions by arguing that they are "hidden" (or, scientific language expressed, "compactify") and therefore are not observed at ordinary energies.

More recently, string theory has received further development as theory of multidimensional membranes- in fact, these are the same strings, but flat. As one of its authors casually joked, membranes differ from strings in much the same way that noodles differ from vermicelli.

That, perhaps, is all that can be briefly told about one of the theories, not without reason claiming today to be the universal theory of the Great Unification of all force interactions. Alas, this theory is not without sin. First of all, it has not yet been brought to a strict mathematical form due to the insufficiency of the mathematical apparatus for bringing it into strict internal correspondence. It has been 20 years since this theory came into being, and no one has been able to consistently harmonize some of its aspects and versions with others. Even more unpleasant is the fact that none of the theorists who propose the theory of strings (and, especially, superstrings) has not yet proposed a single experiment on which these theories could be tested in the laboratory. Alas, I am afraid that until they do this, all their work will remain a bizarre fantasy game and an exercise in comprehending esoteric knowledge outside the mainstream of natural science.

See also:

1972	quantum chromodynamics

How many dimensions are there?

We, ordinary people, have always had enough of three dimensions. Since time immemorial we have been accustomed to describe physical world within such a modest framework (a saber-toothed tiger 40 meters in front, 11 meters to the right and 4 meters above me - a cobblestone for battle!). The theory of relativity has taught most of us that time is the essence of the fourth dimension (the saber-toothed tiger is not just here - it threatens us here and now!). And so, starting from the middle of the 20th century, theorists started talking about the fact that there are actually even more dimensions - either 10, or 11, or even 26. Of course, without explaining why we, normal people, we do not observe them, it could not do here. And then the concept of "compactification" arose - the adhesion or collapse of dimensions.

Imagine a garden watering hose. Up close, it is perceived as a normal three-dimensional object. It is necessary, however, to move away from the hose at a sufficient distance - and it will appear to us as a one-dimensional linear object: we simply cease to perceive its thickness. It is this effect that is commonly referred to as the compactification of a dimension: this case The thickness of the hose turned out to be “compacted” - the scale of the measurement scale is too small.

This is exactly how, according to the theorists, the really existing additional dimensions disappear from the field of our experimental perception, which are necessary for an adequate explanation of the properties of matter at the subatomic level: they become compact, starting from a scale of about 10 -35 m, modern methods observation and measuring instruments simply unable to detect structures on such a small scale. Perhaps this is exactly how it is, or perhaps things are completely different. While there are no such devices and methods of observation, all the above arguments and counter-arguments will remain at the level of idle speculation.

Of course, the strings of the universe are hardly similar to those that we imagine. In string theory, they are incredibly small vibrating filaments of energy. These threads are rather like tiny "elastic bands" that can wriggle, stretch and shrink in every way. All this, however, does not mean that the symphony of the Universe cannot be “played” on them, because, according to string theorists, everything that exists consists of these “threads”.

Physics controversy

In the second half of the 19th century, it seemed to physicists that nothing serious could be discovered in their science anymore. Classical physics believed that there were no serious problems left in it, and the whole structure of the world looked like a perfectly tuned and predictable machine. The trouble, as usual, happened because of nonsense - one of the small "clouds" that still remained in the clear, understandable sky of science. Namely, when calculating the radiation energy of a completely black body (a hypothetical body that at any temperature completely absorbs the radiation incident on it, regardless of the wavelength - NS).

Calculations showed that the total radiation energy of any absolutely black body should be infinitely large. To avoid such obvious absurdity, the German scientist Max Planck suggested in 1900 that visible light, X-rays, and other electromagnetic waves could only be emitted by certain discrete portions of energy, which he called quanta. With their help, it was possible to solve the particular problem of a completely black body. However, the consequences of the quantum hypothesis for determinism were not yet realized at that time. Until, in 1926, another German scientist, Werner Heisenberg, formulated the famous uncertainty principle.

Its essence boils down to the fact that, contrary to all the statements prevailing before, nature limits our ability to predict the future on the basis of physical laws. This, of course, is about the future and present of subatomic particles. It turned out that they behave completely differently than any other things in the macrocosm around us do. At the subatomic level, the fabric of space becomes uneven and chaotic. The world of tiny particles is so turbulent and incomprehensible that it is contrary to common sense. Space and time are so twisted and intertwined in it that there are no ordinary concepts of left and right, up and down, and even before and after.

There is no way to say for sure at which particular point in space this or that particle is located at a given moment, and what is the moment of its momentum. There is only a certain probability of finding a particle in many regions of space-time. Particles at the subatomic level seem to be "smeared" over space. Not only that, the “status” of the particles itself is not defined: in some cases they behave like waves, in others they exhibit the properties of particles. This is what physicists call the wave-particle duality of quantum mechanics.

World structure levels: 1. Macroscopic level - matter 2. Molecular level 3. Atomic level - protons, neutrons and electrons 4. Subatomic level - electron 5. Subatomic level - quarks 6. String level /©Bruno P. Ramos

In the General Theory of Relativity, as if in a state with opposite laws, things are fundamentally different. Space appears to be like a trampoline - a smooth fabric that can be bent and stretched by objects that have mass. They create deformations of space-time - what we experience as gravity. Needless to say, the coherent, correct and predictable General Theory of Relativity is in an insoluble conflict with the "wacky hooligan" - quantum mechanics, and, as a result, the macrocosm cannot "reconcile" with the microcosm. This is where string theory comes in.

2D Universe. E8 polyhedron graph /©John Stembridge/Atlas of Lie Groups Project

Theory of Everything

String theory embodies the dream of all physicists to unite two fundamentally contradictory general relativity and quantum mechanics, a dream that haunted the greatest "gypsy and vagabond" Albert Einstein until the end of his days.

Many scientists believe that everything from the exquisite dance of galaxies to the frenzied dance of subatomic particles can ultimately be explained by just one fundamental physical principle. Maybe even a single law that combines all types of energy, particles and interactions in some elegant formula.

General relativity describes one of the most famous forces in the universe - gravity. Quantum mechanics describes three other forces: the strong nuclear force, which sticks protons and neutrons together in atoms, electromagnetism, and the weak force, which is involved in radioactive decay. Any event in the universe, from the ionization of an atom to the birth of a star, is described by the interactions of matter through these four forces.

With the help of complex mathematics, it was possible to show that the electromagnetic and weak interactions have a common nature, combining them into a single electroweak one. Subsequently, the strong nuclear interaction was added to them - but gravity does not join them in any way. String theory is one of the most serious candidates for connecting all four forces, and, therefore, embracing all phenomena in the Universe - it is not without reason that it is also called the “Theory of Everything”.

In the beginning there was a myth

Until now, not all physicists are enthusiastic about string theory. And at the dawn of its appearance, it did seem infinitely far from reality. Her very birth is a legend.

In the late 1960s, a young Italian theoretical physicist, Gabriele Veneziano, was looking for equations that could explain the strong nuclear forces, the extremely powerful "glue" that holds the nuclei of atoms together by binding protons and neutrons together. According to legend, he once stumbled upon a dusty book on the history of mathematics, in which he found a 200-year-old function, first recorded by the Swiss mathematician Leonhard Euler. Imagine Veneziano's surprise when he discovered that the Euler function, which for a long time was considered nothing more than a mathematical curiosity, describes this strong interaction.

How was it really? The formula was probably the result of Veneziano's long years of work, and the case only helped to take the first step towards the discovery of string theory. The Euler function, which miraculously explained the strong force, has found a new life.

Eventually, it caught the eye of a young American theoretical physicist, Leonard Susskind, who saw that the formula primarily described particles that had no internal structure and could vibrate. These particles behaved in such a way that they could not just be point particles. Susskind understood - the formula describes a thread that is like an elastic band. She could not only stretch and shrink, but also oscillate, writhe. After describing his discovery, Susskind introduced the revolutionary idea of ​​strings.

Unfortunately, the overwhelming majority of his colleagues received the theory rather coolly.

standard model

At the time, mainstream science represented particles as points, not strings. For years, physicists have been investigating the behavior of subatomic particles, colliding them at high speeds and studying the consequences of these collisions. It turned out that the universe is much richer than one could imagine. It was a real "population explosion" of elementary particles. Graduate students of physics universities ran through the corridors shouting that they had discovered a new particle - there were not even enough letters to designate them. But, alas, in the "maternity hospital" of new particles, scientists could not find the answer to the question - why are there so many of them and where do they come from?

This prompted physicists to make an unusual and startling prediction - they realized that the forces acting in nature can also be explained using particles. That is, there are particles of matter, and there are particles-carriers of interactions. Such, for example, is a photon - a particle of light. The more of these carrier particles - the same photons that matter particles exchange, the brighter the light. Scientists have predicted that this particular exchange of carrier particles is nothing more than what we perceive as force. This was confirmed by experiments. So physicists managed to get closer to Einstein's dream of joining forces.

Interactions between different particles in the Standard Model /

Scientists believe that if we fast-forward to just after the Big Bang, when the universe was trillions of degrees hotter, the particles that carry electromagnetism and the weak force would become indistinguishable and coalesce into a single force called the electroweak. And if we go back in time even further, then the electroweak interaction would combine with the strong one into one total “superforce”.

Despite the fact that all this is still waiting to be proven, quantum mechanics has suddenly explained how three of the four forces interact at the subatomic level. And she explained it beautifully and consistently. This harmonious picture of interactions, in the end, was called the Standard Model. But, alas, even in this perfect theory there was one big problem - it did not include the most famous force of the macro level - gravity.

graviton

For string theory, which did not have time to "bloom", "autumn" came, it contained too many problems from its very birth. For example, the calculations of the theory predicted the existence of particles, which, as it was soon established precisely, did not exist. This is the so-called tachyon - a particle that moves faster than light in vacuum. Among other things, it turned out that the theory requires as many as 10 dimensions. It is not surprising that this was very embarrassing for physicists, because it is obviously more than what we see.

By 1973, only a few young physicists were still struggling with the mysteries of string theory. One of them was the American theoretical physicist John Schwartz. For four years, Schwartz tried to tame the naughty equations, but to no avail. Among other problems, one of these equations stubbornly described a mysterious particle that had no mass and was not observed in nature.

The scientist had already decided to abandon his disastrous business, and then it dawned on him - maybe the equations of string theory describe, among other things, gravity? However, this implied a revision of the dimensions of the main "heroes" of the theory - the strings. By assuming that strings are billions and billions of times smaller than an atom, the "stringers" turned the flaw of the theory into its virtue. The mysterious particle that John Schwartz had so persistently tried to get rid of now acted as a graviton - a particle that had been searched for for a long time and which would allow gravity to be transferred to the quantum level. This is how string theory has added gravity to the puzzle, which is missing from the Standard Model. But, alas, even the scientific community did not react to this discovery. String theory remained on the brink of survival. But this did not stop Schwartz. Only one scientist who was willing to risk his career for the sake of mysterious strings wanted to join his search - Michael Green.

Subatomic nesting dolls

In spite of everything, in the early 1980s, string theory still had unresolvable contradictions, known in science as anomalies. Schwartz and Green set about eliminating them. And their efforts were not in vain: scientists managed to eliminate some of the contradictions of the theory. Imagine the amazement of these two, already accustomed to the fact that their theory is ignored, when the reaction of the scientific community blew up the scientific world. In less than a year, the number of string theorists jumped to hundreds. It was then that string theory was awarded the title of The Theory of Everything. The new theory seemed capable of describing all the components of the universe. And here are the ingredients.

Each atom, as we know, consists of even smaller particles - electrons, which circle around the nucleus, which consists of protons and neutrons. Protons and neutrons, in turn, are made up of even smaller particles called quarks. But string theory says it doesn't end with quarks. Quarks are made up of tiny snaking filaments of energy that resemble strings. Each of these strings is unimaginably small.

So small that if the atom were enlarged to the size of the solar system, the string would be the size of a tree. Just as the different vibrations of a cello string create what we hear, as different musical notes, the different ways (modes) of vibrating a string give particles their unique properties—mass, charge, and so on. Do you know how, relatively speaking, the protons in the tip of your nail differ from the graviton that has not yet been discovered? Just the set of tiny strings that make them up and how those strings vibrate.

Of course, all this is more than amazing. Ever since the days of ancient Greece, physicists have become accustomed to the fact that everything in this world consists of something like balls, tiny particles. And now, not having time to get used to the illogical behavior of these balls, which follows from quantum mechanics, they are invited to leave the paradigm altogether and operate with some kind of spaghetti trimmings...

Fifth Dimension

Although many scientists call string theory the triumph of mathematics, some problems still remain - most notably, the lack of any opportunity to test it experimentally in the near future. Not a single instrument in the world, either existing or capable of appearing in perspective, is incapable of “seeing” the strings. Therefore, some scientists, by the way, even ask the question: is string theory a theory of physics or philosophy?.. True, it is not at all necessary to see strings “with your own eyes”. What is required to prove string theory is rather something else—what sounds like science fiction—confirmation of the existence of extra dimensions of space.

What is this about? We are all accustomed to three dimensions of space and one - time. But string theory predicts the presence of other - additional - dimensions. But let's start in order.

In fact, the idea of ​​the existence of other dimensions arose almost a hundred years ago. It came to the head of the then unknown German mathematician Theodor Kalutz in 1919. He suggested the possibility of the presence in our universe of another dimension that we do not see. Albert Einstein heard about this idea, and at first he liked it very much. Later, however, he doubted its correctness, and delayed Kaluza's publication by as much as two years. Ultimately, however, the article was nevertheless published, and the extra dimension became a kind of passion for the genius of physics.

As you know, Einstein showed that gravity is nothing but a deformation of space-time measurements. Kaluza suggested that electromagnetism could also be ripples. Why don't we see it? Kaluza found the answer to this question - the ripples of electromagnetism can exist in an additional, hidden dimension. But where is it?

The answer to this question was given by the Swedish physicist Oscar Klein, who suggested that the fifth dimension of Kaluza is curled up billions of times more than the size of a single atom, so we cannot see it. The idea that this tiny dimension exists all around us is at the heart of string theory.

One of the proposed forms of extra swirling dimensions. Inside each of these forms, a string vibrates and moves - the main component of the Universe. Each form is six-dimensional - according to the number of six additional dimensions /

ten dimensions

But in fact, the equations of string theory require not even one, but six additional dimensions (in total, with four known to us, there are exactly 10 of them). All of them have a very twisted and twisted complex shape. And everything is unimaginably small.

How can these tiny dimensions affect our big world? According to string theory, decisive: for it, everything is determined by the form. When you play different keys on the saxophone, you get different sounds. This is because when you press a particular key or combination of keys, you change the shape of the space in the musical instrument where the air circulates. Because of this, different sounds are born.

String theory suggests that the extra twisted and twisted dimensions of space show up in a similar way. The forms of these additional dimensions are complex and varied, and each causes the string inside such dimensions to vibrate in a different way precisely because of its forms. After all, if we assume, for example, that one string vibrates inside a jug, and the other inside a curved post horn, these will be completely different vibrations. However, if string theory is to be believed, in reality, the shapes of extra dimensions look much more complicated than a jar.

How the world works

Science today knows a set of numbers that are the fundamental constants of the universe. They determine the properties and characteristics of everything around us. Among such constants, for example, the charge of an electron, the gravitational constant, the speed of light in vacuum... And if we change these numbers even by a small number of times, the consequences will be catastrophic. Suppose we have increased the strength of the electromagnetic interaction. What happened? We may suddenly find that the ions have become more repulsive from each other, and thermonuclear fusion, which makes stars shine and radiate heat, has suddenly failed. All stars will go out.

But what about string theory with its extra dimensions? The fact is that, according to it, it is the extra dimensions that determine the exact value of the fundamental constants. Some forms of measurement cause one string to vibrate in a certain way, and give rise to what we see as a photon. In other forms, the strings vibrate differently and produce an electron. Truly God lies in the "little things" - it is these tiny forms that determine all the fundamental constants of this world.

superstring theory

In the mid-1980s, string theory took on a majestic and slender air, but within that monument, confusion reigned. In just a few years, as many as five versions of string theory have emerged. And although each of them is built on strings and extra dimensions (all five versions are united in the general theory of superstrings - NS), in details these versions diverged significantly.

So, in some versions, the strings had open ends, in others they looked like rings. And in some versions, the theory even required not 10, but as many as 26 measurements. The paradox is that all five versions today can be called equally true. But which one really describes our universe? This is another mystery of string theory. That is why many physicists again waved their hand at the "crazy" theory.

But the main problem of strings, as already mentioned, is the impossibility (at least for now) to prove their presence experimentally.

Some scientists, however, still say that on the next generation of accelerators there is a very minimal, but still, opportunity to test the hypothesis of extra dimensions. Although the majority, of course, is sure that if this is possible, then, alas, it should not happen very soon - at least in decades, as a maximum - even in a hundred years.

Various versions of string theory are now considered as the main contenders for the title of a comprehensive universal theory that explains the nature of everything that exists. And this is a kind of Holy Grail of theoretical physicists involved in the theory of elementary particles and cosmology. The universal theory (aka the theory of everything) contains only a few equations that combine the totality of human knowledge about the nature of interactions and properties of the fundamental elements of matter from which the Universe is built.

Today, string theory has been combined with the concept of supersymmetry, resulting in the birth of superstring theory, and today this is the maximum that has been achieved in terms of unifying the theory of all four main interactions (forces acting in nature). The theory of supersymmetry itself has already been built on the basis of an a priori modern concept, according to which any remote (field) interaction is due to the exchange of particles-carriers of an interaction of the appropriate kind between interacting particles (see the Standard Model). For clarity, interacting particles can be considered the "bricks" of the universe, and carrier particles - cement.

String theory - direction mathematical physics, which studies the dynamics of not point particles, like most branches of physics, but one-dimensional extended objects, i.e. strings.
Within the framework of the Standard Model, quarks act as building blocks, and gauge bosons, which these quarks exchange with each other, act as interaction carriers. The theory of supersymmetry goes even further and states that the quarks and leptons themselves are not fundamental: they all consist of even heavier and experimentally undiscovered structures (bricks) of matter, held together by an even stronger “cement” of super-energy particles-carriers of interactions than quarks. in hadrons and bosons.

Naturally, in laboratory conditions, none of the predictions of the theory of supersymmetry has yet been verified, however, the hypothetical hidden components of the material world already have names - for example, the electron (the supersymmetric partner of the electron), the squark, etc. The existence of these particles, however, theories of such kind is unambiguously predicted.

The picture of the universe offered by these theories, however, is quite easy to visualize. On scales of the order of 10E–35 m, that is, 20 orders of magnitude smaller than the diameter of the same proton, which includes three bound quarks, the structure of matter differs from what we are accustomed to even at the level of elementary particles. At such small distances (and at such high interaction energies that it is unthinkable), matter turns into a series of field standing waves, similar to those that are excited in the strings of musical instruments. Like a guitar string, in addition to the fundamental tone, many overtones or harmonics can be excited in such a string. Each harmonic has its own energy state. According to the principle of relativity (see Theory of Relativity), energy and mass are equivalent, which means that the higher the frequency of the harmonic wave vibration of a string, the higher its energy, and the higher the mass of the observed particle.

However, if a standing wave in a guitar string is visualized quite simply, the standing waves proposed by superstring theory are difficult to visualize - the fact is that superstrings vibrate in a space that has 11 dimensions. We are accustomed to a four-dimensional space, which contains three spatial and one temporal dimensions (left-right, up-down, forward-backward, past-future). In the space of superstrings, things are much more complicated (see inset). Theoretical physicists get around the slippery problem of "extra" spatial dimensions by arguing that they are "hidden" (or, in scientific terms, "compactified") and therefore are not observed at ordinary energies.

More recently, string theory has been further developed in the form of the theory of multidimensional membranes - in fact, these are the same strings, but flat. As one of its authors casually joked, membranes differ from strings in much the same way that noodles differ from vermicelli.

That, perhaps, is all that can be briefly told about one of the theories, not without reason claiming today to be the universal theory of the Great Unification of all force interactions. Alas, this theory is not without sin. First of all, it has not yet been brought to a rigorous mathematical form due to the insufficiency of the mathematical apparatus for bringing it into strict internal correspondence. It has been 20 years since this theory came into being, and no one has been able to consistently harmonize some of its aspects and versions with others. Even more unpleasant is the fact that none of the theorists who propose the theory of strings (and, especially, superstrings) has not yet proposed a single experiment on which these theories could be tested in the laboratory. Alas, I am afraid that until they do this, all their work will remain a bizarre fantasy game and an exercise in comprehending esoteric knowledge outside the mainstream of natural science.

Studying the properties of black holes

In 1996, string theorists Andrew Strominger and Cumrun Wafa, relying on more early results Susskind and Sen, published "The Microscopic Nature of Bekenstein and Hawking's Entropy". In this work, Strominger and Wafa were able to use string theory to find the microscopic components of a certain class of black holes, as well as to accurately calculate the contributions of these components to entropy. The work was based on the application of a new method, partly beyond the scope of perturbation theory, which was used in the 1980s and early 1990s. The result of the work exactly coincided with the predictions of Bekenstein and Hawking, made more than twenty years earlier.

Strominger and Vafa opposed the real processes of formation of black holes constructive approach. They changed the view of black hole formation by showing that they can be constructed by painstakingly assembling into one mechanism the exact set of branes discovered during the second superstring revolution.

Having in hand all the controls of a microscopic design black hole, Strominger and Vafa were able to calculate the number of permutations of a black hole's microscopic components that leave common observable characteristics, such as mass and charge, unchanged. After that, they compared the resulting number with the area of ​​the black hole's event horizon - the entropy predicted by Bekenstein and Hawking - and found perfect agreement. At least for the class of extremal black holes, Strominger and Vafa were able to find an application of string theory to analyze microscopic components and calculate the corresponding entropy exactly. The problem that had confronted physicists for a quarter of a century was solved.

For many theorists, this discovery was important and convincing argument in support of string theory. The development of string theory is still too crude for a direct and accurate comparison with experimental results, for example, with the results of measurements of the masses of a quark or an electron. String theory, however, provides the first fundamental justification long ago. public property black holes, the impossibility of explaining which for many years hampered the research of physicists working with traditional theories. Even Sheldon Glashow Nobel Laureate in physics and a staunch opponent of string theory in the 1980s, admitted in an interview in 1997 that "when string theorists talk about black holes, they are talking almost about observable phenomena, and this is impressive."

String cosmology

There are three main points at which string theory modifies the standard cosmological model. First, in the spirit contemporary research, increasingly clarifying the situation, it follows from string theory that the Universe should have a minimum allowable size. This conclusion changes the idea of ​​the structure of the Universe immediately at the moment of the Big Bang, for which the standard model gives the zero size of the Universe. Secondly, the notion of T-duality, that is, the duality of small and large radii(in his close connection with the existence of a minimum size) in string theory is also important in cosmology. Thirdly, the number of space-time dimensions in string theory is more than four, so cosmology must describe the evolution of all these dimensions.

Model of Brandenberg and Wafa

In the late 1980s Robert Brandenberger and Kumrun Wafa made the first important steps to understanding what changes in the consequences of the standard cosmological model will use string theory. They came to two important findings. First, as we move back to the time of the Big Bang, the temperature continues to rise until the moment when the size of the universe in all directions equals the Planck length. At this point, the temperature will reach a maximum and begin to decrease. On an intuitive level, it is not difficult to understand the reason for this phenomenon. Assume for simplicity (following Brandenberger and Wafa) that all spatial dimensions of the universe are cyclic. As we move backwards in time, the radius of each circle shrinks and the temperature of the universe increases. We know from string theory that reducing the radii first to and then below the Planck length is physically equivalent to decreasing the radii to the Planck length, followed by their subsequent increase. Since the temperature drops during the expansion of the Universe, then unsuccessful attempts to compress the Universe to sizes smaller than the Planck length will lead to the cessation of temperature growth and its further decrease.

As a result, Brandenberger and Vafa arrived at the following cosmological picture: first, all spatial dimensions in string theory are tightly coiled up to a minimum dimension of the order of the Planck length. Temperature and energy are high, but not infinite: the paradoxes of the size zero starting point in string theory are solved. AT initial moment the existence of the Universe, all the spatial dimensions of string theory are completely equal and completely symmetrical: they are all rolled up into a multidimensional lump of Planck dimensions. Further, according to Brandenberger and Wafa, the Universe goes through the first stage of symmetry reduction, when at the Planck time three spatial dimensions are selected for subsequent expansion, while the rest retain their original Planck size. These three dimensions are then identified with the dimensions in the scenario inflationary cosmology and in the process of evolution take the now observable form.

Model Veneziano and Gasperini

Since the work of Brandenberger and Wafa, physicists have made continuous progress toward understanding string cosmology. Among those who lead these studies are Gabriele Veneziano and his colleague Maurizio Gasperini from the University of Turin. These scientists presented their version of string cosmology, which in a number of places is in contact with the scenario described above, but in other places is fundamentally different from it. Like Brandenberger and Wafa, in order to exclude the infinite temperature and energy density that arise in the standard and inflationary model, they relied on the existence of a minimum length in string theory. However, instead of concluding that, due to this property, the universe is born from a lump of Planck size, Gasperini and Veneziano suggested that there was a prehistoric universe that arose long before the moment called zero point, and gave birth to this cosmic “embryo” of Planck dimensions.

The initial state of the Universe in such a scenario and in the Big Bang model is very different. According to Gasperini and Veneziano, the Universe was not a hot and tightly twisted ball of dimensions, but was cold and had an infinite extent. Then, as follows from the equations of string theory, instability invaded the Universe, and all its points began, as in the era of inflation according to Guth, to rapidly scatter to the sides.

Gasperini and Veneziano showed that because of this, space became more and more curved and as a result there was a sharp jump in temperature and energy density. A little time passed, and a three-dimensional millimeter-sized area inside these endless expanses transformed into a red-hot and dense spot, identical to the spot that is formed during inflationary expansion according to Guth. Then everything went according to the standard scenario of Big Bang cosmology, and the expanding spot became the observable Universe.

Because the pre-Big Bang era saw its own inflationary expansion, Guth's solution to the horizon paradox is automatically built into this cosmological scenario. In the words of Veneziano (in a 1998 interview), "string theory presents us with a variant of inflationary cosmology on a silver platter."

The study of string cosmology is rapidly becoming an area of ​​active and productive research. For example, the scenario of evolution before the Big Bang has been the subject of heated debate more than once, and its place in the future cosmological formulation is far from obvious. However, there is no doubt that this cosmological formulation will be firmly based on the understanding by physicists of the results discovered during the second superstring revolution. For example, the cosmological consequences of the existence of multidimensional membranes are still not clear. In other words, how will the idea of ​​the first moments of the existence of the Universe change as a result of the analysis of the completed M-theory? This issue is being intensively researched.

Science is a vast field and great amount research and discoveries are carried out daily, while it is worth noting that some theories seem to be interesting, but at the same time they do not have real evidence and, as it were, “hang in the air”.

What is string theory?

The physical theory that represents particles in the form of vibration is called string theory. These waves have only one parameter - longitude, and the height and width are missing. In figuring out that this is string theory, you should consider the main hypotheses that it describes.

1. It is assumed that everything around is made up of filaments that vibrate and membranes of energy.
2. Tries to combine general relativity and quantum physics.
3. String theory offers a chance to unite everything fundamental forces Universe.
4. Predicts a symmetrical relationship between different types particles: bosons and fermions.
5. Gives a chance to describe and present dimensions of the Universe that have not been observed before.

String theory - who discovered it?

1. First time in 1960 quantum theory strings was created to explain the phenomenon in hadron physics. At that time, it was developed by G. Veneziano, L. Susskind, T. Goto and others.
2. He told what string theory is, the scientist D. Schwartz, J. Sherk and T. Yene, since they developed the hypothesis of bosonic strings, and this happened 10 years later.
3. In 1980, two scientists: M. Green and D. Schwartz identified the theory of superstrings, which had unique symmetries.
4. Studies of the proposed hypothesis are being carried out to this day, but it has not yet been proven.

String Theory - Philosophy

There is a philosophical direction that has a connection with string theory, and they call it a monad. It involves the use of symbols in order to compactify any amount of information. Monad and string theory in philosophy use opposites and dualities. The most popular simple monad symbol is Yin-Yang. Experts suggested that string theory be depicted on a three-dimensional rather than on a flat monad, and then the strings will be a reality, even though they are long and scanty.

If a volumetric monad is used, then the line dividing Yin-Yang will be a plane, and using a multidimensional monad, a spiralized volume is obtained. While there is no work in philosophy concerning multidimensional monads - this is an area for study in the future. Philosophers believe that cognition is an endless process and when trying to create a single model of the universe, a person will be surprised more than once and change his basic concepts.

Drawbacks of String Theory

Since the hypothesis proposed by a number of scientists is unconfirmed, it is quite understandable that there are a number of problems that indicate the need for its refinement.

1. Has string theory misconceptions, for example, when calculating it was discovered new type particles are tachyons, but they cannot exist in nature, since the square of their mass less than zero, and the speed of movement more speed Sveta.
2. String theory can only exist in a ten-dimensional space, but then the question is relevant - why does a person not perceive other dimensions?

String theory - proof

The two main physical conventions on which the scientific evidence, in fact, oppose each other, since they represent the structure of the universe at the micro level in different ways. To try them on, a theory was proposed cosmic strings. In many respects, it looks reliable, and not only in words, but also in mathematical calculations, but today a person does not have the opportunity to practically prove it. If strings exist, they are at the microscopic level, and there are no technical possibilities yet to recognize them.

String Theory and God

The famous theoretical physicist M. Kaku proposed a theory in which he proves the existence of the Lord with the help of the string hypothesis. He came to the conclusion that everything in the world operates according to certain laws and rules established by a single Mind. According to Kaku, string theory and hidden dimensions The Universe will be helped to create an equation that unites all the forces of nature and allows you to understand the mind of God. He emphasizes his hypothesis on tachyon particles, which move faster than light. Even Einstein said that if you find such parts, it will be possible to move time back.

After conducting a series of experiments, Kaku concluded that human life is governed by stable laws, and does not respond to cosmic accidents. String theory in life exists, and it is associated with an unknown force that controls life and makes it whole. In his opinion, this is what it is. Kaku is sure that the universe is vibrating strings that come from the mind of the Supreme.