What are fundamental interactions? Four physical forces Weak nuclear forces.

What powers do you know? gravity, thread tension, compression of a spring, collision of bodies, force of friction, explosion, air and medium resistance, surface tension of a liquid, van der Waals forces - and the list does not end there. But all these forces are derivatives of the four fundamental ones! They will be discussed.

four forces

The basis of the foundations of physical laws are four fundamental interactions, which are responsible for all processes in the universe. If elementary particles can be compared with the bricks of being, then interactions are a cement mortar. Strong, electromagnetic, weak and gravitational - in this order, from strong to weak, interactions are considered. They cannot be reduced to simpler ones - that is why they are called fundamental.

Before proceeding to the description of forces, it is necessary to explain what is meant by the word interaction. Physicists consider it as the result of an exchange of certain intermediaries, they are usually called carriers of interaction.

Let's start with the most intense. strong interaction was discovered in the 30s of the last century during the period of active research of the atom. It turned out that the integrity and stability of its core is precisely ensured by an extremely strong interaction nucleons between themselves.

Nucleons(from lat. nucleus - nucleus) - the general name for protons and neutrons, the main components of the atom's nucleus. From the point of view of the strong interaction, these particles are indistinguishable. The neutron is heavier than the proton by 0.13% - this turned out to be enough to become the only elementary particle with a rest mass for which a gravitational interaction was observed.

The contents of the nuclei are attracted to each other due to special quanta - π-mesons, which are the "official" carriers of the strong interaction. Such a nuclear force is 1038 times more intense than the weakest interaction - gravitational. If the strong force suddenly disappeared, the atoms in the universe would instantly disintegrate. Behind them, molecules, then matter - all the reality surrounding us would cease to exist, with the exception of elementary particles. An interesting feature of their "relationships" is the short-range action: positively charged particles, protons, are attracted to each other only when they are in direct contact.

If the protons are some distance apart, then electromagnetic an interaction in which like-charged particles repel, and oppositely charged particles attract. In the case of uncharged particles, this force does not arise - let us recall the famous Coulomb's law on immobile point electric charges. The carriers of electromagnetic forces are photons, which provide, among other things, the transfer of the energy of the Sun to our planet. The exclusion of this force threatens the Earth with complete freezing. The electromagnetic interaction is 1035 times stronger than the gravitational one, that is, only 100 times weaker than the nuclear one.

Nature has provided another fundamental force, characterized by a vanishingly low intensity and a very small radius of action (less than an atomic nucleus). This weak interaction - its carriers are special charged and neutral bosons. The sphere of responsibility of the weak forces is primarily the beta decay of the neutron, accompanied by the formation of a proton, an electron, and an (anti-)neutrino. Such transformations are actively taking place on the Sun, which determines the importance of this fundamental interaction for us.

(Un)explored gravity

All the described forces have been studied in sufficient detail and organically built into the physical picture of the world. However, the last power gravitational, is distinguished by such a low intensity that one still has to guess about its essence.

The paradox of the gravitational interaction is that we feel it every second, but we cannot fix the carrier in any way. There is only an assumption about the existence of a hypothetical graviton quantum with the speed of light. It is capable of interference and diffraction, but is deprived of charge. Scientists believe that when one particle emits a graviton, the nature of its movement changes, a similar situation develops with a particle that receives a quantum. The level of development of technology does not yet allow us to "see" the graviton and study its properties in more detail. The intensity of gravity is 1025 times less than the weak interaction.

How come, you say, the force of gravity does not seem weak at all! This is the unique properties of the fundamental interaction No. 4. For example, universality - any body with any mass creates a gravitational field in space that can penetrate any obstacle. Moreover, the force of gravity increases with the mass of the object - a property that is characteristic only for this interaction.

That is why the Earth, gigantic in comparison with a man, creates a gravitational field around itself, which keeps air, water, rocks and, of course, a living shell on the surface. If gravity is canceled at once, the speed with which you and I will go into space will be 500 m / s. Along with the electromagnetic interaction, gravity has a long range. Therefore, its role in the system of moving bodies in the Universe is enormous. Even between two people who are at a considerable distance from each other, there is a microscopic gravitational attraction.

The Gravity Gun is a fictional weapon that creates a local gravity field. The weapon allows you to pull, lift and throw objects due to the force generated by the field. This concept was first used in the computer game Half-life 2.

Imagine a spinning top, vertically fixed in the center of an annular frame, freely rotating around a horizontal axis. This frame - let's call it internal - is, in turn, fixed on an external annular frame, which also freely rotates in a horizontal plane. The design around the top is called gimbals, and all together it gyroscope.

At rest, the top in the gyroscope peacefully rotates in a vertical position, but as soon as external forces - for example, acceleration - try to turn the top's axis of rotation, it turns perpendicular to this effect. No matter how hard we try to turn the top in the gyroscope, it will still rotate in a vertical position. The most advanced gyroscopes react even to the rotation of the Earth, which was first demonstrated by the Frenchman Jean Bernard Foucault in 1851. If we equip a gyroscope with a sensor that reads the position of the top relative to the frame, we will get an accurate navigation device that allows us to track the movement of an object in space - for example, an airplane.

Gravitational effects

Gravity can play a cruel trick on large, much more massive objects in space, much more massive than the Earth, such as stars in the later stages of evolution. The force of attraction compresses the star and at a certain moment overpowers the internal pressure. When the radius of such an object becomes less than the gravitational one, collapse and the star goes out. No more information comes from it, even light rays cannot overcome the gigantic force of attraction. This is how a black hole is born.

Planets, objects much more miniature, have their own gravitational features. So, the Earth, due to its own mass, bends space-time and twists it with its rotation! These phenomena are called geodesic precession and gravitomagnetic effect, respectively.

What is geodesic precession? Imagine that an object moves along the orbit of our planet, on the surface of which (in weightlessness) a top rotates at high speed. Its axis will deviate in the direction of motion with an intensity of 6.6 arc seconds per year. The Earth bends the surrounding space-time with its mass, creating a kind of recess in it.

Gravitomagnetic effect(Lense-Thirring effect) illustrates well the rotation of a stick in thick honey: it carries along a viscous sweet mass, forming a spiral swirl. So the Earth, by rotation, spins the "honey" space-time around its axis. And this is fixed again by the axis of the top, which deviates towards the Earth's rotation by a microscopic 0.04 arc seconds per year.

Our planet with its gravity affects time and space. This statement for a long time remained only a hypothesis of Einstein and his followers, until in 2004 the Americans launched the Gravity Probe-B satellite. The device rotated in the polar orbit of the Earth and was equipped with the most accurate gyroscopes in the world - complicated analogs of tops. The complexity of these technical masterpieces is evidenced by the fact that the irregularities on the gyroscope balls did not exceed two or three atoms. If these miniature spheres are enlarged to the size of the Earth, then the height of the largest irregularity will not exceed three meters! Such tricks were needed to experimentally establish the very curvature of space-time. And after 17 months of work in orbit, the equipment recorded the displacement of the rotation axes of four supergyroscopes at once!

During the Gravity Probe-B experiment, two effects of the General Theory of Relativity were proved: the curvature of space-time (geodesic precession) and the appearance of additional acceleration near massive bodies (gravitomagnetic effect)

Gravity has a lot of other, much more obvious effects. For example, in our body there is not a single organ that has not been adapted to earth's gravity.

That is why it is so unusual and even dangerous for a person to be in a state of weightlessness for a long time: the blood is redistributed throughout the body in such a way that it exerts excessive pressure on the vessels of the brain, and the bones eventually refuse to absorb calcium salts and become brittle, like a reed. Only by constant physical activity can a person partially protect himself from the consequences of weightlessness.

The gravitational field of the Moon affects the Earth and its inhabitants - everyone knows about the ebb and flow of tides. Due to the centrifugal force, the Moon is moving away from us by 4 cm per year, and the intensity of the tides is inexorably decreasing. In the prehistoric period, the Moon was much closer to the Earth, and, accordingly, the tides were significant. Perhaps this was the main factor that predetermined the emergence of living organisms on land.

Even though we still don't know which particle is responsible for gravity, we can measure it! For this, a special device is used - gravimeter, with which geologists actively work in search of minerals.

In the thickness of the earth's surface, rocks have different densities, and, consequently, their gravitational force will vary. This way you can determine the deposits of light hydrocarbons (oil and gas), as well as dense rocks of metal ores. They measure the force of attraction, fixing the slightest change in the speed of free fall of a body with a known mass or the stroke of a pendulum. For this, they even introduced a special unit of measurement - Gal (Gal) in honor of Galileo Galilei, who was the first in history to determine the force of gravity by measuring the path of a freely falling body.

Long-term studies of the Earth's gravity from space have made it possible to create a map of the gravitational anomalies of our planet. A sharp increase in the force of gravity on a separate piece of land can be a harbinger of an earthquake or volcanic eruption.

The study of fundamental interactions is only gaining momentum. It cannot be said with certainty that there are only four forces - there may be five or ten. Scientists are trying to collect all the interactions under the "roof" of one model, but it is still oh so far before its creation. And the hypothetical graviton becomes the main center of gravity. Skeptics say that a person will never be able to fix this quantum, since its intensity is too low, but optimists believe in the future of technologies and methods of physics. Wait and see.

Force- a vector physical quantity, which is a measure of the intensity of the impact on a given body of other bodies, as well as fields. The force applied to a massive body is the cause of a change in its speed or the occurrence of deformations in it.

In modern science, 4 types of interactions are distinguished. Two of them, which are considered in mechanics, are called gravitational And electromagnetic. They correspond to forces that cannot be reduced to simpler ones, and therefore they are called fundamental. Two more: strong and weak are nuclear. Force of attraction and g. Deformation - this is a change in the size or shape of a body under the influence of other bodies. As is known from the course of school physics, all bodies are made up of electric charges. When bodies are deformed, the distances between charges change, and this, in turn, leads to an imbalance between the forces of attraction and repulsion between charges. When a body is stretched, attractive forces between charges predominate and the body "resists" stretching; similarly, when compressed, repulsive forces predominate. Hooke's law. Support reaction force and suspension tension force. IN body weight called the force with which the body acts on the support or suspension. When a body interacts with a support or suspension, the body itself is deformed, which leads to the appearance of an elastic force acting on the support or suspension. The forces of weight and the support reaction are interconnected according to Newton's third law. A similar equality exists for a body on a suspension. T=R. Friction force.

Within the framework of classical mechanics, the gravitational interaction is described by Newton's law of universal gravitation, which states that the force of gravitational attraction between two material points of mass and , separated by a distance, is proportional to both masses and inversely proportional to the square of the distance - that is:

Electromagnetic interaction exists between particles that have an electric charge. From the modern point of view, the electromagnetic interaction between charged particles is not carried out directly, but only through the electromagnetic field.

The strong interaction involves quarks and gluons and particles composed of them, called hadrons (baryons and mesons). It operates on scales of the order of the size of the atomic nucleus or less, being responsible for the connection between quarks in hadrons and for the attraction between nucleons (a kind of baryons - protons and neutrons) in nuclei.

Weak interaction, or weak nuclear force- one of the four fundamental interactions in nature. It is responsible, in particular, for the beta decay nucleus. This interaction is called weak, since the other two interactions that are significant for nuclear physics (strong and electromagnetic) are characterized by a much greater intensity. However, it is much stronger than the fourth of the fundamental interactions, gravitational. Weak interaction is short-range - it manifests itself at distances much smaller than the size of the atomic nucleus.

There are four types of forces in nature: gravitational, electromagnetic, nuclear and weak.

gravitational forces, or gravitational force, operate between all bodies. But these forces are noticeable if at least one of the bodies has dimensions commensurate with the dimensions of the planets. The forces of attraction between ordinary bodies are so small that they can be neglected. Therefore, gravitational forces can be considered the forces of interaction between the planets, as well as between the planets and the Sun or other bodies that have a very large mass. These can be stars, satellites of planets, etc.

Electromagnetic forces act between bodies that have an electric charge.

nuclear forces(strong) are the most powerful in nature. They act inside the nuclei of atoms at distances of 10 -13 cm.

Weak Forces, like nuclear ones, act at small distances of the order of 10 -15 cm. As a result of their action, processes occur inside the nucleus.

Mechanics considers gravitational forces, elastic forces and frictional forces.

Gravitational forces

Gravity is described the law of universal gravitation. This law was outlined by Newton in the middle XVII V. in Mathematical Principles of Natural Philosophy.

Gravitycalled the gravitational force with which any material particles are attracted to each other.

The force with which material particles are attracted to each other is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. .

G - gravitational constant, numerically equal to the modulus of the gravitational force with which a body having a unit mass acts on a body having the same unit mass and located at a unit distance from it.

G \u003d 6.67384 (80) 10 −11 m 3 s −2 kg −1, or N m² kg −2.

On the surface of the Earth, the gravitational force (gravitational force) manifests itself in the form gravity.

We see that any object thrown in a horizontal direction still falls down. Any object thrown up also falls down. This is due to the force of gravity acting on any material body located near the surface of the Earth. Gravity acts on bodies and on the surfaces of other astronomical bodies. This force is always directed vertically downwards.

Under the influence of gravity, the body moves to the surface of the planet with an acceleration called free fall acceleration.

The free fall acceleration on the Earth's surface is denoted by the letter g .

F t = mg ,

hence,

g = F t / m

g \u003d 9.81 m / s 2 at the poles of the Earth, and at the equator g \u003d 9.78 m / s 2.

When solving simple physical problems, the quantity g it is considered to be equal to 9.8 m / s 2.

The classical theory of gravitation is applicable only for bodies with a speed much lower than the speed of light.

elastic forces

Forces of elasticity called the forces that arise in the body as a result of deformation, causing a change in its shape or volume. These forces always strive to return the body to its original position.

During deformation, the particles of the body are displaced. The elastic force is directed in the direction opposite to the direction of particle displacement. If the deformation stops, the elastic force disappears.

The English physicist Robert Hooke, a contemporary of Newton, discovered a law establishing a relationship between the force of elasticity and the deformation of a body.

When the body is deformed, an elastic force arises, which is directly proportional to the elongation of the body, and has a direction opposite to the movement of particles during deformation.

F = k ∆ l ,

Where To is the rigidity of the body, or coefficient of elasticity;

∆ l - the amount of deformation, showing the amount of elongation of the body under the influence of elastic forces.

Hooke's law is valid for elastic deformations when the elongation of the body is small, and the body restores its original dimensions after the forces that caused this deformation disappear.

If the deformation is large and the body does not return to its original shape, Hooke's law does not apply. At very large deformations, the destruction of the body occurs.

Friction forces

Friction occurs when one body moves over the surface of another. It has an electromagnetic nature. This is a consequence of the interaction between atoms and molecules of adjoining bodies. The direction of the friction force is opposite to the direction of motion.

Distinguish dry And liquid friction. Friction is called dry if there is no liquid or gaseous layer between the bodies.

A distinctive feature of dry friction is static friction, which occurs when bodies are at relative rest.

Value static friction force always equal to the magnitude of the external force and directed in the opposite direction. The static friction force prevents the body from moving.

In turn, dry friction is divided into friction slip and friction rolling.

If the magnitude of the external force exceeds the magnitude of the friction force, then in this case slippage will appear, and one of the contacting bodies will begin to move forward relative to the other body. And the force of friction will be called sliding friction force. Its direction will be opposite to the direction of sliding.

The sliding friction force depends on the force with which the bodies press on each other, on the state of the rubbing surfaces, on the speed of movement, but does not depend on the contact area.

The sliding friction force of one body on the surface of another is calculated by the formula:

F tr. = k N ,

Where k- coefficient of sliding friction;

N is the normal reaction force acting on the body from the surface.

Rolling friction force occurs between a body that rolls over a surface and the surface itself. Such forces appear, for example, when the tires of a car come into contact with the road surface.

The value of the rolling friction force is calculated by the formula

Where F t – rolling friction force;

f is the coefficient of rolling friction;

R is the radius of the rolling body;

N - pressing force.

Formation of protogalactic clouds less than about 1 billion years after the Big Bang

We are well aware of the force of gravity that keeps us on the ground and makes it difficult to fly to the moon. And electromagnetism, thanks to which we do not fall apart into individual atoms and can plug laptops into the outlet. The physicist talks about two more forces that make the Universe exactly the way it is.

From the school bench, we all know the law of universal gravitation and Coulomb's law well. The first one explains how massive objects like stars and planets interact (attract) with each other. The other one shows (recall the experience with an ebonite stick) what forces of attraction and repulsion arise between electrically charged objects.

But is this the whole set of forces and interactions that determine the appearance of the Universe we observe?

Modern physics says that there are four types of basic (fundamental) interactions between particles in the Universe. I have already mentioned two of them above, and it would seem that everything is simple with them, because their manifestations constantly surround us in everyday life: this is gravitational and electromagnetic interaction.

So, due to the action of the first, we firmly stand on the ground and do not fly away into outer space. The second, for example, ensures the attraction of an electron to a proton in atoms, of which we all consist, and, ultimately, the attraction of atoms to each other (i.e., it is responsible for the formation of molecules, biological tissues, etc.). So it is precisely because of the forces of electromagnetic interaction, for example, that it turns out that it is not so easy to cut off the head of an annoying neighbor, and for this purpose we have to resort to the help of an ax of various improvised means.

But there is also the so-called strong interaction. What is it responsible for? Were you surprised in school by the fact that, despite the assertion of Coulomb's law that two positive charges must repel each other (only opposite charges attract), the nuclei of many atoms quietly exist for themselves. But they consist, as you remember, of protons and neutrons. Neutrons are neutrons because they are neutral and have no electric charge, but protons are positively charged. And what kind of forces, one wonders, can hold together (at a distance of one trillionth of a micron - which is a thousand times less than the atom itself!) Several protons, which, according to Coulomb's law, must repel each other with terrible energy?

Strong interaction - provides attraction between particles in the nucleus; electrostatic - repulsion

This truly titanic task of overcoming the Coulomb forces is taken over by the strong interaction. So, neither more nor less, due to it, protons (as, indeed, neutrons) in the nucleus are still attracted to each other. By the way, the protons and neutrons themselves also consist of even more "elementary" particles - quarks. So quarks also interact and are attracted to each other "strongly". But, fortunately, unlike the same gravitational interaction, which also works at cosmic distances of many billions of kilometers, the strong interaction is, as they say, short-range. This means that the "strong attraction" field surrounding one proton works only on tiny scales, comparable, in fact, with the size of the nucleus.

Therefore, for example, a proton sitting in the nucleus of one of the atoms cannot, having given a damn about the Coulomb repulsion, take and “strongly” attract a proton from a neighboring atom to itself. Otherwise, all proton and neutron matter in the Universe could be "attracted" to the common center of mass and form one huge "supernucleus". Something similar, however, occurs in the thickness of neutron stars, into one of which, as you can expect, one day (in about five billion years) our Sun will shrink.

So, the fourth and last of the fundamental interactions in nature is the so-called weak interaction. It is not for nothing that it is so named: not only does it work even at distances even shorter than the strong interaction, but also its power is very small. So, unlike its strong "brother", the Coulomb repulsion, it will not overtighten in any way.

A striking example demonstrating the weakness of weak interactions are particles called neutrinos (can be translated as "small neutron", "neutron"). These particles, by their nature, do not participate in strong interactions, do not have an electric charge (and therefore are not susceptible to electromagnetic interactions), have an insignificant mass even by the standards of the microworld and, therefore, are practically insensitive to gravity, in fact, are capable of only weak interactions.

What? Neutrinos pass through me?!

At the same time, neutrinos are generated in the Universe in truly colossal quantities, and a huge stream of these particles constantly penetrates the thickness of the Earth. For example, in the volume of a matchbox, on average, there are 20 neutrinos at each moment of time. Thus, one can imagine a huge barrel of water-detector, which I wrote about in my last post, and the incredible amount of neutrinos that flies through it at any given time. So, scientists working on this detector usually have to wait for months for such a happy occasion, so that at least one neutrino “feels” their barrel and interacts in it with its weak forces.

However, even despite its weakness, this interaction plays a very important role in the Universe and in human life. So, it is precisely this that is responsible for one of the types of radioactivity - namely, beta decay, which is the second (after gamma radioactivity) in terms of the degree of danger of its effect on living organisms. And, no less important, without weak interaction, it would be impossible for thermonuclear reactions to take place in the interiors of many stars and are responsible for the release of energy from the star.

This is the four horsemen of the Apocalypse of fundamental interactions that rule the Universe: strong, electromagnetic, weak and gravitational.

What are the fundamental forces of nature? On what principle are fundamental interactions built? Is the existence of a new fundamental interaction possible? Doctor of Physical and Mathematical Sciences Dmitry Kazakov answers these and other questions.

From school physics, we are faced with the concept of "force". Forces are different: there is an attractive force, a friction force, a rolling force, an elastic force. There are many different powers. Not all of these forces are fundamental - very often the force is a secondary phenomenon. For example, the force of friction is a secondary phenomenon - in fact, it is the interaction of molecules. And even the interaction of molecules can be secondary. For example, in molecular physics there are van der Waals forces. These forces are a secondary consequence of electromagnetic interactions.

I would like to get to the bottom of the most fundamental force: what are the fundamental forces in nature, which determine everything, from which all secondary forces are built? Electromagnetic forces, or electrical forces, are the fundamental forces as we understand them today. Coulomb's law, known since school physics, is a fundamental law, but it has its own generalization, it follows from Maxwell's equations. Maxwell's equations describe in general all electric and magnetic forces in nature, therefore electromagnetic interactions are the fundamental forces of nature.

Another example of the fundamental forces of nature is gravity. From school, Newton's law of universal gravitation is known, which has now been generalized in Einstein's equations - now we have Einstein's theory of gravitation. The force of gravity is also a fundamental interaction in nature. And it once seemed that only these two fundamental forces existed. But later they realized that this was not the case. In particular, when the atomic nucleus was discovered and the problem arose to understand why the particles are kept inside the nucleus and do not fly apart, the concept of nuclear forces was introduced. These nuclear forces have been measured, understood, described. But later it turned out that they are also non-fundamental - nuclear forces in a sense resemble Van der Waals forces.

The truly fundamental forces that ensure the strong interaction are the forces between quarks. interact with each other, and as a secondary effect, the protons and neutrons in the nucleus interact with each other. The fundamental interaction is the interaction of quarks through the exchange of gluons - this is the third fundamental force in nature.

But the story doesn't end there either. It turns out that the decays of elementary particles - and all heavy particles decay into lighter ones - are described by a new interaction, which is called the weak interaction. Weak - because the strength of this interaction is noticeably weaker than electromagnetic forces. But it turned out that the theory of weak interaction, which originally existed and described all decays very well, did not work well with increasing energy, and it was replaced by a new theory of weak interaction, which turned out to be completely universal and built on the same principle on which all the others are built. interactions.

There are four fundamental interactions in the modern world, and I will also talk about the fifth one.

Four fundamental interactions - electromagnetic, strong, weak and gravitational - are built on the same principle.

This principle is that the force between particles arises due to the exchange of some mediator, the carrier of interaction.

Electromagnetic interaction is based on the exchange of a quantum of light or a quantum of electromagnetic waves - this is a photon. A photon is a massless particle, charged particles exchange it, and due to this exchange, interactions between particles arise, a force between particles, Coulomb's law is also described in this way.

The other interaction is strong. There is also an intermediary, a particle exchanged between quarks. These particles are called gluons, there are eight of them, these are also massless particles.

The third particle, the third interaction, is the weak interaction, and here, too, particles, which are called intermediate vector bosons, act as an intermediary. These particles - their pieces - are massive, that is, quite heavy. This mass, the gravity of these particles, explains why the weak interaction is so weak.

The fourth interaction is gravitational, and it is carried out by exchanging a quantum of the gravitational field, it is called. The graviton has not yet been experimentally discovered, we still do not quite feel and do not quite know how to describe.

All interactions are an act of exchanging some particles. Here we return to . Any interaction is associated with symmetry. Symmetry tells how many such particles and what their mass is. If the symmetry is exact, the mass is zero. A photon has a mass of 0, a gluon has a mass of 0. If the symmetry is broken, the mass is non-zero. Intermediate vector bosons have a non-zero mass, the symmetry is broken there. The gravitational symmetry is not broken - the graviton also has a mass of 0.

These four fundamental interactions explain everything we see. All other forces are a secondary effect of these interactions. But in 2012, a new particle was discovered that became very famous - this is the so-called . The Higgs boson is also the carrier of interaction between quarks and between leptons. Therefore, now it is appropriate to say that a fifth force has appeared, the carrier of which is the Higgs boson. Here, too, the symmetry is broken - the Higgs boson is a massive particle. Thus, the number of fundamental interactions - in particle physics the word is usually used not "force", but "interaction" - has reached five.

Are there new interactions? We don't really know. In elementary particle physics there are no other interactions, there are only five. But it is possible that the model that we are now considering and perfectly describes all the experimental data and all the phenomena that we observe in the world may still be incomplete, and then, perhaps, some new forces and new interactions will appear. For example, if there are so-called , that is, if there is a new symmetry in nature, then this new symmetry will entail the emergence of new particles that are mediators between other particles, thereby creating a new fundamental force. Therefore, this possibility still remains.

Interestingly, any new interaction always leads to some new phenomenon. Say, if there were no weak interaction, there would be no decay. If there were no decay, we would not observe nuclear reactions. If there were no nuclear reactions, the Sun would not shine. If the Sun did not shine, life could not exist on Earth. So having that interaction turned out to be vital for us.

If there were no strong interaction, there would be no stable atomic nuclei. If there were no nuclei, there would be no atoms. If there were no atoms, there would be no us. That is, it turned out that all the forces seem to be necessary. Here is the electromagnetic interaction: we receive energy from the Sun - these are the rays of light that come to us from the Sun. Without him, the Earth would be cold. It turns out that all those interactions that we know are needed for something. Higgs interaction with the Higgs boson. Fundamental particles gain mass by interacting with the Higgs field - one cannot live without this either. I'm not talking about gravitational interaction - we would fly away from the surface of the planet.

All the interactions that are in nature that are now open are vital for everything that we understand and know to exist.

And what would happen if there were some new interaction that has not yet been discovered? Here is another example: the proton in the nucleus is stable, and it is very important that it is stable, otherwise, again, there would be no life. But experimentally, the proton lifetime is now limited - 1034 years. This means that there is no prohibition for the proton to decay, but this requires a new force and a new interaction. There are theories that predict the decay of the proton - they have a higher symmetry group, and they have new interactions that we do not know. Whether so it is a question to experiment.

All fundamental interactions are now built on a single principle, and in this sense there is a unity of nature. Sometimes the question arises: is it possible to explain in some way how many interactions there are in nature, that is, to understand the reason why there are four of them or why there are five of them, and maybe there are still more? There are different versions of how one could explain the presence of a certain number of fundamental interactions. Such theories are often referred to as Grand Unification theories. These theories combine various types of interactions into one. It is like a growing tree: there is a single trunk, then it branches, and various branches are obtained.

The idea is about the same: there is a single root of all interactions, a single trunk, and then, as a result of symmetry breaking, this trunk begins to branch, and several fundamental interactions are formed, which we experimentally observe. Testing this hypothesis requires physics at very high energies, which are inaccessible to modern experiment and probably never will be. But you can get around this problem. In the end, we have a natural accelerator - this is the Universe. Some processes going on in the Universe allow us to test bold hypotheses that there is a single root of all interactions.

Another very interesting challenge in understanding the interactions in nature is to understand how gravity relates to all other interactions. Gravity stands somewhat apart, although the principle of constructing the theory is very similar. At one time, Einstein tried to build a unified theory of gravity and electromagnetism. Then it seemed very real, but the theory never happened. Now we know a little more. We know that there is still a strong interaction, a weak interaction, therefore, if we are now building a unified theory, it would seem that we need to include all these interactions together, but nevertheless, such a unified theory has not yet been created, and so far we have not been able to unify gravity with the rest of the interactions. All interactions, except for gravity, obey the laws of quantum physics - this is quantum theory. All particles are quanta of a certain field. Quantum gravity does not yet exist until it can be created. What is the reason for what we do wrong, what we do not understand - all this remains a mystery. But the number of fundamental interactions that have already been discovered suggests that some kind of unified scheme probably exists.