Four types of fundamental interactions.

Fundamental Interactions

In nature, there is a huge variety of natural systems and structures, the features and development of which are explained by the interaction of material objects, that is, mutual action on each other. Exactly interaction is the main reason for the movement of matter and it is characteristic of all material objects, regardless of their origin and their systemic organization. Interaction is universal, as is movement. Interacting objects exchange energy and momentum (these are the main characteristics of their movement). In classical physics, interaction is determined by the force with which one material object acts on another. For a long time the paradigm was the concept of long-range action - the interaction of material objects located at a great distance from each other and it is transmitted through empty space instantly. Currently, another has been experimentally confirmed - concept of short-range interaction - interaction is transmitted using physical fields with a finite speed not exceeding the speed of light in a vacuum. Physical field – special kind matter that ensures the interaction of material objects and their systems (the following fields: electromagnetic, gravitational, field of nuclear forces - weak and strong). The source of the physical field is elementary particles (electromagnetic - charged particles), in quantum theory the interaction is caused by the exchange of field quanta between particles.

There are four fundamental interactions in nature: strong, electromagnetic, weak and gravitational, which determine the structure of the surrounding world.

Strong interaction(nuclear interaction) – mutual attraction components atomic nuclei (protons and neutrons) and acts at a distance of the order of 10 -1 3 cm, transmitted by gluons. From the point of view of electromagnetic interaction, a proton and a neutron are different particles, since a proton is electrically charged, and a neutron is not. But from the point of view of strong interaction, these particles are indistinguishable, since in a stable state the neutron is an unstable particle and decays into a proton, electron and neutrino, but within the nucleus it becomes similar in its properties to a proton, which is why the term “nucleon ( from lat. nucleus- nucleus)” and a proton with a neutron began to be considered as two different states of the nucleon. The stronger the interaction of nucleons in the nucleus, the more stable the nucleus, the greater the specific binding energy.

In a stable substance, the interaction between protons and neutrons at not too high temperatures increases, but if a collision of nuclei or their parts (high-energy nucleons) occurs, then nuclear reactions occur, which are accompanied by the release of enormous energy.

Under certain conditions, strong interaction very firmly binds particles into atomic nuclei - material systems with high binding energy. It is for this reason that the nuclei of atoms are very stable and difficult to destroy.

Without strong interactions, atomic nuclei would not exist, and stars and the Sun would not be able to generate heat and light using nuclear energy.

Electromagnetic interaction transmitted using electric and magnetic fields. An electric field arises in the presence of electric charges, and a magnetic field arises when they move. Changing electric field generates an alternating magnetic field - this is the source of the alternating magnetic field. This type of interaction is characteristic of electrically charged particles. The carrier of electromagnetic interaction is a photon that has no charge - a quantum of the electromagnetic field. In the process of electromagnetic interaction, electrons and atomic nuclei combine into atoms, and atoms into molecules. In a certain sense, this interaction is fundamental in chemistry and biology.

We receive about 90% of information about the world around us through an electromagnetic wave, since various states of matter, friction, elasticity, etc. are determined by the forces of intermolecular interaction, which are electromagnetic in nature. Electromagnetic interactions are described by the laws of Coulomb, Ampere and Maxwell's electromagnetic theory.

Electromagnetic interaction is the basis for the creation of various electrical appliances, radios, televisions, computers, etc. It is about a thousand times weaker than a strong one, but much longer-range.

Without electromagnetic interactions there would be no atoms, molecules, macro-objects, heat and light.

3. Weak interaction perhaps between various particles, except for the photon, it is short-range and manifests itself at distances smaller than the size of the atomic nucleus 10 -15 - 10 -22 cm. Weak interaction is weaker than strong interaction and processes with weak interaction proceed more slowly than with strong interaction. Responsible for the decay of unstable particles (for example, the transformation of a neutron into a proton, electron, antineutrino). It is due to this interaction that most particles are unstable. The weak interaction carriers are ions, particles with a mass 100 times greater than the mass of protons and neutrons. Due to this interaction, the Sun shines (a proton turns into a neutron, positron, neutrino, the emitted neutrino has a huge penetrating ability).

Without weak interactions, nuclear reactions in the depths of the Sun and stars would not be possible, and new stars would not arise.

4. Gravitational interaction the weakest, not taken into account in theory elementary particles, since at their characteristic distances (10 -13 cm) the effects are small, and at ultra-small distances (10 -33 cm) and at ultra-high energies, gravity becomes important and the unusual properties of the physical vacuum begin to appear.

Gravity (from the Latin gravitas - “gravity”) - the fundamental interaction is long-range (this means that no matter how massive a body moves, at any point in space the gravitational potential depends only on the position of the body at a given moment in time) and all material bodies are subject to it . Basically, gravity plays a decisive role on a cosmic scale, the Megaworld.

Within the framework of classical mechanics, gravitational interaction is described law of universal gravitation Newton, who states that the force of gravitational attraction between two material points of mass m 1 and m 2 separated by distance R, There is

Where G- gravitational constant.

Without gravitational interactions there were no galaxies, stars, planets, or evolution of the Universe.

The time during which the transformation of elementary particles occurs depends on the strength of interaction (with strong interaction, nuclear reactions occur within 10 -24 - 10 -23 s., with electromagnetic - changes occur within 10 -19 - 10 -21 s., with weak disintegration within 10 -10 s.).

All interactions are necessary and sufficient for the construction of a complex and diverse material world, from which, according to scientists, one can obtain superpower(at very high temperatures or energies, all four interactions are combined in one).

FUNDAMENTAL INTERACTIONS, 4 FUNDAMENTAL INTERACTIONS, 4 types of interactions between elementary particles, explaining everything physical phenomena at the micro or macro level. Fundamental interactions include (in order of increasing intensity) gravitational, weak, electromagnetic and strong interactions. Gravitational interaction exists between all elementary particles and determines the gravitational attraction of all bodies to each other at any distance (see law of universal gravitation); it is negligibly small in physical processes in the microcosm, but plays a major role, for example, in cosmogony. Weak interaction appears only at distances of about 10-18 m and causes decay processes (for example, beta decay of some elementary particles and nuclei). Electromagnetic interaction exists at any distance between elementary particles having an electric charge or magnetic moment; in particular, it determines the connection between electrons and nuclei in atoms, and is also responsible for all types of electromagnetic radiation. Strong interaction manifests itself at distances of about 10-15 m and determines the existence of atomic nuclei. Perhaps all types of fundamental interactions have general nature and serve as various manifestations of a single fundamental interaction. This is fully confirmed for electromagnetic and weak fundamental interactions (the so-called electroweak interaction). The hypothetical unification of the electroweak and strong interactions is called the Great Unification, and all 4 fundamental interactions are called superunification; experimental verification of these hypotheses requires energies unattainable with modern accelerators.

Modern encyclopedia. 2000 .

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The ability to interact is the most important and integral property of matter. It is interactions that ensure the unification of various material objects of the mega-, macro- and microworld into systems. All famous modern science forces are reduced to four types of interactions, which are called fundamental: gravitational, electromagnetic, weak and strong.

Gravitational interaction first became the object of study of physics in the 17th century. I. Newton's theory of gravity, which is based on the law of universal gravitation, has become one of the components of classical mechanics. The law of universal gravitation states: between two bodies there is an attractive force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them (2.3). Any material particle is a source of gravitational influence and experiences it on itself. As the mass increases, gravitational interactions increase, i.e., the greater the mass of the interacting substances, the stronger the gravitational forces. The forces of gravity are forces of attraction. IN lately physicists have suggested the existence of gravitational repulsion, which acted in the very first moments of the existence of the Universe (4.2), but this idea has not yet been confirmed. Gravitational interaction is the weakest currently known. The gravitational force acts over very large distances; its intensity decreases with increasing distance, but does not disappear completely. It is believed that the carrier of gravitational interaction is the hypothetical particle graviton. In the microworld, gravitational interaction does not play a significant role, but in macro- and especially mega-processes it plays a leading role.

Electromagnetic interaction became the subject of study in physics of the 19th century. The first unified theory of the electromagnetic field was the concept of J. Maxwell (2.3). Unlike the gravitational force, electromagnetic interactions exist only between charged particles: the electric field is between two stationary charged particles, the magnetic field is between two moving charged particles. Electromagnetic forces can be either attractive or repulsive forces. Likely charged particles repel, oppositely charged particles attract. The carriers of this type of interaction are photons. Electromagnetic interaction manifests itself in the micro-, macro- and mega-worlds.

In the middle of the 20th century. was created quantum electrodynamics– the theory of electromagnetic interaction, which satisfied the basic principles of quantum theory and the theory of relativity. In 1965, its authors S. Tomanaga, R. Feynman and J. Schwinger were awarded the Nobel Prize. Quantum electrodynamics describes the interaction of charged particles - electrons and positrons.

Weak interaction was discovered only in the 20th century, in the 1960s. a general theory of weak interaction was constructed. The weak force is associated with the decay of particles, so its discovery followed only after the discovery of radioactivity. When observing radioactive decay particles, phenomena were discovered that seemed to contradict the law of conservation of energy. The fact is that during the decay process, part of the energy “disappeared.” Physicist W. Pauli suggested that during the process of radioactive decay of a substance, a particle with high penetrating power is released along with an electron. This particle was later named "neutrino". It turned out that as a result of weak interactions, the neutrons that make up the atomic nucleus decay into three types of particles: positively charged protons, negatively charged electrons and neutral neutrinos. The weak interaction is much smaller than the electromagnetic interaction, but greater than the gravitational interaction, and unlike them, it spreads over small distances - no more than 10-22 cm. That is why the weak interaction was not observed experimentally for a long time. The carriers of the weak interaction are bosons.

In the 1970s a general theory of electromagnetic and weak interaction was created, called theory of electroweak interaction. Its creators S. Weinberg, A. Salam and S. Glashow in 1979 received Nobel Prize. The theory of electroweak interaction considers two types of fundamental interactions as manifestations of a single, deeper one. Thus, at distances greater than 10-17 cm, the electromagnetic aspect of phenomena predominates; at shorter distances, both the electromagnetic and weak aspects are equally important. The creation of the theory under consideration meant that, united in classical physics of the 19th century, within the framework of the Faraday-Maxwell theory, electricity, magnetism and light in the last third of the 20th century. supplemented by the phenomenon of weak interaction.

Strong interaction was also discovered only in the 20th century. It holds protons in the nucleus of an atom, preventing them from scattering under the influence of electromagnetic repulsive forces. Strong interaction occurs at distances of no more than 10-13 cm and is responsible for the stability of nuclei. The nuclei of elements at the end of the periodic table are unstable because their radius is large and, accordingly, the strong interaction loses its intensity. Such nuclei are subject to decay, which is called radioactive. Strong interaction is responsible for education atomic nuclei, only heavy particles participate in it: protons and neutrons. Nuclear interactions do not depend on the charge of particles; the carriers of this type of interaction are gluons. Gluons are combined into a gluon field (similar to an electromagnetic field), due to which the strong interaction occurs. In its power, the strong interaction surpasses other known ones and is a source of enormous energy. An example of strong interaction is thermonuclear reactions in the Sun and other stars. The principle of strong interaction was used to create hydrogen weapons.

The theory of strong interaction is called quantum chromodynamics. According to this theory, the strong interaction is the result of the exchange of gluons, which results in the connection of quarks in hadrons. Quantum chromodynamics continues to develop, and although it cannot yet be considered a complete concept of the strong interaction, nevertheless this physical theory has a solid experimental basis.

In modern physics, the search continues for a unified theory that would explain all four types of fundamental interactions. The creation of such a theory would also mean the construction of a unified concept of elementary particles. This project was called the “Great Unification”. The basis for the belief that such a theory is possible is the fact that at short distances (less than 10-29 cm) and at high energy(more than 1014 GeV) electromagnetic, strong and weak interactions are described in the same way, which means their common nature. However, this conclusion is still only theoretical; it has not yet been possible to verify it experimentally.

Various competing Grand Unified theories interpret cosmology (4.2) differently. For example, it is assumed that at the moment of the birth of our Universe, conditions existed in which all four fundamental interactions manifested themselves in the same way. Creating a theory that explains all four types of interactions on a unified basis will require a synthesis of the theory of quarks, quantum chromodynamics, modern cosmology and relativistic astronomy.

However, the search for a unified theory of four types of fundamental interactions does not mean that the emergence of other interpretations of matter is impossible: the discovery of new interactions, the search for new elementary particles, etc. Some physicists express doubts about the possibility of a unified theory. Thus, the creators of synergetics I. Prigogine and I. Stengers in the book “Time, Chaos, Quantum” write: “the hope for building such a “theory of everything” from which it would be possible to deduce full description physical reality, will have to be abandoned,” and justify their thesis by the laws formulated within the framework of synergetics (7.2).

Conservation laws played an important role in understanding the mechanisms of interaction of elementary particles, their formation and decay. In addition to the conservation laws operating in the macroworld (the law of conservation of energy, the law of conservation of momentum and the law of conservation of angular momentum), new ones were discovered in the physics of the microworld: the law of conservation of baryon, lepton charges, strangeness, etc.

Each conservation law is associated with some kind of symmetry in the surrounding world. In physics, symmetry is understood as invariance, the immutability of a system relative to its transformations, i.e., relative to changes in the series physical conditions. The German mathematician Emma Noether established a connection between the properties of space and time and the conservation laws of classical physics. A fundamental theorem of mathematical physics, called Noether's theorem, states that from the homogeneity of space the law of conservation of momentum follows, from the homogeneity of time the law of conservation of energy follows, and from the isotropy of space the law of conservation of angular momentum follows. These laws are fundamental in nature and are valid for all levels of existence of matter.

The law of conservation and transformation of energy states that energy does not disappear and does not appear again, but only passes from one form to another. The law of conservation of momentum postulates the constancy of momentum closed system over time. The law of conservation of angular momentum states that the angular momentum of a closed-loop system remains constant over time. Conservation laws are a consequence of symmetry, i.e. invariance, immutability of the structure of material objects relative to transformations, or changes in the physical conditions of their existence.

That various substances contain quite a lot of elementary particles, fundamental physical interactions are represented by four types: strong, electromagnetic, weak and gravitational. The latter is considered the most comprehensive.

All macrobodies and microparticles, without exception, are subject to gravity. Absolutely all elementary particles are subject to gravitational influence. It manifests itself in the form of universal gravity. This fundamental interaction controls the most global processes occurring in the Universe. Gravity provides structural stability solar system.

According to modern ideas, fundamental interactions arise due to the exchange of particles. Gravity is formed through the exchange of gravitons.

Fundamental interactions - gravitational and electromagnetic - are long-range in nature. The corresponding forces can manifest themselves over considerable distances. These fundamental interactions have their own characteristics.

Described by charges of the same type (electric). In this case, the charges can have both positive and negative sign. Electromagnetic forces, unlike (gravity), can act as repulsive and attractive forces. This interaction causes chemical and physical properties various substances, materials, living tissue. Electromagnetic forces drive both electronic and electrical equipment, connecting charged particles with each other.

Fundamental interactions are known outside a small circle of astronomers and physicists to varying degrees.

Despite being less well known (compared to other types), weak forces play an important role in the life of the Universe. So, if there were no weak interaction, the stars and the Sun would go out. These forces are short-range. The radius is approximately a thousand times smaller than that of nuclear forces.

Nuclear forces are considered the most powerful of all. The strong interaction determines the bonds only between hadrons. The nuclear forces acting between nucleons are its manifestation. approximately one hundred times more powerful than electromagnetic. Differing from gravitational (as, in fact, from electromagnetic), it is short-range at a distance of more than 10-15 m. In addition, it can be described using three charges that form complex combinations.

Range is considered the most important feature of fundamental interaction. The radius of action is the maximum distance that is formed between particles. Outside of this, interaction can be neglected. A small radius characterizes the force as short-range, a large radius as long-range.

As noted above, weak and strong interactions are considered short-range. Their intensity decreases quite quickly as the distance between particles increases. These interactions manifest themselves at small distances inaccessible to perception through the senses. In this regard, these forces were discovered much later than the others (only in the twentieth century). In this case, quite complex experimental facilities. Gravitational and electromagnetic types of fundamental interactions are considered long-range. They are characterized by a slow decrease as the distance between particles increases and are not endowed with a finite range of action.

The ability to interact is the most important and integral property of matter. It is interactions that ensure the unification of various material objects of the mega-, macro- and microworld into systems. All forces known to modern science come down to four types of interactions, which are called fundamental: gravitational, electromagnetic, weak and strong.

Gravitational interaction first became the object of study of physics in the 17th century. I. Newton's theory of gravity, which is based on the law of universal gravitation, has become one of the components of classical mechanics. Any material particle is a source of gravitational influence and experiences it on itself. As mass increases, gravitational interactions increase, i.e. The greater the mass of interacting substances, the stronger the gravitational forces. The forces of gravity are forces of attraction. Gravitational interaction is the weakest currently known. The gravitational force acts over very large distances; its intensity decreases with increasing distance, but does not disappear completely. It is believed that the carrier of gravitational interaction is the hypothetical particle graviton. In the microworld, gravitational interaction does not play a significant role, but in macro- and especially mega-processes it plays a leading role.

Electromagnetic interaction became the subject of study in physics of the 19th century. The first unified theory of the electromagnetic field was the concept of J. Maxwell. Electromagnetic interactions exist only between charged particles: the electric field is between two stationary charged particles, the magnetic field is between two moving charged particles. Electromagnetic forces can be either attractive or repulsive forces. Likely charged particles repel, oppositely charged particles attract. The carriers of this type of interaction are photons. Electromagnetic interaction manifests itself in the micro-, macro- and mega-worlds.

In the middle of the 20th century. was created quantum electrodynamics– the theory of electromagnetic interaction, which describes the interaction of charged particles - electrons and positrons. In 1965, its authors S. Tomanaga, R. Feynman and J. Schwinger were awarded the Nobel Prize.

Weak interaction was discovered only in the 20th century, in the 60s. a general theory of weak interaction was constructed. The weak force is associated with the decay of particles, so its discovery followed only after the discovery of radioactivity. Physicist W. Pauli suggested that during the process of radioactive decay of a substance, a particle with high penetrating power is released along with an electron. This particle was later named "neutrino". It turned out that as a result of weak interactions, the neutrons that make up the atomic nucleus decay into three types of particles: positively charged protons, negatively charged electrons and neutral neutrinos. The weak interaction is much smaller than the electromagnetic one, but larger than the gravitational one, and unlike them, it spreads over small distances - no more than 10–22 cm. That is why the weak interaction was not observed experimentally for a long time. The carriers of the weak interaction are bosons.

In the 70s XX century a general theory of electromagnetic and weak interaction was created, called theory of electroweak interaction. Its creators S. Weinberg, A. Sapam and S. Glashow received the Nobel Prize in 1979. The theory of electroweak interaction considers two types of fundamental interactions as manifestations of a single, deeper one. Thus, at distances greater than 10–17 cm, the electromagnetic aspect of phenomena predominates; at shorter distances, both the electromagnetic and weak aspects are equally important. The creation of the theory under consideration meant that, united in classical physics of the 19th century, within the framework of the Faraday–Maxwell theory, electricity, magnetism and light, in the last third of the 20th century. supplemented by the phenomenon of weak interaction.

Strong interaction was also discovered only in the 20th century. It holds protons in the nucleus of an atom, preventing them from scattering under the influence of electromagnetic repulsive forces. Strong interaction occurs at distances of no more than 10–13 cm and is responsible for the stability of nuclei. The kernels of the elements located at the end of the table D.I. Mendeleev are unstable because their radius is large and, accordingly, the strong interaction loses its intensity. Such nuclei are subject to decay, which is called radioactive. Strong interaction is responsible for the formation of atomic nuclei; only heavy particles participate in it: protons and neutrons. Nuclear interactions do not depend on the charge of particles; the carriers of this type of interaction are gluons. Gluons are combined into a gluon field (similar to an electromagnetic field), due to which the strong interaction occurs. In its power, the strong interaction surpasses other known ones and is a source of enormous energy. An example of strong interaction is thermonuclear reactions in the Sun and other stars. The principle of strong interaction was used to create hydrogen weapons.

The theory of strong interaction is called quantum chromodynamics. According to this theory, the strong interaction is the result of the exchange of gluons, which results in the connection of quarks in hadrons. Quantum chromodynamics continues to develop; it cannot yet be considered a complete concept of the strong interaction, but it has a solid experimental basis.

In modern physics, the search continues for a unified theory that would explain all four types of fundamental interactions. The creation of such a theory would also mean the construction of a unified concept of elementary particles. This project was called the “Great Unification”. The basis for the belief that such a theory is possible is the fact that at short distances (less than 10–29 cm) and at high energies (more than 10 14 GeV), electromagnetic, strong and weak interactions are described in the same way, which means their nature is common. However, this conclusion is only theoretical; it has not yet been possible to verify it experimentally.