Interaction in physics is the influence of bodies or particles on each other, leading to a change in their motion.
Proximity and long-range action (or action at a distance). There have long been two points of view in physics about how bodies interact. The first of them assumed the presence of some agent (for example, ether), through which one body transmits its influence to another, and with terminal speed. This is the theory of short-range action. The second assumed that the interaction between bodies occurs through empty space, which does not take any part in the transmission of interaction, and the transmission occurs instantly. This is the theory of long-range action. She seemed to have finally won after Newton discovered the law universal gravity. For example, it was believed that the movement of the Earth should immediately lead to a change in the gravitational force acting on the Moon. In addition to Newton himself, the concept of long-range action was later adhered to by Coulomb and Ampere.
After the discovery and study of the electromagnetic field (see Electromagnetic field), the theory of long-range action was rejected, since it was proven that the interaction of electrically charged bodies does not occur instantly, but with a finite speed ( equal speed light: c = 3 108 m/s) and the movement of one of the charges leads to a change in the forces acting on other charges, not instantly, but after some time. Arose new theory short-range interaction, which was then extended to all other types of interactions. According to the theory of short-range action, interaction is carried out through corresponding fields surrounding the bodies and continuously distributed in space (i.e., the field is the intermediary that transmits the action of one body to another). Interaction electric charges- through an electromagnetic field, universal gravity - through a gravitational field.
Today, physics knows four types fundamental interactions existing in nature (in order of increasing intensity): gravitational, weak, electromagnetic and strong interactions.
Fundamental interactions are those that cannot be reduced to other types of interactions.
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Fundamental interactions differ in intensity and range of action (see Table 1.1). The radius of action is the maximum distance between particles, beyond which their interaction can be neglected.
According to the radius of action, fundamental interactions are divided into long-range (gravitational and electromagnetic) and short-range (weak and strong) (see Table 1.1).
Gravitational interaction is universal: all bodies in nature participate in it - from stars, planets and galaxies to microparticles: atoms, electrons, nuclei. Its range of action is infinity. However, as for elementary particles microworld, and for the objects surrounding us in the macroworld of power gravitational interaction so small that they can be neglected (see Table 1.1). It becomes noticeable with increasing mass of interacting bodies and therefore determines behavior celestial bodies and the formation and evolution of stars.
Weak interaction is inherent in all elementary particles except the photon. It is responsible for the majority nuclear reactions decay and many transformations of elementary particles.
Electromagnetic interaction determines the structure of matter, connecting electrons and nuclei in atoms and molecules, combining atoms and molecules into various substances. It determines chemical and biological processes. Electromagnetic interaction is the cause of such phenomena as elasticity, friction, viscosity, magnetism and constitutes the nature of the corresponding forces. It does not have a significant effect on the motion of macroscopic electrically neutral bodies.
The strong interaction occurs between hadrons, which is what holds the nucleons in the nucleus.
In 1967, Sheldon Glashow, Abdus Salam and Steven Weinberg created a theory combining electromagnetic and weak interaction into a single electroweak interaction with a range of 10~17 m, within which the difference between weak and electromagnetic interactions disappears.
Currently, the theory of grand unification has been put forward, according to which there are only two types of interactions: unified, which includes strong, weak and electromagnetic interactions, and gravitational interaction.
There is also an assumption that all four interactions are special cases of the manifestation of a single interaction.
In mechanics, the mutual action of bodies on each other is characterized by force (see Force). More general characteristic interaction is potential energy(see Potential energy).
Forces in mechanics are divided into gravitational, elastic and frictional. As mentioned above, the nature of mechanical forces is determined by gravitational and electromagnetic interactions. Only these interactions can be considered as forces in the sense of Newtonian mechanics. Strong (nuclear) and weak interactions manifest themselves at such small distances that Newton’s laws of mechanics, and with them the concept mechanical force lose their meaning. Therefore, the term “force” in these cases should be perceived as “interaction”.
1.1. Gravity.
1.2. Electromagnetism.
1.3. Weak interaction.
1.4. The problem of the unity of physics.
2. Classification of elementary particles.
2.1. characteristic subatomic particles.
2.2. leptons.
2.3. Hadrons.
2.4. Particles are carriers of interactions.
3. Theories of elementary particles.
3.1. Quantum electrodynamics.
3.2. Quark theory.
3.3. Theory of electroweak interaction.
3.4. Quantum chromodynamics.
3.5. On the way to great unification.
Bibliography.
Introduction.
In the middle and second half of the twentieth century, truly amazing results were obtained in those branches of physics that study the fundamental structure of matter. First of all, this manifested itself in the discovery of a whole host of new subatomic particles. They are usually called elementary particles, but not all of them are truly elementary. Many of them, in turn, consist of even more elementary particles. The world of subatomic particles is truly diverse. These include protons and neutrons that make up atomic nuclei, as well as electrons orbiting the nuclei. But there are also particles that are practically never found in the matter around us. Their life time is extremely short, it is the smallest fractions of a second. After this extremely short time, they disintegrate into ordinary particles. There are an amazing number of such unstable short-lived particles: several hundred of them are already known. In the 1960s and 1970s, physicists were completely baffled by the number, variety, and strangeness of the newly discovered subatomic particles. There seemed to be no end to them. It is completely unclear why there are so many particles. Are these elementary particles chaotic and random fragments of matter? Or perhaps they hold the key to understanding the structure of the Universe? The development of physics in subsequent decades showed that there is no doubt about the existence of such a structure. At the end of the twentieth century. physics is beginning to understand the significance of each of the elementary particles. The world of subatomic particles is characterized by a deep and rational order. This order is based on fundamental physical interactions.
1. Fundamental physical interactions.
In your Everyday life a person is faced with many forces acting on their bodies. Here is the force of the wind or the oncoming flow of water, air pressure, a powerful release of explosive chemicals, human muscular strength, the weight of heavy objects, the pressure of light quanta, the attraction and repulsion of electrical charges, seismic waves that sometimes cause catastrophic destruction, and volcanic eruptions that led to the death of civilization, etc. Some forces act directly upon contact with the body, others, for example, gravity, act at a distance, through space. But, as it turned out as a result of the development of theoretical natural science, despite such great diversity, all forces operating in nature can be reduced to just four fundamental interactions. It is these interactions that are ultimately responsible for all changes in the world; they are the source of all transformations of bodies and processes. The study of the properties of fundamental interactions is main task modern physics.
Gravity.
In the history of physics, gravity (gravity) became the first of the four fundamental interactions to be the subject of scientific research. After its appearance in the 17th century. Newton's theory of gravity - the law of universal gravitation - managed for the first time to realize the true role of gravity as a force of nature. Gravity has a number of features that distinguish it from other fundamental interactions. The most surprising feature of gravity is its low intensity. The magnitude of gravitational interaction between the components of a hydrogen atom is 10n, where n = - 3 9, based on the force of interaction of electric charges. (If the dimensions of the hydrogen atom were determined by gravity, and not by the interaction between electric charges, then the lowest (closest to the nucleus) orbit of the electron would be larger in size than the observable part of the Universe!) (If the dimensions of the hydrogen atom were determined by gravity, and not by the interaction between electrical charges, then the lowest (closest to the nucleus) electron orbit would be larger in size than the observable part of the Universe!). It may seem surprising that we feel gravity at all, since it is so weak. How can she become the dominant force in the Universe? It's all about the second amazing feature of gravity - its universality. Nothing in the Universe is free from gravity. Each particle experiences the action of gravity and is itself a source of gravity. Since every particle of matter exerts a gravitational pull, gravity increases as larger clumps of matter form. We feel gravity in everyday life because all the atoms of the Earth work together to attract us. And although the effect of the gravitational attraction of one atom is negligible, the resulting force of attraction from all atoms can be significant. Gravity is a long-range force of nature. This means that, although the intensity of gravitational interaction decreases with distance, it spreads in space and can affect bodies very distant from the source. On an astronomical scale, gravitational interactions tend to play a major role. Thanks to long-range action, gravity prevents the Universe from falling apart: it holds planets in orbits, stars in galaxies, galaxies in clusters, clusters in the Metagalaxy. The gravitational force acting between particles is always an attractive force: it tends to bring the particles closer together. Gravitational repulsion has never been observed before (Although in the traditions of quasi-scientific mythology there is a whole field called levitation - the search for the “facts” of antigravity). Since the energy stored in any particle is always positive and gives it positive mass, particles under the influence of gravity always tend to get closer. What is gravity, a certain field or a manifestation of the curvature of space-time - there is still no clear answer to this question. As we have already noted, there are different opinions and concepts of physicists on this matter.
Electromagnetism.
By size electrical forces far superior to gravity. Unlike the weak gravitational interaction, the electrical forces acting between bodies of normal size can be easily observed. Electromagnetism has been known to people since time immemorial (auroras, lightning flashes, etc.). For a long time, electrical and magnetic processes were studied independently of each other. As we already know, the decisive step in the knowledge of electromagnetism was made in the middle of the 19th century. J.C. Maxwell, who combined electricity and magnetism in a unified theory of electromagnetism - the first unified field theory. The existence of the electron was firmly established in the 90s of the last century. It is now known that the electric charge of any particle of matter is always a multiple of the fundamental unit of charge - a kind of “atom” of charge. Why this is so is an extremely interesting question. However, not all material particles are carriers of electric charge. For example, the photon and neutrino are electrically neutral. In this respect, electricity differs from gravity. All material particles create a gravitational field, whereas with electromagnetic field Only charged particles are bound. Like electric charges, like magnetic poles repel, and opposite ones attract. However, unlike electric charges, magnetic poles do not occur individually, but only in pairs - North Pole and the south pole. Since ancient times, attempts have been known to obtain, by dividing a magnet, only one isolated magnetic pole - a monopole. But they all ended in failure. Maybe the existence of isolated magnetic poles impossible in nature? There is no definite answer to this question yet. Some theoretical concepts allow for the possibility of a monopole. Like electrical and gravitational interactions, the interaction of magnetic poles obeys the inverse square law. Consequently, electric and magnetic forces are “long-range”, and their effect is felt at large distances from the source. Thus, the Earth's magnetic field extends far into outer space. The Sun's powerful magnetic field fills the entire Solar System. There are also galactic magnetic fields. Electromagnetic interaction determines the structure of atoms and is responsible for the vast majority of physical and chemical phenomena and processes (except nuclear).
Weak interaction.
Physics has moved slowly towards identifying the existence of the weak interaction. The weak force is responsible for particle decays; and therefore its manifestation was confronted with the discovery of radioactivity and the study of beta decay. Beta decay was found in highest degree strange feature. Research led to the conclusion that this decay violates one of the fundamental laws of physics - the law of conservation of energy. It seemed that in this decay part of the energy disappeared somewhere. In order to “save” the law of conservation of energy, W. Pauli suggested that, together with the electron, during beta decay, another particle is emitted. It is neutral and has an unusually high penetrating ability, as a result of which it could not be observed. E. Fermi called the invisible particle "neutrino". But the prediction and detection of neutrinos is only the beginning of the problem, its formulation. It was necessary to explain the nature of neutrinos, but there remained a lot of mystery here. The fact is that both electrons and neutrinos were emitted by unstable nuclei. But it was irrefutably proven that there are no such particles inside nuclei. How did they arise? It was suggested that electrons and neutrinos do not exist in the nucleus in a “ready form”, but are somehow formed from the energy of the radioactive nucleus. Further research showed that the neutrons included in the nucleus, left to their own devices, after a few minutes decay into a proton, electron and neutrino, i.e. instead of one particle, three new ones appear. The analysis led to the conclusion that known forces cannot cause such disintegration. It was apparently generated by some other, unknown force. Research has shown that this force corresponds to some weak interaction. It is much weaker than electromagnetic, although stronger than gravitational. It spreads over very short distances. The radius of the weak interaction is very small. The weak interaction stops at a distance greater than 10n cm (where n = - 1 6) from the source and therefore cannot affect macroscopic objects, but is limited to individual subatomic particles. Subsequently, it turned out that most unstable elementary particles participate in weak interactions. The theory of weak interaction was created in the late 60s by S. Weinberg and A. Salam. Since Maxwell's theory of the electromagnetic field, the creation of this theory was the largest step towards the unity of physics. 10.
Strong interaction.
The last in the series of fundamental interactions is the strong interaction, which is a source of enormous energy. Most typical example The energy released by the strong interaction is our Sun. In the depths of the Sun and stars, starting from a certain time, thermonuclear reactions caused by strong interaction continuously occur. But man has also learned to release strong interactions: a hydrogen bomb has been created, technologies for controlled thermonuclear reactions have been designed and improved. Physics came to the idea of the existence of strong interaction during the study of the structure atomic nucleus. Some force must hold the protons in the nucleus, preventing them from scattering under the influence of electrostatic repulsion. Gravity is too weak for this; Obviously, some new interaction is needed, moreover, stronger than electromagnetic. It was subsequently discovered. It turned out that although the strong interaction significantly exceeds all other fundamental interactions in its magnitude, it is not felt outside the nucleus. Radius of action new strength turned out to be very small. The strong force drops off sharply at a distance from the proton or neutron greater than about 10n cm (where n = - 13). In addition, it turned out that not all particles experience strong interactions. It is experienced by protons and neutrons, but electrons, neutrinos and photons are not subject to it. Only heavier particles participate in strong interactions. The theoretical explanation of the nature of the strong interaction has been difficult to develop. A breakthrough occurred in the early 60s, when the quark model was proposed. In this theory, neutrons and protons are considered not as elementary particles, but as composite systems built from quarks. Thus, in fundamental physical interactions the difference between long-range and short-range forces is clearly visible. On the one hand, there are interactions of unlimited range (gravity, electromagnetism), and on the other, interactions of short range (strong and weak). The world of physical elements as a whole unfolds in the unity of these two polarities and is the embodiment of the unity of the extremely small and the extremely large - short-range action in the microworld and long-range action throughout the Universe.
The problem of the unity of physics.
Knowledge is a generalization of reality, and therefore the goal of science is the search for unity in nature, linking disparate fragments of knowledge into a single picture. In order to create unified system, need to open connecting link between different branches of knowledge, some fundamental relationship. The search for such connections and relationships is one of the main tasks of scientific research. Whenever it is possible to establish such new connections, the understanding of the surrounding world deepens significantly, new ways of knowing are formed that point the way to previously unknown phenomena. Establishing deep connections between different areas of nature is both a synthesis of knowledge and a method that guides scientific research along new, untrodden roads. Newton's discovery of the connection between the attraction of bodies under terrestrial conditions and the motion of planets marked the birth classical mechanics, on the basis of which the technological base of modern civilization is built. Establishing a connection thermodynamic properties gas with the chaotic movement of molecules put the atomic-molecular theory of matter on a solid basis. In the middle of the last century, Maxwell created a unified electromagnetic theory that covered both electrical and magnetic phenomena. Then, in the 20s of our century, Einstein made attempts to combine unified theory electromagnetism and gravity. But by the middle of the twentieth century. The situation in physics has changed radically: two new fundamental interactions have been discovered - strong and weak, i.e. while creating unified physics we no longer have to reckon with two, but with four fundamental interactions. This somewhat cooled the ardor of those who hoped for fast decision this problem. But the idea itself was not seriously questioned, and the enthusiasm for the idea of a single description did not go away. There is a point of view that all four (or at least three) interactions represent phenomena of the same nature and their unified theoretical description must be found. The prospect of creating a unified theory of the world of physical elements based on a single fundamental interaction remains very attractive. This is the main dream of 20th century physicists. But for a long time it remained only a dream, and a very vague one. However, in the second half of the twentieth century. there were prerequisites for the realization of this dream and the confidence that this was by no means a matter of the distant future. It looks like it could soon become a reality. The decisive step towards a unified theory was made in the 60-70s. with the creation first of the theory of quarks, and then of the theory of electroweak interaction. There is reason to believe that we are on the threshold of a more powerful and deeper unification than ever before. There is a growing belief among physicists that the contours of a unified theory of all fundamental interactions - the Grand Unification - are beginning to emerge.
2 . Classification of elementary particles.
For a long time, man has sought to know and understand the physical world around him. It turns out that all the infinite variety of physical processes occurring in our world can be explained by the existence in nature of a very small number of fundamental interactions. Their interaction with each other explains the orderly arrangement of celestial bodies in the Universe. They are the “elements” that move celestial bodies, generate light and make life itself possible (see. Application
).
Thus, all processes and phenomena in nature, be it an apple falling, a supernova explosion, a penguin jumping, or the radioactive decay of substances, occur as a result of these interactions.
The structure of the substance of these bodies is stable due to the bonds between its constituent particles.
1. TYPES OF INTERACTIONS
Despite the fact that matter contains a large number of elementary particles, there are only four types of fundamental interactions between them: gravitational, weak, electromagnetic and strong.
The most comprehensive is gravitational
interaction
. All material interactions, without exception, are subject to it - both microparticles and macrobodies. This means that all elementary particles participate in it. It manifests itself in the form of universal gravity. Gravity
(from Latin Gravitas - heaviness) controls the most global processes in the Universe, in particular, ensures the structure and stability of our solar system. According to modern concepts, each of the interactions arises as a result of the exchange of particles called carriers of this interaction. Gravitational interaction is carried out through exchange gravitons
.
, like gravitational, is long-range in nature: the corresponding forces can manifest themselves at very significant distances. Electromagnetic interaction is described by charges of one type (electric), but these charges can already have two signs - positive and negative. Unlike gravity, electromagnetic forces can be both attractive and repulsive forces. Physical and Chemical properties of various substances, materials and living tissue itself are determined by this interaction. It also powers all electrical and electronic equipment, i.e. connects only charged particles with each other. Theory electromagnetic interaction in the macrocosm it is called classical electrodynamics.
Weak interaction
less known outside narrow circle physicists and astronomers, but this does not in any way detract from its significance. Suffice it to say that if it were not there, the Sun and other stars would go out, because in the reactions that ensure their glow, the weak interaction plays a very important role. important role. The weak interaction is short-range: its radius is approximately 1000 times smaller than that of nuclear forces.
Strong interaction
– the most powerful of all the others. It defines connections only between hadrons. Nuclear forces acting between nucleons in an atomic nucleus are a manifestation of this type of interaction. It is about 100 times stronger than electromagnetic energy. Unlike the latter (and also gravitational), it is, firstly, short-range at a distance greater than 10–15 m (on the order of the size of the nucleus), the corresponding forces between protons and neutrons, sharply decreasing, cease to bind them to each other. Secondly, it can be described satisfactorily only by means of three charges (colors) forming complex combinations.
Table 1 roughly presents the most important elementary particles belonging to the main groups (hadrons, leptons, interaction carriers).
Table 1
Participation of basic elementary particles in interactions
The most important characteristic of a fundamental interaction is its range of action. The radius of action is the maximum distance between particles, beyond which their interaction can be neglected (Table 2). At a small radius the interaction is called short-acting , with large – long-range .
table 2
Main characteristics of fundamental interactions
Strong and weak interactions are short-range . Their intensity decreases rapidly with increasing distance between particles. Such interactions occur at a short distance, inaccessible to perception by the senses. For this reason, these interactions were discovered later than others (only in the 20th century) using complex experimental facilities. Electromagnetic and gravitational interactions are long-range . Such interactions decrease slowly with increasing distance between particles and do not have a finite range of action.
2. INTERACTION AS A CONNECTION OF STRUCTURES OF MATTER
In the atomic nucleus, the bond between protons and neutrons determines strong interaction . It provides exceptional core strength, which underlies the stability of the substance under terrestrial conditions.
Weak interaction a million times less intense than strong. It acts between most elementary particles located at a distance of less than 10–17 m from each other. Weak interaction determines the radioactive decay of uranium and thermonuclear fusion reactions in the Sun. As you know, it is the radiation of the Sun that is the main source of life on Earth.
Electromagnetic interaction , being long-range, determines the structure of matter beyond the range of the strong interaction. The electromagnetic force binds electrons and nuclei in atoms and molecules. It combines atoms and molecules into various substances and determines chemical and biological processes. This interaction is characterized by forces of elasticity, friction, viscosity, and magnetic forces. In particular, the electromagnetic repulsion of molecules located at short distances causes a ground reaction force, as a result of which we, for example, do not fall through the floor. Electromagnetic interaction does not have a significant effect on the mutual motion of macroscopic bodies large mass, since each body is electrically neutral, i.e. it contains approximately same number positive and negative charges.
Gravitational interaction directly proportional to the mass of interacting bodies. Due to the small mass of elementary particles, the gravitational interaction between particles is small compared to other types of interaction, therefore, in the processes of the microworld, this interaction is insignificant. As the mass of interacting bodies increases (i.e., as the number of particles they contain increases), the gravitational interaction between the bodies increases in direct proportion to their mass. In this regard, in the macrocosm, when considering the movement of planets, stars, galaxies, as well as the movement of small macroscopic bodies in their fields, gravitational interaction becomes decisive. It holds the atmosphere, seas and everything living and nonliving on Earth, the Earth revolving in orbit around the Sun, the Sun within the Galaxy. Gravitational interaction plays a major role in the formation and evolution of stars. Fundamental interactions of elementary particles are depicted using special diagrams, in which a real particle corresponds to a straight line, and its interaction with another particle is depicted either by a dotted line or a curve (Fig. 1).
Diagrams of interactions of elementary particles
Modern physical concepts of fundamental interactions are constantly being refined. In 1967 Sheldon Glashow, Abdus Salam And Steven Weinberg created a theory according to which the electromagnetic and weak interactions are a manifestation of a single electroweak interaction. If the distance from an elementary particle is less than the radius of action weak forces(10–17 m), then the difference between electromagnetic and weak interactions disappears. Thus, the number of fundamental interactions was reduced to three.
The theory of the "Great Unification".
Some physicists, in particular G. Georgi and S. Glashow, suggested that during the transition to higher energies another merger should occur - the unification of the electroweak interaction with the strong one. The corresponding theoretical schemes are called the “Grand Unification” Theory. And this theory is currently being tested experimentally. According to this theory, which combines strong, weak and electromagnetic interactions, there are only two types of interactions: unified and gravitational. It is possible that all four interactions are only partial manifestations of a single interaction. The premises of such assumptions are considered when discussing the theory of the origin of the Universe (the Big Bang theory). Theory " Big Bang” explains how the combination of matter and energy gave birth to stars and galaxies.
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 - different particles, since the proton is electrically charged, but the 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, the 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. A 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. Carriers of weak interaction - vions, particles with a mass of 100 times more mass 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, is not taken into account in the theory of elementary particles, since at 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).
In everyday life, we encounter a variety of forces arising from the collision of bodies, friction, explosion, tension of a thread, compression of a spring, etc. However, all of these forces are the result of the electromagnetic interaction of atoms with each other. The theory of electromagnetic interaction was created by Maxwell in 1863.
Another long-known interaction is the gravitational interaction between bodies with mass. In 1915 Einstein created general theory relativity, which connected the gravitational field with the curvature of space-time.
In the 1930s It was discovered that the nuclei of atoms consist of nucleons, and neither electromagnetic nor gravitational interactions can explain what holds the nucleons in the nucleus. The strong interaction was proposed to describe the interaction of nucleons in a nucleus.
As we continued to study the microworld, it turned out that some phenomena are not described by the three types of interaction. Therefore, the weak interaction was proposed to describe the decay of the neutron and other similar processes.
Today all forces known in nature are the product of four fundamental interactions, which can be arranged in descending order of intensity in the following order:
- 1) strong interaction;
- 2) electromagnetic interaction;
- 3) weak interaction;
- 4) gravitational interaction.
Fundamental interactions are carried by elementary particles - carriers of fundamental interactions. These particles are called gauge bosons. The process of fundamental interactions of bodies can be represented in the following way. Each body emits particles - carriers of interactions, which are absorbed by another body. In this case, the bodies experience mutual influence.
Strong interaction can occur between protons, neutrons and other hadrons (see below). It is short-range and is characterized by a radius of action of forces of the order of 10 15 m. The carrier of strong interaction between hadrons is peonies, and the duration of the interaction is about 10 23 s.
Electromagnetic interaction has four orders of magnitude lower intensity compared to the strong interaction. It occurs between charged particles. Electromagnetic interaction is long-acting and is characterized by an infinite radius of action of forces. The carrier of electromagnetic interaction is photons, and the duration of the interaction is about 10–20 s.
Weak interaction has 20 orders of magnitude lower intensity compared to the strong interaction. It can occur between hadrons and leptons (see below). Leptons include, in particular, the electron and neutrino. An example of weak interaction is the neutron p-decay discussed above. The weak interaction is short-range and is characterized by a radius of action of forces of the order of 10 18 m. The carrier of the weak interaction is vector bosons, and the duration of the interaction is about 10 10 s.
Gravitational interaction has 40 orders of magnitude lower intensity compared to the strong interaction. It occurs between all particles. Gravitational interaction is long-acting and is characterized by an infinite radius of action of forces. The carrier of gravitational interaction may be gravitons. These particles have not yet been found, which may be due to the low intensity of gravitational interaction. It is also related to the fact that due to the small masses of elementary particles, this interaction in the processes of nuclear physics is insignificant.
In 1967, A. Salam and S. Weinberg proposed theory of electroweak interaction, which united electromagnetic and weak interactions. In 1973, the theory of strong interaction was created quantum chromodynamics. All this made it possible to create standard model elementary particles, describing electromagnetic, weak and strong interactions. All three types of interaction considered here arise as a consequence of the postulate that our world is symmetric with respect to three types of gauge transformations.