How does a magnet work? The influence of the magnetic field on the human body. The benefits of magnetotherapy

MAGNETS AND MAGNETIC PROPERTIES OF THE SUBSTANCE
The simplest manifestations of magnetism have been known for a very long time and are familiar to most of us. However, to explain these seemingly simple phenomena on the basis of fundamental principles of physics it was possible only relatively recently. There are two different types of magnets. Some are the so-called permanent magnets made from "magnetically hard" materials. Their magnetic properties not related to use external sources or currents. Another type is the so-called electromagnets with a "soft magnetic" iron core. The magnetic fields they create are mainly due to the fact that an electric current passes through the winding wire that surrounds the core.
Magnetic poles and magnetic field. The magnetic properties of a bar magnet are most noticeable near its ends. If such a magnet is suspended by the middle part so that it can freely rotate in the horizontal plane, then it will take a position approximately corresponding to the direction from north to south. The end of the bar pointing north is called the north pole, and the opposite end is called the south pole. The opposite poles of two magnets are attracted to each other, and the like poles are mutually repelled. If a bar of non-magnetized iron is brought closer to one of the poles of the magnet, the latter will be temporarily magnetized. In this case, the pole of the magnetized bar closest to the pole of the magnet will be opposite in name, and the far pole will be of the same name. The attraction between the pole of the magnet and the opposite pole induced by it in the bar and explains the action of the magnet. Some materials (such as steel) themselves become weak permanent magnets after being near a permanent magnet or electromagnet. A steel bar can be magnetized by simply sliding the end of the bar permanent magnet along its end. So, a magnet attracts other magnets and objects made of magnetic materials without being in contact with them. This action at a distance is explained by the existence of a magnetic field in the space around the magnet. Some idea of ​​the intensity and direction of this magnetic field can be obtained by sprinkling iron filings on a sheet of cardboard or glass placed on a magnet. The sawdust will line up in chains in the direction of the field, and the density of the sawdust lines will correspond to the intensity of this field. (They are thickest at the ends of the magnet, where the intensity of the magnetic field is greatest.) M. Faraday (1791-1867) introduced the concept of closed induction lines for magnets. The induction lines exit into the surrounding space from the magnet at its north pole, enter the magnet at the south pole, and pass through the magnet material from the south pole back to the north, forming a closed loop. Full number lines of induction emerging from a magnet is called magnetic flux. The magnetic flux density, or magnetic induction (B), is equal to the number of induction lines passing along the normal through an elementary area of ​​a unit value. Magnetic induction determines the force with which a magnetic field acts on a current conductor located in it. If the conductor through which the current I passes is perpendicular to the induction lines, then, according to Ampere's law, the force F acting on the conductor is perpendicular to both the field and the conductor and is proportional to the magnetic induction, current strength and the length of the conductor. Thus, for the magnetic induction B, you can write the expression

Where F is force in newtons, I is current in amperes, l is length in meters. The unit of measurement for magnetic induction is Tesla (T)
(see also ELECTRICITY AND MAGNETISM).
Galvanometer. The galvanometer is a sensitive instrument for measuring weak currents. The galvanometer uses the torque generated by the interaction of a horseshoe-shaped permanent magnet with a small current-carrying coil (weak electromagnet) suspended in the gap between the poles of the magnet. The torque, and therefore the deflection of the coil, is proportional to the current and the total magnetic induction in the air gap, so that the scale of the device is almost linear with small deflections of the coil. Magnetizing force and magnetic field strength. Next, you should introduce another value that characterizes the magnetic effect of an electric current. Suppose a current flows through the wire of a long coil that contains the material to be magnetized. The magnetizing force is the product of the electric current in the coil by the number of its turns (this force is measured in amperes, since the number of turns is a dimensionless quantity). The strength of the magnetic field H is equal to the magnetizing force per unit length of the coil. Thus, the value of H is measured in amperes per meter; it determines the magnetization acquired by the material inside the coil. In a vacuum, the magnetic induction B is proportional to the strength of the magnetic field H:

Where m0 is the so-called. magnetic constant with a universal value of 4pЧ10-7 H / m. In many materials, the value of B is approximately proportional to H. However, in ferromagnetic materials, the relationship between B and H is somewhat more complicated (which will be discussed below). In fig. 1 shows a simple electromagnet for gripping loads. The energy source is a DC rechargeable battery. The figure also shows the lines of force of the field of the electromagnet, which can be detected by the usual method of iron filings.

Large electromagnets with iron cores and very a large number ampere-turns, operating in continuous mode, have a large magnetizing force. They create a magnetic induction of up to 6 T between the poles; this induction is limited only by mechanical stresses, heating of the coils and magnetic saturation of the core. A number of giant electromagnets (without a core) with water cooling, as well as installations for creating pulsed magnetic fields, were designed by P.L. Kapitsa (1894-1984) in Cambridge and at the Institute of Physical Problems of the USSR Academy of Sciences and F. Bitter (1902-1967) in Massachusetts Institute of Technology. On such magnets, it was possible to achieve an induction of up to 50 T. A relatively small electromagnet, generating fields up to 6.2 T, consuming 15 kW of electrical power and cooled by liquid hydrogen, was developed at the Losalamos National Laboratory. Such fields are obtained at cryogenic temperatures.
Magnetic permeability and its role in magnetism. Permeability m is a quantity that characterizes the magnetic properties of a material. Ferromagnetic metals Fe, Ni, Co and their alloys have very high maximum permeabilities - from 5000 (for Fe) to 800,000 (for supermalloy). In such materials, at relatively low field strengths H, large inductions B appear, but the relationship between these quantities is, generally speaking, nonlinear due to the phenomena of saturation and hysteresis, which are discussed below. Ferromagnetic materials are strongly attracted by magnets. They lose their magnetic properties at temperatures above the Curie point (770 ° C for Fe, 358 ° C for Ni, 1120 ° C for Co) and behave like paramagnets, for which the induction B, up to very high values ​​of the intensity H, is proportional to it - in exactly the same as in a vacuum. Many elements and compounds are paramagnetic at all temperatures. Paramagnetic substances are characterized by the fact that they are magnetized in an external magnetic field; if this field is turned off, paramagnets return to a non-magnetized state. Magnetization in ferromagnets is retained even after the external field is turned off. In fig. 2 shows a typical hysteresis loop for a magnetically hard (high loss) ferromagnetic material. It characterizes the ambiguous dependence of the magnetization of a magnetically ordered material on the intensity of the magnetizing field. With an increase in the magnetic field strength from the initial (zero) point (1), the magnetization proceeds along the dashed line 1-2, and the value of m changes significantly as the magnetization of the sample increases. Saturation is reached at point 2, i.e. with a further increase in the tension, the magnetization no longer increases. If now gradually decrease the value of H to zero, then the curve B (H) no longer follows the previous path, but passes through point 3, revealing, as it were, the "memory" of the material about the "past history", hence the name "hysteresis". Obviously, in this case, some residual magnetization remains (section 1-3). After changing the direction of the magnetizing field to the opposite, the curve B (H) passes point 4, and the segment (1) - (4) corresponds to the coercive force that prevents demagnetization. A further increase in the (-H) values ​​brings the hysteresis curve into the third quadrant - section 4-5. A subsequent decrease in the value (-H) to zero and then an increase in positive values ​​of H will lead to the closure of the hysteresis loop through points 6, 7 and 2.

Magnetically hard materials are characterized by a wide hysteresis loop covering a large area in the diagram and therefore corresponding to large values ​​of remanent magnetization (magnetic induction) and coercive force. A narrow hysteresis loop (Fig. 3) is characteristic of soft magnetic materials such as mild steel and special alloys with high magnetic permeability. Such alloys were created with the aim of reducing energy losses due to hysteresis. Most of these special alloys, like ferrites, have high electrical resistance, which reduces not only magnetic losses, but also electrical ones caused by eddy currents.

Magnetic materials with high permeability are manufactured by annealing carried out by holding at a temperature of about 1000 ° C, followed by tempering (gradual cooling) to room temperature. At the same time, preliminary mechanical and thermal treatment, as well as the absence of impurities in the sample, are very important. For transformer cores at the beginning of the 20th century. Silicon steels were developed, the value of m of which increased with increasing silicon content. Between 1915 and 1920, permalloy (Ni-Fe alloys) with a characteristic narrow and almost rectangular hysteresis loop appeared. Hypernik (50% Ni, 50% Fe) and mu-metal (75% Ni, 18% Fe, 5% Cu, 2% Cr) alloys are distinguished by especially high values ​​of the magnetic permeability m at low values ​​of H, while in Perminvar (45 % Ni, 30% Fe, 25% Co), the value of m is practically constant over a wide range of changes in the field strength. Among modern magnetic materials, we should mention supermalla - an alloy with the highest magnetic permeability (it contains 79% Ni, 15% Fe and 5% Mo).
Theories of magnetism. For the first time, the idea that magnetic phenomena ultimately boil down to electrical, arose in Ampere in 1825, when he expressed the idea of ​​closed internal microcurrents circulating in each atom of a magnet. However, without any experimental confirmation of the presence of such currents in matter (the electron was discovered by J. Thomson only in 1897, and the description of the structure of the atom was given by Rutherford and Bohr in 1913), this theory "faded". In 1852 W. Weber suggested that each atom of a magnetic substance is a tiny magnet, or a magnetic dipole, so that the complete magnetization of the substance is achieved when all the individual atomic magnets are arranged in a certain order (Fig. 4, b). Weber believed that molecular or atomic "friction" helps these elementary magnets to maintain their order in spite of the disturbing influence of thermal vibrations. His theory was able to explain the magnetization of bodies in contact with a magnet, as well as their demagnetization upon impact or heating; finally, the "multiplication" of magnets was also explained when a magnetized needle or magnetic rod was cut into pieces. Yet this theory did not explain either the origin of the elementary magnets themselves, or the phenomena of saturation and hysteresis. Weber's theory was refined in 1890 by J. Ewing, who replaced his hypothesis of atomic friction with the idea of ​​interatomic limiting forces that help maintain the ordering of the elementary dipoles that make up a permanent magnet.

The approach to the problem, once proposed by Ampere, was given a second life in 1905, when P. Langevin explained the behavior of paramagnetic materials, attributing to each atom an internal uncompensated electron current. According to Langevin, it is these currents that form tiny magnets, randomly oriented when there is no external field, but acquiring an ordered orientation after it is applied. In this case, the approach to complete ordering corresponds to saturation of the magnetization. In addition, Langevin introduced the concept of a magnetic moment, equal for an individual atomic magnet to the product of the "magnetic charge" of a pole by the distance between the poles. Thus, the weak magnetism of paramagnetic materials is due to the total magnetic moment created by uncompensated electron currents. In 1907 P. Weiss introduced the concept of "domain", which became an important contribution to the modern theory of magnetism. Weiss imagined domains in the form of small "colonies" of atoms, within which the magnetic moments of all atoms, for some reason, are forced to maintain the same orientation, so that each domain is magnetized to saturation. A separate domain can have linear dimensions of the order of 0.01 mm and, accordingly, the volume of the order of 10-6 mm3. Domains are separated by so-called Bloch walls, the thickness of which does not exceed 1000 atomic dimensions. The "wall" and two oppositely oriented domains are schematically shown in Fig. 5. Such walls are "transition layers" in which the direction of the domain magnetization changes.

In general, three sections can be distinguished on the curve of the initial magnetization (Fig. 6). In the initial section, the wall under the action of an external field moves through the thickness of the substance until it encounters a defect in the crystal lattice, which stops it. By increasing the field strength, you can force the wall to move further, through the middle section between the dashed lines. If the field strength is then reduced to zero again, the walls will no longer return to their original position, so that the sample will remain partially magnetized. This explains the hysteresis of the magnet. At the end of the curve, the process ends with the saturation of the magnetization of the sample due to the ordering of the magnetization inside the last disordered domains. This process is almost completely reversible. Magnetic hardness is manifested by those materials in which the atomic lattice contains many defects that impede the movement of interdomain walls. This can be achieved by mechanical and thermal treatment, for example by compression and subsequent sintering of the powdery material. In alnico alloys and their analogues, the same result is achieved by fusing metals into a complex structure.

In addition to paramagnetic and ferromagnetic materials, there are materials with so-called antiferromagnetic and ferrimagnetic properties. The difference between these types of magnetism is illustrated in Fig. 7. Based on the concept of domains, paramagnetism can be regarded as a phenomenon caused by the presence of small groups of magnetic dipoles in the material, in which individual dipoles interact very weakly with each other (or do not interact at all) and therefore, in the absence of an external field, assume only random orientations ( Fig. 7, a). In ferromagnetic materials, within each domain, there is a strong interaction between individual dipoles, leading to their ordered parallel alignment (Fig. 7, b). In antiferromagnetic materials, on the contrary, the interaction between individual dipoles leads to their antiparallel ordered alignment, so that the total magnetic moment of each domain is zero (Fig. 7c). Finally, in ferrimagnetic materials (for example, ferrites) there is both parallel and antiparallel ordering (Fig. 7d), which results in weak magnetism.

There are two convincing experimental confirmations of the existence of domains. The first of them is the so-called Barkhausen effect, the second is the powder figure method. In 1919, G. Barkhausen established that when an external field is applied to a sample of a ferromagnetic material, its magnetization changes in small discrete portions. From the point of view of the domain theory, this is nothing more than an abrupt advancement of the interdomain wall, which encounters individual defects that delay it on its way. This effect is usually detected with a coil in which a ferromagnetic rod or wire is placed. If a strong magnet is alternately brought to and removed from the sample, the sample will be magnetized and remagnetized. Sudden changes in the magnetization of the sample change the magnetic flux through the coil, and an induction current is excited in it. The voltage generated in this coil is amplified and fed to the input of a pair of acoustic headphones. Clicks heard through the headphones indicate an abrupt change in magnetization. To reveal the domain structure of a magnet by the method of powder figures, a drop of a colloidal suspension of a ferromagnetic powder (usually Fe3O4) is applied to a well-polished surface of a magnetized material. Powder particles are deposited mainly in places of maximum inhomogeneity of the magnetic field - at the boundaries of domains. This structure can be studied under a microscope. A method was also proposed based on the transmission of polarized light through a transparent ferromagnetic material. The original Weiss theory of magnetism in its basic features has retained its significance to the present time, having received, however, an updated interpretation based on the concept of uncompensated electron spins as a factor determining atomic magnetism. The hypothesis of the existence of an intrinsic moment of the electron was put forward in 1926 by S. Goudsmit and J. Uhlenbeck, and at present it is electrons as spin carriers that are considered as "elementary magnets". To clarify this concept, consider (Fig. 8) a free iron atom - a typical ferromagnetic material. Its two shells (K and L), closest to the nucleus, are filled with electrons, and the first of them contains two, and the second - eight electrons. In the K shell, the spin of one of the electrons is positive and the other is negative. In the L-shell (more precisely, in its two subshells), four of the eight electrons have positive spins, and the other four have negative spins. In both cases, the spins of electrons within one shell are completely compensated, so that the total magnetic moment is zero. In the M-shell, the situation is different, since out of six electrons in the third subshell, five electrons have spins directed in one direction, and only the sixth in the other. As a result, four uncompensated spins remain, which determines the magnetic properties of the iron atom. (There are only two valence electrons in the outer N-shell, which do not contribute to the magnetism of the iron atom.) The magnetism of other ferromagnets, such as nickel and cobalt, is explained in a similar way. Since the neighboring atoms in the iron sample strongly interact with each other, and their electrons are partially collectivized, this explanation should be considered only as an illustrative, but very simplified diagram of the real situation.

The theory of atomic magnetism, based on taking into account the electron spin, is supported by two interesting gyromagnetic experiments, one of which was carried out by A. Einstein and W. de Haas, and the other by S. Barnett. In the first of these experiments, a cylinder made of a ferromagnetic material was suspended as shown in Fig. 9. If a current is passed through the winding wire, the cylinder rotates around its axis. When the direction of the current (and hence the magnetic field) changes, it turns in the opposite direction. In both cases, the rotation of the cylinder is due to the ordering of the electron spins. In Barnett's experiment, on the contrary, a suspended cylinder, sharply brought into rotation, is magnetized in the absence of a magnetic field. This effect is explained by the fact that when the magnet rotates, a gyroscopic moment is created, which tends to rotate the spin moments in the direction of its own axis of rotation.

For a more complete explanation of the nature and origin of short-range forces that order neighboring atomic magnets and counteract the disordering effects of thermal motion, one should turn to quantum mechanics. A quantum-mechanical explanation of the nature of these forces was proposed in 1928 by W. Heisenberg, who postulated the existence of exchange interactions between neighboring atoms. Later, G. Bethe and J. Slater showed that exchange forces significantly increase with decreasing distance between atoms, but after reaching a certain minimum interatomic distance, they fall to zero.
MAGNETIC PROPERTIES OF THE SUBSTANCE
One of the first extensive and systematic studies of the magnetic properties of matter was undertaken by P. Curie. He found that according to their magnetic properties, all substances can be divided into three classes. The first includes substances with pronounced magnetic properties, similar properties gland. Such substances are called ferromagnetic; their magnetic field is noticeable at considerable distances (see above). The second class includes substances called paramagnetic; their magnetic properties are generally similar to those of ferromagnetic materials, but much weaker. For example, the force of attraction to the poles of a powerful electromagnet can snatch an iron hammer out of your hands, and to detect the attraction of a paramagnetic substance to the same magnet, you usually need a very sensitive analytical balance. The last, third class includes the so-called diamagnetic substances. They are repelled by an electromagnet, i.e. the force acting on diamagnets is directed opposite to that which acts on ferro- and paramagnets.
Measurement of magnetic properties. In the study of magnetic properties, measurements of two types are most important. The first is to measure the force acting on the sample near the magnet; this is how the magnetization of the sample is determined. The second includes measurements of "resonant" frequencies associated with the magnetization of a substance. Atoms are tiny "gyroscopes" and precess in a magnetic field (like an ordinary top under the influence of a torque, created by force severity) with a frequency that can be measured. In addition, a force acts on free charged particles moving at right angles to the lines of magnetic induction, as well as on the electron current in a conductor. It makes the particle move in a circular orbit, the radius of which is given by the expression R = mv / eB, where m is the mass of the particle, v is its velocity, e is its charge, and B is the magnetic induction of the field. The frequency of such a circular motion is

where f is measured in hertz, e in pendants, m in kilograms, B in teslas. This frequency characterizes the movement of charged particles in a substance in a magnetic field. Both types of motion (precession and motion in circular orbits) can be excited by alternating fields with resonant frequencies equal to the "natural" frequencies characteristic of a given material. In the first case, the resonance is called magnetic, and in the second, it is called cyclotron (due to the similarity with the cyclic motion of a subatomic particle in a cyclotron). Speaking about the magnetic properties of atoms, it is necessary to pay special attention to their angular momentum. A magnetic field acts on a rotating atomic dipole, trying to rotate it and set it parallel to the field. Instead, the atom begins to precess around the direction of the field (Fig. 10) with a frequency that depends on the dipole moment and the strength of the applied field.

Atomic precession is not directly observable, since all atoms of the sample precess in different phase... If we apply a small alternating field directed perpendicular to the constant ordering field, then a certain phase relationship is established between the precessing atoms and their total magnetic moment begins to precess with a frequency equal to the precession frequency of individual magnetic moments. The angular velocity of the precession is of great importance. As a rule, this is a value of the order of 1010 Hz / T for magnetization associated with electrons, and of the order of 107 Hz / T for magnetization associated with positive charges in the nuclei of atoms. A schematic diagram of a facility for observing nuclear magnetic resonance (NMR) is shown in Fig. 11. The substance under study is introduced into a uniform constant field between the poles. If then, with the help of a small coil covering the test tube, a radio-frequency field is excited, then resonance can be achieved at a certain frequency equal to the precession frequency of all nuclear "gyroscopes" in the sample. The measurements are similar to tuning a radio receiver to the frequency of a particular station.

Magnetic resonance methods make it possible to investigate not only the magnetic properties of specific atoms and nuclei, but also the properties of their environment. The point is that magnetic fields in solids and molecules are inhomogeneous, since they are distorted by atomic charges, and the details of the experimental resonance curve are determined by the local field in the region where the precessing nucleus is located. This makes it possible to study the features of the structure of a particular sample by resonance methods.
Calculation of magnetic properties. The magnetic induction of the Earth's field is 0.5 * 10 -4 T, while the field between the poles of a strong electromagnet is about 2 T or more. The magnetic field created by any configuration of currents can be calculated using the Biot-Savart-Laplace formula for the magnetic induction of the field created by the current element. The calculation of the field generated by contours of different shapes and cylindrical coils is very complicated in many cases. Below are formulas for a number of simple cases. The magnetic induction (in teslas) of the field created by a long straight wire with a current I (ampere) at a distance r (meters) from the wire is

Induction in the center of a circular loop of radius R with current I is (in the same units):

A tightly wound coil of wire without an iron core is called a solenoid. The magnetic induction created by a long solenoid with the number of turns N at a point far enough from its ends is

Here, NI / L is the number of amperes (ampere-turns) per unit length of the solenoid. In all cases, the magnetic field of the current is directed perpendicular to this current, and the force acting on the current in the magnetic field is perpendicular to both the current and the magnetic field. The field of a magnetized iron rod is similar to the external field of a long solenoid with the number of ampere-turns per unit length corresponding to the current in atoms on the surface of the magnetized rod, since the currents inside the rod are mutually compensated (Fig. 12). By the name of Ampere, such a surface current is called Ampere. The intensity of the magnetic field Ha, created by the Ampere current, is equal to the magnetic moment of a unit volume of the rod M.

If an iron rod is inserted into the solenoid, then, in addition to the fact that the solenoid current creates a magnetic field H, the ordering of atomic dipoles in the magnetized material of the rod creates magnetization M. In this case, the total magnetic flux is determined by the sum of the real and Ampere currents, so that B = m0 (H + Ha), or B = m0 (H + M). The M / H ratio is called magnetic susceptibility and is denoted by the Greek letter c; c is a dimensionless quantity characterizing the ability of a material to magnetize in a magnetic field.
B / H value characterizing magnetic properties
material is called magnetic permeability and is denoted by ma, and ma = m0m, where ma is absolute, and m is relative permeability, m = 1 + c. In ferromagnetic substances the value of c can have very large values ​​- up to 10 4-10 6. The value of c for paramagnetic materials is slightly greater than zero, and for diamagnetic materials it is slightly less. Only in a vacuum and in very weak fields are the values ​​of c and m constant and independent of the external field. The dependence of induction B on H is usually nonlinear, and its graphs, the so-called. magnetization curves, for different materials and even with different temperatures can differ significantly (examples of such curves are shown in Figs. 2 and 3). The magnetic properties of matter are very complex, and their deep understanding requires a thorough analysis of the structure of atoms, their interactions in molecules, their collisions in gases and their mutual influence in solids and liquids; the magnetic properties of liquids are still the least studied. - fields with an intensity of H? 0.5 = 1.0 ME (the boundary is conditional). The lower value of S. m. Of the item corresponds to the max. the value of the stationary field = 500 kOe, which may be available to the means of modern techniques, the upper field of 1 ME, even for a short time. impact to the horn ... ... Physical encyclopedia

A branch of physics that studies the structure and properties of solids. Scientific data on the microstructure of solids and on the physical and chemical properties of their constituent atoms are necessary for the development of new materials and technical devices... Physics ... ... Collier's Encyclopedia

A branch of physics covering knowledge of static electricity, electric currents and magnetic phenomena. ELECTROSTATICS In electrostatics, the phenomena associated with resting electric charges are considered. The presence of forces acting between ... ... Collier's Encyclopedia

- (from ancient Greek physis nature). The ancients called physics any study of the surrounding world and natural phenomena. This understanding of the term physics survived until the end of the 17th century. Later, a number of special disciplines appeared: chemistry, which studies the properties ... ... Collier's Encyclopedia

The term moment in relation to atoms and atomic nuclei can mean the following: 1) spin moment, or spin, 2) magnetic dipole moment, 3) electric quadrupole moment, 4) other electric and magnetic moments. Various types… … Collier's Encyclopedia

An electrical analogue of ferromagnetism. Just as in ferromagnetic substances, when placed in a magnetic field, residual magnetic polarization (moment) appears, in ferroelectric dielectrics placed in an electric field ... ... Collier's Encyclopedia

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Magnet

Magnets, such as the toys stuck to your home refrigerator or the horseshoes you were shown at school, have a few unusual features. First of all, magnets are attracted to iron and steel objects, such as a refrigerator door. They also have poles.

Bring two magnets closer to each other. The south pole of one magnet will be attracted to the north pole of another. The north pole of one magnet repels the north pole of the other.

Magnetic and electric current

The magnetic field is generated by an electric current, that is, moving electrons. Electrons moving around atomic nucleus are negatively charged. The directed movement of charges from one place to another is called electric current. The electric current forms a magnetic field around itself.

This field, with its lines of force, like a loop, covers the path of an electric current, like an arch that stands over a road. For example, when a desk lamp is turned on and a current flows through the copper wires, that is, the electrons in the wire jump from atom to atom and a weak magnetic field is created around the wire. High-voltage lines have a much stronger current than a table lamp, so a very strong magnetic field forms around the wires of these lines. Thus, electricity and magnetism are two sides of the same coin - electromagnetism.

Related materials:

Why do cats love to sleep in public?

Electron movement and magnetic field

The movement of electrons within each atom creates a tiny magnetic field around it. An orbiting electron forms a vortex-like magnetic field. But most of the magnetic field is created not by the motion of the electron in its orbit around the nucleus, but by the motion of the atom around its axis, the so-called electron spin. Spin characterizes the rotation of an electron around an axis, as the movement of a planet around its axis.

Why materials magnet and not magnet

In most materials, such as plastics, the magnetic fields of individual atoms are randomly oriented and mutually quench each other. But in materials like iron, atoms can be oriented so that their magnetic fields add up, so the piece of steel becomes magnetized. The atoms in materials are linked into groups called magnetic domains. The magnetic fields of one separate domain are oriented in one direction. That is, each domain is a small magnet.

It is difficult to find such an area in which there would be no application for magnets. Educational toys, useful accessories and sophisticated industrial equipment are just a fraction of the truly huge number of options for their use. At the same time, few people know how magnets are arranged and what is the secret of their attraction force. To answer these questions, you need to dive into the basics of physics, but don't worry - the dive will be short-lived and shallow. But after getting acquainted with the theory, you will learn what a magnet consists of, and the nature of its magnetic force will become much clearer for you.

The electron is the smallest and simplest magnet

Any substance consists of atoms, and atoms, in turn, consist of a nucleus, around which positively and negatively charged particles - protons and electrons - revolve. The subject of our interest is precisely the electrons. Their movement creates an electric current in the conductors. In addition, each electron is a miniature source of a magnetic field and, in fact, is the simplest magnet. However, in the composition of most materials, the direction of movement of these particles is chaotic. As a result, their charges balance each other. And when the direction of rotation of a large number of electrons in their orbits coincides, then a constant magnetic force arises.

Magnet device

So, we figured out the electrons. And now we are very close to answering the question of how magnets work. In order for the material to attract the iron piece of rock, the direction of the electrons in its structure must coincide. In this case, the atoms form ordered regions called domains. Each domain has a pair of poles: north and south. A constant line of movement of magnetic forces passes through them. They enter the south pole and exit the north pole. Such a device means that the north pole will always attract the south pole of another magnet, while the poles of the same name will repel.

How a magnet attracts metals

Not all substances are affected by the magnetic force. Only a few materials can be attracted: iron, nickel, cobalt and rare earth metals... An iron piece of rock is not a natural magnet, but when exposed to a magnetic field, its structure is rearranged into domains with northern and south poles... Thus, the steel can be magnetized and retain its changed structure for a long time.

How magnets are made

We have already figured out what a magnet consists of. It is a material in which the directionality of the domains is the same. A strong magnetic field or electric current can be used to impart these properties to the rock. At the moment, people have learned how to make very powerful magnets, the force of attraction of which is tens of times greater than its own weight and persists for hundreds of years. It is about rare earth supermagnets based on neodymium alloy. Such items weighing 2-3 kg can hold objects weighing 300 kg or more. What does a neodymium magnet consist of and what causes such amazing properties?

Plain steel is not suitable for successfully making products with the most powerful force attraction. This requires a special composition that will allow you to organize the domains as efficiently as possible and maintain the stability of the new structure. To understand what a neodymium magnet is made of, imagine a metal powder of neodymium, iron and boron, which using industrial installations will be magnetized by a strong field and sintered into a rigid structure. To protect this material, it is covered with a strong galvanized sheath. This production technology makes it possible to obtain products of various sizes and shapes. In the assortment of the World of Magnets online store you will find a huge variety of magnetic goods for work, entertainment and everyday life.

Our understanding of the basic structure of matter has evolved gradually. The atomic theory of the structure of matter has shown that not everything in the world is arranged as it seems at first glance, and that difficulties at one level are easily explained at the next level of detail. Throughout the twentieth century, after the discovery of the structure of the atom (that is, after the appearance of the Bohr model of the atom), the efforts of scientists were focused on solving the structure of the atomic nucleus.

Initially, it was assumed that there are only two types of particles in the atomic nucleus - neutrons and protons. However, starting in the 1930s, scientists increasingly began to obtain experimental results that were inexplicable within the framework of the classical Bohr model. This led scientists to the idea that in fact the core is dynamic system various particles, whose rapid formation, interaction and decay play a key role in nuclear processes. By the early 1950s, the study of these as they were called elementary particles had come to the forefront of physical science. "
elementy.ru/trefil/46
"The general theory of interactions is based on the principle of continuity.

The first step in creating general theory, was the materialization of the abstract principle of continuity to the real world that we observe around. As a result of such materialization, the author came to the conclusion about the existence of the internal structure of the physical vacuum. Vacuum is a space continuously filled with fundamental particles - bions - various movements, arrangements and associations of which are able to explain all the richness and diversity of nature and mind.

As a result, a new general theory was created, which, on the basis of one principle, and therefore, identical, consistent and logically connected visual (material), and not virtual particles, describes the phenomena of nature and the phenomena of the human mind.
The main thesis is the principle of continuity.

The principle of continuity means that not a single process actually existing in nature can start spontaneously and end without a trace. All processes that can be described by mathematical formulas can only be calculated using continuous dependencies or functions. All changes have their reasons, the speed of transmission of any interactions is determined by the properties of the environment in which objects interact. But these objects themselves, in turn, change the environment in which they are located and interact.
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Field is a set of elements for which arithmetic operations are defined. The field is also continuous - one element of the field passes into another smoothly, the border between them cannot be specified.

This definition of the field also follows from the principle of continuity. It (definition) requires a description of the element responsible for all kinds of fields and interactions.
In the general theory of interactions, in contrast to theories dominating on this moment, quantum mechanics and the theory of relativity, such an element is explicitly defined.
This element is bion. All space of the Universe and vacuum and particles are made of bions. Bion is an elementary dipole, that is, a particle consisting of two connected charges of the same size, but different in sign. The total charge of the bion is zero. The detailed device of the bion is shown on the page The structure of the physical vacuum.
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It is impossible to indicate the boundaries of the bion (an understandable analogy with the Earth's atmosphere, the boundary of which cannot be accurately determined), since all the transitions are very, very smooth. Therefore, there is practically no internal friction between the bions. However, the effect of such "friction" becomes noticeable at large distances, and we observe it as a redshift.
Electric field in the general theory of interactions.
The existence of an electric field in any area of ​​space will represent a zone of coherently located and in a certain way oriented bions.
b-i-o-n.ru/_mod_files/ce_image ...
Magnetic field in the general theory of interactions.
The magnetic field will represent a certain dynamic configuration of the location and movement of the bions.
b-i-o-n.ru/theory/elim/

An electric field is a region of space in which the physical vacuum has a certain ordered structure. In the presence of an electric field, the vacuum exerts a force on the test electric charge. This effect is due to the location of bions in this area of ​​space.
Unfortunately, we have not yet managed to penetrate into the secret of how an electric charge works. Otherwise, the following picture is obtained. Any charge, let it be negative for example, creates the next orientation of bions around itself - an electrostatic field.
The main part of the energy belongs to the charge, which has a certain size. And the energy of the electric field is the energy of the ordered arrangement of bions (every order has an energy basis). It is also clear how distant charges “feel” each other. These "sensitive organs" are bions oriented in a certain way. We also note one more important conclusion. The rate of establishment of the electric field is determined by the rate of rotation of the bions so that they become oriented in relation to the charge as shown in the figure. And this explains why the speed of establishment of the electric field is equal to the speed of light: in both processes, the bions must transfer rotation to each other.
Taking the easy next step, we can confidently say that the magnetic field is the next dynamic configuration of bions.
b-i-o-n.ru/theory/elim

It is worth noting that the magnetic field does not manifest itself in any way until there are objects on which it can act (a compass needle or an electric charge).
Magnetic field superposition principle. The axes of rotation of bions occupy an intermediate position, depending on the direction and strength of the interacting fields.
The action of a magnetic field on a moving charge.
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The magnetic field does not act on a resting charge, because the rotating bions will create oscillations of such a charge, but we cannot detect such oscillations due to their smallness.

Surprisingly, in not a single textbook I did not find an answer, but even a question that should obviously arise in everyone who begins to study magnetic phenomena.
This is the question. Why does the magnetic moment of a circuit with a current do not depend on the shape of this circuit, but only on its area? I think that such a question is not asked precisely because no one knows the answer to it. When relying on our ideas, the answer is obvious. The magnetic field of the circuit is the sum of the magnetic fields of the bions. And the number of bions creating a magnetic field is determined by the area of ​​the circuit and does not depend on its shape. "
If you look more broadly, without going into theory, a magnet works by pulsing a magnetic field. Due to this pulsation, the orderliness of the movement of force particles arises total strength affecting objects of the environment. The impact is carried by a magnetic field, in which particles and quanta can also be released.
The theory of bions distinguishes bion as an elementary particle. You can see how fundamental it is.
The theory of space gravitons allocates a quantum of the entire universe graviton. And gives the fundamental laws governing the universe.
n-t.ru/tp/ns/tg.htm Space theory of gravitons
"The dialectics of the development of science consists in the quantitative accumulation of such abstract concepts (" demons ") describing more and more new laws of nature, which at a certain stage reaches a critical level of complexity. The resolution of such a crisis invariably requires a qualitative leap, a deep revision of basic concepts, removing" demonicity ”from accumulated abstractions, revealing their meaningful essence in the language of a new generalizing theory.
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TPG postulates the physical (actual) existence of a transitive space, the elements of which, within the framework of this theory, are called gravitons.
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Those. we assume that it is the physical space of gravitons (GG) that provides the universal interconnection of physical objects available to our knowledge, and is that minimum necessary substance, without which scientific knowledge is impossible in principle.
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TPG postulates discreteness and fundamental indivisibility of gravitons, their absence of any internal structure. Those. the graviton within the TPG acts as an absolute elementary particle, close in this sense to the atom of Democritus. In the mathematical sense, the graviton is an empty set (null-set).
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The main and only property of the graviton is its ability to copy itself, generating a new graviton. This property defines a strict imperfect order relation on the set PG: gi< gi+1, где gi – гравитон-родитель и gi+1 – дочерний гравитон, являющийся копией родителя. Это отношение интенсионально определяет ПГ как транзитивное и антирефлексивное множество, из чего следует также его асимметричность и антисимметричность.
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TPG postulates the continuity and limiting density of the PG, which fills the entire cognizable Universe in such a way that any physical object in this Universe can be associated with a non-empty subset of the PG, which uniquely determines the position of this object in the PG, and hence in the Universe.
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PG is a metric space. As a natural metric of GHG, we can choose minimal amount transitions from one neighboring graviton to another, necessary to close the transitive chain connecting a pair of gravitons, the distance between which we determine.
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The properties of the graviton allow us to talk about the quantum nature of this concept. Graviton is a quantum of motion, which is realized in the act of copying itself by graviton and "birth" of a new graviton. In a mathematical sense, this act can be associated with the addition of one to an already existing natural number.
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Another consequence of the proper motion of the PG are resonance phenomena that generate virtual elementary particles, in particular, the relic radiation photons.
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Using the basic concepts of TPG, we have built a physical model of space, which is not a passive repository of other physical objects, but itself actively changes and moves. Unfortunately, no conceivable devices will give us the opportunity to directly investigate the activity of GHGs, since gravitons penetrate all objects, interacting with the smallest elements of their internal structure. Nevertheless, we can obtain meaningful information about the motion of gravitons by examining the regularities and resonance phenomena of the so-called relict radiation, which is to the greatest extent determined by the activity of the GHG.
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The nature of gravitational interaction

“The fact that gravity should be an internal, integral and essential attribute of matter, thereby allowing any body to act on another at a distance through a vacuum, without any intermediary through which and through which action and force could be transmitted from one body to to another, it seems to me such a blatant absurdity that, in my deep conviction, not a single person, in any way experienced in philosophical matters and endowed with the ability to think, will agree with it. " (from Newton's letter to Richard Bentley).
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Within the framework of TPG, gravitation loses its force nature and is completely defined precisely as the regularity of the motion of physical objects that "bind" free gravitons with the entire volume of their internal structure, since gravitons freely penetrate any physical object, being integral elements of its internal structure. All physical objects "absorb" gravitons, distorting the isotropic proliferation of the PG, precisely due to this, rather close and massive space objects form compact clusters, having time to compensate for the expansion of the PG inside the cluster. But these clusters themselves, separated by such volumes of PGs, the proliferation of which they are unable to compensate, scatter the faster, the larger this volume of PGs separating them. Those. the same mechanism determines both the "attraction" effect and the effect of the scattering of galaxies.
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Let us now consider in more detail the mechanism of "absorption" of gravitons by physical objects. The intensity of such "absorption" essentially depends on the internal structure of objects and is determined by the presence of specific structures in this structure, as well as their number. The gravitational "absorption" of a free graviton is the simplest and weakest of such mechanisms, which does not require any special structures; a single graviton is involved in the act of such "absorption". Any other type of interaction uses the interaction particles corresponding to this type, defined on a certain subset of gravitons, therefore the efficiency of such interaction is much higher, in the act of interaction a lot of gravitons are "absorbed" together with a particle defined on them. Note also that in such interactions, one of the objects should play the same role as the PG in the gravitational interaction, i.e. it must generate more and more particles of a given interaction, using for such activity the very specific structures that we mentioned above. Thus, the general scheme of any interaction remains always the same, and the power of the interaction is determined by the "volume" of interaction particles and the activity of the source that generates them. "
One can understand magnetic interaction by the model of generation and absorption of elementary particles of a magnetic field. Moreover, the particles have different frequencies, and therefore the potential field is composed, consisting of the levels of intensity, the rainbow. Particles "float" on these levels. They can be absorbed by other particles, for example, ions of the crystal lattice of some metals, but the effect on them of the magnetic field will continue. The metal is attracted to the body of the magnet.
Superstring Theory, despite its name, provides a clear picture of the world. Better: it identifies many trajectories of interaction in the world.
ergeal.ru/other/superstrings.htm Superstring Theory (Dmitry Polyakov)
“So, the string is a kind of primary creation in the visible universe.

This object is not material, nevertheless, it can be imagined approximately in the form of some kind of stretched thread, rope or, for example, a violin string flying in ten-dimensional space-time.

Flying in ten dimensions, this extended object also experiences internal vibrations. It is from these vibrations (or octaves) that all matter originates (and, as it turns out later, not only matter). Those. all the variety of particles in nature are just different octaves of one total primordial creation - strings. A good example of two such different octaves emanating from a single string is gravity and light (gravitons and photons). Here, however, there are some subtleties - it is necessary to distinguish between the spectra of closed and open strings, but now these details have to be omitted.

So, how to study such an object, how do ten dimensions arise and how to find the correct compactification of ten dimensions to our four-dimensional world?

Unable to "catch" the string, we follow its tracks and explore its trajectory. Just as the trajectory of a point is a curved line, the trajectory of a one-dimensional extended object (string) is a two-dimensional SURFACE.

Thus, mathematically, string theory is the dynamics of two-dimensional random surfaces embedded in a higher-dimensional space.

Each such surface is called a WORLD SHEET.

In general, all kinds of symmetries play an extremely important role in the Universe.

From the symmetry of a particular physical model, it is often possible to draw the most important conclusions about its (model) dynamics, evolution, mutation, etc.

In String Theory, such a cornerstone symmetry is the so-called. REPARAMETRIZATION INVARIANCE (or "group of diffeomorphisms"). This invariance, speaking very roughly and approximately, means the following. Imagine mentally an observer who "sat down" on one of the world's sheets, "swept" by a string. In his hands is a flexible ruler, with the help of which he examines the geometric properties of the surface of the World List. So - the geometric properties of the surface, obviously, do not depend on the graduation of the ruler. The independence of the World List structure from the scale of the "mental ruler" is called Reparametrization Invariance (or R-invariance).

Despite its apparent simplicity, this principle leads to extremely important consequences. First of all, is it fair at the quantum level?
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Spirits are fields (waves, vibrations, particles), the probability of observing which is negative.

For a rationalist, this is, of course, absurd: after all, the classical probability of any event lies always between 0 (when the event will not happen for sure) and 1 (when, on the contrary, it will happen for sure).

The likelihood of the appearance of Spirits, however, is negative. This is one of the possible definitions of Spirits. Apophatic definition. In this regard, I recall the definition of Love by Abba Dorotheus: "God is the center of the circle. And people are radii. Having loved God, people approach the Center as radii. Having loved each other, they approach God as the center."

So, let's summarize the first results.

We met the Observer, who is put on the World List with a ruler. And the graduation of the ruler, at first glance, is arbitrary, and the World List is indifferent to this Arbitrariness.

This Indifference (or symmetry) is called Reparametrization Invariance (R-invariance, a group of diffeomorphisms).

The need to link Indifference with Uncertainty leads to the conclusion that the Universe is ten-dimensional.

In fact, everything is more complicated.

With any kind of ruler, and, of course, no one will let the observer on the World List. The ten-dimensional world is bright, strict and does not tolerate any ad-libbing. For any gag with the World Leaf, the bastard would have their ruler forever taken away and well carved like a Protestant.
^
But if the Observer is not a Protestant, he is given a Ruler once and for all determined, verified, unchanged for centuries, and with this strictly selected Single Ruler, he is admitted to the World List.

In Superstring Theory, this ritual is called "fixing the gauge."

As a result of fixing the calibration, the Faddeev-Popov Spirits appear.

It is these Spirits that give the Ruler to the Observer.

However, the choice of calibration is just a purely exoteric, police function of the Faddeev-Popov Spirits. The exoteric, advanced mission of these Spirits is to choose the correct compactification and, subsequently, to generate solitons and Chaos in the compactified world.

How exactly this happens is a very subtle question and is not completely clear; I will try to describe this process as briefly and clearly as possible, omitting technical details as much as possible.

All Superstring Theory reviews contain the so-called. The Absence of Spirits Theorem. This Theorem states that the Spirits, although they determine the choice of gauge, nevertheless, do not directly affect the vibrations of the string (the vibrations that generate matter) in any way. In other words, according to the theorem, the spectrum of a string does not contain Ghosts, i.e. The Space of Spirits is completely separated from the emanations of matter, and Spirits are nothing more than an artifact of fixing the calibration. We can say that these are Spirits - a consequence of the imperfection of the observer, in no way connected with the dynamics of the string. This is a classic result, in some cases more or less correct. However, the applicability of this theorem is limited, since all her known proofs do not take into account one extremely important nuance. This nuance is associated with the so-called. "breaking the symmetry of the pictures".
What it is? Consider an arbitrary vibration of a string: for example, an emanation of light (photon). It turns out there are several different ways descriptions of this emanation. Namely, in string theory, emanations are described using the so-called. "vertex operators". Each emanation corresponds to several supposedly equivalent vertex operators. These equivalent operators differ from each other in their "ghost numbers", i.e. structure of the Faddeev-Popov Spirits.

Each such equivalent description of the same emanation is called a Picture. There is a so-called. "conventional wisdom", which insists on the equivalence of Pictures, i.e. vertex operators with different ghost numbers. This assumption is known as "picture-changing symmetry of vertex operators".

This "conventional wisdom" is tacitly implied in the proof of the Absence Theorem. However, a closer analysis shows that this symmetry does not exist (more precisely, it exists in some cases and is broken in others). Because of the violation of the Symmetry of Pictures, the above Theorem is also violated in a number of cases. And this means that the Spirits play a direct role in the vibrations of the string, the spaces of matter and Spirits are not independent, but intertwined in the most subtle way.

The intersection of these spaces plays an important role in dynamic compactification and the formation of Chaos. "
A different vision of Superstring theory elementy.ru/trefil/21211
"Various versions of string theory are today considered as the main contenders for the title of an all-encompassing universal theory that explains the nature of everything. And this is a kind of Holy Grail of theoretical physicists dealing with the theory of elementary particles and cosmology. The universal theory (aka the theory of everything that exists) contains there are only a few equations that combine the entire body of human knowledge about the nature of interactions and the properties of the fundamental elements of matter from which the Universe is built.Today, string theory has been combined with the concept of supersymmetry, resulting in the birth of superstring theory, and today this is the maximum what was achieved in terms of combining the theory of all four basic interactions (forces acting in nature).
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For clarity, interacting particles can be considered "bricks" of the universe, and particles-carriers - cement.
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In the framework of the Standard Model, quarks act as bricks, and gauge bosons, which these quarks exchange with each other, act as carriers of interaction. The theory of supersymmetry goes even further and asserts that the quarks and leptons themselves are not fundamental: they all consist of even heavier and not experimentally discovered structures (bricks) of matter, held together by an even stronger "cement" of super-energetic particles-carriers of interactions than quarks composed of hadrons and bosons. Naturally, in laboratory conditions, none of the predictions of the theory of supersymmetry has yet been verified, however, hypothetical hidden components of the material world already have names - for example, a selectron (supersymmetric partner of an electron), squark, etc. kind is predicted unambiguously.
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The picture of the universe offered by these theories, however, is fairly easy to visualize. On a scale of the order of 10–35 m, that is, 20 orders of magnitude less than the diameter of the same proton, which includes three bound quarks, the structure of matter differs from the one we are accustomed to even at the level of elementary particles. At such small distances (and at such high interaction energies that this is unthinkable) matter turns into a series of standing field waves, similar to those that are excited in strings musical instruments... Like a guitar string, in such a string, in addition to the fundamental tone, many overtones or harmonics can be excited. Each harmonic has its own energy state. According to the principle of relativity (see Theory of Relativity), energy and mass are equivalent, which means that the higher the frequency of the harmonic wave vibration of the string, the higher its energy, and the higher the mass of the observed particle.

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

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

That, perhaps, is all that can be briefly told about one of the theories that, not without reason, claim today to be the universal theory of the Great Unification of all force interactions. "
ru.wikipedia.org/wiki/%D0%A2%D ... Superstring Theory.
A universal theory explaining all physical interactions: elementy.ru/trefil/21216
"There are four fundamental forces in nature, and all physical phenomena occur as a result of interactions between physical objects, which are caused by one or more of these forces. Four types of interactions in decreasing order of their strength are:

* strong interaction that keeps quarks in the composition of hadrons and nucleons in the composition of the atomic nucleus;
* electromagnetic interaction between electric charges and magnets;
* weak interaction, which causes some types of reactions radioactive decay; and
* gravitational interaction.

In the classical mechanics of Newton, any force is just a force of attraction or repulsion, causing a change in the nature of the movement of a physical body. In modern quantum theories, however, the concept of force (now interpreted as the interaction between elementary particles) is interpreted somewhat differently. Force interaction is now considered to be the result of a carrier particle exchange of interaction between two interacting particles. With this approach, the electromagnetic interaction between, for example, two electrons is due to the exchange of a photon between them, and in a similar way, the exchange of other mediating particles leads to the emergence of three other types of interactions. (See Standard Model for details.)

Moreover, the nature of the interaction is due to physical properties particles-carriers. In particular, Newton's law of universal gravitation and Coulomb's law have the same mathematical formulation precisely because in both cases, the carriers of interaction are particles devoid of rest mass. Weak interactions manifest themselves only at extremely small distances (in fact, only inside the atomic nucleus), since their carriers - gauge bosons - are very heavy particles. Strong interactions also manifest themselves only at microscopic distances, but for a different reason: here the whole thing is in the "trapping of quarks" inside hadrons and fermions (see the Standard Model).

The optimistic labels “universal theory”, “theory of all things,” “grand unification theory,” “ultimate theory” are used today for any theory that tries to unify all four interactions, considering them as different manifestations of some one and great force. If this succeeded, the picture of the structure of the world would be simplified to the limit. All matter would consist only of quarks and leptons (see the Standard Model), and forces of the same nature would act between all these particles. The equations describing the basic interactions between them would be so short and clear that they would fit on a postcard, while describing, in fact, the basis of all processes observed in the Universe without exception. According to the Nobel laureate, American theoretical physicist Steven Weinberg (Steven Weinberg, 1933–1996), "it would be a deep theory, from which the interference picture of the structure of the universe diverged like arrows in all directions, and deeper theoretical foundations would not be required in the future." As can be seen from the continuous subjunctive moods in the quotation, such a theory still does not exist. All that remains for us is to outline the approximate outlines of the process that could lead to the development of such a comprehensive theory.
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All unification theories proceed from the fact that at sufficiently high energies of interaction between particles (when they have a speed close to the limiting speed of light), "ice melts", the line between different types of interactions is erased, and all forces begin to act in the same way. At the same time, theories predict that this does not happen simultaneously for all four forces, but in stages, as the interaction energies increase.

The lowest energy threshold at which the first fusion of forces of different types can occur is extremely high, but it is already within the reach of the most modern accelerators. The energies of particles in the early stages of the Big Bang were extremely high (see also Early Universe). In the first 10–10 s, they ensured the unification of weak nuclear and electromagnetic forces into an electroweak interaction. Only from that moment on, all four forces known to us were finally divided. Until this moment, there were only three fundamental forces: strong, electroweak and gravitational interactions.
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The next unification occurs at energies far beyond those achievable in the conditions of terrestrial laboratories - they existed in the Universe in the first 10e (–35) c of its existence. Starting from these energies, the electroweak interaction is combined with the strong one. The theories describing the process of such a merger are called grand unification theories (MSW). It is impossible to test them on experimental installations, but they predict well the course of a number of processes occurring at lower energies, and this serves as an indirect confirmation of their truth. However, at the MSW level, our possibilities in terms of testing universal theories are being exhausted. Next, the field of superunification theories (TCO) or general theories begins - and at the mere mention of them, a shine in the eyes of theoretical physicists begins. A consistent TCO would allow to combine gravity with a single strong-electroweak interaction, and the structure of the Universe would receive the simplest possible explanation. "
The search for laws and formulas explaining all physical phenomena is noted. This search encompasses micro-level processes and macro-level ones. They differ in the strength or energy that is exchanged.
Interaction at the level of a magnetic field is described by electromagnetism.

"Electromagnetism*

The beginning of the doctrine of electromagnetic phenomena was laid by the discovery of Oersted. In 1820, Oersted showed that a wire through which an electric current flows causes a deflection of a magnetic needle. He examined this deviation in detail from the qualitative point of view, but did not give a general rule by which it would be possible to determine the direction of the deviation in each individual case. Following Oersted, discoveries followed one another. Ampere (1820) published his works on the action of current on current or current on a magnet. Ampere owns a general rule for the action of current on a magnetic needle: if you imagine yourself located in a conductor facing the magnetic needle and, moreover, so that the current has a direction from the legs to the head, then the north pole deviates to the left. Further we will see that Ampere reduced electromagnetic phenomena to electrodynamic phenomena (1823). The works of Arago also date back to 1820, who noticed that a wire through which an electric current flows attracts iron filings. He also magnetized for the first time iron and steel wires, placing them inside a coil of copper wires through which the current passed. He also managed to magnetize the needle by placing it in a coil and discharging the Leyden jar through the coil. Independently of Arago, the magnetization of steel and iron by current was discovered by Davy.

The first quantitative definitions of the effect of a current on a magnet in the same way date back to 1820 and belong to Biot and Savard.
If we fix a small magnetic needle sn near a long vertical conductor AB and astasize the earth's field with a magnet NS (Fig. 1), then we can find the following:

1. When current passes through the conductor, the magnetic needle is set with its length at right angles to the perpendicular dropped from the center of the arrow onto the conductor.

2. The force acting on one or the other pole n and s is perpendicular to the plane drawn through the conductor and this pole

3. The force with which a given current acts on the magnetic needle, passing through a very long straight conductor, is inversely proportional to the distance from the conductor to the magnetic needle.

All these observations and others can be deduced from the following elementary quantitative law, known as the Laplace-Bio-Savart law:

dF = k (imSin θ ds) / r2, (1),

where dF is the action of the current element on the magnetic pole; i is the current strength; m is the amount of magnetism, θ is the angle made by the direction of the current in the element with the line connecting the pole with the current element; ds is the length of the current element; r is the distance of the considered element from the pole; k - coefficient of proportionality.

Based on the law, action is equal to reaction, Ampere concluded that the magnetic pole should act on an element of current with the same strength

dФ = k (imSin θ ds) / r2, (2)

directly opposite in direction to the force dF, which also acts in a direction making a right angle with the plane passing through the pole and the given element. Although expressions (1) and (2) are in good agreement with experiments, nevertheless they have to be viewed not as a law of nature, but as a convenient means of describing the quantitative side of processes. main reason this is in the fact that we do not know any currents, except for closed ones, and, therefore, the assumption of a current element is essentially wrong. Further, if we add to expressions (1) and (2) some functions limited only by the condition that their integral over a closed loop is equal to zero, then the agreement with experiments will be no less complete.

All the above facts lead to the conclusion that the electric current causes a magnetic field around itself. For the magnetic force of this field, all laws that are valid for a magnetic field in general must be true. In particular, it is quite appropriate to introduce the concept of lines of force of a magnetic field caused by an electric current. The direction of the lines of force in this case can be detected in the usual way by means of iron filings. If you pass a vertical wire with a current through a horizontal sheet of cardboard and sprinkle sawdust on the cardboard, then with a slight tap, the sawdust will be arranged in concentric circles, if only the conductor is long enough.
Since the lines of force close around the wire and since the line of force determines the path along which the unit of magnetism would move in a given field, it is clear that it is possible to cause the rotation of the magnetic pole around the current. The first device in which such a rotation was carried out was built by Faraday. Obviously, the strength of the magnetic field can be used to judge the strength of the current. We will now approach this issue.

Considering the magnetic potential of a very long straight current, we can easily prove that this potential is multivalued. At a given point, he can have infinitely big number different values ​​differing from one another by 4 kmi π, where k is a coefficient, the rest of the letters are known. This explains the possibility of continuous rotation of the magnetic pole around the current. 4 kmi π is the work done during one revolution of the pole; it is taken from the energy of the current source. Of particular interest is the case of a closed current. We can imagine a closed current in the form of a loop made on a wire through which current flows. The loop has an arbitrary shape. The two ends of the loop are folded into a bundle (cord) and go to a far-delivered element.