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Already in the ancient world, thinkers thought about the nature and essence of space and time. Some of the philosophers denied the possibility of the existence of an empty space or, as they put it, non-existence. These were representatives of the Eleatic school in ancient Greece - Parmenides and Zeno. Other philosophers, including Democritus, argued that the void exists, like atoms, and is necessary for their movements and connections.
Until the 16th century, the geocentric system of Ptolemy dominated in natural science. It was the first universal mathematical model of the world, in which time was infinite, and space was finite, including the uniform circular motion of celestial bodies around the motionless Earth. A radical change in the spatial and entire physical picture occurred in the heliocentric system of the world, represented by Copernicus. Recognizing the mobility of the Earth, he rejected all pre-existing ideas about its uniqueness as the center of the Universe and thereby directed the movement of scientific thought towards the recognition of the infinity and infinity of space. This idea has been developed in the philosophy Giordano Bruno, who concluded that the universe is infinite and has no center.
An important role in the development of ideas about space was played by open Galileo the principle of inertia. According to this principle, all physical (mechanical) phenomena occur in the same way in all systems moving uniformly and rectilinearly with a speed constant in magnitude and direction.
Further development of the concept of space and time is associated with the physical and cosmic picture of the world R. Descartes. He based it on the idea that all natural phenomena are explained by the mechanical action of elementary material particles. The very same impact Descartes represented in the form of pressure or impact when particles come into contact with each other and thus introduced into physics the idea close range.
A new physical picture of the world was presented in classical mechanics I. Newton. He drew a harmonious picture of the planetary system, gave a rigorous quantitative theory of planetary motion. The pinnacle of his mechanics was the theory of gravity, which proclaimed the universal law of nature - law of gravity. According to this law, any two bodies attract each other with a force that is directly proportional to their masses and inversely proportional to the square of the distance between them.
This law is expressed by the following formula:
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This law says nothing about the dependence of gravity on time. The force of gravity, purely mathematically, can be called long-range, it instantaneously connects the interacting bodies and its calculation does not require any assumptions about the medium that transmits the interaction.
Having extended the law of gravitation to the entire Universe, Newton also considered its possible structure. He came to the conclusion that the universe is infinite. Only in this case, it can contain many space objects - centers of gravity. Within the framework of the Newtonian model of the Universe, the idea of infinite space, in which there are cosmic objects, interconnected by the force of gravity, has been established. The discovery of the basic laws of electro- and magnetostatics that followed in the second half of the 18th century, similar in mathematical form to the law of universal gravitation, further confirmed in the minds of scientists the idea of long-range forces that depend only on distance, but not on time.
The turn towards the ideas of short-range action is associated with the ideas of Faraday and Maskwell, who developed the concept of the electromagnetic field as an independent physical reality. The starting point for this was the recognition of short-range interaction and the finite rate of transmission of any interactions.
The conclusion that the wave electromagnetic field breaks away from the discharge and can independently exist and propagate in space seemed absurd. Maxwell himself stubbornly sought to derive his equations from the mechanical properties of the ether. But when Hertz experimentally discovered the existence of electromagnetic waves, this was taken as decisive proof of the validity of Maxwell's theory. The place of instantaneous long-range action was taken by short-range action transmitted at a finite speed.
2.7. Interaction, close interaction, long-range interaction
2.7.1. Short-range and long-range concepts
long range
. After the discovery of the law of universal gravitation by I. Newton, and then Coulomb's law, which describes the interaction of electric charged bodies, arose why physical bodies with mass act on each other at large distances through empty space and why charged bodies interact with each other even through an electrically neutral Wednesday?
Prior to the introduction of the concept of "field", there was no satisfactory answer to this question. For a long time it was believed that the interaction between bodies can be directly carried out through empty space, which does not take part in the transfer of interactions, and the transfer of interaction from body to body is transmitted instantly, i.e. with infinite speed. Such an assumption is the essence of the concept of long-range action, which was substantiated by R. Descartes. Most scientists adhered to this concept until the end of the 19th century.
The principle of long-range action has been established in physics also because the gravitational interaction of macroscopic bodies, in accordance with I. Newton's law of universal gravitation, is hardly noticeable - the attraction is too weak to be felt. Therefore, it was difficult to confirm or disprove experimentally. Only known experiences G. Cavendish were the first laboratory observations of gravitational attraction.
close interaction
. On the contrary, the laws of interaction of electrically charged bodies allowed for the possibility of their relatively simple verification. It was soon established that the interaction of electric charges does not occur instantly. Each electrically charged particle creates an electric field that acts on other particles not at the same moment, but after some time.
In other words, the interaction is transmitted through an intermediary - the electromagnetic field, and the propagation speed of the electromagnetic field is equal to the speed of light. This is the essence proximity concepts.
2.7.2. Fundamental types of interactions
According to the concept of short-range action, all interactions between whirligigs (in addition to direct contact between them) are carried out with the help of certain fields (for example, interaction in the theory of gravity - with the help of a gravitational field, electromagnetic interactions - with the help of electromagnetic fields). Up to the twentieth century. only two types of interactions were known: gravitational and electromagnetic.
At present, in addition to gravitational and electromagnetic interactions, two more are known - the so-called weak and strong interactions. These types of interactions in modern physics are fundamental.
Weak interaction is responsible for the intranuclear interaction, leading, for example, to the decay of a neutron with the emission of electrons (β radiation), strong interaction - for intranucleon interactions, it keeps quarks inside nucleons.
Spatially four interactions are different. Thus, gravitational and electromagnetic interactions are described by the laws of "inverse square distances" and manifest themselves formally in all space ad infinitum. Strong interactions manifest themselves only within the size of the nucleus ~10–13 cm, and weak interactions - at distances several orders of times smaller than the size of the nuclei.
The relative strength of interactions is different. If the strong interaction is conditionally taken as unity, then the electromagnetic interaction will be 10 2 times less, the weak one - 10 10 , and the gravitational one - 10 38 times less than the strong interaction.
And although the strength of interactions is significantly different, none of them can be neglected. Each interaction can have a decisive influence on the processes in a particular case. Even such an interaction as gravitational, despite its apparent smallness (10 38 times less than the strong interaction) plays, for example, a dominant role in the processes of the cosmic order, where there are objects with a huge mass and large spatial scales of phenomena.
In the second half of the XX century. intensive work was carried out on the possible unification of the electromagnetic, weak and strong interactions.
For now S. Weinberg, S. Glashow and A. Salamu managed to create a unified theory electroweak interaction. In accordance with this theory, particles are responsible for electroweak interactions - quanta of the electroweak field - bosons W~ and Z0. Soon such particles were discovered experimentally. C. Rubbia and S. van der Meer.
As noted above, the strong fundamental force is responsible for the bonding of particles in the nucleus, and is therefore often referred to as nuclear. Initially, this interaction was studied in the framework of quantum mesodynamics. Japanese scientist X Yukawa put forward the idea that the interaction between nucleons (protons and neutrons) in atomic nuclei is due to special particles - nuclear field quanta, called mesons. Subsequently, such particles were discovered and received the name π
- mesons.
The next stage in the development of the theory of strong interactions was the creation quantum chromodynamics. The need to create a new theory is explained by the following: later it was found that individual units of the nucleus - neutrons and protons - themselves consist of smaller units - quarks, so the research moved to the field of studying interactions between quarks in nucleons. According to modern concepts, in accordance with quantum chromodynamics, a strong interaction is associated with the existence of quanta of the intranucleon field by gluons. Thus, the theory of strong interactions - quantum chromodynamics - describes the interaction of quarks and gluons.
The theory of electroweak and strong interactions is called Standard model of the macrocosm.
After the unified theory of electroweak interactions was created, a real prospect of constructing a nuclear theory of all three forms of interactions of elementary particles appeared (the program of the "Great Unification").
And very recently, new ideas have appeared that open, perhaps, distant, but still real prospects for the unification of all known four interactions, including gravitational. The solution of this problem would mark a grandiose scientific revolution, which is difficult to measure by the scale of all previous scientific revolutions.
In other words, today we have a very productive research program that gives the direction of its development, which leads in an oriented way to the unity of all fundamental theories.
If such a program is implemented, it will mean that nature, ultimately, is subject to the action of a certain superpower that manifests itself in some particular interactions. This superpower is powerful enough to create our Universe, endow it with energy in the appropriate forms and matter with a certain structure.
But superpower is more than just strength. In it, matter, space-time and interaction are merged into an inseparable harmonic whole, generating such a unity of the Universe, which no one had imagined before. Modern science is in search of such unity.
The concept of physical vacuum is closely related to the concepts of interaction in physics. According to modern concepts, vacuum is not “absolute emptiness”, but a real physical system, for example, an electromagnetic field in one of its states. Moreover, according to quantum field theory, all other field states can be obtained from the vacuum state. Vacuum can be defined as a field with a minimum energy. The most complex physical transformations are constantly taking place in a vacuum, for example, a special kind of vacuum oscillations of an electromagnetic field, which do not escape from it and do not propagate, but are clearly manifested in a physical experiment.
Close action is a representation according to which the interaction between bodies distant from each other is carried out with the help of an intermediate medium (field) and is carried out at a finite speed. At the beginning of the 18th century, simultaneously with the theory of short-range action, the opposite theory of long-range action was born, according to which bodies act on each other without intermediaries, through a void, at any distance, and such interaction is carried out at an infinitely high speed (but obeys certain laws). An example of long-range action can be considered the force of universal gravitation in the classical theory of gravity by I. Newton.
M. V. Lomonosov is considered one of the founders of the theory of short-range action. Lomonosov was an opponent of the long-range theory, believing that a body cannot act on other bodies instantly. He believed that the electrical interaction is transmitted from body to body through a special medium "ether" that fills all empty space, in particular, the space between the particles that make up "weighty matter", i.e. substance. Electrical phenomena, according to Lomonosov, should be considered as certain microscopic movements occurring in the ether. The same applies to magnetic phenomena.
However, the theoretical ideas of Lomonosov and L. Euler could not be developed at that time. After the discovery of Coulomb's law, which in its form was the same as the law of universal gravitation, the theory of long-range action completely supplants the theory of short-range action. And only at the beginning of the 19th century did M. Faraday revive the theory of short-range action. According to Faraday, electric charges do not act directly on each other. Each of them creates electric and magnetic (if it moves) fields in the surrounding space. The fields of one charge act on another and vice versa. The general recognition of the theory of short-range action begins in the second half of the 19th century, after the experimental proof of the theory of J. Maxwell, who managed to give Faraday's ideas an exact quantitative form, so necessary in physics - a system of equations of the electromagnetic field.
An important difference between the theory of short-range interaction and the theory of long-range interaction is the presence of a maximum propagation velocity of interactions (fields, particles) - the speed of light. In modern physics, there is a clear division of matter into particles-participants (or sources) of interactions (called matter) and particles-carriers of interactions (called field). Of the four types of fundamental interactions, three have received reliable experimental verification of the existence of carrier particles: strong, weak, and electromagnetic interactions. Currently, attempts are being made to detect carriers of gravitational interaction - the so-called
long range . After the discovery of the law of universal gravitation by I. Newton, and then Coulomb's law, which describes the interaction of electric charged bodies, the question arose why physical bodies with mass act on each other at large distances through empty space and why charged bodies interact with each other even through electrically charged bodies. neutral environment?
Prior to the introduction of the concept of "field", there was no satisfactory answer to this question. For a long time it was believed that the interaction between bodies can be directly carried out through empty space, which does not take part in the transfer of interactions, and the transfer of interaction from body to body is transmitted instantly, i.e. with infinite speed. Such an assumption is the essence of the concept of long-range action, which was substantiated by R. Descartes. Most scientists adhered to this concept until the end of the 19th century.
The principle of long-range action has been established in physics also because the gravitational interaction of macroscopic bodies, in accordance with I. Newton's law of universal gravitation, is hardly noticeable - the attraction is too weak to be felt. Therefore, it was difficult to confirm or disprove experimentally. Only known experiences G. Cavendish were the first laboratory observations of gravitational attraction.
close interaction . On the contrary, the laws of interaction of electrically charged bodies allowed for the possibility of their relatively simple verification. It was soon established that the interaction of electric charges does not occur instantly. Each electrically charged particle creates an electric field that acts on other particles not at the same moment, but after some time.
In other words, the interaction is transmitted through an intermediary - the electromagnetic field, and the propagation speed of the electromagnetic field is equal to the speed of light. This is the essence proximity concepts.
Close range and long range- these are mutually opposite views for explaining the interaction of material structures. By concept close action any interaction on material objects can be transmitted only between neighboring points in space in a finite period of time. long range allows action at a distance instantly with infinite speed, i.e., in fact, outside of time and space. After Newton, this concept was widely used in physics, although he himself understood that the long-range forces introduced by him (for example, gravitational forces) are only a formal approximate device that makes it possible to give a description of observed phenomena that is correct to some extent. The final approval of the principle of short-range action came with the development of the concept of the physical field as a material medium. The field equations describe the state of the system at a given point at a given time as dependent on the state at the nearest previous moment at the nearest neighboring point. If an electromagnetic field can exist independently of a material carrier, then the electrical interaction cannot be explained by an instantaneous action at a distance. Therefore, Newton's long-range action gave way to short-range action, fields propagating in space at a finite speed. Thus, according to modern science, interactions between structures are transmitted through the corresponding field at a finite speed equal to the speed of light in vacuum.
The whole set of elementary particles with their interactions manifests itself macroscopically in the form of matter and
fields. The field, unlike matter, has special properties. The physical reality of the electromagnetic field is visible at least from the fact that radio waves exist. The source of the electromagnetic field are moving charged particles. The interaction of charges occurs according to the scheme: particle - field - particle. The field is the carrier of interaction. Under certain conditions, the field can "break away" from its sources and freely propagate in space. Such a field has a wave character.
How do you get information about the state of matter in stars? The atomic processes that take place in the outer shells of stars are accompanied by the emission of electromagnetic waves. One of these processes is the excitation of atoms, leading to the emission of a number of characteristic "portions" of electromagnetic field energy (spectrum). Each chemical element has its own unique radiation spectrum. By analyzing, for example, sunlight (light is electromagnetic radiation) using optical instruments, it is possible to determine the chemical composition and percentage of elements in the outer shells of the Sun.
In the modern natural-science picture of the world, both the substance and the field consist of elementary particles, and the particles interact with each other, mutually transform. At the level of elementary particles there is an interconversion of the field and matter. So, photons can turn into electron-positron pairs, and these pairs are annihilated (annihilated) in the process of interaction with the formation of photons. Moreover, the vacuum also consists of particles (virtual particles) that interact both with each other and with ordinary particles. Thus, the borders between matter and field and even between vacuum, on the one hand, and matter and field, on the other, actually disappear. At a fundamental level, all the facets in nature really turn out to be conditional. In the modern natural-scientific picture of the world, matter and field interconvert. Therefore, at present
time, persistent attempts are being made to create a unified theory of all types of interactions.
In the presence of several fields, to determine the resulting interaction, apply superposition principle. The principle of superposition in natural science makes it possible to obtain the resulting effect from the superimposition (superposition) of several independent interactions as the sum of the effects caused by each interaction separately. It is valid for systems described by linear equations. The principle of superposition is widely used in mechanics, the theory of oscillations and the wave theory of physical fields. In quantum mechanics, the principle of superposition refers to wave functions. According to this, if a physical system can be in states described by two or more functions, then the system can also be in a state described by any linear combination of these functions.
17. The concept of interaction. The concept of long range and short range.
Under interaction in a narrower sense, they understand such processes in the course of which between interacting structures and systems there is an exchange of quanta of certain fields, energy, and sometimes information.
At present, it is generally accepted that any interactions of any objects can be reduced to a limited class of four main types of fundamental interactions: strong, electromagnetic, weak and gravitational. The intensity of interaction is usually characterized by the so-called interaction constant, which is a dimensionless parameter that determines the probability of processes due to this type of interaction. The ratio of the values of the constants gives the relative intensity of the corresponding interactions.
Concepts of long range and short range.
Close range and long range- these are mutually opposite views for explaining the interaction of material structures. By concept short range any interaction on material objects can be transmitted only between neighboring points in space in a finite period of time. long range allows action at a distance instantly with infinite speed, i.e., in fact, outside of time and space. After Newton, this concept was widely used in physics, although he himself understood that the long-range forces introduced by him (for example, gravitational forces) are only a formal approximate device that makes it possible to give a description of observed phenomena that is correct to some extent. The final approval of the principle of short-range action came with the development of the concept of the physical field as a material medium. The field equations describe the state of the system at a given point at a given time as dependent on the state at the nearest previous moment at the nearest neighboring point. If an electromagnetic field can exist independently of a material carrier, then the electrical interaction cannot be explained by an instantaneous action at a distance. Therefore, Newton's long-range action gave way to short-range action, fields propagating in space at a finite speed. Thus, according to modern science, interactions between structures are transmitted through the corresponding field at a finite speed equal to the speed of light in vacuum.
18. Characteristics of the main types of interaction (gravitational, electromagnetic, strong and weak).
1. Gravitational interaction is universal, but it is not taken into account in the microcosm, since it is the weakest of all interactions and manifests itself only in the presence of sufficiently large masses. Its range is not limited, time is also not limited. The exchange nature of the gravitational interaction is still in question, since the hypothetical fundamental particle - the graviton - has not yet been discovered.
(I. Newton) - the weakest interaction.
2. Electromagnetic interaction: constant of the order of 10 -2 , interaction radius is not limited, interaction time t ~ 10 -20 s. It is realized between all charged particles. The carrier particle is a photon (γ-quantum).
(Pendant).
3. Weak interaction is associated with all types of β-decay; it is responsible for many decays of elementary particles and the interaction of neutrinos with matter. The interaction constant is about 10 -13 , t ~ 10 -10 s. This interaction, like the strong one, is short-range: the interaction radius is r~10 -18 m. Carrier particles are an intermediate vector boson: W + , W - , Z 0 .(Fermi).
4. Strong interaction ensures the bonding of nucleons in the nucleus. The interaction constant is taken equal to 1, the radius of action is about 10 -15 m, the flow time is t ~ 10 -23 s. Strong interaction is carried out between quarks - particles that make up protons and neutrons - with the help of the so-called. gluons. (Yukawa).
