The concepts "Universe" and "Metagalaxy" are very close concepts: they characterize the same object, but in different aspects. The concept "Universe" refers to the entire existing material world; the concept of "Metagalaxy" is the same world, but from the point of view of its structure - as an ordered system of galaxies.

In classical science, there was the so-called theory of the stationary state of the Universe, according to which the Universe has always been almost the same as it is now. Astronomy was static: the motions of planets and comets were studied, stars were described, their classifications were created, which was, of course, very important. But the question of the evolution of the Universe was not raised.

In this test work the main cosmological models The universe.

1.1 Modern cosmological models of the Universe: A. Einstein's model, A.A. Friedman

Modern cosmological models of the Universe are based on A. Einstein's general theory of relativity, according to which the metric of space and time is determined by the distribution of gravitational masses in the Universe. Its properties as a whole are determined by the average density of matter and other specific physical factors.

Einstein's equation of gravitation has not one, but many solutions, which explains the presence of many cosmological models of the Universe. The first model was developed by A. Einstein himself in 1917. He rejected the postulates of Newtonian cosmology about the absoluteness and infinity of space and time. In accordance with A. Einstein's cosmological model of the Universe, the world space is homogeneous and isotropic, matter is, on average, evenly distributed in it, the gravitational attraction of masses is compensated by the universal cosmological repulsion.

The time of existence of the Universe is infinite, that is, it has neither beginning nor end, and space is infinite, but of course.

The universe in A. Einstein's cosmological model is stationary, infinite in time and boundless in space.

In 1922 the Russian mathematician and geophysicist A. A Fridman rejected the postulate of classical cosmology about the stationarity of the Universe and obtained a solution to the Einstein equation describing the Universe with "expanding" space.

The ratio of the average density of the universe to critical is denoted

There are three cosmological models, depending on, after their creator named Friedman. These models do not take into account the vacuum energy (cosmological constant).

I Friedman model,. The expansion of the universe will be eternal, and the speeds of galaxies will never tend to zero. The space in such a model is infinite, has negative curvature, and is described by Lobachevsky's geometry. Through each point of such a space, you can draw an infinite set of straight lines parallel to a given one, the sum of the angles of the triangle is less than 180 °, the ratio of the circumference to the radius is greater than 2π.

II Friedman model,. The expansion of the universe will be eternal, but in infinity its speed will tend to zero. The space in such a model is infinite, flat, described by the geometry of Euclid.

III Friedman model,. The expansion of the universe will be replaced by contraction, collapse and will end with the universe shrinking into a singular point (Big Crunch). The space in such a model is finite, has a positive curvature, is a three-dimensional hypersphere in shape, and is described by the spherical geometry of Riemann. In such a space there are no parallel straight lines, the sum of the angles of the triangle is more than 180 °, the ratio of the circumference to the radius is less than 2π. The total total mass of such a universe is zero.

According to modern data .

1.2 Alternative cosmological models of the Universe

except standard model The Big Bang, in principle, there are alternative cosmological models:

1. The model, symmetric with respect to matter and antimatter, assumes the equal presence of these two types of matter in the Universe. Although it is obvious that our Galaxy contains practically no antimatter, neighboring stellar systems could well consist entirely of it; in this case, their radiation would be exactly the same as that of normal galaxies. However, in earlier epochs of expansion, when matter and antimatter were in closer contact, their annihilation should have produced powerful gamma rays. Observations do not detect it, which makes a symmetric model unlikely.

2. The Cold Big Bang model assumes that the expansion began at absolute zero. True, in this case, nuclear fusion must also occur and heat the substance, but the microwave background radiation can no longer be directly associated with the Big Bang, but must be explained in some other way. This theory is attractive because the matter in it is subject to fragmentation, which is necessary to explain the large-scale inhomogeneity of the Universe.

3. The stationary cosmological model assumes the continuous creation of matter. The basic premise of this theory, known as the Ideal Cosmological Principle, states that the universe has always been and will remain as it is today. Observations refute this.

4. Modified versions of Einstein's theory of gravity are considered. For example, the theory of K. Bruns and R. Dicke from Princeton generally agrees with observations within Solar system... The Brans - Dicke model, as well as the more radical Hoyle model, in which some fundamental constants change over time, have almost the same cosmological parameters in our era as the Big Bang model.

5. In 1927 the Belgian abbot and scientist J. Lemaitre linked the "expansion" of space with the data of astronomical observations. Lemaitre introduced the concept of the beginning of the Universe as a singularity (i.e., a superdense state) and the birth of the Universe as a Big Bang. On the basis of the modified Einstein theory, J. Lemaitre in 1925 built a cosmological model that combines Big Bang with a prolonged quiescent phase during which galaxies could form. Einstein became interested in this opportunity to substantiate his favorite cosmological model of a static universe, but when the expansion of the universe was discovered, he publicly abandoned it.

ΛCDM (read "Lambda-CDiM") - short for Lambda-Cold Dark Matter, the modern standard cosmological model in which the spatially flat Universe is filled, in addition to ordinary baryonic matter, with dark energy (described by the cosmological constant Λ in Einstein's equations) and cold dark matter (English Cold Dark Matter). According to this model, the age of the universe is billions of years.

Since the average density of matter in the Universe is unknown, today we do not know in which of these spaces of the Universe we live.

In 1929, the American astronomer E.P. Hubble discovered the existence of a strange relationship between the distance and the speed of galaxies: all galaxies move away from us, and with a speed that increases in proportion to the distance - the system of galaxies expands.

The expansion of the universe is considered a scientifically established fact. According to theoretical calculations by J. Lemaitre, the radius of the Universe in its original state was 10-12 cm, which is close in size to the radius of an electron, and its density was 1096 g / cm3. In a singular state, the Universe was a micro-object of negligible size. From the original singular state, the universe went on to expand as a result of the Big Bang.

Retrospective calculations determine the age of the Universe at 13-20 billion years. GA Gamov suggested that the temperature of matter was high and fell with the expansion of the Universe. His calculations showed that the Universe in its evolution goes through certain stages, during which the formation of chemical elements and structures occurs. In modern cosmology, for clarity, the initial stage of the evolution of the Universe is divided into "eras"

When assessing the immensity of the scale of the Universe, the classical philosophical question always arises: is the Universe finite or infinite? The concept of infinity is mainly used by mathematicians and philosophers. Experimental physicists who are proficient in experimental methods and measurement techniques always obtain the final values ​​of the measured quantities. The enormous importance of science and especially modern physics lies in the fact that by now many quantitative characteristics of objects not only of the macro- and microcosm, but also of the megaworld have already been obtained.

The spatial scales of our Universe and the dimensions of the main material formations, including micro-objects, can be represented from the following table, where the dimensions are given in meters (for simplicity, only orders of numbers are given, that is, approximate numbers within one order of magnitude):

Cosmological horizon radius

or the Universe we see 10 26

The diameter of our Galaxy is 10 21

Distance from Earth to Sun 10 11

Diameter of the Sun 10 9

Person size 10 0

Visible light wavelength 10 -6 - 10 -8

Virus size 10 -6 -10 -8

Hydrogen atom diameter 10 -10

Atomic nucleus diameter 10 -15

Minimum distance,

available today to our measurements 10 -18

From these data, it can be seen that the ratio of the largest to the smallest size available to today's experiment is 44 orders of magnitude. With the development of science, this attitude has constantly increased and will continue to grow as new knowledge about the world around us is accumulated. After all, “our world is only a school where we learn to learn,” said the French humanist philosopher Michel Montaigne (1533-1592).

Structurality is inherent in the universe at various levels, from conventionally elementary particles to giant superclusters of galaxies. The modern structure of the Universe is the result of cosmic evolution, during which galaxies were formed from protogalaxies, stars from protostars, and planets from a protoplanetary cloud.

1.3 Hot Explosion Model

According to the Friedmann-Lemaitre cosmological model, the Universe arose at the time of the Big Bang - about 20 billion years ago, and its expansion continues to this day, gradually slowing down. In the first instant of the explosion, the matter of the Universe had infinite density and temperature; this state is called a singularity. According to general relativity, gravity is not a real force, but a curvature of space-time: the greater the density of matter, the stronger the curvature. At the moment of the initial singularity, the curvature was also infinite. You can express the infinite curvature of space-time in other words, saying that at the initial moment, matter and space exploded simultaneously everywhere in the Universe. As the volume of space of the expanding Universe increases, the density of matter in it decreases.

S. Hawking and R. Penrose proved that in the past there was certainly a singular state, if the general theory of relativity is applicable to describe physical processes in the very early Universe. To avoid a catastrophic singularity in the past, it is necessary to significantly change physics, for example, by assuming the possibility of spontaneous continuous creation of matter, as in the theory of a stationary universe. But astronomical observations do not provide any basis for this. The earlier events we consider, the smaller their spatial scale was; as one approaches the beginning of the expansion, the observer's horizon contracts (Fig. 1).

Rice. 1. Illustration of Big Bang Models

In the very first moments, the scale is so small that we no longer have the right to apply general relativity: quantum mechanics is required to describe phenomena on such a small scale. But the quantum theory of gravity does not yet exist, so no one knows how events developed until 10-43 s, called Planck time (in honor of the father of quantum theory). At that moment, the density of matter reached an incredible value of 1090 kg / cm 3, which cannot be compared not only with the density of the bodies around us (less than 10 g / cm 3), but even with the density of the atomic nucleus (about 1012 kg / cm 3) - the highest density available in the laboratory. Therefore, for modern physics, the beginning of the expansion of the Universe is the Planck time.

There are three major types of Big Bang models: the standard open model, the standard closed model, and the Lemaitre model. Time is plotted horizontally, while the vertical is the distance between any two galaxies that are sufficiently distant from each other (to exclude their interaction). The circle marks our era. If the Universe were always expanding at the current rate, expressed by the Hubble constant H, then this would begin about 20 billion years ago and proceed as shown by the diagonal dotted line. If the expansion slows down, as in an open model of a spatially unlimited world or in a closed model of a limited world, then the age of the Universe is less than 1 / H. The closed model has the smallest age, the expansion of which quickly slows down and gives way to compression. Lemaitre's model describes a Universe that is significantly older than 1 / H, since there is a long period in its history when there was almost no expansion. The Lemaitre model and the open model describe a universe that will always expand.

It was under such conditions of inconceivably high temperature and density that the birth of the Universe took place. Moreover, this could be a birth in the literal sense: some cosmologists (say, Ya.B. Zeldovich in the USSR and L. Parker in the USA) believed that particles and gamma photons were born in that era by the gravitational field. From the point of view of physics, this process could take place if the singularity was anisotropic, i.e. the gravitational field was inhomogeneous. In this case, tidal gravitational forces could "pull" real particles out of the vacuum, thus creating the substance of the Universe. Studying the processes that took place immediately after the Big Bang, we understand that our physical theories are still very imperfect. The thermal evolution of the early Universe depends on the production of massive elementary particles - hadrons, about which nuclear physics still knows little. Many of these particles are unstable and short-lived.

The Swiss physicist R. Hagedorn believes that there may be a great many hadrons of increasing masses, which could be formed in abundance at a temperature of the order of 10 12 K, when the gigantic radiation density led to the production of hadron pairs consisting of a particle and an antiparticle. This process would have to limit the rise in temperature in the past. According to another point of view, the number of types of massive elementary particles is limited, so the temperature and density during the hadron era had to reach infinite values. In principle, this could be verified: if the constituent hadrons - quarks - were stable particles, then a certain number of quarks and antiquarks should have survived from that hot era. But the search for quarks was in vain; they are most likely unstable.

After the first millisecond of the expansion of the Universe, the strong (nuclear) interaction ceased to play a decisive role in it: the temperature dropped so much that atomic nuclei ceased to be destroyed. Further physical processes were determined by the weak interaction responsible for the production of light particles - leptons (i.e. electrons, positrons, mesons and neutrinos) under the action of heat radiation... When, in the course of expansion, the radiation temperature dropped to about 10 10 K, lepton pairs ceased to be produced, almost all positrons and electrons annihilated; there were only neutrinos and antineutrinos, photons and a few protons and neutrons preserved from the previous epoch. Thus ended the lepton era. The next phase of expansion - the photon era - is characterized by the absolute predominance of thermal radiation. For every proton or electron that remains, there are a billion photons. At first, these were gamma quanta, but as the Universe expanded, they lost energy and became X-ray, ultraviolet, optical, infrared and, finally, now they have become radio quanta, which we take as blackbody background (relic) radio emission.

1.4 Unsolved problems of Big Bang cosmology

There are 4 problems that are now facing the cosmological model of the Big Bang.

1. The singularity problem: many question the applicability of general relativity, which gives a singularity in the past. Alternative cosmological theories free of singularity are proposed.

2. Closely related to the singularity is the problem of the isotropy of the Universe. It seems strange that the expansion, which began with a singular state, turned out to be so isotropic. It is not excluded, however, that the initially anisotropic expansion gradually became isotropic under the action of dissipative forces.

3. Homogeneous on the largest scales, on smaller scales, the Universe is very heterogeneous (galaxies, clusters of galaxies). It is difficult to understand how gravity alone could have produced such a structure. Therefore, cosmologists are studying the possibilities of inhomogeneous models of the Big Bang.

4. Finally, one may ask, what is the future of the universe? To answer, you need to know the average density of matter in the Universe. If it exceeds a certain critical value, then the geometry of space-time is closed, and in the future the Universe will certainly shrink. The closed Universe has no boundaries, but its volume is finite. If the density is below critical, then the Universe is open and will expand forever. The open universe is infinite and has only one singularity at the beginning. So far, the observations are in better agreement with the open universe model. The origin of the large-scale structure. Cosmologists have two opposite points of view on this problem. The most radical is that in the beginning there was chaos. The expansion of the early Universe was extremely anisotropic and inhomogeneous, but then dissipative processes smoothed out the anisotropy and brought the expansion closer to the Friedmann-Lemaitre model. The fate of the inhomogeneities is very curious: if their amplitude was large, then inevitably they should have collapsed into black holes with a mass determined by the current horizon. Their formation could begin right from the Planck time, so that the Universe could have many small black holes with masses up to 10-5 g. However, S. Hawking showed that "mini-holes" should, by emitting, lose their mass, and before epoch, only black holes with masses of more than 10 16 g could survive, which corresponds to the mass of a small mountain.

Primary chaos could contain disturbances of any scale and amplitude; the largest of them in the form of sound waves could have survived from the era of the early Universe to the era of radiation, when matter was still hot enough to emit, absorb and scatter radiation. But with the end of this era, the cooled plasma recombined and stopped interacting with radiation. The pressure and speed of sound in the gas dropped, causing the sound waves to turn into shock waves, compressing the gas and causing it to collapse into galaxies and clusters. Depending on the type of initial waves, the calculations predict a very different picture, which does not always correspond to the observed one. To choose between possible options cosmological models, one philosophical idea is important, known as the anthropic principle: from the very beginning, the universe should have had such properties that allowed galaxies, stars, planets and intelligent life to form in it. Otherwise, there would be no one to deal with cosmology. An alternative point of view is that nothing more can be learned about the original structure of the universe than what observations give. According to this conservative approach, the young universe cannot be considered chaotic, since it is now very isotropic and homogeneous. The deviations from uniformity that we observe in the form of galaxies could have grown under the influence of gravity from small initial density irregularities. However, studies of the large-scale distribution of galaxies (mainly by J. Peebles at Princeton) do not seem to support this idea. Another interesting possibility is that clusters of black holes born in the hadronic era could have been the initial fluctuations for the formation of galaxies. Is the Universe open or closed? The nearest galaxies are moving away from us at a speed, proportional to distance; but the more distant ones do not obey this dependence: their movement indicates that the expansion of the Universe is slowing down with time. In a closed model of the Universe under the action of gravity, expansion at a certain moment stops and is replaced by contraction (Fig. 2), but observations show that the deceleration of galaxies is still not so fast that a complete stop ever occurs.

The horizontal lines mark the characteristic moments of evolution, and the triangles cut off by them show the region of the Universe accessible to the observer at that moment. The more time has passed from the beginning of the expansion, the larger the area becomes available for observation. Currently, light comes to us from stars, quasars and galaxy clusters billions of light-years away, but in early eras, an observer could see a much smaller region of the universe. In different epochs, different forms of matter dominated: although the matter of atomic nuclei (nucleons) dominates, before that, when the Universe was hot, radiation (photons) dominated, and even earlier - light elementary particles (leptons) and heavy (hadrons).

Figure 2 - The standard big bang model: time is plotted vertically and distances are plotted horizontally.

For the Universe to be closed, the average density of matter in it must exceed a certain critical value. The density estimates for visible and invisible matter are very close to this value. The distribution of galaxies in space is very heterogeneous. Our Local Group of galaxies, which includes the Milky Way, the Andromeda Nebula and several smaller galaxies, lies on the periphery of a vast galaxy system known as the Virgo Supercluster, whose center coincides with the Virgo cluster of galaxies. If the average density of the world is high and the Universe is closed, then a strong deviation from isotropic expansion should be observed, caused by the attraction of our and neighboring galaxies to the center of the Supercluster. In an open universe, this deviation is insignificant. The observations are rather consistent with the open model. Of great interest to cosmologists is the content in cosmic matter of the heavy isotope of hydrogen - deuterium, which was formed during nuclear reactions in the first moments after the Big Bang. The deuterium content turned out to be extremely sensitive to the density of matter in that era, and therefore in ours. However, the "deuterium test" is not easy to carry out, because it is necessary to investigate the primary matter, which has not been in the interiors of stars since the moment of cosmological synthesis, where deuterium easily burns up. The study of extremely distant galaxies has shown that the deuterium content corresponds to the low density of matter and, therefore, to the open model of the Universe.

Conclusion

Cosmological models lead to the conclusion that the fate of the expanding Universe depends only on the average density of the substance filling it and on the value of the Hubble constant. If the average density is equal to or below some critical density, the expansion of the universe will continue forever. If the density turns out to be higher than the critical one, then sooner or later the expansion will stop and be replaced by compression.

In this case, the Universe will shrink to the size that it supposedly had when it originated, giving way to a phenomenon called the Great Compression.

Let's list the basic models of the Universe: De Sitter's model: the model of the expanding Universe, proposed in 1917, in which there is no matter or radiation. This unrealistic hypothesis was nevertheless historically significant, since it was the first to put forward the idea of ​​an expanding rather than a static universe; Lemaitre Model: A model of the universe that begins with a Big Bang followed by a static phase followed by infinite expansion. The model is named for J. Lemaitre (1894-1966),

A model of an expanding universe without general relativity, proposed in 1948 by Edward Milne. It is an expanding, isotropic and homogeneous universe. containing no substance. It has negative curvature and is not closed.

Friedman's Model: A model of the universe that can collapse inward. In 1922, the Soviet mathematician A.A. Friedman (Alexander Friedmann, 1888-1925), analyzing the equations of the general theory of relativity

Friedmann's universe can be closed if the density of matter in it is large enough to stop expansion. This fact led to the search for the so-called missing mass. Subsequently, Friedman's conclusions were confirmed in astronomical observations, which discovered in the spectra of galaxies the so-called redshift of spectral lines, which corresponds to the mutual distance of these stellar systems.

Einstein-de Sitter model: The simplest of modern cosmological models, in which the Universe has zero pressure, zero curvature (i.e. flat geometry) and infinite extent, and its expansion is not limited in space and time. Proposed in 1932, this model is a special case (at zero curvature) of the more general Friedman universe.

2. What is the essence of self-organization processes in animate and inanimate nature?

All objects of animate and inanimate nature can be represented in the form of certain systems with specific features and properties that characterize their level of organization. Taking into account the level of organization, the hierarchy of the organization structures of material objects of animate and inanimate nature can be considered. Such a hierarchy of structures begins with elementary particles, which represent the initial level of organization of matter, and ends with living organizations and communities - the highest levels of organization.

Currently, in the field of fundamental theoretical physics, concepts are being developed, according to which the objectively existing world is not limited to the material world perceived by our senses or physical devices. The authors of these concepts came to the following conclusion: along with the material world, there is a reality of a higher order, which has a fundamentally different nature in comparison with reality material world.

The study of matter and its structural levels is a necessary condition for the formation of a worldview, regardless of whether it ultimately turns out to be materialistic or idealistic.

It is quite obvious that the role of defining the concept of matter, understanding the latter as inexhaustible for constructing scientific picture of the world, solving the problem of reality and cognizability of objects and phenomena of micro, macro and mega worlds.

By the organization of the system we mean the change in the structure of the system, which ensures consistent behavior, or the functioning of the system, which is determined by external conditions.

If the change in organization is understood as a change in the method of connection (or connection) of subsystems that form a system, then the phenomenon of self-organization can be defined as such an inevitable change in the system and its functions, which occurs outside of any additional influences, due to the interaction of the system with the conditions of existence and approaches some relatively stable state.

By self-organization we mean a change in structure that ensures consistency of behavior due to the presence of internal connections and connections with external environment.

Self-organization is a natural-scientific expression of the process of self-motion of matter. The ability to self-organize is possessed by systems of animate and inanimate nature, as well as artificial systems. The specific configuration of the structure exists only under strictly defined conditions and at a certain moment of the "movement" of a complex system. The dynamics of systems development leads to a consistent change in their structures.

The natural change in the structure of the system in accordance with the historical changes in the relationship with the external environment is called evolution.
Changing the structure of a complex system in the process of its interaction with environment- this is a manifestation of the property of openness as an increase in the possibilities for coming out to the new. On the other hand, a change in the structure of a complex system provides an expansion of living conditions associated with a more complex organization and an increase in vital activity, i.e. the acquisition of devices of a more general meaning, allowing to establish connections with new aspects of the external environment.

Self-organization is characterized by the emergence of internally coordinated functioning due to internal connections and connections with the external environment. Moreover, the concepts of function and structure of the system are closely interrelated; the system is organized, i.e. changes the structure for the sake of performing the function.

Structurality and systemic organization of matter are among its most important attributes, express the orderliness of the existence of matter and those specific forms in which it manifests itself.

The structure of matter is usually understood as its structure in the macrocosm, i.e. existence in the form of molecules, atoms, elementary particles, etc. This is due to the fact that a person is a macroscopic being and macroscopic scales are familiar to him, therefore the concept of structure is usually associated with various micro-objects.

But if we consider matter as a whole, then the concept of the structure of matter will also cover macroscopic bodies, all cosmic systems of the megaworld, and in any arbitrarily large space-time scales. From this point of view, the concept of "structure" is manifested in the fact that it exists in the form of an infinite variety of integral systems, closely interconnected with each other, as well as in the orderliness of the structure of each system. Such a structure is infinite in quantitative and qualitative terms.

The manifestations of the structural infinity of matter are:

- inexhaustibility of objects and processes of the microworld;

- infinity of space and time;

- infinity of changes and development of processes.

Of the whole variety of forms of objective reality, only the finite area of ​​the material world remains empirically accessible, which now extends on a scale from 10 -15 to 10 28 cm, and in time - up to 2 × 10 9 years.

Structurality and systemic organization of matter are among its most important attributes. They express the orderliness of the existence of matter and those of its specific forms in which it manifests itself.

The material world is one: we mean that all its parts - from inanimate objects to living beings, from celestial bodies to a person as a member of society - are somehow connected.

A system is something that is connected in a certain way with each other and is subject to the relevant laws.

Systems are objectively existing and theoretical, or conceptual, i.e. existing only in the mind of a person.

A system is an internal or external ordered set of interconnected and interacting elements.

The orderliness of the set implies the presence of regular relationships between the elements of the system, which manifests itself in the form of laws of structural organization. All natural systems that arise as a result of the interaction of bodies and the natural self-development of matter have internal orderliness. External is characteristic of man-made artificial systems: technical, production, conceptual, etc.

Structural levels of matter are formed from a certain set of objects of any class and are characterized by a special type of interaction between their constituent elements.

The criterion for distinguishing various structural levels is the following features:

- space-time scales;

- a set of the most important properties;

- specific laws of motion;

- the degree of relative complexity that arises in the process historical development matter in a given area of ​​the world;

- some other signs.

The currently known structural levels of matter can be distinguished on the basis of the above criteria in the following areas.

1. Microcosm. These include:

- elementary particles and atomic nuclei - an area of ​​the order of 10 - 15 cm;

- atoms and molecules 10 –8 –10 –7 cm.

The microcosm is molecules, atoms, elementary particles - the world of extremely small, not directly observable micro-objects, the spatial diversity of which is calculated from 10 -8 to 10 -16 cm, and the life time - from infinity to 10 -24 s.

2. Macrocosm: macroscopic bodies 10 -6 -10 7 cm.

Macrocosm - the world of stable forms and proportional human values, as well as crystal complexes of molecules, organisms, communities of organisms; the world of macro-objects, the dimension of which is comparable to the scale of human experience: spatial quantities are expressed in millimeters, centimeters and kilometers, and time - in seconds, minutes, hours, years.

Megaworld is a planet, stellar complexes, galaxies, metagalaxies - a world of huge cosmic scales and speeds, the distance in which is measured in light years, and the lifetime of cosmic objects - in millions and billions of years.

And although these levels have their own specific laws, micro-, macro- and megaworlds are closely interconnected.

3. Megaworld: space systems and unlimited scales up to 1028 cm.

Different levels of matter are characterized by different types connections.

On a scale of 10-13 cm - strong interactions, the integrity of the nucleus is ensured by nuclear forces.


The integrity of atoms, molecules, macro-bodies is provided by electromagnetic forces.


1. On a cosmic scale - gravitational forces.
   

   With an increase in the size of objects, the interaction energy decreases. If we take the energy of gravitational interaction as a unit, then the electromagnetic interaction in the atom will be 1039 times greater, and the interaction between nucleons - the particles that make up the nucleus - will be 1041 times larger. The smaller the size of material systems, the more firmly their elements are interconnected.
   

   The division of matter into structural levels is relative. On the available space-time scales, the structure of matter manifests itself in its systemic organization, existence in the form of a multitude of hierarchically interacting systems, ranging from elementary particles to the Metagalaxy.
   

   Speaking about structuralness - the internal dismemberment of material existence, it can be noted that no matter how wide the range of the worldview of science, it is closely related to the discovery of more and more new structural formations. For example, if earlier the view of the Universe was closed by the Galaxy, then expanded to a system of galaxies, now the Metagalaxy is studied as a special system with specific laws, internal and external interactions.
   

   In modern science, the method is widely used structural analysis, which takes into account the consistency of the objects under study. After all, structuralness is the internal dismemberment of material existence, the way of existence of matter. The structural levels of matter are formed from a certain set of objects of any kind and are characterized by a special way of interaction between their constituent elements, in relation to the three main spheres of objective reality, these levels look as follows (table).
   

   Table - Structural levels of matter
   

   Inorganic nature	Live nature	Society
   Submicroelemental	Biological macromolecular	Individual
   Microelement	Cellular	A family
   Nuclear	Microorganic	Collectives
   Atomic	Organs and tissues	Large social groups (classes, nations)
   Molecular	The whole organism	State (civil society)
   Macro level	Populations	Systems of states
   Mega-level (planets, star-planetary systems, galaxies)	Biocenosis	Humanity as a whole
   Mega-level (metagalaxy)	Biosphere	Noosphere

   Each of the spheres of objective reality includes a number of interrelated structural levels. Within these levels, coordination relations are dominant, and between levels - subordinate ones.
   

   A systematic study of material objects involves not only the establishment of methods for describing relationships, connections and the structure of a set of elements, but also the identification of those of them that are system-forming, i.e. provide separate functioning and development of the system. A systematic approach to material formations presupposes the possibility of understanding the system under consideration more high level... The system is usually characterized by a hierarchical structure, i.e. sequential inclusion of a system of a lower level into a system of a higher level.
   

   Thus, the structure of matter at the level of inanimate nature (inorganic) includes elementary particles, atoms, molecules (objects of the microworld, macro-objects and objects of the megaworld: planets, galaxies, systems of metagalaxies, etc.). The metagalaxy is often identified with the entire Universe, but the Universe is understood in the broadest sense of the word, it is identical to the entire material world and moving matter, which may include many metagalaxies and other cosmic systems.
   

   Wildlife is also structured. It highlights the biological and social levels. The biological level includes sublevels:
   

   - macromolecules ( nucleic acids, DNA, RNA, proteins);
   

   – cellular level;
   

   - microorganic ( unicellular organisms);
   

   - organs and tissues of the body as a whole;
   

   - population;
   

   - biocenotic;
   

   - biosphere.
   

   The main concepts of this level at the last three sublevels are the concepts of biotope, biocenosis, biosphere, which require explanation.
   

   A biotope is a collection (community) of individuals of the same species (for example, a pack of wolves) that can interbreed and reproduce their own kind (populations).
   

   Biocenosis is a set of populations of organisms in which the waste products of some are the conditions for the existence of other organisms inhabiting a land or water area.
   

   The biosphere is a global system of life, that part of the geographic environment (the lower part of the atmosphere, the upper part of the lithosphere and hydrosphere), which is the habitat of living organisms, providing the conditions necessary for their survival (temperature, soil, etc.), formed as a result of interaction biocenoses.
   

   The general basis of life at the biological level - organic metabolism (exchange of matter, energy and information with the environment) - manifests itself at any of the highlighted sublevels:
   

   - at the level of organisms, metabolism means assimilation and dissimilation through intracellular transformations;
   

   - at the level of ecosystems (biocenosis), it consists of a chain of transformations of a substance initially assimilated by producing organisms through the mediation of consumer organisms and destructive organisms belonging to different species;
   

   - at the level of the biosphere, there is a global circulation of matter and energy with the direct participation of cosmic-scale factors.
   

   At a certain stage in the development of the biosphere, special populations of living beings arise, which, due to their ability to work, have formed a peculiar level - the social one. In the structural aspect, social reality is divided into sublevels: individuals, families, various collectives (production), social groups, etc.
   

   The structural level of social activity is in an ambiguous linear relationship with each other (for example, the level of nations and the level of states). The intertwining of different levels within society gives rise to the idea of ​​the dominance of chance and chaos in social activity. But a careful analysis reveals the presence of fundamental structures in it - the main spheres of social life, which are material-production, social, political, spiritual spheres, which have their own laws and structures. All of them, in a certain sense, are subordinated as part of the socio-economic formation, are deeply structured and determine the genetic unity of social development as a whole.
   

   Thus, any of the three areas of material reality is formed from a number of specific structural levels, which are in strict order within a particular area of ​​reality.
   

   The transition from one area to another is associated with the complication and increase in the set of formed factors that ensure the integrity of systems. Within each of the structural levels, there are subordination relations ( molecular level includes atomic, not vice versa). The regularities of the new levels are not reducible to the regularities of the levels on the basis of which they arose, and are the leading ones for a given level of organization of matter. Structural organization, i.e. consistency, is a way of existence of matter.
   

   The hypothesis of a multivalent model of the Universe

   Foreword by the author of the site: the readers of the site "Knowledge is Power" are offered fragments from the 29th chapter of the book "Memories" by Andrei Dmitrievich Sakharov. Academician Sakharov talks about the work in the field of cosmology, which he did after he began to actively engage in human rights work - in particular, in exile in Gorky. This material is of undoubted interest on the topic "Universe" discussed in this chapter of our site. We will get acquainted with the hypothesis of a multivalent model of the Universe and other problems of cosmology and physics. ... And, of course, let's remember our recent tragic past.

   Academician Andrei Dmitrievich SAKHAROV (1921-1989).

   In Moscow in the 1970s and in Gorky, I continued my attempts to study physics and cosmology. During these years I was not able to put forward substantially new ideas, and I continued to develop those directions that were already presented in my works of the 60s (and described in the first part of this book). This is probably the lot of most scientists after they reach a certain age limit for them. However, I do not lose hope that, perhaps, something else will "flash" for me. At the same time, I must say that simply observing the scientific process, in which you yourself do not take part, but you know what's what, gives deep inner joy. In this sense, I am not “greedy”.

   In 1974 I did, and in 1975 I published a work in which I developed the idea of ​​the zero Lagrangian of the gravitational field, as well as the calculation methods that I used in previous works. At the same time, it turned out that I came to the method proposed many years ago by Vladimir Alexandrovich Fock, and then by Julian Schwinger. However, my conclusion and the way of construction itself, the methods were completely different. Unfortunately, I could not send my work to Fock - he died just then.

   Subsequently, I discovered some errors in my article. In it, the question remained unclear until the end whether "induced gravity" (the modern term used instead of the term "zero Lagrangian") gives the correct sign of the gravitational constant in any of the options that I considered.<...>

   Three papers - one published before my expulsion and two after my expulsion - are devoted to cosmological problems. In the first work, I discuss the mechanisms of the onset of baryon asymmetry. Of some interest, perhaps, are general considerations about the kinetics of reactions leading to the baryon asymmetry of the Universe. However, specifically in this work, I am reasoning within the framework of my old assumption about the presence of a "combined" conservation law (the sum of the numbers of quarks and leptons is preserved). I already wrote in the first part of my memoirs how I came to this idea and why I consider it wrong now. On the whole, this part of the work seems to me unsuccessful. Much more I like the part of the work where I write about multi-sheet model of the universe ... We are talking about the assumption that cosmological expansion of the Universe is replaced by contraction, then a new expansion in such a way that the cycles of contraction - expansion are repeated an infinite number of times... Such cosmological models have long attracted attention. Various authors have called them "Pulsating" or "Oscillating" models of the universe. I like the term better "Multi-sheet model" ... It seems more expressive, more in line with the emotional and philosophical meaning of the grandiose picture of the repeated repetition of the cycles of life.

   As long as conservation was assumed, the multivalent model met, however, with an insurmountable difficulty following from one of the fundamental laws of nature - the second law of thermodynamics.

   Retreat. In thermodynamics, a certain characteristic of the state of bodies is introduced, called. My dad once remembered an old popular science book called "The Queen of the World and Her Shadow." (Unfortunately, I forgot who the author of this book is.) The queen is, of course, energy, and the shadow is entropy. Unlike energy, for which there is a conservation law, for entropy the second law of thermodynamics establishes the law of increase (more precisely, non-decrease). Processes in which the total entropy of bodies does not change are called (considered) reversible. An example of a reversible process - mechanical movement without friction. Reversible processes are an abstraction, a limiting case of irreversible processes accompanied by an increase in the total entropy of bodies (during friction, heat exchange, etc.). Mathematically, entropy is defined as a value whose increment is equal to the heat inflow divided by the absolute temperature (additionally, it is taken - more precisely, it follows from general principles, - that the entropy at absolute zero temperature and the entropy of the vacuum are equal to zero).

   Numerical example for clarity. A body with a temperature of 200 degrees gives off 400 calories during heat exchange to a second body, which has a temperature of 100 degrees. The entropy of the first body has decreased by 400/200, i.e. by 2 units, and the entropy of the second body increased by 4 units; The total entropy has increased by 2 units, in accordance with the requirement of the second principle. Note that this result is a consequence of the fact that heat is transferred from a hotter body to a colder one.

   An increase in the total entropy during nonequilibrium processes ultimately leads to heating of the substance. Let's turn to cosmology, to multi-sheeted models. If in this case we assume the number of baryons to be fixed, then the entropy per baryon will increase indefinitely. The substance will heat up indefinitely with each cycle, i.e. conditions in the Universe will not be repeated!

   The difficulty is eliminated if we abandon the assumption of the conservation of the baryon charge and assume, in accordance with my idea of ​​1966 and its subsequent development by many other authors, that the baryon charge arises from "entropy" (i.e., neutral hot matter) in the early stages of the cosmological expansion of the universe. In this case, the number of produced baryons is proportional to the entropy at each expansion - contraction cycle, i.e. the conditions for the evolution of matter, the formation of structural forms can be approximately the same in each cycle.

   I first coined the term "multi-sheet model" in 1969 work. In my recent articles, I use the same term in a slightly different sense; I mention this here for the avoidance of confusion.

   In the first of the last three articles (1979), a model is considered in which the space is assumed to be flat on average. It is also assumed that Einstein's cosmological constant is not zero and negative (although it is very small in absolute value). In this case, as the equations of Einstein's theory of gravitation show, cosmological expansion is inevitably replaced by contraction. Moreover, each cycle completely repeats the previous one in terms of its average characteristics. It is essential that the model is spatially flat. Along with flat geometry (Euclidean geometry), the following two works are devoted to the consideration of the Lobachevsky geometry and the hypersphere geometry (a three-dimensional analogue of a two-dimensional sphere). In these cases, however, another problem arises. An increase in entropy leads to an increase in the radius of the Universe at the corresponding moments of each cycle. Extrapolating to the past, we find that each given cycle could be preceded by only a finite number of cycles.

   In "standard" (univalent) cosmology, there is a problem: what happened before the moment of maximum density? In many-sheeted cosmologies (except for the case of a spatially flat model), this problem cannot be avoided - the question is postponed to the moment of the beginning of the expansion of the first cycle. One can take the point of view that the beginning of the expansion of the first cycle, or, in the case of the standard model, the only cycle, is the Moment of the Creation of the World, and therefore the question of what happened before this is beyond the scope of scientific research. However, perhaps just as - or, in my opinion, more - an approach that allows unlimited Scientific research the material world and space - time. At the same time, apparently, there is no place for the Act of Creation, but the main religious concept of the divine meaning of Being is not affected by science, lies outside of it.

   I am aware of two alternative hypotheses related to the problem under discussion. One of them, it seems to me, was first expressed by me in 1966 and was subjected to a number of refinements in subsequent works. This is the "turn of the arrow of time" hypothesis. It is closely related to the so-called reversibility problem.

   As I already wrote, there are no completely reversible processes in nature. Friction, heat transfer, light emission, chemical reactions, life processes are characterized by irreversibility, a striking difference between the past and the future. If you shoot some kind of irreversible process and then start the movie in the opposite direction, then we will see on the screen something that cannot actually happen (for example, a flywheel rotating by inertia increases its speed of rotation, and the bearings are cooled). Quantitatively, irreversibility is expressed in a monotonic increase in entropy. At the same time, atoms, electrons, atomic nuclei, etc., which are part of all bodies. move according to the laws of mechanics (quantum, but this is insignificant here), which have complete reversibility in time (in quantum field theory - with simultaneous CP reflection, see the first part). The asymmetry of the two directions of time (the presence of the "arrow of time", as they say) with the symmetry of the equations of motion has long attracted the attention of the creators of statistical mechanics. Discussion of this issue began in the last decades of the last century and was sometimes quite stormy. The solution, which more or less satisfied everyone, consisted in the hypothesis that the asymmetry is due to the initial conditions of motion and the position of all atoms and fields "in the infinitely distant past." These initial conditions must be "random" in a certain sense.

   As I suggested (in 1966 and more explicitly in 1980), in cosmological theories that have a distinguished point in time, these random initial conditions not to the infinitely distant past (t -> - ∞), but to this distinguished point (t = 0).

   Then, automatically at this point, the entropy has a minimum value, and when moving away from it in time forward or backward, the entropy increases. This is what I have called the "turn of the arrow of time." Since when the arrow of time reverses, all processes, including information (including life processes), are reversed, no paradoxes arise. The above ideas about the reversal of the arrow of time, as far as I know, have not received recognition in the scientific world. But they seem interesting to me.

   The turn of the arrow of time restores the symmetry of the two directions of time in the cosmological picture of the world, inherent in the equations of motion!

   In 1966-1967. I assumed that CPT reflection occurs at the pivot point of the arrow of time. This assumption was one of the starting points of my work on baryon asymmetry. Here I will present another hypothesis (Kirzhnits, Linde, Gut, Turner and others had a hand; here I own only a remark that the arrow of time is turning).

   In modern theories, it is assumed that the vacuum can exist in various states: stable, with a high accuracy of zero energy density; and unstable, with a huge positive energy density (effective cosmological constant). The latter state is sometimes called "false vacuum".

   One of the solutions to the equations of general relativity for such theories is as follows. The universe is closed, i.e. at each moment is a "hypersphere" of a finite volume (a hypersphere is a three-dimensional analogue of a two-dimensional surface of a sphere; three-dimensional space). The radius of the hypersphere has a minimum finite value at a certain moment of time (denote it t = 0) and increases with distance from this point both forward and backward in time. The entropy is equal to zero for a false vacuum (as well as for any vacuum in general) and with distance from the point t = 0 forward or backward in time increases due to the decay of the false vacuum, passing into a stable state of the true vacuum. Thus, at the point t = 0, the arrow of time rotates (but there is no cosmological CPT symmetry, which requires infinite compression at the point of reflection). Just as in the case of CPT symmetry, all conserved charges here are also equal to zero (for a trivial reason - at t = 0, the vacuum state). Therefore, in this case, it is also necessary to assume the dynamic appearance of the observed baryon asymmetry due to violation of CP invariance.

   An alternative hypothesis about the prehistory of the Universe is that in fact there is not one Universe and not two (as - in a sense of the word - in the hypothesis of the rotation of the arrow of time), but a set of radically different from each other and arising from some "primary" space (or its constituent particles; this is perhaps just another way of expressing it). Other Universes and primary space, if it makes sense to talk about it, may, in particular, have, in comparison with “our” Universe, a different number of “macroscopic” spatial and temporal dimensions - coordinates (in our Universe there are three spatial and simultaneous dimensions; in other Universes may be different!) I ask you not to pay special attention to the adjective "macroscopic" enclosed in quotation marks. It is related to the “compactization” hypothesis, according to which most measurements are compactified; closed on itself on a very small scale.

   
   The structure of the "Mega-Universe"

   It is assumed that there is no causal relationship between different universes. This is what justifies their interpretation as separate universes. I call this grandiose structure "Mega Universe". Several authors have discussed variants of such hypotheses. In particular, the hypothesis of multiple birth of closed (approximately hyperspherical) Universes is defended by Ya.B. Zeldovich.

   The ideas of the Mega Universe are extremely interesting. Perhaps the truth lies precisely in this direction. For me, in some of these constructions, however, there is one ambiguity of a somewhat technical nature. It is quite acceptable to assume that the conditions in different areas of space are completely different. But the laws of nature must necessarily be the same everywhere and always. Nature cannot be like the Queen in Carroll's Alice in Wonderland, who arbitrarily changed the rules of the croquet game. Being is not a game. My doubts relate to those hypotheses that admit a break in the continuity of space-time. Are such processes permissible? Are they not a violation of the laws of nature at the points of rupture, and not the "conditions of being"? I repeat, I am not sure if these are legitimate concerns; maybe again, as in the question of the conservation of the number of fermions, I proceed from a too narrow point of view. In addition, hypotheses are quite conceivable where the birth of Universes occurs without disruption of continuity.

   The assumption that the birth of many, and perhaps an infinite number of different Universes occurs spontaneously, and that the Universe surrounding us is singled out among many worlds precisely by the condition for the emergence of life and mind, was called the "anthropic principle" (AP). Zeldovich writes that the first study of AP in the context of an expanding Universe known to him belongs to Idlis (1958). In the concept of a multi-sheeted universe, the anthropic principle can also play a role, but for the choice between successive cycles or their regions. This possibility is discussed in my work "Multivalent Models of the Universe". One of the difficulties of many-sheeted models is that the formation of "black holes" and their merging so breaks symmetry at the stage of compression that it is completely unclear whether the conditions of the next cycle are suitable for the formation of highly organized structures. On the other hand, in sufficiently long cycles, the processes of decay of baryons and evaporation of black holes occur, leading to the smoothing out of all density inhomogeneities. I suppose that the combined action of these two mechanisms - the formation of black holes and the leveling of irregularities - leads to the fact that there is a sequential change of smoother and more "disturbed" cycles. Our cycle is supposed to have been preceded by a "smooth" cycle during which no black holes were formed. For definiteness, we can consider a closed Universe with a "false" vacuum at the turning point of the arrow of time. The cosmological constant in this model can be considered equal to zero, the change of expansion by compression occurs simply due to the mutual attraction of ordinary matter. The duration of the cycles increases due to the growth of entropy at each cycle and exceeds any given number (tends to infinity), so that the conditions for the decay of protons and evaporation of "black holes" are satisfied.

   Multivariate models provide an answer to the so-called paradox of large numbers (another possible explanation is in the hypothesis of Guth et al, suggesting a long stage of "inflation", see Chapter 18).

   
   A planet on the outskirts of a distant globular star cluster. Artist © Don Dixon

   Why total number of protons and photons in a universe of finite volume is so immensely large, although of course? And another form of this question, referring to the "open" version - why is the number of particles so large in that region of the infinite world of Lobachevsky, the volume of which is of the order of A3 (A is the radius of curvature)?

   The answer given by the multi-sheet model is very simple. It is assumed that many cycles have passed since the moment t = 0, during each cycle the entropy (i.e., the number of photons) increased and, accordingly, an increasing baryon excess was generated in each cycle. The ratio of the number of baryons to the number of photons in each cycle is constant, since it is determined by the dynamics of the initial stages of the expansion of the Universe in a given cycle. The total number of cycles since the moment t = 0 is just such that the observed number of photons and baryons is obtained. Since the increase in their number occurs in geometric progression, then for the required number of cycles we get not even that great value.

   A side result of my work in 1982 is a formula for the probability of gravitational sticking together of black holes (using the estimate in the book by Zeldovich and Novikov).

   One more possibility, or rather a dream, which is intriguing to the imagination, is connected with multi-leaf models. Maybe a highly organized mind, evolving billions of billions of years during a cycle, finds a way to transmit in encoded form some of the most valuable piece of information it has to its heirs in the next cycles, separated from this cycle in time by a period of a superdense state? .. Analogy - transmission by living beings from generation to generation genetic information, "Compressed" and encoded in the chromosomes of the nucleus of a fertilized cell. This opportunity, of course, is absolutely fantastic, and I did not dare to write about it in scientific articles, but on the pages of this book gave himself free rein. But even regardless of this dream, the hypothesis of a multivalent model of the Universe seems to me important in the worldview philosophical plan.

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   Did you know that the universe we observe has fairly definite boundaries? We are used to associating the Universe with something infinite and incomprehensible. but modern science to the question of the "infinity" of the Universe offers a completely different answer to such an "obvious" question.

   According to modern concepts, the size of the observable universe is approximately 45.7 billion light years (or 14.6 gigaparsecs). But what do these numbers mean?

   The first question that comes to mind to an ordinary person- how the Universe cannot be infinite at all? It would seem indisputable that the container of everything that exists around us should have no boundaries. If these boundaries exist, what are they?

   Let's say some astronaut flew to the borders of the universe. What will he see in front of him? A solid wall? Fire barrier? And what is behind it - emptiness? Another Universe? But can emptiness or another Universe mean that we are on the border of the universe? After all, this does not mean that there is "nothing". The emptiness and the other Universe are also “something”. But the Universe is something that contains absolutely everything “something”.

   We come to an absolute contradiction. It turns out that the border of the Universe should hide from us something that should not be. Or the border of the Universe should fence off “everything” from “something”, but this “something” should also be a part of “everything”. In general, a complete absurdity. Then how can scientists claim the limiting size, mass, and even age of our universe? These values, although unimaginably large, are still finite. Is science arguing with the obvious? To deal with this, let's first trace how humans came to a modern understanding of the universe.

   Expanding the boundaries

   

   From time immemorial, man has been interested in what the world around them is. One need not give examples of the three whales and other attempts of the ancients to explain the universe. As a rule, in the end it all came down to the fact that the foundation of all that exists is the earthly firmament. Even in antiquity and the Middle Ages, when astronomers had extensive knowledge of the laws governing the motion of planets along the "stationary" celestial sphere, the Earth remained the center of the Universe.

   Naturally, even in Ancient Greece there were those who believed that the Earth revolved around the Sun. There were those who spoke about the many worlds and the infinity of the universe. But constructive justification for these theories emerged only at the turn of the scientific revolution.

   In the 16th century, the Polish astronomer Nicolaus Copernicus made the first major breakthrough in the knowledge of the Universe. He firmly proved that the Earth is only one of the planets orbiting the Sun. Such a system greatly simplified the explanation of such a complex and intricate movement of the planets in the celestial sphere. In the case of a stationary Earth, astronomers had to invent all sorts of ingenious theories to explain this behavior of the planets. On the other hand, if the Earth is taken to be mobile, then the explanation for such intricate movements comes naturally. This is how a new paradigm called "heliocentrism" became established in astronomy.

   Many Suns

   

   However, even after that, astronomers continued to confine the universe to the "sphere of fixed stars." Until the 19th century, they could not estimate the distance to the stars. For several centuries, astronomers unsuccessfully tried to detect deviations in the position of stars relative to the Earth's orbital motion ( annual parallaxes). The instruments of those times did not allow such accurate measurements.

   Finally, in 1837, the Russian-German astronomer Vasily Struve measured the parallax. This marked a new step in understanding the scale of space. Now scientists could safely say that the stars are distant similarities to the Sun. And from now on our luminary is not the center of everything, but an equal "inhabitant" of the endless star cluster.

   Astronomers have come even closer to understanding the scale of the Universe, because the distances to the stars turned out to be truly monstrous. Even the size of the orbits of the planets seemed insignificant in comparison with this. Next, it was necessary to understand how the stars are concentrated in.

   Many Milky Way

   

   The famous philosopher Immanuel Kant anticipated the foundations of the modern understanding of the large-scale structure of the Universe back in 1755. He hypothesized that the Milky Way is a huge rotating cluster of stars. In turn, many of the observed nebulae are also more distant "milky ways" - galaxies. Despite this, until the 20th century, astronomers adhered to the fact that all nebulae are sources of star formation and are part of the Milky Way.

   The situation changed when astronomers learned to measure distances between galaxies using. The absolute luminosity of stars of this type is strictly dependent on the period of their variability. Comparing their absolute luminosity with the visible one, it is possible to determine the distance to them with high accuracy. This method was developed in the early 20th century by Einar Herzsrung and Harlow Shelpy. Thanks to him, the Soviet astronomer Ernst Epik in 1922 determined the distance to Andromeda, which turned out to be an order of magnitude larger than the size of the Milky Way.

   Edwin Hubble continued Epic's endeavor. By measuring the brightness of Cepheids in other galaxies, he measured the distance to them and compared it with the redshift in their spectra. So in 1929 he developed his famous law. His work has definitively refuted the entrenched notion that the Milky Way is the edge of the universe. It was now one of many galaxies that had once been considered an integral part of it. Kant's hypothesis was confirmed almost two centuries after its development.

   Later, the connection between the distance of the galaxy from the observer and the speed of its removal from the observer, discovered by Hubble, made it possible to compose a full-fledged picture of the large-scale structure of the Universe. It turned out that the galaxies were only an insignificant part of it. They linked into clusters, clusters into superclusters. In turn, superclusters fold into the largest known structures in the universe - filaments and walls. These structures, adjacent to huge supervoids (), make up a large-scale structure known in this moment, The universe.

   Apparent infinity

   From the above, it follows that in just a few centuries, science has gradually leapt from geocentrism to the modern understanding of the Universe. However, this does not provide an answer as to why we are limiting the Universe these days. After all, until now it was only about the scale of the cosmos, and not about its very nature.

   

   The first who decided to substantiate the infinity of the Universe was Isaac Newton. Having discovered the law of universal gravitation, he believed that if space were finite, all her bodies would sooner or later merge into a single whole. Before him, if someone expressed the idea of ​​the infinity of the Universe, it was exclusively in a philosophical vein. Without any scientific justification. An example of this is Giordano Bruno. By the way, like Kant, he was ahead of science by many centuries. He was the first to declare that the stars are distant suns, and planets also revolve around them.

   It would seem that the very fact of infinity is quite justified and obvious, but the turning points of science of the 20th century shook this "truth."

   Stationary universe

   The first significant step towards the development of a modern model of the Universe was made by Albert Einstein. The famous physicist introduced his model of a stationary universe in 1917. This model was based on the general theory of relativity, which he developed the same year earlier. According to his model, the universe is infinite in time and finite in space. But after all, as noted earlier, according to Newton, a universe with a finite size should collapse. To do this, Einstein introduced a cosmological constant, which compensated for the gravitational attraction of distant objects.

   As paradoxical as it may sound, Einstein did not limit the very finiteness of the universe. In his opinion, the Universe is a closed shell of a hypersphere. An analogy is the surface of an ordinary three-dimensional sphere, for example, a globe or the Earth. No matter how much a traveler travels around the Earth, he will never reach its edge. However, this does not mean at all that the Earth is infinite. The traveler will simply return to the place where he started his journey.

   On the surface of the hypersphere

   Likewise, a space wanderer, overcoming Einstein's Universe on a starship, can return back to Earth. Only this time the wanderer will move not along the two-dimensional surface of the sphere, but along the three-dimensional surface of the hypersphere. This means that the Universe has a finite volume, and hence a finite number of stars and mass. However, the Universe has no boundaries or any center.

   

   Einstein came to such conclusions by linking space, time and gravity in his famous theory. Before him, these concepts were considered separate, which is why the space of the Universe was purely Euclidean. Einstein proved that gravity itself is a curvature of spacetime. This radically changed the early ideas about the nature of the Universe, based on classical Newtonian mechanics and Euclidean geometry.

   Expanding Universe

   Even the discoverer of the "new Universe" himself was no stranger to delusion. Although Einstein limited the universe in space, he continued to consider it static. According to his model, the universe was and remains eternal, and its size always remains the same. In 1922, the Soviet physicist Alexander Fridman significantly expanded this model. According to his calculations, the universe is not static at all. It can expand or contract over time. It is noteworthy that Friedman came to such a model, based on the same theory of relativity. He was able to more correctly apply this theory, bypassing the cosmological constant.

   Albert Einstein did not immediately accept this "amendment". The Hubble discovery mentioned earlier came to the rescue of this new model. The scattering of galaxies indisputably proved the fact of the expansion of the Universe. So Einstein had to admit his mistake. Now the Universe had a certain age, which strictly depends on the Hubble constant, which characterizes the rate of its expansion.

   Further development of cosmology

   As scientists tried to solve this issue, many other important components of the Universe were discovered and various models of it were developed. So in 1948 Georgy Gamow introduced the hypothesis "about a hot Universe", which would later turn into the theory of the big bang. The discovery in 1965 confirmed his guesses. Now astronomers could observe the light that has come down from the moment the universe became transparent.

   Dark matter, predicted in 1932 by Fritz Zwicky, was confirmed in 1975. Dark matter actually explains the very existence of galaxies, galactic clusters and the Universe itself as a whole. So scientists learned that most of the mass of the Universe is completely invisible.

   

   Finally, in 1998, during a study of the distance to, it was discovered that the universe is expanding with acceleration. This next turning point in science gave rise to the modern understanding of the nature of the universe. The cosmological coefficient, introduced by Einstein and refuted by Friedman, has again found its place in the model of the Universe. The presence of the cosmological coefficient (cosmological constant) explains its accelerated expansion. To explain the presence of the cosmological constant, the concept was introduced - a hypothetical field containing most of the mass of the Universe.

   Current understanding of the size of the observable universe

   The current model of the universe is also called the ΛCDM model. The letter "Λ" denotes the presence of a cosmological constant that explains the accelerated expansion of the Universe. "CDM" means that the universe is filled with cold dark matter. Recent studies indicate that the Hubble constant is about 71 (km / s) / Mpc, which corresponds to the age of the Universe 13.75 billion years. Knowing the age of the Universe, one can estimate the size of its observable area.

   

   According to the theory of relativity, information about any object cannot reach the observer with a speed greater than the speed of light (299792458 m / s). It turns out that the observer sees not just an object, but its past. The further the object is from it, the more distant past it looks. For example, looking at the Moon, we see the way it was a little more than a second ago, the Sun - more than eight minutes ago, the nearest stars - years, galaxies - millions of years ago, etc. In Einstein's stationary model, the Universe has no age limit, which means that its observable region is also unlimited. The observer, armed with more and more advanced astronomical instruments, will observe more and more distant and ancient objects.

   We have a different picture with the modern model of the Universe. According to it, the Universe has an age, and therefore a limit of observation. That is, since the birth of the Universe, no photon would have had time to travel a distance greater than 13.75 billion light years. It turns out that we can state that the observable Universe is limited from the observer by a spherical region with a radius of 13.75 billion light years. However, this is not quite true. Do not forget about the expansion of the space of the Universe. Until the photon reaches the observer, the object that emitted it will be 45.7 billion sv from us. years. This size is the horizon of particles, and it is the boundary of the observable Universe.

   Over the horizon

   So, the size of the observable Universe is divided into two types. Visible size, also called the Hubble radius (13.75 billion light years). And the real size, called the particle horizon (45.7 billion light years). It is important that both of these horizons do not at all characterize the real size of the Universe. First, they depend on the position of the observer in space. Second, they change over time. In the case of the ΛCDM model, the particle horizon expands at a speed greater than the Hubble horizon. The question of whether this trend will change in the future, modern science does not give an answer. But if we assume that the Universe will continue to expand with acceleration, then all those objects that we see now, sooner or later, will disappear from our “field of view”.

   At the moment, the most distant light observed by astronomers is the microwave background radiation. Peering into it, scientists see the Universe as it was 380 thousand years after the Big Bang. At that moment, the Universe cooled down so much that it was able to emit free photons, which are captured today with the help of radio telescopes. In those days, there were no stars or galaxies in the Universe, but only a continuous cloud of hydrogen, helium and an insignificant amount of other elements. From the inhomogeneities observed in this cloud, galactic clusters will subsequently form. It turns out that exactly those objects that are formed from the inhomogeneities of the relict radiation are located closest to the particle horizon.

   True boundaries

   Whether the universe has true, unobservable boundaries is still the subject of pseudoscientific conjectures. One way or another, everyone converges at the infinity of the Universe, but they interpret this infinity in completely different ways. Some consider the Universe to be multidimensional, where our “local” three-dimensional Universe is only one of its layers. Others say that the universe is fractal - which means that our local universe may turn out to be a particle of another. Do not forget about the various models of the Multiverse with its closed, open, parallel Universes, wormholes. And there are many, many different versions, the number of which is limited only by human imagination.

   But if we turn on cold realism or simply move away from all these hypotheses, then we can assume that our Universe is an infinite homogeneous repository of all stars and galaxies. Moreover, at any very distant point, be it billions of gigaparsecs from us, all conditions will be exactly the same. At this point, there will be exactly the same horizon of particles and the Hubble sphere with the same relic radiation at their edge. There will be the same stars and galaxies around. Interestingly, this does not contradict the expansion of the universe. After all, it is not just the Universe that is expanding, but its very space. The fact that at the moment of the big bang the Universe arose from one point only says that the infinitely small (practically zero) sizes that were then have now turned into unimaginably large ones. In the future, we will use this particular hypothesis in order to clearly understand the scale of the observable Universe.

   Visual representation

   Various sources provide all kinds of visual models that allow people to understand the scale of the Universe. However, it is not enough for us to realize how big the cosmos is. It is important to understand how concepts such as the Hubble horizon and the particle horizon actually manifest. To do this, let's imagine our model step by step.

   Let's forget that modern science does not know about the "foreign" region of the Universe. Discarding the versions about the multiverse, the fractal Universe and its other "varieties", imagine that it is simply infinite. As noted earlier, this does not contradict the expansion of her space. Of course, we will take into account the fact that its Hubble sphere and the sphere of particles are respectively equal to 13.75 and 45.7 billion light years.

   The scale of the universe

   Press the START button and discover a new, unknown world!
   To begin with, let's try to realize how large the universal scale is. If you have traveled around our planet, then you can well imagine how big the Earth is for us. Now let's imagine our planet as a buckwheat grain that orbits around a watermelon-Sun half the size of a football field. In this case, the orbit of Neptune will correspond to the size of a small city, the area to the Moon, the area of ​​the Sun's influence boundary to Mars. It turns out that our Solar System is as much larger than the Earth as Mars is larger than buckwheat! But this is just the beginning.

   Now let's imagine that this buckwheat will be our system, the size of which is approximately equal to one parsec. Then the Milky Way will be the size of two football stadiums. However, even this will not be enough for us. We'll have to reduce the Milky Way to a centimeter size. It will somewhat resemble coffee foam wrapped in a whirlpool in the middle of the coffee-black intergalactic space. Twenty centimeters away from it there is the same spiral "crumb" - the Andromeda Nebula. Around them will be a swarm of small galaxies from our Local Cluster. The apparent size of our universe will be 9.2 kilometers. We have come to an understanding of the Universal dimensions.

   Inside the universal bubble

   However, it is not enough for us to understand the scale itself. It is important to understand the dynamics of the universe. Let's imagine ourselves as giants, for which the Milky Way has a centimeter diameter. As noted just now, we will find ourselves inside a ball with a radius of 4.57 and a diameter of 9.24 kilometers. Imagine that we are able to hover inside this sphere, travel, overcoming entire megaparsecs in a second. What will we see if our Universe is infinite?

   Of course, before us there will be an infinite number of all kinds of galaxies. Elliptical, spiral, irregular. Some areas will be teeming with them, others will be empty. The main feature will be that visually they will all be motionless while we are motionless. But as soon as we take a step, the galaxies themselves will begin to move. For example, if we are able to discern the microscopic Solar System in the centimeter Milky Way, we will be able to observe its development. Moving 600 meters away from our galaxy, we will see the protostar Sun and the protoplanetary disk at the time of formation. Approaching it, we will see how the Earth appears, life is born and a person appears. In the same way, we will see how galaxies change and move as we move away or approach them.

   Therefore, the more distant galaxies we look, the more ancient they will be for us. So the most distant galaxies will be located further than 1300 meters from us, and at the turn of 1380 meters we will see the relic radiation. True, this distance will be imaginary for us. However, as we get closer to the relic radiation, we will see an interesting picture. Naturally, we will observe how galaxies will form and develop from the original cloud of hydrogen. When we reach one of these formed galaxies, we will realize that we have overcome not 1.375 kilometers at all, but all 4.57.

   Downscaling

   As a result, we will increase even more in size. Now we can place whole voids and walls in the fist. So we find ourselves in a rather small bubble, from which it is impossible to get out. Not only will the distance to objects on the edge of the bubble increase as they get closer, but the edge itself will drift infinitely. This is the whole point of the size of the observable universe.

   No matter how big the Universe is, for the observer it will always remain a limited bubble. The observer will always be in the center of this bubble, in fact, he is its center. Trying to get to any object at the edge of the bubble, the observer will shift its center. As it gets closer to the object, this object will move farther and farther from the edge of the bubble and at the same time change. For example, from a shapeless hydrogen cloud it will turn into a full-fledged galaxy or further a galaxy cluster. In addition, the path to this object will increase as you approach it, as the surrounding space itself will change. Once we get to this object, we will only move it from the edge of the bubble to its center. At the edge of the Universe, the relic radiation will also flicker.

   If we assume that the Universe will continue to expand at an accelerated rate, then being in the center of the bubble and winding time for billions, trillions and even higher orders of years ahead, we will notice an even more interesting picture. Although our bubble will also grow in size, its mutating components will move away from us even faster, leaving the edge of this bubble, until each particle of the universe wanders scattered in its lonely bubble without the ability to interact with other particles.

   So, modern science does not have information about what the real dimensions of the Universe are and whether it has boundaries. But we know for sure that the observed Universe has a visible and true border, called the Hubble radius (13.75 billion light years) and the radius of particles (45.7 billion light years), respectively. These boundaries are completely dependent on the position of the observer in space and expand over time. If the Hubble radius expands strictly at the speed of light, then the expansion of the particle horizon is accelerated. The question of whether its acceleration of the particle horizon will continue further and will not change to compression remains open.
   

   COSMOLOGY- the section of astronomy and astrophysics, which studies the origin, large-scale structure and evolution of the Universe. The data for cosmology are mainly obtained from astronomical observations. Einstein's general theory of relativity (1915) is currently used for their interpretation. The creation of this theory and the implementation of the corresponding observations made it possible in the early 1920s to place cosmology in a number of exact sciences, whereas before that it was rather a field of philosophy. Two cosmological schools have now emerged: empiricists confine themselves to interpreting observational data without extrapolating their models to unexplored areas; theorists try to explain the observable universe using some hypotheses selected for simplicity and elegance. The cosmological model of the Big Bang is now widely known, according to which the expansion of the Universe began some time ago from a very dense and hot state; stationarya model of the Universe in which it exists eternally and has no beginning or end. COSMOLOGICAL DATA

   Cosmological data mean the results of experimentsand observations related to the universe as a whole in a wide range of space and time. Any conceivable cosmological model must satisfy these data. There are 6 main observational facts that cosmology should explain:

   1. On a large scale, the Universe is homogeneous and isotropic; galaxies and their clusters are distributed in space evenly (uniformly), and their movement is chaotic and does not have a clearly defined direction (isotropic). The Copernican principle, "moving the Earth from the center of the world," was generalized by astronomers to the solar system and our Galaxy, which also turned out to be quite ordinary. Therefore, excluding small irregularities in the distribution of galaxies and their clusters, astronomers consider the Universe to be as homogeneous everywhere as it is near us.

   2. The universe is expanding. Galaxies are moving away from each other.

   This was discovered by the American astronomer E. Hubble in 1929. Hubble's law says: the farther a galaxy is, the faster it moves away from us.But this does not mean that we are in the center of the universe: in any other galaxy, observers see the same thing. With the help of new telescopes, astronomers have delved into the Universe much farther than Hubble, but his law has remained true.

   3. Space around the Earth is filled with background microwave

   radio emission. Discovered in 1965, it became, along with galaxies, the main object of cosmology. Its important property is its high isotropy (independence from direction), which indicates its connection with distant regions of the Universe and confirms their high homogeneity. If it were the radiation of our Galaxy, then it would reflect its structure. But experiments on balloons and satellites proved that this radiation in the highest degree is homogeneous and has a spectrum of radiation of an absolutely black body with a temperature of about 3 K. Obviously, this is the relic radiation of a young and hot Universe, which has cooled greatly as a result of its expansion.

   4. The age of the Earth, meteorites and the oldest stars are few

   less than the age of the Universe, calculated from the rate of its expansion.In accordance with Hubble's law, the universe expands everywhere at the same rate, which is called the Hubble constant H... It can be used to estimate the age of the Universe as 1 / H... Modern measurements H lead to the age of the universe approx. 20 billion years. Studies of radioactive decay products in meteorites give an age of approx. 10 billion years old, and the oldest stars are ca. 15 billion years. Until 1950, distances to galaxies were underestimated, leading to an overestimate H and the small age of the Universe, less than the age of the Earth. To resolve this contradiction, G. Bondy, T. Gold and F. Hoyle in 1948 proposed a stationary cosmological model in which the age of the Universe is infinite, and as it expands, new matter is born.

   5. In the entire observable Universe, from nearby stars to the most distant galaxies, for every 10 hydrogen atoms there is 1 atom of helium. It seems incredible that the local conditions would be so similar everywhere. The strength of the Big Bang model is that it predicts the same ratio between helium and hydrogen everywhere.

   6. In the regions of the Universe, remote from us in space and time, there are more active galaxies and quasars than near us. This indicates the evolution of the universe and contradicts the theory of a stationary universe.

   COSMOLOGICAL MODELS

   Any cosmological model of the Universe is based on a specific theory of gravity. There are many such theories, but only a few of them satisfy the observed phenomena. Newton's theory of gravitation does not satisfy them even within the solar system. Einstein's general theory of relativity, on the basis of which the Russian meteorologist A. Friedman in 1922 and the Belgian abbot and mathematician J. Lemaitre in 1927, mathematically described the expansion of the Universe, agrees best with observations. From the cosmological principle that postulates the spatial homogeneity and isotropy of the world, they obtained the Big Bang model. Their conclusion was confirmed when Hubble discovered the relationship between the distance and the speed of the retreat of galaxies. The second important prediction of this model, made by G. Gamov, concerned the relic radiation, which is now observed as a remnant of the Big Bang. Other cosmological models cannot naturally explain this isotropic background radiation.Hot Big Bang. According to the Friedmann-Lemaitre cosmological model, the Universe arose at the time of the Big Bang - approx. 20 billion years ago, and its expansion continues to this day, gradually slowing down. In the first instant of the explosion, the matter of the Universe had infinite density and temperature; this state is called a singularity.

   According to general relativity, gravity is not a real force, but a curvature of space-time: the greater the density of matter, the stronger the curvature. At the moment of the initial singularity, the curvature was also infinite. You can express the infinite curvature of space-time in other words, saying that at the initial moment, matter and space exploded simultaneously everywhere in the Universe. As the volume of space of the expanding Universe increases, the density of matter in it decreases. S. Hawking and R. Penrose proved that in the past there was certainly a singular state, if the general theory of relativity is applicable to describe physical processes in the very early Universe.

   To avoid a catastrophic singularity in the past, it is necessary to significantly change physics, for example, by assuming the possibility of spontaneous continuous creation of matter, as in the theory of a stationary universe. But astronomical observations do not provide any basis for this.

   The earlier events we consider, the smaller their spatial scale was; as one approaches the beginning of the expansion, the observer's horizon contracts (Fig. 1). In the very first moments, the scale is so small that we no longer have the right to apply general relativity: quantum mechanics is required to describe phenomena on such small scales. (cm... QUANTUM MECHANICS)... But the quantum theory of gravity does not yet exist, so no one knows how events developed until the moment 10

   –43 with called Planck time(in honor of the father of quantum theory). At that moment, the density of matter reached an incredible value of 10 90 kg / cm 3 , which cannot be compared not only with the density of the bodies around us (less than 10 g / cm 3 ), but even with the density of the atomic nucleus (about 10 12 kg / cm 3 ) - the highest density available in the laboratory. Therefore, for modern physics, the beginning of the expansion of the Universe is the Planck time.

   It was under such conditions of inconceivably high temperature and density that the birth of the Universe took place. Moreover, this could be a birth in the literal sense: some cosmologists (say, Ya.B. Zeldovich in the USSR and L. Parker in the USA) believed that particles and gamma photons were born in that era by the gravitational field. From the point of view of physics, this process could take place if the singularity was anisotropic, i.e. the gravitational field was inhomogeneous. In this case, tidal gravitational forces could "pull" real particles out of the vacuum, thus creating the substance of the Universe.

   Studying the processes that took place immediately after the Big Bang, we understand that our physical theories are still very imperfect. The thermal evolution of the early Universe depends on the production of massive elementary particles - hadrons, about which nuclear physics still knows little. Many of these particles are unstable and short-lived. The Swiss physicist R. Hagedorn believes that there may be a great many hadrons of increasing masses, which could be formed in abundance at temperatures of the order of 10

   12 K, when the giant radiation density led to the production of hadron pairs consisting of a particle and an antiparticle. This process would have to limit the rise in temperature in the past.

   According to another point of view, the number of types of massive elementary particles is limited, so the temperature and density during the hadron era had to reach infinite values. In principle, this could be verified: if the constituent hadrons - quarks - were stable particles, then a certain number of quarks and antiquarks should have survived from that hot era. But the search for quarks was in vain; they are most likely unstable. Cm . See also ELEMENTARY PARTICLES.

   After the first millisecond of the expansion of the Universe, the strong (nuclear) interaction ceased to play a decisive role in it: the temperature dropped so much that atomic nuclei ceased to be destroyed. Further physical processes were determined by the weak interaction responsible for the production of light particles - leptons (i.e. electrons, positrons, mesons and neutrinos) under the influence of thermal radiation. When, during the expansion, the radiation temperature dropped to about 10

   10 K, lepton pairs have ceased to be produced, almost all positrons and electrons have annihilated; there were only neutrinos and antineutrinos, photons and a few protons and neutrons preserved from the previous epoch. Thus ended the lepton era.

   The next phase of expansion - the photon era - is characterized by the absolute predominance of thermal radiation. For every proton or electron that remains, there are a billion photons. At first, these were gamma quanta, but as the Universe expanded, they lost energy and became X-ray, ultraviolet, optical, infrared and, finally, now they have become radio quanta, which we take as blackbody background (relic) radio emission.

   Unsolved problems of the Big Bang cosmology. There are 4 problems that are now facing the cosmological model of the Big Bang.

   1. The singularity problem: many question the applicability of general relativity, which gives a singularity in the past. Alternative cosmological theories free of singularity are proposed.

   2. Closely related to the singularity is the problem of the isotropy of the Universe. It seems strange that the expansion, which began with a singular state, turned out to be so isotropic. It is not excluded, however, that the initially anisotropic expansion gradually became isotropic under the action of dissipative forces.

   3. Homogeneous on the largest scales, on smaller scales, the Universe is very heterogeneous (galaxies, clusters of galaxies). It is difficult to understand how gravity alone could have produced such a structure. Therefore, cosmologists are studying the possibilities of inhomogeneous models of the Big Bang.

   4. Finally, one may ask, what is the future of the universe? To answer, you need to know the average density of matter in the Universe. If it exceeds a certain critical value, then the geometry of space-time is closed, and in the future the Universe will certainly shrink. The closed Universe has no boundaries, but its volume is finite. If the density is below critical, then the Universe is open and will expand forever. The open universe is infinite and has only one singularity at the beginning. So far, the observations are in better agreement with the open universe model.

   The origin of the large-scale structure. Cosmologists have two opposite points of view on this problem.

   The most radical is that in the beginning there was chaos. The expansion of the early Universe was extremely anisotropic and inhomogeneous, but then dissipative processes smoothed out the anisotropy and brought the expansion closer to the Friedmann-Lemaitre model. The fate of the inhomogeneities is very curious: if their amplitude was large, then inevitably they should have collapsed into black holes with a mass determined by the current horizon. Their formation could have started right from the Planck time, so there could be many small black holes in the Universe with masses up to 10

   –5 However, S. Hawking showed that "mini-holes" should, by emitting, lose their mass, and until our epoch only black holes with masses of more than 10 16 g, which corresponds to the mass of a small mountain. Cm . See also BLACK HOLE.

   Primary chaos could contain disturbances of any scale and amplitude; the largest of them in the form of sound waves could have survived from the era of the early Universe to the era of radiation, when matter was still hot enough to emit, absorb and scatter radiation. But with the end of this era, the cooled plasma recombined and stopped interacting with radiation. The pressure and speed of sound in the gas dropped, causing the sound waves to turn into shock waves, compressing the gas and causing it to collapse into galaxies and clusters. Depending on the type of initial waves, the calculations predict a very different picture, which does not always correspond to the observed one. One philosophical idea, known as the anthropic principle, is important for choosing between possible variants of cosmological models: from the very beginning, the Universe should have had such properties that allowed galaxies, stars, planets and intelligent life to form in it. Otherwise, there would be no one to deal with cosmology.

   An alternative point of view is that nothing more can be learned about the original structure of the universe than what observations give. According to this conservative approach, the young universe cannot be considered chaotic, since it is now very isotropic and homogeneous. The deviations from uniformity that we observe in the form of galaxies could have grown under the influence of gravity from small initial density irregularities. However, studies of the large-scale distribution of galaxies (mainly by J. Peebles at Princeton) do not seem to support this idea. Another interesting possibility is that clusters of black holes born in the hadronic era could have been the initial fluctuations for the formation of galaxies.

   Is the Universe open or closed? The nearest galaxies are moving away from us at a speed proportional to the distance; but the more distant ones do not obey this dependence: their movement indicates that the expansion of the Universe is slowing down with time. In a closed model of the Universe under the action of gravity, expansion at a certain moment stops and is replaced by contraction (Fig. 2), but observations show that the deceleration of galaxies is still not so fast that a complete stop ever occurs.

   For the Universe to be closed, the average density of matter in it must exceed a certain critical value. The density estimates for visible and invisible matter are very close to this value.

   The distribution of galaxies in space is very heterogeneous. Our Local Group of galaxies, which includes the Milky Way, the Andromeda Nebula and several smaller galaxies, lies on the periphery of a vast galaxy system known as the Virgo Supercluster, whose center coincides with the Virgo cluster of galaxies. If the average density of the world is high and the Universe is closed, then a strong deviation from isotropic expansion should be observed, caused by the attraction of our and neighboring galaxies to the center of the Supercluster. In an open universe, this deviation is insignificant. The observations are rather consistent with the open model.

   Of great interest to cosmologists is the content of the heavy isotope of hydrogen, deuterium, in cosmic matter, which was formed in the course of nuclear reactions in the first moments after the Big Bang. The deuterium content turned out to be extremely sensitive to the density of matter in that era, and therefore in ours. However, the "deuterium test" is not easy to carry out, because it is necessary to investigate the primary matter, which has not been in the interiors of stars since the moment of cosmological synthesis, where deuterium easily burns up. The study of extremely distant galaxies has shown that the deuterium content corresponds to the low density of matter and, therefore, to the open model of the Universe.

   Alternative cosmological models. Generally speaking, at the very beginning of its existence, the Universe could be very chaotic and heterogeneous; traces of this we may observe today in the large-scale distribution of matter. However, the period of chaos could not last long. The high homogeneity of the cosmic background radiation indicates that the Universe was very homogeneous at the age of 1 million years. And calculations of cosmological nuclear fusion indicate that if after 1 s after the beginning of the expansion there were large deviations from the standard model, then the composition of the Universe would be completely different than in reality. However, what happened during the first second is still debatable. In addition to the standard Big Bang model, in principle, there are alternative cosmological models:

   1. The model, symmetric with respect to matter and antimatter, assumes the equal presence of these two types of matter in the Universe. Although it is obvious that our Galaxy contains practically no antimatter, neighboring stellar systems could well consist entirely of it; in this case, their radiation would be exactly the same as that of normal galaxies. However, in earlier epochs of expansion, when matter and antimatter were in closer contact, their annihilation should have produced powerful gamma rays. Observations do not detect it, which makes a symmetric model unlikely.

   2. The Cold Big Bang model assumes that the expansion began at absolute zero. True, in this case, nuclear fusion must also occur and heat the substance, but the microwave background radiation can no longer be directly associated with the Big Bang, but must be explained in some other way. This theory is attractive because the matter in it is subject to fragmentation, which is necessary to explain the large-scale inhomogeneity of the Universe.

   3. The stationary cosmological model assumes the continuous creation of matter. The basic premise of this theory, known as the Ideal Cosmological Principle, states that the universe has always been and will remain as it is today. Observations refute this.

   4. Modified versions of Einstein's theory of gravity are considered. For example, the theory of K. Bruns and R. Dicke from Princeton generally agrees with observations within the solar system. The Brans - Dicke model, as well as the more radical Hoyle model, in which some fundamental constants change over time, have almost the same cosmological parameters in our era as the Big Bang model.

   5. On the basis of the modified Einstein theory, J. Lemaître in 1925 built a cosmological model that combines the Big Bang with a long phase of a quiet state, during which galaxies could form. Einstein became interested in this opportunity to substantiate his favorite cosmological model of a static universe, but when the expansion of the universe was discovered, he publicly abandoned it.

   In 1917 A. Einstein built a model of the Universe. In this model, a cosmological repulsive force called the lambda parameter was used to overcome the gravitational instability of the Universe. In the future, Einstein will say that this was his gross mistake, contrary to the spirit of the theory of relativity that he created: the force of gravity in this theory is identified with the curvature of space-time. Einstein's universe had the shape of a hypercylinder, the length of which was determined by the total number and composition of forms of manifestation of energy (matter, field, radiation, vacuum) in this cylinder. Time in this model is directed from the endless past to the endless future. Thus, here the value of the energy, mass of the Universe (matter, field, radiation, vacuum) is proportionally related to its spatial structure: limited in its shape, but infinite radius and infinite in time.

   Researchers who began to analyze this model drew attention

   to its extreme instability, similar to a coin standing on an edge, one side of which corresponds to an expanding Universe, the other to a closed one: when some physical parameters of the Universe are taken into account, according to Einstein's model, it turns out to be eternally expanding, when others are taken into account, it is closed. For example, the Dutch astronomer W. de Sitter, assuming that time is curved in the same way as space in Einstein's model, received a model of the Universe, in which time completely stops in very distant objects.

   A. Freedman,fandsuk and mathematician of Petrograd University, publishedv1922 G. article« Ocurvaturespace ".V She presented the results of studies of the general theory of relativity, which did not exclude the mathematical possibility of the existence of three models of the Universe: the model of the Universe in Euclidean space ( TO = 0); model with a coefficient equal to ( K> 0) and a model in the Lobachevsky - Bolyai space ( TO< 0).

   In his calculations A. Friedman proceeded from the assumption that the value and

   the radius of the Universe is proportional to the amount of energy, matter and other

   forms of its manifestation in the Universe as a whole. A. Friedman's mathematical conclusions denied the need to introduce the cosmological repulsive force, since the general theory of relativity did not exclude the possibility of the existence of a model of the Universe, in which the process of its expansion corresponds to the process of compression associated with an increase in the density, pressure of the energy-matter constituting the Universe (matter, field, radiation , vacuum). A. Friedman's conclusions have caused doubts among many scientists and A. Einstein himself. Although already in 1908 the mathematician G. Minkowski, having given a geometric interpretation of the special theory of relativity, received a model of the Universe in which the curvature coefficient is equal to zero ( TO = 0), i.e., the model of the Universe in Euclidean space.

   N. Lobachevsky, the founder of non-Euclidean geometry, measured the angles of a triangle between stars distant from the Earth and found that the sum of the angles of a triangle is 180 °, that is, space in space is Euclidean. The observed Euclidean space of the Universe is one of the mysteries of modern cosmology. It is currently believed that the density of matter

   in the Universe is 0.1-0.2 parts of the critical density. The critical density is approximately equal to 2 · 10 -29 g / cm 3. Having reached a critical density, the universe will begin to shrink.

   A. Friedman's model with "TO > 0 "is an expanding Universe from the original

   her condition, to which she must return again. In this model, the concept of the age of the Universe appeared: the presence of a previous state relative to that observed at a certain moment.

   Assuming that the mass of the entire universe is 5 10 2 1 solar masses, A.

   Friedman calculated that the observable universe was in a compressed state

   according to the model " K > 0 "approximately 10-12 billion years ago. After that, it began to expand, but this expansion will not be infinite, and after a certain time, the Universe will contract again. A. Friedman refused to discuss the physics of the initial, compressed state of the Universe, since the laws of the microworld were not clear by that time. A. Fridman's mathematical conclusions were repeatedly checked and rechecked not only by A. Einstein, but also by other scientists. After a certain time, A. Einstein, in response to A. Friedman's letter, acknowledged the correctness of these decisions and called A. Friedman "the first scientist who took the path of constructing relativistic models of the Universe." Unfortunately, A. Friedman died early. In his person, science has lost a talented scientist.

   As noted above, neither A. Friedman, nor A. Einstein were aware of the data on the fact of "recession" of galaxies obtained by the American astronomer W. Slipher (1875-1969) in 1912. By 1925, he measured the speed of several dozen galaxies. Therefore, A. Friedman's cosmological ideas were discussed primarily in theoretical terms. HOalready v 1929

   G.Americanastronomer E. Hubble (1889-1953) with help telescope instrumented spectrumaanalysisfromwing tato callemyNSeffect

   "Reddisplacement ". The light that comes from the galaxies he has observed

   shifted to the red part of the color spectrum of visible light. It said that

   that the observed galaxies are moving away, "scatter" from the observer.

   The "redshift" effect is a special case of the Doppler effect. The Austrian scientist K. Dopler (1803-1853) discovered it in 1824. When the wave source is removed from the device that records the waves, the wavelength increases and becomes shorter when approaching a stationary wave receiver. In the case of light waves, long wavelengths of light correspond to the red segment of the light spectrum (red to violet), short to the violet segment. The effect of "redshift" was used by E. Hubble to measure the distances to galaxies and the speed of their removal: if the "redshift" from the galaxy A, for example, painNSe v two times, how from galaxies V, then the distance to the galaxy A twice as much as before the galaxy V.

   E. Hubble found that all observed galaxies are moving away in all directions of the celestial sphere at a speed proportional to the distance to them: Vr = Нr, where r - the distance to the observed galaxy, measured in parsecs (1 ps is approximately equal to 3.1 10 1 6 m), Vr - the speed of the observed galaxy, Η - the Hubble constant, or the proportionality coefficient between the speed of a galaxy and the distance to it

   from the observer. The celestial sphere is a concept that is used to describe objects in the starry sky with the naked eye. The ancients considered the celestial sphere to be a reality, on the inner side of which the stars are fixed. Calculating the value of this quantity, which later became known as the Hubble constant, E. Hubble came to the conclusion that it is approximately 500 km / (s Mpc). In other words, a segment of space of one million parsecs increases by 500 km in one second.

   Formula Vr= Нr allows us to consider both the removal of galaxies and the inverse situation, the movement to a certain initial position, the beginning of the "recession" of galaxies in time. The inverse of the Hubble constant has the dimension of time: t(time) = r / Vr = 1/ H. When the value H, which was mentioned above, E. Hubble obtained the time of the beginning of the "recession" of galaxies equal to 3 billion years, which caused him to doubt the relativity of the correctness of the value he calculated. Using the effect of "redshift", E. Hubble reached the most distant galaxies known at that time: the further a galaxy is, the less its brightness is perceived by us. This allowed E. Hubble to say that the formula Vr = Hr expresses the observed fact of the expansion of the Universe, which was mentioned in A. Friedman's model. Astronomical studies of E. Hubble began to be considered by a number of scientists as experimental confirmation of the correctness of A. Friedman's model of a non-stationary, expanding Universe.

   Already in the 30s, some scientists expressed doubts about the data

   E. Hubble. For example, P. Dirac put forward a hypothesis about the natural reddening of light quanta due to their quantum nature, interaction with the electromagnetic fields of outer space. Others pointed to the theoretical inconsistency of the Hubble constant: why should the magnitude of the Hubble constant be the same at every moment of time in the evolution of the Universe? This stable constancy of the Hubble constant suggests that the laws of the Universe known to us, operating in the Megalaxy, are obligatory for the entire Universe as a whole. Perhaps, as critics of the Hubble constant say, there are some other laws that the Hubble constant will not comply with.

   For example, they say, light can "turn red" due to the influence of the interstellar (ISS) and intergalactic (IGZ) media on it, which can lengthen the wavelength of its movement towards the observer. Another issue that caused discussions in connection with the studies of E. Hubble was the question of the assumption of the possibility of galaxies moving at a speed exceeding the speed of light. If this is possible, then these galaxies can disappear from our observation, since from the general theory of relativity no signals can be transmitted faster than light. Nevertheless, most scientists believe that E. Hubble's observations established the fact of the expansion of the Universe.

   The fact of the expansion of galaxies does not mean expansion within the galaxies themselves, since their structural certainty is provided by the action of the internal forces of gravity.

   E. Hubble's observations contributed to the further discussion of A. Friedman's models. BelgianmonkandastronomerJ.Lemetr(vneRhowlhalf of the past)centurydrewattentionanieonsleblowingcircumstance:scattering of galaxiesmeansextensionspace,hence,vpast

   It wasdecreasevolumeandNSlrelationsvesociety. Lemaitre called the initial density of matter a protoatom with a density of 10 9 3 g / cm 3, from which the world was created by God. It follows from this model that the concept of density of matter can be used to determine the limits of applicability of the concepts of space and time. At a density of 10 9 3 g / cm 3 the concepts of time and space lose their usual physical meaning. This model has drawn attention to the physical state with superdense and superhot physical parameters. In addition, models have been proposed pulsatingUniverse: The universe expands and contracts, but never goes to extreme limits. Models of a pulsating Universe attach great importance to measuring the density of energy-matter in the Universe. When the critical density limit is reached, the universe expands or contracts. The result was the term "SingulI amrnoe "(lat. singularus - separate, single) state in which the density and temperature take on an infinite value. This line of research is faced with the problem of the "hidden mass" of the Universe. The point is that the observed mass of the Universe does not coincide with its mass calculated on the basis of theoretical models.

   Model"Bigexplosion ". Our compatriot G. Gamow (1904-1968)

   worked at Petrograd University and was familiar with cosmological ideas

   A. Fridman. In 1934 he was sent on a business trip to the United States, where he remained for the rest of his life. Under the influence of A. Friedman's cosmological ideas, G. Gamow became interested in two problems:

   1) the relative abundance of chemical elements in the Universe and 2) their origin. By the end of the first half of the twentieth century. there was a lively discussion on these issues: where can severe chemical elements if hydrogen (1 1 H) and helium (4 H) are the most abundant chemical elements in the universe. G. Gamow suggested that chemical elements trace their history from the very beginning of the expansion of the Universe.

   ModelG.Gamownacalledmodel"Bigexplosion ",nOsheIt has

   andothertitle:"A-B-D-theory"... This title indicates the initial letters of the authors of the article (Alfer, Bethe, Gamow), which was published in 1948 and contained a model of the "hot Universe", but the main idea of ​​this article belonged to G. Gamow.

   Briefly about the essence of this model:

   1. The "original beginning" of the Universe, according to Friedman's model, was represented by a superdense and superhot state.

   2. This state arose as a result of the previous compression of the entire material, energy component of the Universe.

   3. This state corresponded to an extremely small volume.

   4. Energy-matter, having reached a certain limit of density and temperature in this state, exploded, the Big Bang occurred, which Gamow called

   "Cosmological Big Bang".

   5. It is about an unusual explosion.

   6. The Big Bang gave a certain speed of movement to all fragments of the original physical state before the Big Bang.

   7. Since the initial state was super-hot, the expansion should retain the remnants of this temperature in all directions of the expanding Universe.

   8. The magnitude of this residual temperature should be approximately the same at all points of the Universe.

   This phenomenon was called relict (ancient), background radiation from m.

   1953 G. Gamow calculated the wave temperature of the relict radiation. Him

   it turned out 10 K. The relic radiation is microwave electromagnetic radiation.

   In 1964, American experts A. Penzias and R. Wilson accidentally discovered relic radiation. Having installed the antennas of the new radio telescope, they could not get rid of interference in the 7.8 cm range. These interference, noise came from space, the same in magnitude and in all directions. Measurements of this background radiation gave a temperature of less than 10 K.

   Thus, G. Gamow's hypothesis about relict, background radiation was confirmed. In his works on the temperature of background radiation, G. Gamow used A. Friedman's formula, which expresses the dependence of the change in the radiation density in time. In parabolic ( K> 0) model of the universe. Friedman considered a state when radiation prevails over the matter of an unboundedly expanding Universe.

   According to Gamow's model, there were two epochs in the development of the Universe: a) the predominance of radiation (physical field) over matter;

   b) the predominance of matter over radiation. In the initial period, radiation prevailed over matter, then there was a time when their ratio was equal, and a period when matter began to predominate over radiation. Gamow defined the boundary between these eras - 78 million years.

   At the end of the twentieth century. measuring microscopic changes in background radiation, which is called ripplesbNS, allowed a number of researchers to assert that this ripple represents a change in density substancesandenerGuiv as a result of the action of gravitational forces on early stages of development The universe.

   Model "YingfleggsOnnoyUniverse ".

   The term "inflation" (lat. Inflation) is interpreted as bloating. Two researchers A. Guth and P. Seinhardt proposed this model. In this model, the evolution of the Universe is accompanied by a giant swelling of the quantum vacuum: in 10 -30 s, the size of the Universe increases by 10 50 times. Inflation is an adiabatic process. It is associated with cooling and the emergence of a distinction between weak, electromagnetic and strong interactions. The analogy of the inflation of the Universe can be roughly represented as the sudden crystallization of a supercooled liquid. Initially, the inflationary phase was seen as the "rebirth" of the universe after the Big Bang. Currently, inflationary models use the concept andnflatonneOthfields... This is a hypothetical field (from the word "inflation"), in which, due to random fluctuations, a homogeneous configuration of this field with a size of more than 10 -33 cm was formed. From it, the expansion and heating of the Universe in which we live occurred.

   The description of events in the Universe based on the “Inflationary Universe” model completely coincides with the description based on the Big Bang model, starting from 10 -30 s of expansion. The inflation phase means that the observable universe is only a part of the universe. In the textbook by T. Ya. Dubnischeva "The Concept of Modern Natural Science", the following course of events is proposed according to the model of the "Inflationary Universe":

   1) t - 10 - 4 5 p. By this time, after the beginning of the expansion of the Universe, its radius was approximately 10 -50 cm. This event is unusual from the point of view of modern physics. It is assumed to be preceded by events generated by the quantum effects of the inflaton field. This time is less than the time of the "Planck era" - 10 - 4 3 s. But this does not bother the supporters of this model, who carry out calculations with a time of 10 -50 s;

   2) t - approximately from 10 -43 to 10 -35 s - the era of the "Great Unification" or the unification of all forces of physical interaction;

   3) t - from about 10 - 3 5 to 10 -5 - the fast part of the inflationary phase,

   when the diameter of the universe has increased by a factor of 10 5 0. We are talking about the emergence and formation of an electron-quark medium;

   4) t- approximately from 10 -5 to 10 5 s, quarks are first confined in hadrons, and then nuclei of future atoms are formed, from which matter is subsequently formed.

   It follows from this model that one second after the beginning of the expansion of the Universe, the process of the emergence of matter, its separation from the photons of electromagnetic interaction and the formation of proto-superclusters and protogalaxies takes place. Heating occurs as a result of the appearance of particles and antiparticles interacting with each other. This process is called annihilation (lat. nihil - nothing or becoming nothing). The authors of the model believe that annihilation is asymmetric towards the formation of ordinary particles that make up our Universe. Thus, the main idea of ​​the Inflationary Universe model is to exclude from cosmology the concept

   "Big Bang" as a special, unusual, exceptional state in the evolution of the Universe. However, an equally unusual state appears in this model. This state NSnfigration andnflaton field. The age of the universe in these models is estimated at 10-15 billion years.

   The “inflationary model” and the “Big Bang” model explain the observed inhomogeneity of the Universe (density of matter condensation). In particular, it is believed that when the Universe was inflated, cosmic inhomogeneities-textures arose as embryos of aggregates of matter, which later expanded to galaxies and their clusters. This is evidenced by the recorded in 1992. the deviation of the temperature of the relic radiation from its average value of 2.7 K by about 0.00003 K. Both models speak of a hot expanding Universe, on average homogeneous and isotropic with respect to the relic radiation. In the latter case, we mean the fact of practically the same value of the relic radiation in all parts of the observable Universe in all directions from the observer.

   There are alternatives to the Big Bang and Inflationary

   Universe ": models of" Stationary Universe "," Cold Universe "and

   "Self-Consistent Cosmology".

   Model"StationaryOf the Universe ". This model was developed in 1948. It was based on the principle of "cosmological constancy" of the Universe: not only in the Universe there should not be a single allocated place, but not a single moment should be allocated in time. The authors of this model are G. Bondi, T. Gold and F. Hoyle, the latter is a well-known author of popular books on the problems of cosmology. In one of his works, he wrote:

   "Every cloud, galaxy, every star, every atom had a beginning, but not the entire universe, the universe is more than its parts, although this conclusion may seem unexpected." This model assumes the presence in the Universe of an internal source, a reservoir of energy, which maintains the density of its energy-matter at a "constant level that prevents the compression of the Universe." For example, F. Hoyle argued that if one atom appeared in one bucket of space every 10 million years, then the density of energy, matter and radiation in the Universe as a whole would be constant. This model does not explain how atoms of chemical elements, matter, etc., arose.

   e. The discovery of the relict, background radiation greatly undermined the theoretical foundations of this model.

   Model« ColdThe universeth». The model was proposed in the sixties

   years of the last century by the Soviet astrophysicist J. Zeldovich. Comparison

   theoretical values ​​of density and temperature of radiation according to the model

   The "Big Bang" with the data of radio astronomy allowed Ya. Zel'dovich to put forward a hypothesis according to which the initial physical state of the Universe was a cold proton-electron gas with an admixture of neutrinos: for each proton there is one electron and one neutrino. The discovery of the relict radiation, which confirms the hypothesis of the initial hot state in the evolution of the Universe, led Zeldovich to abandon his own model of the "Cold Universe". However, the idea of ​​calculating the relationship between the number of different types of particles and the abundance of chemical elements in the Universe turned out to be fruitful. In particular, it was found that the density of energy-matter in the Universe coincides with the density of the relic radiation.

   Model"Universevatom ". This model claims that there is actually not one, but many universes. The model "Universe in an atom" is based on the concept of a closed world according to A. Friedman. A closed world is an area of ​​the Universe in which the forces of attraction between its components are equal to the energy of their total mass. In this case, the outer dimensions of such a universe can be microscopic. From the point of view of an external observer, it will be a microscopic object, but from the point of view of an observer inside this Universe, everything looks different: their galaxies, stars, etc. These objects are called freadmons. Academician A.A. Markov hypothesized that there can be an unlimited number of Fridmons and they can be completely open, that is, they have an entrance to their world and an exit (connection) with other worlds. It turns out a set of Universes, or, as Corresponding Member of the USSR Academy of Sciences I.S.Shklovsky called in one of his works, - Metaverse.

   The idea of ​​a plurality of Universes was expressed by A. Guth, one of the authors of the inflationary model of the Universe. In a swelling Universe, the formation of "aneurysms" (a term from medicine, means protrusion of the walls of blood vessels) from the mother Universe is possible. According to this author, the creation of the universe is quite possible. To do this, you need to compress 10 kg of substance

   to a size less than one quadrillion part of an elementary particle.

   QUESTIONS FOR SELF-TEST

   1. The Big Bang model.

   2. Astronomical research by E. Hubble and their role in development

   modern cosmology.

   3. Relic, background radiation.

   4. Model "Inflationary Universe".