How the universe formed. A Brief History of the Concept of the Universe

It seemed unlikely that the echo of the events that took place in the first milliseconds of the birth of the Universe could reach us. However, this turned out to be possible.

Cosmology, the structure of the Universe, the past, present and future of our world - these questions have always occupied the best minds of mankind. For the development of cosmology, and science as a whole, it is extremely important to understand the Universe as a whole. A special role is played by experimental verification of abstract constructions, their confirmation by observational data, comprehension and comparison of research results, adequate assessment of certain theories. We are now in the middle of the path that leads from solving Einstein's equations to knowing the mystery of the birth and life of the Universe.

The next step on this path was taken by the creator of the theory of chaotic inflation, a graduate of Moscow State University, now a professor at Stanford University, Andrei Dmitrievich Linde, who made a significant contribution to understanding the earliest stage of the development of the Universe. For many years he worked in one of the leading academic Russian institutes - the Physics Institute named after Lebedev of the Academy of Sciences (FIAN), studied the consequences of modern theories of elementary particles, working together with Professor David Abramovich Kirzhnits.

In 1972 Kirzhnits and Linde came to the conclusion that peculiar phase transitions took place in the early Universe, when the differences between different types of interactions suddenly disappeared: strong and electroweak interactions merged into one single force. (A unified theory of weak and electromagnetic interactions carried out by quarks and leptons through the exchange of massless photons (electromagnetic interaction) and heavy intermediate vector bosons (weak interaction) was developed in the late 1960s by Steven Weinberg, Sheldon Glashow, and Abdus Salam.) Linde focused on the study of processes at even earlier stages of the development of the Universe, in the first 10 –30 s after its birth. Earlier it seemed unlikely that the echo of events that took place in the first milliseconds of the birth of the Universe could reach us. However, in recent years, modern methods of astronomical observations have made it possible to look into the distant past.

Cosmology problems

In considering the Big Bang theory, researchers faced problems that were previously perceived as metaphysical. However, questions invariably arose and demanded answers.

What happened when there was nothing? If the Universe was born from a singularity, then it once did not exist. In "Theoretical Physics" by Landau and Lifshitz it is said that the solution of Einstein's equations cannot be continued in the region of negative time, and therefore, within the framework of the general theory of relativity, the question "What was before the birth of the Universe?" doesn't make sense. However, this question continues to worry all of us.

Do parallel lines intersect? At school we were told no. However, when it comes to cosmology, the answer is not so straightforward. For example, in a closed universe like the surface of a sphere, lines that were parallel at the equator intersect at the north and south poles. So is Euclid right? Why does the universe seem flat? Was she like this from the start? To answer these questions, it is necessary to establish what the universe was like at the earliest stage of development.

Why is the universe homogeneous? Actually this is not true. There are galaxies, stars and other irregularities. If you look at that part of the Universe, which is within sight of modern telescopes, and analyze the average distribution density of matter on a cosmic scale, it turns out that it is the same in all directions with an accuracy of 10 -5. Why is the universe homogeneous? Why do the same laws of physics operate in different parts of the Universe? Why is the universe so big? Where did the energy needed for its emergence come from?

Doubts have always arisen, and the more scientists learned about the structure and history of the existence of our world, the more questions remained unanswered. However, people tried not to think about them, perceiving a large homogeneous Universe and non-intersecting parallel lines as a given, not subject to discussion. The last straw that forced physicists to reconsider their attitude to the theory of the early Universe was the problem of relic monopoles.

The existence of magnetic monopoles was proposed in 1931 by the English theoretical physicist Paul Dirac. If such particles really exist, then their magnetic charge must be a multiple of some given value, which, in turn, is determined by the fundamental value of the electric charge. For almost half a century, this topic was practically forgotten, but in 1975 a sensational statement was made that a magnetic monopole was discovered in cosmic rays. The information was not confirmed, but the message reawakened interest in the problem and contributed to the development of a new concept.

According to a new class of theories of elementary particles that arose in the 70s, monopoles could have appeared in the early Universe as a result of phase transitions predicted by Kirzhnits and Linde. Each monopole has a million billion times the mass of a proton. In 1978-1979. Zeldovich, Khlopov and Preskill found that quite a lot of such monopoles were born, so now there would be a monopole for each proton, which means that the Universe would be very heavy and had to quickly collapse under its own weight. The fact that we still exist disproves such a possibility.

Revision of the theory of the early universe

The answer to most of the above questions was obtained only after the emergence of the inflationary theory.

Inflationary theory has a long history. The first theory of this type was proposed in 1979 by RAS Corresponding Member Alexei Alexandrovich Starobinsky. His theory was quite complex. Unlike subsequent works, she did not try to explain why the Universe is large, flat, homogeneous, isotropic. However, it had many important features of inflationary cosmology.

In 1980, an employee of the Massachusetts Institute of Technology Alan Goose ( Alan guth) in the article "The Swelling Universe: A Possible Solution to the Horizon and Flatness Problem" he outlined an interesting scenario of the swelling Universe. Its main difference from the traditional theory of the Big Bang was the description of the birth of the universe in the period from 10 -35 to 10 -32 s. Gus suggested that at this time the universe was in a state of the so-called "false" vacuum, in which its energy density was extremely high. Therefore, the expansion proceeded faster than according to the Big Bang theory. This stage of exponentially fast expansion was called inflation (inflation) of the Universe. Then the false vacuum disintegrated, and its energy passed into the energy of ordinary matter.

Gus's theory was based on the theory of phase transitions in the early Universe developed by Kirzhnits and Linde. Unlike Starobinsky, Gus set himself the goal of using one simple principle to explain why the Universe is large, flat, homogeneous, isotropic, and also why there are no monopoles. The stage of inflation could solve these problems.

Unfortunately, after the collapse of the false vacuum in the Goos model, the universe turned out to be either very inhomogeneous or empty. The fact is that the decay of the false vacuum, like the boiling of water in a kettle, occurred due to the formation of bubbles of a new phase. In order for the energy released in this case to pass into the thermal energy of the Universe, it was necessary to collide the walls of huge bubbles, and this should lead to a violation of the homogeneity and isotropy of the Universe after inflation, which contradicts the set task.

Although Goos' model did not work, it stimulated the development of new scenarios for an inflating universe.

New inflationary theory

In mid-1981, Linde proposed the first version of a new scenario of an inflating universe, based on a more detailed analysis of phase transitions in the Grand Unification model. He came to the conclusion that in some theories the exponential expansion does not end immediately after the formation of bubbles, so that inflation can go not only before the phase transition with the formation of bubbles, but also after, already inside them. In this scenario, the observable part of the Universe is considered to be contained within a single bubble.

In the new scenario, Linde showed that heating after inflation occurs due to the creation of particles during oscillations of the scalar field (see below). Thus, the collisions of the walls of the bubbles, generating inhomogeneities, became unnecessary, and thus the problem of large-scale homogeneity and isotropy of the Universe was solved.

The new scenario contained two key points: first, the properties of the physical state inside the bubbles must change slowly to ensure inflation inside the bubble; secondly, at later stages, there should be processes that ensure the heating of the Universe after the phase transition. A year later, the researcher revised his approach, proposed in the new inflationary theory, and came to the conclusion that phase transitions are not needed at all, as well as hypothermia and the false vacuum with which Alan Goose started. It was an emotional shock, since it was necessary to abandon the ideas that were considered true about the hot Universe, phase transitions and hypothermia. It was necessary to find a new way to solve the problem. Then the theory of chaotic inflation was put forward.

Chaotic inflation

The idea behind Linde's theory of chaotic inflation is very simple, but in order to explain it, you need to introduce the concept of a scalar field. There are directed fields - electromagnetic, electric, magnetic, gravitational, but there can be at least one more - scalar, which is not directed anywhere, but is simply a function of coordinates.

The closest (although not accurate) analogue of a scalar field is the electrostatic potential. The voltage in the US electrical networks is 110 V, and in Russia - 220 V. If a person were to hold on to the American wire with one hand and the Russian one with the other, the potential difference would kill him. If the voltage was the same everywhere, there would be no potential difference and the current would not flow. So in a constant scalar field there is no potential difference. Therefore, we cannot see a constant scalar field: it looks like a vacuum, which in some cases can have a high energy density.

It is believed that without fields of this type it is very difficult to create a realistic theory of elementary particles. In recent years, almost all particles predicted by the theory of electroweak interactions, except for the scalar one, have been discovered. The search for such particles is one of the main goals of the huge accelerator currently under construction at CERN, Switzerland.

The scalar field was present in almost all inflationary scenarios. Gus suggested exploiting the potential with several deep lows. Linde's new inflationary theory needed a potential with an almost flat top, but later, in a chaotic inflation scenario, it turned out that it was enough to take an ordinary parabola and everything worked.

Consider the simplest scalar field, the potential energy density of which is proportional to the square of its magnitude, just as the energy of a pendulum is proportional to the square of its deviation from the equilibrium position:

A small field will know nothing about the Universe and will oscillate near its minimum. However, if the field is large enough, then it will roll down very slowly, accelerating the Universe at the expense of its energy. In turn, the speed of the Universe (and not any particles) will slow down the fall of the scalar field.

Thus, a large scalar field leads to a high expansion rate of the Universe. The high expansion rate of the Universe prevents the field from decreasing and thereby prevents the potential energy density from decreasing. And the high energy density continues to accelerate the Universe at an ever greater speed. It is this self-sustaining regime that leads to inflation, an exponentially rapid inflation of the Universe.

To explain this amazing effect, it is necessary to jointly solve the Einstein equation for the scale factor of the Universe:

and the equation of motion for a scalar field:

Here H is the so-called Hubble constant, proportional to the energy density of the scalar field of mass m (this constant actually depends on time); G is the gravitational constant.

Researchers have already considered how the scalar field will behave in the vicinity of a black hole and during the collapse of the universe. But somehow the exponential expansion mode was not found. And it was only necessary to write the complete equation for the scalar field, which in the standard version (that is, without taking into account the expansion of the Universe) looked like the equation for a pendulum:

But some additional term intervened - the friction force, which was associated with geometry; no one took it into account at first. It is the product of the Hubble constant and the speed of the field:

When the Hubble constant was large, the friction was also great, and the scalar field decreased very slowly. Therefore, the Hubble constant, which is a function of the scalar field, remained almost unchanged for a long time. The solution to the Einstein equation with a slowly varying Hubble constant describes an exponentially rapidly expanding universe.

This stage of the exponentially fast expansion of the Universe is called inflation.

How does this regime differ from the usual expansion of the Universe filled with ordinary matter? Let's assume that the Universe filled with dust has expanded 2 times. Then its volume increased 8 times. This means that in 1 cm 3 there is 8 times less dust. If we solve the Einstein equation for such a Universe, it turns out that after the Big Bang, the density of matter dropped rapidly, and the rate of expansion of the Universe was rapidly decreasing.

The same would be the case with a scalar field. But while the field remained very large, it supported itself, like Baron Munchausen pulling himself out of the swamp by the pigtail. This was possible due to the friction force, which was significant at high field values. In accordance with the theories of the new type, the universe was expanding rapidly, and the field remained almost unchanged; accordingly, the energy density did not change either. Hence, the expansion proceeded exponentially.

Gradually, the field decreased, the Hubble constant also decreased, the friction became small, and the field began to oscillate, generating elementary particles. These particles collided, exchanged energy and gradually came to a state of thermodynamic equilibrium. As a result, the universe became hot.

It used to be thought that the universe was hot from the start. This conclusion was reached by studying microwave radiation, which was interpreted as a consequence of the Big Bang and subsequent cooling. Then they began to think that at first the Universe was hot, then inflation occurred, and after it the Universe became hot again. However, in the theory of chaotic inflation, the first hot stage turned out to be unnecessary. But why do we need the stage of inflation, if at the end of this stage the universe still became hot, as in the old theory of the Big Bang?

Exponential expansion

There are three simplest models of the universe: flat, open, and closed. A flat universe is like the surface of a flat table; parallel lines in such a universe always remain parallel. The open universe is like the surface of a hyperboloid, and the closed universe is like the surface of a ball. Parallel lines in such a universe intersect at its north and south poles.

Let's assume that we live in a closed universe, which at first was as small as a ball. According to the Big Bang theory, it grew to a decent size, but still remained relatively small. And according to the inflationary theory, a tiny ball has become huge as a result of an exponential explosion in a very short time. While on it, the observer would see a flat surface.

Imagine the Himalayas, where there are many different ledges, crevices, abysses, hollows, boulders, that is, inhomogeneities. But suddenly someone or something in a completely incredible way increased the mountains to gigantic proportions, or we shrank, like Alice in Wonderland. Then, being on the top of Everest, we will see that it is completely flat - it was as if stretched, and the heterogeneities ceased to have any meaning. The mountains remain, but in order to climb at least one meter, you need to go incredibly far. Thus, the homogeneity problem can be solved. This also explains why the universe is flat, why parallel lines do not intersect, and why monopoles do not exist. Parallel lines can intersect and monopoles can exist, but only so far away from us that we cannot see it.

The emergence of galaxies

The small universe became colossal and everything became homogeneous. But what about galaxies? It turned out that in the course of the exponential expansion of the Universe, small quantum fluctuations, which always exist, even in empty space, due to the quantum mechanical principle of uncertainty, stretched to colossal sizes and turned into galaxies. According to inflationary theory, galaxies are the result of amplified quantum fluctuations, i.e. amplified and frozen quantum noise.

For the first time, this striking possibility was pointed out by FIAN employees Vyacheslav Fedorovich Mukhanov and Gennady Vasilievich Chibisov in a work based on the model proposed in 1979 by Starobinsky. Shortly thereafter, a similar mechanism was discovered in the new inflationary scenario and in the theory of chaotic inflation.

Speckled sky

Quantum fluctuations led not only to the birth of galaxies, but also to the anisotropy of the relict radiation with a temperature of about 2.7 K, coming to us from the distant regions of the Universe.

Modern artificial satellites of the Earth help scientists to study the relic radiation. The most valuable data was obtained using the WMAP space probe ( Wilkinson Microwave Anisotropy Probe), named after astrophysicist David Wilkinson ( David Wilkinson). Its hardware resolution is 30 times greater than that of its predecessor, the COBE spacecraft.

Previously it was believed that the temperature of the sky is everywhere equal to 2.7 K, but WMAP was able to measure it with an accuracy of 10 -5 K with high angular resolution. According to the data obtained in the first 3 years of observations, the sky turned out to be heterogeneous: somewhere hot, and somewhere colder. The simplest models of inflationary theory predicted ripples in the sky. But until the telescopes recorded its spotting, only three-degree radiation was observed, which served as a powerful confirmation of the theory of a hot universe. Now it turned out that the theory of a hot universe is not enough.

We managed to obtain photographs of inflated quantum fluctuations that appeared 10-30 s after the birth of the universe and have survived to this day. The researchers not only found the patchiness of the sky, but also studied the spectrum of the spots, that is, the signal intensity in different angular directions.

The results of high-precision measurements of radiation polarization carried out with the help of WMAP confirmed the theory of the expansion of the Universe and made it possible to establish when the ionization of intergalactic gas, caused by the very first stars, took place. The information received from the satellite confirmed the position of the inflationary theory that we live in a large flat Universe.

In the figure, the red line shows the prediction of the inflationary theory, and the black dots correspond to the experimental data of WMAP. If the universe were not flat, the peak of the graph would be to the right or to the left.

Eternal and endless

Let's look again at the figure showing the simplest potential of a scalar field (see above). In the region where the scalar field is small, it oscillates, and the Universe does not expand exponentially. In the region where the field is large enough, it slowly decreases, and small fluctuations appear on it. At this time, there is an exponential expansion and inflation. If the scalar field were even larger (marked in blue on the graph), then due to tremendous friction it would hardly decrease, quantum fluctuations would be huge, and the Universe could become fractal.

Imagine that the Universe is expanding rapidly, and in some place the scalar field, instead of rolling to a minimum of energy, jumps up due to quantum fluctuations (see above). At the point where the field jumped, the universe is expanding exponentially faster. A low-lying field is unlikely to bounce, but the higher it is, the more likely such a development of events is, and hence the exponentially larger volume of the new area. In each of these even areas, the field can also jump upward, which leads to the creation of new exponentially growing parts of the Universe. As a result, instead of looking like one huge growing ball, our world becomes like an ever-growing tree, consisting of many such balls.

Inflationary theory provides us with the only currently known explanation for the homogeneity of the observable part of the Universe. Paradoxically, the same theory predicts that on an extremely large scale, our Universe is absolutely inhomogeneous and looks like a huge fractal.

The figure shows schematically how one swelling region of the Universe generates more and more new parts of it. In this sense, it becomes eternal and self-healing.

The properties of space-time and the laws of interaction of elementary particles with each other in different regions of the Universe can be different, as well as the dimensions of space and the types of vacuum.

This fact deserves a more detailed explanation. According to the simplest theory with one potential energy minimum, the scalar field rolls down to this minimum. However, more realistic versions allow many minima with different physics, which resembles water, which can be in different states: liquid, gaseous and solid. Different parts of the Universe can also be in different phase states; this is possible in inflationary theory even without taking into account quantum fluctuations.

The next step, based on the study of quantum fluctuations, is the theory of a self-healing universe. This theory takes into account the process of constant reconstruction of swelling regions and quantum jumps from one vacuum state to another, enumerating different possibilities and dimensions.

So the Universe becomes eternal, endless and diverse. The entire universe will never collapse. However, this does not mean that there are no singularities. On the contrary, a significant part of the physical volume of the Universe is always in a state close to a singular one. But since different volumes pass it at different times, there is no single end of space-time, after which all regions disappear. And then the question of the multiplicity of worlds in time and space takes on a completely different sound: the Universe can reproduce itself indefinitely in all its possible states.

This statement, which was based on Linde's work in 1986, took on a new dimension a few years ago when string theorists (a leading candidate for the theory of all fundamental interactions) concluded that 10 100 –10 1000 various vacuum states. These states differ due to the extraordinary diversity of the possible structure of the world at ultra-short distances.

Taken together with the theory of a self-healing inflationary universe, this means that during inflation, the universe breaks up into infinitely many parts with an incredibly large number of different properties. Cosmologists call this scenario the theory of the eternal inflationary multiverse ( multiverse), and string theorists call it the string landscape.

Inflationary cosmology 25 years ago looked like something intermediate between physical theory and science fiction. Since then, many of the predictions of this theory have been tested, and it has gradually acquired the features of the standard cosmological paradigm. But it's too early to calm down. This theory continues to develop and change rapidly even now. The main problem is the development of models of inflationary cosmology based on realistic versions of the theory of elementary particles and string theory. This question can be the topic of a separate report.

Today I want to tell you about the history of our universe. About how the universe has turned from a small point into what we are now observing around us.

Here we go.

The universe has been around for nearly 14 billion years. During this very long period of time, it has overcome several eras of its history. Now there is the 13th stage of the development of the Universe, which is called the "era of matter".

What are the names of all phases of the evolution of the Universe, how long did they last, what happened during them? How did the world around us develop?

This article will answer you these questions.

I will describe all the stages of the history of the universe in order from the earliest to the present. Therefore, let's start with the "Augustinian era".

Augustine era.

This era includes the state of the universe "before" and at the moment of the Big Bang. Nothing is really known about this stage of the development of the world - there are only hypotheses - since modern physical theories cannot describe events before the "Planck era". Scientists know only that at the very end of this era the Big Bang occurred - suddenly the expansion of space began. By the beginning of this truly grandiose event, the Universe was imprisoned in a very small point, possessing infinite density and temperature, i.e. was in a state of "cosmological singularity".

Planck era.

This is the earliest stage in the development of the Universe, about which there are any theoretical assumptions and descriptions. This phase began immediately after the Big Bang and lasted for the so-called. "Planck time" from 0 to 10 -43 seconds after the birth of the universe.

At that time (God knows what was happening) the size of the universe was very small. So much so that quantum effects - phenomena that happen to particles - prevailed over physical interactions.

The universe in this epoch also had a Planck temperature (10 32 Kelvin), energy (10 19 billion electron volts), radius (10 -35 meters, which is equal to the Planck length) and density (10 97 kg / m 3).

All four types of interaction of particles and bodies consisting of them (they are also called "fundamental") - strong nuclear and weak nuclear, electromagnetic, gravitational - were then indistinguishable from each other and united. But this did not last long. Everything was interfered with by the very high temperature and density of matter.

The era of great unification.

This phase of the development of the Universe began from 10 -43 seconds and ended 10 -35 seconds after the Big Bang. At the very beginning, a phase transition of matter took place (similar to the condensation of a liquid from a gas, but in relation to elementary particles). This happened due to the separation of gravity from the "one fundamental interaction".

The era of the Great Unification ended with another division. The universe has cooled down to 10 28 Kelvin and the strong interaction has become independent. Now only the electromagnetic and weak nuclear forces represented a single whole.

Such an event entailed a new phase transition. Thanks to him, in the next era in the history of the Universe, new particles appeared, and space-time began a large-scale and sharp expansion. There are serious changes in the density of the distribution of matter.

Inflationary stage.

The inflation phase is located on a timeline between 10 -35 and 10 -32 seconds after the Big Bang. During that era, the Universe increased its size many times over. Previously, the radius of the whole world was equal to the "Planck length", but now space has expanded to the size of a whole orange. And then it continued to grow with acceleration.

Several types of particles were formed. These were quarks (fundamental particles that make up hadrons - for example, protons and neutrons), electrons, hyperons and neutrinos (neutral fundamental particles from the class of leptons).

After some time, the temperature of the Universe dropped, due to which another phase transition took place. Because of this, the so-called. "violation of CP-invariance" and the first processes of such a phenomenon as "baryogenesis" began.

Baryogenesis- this is the union of quarks and gluons into new, compound particles - hadrons.

In addition, a mysterious "baryon asymmetry of the Universe" arose - the predominance of matter over anti-matter. Scientists have still not been able to explain the reasons for its occurrence.

In addition to the above, physicists and cosmologists have assumptions that in this era the Universe has gone through several cycles of repeated heating and cooling.

By the end of the inflationary era, the building material of the universe was a plasma of quarks, anti-quarks and gluons (carriers of strong interactions).

A further decrease in the temperature of the Universe led to the next phase transition. It consists in the formation of physical forces, fundamental interactions and elementary particles in their modern form.

This phase transition fit as much as three epochs and ended with "primary nucleosynthesis".

Electroweak era.

Between 10 -32 and 10 -12 seconds after the birth of the universe. So far, the electromagnetic and weak interactions have represented a single electroweak, since the temperature of the universe is still very high. then the Higgs bosons appeared (the same ones that were found 3 years ago at the Large Hadron Collider), W - and Z - basons.

In addition to new exotic particles and quark-gluon plasma, space was filled with photons (fundamental particles, or quanta, of electromagnetic radiation) and leptons.

The era of quarks.

This phase is located in the period from 10 -12 to 10 -6 seconds after the Big Bang. Then there was a violation of "electroweak symmetry". Now all fundamental interactions exist separately from each other.

In the quark era, temperature and energy are still too high for quarks to finally merge into hadrons.

A significant transformation will take place only at the next stage of the development of the world.

Age of Hadrons.

Between 10 -6 and 100 seconds after the birth of the universe. Finally, the quark-gluon plasma has cooled to such an extent that baryogenesis was completed and hadrons and anti-hadrons were born. However, most of these particles have annihilated (mutually annihilated). Only a small remnant of them has survived.

Soon the Universe cooled and expanded so much that its temperature was only enough to create leptons and antileptons. These particles are rapidly becoming the dominant mass in the universe.

The era of the Leptons.

In the period from 100 seconds to 3 minutes after the Big Bang, the epoch of leptons is located. Then the Universe became transparent to neutrinos.

The space continues to cool. At the end of the epoch, the temperature dropped to a point at which the formation of new leptons became impossible. And the pair "lepton-antilepton" overtakes the fate of hadrons. Most of them cancel each other out. A very small number of leptons remained in the universe, due to which the dominance of photons began.

The era of Nucleosynthesis.

Simultaneously with the epoch of leptons, this stage of the history of the Universe was going on. Due to the sufficient cooling of matter, the surviving hadrons combined into atomic nuclei heavier than hydrogen. This process is called "primary nucleosynthesis".

During this phase, the primary composition of stellar matter arose: 75% hydrogen, almost 25% helium, some lithium, deuterium and boron.

Proton Era.

It started 3 minutes after the Big Bang and ended 380,000 years later. The substance began to dominate the radiation.

At the end of the epoch, hydrogen recombination (a process opposite to ionization) took place. Due to the further decrease in temperature and the expansion of the universe, gravity has become the dominant force.

379,000 years after the Big Bang, at a temperature of the Universe of 3000 Kelvin, a significant event took place - the nuclei of atoms and electrons combined into the first atoms. The "primary recombination" began. It was a turning point: matter passed from a plasma opaque to electromagnetic radiation into a gaseous state. The universe has finally become transparent.

In the past 379,000 years, photons have suffered as best they can. Various charged elementary particles, which used to be a carriage and a small cart, obstructed the light. The quanta of light interacted with them, which is why they experienced constant "kicks" and "jolts" from the side of their "brothers". The photons were always deflected or absorbed by charged particles. As a result, the light was very scattered. If the observer got into this era, he would see in front of him only a thick fog.

As you know, photons interact only with positively and negatively charged particles. And at the end of the "proton era" of a quantum of light, luck finally turned around. Negative electrons and positive protons are grouped together with neutrons into neutrally charged atoms. Thanks to the new compound particles, photons were able to move freely in space and hardly interact with matter.

The relic radiation is the very photons emitted by the plasma towards the future location of the Earth and, due to recombination, avoided scattering. They still reach us, overcoming the expanding space.

Dark Ages.

Came immediately after the "proton era" and lasted 550 million years. The universe was so cold that after the proton era, when it shimmered with red hues, space was plunged into blackness.

It was a boring era of complete darkness. There were no sources of light (stars or galaxies). Planets and asteroids even more so. Space was filled predominantly with hydrogen, helium and microwave background radiation.

Reionization.

Part of the history of the universe that began immediately after the Dark Ages and lasted 250 million years. Compared to the past, this era was more fun and colorful.

Clusters began to form - isolated accumulations of dust of interstellar gas, which appeared due to the forces of gravity. The first dense objects were quasars. Then the first stars flared up, and gas and dust nebulae appeared.

Under the force of gravity, they united into star clusters, those into galaxies. The latter have formed their own clusters and superclusters.

Then, in the depths of the stars, heavy elements were formed in large quantities. Supernova explosions carried them across the Universe, from which cold planets, asteroids, meteoric bodies, and, ultimately, living organisms were formed.

The era of substance.

Starting 800 million years after the Big Bang. This Epoch is still going on.

Several billion years after "reionization", the formation of planets and planetary systems, including the Solar System, began. A little over 8.4 billion years after the Big Bang, the Earth formed, and another 500 million years later, life appeared on it.

Cosmologists continue to move towards the ultimate comprehension of the processes that created and shaped the Universe.

The universe is so large in space and time that for almost the entire history of mankind it remained inaccessible both to our instruments and to our minds. But everything changed in the 20th century, when new ideas appeared - from Einstein's general theory of relativity to modern theories of elementary particles. Success was also achieved thanks to powerful instruments - from the 100- and 200-inch reflectors created by George Ellery Hale and who discovered galaxies beyond the Milky Way for us, to the Hubble Space Telescope, which took us to the era of the birth of galaxies. Progress has accelerated over the past 20 years. It became clear that dark matter does not consist of ordinary atoms, that there is dark energy. Bold ideas about cosmic inflation and plurality of universes were born.

A hundred years ago, the Universe was simpler: eternal and unchanging, consisting of one galaxy containing several million visible stars. The modern picture is much more complex and much richer. Space originated 13.7 billion years ago as a result of the Big Bang. A fraction of a second after the beginning, the universe was a hot, shapeless mixture of elementary particles - quarks and leptons. As it expanded and cooled, structures arose step by step: neutrons and protons, atomic nuclei, atoms, stars, galaxies, galaxy clusters and, finally, superclusters. The observable part of the Universe now contains 100 billion galaxies, each of them contains about 100 billion stars and, probably, the same number of planets. The galaxies themselves are kept from expanding by the gravity of mysterious dark matter. And the Universe continues to expand and even does it with acceleration under the influence of dark energy - an even more mysterious form of energy, whose gravitational force does not attract, but repels.

The main theme of our story about the universe is the evolution from a primitive quark "soup" to the increasing complexity of galaxies, stars, planets and life observed today. These structures have appeared one after another over billions of years, obeying the basic laws of physics. Traveling into the past, to the era of inception, cosmologists first move through the detailed history of the Universe back, to the first microsecond, then to $ 10 ^ (- 34) $ from the beginning (there are clear ideas about this time, but there is no clear confirmation of them yet) and finally, by the very moment of birth (about which there are only guesses so far). Although we are not yet able to fully understand how the universe was born, we already have amazing hypotheses, such as the concept of a multiple universe, which includes an infinite number of unconnected subuniverses.

BASIC PROVISIONS

• Our universe began with a hot Big Bang 13.7 billion years ago and has been expanding and cooling ever since. It has evolved from a formless mixture of elementary particles to a modern highly structured space.
• The first microsecond was the defining period when matter began to dominate over antimatter, the structure of future galaxies and their clusters was born, and dark matter arose - an unknown substance that holds this structure.
• The future of the universe is determined by dark energy, an unknown form of energy that is responsible for the acceleration of cosmological expansion that began several billion years ago.

Expanding Universe

In 1924, using the 100-inch Hooker telescope of the Mount Wilson Observatory, Edwin Hubble discovered that fuzzy nebulae, which remained mysterious for several centuries, are the same galaxies as ours. Thus, Hubble increased our understanding of the Universe by a factor of 100 billion! A few years later, he proved that galaxies move away from each other, obeying a mathematical pattern, now known as Hubble's law: the further a galaxy is, the faster it moves. It is from this law that the Big Bang was 13.7 billion years ago.

SPACE EXPANSION
The evolution of the Universe occurs as a result of the expansion of space. As space expands like the envelope of a balloon, galaxies move away from each other, and light waves lengthen (redden).

Within the framework of general relativity, Hubble's law is interpreted as follows: space itself expands, and galaxies move with it (Fig. Above). Light also stretches, experiencing a redshift, which means it loses energy, so the Universe cools down as it expands. Cosmic expansion helps to understand how the modern universe was formed. If you mentally rush into the past, then the Universe will become denser, hotter, more unusual and simpler. Approaching the very beginning, we come into contact with the deepest mechanisms of nature, using an accelerator more powerful than any built on Earth - the Big Bang itself.

Peering through a telescope into space, astronomers literally fall into the past - and the larger the telescope, the deeper their gaze penetrates. The light coming from distant galaxies shows us ancient epochs, and its redshift shows how much the Universe has expanded over the past time. The currently observed record redshift of about eight, which means that this light was emitted when the size of the universe was nine times smaller than it is today, and the age is only a few hundred million years. Instruments such as the Hubble Space Telescope and the ten-meter Keck telescopes on Mauna Kea easily transport us into the formation of galaxies like ours - several billion years after the Big Bang. Light from earlier eras is so strongly redshifted that astronomers are forced to receive it in the infrared and radio bands. Telescopes under construction, such as the 6.5-meter James Webb Infrared Space Telescope and the Atacama Large Millimeter Array (ALMA), a network of 64 radio telescopes in northern Chile, will take us back in time to the birth of the earliest stars and galaxies.

Computer simulations show that these stars and galaxies appeared when the universe was about 100 million years old. Before that, the universe went through a period called the dark era, when it was pitch black. Space was filled with a shapeless mass of five parts of dark matter and one part of hydrogen with helium, which was rarefied as the Universe expanded. The matter was slightly inhomogeneous in density, and gravity acted as an amplifier of these inhomogeneities: denser regions expanded more slowly than less dense ones. By the time of 100 Ma, the densest regions not only slowed down their expansion, but even began to contract. Each of these zones contained about 1 million solar masses of matter; they became the first gravitationally bound objects in space.

The bulk of their mass was made up of dark matter, which, according to its name, is not capable of emitting or absorbing light. Therefore, it formed very extended clouds. On the other hand, hydrogen and helium, emitting light, lost energy and collapsed towards the center of each cloud. In the end, they shrank so much that they turned into stars. These first objects were much more massive than modern ones - hundreds of solar masses. Having lived a very short life, they exploded, throwing out the first heavy elements into space. A few billion years later, these clouds with masses of millions of solar masses were grouped into the first galaxies under the influence of gravity.

Radiation from the very first hydrogen clouds, which experienced a strong redshift due to expansion, could be detected using huge complexes of radio antennas with a total receiving area of ​​about a square kilometer. When these radio telescopes are created, it will become known how the first generation of stars and galaxies ionized hydrogen and thereby ended the dark era. (see: A. Loeb Dark Ages of the Universe // VMN, No. 3, 2007).

A faint glow of a hot start

Behind the dark era, the glow of the hot Big Bang at a redshift of 1100 is noticeable. This initially visible (red-orange) radiation, due to the redshift, became not even infrared, but microwave. Looking back into that era, we see only a wall of microwave radiation filling the entire sky — the cosmic microwave background radiation discovered in 1964 by Arno Penzias and Robert Wilson. This is a faint reflection of the Universe, which was in its infancy 380 thousand years, in the era of the formation of atoms. Before that, it was an almost homogeneous mixture of atomic nuclei, electrons and photons. When the Universe cooled down to a temperature of about 3000 K, nuclei and electrons began to combine into atoms. The photons stopped scattering on electrons and began to move freely through space, demonstrating what the Universe was like long before the birth of stars and galaxies.

In 1992, NASA's Cosmic Background Explorer (COBE) satellite found that the intensity of this radiation changed slightly - by about 0.001%, indicating a slight inhomogeneity in the distribution of matter. The degree of primary inhomogeneity turned out to be sufficient for small compaction to become a "seed" for future galaxies and their clusters, which later grew under the influence of gravity. The distribution of background radiation inhomogeneities across the sky indicates important properties of the Universe: its average density and composition, and the earliest stages of its evolution. A careful study of these inhomogeneities has told us a lot about the universe.

COSMIC MICROWAVE BACKGROUND RADIATION is an image of the Universe in its infancy of 380 thousand years. Weak variations in the intensity of this radiation (marked in color) serve as the cosmic Rosetta stone, which provides a clue to the mysteries of the universe - its age, density, composition and geometry..

THE HUBBLE SUPER-DEEP FIELD, the most sensitive space image ever captured, capturing more than 1,000 galaxies in their early stages of formation.

Moving from this point back to the beginning of the evolution of the Universe, we will see how the primary plasma becomes hotter and denser. Until the age of about 100 thousand years, the radiation energy density was higher than that of matter, which kept the matter from fragmentation. And at that moment, the gravitational clustering of all structures observed in the Universe now began. Even closer to the beginning, when the age of the Universe was less than one second, there were no atomic nuclei, but only their components - protons and neutrons. The nuclei arose when the universe was a few seconds old, and the temperature and density became suitable for nuclear reactions. In this nucleosynthesis of the Big Bang, only light chemical elements were born: a lot of helium (about 25% by mass of all atoms in the Universe) and a little lithium, deuterium and helium-3. The rest of the plasma (about 75%) remained in the form of protons, which eventually became hydrogen atoms. All other elements of the Periodic Table were born billions of years later in the bowels of stars and during their explosions.

THE UNIVERSE CONSISTS primarily of dark energy and dark matter; the nature of both is unknown. The common matter from which stars, planets and interstellar gas are formed is only a small fraction.

Nucleosynthesis theory accurately predicts the abundances of elements and isotopes measured in the most ancient objects in the universe - in the oldest stars and gas clouds with a large redshift. The deuterium content, which is very sensitive to the average density of atoms in the Universe, plays a special role: its measured value shows that ordinary matter is (4.5 ± 0.1)% of the total energy density. The rest is dark matter and dark energy. This is in exact agreement with the compositional data obtained from the analysis of the background radiation. This alignment is a tremendous achievement. After all, these are two completely different dimensions: the first is based on nuclear physics and refers to the Universe at the age of 1 s, and the second - on atomic physics and the properties of the Universe at the age of 380 thousand years. Their consistency is an important test not only for our models of the evolution of space, but also for all modern physics.

Answers in a quark soup

Until the age of one microsecond, there were not even protons and neutrons; The universe was like a soup of the basic elements of nature: quarks, leptons and force carriers (photons, W and Z bosons and gluons). We are confident that this "soup with quarks" really existed, since the physical conditions of that era are now reproduced in experiments at particle accelerators (see: Ryordan M., Zeitz U. The first microseconds // VMN, No. 8, 2006).

Cosmologists hope to study that era not with the help of large and sharp-sighted telescopes, but relying on the deep ideas of elementary particle physics. The creation of the Standard Model of particle physics 30 years ago led to bold hypotheses, including string theory, which attempts to unify seemingly unrelated particles and forces. In turn, these new ideas found applications in cosmology, becoming as important as the original idea of ​​the hot Big Bang. They pointed to a deep and unexpected connection between the microcosm and the grand universe. Perhaps soon we will receive answers to three key questions: what is the nature of dark matter, what is the reason for the asymmetry between matter and antimatter, and how did the lumpy quark soup come about.

Apparently, dark matter was born in the era of the primordial quark soup. The nature of dark matter is not yet clear, but its existence is not in doubt. Our Galaxy and all other galaxies, as well as their clusters, are held together by the gravity of invisible dark matter. Whatever it is, it must interact weakly with ordinary matter, otherwise it would somehow manifest itself apart from gravity. Attempts to describe with a unified theory all the forces and particles observed in nature lead to the prediction of stable or long-lived particles that could make up dark matter. These particles may be a relic of the quark soup era and interact very weakly with atoms. One candidate is Neutralino, the lightest particle in a recently predicted class of massive copies of known particles. Neutralino should have a mass from 100 to 1000 proton masses, i.e. it should be born in experiments at the Large Hadron Collider at CERN near Geneva. In addition, trying to catch these particles from space (or the products of their interaction), physicists have created supersensitive detectors underground, and also launch them on balloons and satellites.

The second candidate is the axion, an ultralight particle with a mass about a trillion times less than that of an electron. Its existence is indicated by subtle differences predicted by the Standard Model in the behavior of quarks. Attempts to register an axion are based on the fact that in a very strong magnetic field it can turn into a photon. Both neutralino and axion have an important property: physicists call these particles "cold." Despite the fact that they are born at very high temperatures, they move slowly and therefore easily cluster into galaxies.

Probably another secret lies in the era of the primordial quark soup: why now the universe contains only matter and almost no antimatter. Physicists believe that in the beginning the Universe had equal numbers of them, but at some point a small excess of matter arose - about one extra quark for every billion antiquarks. Thanks to this imbalance in the annihilation of quarks with antiquarks during the expansion and cooling of the Universe, enough quarks have been preserved. More than 40 years ago, accelerator experiments showed that the laws of physics are arranged slightly in favor of matter; it is this small preference in the process of particle interaction at a very early stage that led to the creation of an excess of quarks.

The quark soup itself probably originated very early - about $ 10 ^ (- 34) $ s after the Big Bang, in a burst of cosmic expansion known as inflation. The reason for this surge was the energy of a new field, reminiscent of an electromagnetic field and called the inflaton. It is inflation that should explain such fundamental properties of the cosmos as its general homogeneity and small fluctuations in density that gave rise to galaxies and other structures in the Universe. When the inflaton disintegrated, it transferred its energy to quarks and other particles, thus creating the heat of the Big Bang and the quark soup itself.

Inflation theory demonstrates a deep connection between quarks and the cosmos: the quantum fluctuations of inflaton, which existed at the subatomic level, have grown to astrophysical proportions due to rapid expansion and have become the seed for all structures observed today. In other words, the picture of the microwave background radiation in the sky is a gigantic picture of the subatomic world. The observed properties of this radiation are consistent with theoretical predictions, proving that inflation, or something similar to it, did occur in the very early history of the universe.

The birth of the universe

When cosmologists try to go even further and understand the very beginning of the universe, their judgments become less certain. For a century, Einstein's general theory of relativity was the basis for studying the evolution of the universe. But it does not agree with another pillar of modern physics - quantum theory, so the most important task is to reconcile them with each other. Only with such a unified theory will we be able to move to the earliest moments of the evolution of the Universe, to the so-called Planck era with an age of $ 10 ^ (- 43) $ s, when space-time itself was formed.

Trial versions of a unified theory offer us amazing pictures of the very first moments. For example, string theory predicts the existence of extra dimensions of space and, possibly, the presence of other universes in this superspace. What we call the Big Bang could be a collision of our universe with another (see: G. Veneziano The myth of the beginning of time // VMN, No. 8, 2004)... The combination of string theory with inflation theory leads to perhaps the most ambitious idea - to the idea of ​​a multiverse, consisting of an infinite number of unconnected parts, each of which has its own physical laws. (see: R. Busso, J. Polchinski. String Theory Landscape // VMN, No. 12, 2004).

The idea of ​​a multiple universe is still in development and aims at two major theoretical problems. First, from the equations describing inflation, it follows that if it happened once, then the process will occur again and again, generating an infinite number of "bloated" regions. They are so large that they cannot communicate with each other and therefore do not affect each other. Second, string theory indicates that these regions have different physical parameters, such as the number of spatial dimensions and families of stable particles.

The concept of a multiple universe allows us to take a fresh look at two of the most complex scientific problems: what happened before the Big Bang and why are the laws of physics exactly like that? (Einstein's question, "Did God have a choice?" Related precisely to such laws.) The plural universe makes the question of what happened before the Big Bang meaningless, since there were an infinite number of big bangs, and each generated its own surge in inflation. Einstein's question also loses its meaning: in an infinite number of universes, all possible versions of the laws of physics are realized, so the laws governing our universe are not something special.

Cosmologists are ambivalent about the idea of ​​a multiple universe. If there is really no connection between the separate subuniverses, then we cannot be sure of their existence; in fact, they are beyond scientific knowledge. Part of me wants to scream, "Please, no more than one universe!" But on the other hand, the idea of ​​a multiple universe solves a number of fundamental problems. If it is correct, then the Hubble expansion of the Universe is only 100 billion times and the Copernican expulsion of the Earth from the center of the Universe in the 16th century. will seem like only a small addition to our awareness of our place in space.

IN THE DARK

The most important element of the modern understanding of the universe and its greatest mystery is dark energy, a recently discovered and deeply mysterious form of energy that causes the acceleration of cosmic expansion. Dark energy took over from matter several billion years ago. Prior to this, expansion was slowed down by the gravitational pull of matter, and gravity was able to create structures ranging from galaxies to superclusters. Now, due to the influence of dark energy, structures larger than superclusters cannot form. And if dark energy had won even earlier - say, when the universe was only 100 million years old - then the formation of structures would have stopped before galaxies arose, and we would not be here.

Cosmologists still have a very vague idea of ​​what this dark energy is. For the expansion to accelerate, a repulsive force is needed. Einstein's general theory of relativity indicates that the gravity of an extremely elastic form of energy can indeed cause repulsion. Quantum energy filling empty space does just that. But the problem is that theoretical estimates of the density of quantum energy are not consistent with the requirements of observation; in fact, they outnumber them by many orders of magnitude. Another possibility: cosmic acceleration can be controlled not by a new form of energy, but by something that imitates this energy, say, the fallacy of the general theory of relativity or the influence of invisible spatial dimensions (see: L. Cross, M. Turner The Cosmic Riddle // VMN, No. 12, 2004).

If the universe continues to accelerate at its current pace, then in 30 billion years all signs of the Big Bang will disappear. (see: L. Cross, R. Scherrer Will the End of Cosmology Come? // VMN, No. 6, 2008)... All galaxies with the exception of a few nearby will experience such a large redshift that they become invisible. The temperature of the cosmic background radiation will drop below the sensitivity of the instruments. In doing so, the universe will resemble what astronomers envisioned 100 years ago, before their instruments became powerful enough to see the universe we know today.

Modern cosmology essentially humiliates us. We are made up of protons, neutrons and electrons, which together make up only 4.5% of the universe; we exist only thanks to the subtlest connections between the smallest and the largest. The laws of microphysics ensured the dominance of matter over antimatter, the appearance of fluctuations that became seeds for galaxies, the filling of space with dark matter particles, which provided the gravitational infrastructure that allowed galaxies to form before dark energy prevailed and the expansion began to accelerate (inset above). At the same time, cosmology is inherently arrogant. The idea that we can understand something in such a vast ocean of space and time, like our Universe, at first glance seems absurd. This strange mixture of modesty and self-confidence has allowed us over the past century to move very far in understanding the structure of the modern universe and its evolution. I look forward to further progress in the coming years with optimism and am quite confident that we are living in a golden age of cosmology.

If there were even more dark energy in the universe, it would remain almost shapeless (left), without the large structures that we see (right).

Translation: V.G. Surdin

ADDITIONAL LITERATURE

• The Early Universe. Edward W. Kolb and Michael S. Turner. Westview Press, 1994.
• The Inflationary Universe. Alan Guth. Basic, 1998.
• Quarks and the Cosmos. Michael S. Turner in Science, Vol. 315, pages 59-61; January 5, 2007.
• Dark Tnergy and the Accelerating Universe. Joshua Frieman, Michael S. Turner and Dragan Huterer in Annual Reviews of Astronomy and Astrophysics, Vol. 46, pages 385-432; 2008. Available online: arxiv.org.
• Cherepashchuk A.M., Chernin A.D. Horizons of the Universe. Novosibirsk: Publishing house of the SB RAS, 2005.

Michael S. Turner pioneered the unification of particle physics, astrophysics and cosmology and led the National Academy's work in this new area of ​​research earlier this decade. He is a professor at the Kavli Foundation Institute for Cosmological Physics at the University of Chicago. From 2003 to 2006, he headed the Physics and Mathematics Division of the National Science Foundation. Among his awards are the Warner Prize of the American Astronomical Society, the Lilienfeld Prize of the American Physical Society, and the Klopsteg Prize of the American Association of Physics Teachers.

Microscopic particles, which human vision can only see with a microscope, as well as huge planets and clusters of stars, amaze people. Since ancient times, our ancestors have tried to comprehend the principles of the formation of the cosmos, but even in the modern world there is still no exact answer to the question “how the universe was formed”. Perhaps the human mind is not able to find a solution to such a global problem?

Scientists of different eras from all over the Earth tried to comprehend this secret. All theoretical explanations are based on assumptions and calculations. Numerous hypotheses put forward by scientists are designed to create an idea of ​​the Universe and explain the emergence of its large-scale structure, chemical elements and describe the chronology of origin.

String theory

To some extent refutes the Big Bang as the initial moment of the emergence of the elements of outer space. According to the universe has always existed. The hypothesis describes the interaction and structure of matter, where there is a certain set of particles, which are divided into quarks, bosons and leptons. In simple terms, these elements are the basis of the universe, since their size is so small that division into other components has become impossible.

A distinctive feature of the theory of how the universe was formed is the assertion of the aforementioned particles, which are ultramicroscopic strings that constantly vibrate. Individually, they have no material form, being the energy that together creates all the physical elements of the cosmos. An example in this situation is fire: when looking at it, it seems to be matter, but it is intangible.

The Big Bang - the first scientific hypothesis

The author of this assumption was the astronomer Edwin Hubble, who in 1929 noticed that galaxies were gradually moving away from each other. The theory states that the current large universe originated from a particle that was microscopic in size. The future elements of the universe were in a singular state, in which it was impossible to obtain data on pressure, temperature or density. The laws of physics in such conditions do not affect energy and matter.

The cause of the Big Bang is the instability that has arisen inside the particle. A kind of debris, spreading in space, formed a nebula. Over time, these tiny elements formed atoms, from which galaxies, stars and planets of the Universe emerged as we know them today.

Cosmic inflation

This theory of the birth of the Universe states that the modern world was originally placed at an infinitesimal point in a state of singularity, which began to expand at an incredible rate. After a very short period of time, its increase already exceeded the speed of light. This process was named "inflation".

The main task of the hypothesis is to explain not how the universe was formed, but the reasons for its expansion and the concept of cosmic singularity. As a result of work on this theory, it became clear that only calculations and results based on theoretical methods are applicable to solve this problem.

Creationism

This theory dominated for a long time until the end of the 19th century. According to creationism, the organic world, humanity, the Earth and the larger universe as a whole were created by God. The hypothesis originated among scientists who did not refute Christianity as an explanation for the history of the universe.

Creationism is the main enemy of evolution. All nature, created by God in six days, which we see every day, was originally like this and remains unchanged to this day. That is, self-development as such did not exist.

At the beginning of the 20th century, the acceleration of the accumulation of knowledge in the fields of physics, astronomy, mathematics and biology begins. With the help of new information, scientists make repeated attempts to explain how the universe was formed, thereby relegating creationism to the background. In the modern world, this theory has taken the form of a philosophical movement, consisting of religion as the basis, as well as myths, facts and even scientific knowledge.

Stephen Hawking's Anthropic Principle

His hypothesis as a whole can be described in a few words: there are no random events. Our Earth today has more than 40 characteristics, without which life on the planet would not exist.

The American astrophysicist H. Ross estimated the probability of random events. As a result, the scientist received the figure 10 with the degree -53 (if the last figure is less than 40, chance is considered impossible).

The observable universe contains a trillion galaxies and each of them contains approximately 100 billion stars. Based on this, the number of planets in the Universe is 10 to the twentieth power, which is 33 orders of magnitude less than in the previous calculation. Consequently, in the entire space there are no such unique places with conditions as on Earth, which would allow the spontaneous emergence of life.

The greatness and diversity of the surrounding world can amaze any imagination. All objects and objects surrounding a person, other people, various types of plants and animals, particles that can only be seen with a microscope, as well as incomprehensible star clusters: they are all united by the concept of the "Universe".

Theories of the origin of the Universe have been developed by man for a long time. Despite the absence of even the initial concept of religion or science, in the inquisitive minds of ancient people, questions arose about the principles of the world order and about what is the position of a person in the space that surrounds him. How many theories of the origin of the Universe exist today, it is difficult to count, some of them are being studied by leading world-famous scientists, others are frankly fantastic.

Cosmology and its subject

Modern cosmology - the science of the structure and development of the Universe - considers the question of its origin as one of the most interesting and still insufficiently studied mysteries. The nature of the processes that contributed to the emergence of stars, galaxies, solar systems and planets, their development, the source of the appearance of the Universe, as well as its size and boundaries: all this is just a short list of issues studied by modern scientists.

The search for answers to the fundamental riddle about the formation of the world has led to the fact that today there are various theories of the origin, existence, development of the Universe. The excitement of specialists looking for answers, constructing and testing hypotheses is justified, because a reliable theory of the birth of the Universe will reveal for all mankind the likelihood of the existence of life in other systems and planets.

Theories of the origin of the Universe have the character of scientific concepts, individual hypotheses, religious teachings, philosophical ideas and myths. They are all conditionally divided into two main categories:

1. Theories according to which the universe was created by a creator. In other words, their essence is that the process of creating the Universe was a conscious and spiritualized action, a manifestation of will
2. Theories of the origin of the Universe, built on the basis of scientific factors. Their postulates categorically reject both the existence of a creator and the possibility of conscious creation of the world. Such hypotheses are often based on what is called the principle of mediocrity. They assume the likelihood of the existence of life not only on our planet, but also on others.

Creationism - the theory of the creation of the world by the Creator

As the name suggests, creationism (creation) is a religious theory of the origin of the universe. This worldview is based on the concept of the creation of the universe, planet and man by God or the Creator.

The idea was dominant for a long time, until the end of the 19th century, when the process of accumulating knowledge in various fields of science (biology, astronomy, physics) accelerated, and the evolutionary theory became widespread. Creationism has become a kind of reaction of Christians who adhere to conservative views on the discoveries being made. The dominant idea at that time only intensified the contradictions existing between religious and other theories.

How scientific and religious theories differ

The main differences between the theories of various categories lie primarily in the terms used by their adherents. So, in scientific hypotheses, instead of the creator - nature, and instead of creation - origin. Along with this, there are questions that are covered in a similar way by different theories or even completely duplicated.

Theories of the origin of the universe, belonging to the opposite categories, date its very appearance differently. For example, according to the most common hypothesis (the big bang theory), the universe was formed about 13 billion years ago.

In contrast, the religious theory of the origin of the universe gives completely different numbers:

• According to Christian sources, the age of the universe created by God at the time of the birth of Jesus Christ was 3483-6984 years.
• Hinduism suggests that our world is roughly 155 trillion years old.

Kant and his cosmological model

Until the 20th century, most scientists were of the opinion that the universe is infinite. By this quality they characterized time and space. In addition, in their opinion, the Universe was static and homogeneous.

The idea of ​​the infinity of the Universe in space was put forward by Isaac Newton. The development of this assumption was engaged in, who developed a theory about the absence of time boundaries as well. Going further, in theoretical assumptions, Kant extended the infinity of the universe to the number of possible biological products. This postulate meant that in the conditions of an ancient and vast world without end and beginning, an innumerable number of possible options could exist, as a result of which the emergence of any biological species is real.

On the basis of the possible emergence of life forms, Darwin's theory was later developed. Observations of the starry sky and the results of calculations by astronomers confirmed Kant's cosmological model.

Einstein's Reflections

At the beginning of the 20th century, Albert Einstein published his own model of the universe. According to his theory of relativity, two opposite processes occur simultaneously in the Universe: expansion and contraction. However, he agreed with the opinion of most scientists about the stationarity of the Universe, so he introduced the concept of cosmic repulsive force. Its effect is designed to balance the attraction of the stars and to stop the process of movement of all celestial bodies in order to preserve the static nature of the Universe.

The model of the universe - according to Einstein - has a certain size, but there are no boundaries. This combination is feasible only when space is curved in the same way as it happens in a sphere.

The characteristics of the space of such a model are:

• Three-dimensionality.
• Closing oneself.
• Uniformity (lack of center and edge) in which galaxies are evenly located.

A. A. Fridman: The universe is expanding

The creator of the revolutionary expanding model of the Universe, A. A. Fridman (USSR) built his theory on the basis of equations characterizing the general theory of relativity. True, the generally accepted opinion in the scientific world of that time was the static nature of our world, therefore, due attention was not paid to his work.

A few years later, astronomer Edwin Hubble made a discovery that confirmed Friedman's ideas. The distance of galaxies from the nearby Milky Way was discovered. At the same time, the fact that the speed of their movement remains proportional to the distance between them and our galaxy has become irrefutable.

This discovery explains the constant "scattering" of stars and galaxies in relation to each other, which leads to the conclusion about the expansion of the universe.

Ultimately, Friedman's conclusions were recognized by Einstein; he later mentioned the merits of the Soviet scientist as the founder of the hypothesis of the expansion of the Universe.

It cannot be said that there are contradictions between this theory and the general theory of relativity, however, during the expansion of the Universe, there must have been an initial impulse that provoked the scattering of stars. By analogy with the explosion, the idea is called the "Big Bang".

Stephen Hawking and the anthropic principle

The anthropocentric theory of the origin of the universe was the result of calculations and discoveries by Stephen Hawking. Its creator claims that the existence of a planet so well prepared for human life cannot be accidental.

Stephen Hawking's theory of the origin of the Universe also provides for the gradual evaporation of black holes, their loss of energy and the emission of Hawking radiation.

As a result of the search for evidence, more than 40 characteristics were identified and verified, the observance of which is necessary for the development of civilization. The American astrophysicist Hugh Ross estimated the likelihood of such an unintentional coincidence. The result was 10 -53.

Our universe includes a trillion galaxies, each with 100 billion stars. According to calculations made by scientists, the total number of planets should be 10 20. This figure is 33 orders of magnitude less than previously calculated. Consequently, none of the planets in all galaxies can combine the conditions that would be suitable for the spontaneous emergence of life.

The Big Bang Theory: The Emergence of the Universe from a Tiny Particle

Scientists who support the big bang theory share the hypothesis that the universe is a consequence of a grand explosion. The main postulate of the theory is the statement that before this event, all the elements of the present Universe were enclosed in a particle of microscopic dimensions. Inside it, the elements were characterized by a singular state, in which indicators such as temperature, density and pressure could not be measured. They are endless. Matter and energy in this state are not affected by the laws of physics.

What happened 15 billion years ago is called the instability that arose inside the particle. The scattered smallest elements laid the foundation for the world we know today.

In the beginning, the universe was a nebula formed by the smallest particles (smaller than an atom). Then, when combined, they formed atoms, which served as the basis of stellar galaxies. The answer to the questions about what happened before the explosion, as well as what caused it, are the most important tasks of this theory of the origin of the Universe.

The table schematically depicts the stages of the formation of the universe after the big bang.

As follows from the above data, the Universe continues to expand and cool.

The constant increase in the distance between galaxies is the main postulate: what makes the big bang theory different. The emergence of the universe in this way can be confirmed by the evidence found. There are also grounds for refuting it.

Problems of theory

Given that the big bang theory is not proven in practice, it comes as no surprise that there are several questions that it is unable to answer:

1. Singularity. This word denotes the state of the Universe, compressed to one point. The problem of the big bang theory is the impossibility of describing the processes occurring in matter and space in such a state. The general law of relativity is not applicable here, so it is impossible to compose a mathematical description and equations for modeling.
   The fundamental impossibility of obtaining an answer to the question of the original state of the Universe discredits the theory from the very beginning. Her popular science expositions prefer to ignore or mention only in passing this complexity. However, for scientists working to provide a mathematical basis for the big bang theory, this difficulty is recognized as a major obstacle.
2. Astronomy. In this area, the big bang theory is faced with the fact that it cannot describe the process of the origin of galaxies. Based on modern versions of theories, it is possible to predict how a homogeneous gas cloud appears. Moreover, its density by the present time should be about one atom per cubic meter. To get something more, one cannot do without adjusting the initial state of the Universe. Lack of information and practical experience in this area become serious obstacles to further modeling.

There is also a discrepancy in the indicators of the calculated mass of our galaxy and those data that were obtained when studying the speed of its attraction to Apparently, the weight of our galaxy is ten times greater than previously assumed.

Cosmology and Quantum Physics

There are no cosmological theories today that do not rely on quantum mechanics. After all, she deals with the description of the behavior of atomic and The difference between quantum physics and classical (set forth by Newton) is that the second observes and describes material objects, and the first assumes an exclusively mathematical description of the observation and measurement itself. For quantum physics, material values ​​are not a subject of research, here the observer himself acts as a part of the studied situation.

Based on these features, quantum mechanics has difficulty in describing the Universe, because the observer is a part of the Universe. However, speaking about the emergence of the universe, it is impossible to imagine outside observers. Attempts to develop a model without the participation of an outside observer were crowned with the quantum theory of the origin of the Universe by J. Wheeler.

Its essence is that at every moment of time the universe splits and an infinite number of copies are formed. As a result, each of the parallel universes can be observed, and observers can see all quantum alternatives. Moreover, the original and new worlds are real.

Inflationary model

The main task that the theory of inflation is designed to solve is to find an answer to the questions that remained uncovered by the theory of the big bang and the theory of expansion. Namely:

1. Why is the universe expanding?
2. What is the Big Bang?

To this end, the inflationary theory of the origin of the Universe provides for the extrapolation of the expansion to the zero point in time, the confinement of the entire mass of the Universe at one point and the formation of a cosmological singularity, which is often called a big bang.

The irrelevance of the general theory of relativity becomes obvious, which cannot be applied at this moment. As a result, only theoretical methods, calculations and conclusions can be applied to develop a more general theory (or "new physics") and to solve the problem of cosmological singularity.

New alternative theories

Despite the success of the cosmic inflation model, there are scientists who oppose it, calling it untenable. Their main argument is the criticism of the solutions proposed by the theory. Opponents argue that the solutions obtained leave some details missing, in other words, instead of solving the problem of initial values, the theory only skillfully drapes them.

Several exotic theories are becoming an alternative, the idea of ​​which is based on the formation of initial values ​​before the big bang. New theories of the origin of the universe can be briefly described as follows:

• String theory. Its adherents propose, in addition to the usual four dimensions of space and time, to introduce additional dimensions. They could play a role in the early stages of the Universe, and at the moment be in a compactified state. Answering the question about the reason for their compactification, scientists propose an answer stating that the property of superstrings is T-duality. Therefore, the strings are "wound" on additional dimensions and their size is limited.
• Bran theory. It is also called M-theory. In accordance with its postulates, at the beginning of the formation of the Universe, there is a cold static five-dimensional space-time. Four of them (spatial) have limitations, or walls are tri-branes. Our space is one of the walls, and the second is hidden. The third tri-brane is placed in four-dimensional space, it is bound by two boundary branes. The theory considers the collision of the third brane with ours and the release of a large amount of energy. It is these conditions that become favorable for the appearance of the big bang.

1. Cyclic theories deny the uniqueness of the big bang, arguing that the universe is moving from one state to another. The problem of such theories is the increase in entropy, according to the second law of thermodynamics. Consequently, the duration of the previous cycles was shorter, and the temperature of the substance was significantly higher than in the big explosion. This is extremely unlikely.

Regardless of how many theories of the origin of the Universe there are, only two of them have stood the test of time and overcome the problem of ever-increasing entropy. They were developed by scientists Steinhardt-Türk and Baum-Frampton.

These relatively new theories of the origin of the Universe were put forward in the 80s of the last century. They have many followers who develop models based on it, search for evidence of reliability and work to eliminate contradictions.

String theory

One of the most popular among the theory of the origin of the Universe - Before proceeding to the description of its idea, it is necessary to understand the concepts of one of the closest competitors, the standard model. She suggests that matter and interactions can be described as a specific set of particles, divided into several groups:

• Quarks.
• Leptons.
• Bosons.

These particles are, in fact, the building blocks of the universe, since they are so small that they cannot be divided into components.

A distinctive feature of string theory is the assertion that such bricks are not particles, but ultramicroscopic strings that vibrate. In this case, vibrating at different frequencies, the strings become analogs of various particles described in the standard model.

To understand the theory, one should realize that strings are not any matter, they are energy. Consequently, string theory concludes that all the elements of the universe are made of energy.

Fire is a good analogy. When you look at it, you get the impression of its materiality, but it cannot be touched.

Cosmology for schoolchildren

Theories of the origin of the universe are briefly studied in schools in astronomy lessons. Students are described the basic theories about how our world was formed, what is happening to it now and how it will develop in the future.

The purpose of the lessons is to familiarize children with the nature of the formation of elementary particles, chemical elements and celestial bodies. Theories of the origin of the universe for children are reduced to the presentation of the theory of the big bang. Teachers use visual material: slides, tables, posters, illustrations. Their main task is to awaken children's interest in the world that surrounds them.