How the Universe was formed. Theories of the formation of the Universe. How and when the universe was formed. Where did the origin of the universe begin?

How did it turn into a seemingly endless space? And what will it become after many millions and billions of years? These questions have tormented (and continue to torment) the minds of philosophers and scientists, it seems, since the beginning of time, giving rise to many interesting and sometimes even crazy theories

Today, most astronomers and cosmologists have come to a general agreement that the universe as we know it was the result of a gigantic explosion that not only created the bulk of matter, but was the source of the basic physical laws according to which the cosmos that surrounds us exists. This is all called the Big Bang Theory.

The basics of the big bang theory are relatively simple. Thus, in short, according to it, all the matter that existed and now exists in the universe appeared at the same time - about 13.8 billion years ago. At that moment in time, all matter existed in the form of a very compact abstract ball (or point) with infinite density and temperature. This state was called singularity. Suddenly, the singularity began to expand and gave birth to the universe we know.

It is worth noting that the big bang theory is only one of many proposed hypotheses for the origin of the universe (for example, there is also the theory of a stationary universe), but it has received the widest recognition and popularity. Not only does it explain the source of all known matter, the laws of physics, and the larger structure of the universe, it also describes the reasons for the expansion of the universe and many other aspects and phenomena.

Chronology of events in the big bang theory.

Based on knowledge of the current state of the universe, scientists theorize that everything must have started from a single point with infinite density and finite time, which began to expand. After the initial expansion, the theory goes, the universe went through a cooling phase that allowed the emergence of subatomic particles and later simple atoms. Giant clouds of these ancient elements later, thanks to gravity, began to form stars and galaxies.

All this, according to scientists, began about 13.8 billion years ago, and therefore this starting point is considered the age of the universe. By exploring various theoretical principles, conducting experiments involving particle accelerators and high-energy states, and conducting astronomical studies of the far reaches of the universe, scientists have deduced and proposed a chronology of events that began with the big bang and led the universe ultimately to that state of cosmic evolution that is taking place now.

Scientists believe that the earliest periods of the universe's origins - lasting from 10-43 to 10-11 seconds after the big bang - are still a matter of debate and debate. Attention! Only if we take into account that the laws of physics that we now know could not exist at that time, then it is very difficult to understand how the processes in this early universe were regulated. In addition, experiments using the possible types of energies that could be present at that time have not yet been carried out. Be that as it may, many theories about the origin of the universe ultimately agree that at some point in time there was a starting point from which everything began.

The era of singularity.

Also known as the Planck epoch (or Planck era), it is taken to be the earliest known period in the evolution of the universe. At this time, all matter was contained in a single point of infinite density and temperature. During this period, scientists believe, the quantum effects of gravitational interactions dominated the physical ones, and no physical force was equal in strength to gravity.

The Planck era supposedly lasted from 0 to 10-43 seconds and is so named because its duration can only be measured by Planck time. Due to the extreme temperatures and infinite density of matter, the state of the universe during this time period was extremely unstable. This was followed by periods of expansion and cooling that gave rise to the fundamental forces of physics.

Approximately in the period from 10-43 to 10-36 seconds, a process of collision of transition temperature states occurred in the universe. It is believed that it was at this point that the fundamental forces that govern the current universe began to separate from each other. The first step of this separation was the emergence of gravitational forces, strong and weak nuclear interactions and electromagnetism.

In the period from about 10-36 to 10-32 seconds after the big bang, the temperature of the universe became low enough (1028 K), which led to the separation of electromagnetic forces (the strong force) and the weak nuclear force (the weak force).

The era of inflation.

With the advent of the first fundamental forces in the universe, the era of inflation began, which lasted from 10-32 seconds in Planck time to an unknown point in time. Most cosmological models suggest that the universe during this period was uniformly filled with high-density energy, and incredibly high temperatures and pressures caused it to rapidly expand and cool.

This began at 10-37 seconds, when the transition phase that caused the separation of forces was followed by the expansion of the universe in geometric progression. During the same period of time, the universe was in a state of baryogenesis, when the temperature was so high that the random movement of particles in space occurred at near-light speed.

At this time, pairs of particles - antiparticles are formed and immediately colliding and destroyed, which is believed to have led to the dominance of matter over antimatter in the modern universe. After the end of inflation, the universe consisted of quark-gluon plasma and other elementary particles. From that moment on, the universe began to cool down, matter began to form and combine.

The era of cooling.

As the density and temperature inside the universe decreased, the energy in each particle began to decrease. This transitional state lasted until the fundamental forces and elementary particles arrived at their present form. Since the energy of the particles has dropped to values ​​​​that can be achieved today in experiments, the actual possible existence of this time period is much less controversial among scientists.

For example, scientists believe that at 10-11 seconds after the big bang, the energy of the particles decreased significantly. At about 10-6 seconds, quarks and gluons began to form baryons - protons and neutrons. Quarks began to predominate over antiquarks, which in turn led to the predominance of baryons over antibaryons.

Since the temperature was no longer high enough to create new proton-antiproton pairs (or neutron-antineutron pairs), massive destruction of these particles followed, resulting in the remainder of only 1/1010 of the number of original protons and neutrons and the complete disappearance of their antiparticles. A similar process occurred about 1 second after the big bang. Only the “Victims” this time were electrons and positrons. After the mass destruction, the remaining protons, neutrons and electrons ceased their random motion, and the energy density of the universe was filled with photons and, to a lesser extent, neutrinos.

During the first minutes of the expansion of the universe, a period of nucleosynthesis (the synthesis of chemical elements) began. With the temperature dropping to 1 billion kelvins and the energy density decreasing to values ​​approximately equivalent to that of air, neutrons and protons began to mix and form the first stable isotope of hydrogen (deuterium), and helium atoms. However, most of the protons in the universe remained as the disconnected nuclei of hydrogen atoms.

After about 379,000 years, the electrons combined with these hydrogen nuclei to form atoms (again predominantly hydrogen), while the radiation separated from matter and continued to expand virtually unimpeded through space. This radiation is called the cosmic microwave background radiation, and it is the oldest source of light in the universe.

With expansion, the cosmic microwave background gradually lost its density and energy, and at the moment its temperature is 2.7260 0.0013 K (- 270.424 C), and the energy density is 0.25 eV (or 4.005x10-14 J/m? ; 400-500 Photons/cm. The CMB extends in all directions and over a distance of about 13.8 billion light years, but estimates of its actual distribution indicate approximately 46 billion light years from the center of the universe.

The era of structure (hierarchical era).

Over the next few billion years, denser regions of matter that were almost evenly distributed throughout the universe began to attract each other. As a result of this, they became even denser and began to form clouds of gas, stars, galaxies and other astronomical structures that we can observe today. This period is called the hierarchical era. At this time, the universe that we see now began to take its form. Matter began to unite into structures of various sizes - stars, planets, galaxies, galaxy clusters, as well as galactic superclusters, separated by intergalactic bridges containing only a few galaxies.

The details of this process can be described according to the idea of ​​the amount and type of matter distributed in the universe, which is represented as cold, warm, hot dark matter and baryonic matter. However, the current standard cosmological model of the big bang is the lambda-CDM model, according to which dark matter particles move slower than the speed of light. It was chosen because it solves all the contradictions that appeared in other cosmological models.

According to this model, cold dark matter accounts for about 23 percent of all matter/energy in the universe. The proportion of baryonic matter is about 4.6 percent. Lambda - CDM refers to the so-called cosmological constant: a theory proposed by Albert Einstein that characterizes the properties of the vacuum and shows the balance relationship between mass and energy as a constant static quantity. In this case, it is associated with dark energy, which serves as an accelerator of the expansion of the universe and keeps giant cosmological structures largely homogeneous.

Long-term forecasts regarding the future of the universe.

Hypotheses that the evolution of the universe has a starting point naturally lead scientists to questions about the possible end point of this process. Only if the universe began its history from a small point with infinite density, which suddenly began to expand, does this not mean that it will also expand indefinitely, or one day it will run out of expansive force and the reverse process of compression will begin, the end result of which will it still be the same infinitely dense point?

Answering these questions has been the main goal of cosmologists from the very beginning of the debate about which cosmological model of the universe is correct. With the acceptance of the Big Bang theory, but largely thanks to the observation of dark energy in the 1990s, scientists have come to agree on the two most likely scenarios for the evolution of the universe.

According to the first, called the Big Crunch, the universe will reach its maximum size and begin to collapse. This scenario will be possible only if the mass density of the universe becomes greater than the critical density itself. In other words, if the density of matter reaches or rises above a certain value (1-3x10-26 kg of matter per m), the universe will begin to contract.

An alternative is another scenario, which states that if the density in the universe is equal to or below the critical density value, then its expansion will slow down, but will never completely stop. According to this hypothesis, called the "Heat Death of the Universe", expansion will continue until star formation stops consuming the interstellar gas inside each of the surrounding galaxies. That is, the transfer of energy and matter from one object to another will completely stop. All existing stars in this case will burn out and turn into white dwarfs, neutron stars and black holes.

Gradually, black holes will collide with other black holes, leading to the formation of larger and larger ones. The average temperature of the universe will approach absolute zero. Black holes will eventually "Evaporate", releasing their last hawking radiation. Eventually, thermodynamic entropy in the universe will reach its maximum. Heat death will occur.

Modern observations that take into account the presence of dark energy and its influence on the expansion of space have led scientists to conclude that over time, more and more of the universe will pass beyond our event horizon and become invisible to us. The final and logical result of this is not yet known to scientists, but “Heat Death” may well be the end point of such events.

There are other hypotheses regarding the distribution of dark energy, or more precisely, its possible types (for example, phantom energy. According to them, galactic clusters, stars, planets, atoms, atomic nuclei and matter itself will be torn apart as a result of its endless expansion. Such a scenario evolution is called the “Big Rip”. The cause of the death of the universe according to this scenario is the expansion itself.

History of the Big Bang Theory.

The earliest mention of the big bang dates back to the early 20th century and is associated with observations of space. In 1912, American astronomer Vesto Slifer made a series of observations of spiral galaxies (which were originally thought to be nebulae) and measured their Doppler redshift. In almost all cases, observations have shown that spiral galaxies are moving away from our Milky Way.

In 1922, the outstanding Russian mathematician and cosmologist Alexander Friedman derived the so-called Friedmann equations from Einstein’s equations for general relativity. Despite Einstein's promotion of a theory in favor of a cosmological constant, Friedman's work showed that the universe was rather in a state of expansion.

In 1924, Edwin Hubble's measurements of the distance to a nearby spiral nebula showed that these systems were in fact truly different galaxies. At the same time, Hubble began developing a series of distance subtraction metrics using the 2.5-meter Hooker Telescope at Mount Wilson Observatory. By 1929, Hubble had discovered a relationship between the distance and the speed at which galaxies recede, which later became Hubble's law.

In 1927, the Belgian mathematician, physicist and Catholic priest Georges Lemaître independently arrived at the same results as Friedmann's equations, and was the first to formulate the relationship between the distance and speed of galaxies, offering the first estimate of the coefficient of this relationship. Lemaitre believed that at some point in the past the entire mass of the universe was concentrated at one point (atom.

These discoveries and assumptions caused much debate among physicists in the 20s and 30s, most of whom believed that the universe was in a stationary state. According to the model that was established at that time, new matter was created along with the infinite expansion of the universe, distributed evenly and equally in density throughout its entire extent. Among the scientists who supported it, the big bang idea seemed more theological than scientific. The Lemaitre was criticized for being biased on the basis of religious prejudices.

It should be noted that other theories existed at the same time. For example, the Milne model of the universe and the cyclic model. Both were based on the postulates of Einstein’s general theory of relativity and subsequently received the support of the scientist himself. According to these models, the universe exists in an endless stream of repeating cycles of expansion and collapse.

1. The era of singularity (Planckian). It is considered to be primary, as the early evolutionary period of the Universe. Matter was concentrated at one point, which had its own temperature and infinite density. Scientists argue that this era is characterized by the dominance of quantum effects belonging to gravitational interaction over physical ones, and not a single physical force that existed in those distant times was identical in strength to gravity, that is, it was not equal to it. The duration of the Planck era is concentrated in the range from 0 to 10-43 seconds. It received this name because only Planck time could fully measure its extent. This time interval is considered to be very unstable, which in turn is closely related to the extreme temperature and limitless density of matter. Following the era of singularity, a period of expansion occurred, and with it cooling, which led to the formation of basic physical forces.

How the Universe was born. Cold birth

What happened before the Universe? Model of the "Sleeping" Universe

“Perhaps before the Big Bang the Universe was a very compact, slowly evolving static space,” theorize physicists such as Kurt Hinterbichler, Austin Joyce and Justin Khoury.

This “pre-explosion” Universe had to have a metastable state, that is, be stable until an even more stable state appears. By analogy, imagine a cliff, on the edge of which there is a boulder in a state of vibration. Any contact with the boulder will lead to it falling into the abyss or - which is closer to our case - a Big Bang will occur. According to some theories, the “pre-explosion” Universe could exist in a different form, for example, in the form of an oblate and very dense space. As a result, this metastable period came to an end: it expanded sharply and acquired the shape and state of what we see now.

“The sleeping universe model, however, also has its problems,” says Carroll.

“It also assumes that our Universe has a low level of entropy, but does not explain why this is so.”

However, Hinterbichler, a theoretical physicist at Case Western Reserve University, doesn't see the appearance of low entropy as a problem.

“We are simply looking for an explanation of the dynamics that occurred before the Big Bang that explain why we see what we see now. For now, this is the only thing we have left,” says Hinterbichler.

Carroll, however, believes that there is another theory of a “pre-explosion” Universe that can explain the low level of entropy present in our Universe.

How the Universe appeared from nothing. How the Universe works

Let's talk about how physics actually works, according to our concepts. Since the time of Newton, the paradigm of fundamental physics has not changed; it includes three parts. The first is “state space”: essentially a list of all the possible configurations in which the Universe could exist. The second is a certain state that represents the Universe at some point in time, usually the current one. The third is a certain rule according to which the Universe develops in time. Give me the Universe today, and the laws of physics will tell you what will happen to it in the future. This way of thinking is no less true for quantum mechanics or general relativity or quantum field theory than for Newtonian mechanics or Maxwellian electrodynamics.

Quantum mechanics, in particular, is a special, but very versatile implementation of this scheme. (Quantum field theory is just a specific example of quantum mechanics, not a new way of thinking). States are “wave functions”, and the set of all possible wave functions of a particular system is called “Hilbert space”. Its advantage is that it greatly limits the set of possibilities (because it is a vector space: a note for experts). Once you tell me its size (number of dimensions), you will completely define your Hilbert space. This is radically different from classical mechanics, in which the state space can become extremely complex. And there is also a machine - the “Hamiltonian” - which indicates exactly how to develop from one state to another over time. I repeat that there are not many varieties of Hamiltonians; it is enough to write down a certain list of quantities (eigenvalues ​​of energy - clarification for you, annoying experts).

How life appeared on Earth. Life in the Earth

Life using chemistry different from ours may arise on Earth more than once. Maybe. And if we find evidence of such a process, it means that there is a high probability that life will arise in many places in the Universe independently of each other, just as life arose on Earth. But on the other hand, imagine how we would feel if we eventually discovered life on another planet, perhaps orbiting a distant star, and it turned out to have identical chemistry and perhaps even an identical DNA structure to ours.

The chances that life on Earth arose completely spontaneously and by chance seem very small. The chances of exactly the same life arising in another place are incredibly small, and practically equal to zero. But there are possible answers to these questions, which the English astronomers Fred Hoyle and Chandra Wickramasinghe outlined in their unusual book, written in 1979, Life cloud.

Given the extremely unlikely chance that life on Earth appeared on its own, the authors propose another explanation. It lies in the fact that the emergence of life occurred somewhere in space, and then spread throughout the Universe through panspermia. Microscopic life trapped in debris from cosmic collisions can travel while dormant for very long periods of time. After which, when it arrives at its destination, where it will begin to develop again. Thus, all life in the Universe, including life on Earth, is in fact the same life.

Video How the Universe appeared

How the Universe appeared from nothing. Cold birth

However, the path to such a unification can be thought out at a qualitative level, and very interesting prospects arise here. One of them was considered by the famous cosmologist, professor at the University of Arizona Lawrence Krauss in his recently published book “A Universe From Nothing”. His hypothesis looks fantastic, but does not at all contradict the established laws of physics.

It is believed that our Universe arose from a very hot initial state with a temperature of about 1032 Kelvin. However, it is also possible to imagine the cold birth of universes from pure vacuum - more precisely, from its quantum fluctuations. It is well known that such fluctuations give rise to a great many virtual particles that literally arose from nothingness and subsequently disappeared without a trace. According to Krauss, vacuum fluctuations are, in principle, capable of giving rise to equally ephemeral protouniverses, which, under certain conditions, pass from a virtual state to a real one.

The question of how the Universe came into being has always worried people. This is not surprising, because everyone wants to know their origins. Scientists, priests and writers have been struggling with this question for several millennia. This question excites the minds of not only specialists, but also every ordinary person. However, it’s worth saying right away that there is no 100% answer to the question of how the Universe came into being. There is only a theory that is supported by most scientists.

• Here we will analyze it.

Since everything that surrounds man has its own beginning, it is not surprising that since ancient times man has been trying to find the beginning of the Universe. For a man of the Middle Ages, the answer to this question was quite simple - God created the Universe. However, with the development of science, scientists began to question not only the question of God, but also the idea that the Universe had a beginning.

In 1929, thanks to the American astronomer Hubble, scientists returned to the question of the roots of the Universe. The fact is that Hubble proved that the galaxies that make up the Universe are constantly moving. In addition to movement, they can also increase, which means the Universe increases. And if it grows, it turns out that there was once a stage of the start of this growth. This means that the Universe has a beginning.

A little later, the British astronomer Hoyle put forward a sensational hypothesis: the Universe arose at the moment of the Big Bang. His theory went down in history under that name. The essence of Hoyle's idea is simple and complex at the same time. He believed that there once existed a stage called the state of cosmic singularity, that is, time stood at zero, and density and temperature were equal to infinity. And at one moment there was an explosion, as a result of which the singularity was broken, and therefore the density and temperature changed, the growth of matter began, which means time began to count. Later, Hoyle himself called his theory unconvincing, but this did not stop it from becoming the most popular hypothesis of the origin of the Universe.

When did what Hoyle called the Big Bang happen? Scientists carried out many calculations, as a result, most agreed on the figure of 13.5 billion years. It was then that the Universe began to appear out of nothing. In just a split second, the Universe acquired a size smaller than an atom, and the process of expansion was launched. Gravity played a key role. The most interesting thing is that if it had been a little stronger, then nothing would have arisen, at most a black hole. And if gravity were a little weaker, then nothing would arise at all.
A few seconds after the Explosion, the temperature in the Universe decreased slightly, which gave impetus to the creation of matter and antimatter. As a result, atoms began to appear. So the Universe ceased to be monochromatic. Somewhere there were more atoms, somewhere less. In some parts it was hotter, in others the temperature was lower. Atoms began to collide with each other, forming compounds, then new substances, and later bodies. Some objects had great internal energy. These were the stars. They began to gather around themselves (thanks to the force of gravity) other bodies that we call planets. This is how systems arose, one of which is our Solar system.

Big Bang. Model problems and their resolution

1. The problem of the large scale and isotropy of the Universe can be resolved due to the fact that during the inflation stage the expansion occurred at an unusually high rate. It follows from this that the entire space of the observable Universe is the result of one causally related region of the epoch preceding the inflationary one.
2. Solving the problem of a flat Universe. This is possible because at the inflation stage the radius of curvature of space increases. This value is such that it allows modern density parameters to have a value close to critical.
3. Inflationary expansion leads to the emergence of density fluctuations with a certain amplitude and spectrum shape. This makes it possible for these oscillations (fluctuations) to develop into the current structure of the Universe, while maintaining large-scale homogeneity and isotropy. This is a solution to the problem of the large-scale structure of the Universe.

The main disadvantage of the inflation model can be considered its dependence on theories that have not yet been proven and are not fully developed.

For example, the model is based on the unified field theory, which is still just a hypothesis. It cannot be tested experimentally in laboratory conditions. Another drawback of the model is the incomprehensibility of where the superheated and expanding matter came from. Three possibilities are considered here:

1. The standard Big Bang theory suggests the onset of inflation at a very early stage in the evolution of the Universe. But then the problem of singularity is not resolved.
2. The second possibility is the emergence of the Universe from chaos. Different parts of it had different temperatures, so compression occurred in some places, and expansion in others. Inflation would have occurred in a region of the Universe that was overheated and expanding. But it is not clear where the primary chaos came from.
3. The third option is the quantum mechanical path, through which a clump of superheated and expanding matter arose. In fact, the Universe came into being out of nothing.

Completed by student group PI-05-1: Tsaaeva D.B.

Grozny State Oil Institute
named after Academician M.D. Millionshchikova

This work gives a description of what the scientific picture of the world is, and also gives a brief description of the idea of ​​the Universe (Our idea of ​​the Universe, the Birth of the Universe, etc.).

This work includes 10 pages.

The scientific picture of the world is a holistic system of ideas about the general properties and patterns of reality, built as a result of generalization and synthesis of fundamental scientific concepts and principles.

The scientific picture of the world differs significantly from religious ideas about the world, which are based not so much on proven facts, but on the authority of the prophets and religious tradition. Religious interpretations of the concept of the universe are constantly changing to bring them closer to modern scientific interpretations. Thus, just a few hundred years ago, Christians, literally interpreting the Bible, believed that the sky was solid (“firmament”), and Muslims, according to the Koran, believed that the Sun set in a “muddy well.” The dogmas of different religions, as a rule, contradict each other, and these contradictions are very difficult to overcome (unlike scientific contradictions, which are overcome experimentally).

Once a famous scientist (they say it was Bertrand Russell) gave a public lecture on astronomy. He told how the Earth revolves around the Sun, and the Sun, in turn, revolves around the center of a huge cluster of stars called our Galaxy. When the lecture came to an end, a small old lady stood up from the back rows of the hall and said: “Everything you told us is nonsense. In fact, our world is a flat plate that stands on the back of a giant turtle.” Smiling indulgently, the scientist asked: “What does the turtle support?” “You are very smart, young man,” answered the old lady. “A turtle is on another turtle, that one is also on a turtle, and so on lower and lower.”

This idea of ​​the Universe as an endless tower of turtles will seem funny to most of us, but why do we think that we ourselves know better? What do we know about the Universe, and how did we know it? Where did the Universe come from and what will happen to it? Did the Universe have a beginning, and if so, what happened before the beginning? What is the essence of time? Will it ever end? The achievements of physics in recent years, which we partially owe to fantastic new technology, make it possible to finally obtain answers to at least some of these long-standing questions. As time passes, these answers may become as obvious as the fact that the Earth revolves around the Sun, and perhaps as ridiculous as a tower of turtles. Only time (whatever that is) will decide.

According to cosmological data, the Universe arose as a result of an explosive process called the Big Bang, which occurred about 14 billion years ago. The Big Bang theory fits well with observed facts (for example, the expansion of the Universe and the dominance of hydrogen) and allowed us to make correct predictions, in particular, about the existence and parameters of the cosmic microwave background radiation.

At the moment of the Big Bang, the Universe occupied microscopic, quantum dimensions.

According to the inflationary model, in the initial stage of its evolution the Universe experienced a period of accelerated expansion (inflation). It is assumed that at this moment the Universe was “empty and cold” (only a high-energy scalar field existed) and then filled with hot matter that continued to expand.

The transition of energy into mass does not contradict physical laws; for example, the birth of a particle-antiparticle pair from a vacuum can still be observed in some scientific experiments.

One of the most important properties of the Universe is that it is expanding, and at an accelerated rate. The further an object is from our galaxy, the faster it moves away from us (but this does not mean that we are in the center of the world: the same is true for any point in space).

Visible matter in the Universe is structured into star clusters - galaxies. Galaxies form groups, which, in turn, are included in superclusters of galaxies. Superclusters are concentrated mainly inside flat layers, between which there is a space practically free of galaxies. Thus, on a very large scale, the Universe has a cellular structure, reminiscent of the spongy structure of bread. However, at even greater distances (over 1 billion light years), matter in the Universe is distributed uniformly.

If you look at the sky on a clear, moonless night, the brightest objects you'll see are likely to be the planets Venus, Mars, Jupiter and Saturn. In addition, you will see a huge number of stars similar to our Sun, but located much further from us. As the Earth orbits the Sun, some of these “fixed” stars slightly change their position relative to each other, meaning they are not actually stationary at all!

The fact is that they are somewhat closer to us than others. Since the Earth revolves around the Sun, nearby stars are visible all the time at different points in the background of more distant stars. Thanks to this, it is possible to directly measure the distance from us to these stars: the closer they are, the more noticeable their movement.

It’s interesting what the general state of scientific thought was like before the beginning of the 20th century: it never occurred to anyone that the Universe could expand or contract. Everyone believed that the Universe either always existed in an unchanged state, or was created at some point in time in the past approximately as it is now. This may be partly explained by the tendency of people to believe in eternal truths, and also by the special attraction of the idea that, even if they themselves grow old and die, the Universe will remain eternal and unchanged.

Gorelov A.A. Concepts of modern natural science. – M.: Center, 2002. – 208 p.

Kanke V.A. Concepts of modern natural science. Textbook for universities. Ed. 2nd, rev. – M.: Logos, 2003. – 368 p.

Karpenkov S.Kh. Concepts of modern natural science. State Unitary Enterprise "Publishing House", "Higher School", 2001.

After the mysterious cosmological singularity comes the no less mysterious Planck era (0 -10 -43 s). It is difficult to say what processes took place in this brief moment of the newborn Universe. But it is known for sure that by the end of the Planck moment, the gravitational influence was separated from the three fundamental forces, united into a single group of the Great Unification.

In order to describe the earlier moment, a new theory is needed, part of which could be the model of loop quantum gravity and string theory. It turns out that the Planck era, like the cosmological singularity, constitutes an extremely short gap in duration, but significant in scientific weight, in the available knowledge of the early Universe. Also within the Planck time there were peculiar fluctuations of space and time. To describe this quantum chaos, we can use the image of foaming quantum cells of space-time.

Compared to the Planck era, further events appear before us in a bright and understandable light. In the period from 10 -43 s to 10 -35 s, the forces of gravity and the Great Unification were already operating in the young Universe. During this period, strong, weak and electromagnetic influences were one and formed the force field of the Great Unification.

When 10 -35 s had passed since the Big Bang, the Universe reached a temperature of 10 29 K. At this moment, the strong interaction separated from the electroweak interaction. This led to symmetry breaking, which occurred differently in different parts of the Universe. There is a possibility that the Universe was divided into parts that were fenced off from each other by space-time defects. Other defects could also exist there - cosmic strings or magnetic monopoles. However, today we cannot see this because of another division of the power of the Grand Unification - cosmological inflation.

At that time, the Universe was filled with a gas of gravitons - hypothetical quanta of the gravitational field and bosons of the Grand Unified force. At the same time, there was almost no difference between leptons and quarks.

When there was a separation of forces in some parts of the Universe, a false vacuum was created. The energy is stuck at a high level, forcing space to double every 10 -34 s. Thus, the Universe moved from quantum scales (one billionth of a trillionth of a trillionth of a centimeter) to the size of a ball with a diameter of about 10 cm. As a result of the era of the Great Unification, a phase transition of primary matter occurred, which was accompanied by a violation of the uniformity of its density. The era of the Great Unification ended approximately 10?34 seconds from the moment of the Big Bang, when the density of matter was 10 74 g/cm³ and the temperature was 10 27 K. At this point in time, the strong nuclear interaction is separated from the primary interaction, which begins to play an important role in the created conditions. This separation led to the next phase transition and large-scale expansion of the Universe, which led to a change in the density of matter and its distribution throughout the Universe.

One of the reasons why we know so little about the state of the Universe before inflation is that subsequent events changed it greatly, scattering pre-inflationary particles to the farthest corners of the Universe. Therefore, even if these particles have been preserved, detecting them in modern matter is quite difficult.

With the rapid development of the Universe, great changes are occurring, and following the period of the Great Unification comes the era of inflation (10 -35 - 10 -32). This era is characterized by ultra-fast expansion of the young Universe, that is, inflation. At that brief moment, the Universe was an ocean of false vacuum with a high energy density, thanks to which expansion became possible. At the same time, the vacuum parameters were constantly changing due to quantum bursts - fluctuations (space-time foaming).

Inflation explains the nature of the explosion during the Big Bang, that is, why the rapid expansion of the Universe occurred. The basis for describing this phenomenon was Einstein's general theory of relativity and quantum field theory. In order to describe this phenomenon, physicists built a hypothetical inflator field that filled all space. Thanks to random fluctuations, it took on different values ​​in arbitrary spatial regions and at different times. Then a homogeneous configuration of a critical size was formed in the inflator field, after which the spatial region occupied by the fluctuation began to rapidly increase in size. Due to the desire of the inflator field to occupy a position in which its energy is minimal, the expansion process acquired an increasing character, as a result of which the Universe began to increase in size. At the moment of expansion (10 -34), the false vacuum began to disintegrate, as a result of which particles and antiparticles of high energies begin to form.

The hadron era is beginning in the history of the Universe, an important feature of which is the existence of particles and antiparticles. According to modern concepts, in the first microseconds after the Big Bang, the Universe was in a state of quark-gluon plasma. Quarks are components of all hadrons (protons and neutrons), and neutral particles, gluons, are carriers of the strong interaction, which ensure the sticking of quarks into hadrons. In the first moments of the Universe, these particles were just being formed and were in a free, gaseous state.

The chromoplasm of quarks and gluons is usually compared to the liquid state of interacting matter. In this phase, quarks and gluons are freed from hadronic matter and can move freely throughout the plasma space, resulting in the formation of color conductivity.

Despite the extremely high temperatures, the quarks were quite bound together, and their movement resembled the movement of atoms in a liquid rather than in a gas. Also, under such conditions, another phase transition occurs, in which the light quarks that make up the matter become massless.

Observations of the CMB showed that the initial abundance of particles compared to the number of antiparticles was a negligible fraction of the total. And it was these excess protons that were enough to create the matter of the Universe.

Some scientists believe that there was also the hiding of matter in the hadron era. The carrier of the hidden mass is unknown, but elementary particles such as axions are considered the most probable.

As the explosion progressed, the temperature dropped and after one tenth of a second reached 3*10 10 degrees Celsius. In one second - ten thousand million degrees, and in thirteen seconds - three thousand million. This was already enough for electrons and positrons to begin to annihilate faster. The energy released during annihilation gradually slowed down the rate of cooling of the Universe, but the temperature continued to fall.

The period from 10-4 - 10 s is usually called the era of leptons. When the energy of particles and photons decreased a hundred times, the matter was filled with leptons-electrons and positrons. The lepton era begins with the decay of the last hadrons into muons and muon neutrinos, and ends a few seconds later, when the photon energy sharply decreased and the generation of electron-positron pairs stopped.

About one hundredth of a second after the Big Bang, the temperature of the Universe was 10 11 degrees Celsius. This is much hotter than the center of any star we know of. This temperature is so high that none of the components of ordinary matter, atoms and molecules, could exist. Instead, the young Universe consisted of elementary particles. One of these particles were electrons, negatively charged particles that form the outer parts of all atoms. The other particles were positrons, positively charged particles with a mass exactly equal to the mass of an electron. In addition, there were neutrinos of various types - ghostly particles that had neither mass nor electrical charge. But neutrinos and antineutrinos did not annihilate each other, because these particles interact very weakly with each other and with other particles. Therefore, they should still be found around us, and they could be a good way to test a model of a hot early Universe. However, the energies of these particles are now too low to observe them.

During the era of leptons, there were particles such as protons and neutrons. And finally, there was light in the Universe, which, according to quantum theory, consists of photons. Proportionally, there are a thousand million electrons per neutron and proton. All these particles were continuously born from pure energy, and then annihilated, forming other types of particles. The density in the early Universe at such high temperatures was four thousand million times greater than that of water.

As mentioned earlier, it is during this period that intensive production of various types of ghost neutrinos, which are called relict neutrinos, occurs in nuclear reactions.

The radiation era begins, at the beginning of which the Universe enters the era of radiation. At the beginning of the era (10 s), radiation intensively interacted with charged particles of protons and electrons. Due to the drop in temperature, the photons cooled, and as a result of numerous scatterings on receding particles, part of their energy was carried away.

About a hundred seconds after the Big Bang, the temperature drops to a thousand million degrees, which is the temperature of the hottest stars. Under such conditions, the energy of protons and neutrons is no longer enough to resist strong nuclear attraction, and they begin to combine with each other, forming nuclei of deuterium - heavy hydrogen. Deuterium nuclei then attach other neutrons and protons and become helium nuclei. Afterwards, heavier elements are formed - lithium and beryllium. The primary formation of atomic nuclei of the nascent substance did not last long. After three minutes, the particles had scattered so far apart that collisions became rare. According to the hot Big Bang model, about a quarter of the protons and neutrons would have turned into atoms of helium, hydrogen and other elements. The remaining elementary particles decayed into protons, representing the nuclei of ordinary hydrogen.

A few hours after the Big Bang, the formation of helium and other elements stopped. For a million years, the Universe simply continued to expand and almost nothing else happened. The matter existing at that time began to expand and cool. Much later, after hundreds of thousands of years, the temperature dropped to several thousand degrees, and the energy of electrons and nuclei became insufficient to overcome the electromagnetic attraction acting between them. They began to collide with each other, forming the first atoms of hydrogen and helium (Figure 2).

Cosmologists continue to advance towards a final understanding of the processes that created and shaped the Universe.

The universe is so vast in space and time that for most of human history it remained inaccessible to both our instruments and 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, which opened us to galaxies beyond the Milky Way, 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 dark energy exists. Bold ideas about cosmic inflation and the multiplicity of universes were born.

A hundred years ago, the Universe was simpler: eternal and unchanging, consisting of a single galaxy containing several million visible stars. The modern picture is much more complex and much richer. The cosmos arose 13.7 billion years ago as a result of the Big Bang. A split second after the beginning, the Universe was a hot, formless mixture of elementary particles - quarks and leptons. As it expanded and cooled, structures emerged step by step: neutrons and protons, atomic nuclei, atoms, stars, galaxies, galaxy clusters and, finally, superclusters. The observable Universe now contains 100 billion galaxies, each containing about 100 billion stars and probably as many planets. The galaxies themselves are held back from expansion by the gravity of mysterious dark matter. And the Universe continues to expand and even does so 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 the primitive quark "soup" to the increasing complexity of galaxies, stars, planets and life observed today. These structures appeared one after another over billions of years, obeying the basic laws of physics. Traveling back in time to the era of origin, 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 not yet clearly confirmed) and , finally, to the very moment of birth (about which there are still only guesses). Although we do not yet fully understand how the Universe was born, we already have amazing hypotheses, such as the concept of a multiple universe, including an infinite number of unrelated subuniverses.

BASIC POINTS

• 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 the modern highly structured cosmos.
• 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 - the unknown substance that holds this structure.
• The future of the Universe is determined by dark energy - an unknown form of energy that is causing 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 vague nebulae, which remained mysterious for several centuries, were galaxies like ours. Thus, Hubble increased our understanding of the Universe by 100 billion times! And a few years later he proved that galaxies are moving away from each other, obeying a mathematical pattern now known as Hubble's law: the further away a galaxy is, the faster it moves. It is from this law that it follows that the Big Bang took place 13.7 billion years ago.

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

Within the framework of the general theory of relativity, Hubble's law is interpreted as follows: space itself is expanding, and galaxies are moving along with it (Fig. above). Light also stretches, experiencing a red shift, which means losing energy, so the Universe cools as it expands. Cosmic expansion helps to understand how the modern Universe was formed. If you mentally rush into the past, 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 find themselves in the past - and the larger the telescope, the deeper their gaze penetrates. Light coming from distant galaxies shows us ancient times, and its redshift shows how much the Universe has expanded over time. The current record redshift observed is about eight, which means that this light was emitted when the size of the Universe was nine times smaller than it is today, and its age was only a few hundred million years. Instruments such as the Hubble Space Telescope and the 10-meter Keck Telescopes on Mauna Kea easily take us back to the formation of galaxies like ours, several billion years after the Big Bang. Light from earlier eras is so red-shifted that astronomers are forced to detect it in infrared and radio wavelengths. Telescopes under construction, such as the 6.5 m infrared James Webb 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 first stars and galaxies.

Computer modeling shows that these stars and galaxies appeared when the age of the Universe was about 100 million years. Before this, the universe went through a period called the dark era, when it was pitch black. The space was filled with a formless mass of five parts dark matter and one part hydrogen and helium, which became rarefied as the Universe expanded. The matter was slightly inhomogeneous in density, and gravity acted as an amplifier for these inhomogeneities: denser regions expanded more slowly than less dense ones. By the time of 100 million years, the densest regions not only slowed down their expansion, but even began to shrink. 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 dark matter, which, as its name suggests, is incapable of emitting or absorbing light. Therefore, it formed very extended clouds. On the other hand, hydrogen and helium, emitting light, lost energy and contracted towards the center of each cloud. Eventually 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 the first heavy elements into space. After several billion years, these clouds with masses of millions of solar masses were grouped under the influence of gravity into the first galaxies.

The radiation from the very first hydrogen clouds, highly redshifted due to expansion, could be detected by huge arrays of radio antennas with a total receiving area of ​​about a square kilometer. When these radio telescopes are built, it will be known how the first generation of stars and galaxies ionized hydrogen and thereby ended the dark era (see: Loeb A. Dark Ages of the Universe // VMN, No. 3, 2007).

Faint glow of a hot start

Behind the dark era, the reflection of the hot Big Bang at redshift 1100 is noticeable. This initially visible (red-orange) radiation, due to the redshift, became not even infrared, but microwaves. Looking back into that era, all we see is 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 for 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 to a temperature of about 3000 K, nuclei and electrons began to combine into atoms. Photons stopped being scattered by 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 varied slightly - by about 0.001%, indicating a slight heterogeneity in the distribution of matter. The degree of primary heterogeneity turned out to be sufficient for small densities 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. Careful study of these irregularities has taught us a lot about the Universe.

COSMIC MICROWAVE BACKGROUND RADIATION is an image of the Universe in its infancy of 380 thousand years. Subtle variations in the intensity of this radiation (color-coded) serve as a cosmic Rosetta Stone, providing clues to the mysteries of the Universe - its age, density, composition and geometry..

HUBBLE'S ULTRA-DEEP FIELD, the most sensitive image of space ever captured, captures more than 1,000 galaxies in the early stages of their formation.

Moving from this point back to the beginning of the evolution of the Universe, we will see how the primordial plasma becomes increasingly hotter and denser. Until the age of about 100 thousand years, the radiation energy density was higher than that of the substance, which kept the substance from fragmentation. And at that moment, the gravitational crowding of all structures now observed in the Universe 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. Nuclei arose when the Universe was a few seconds old and the temperature and density became suitable for nuclear reactions. In this Big Bang nucleosynthesis, only light chemical elements were born: a lot of helium (about 25% by mass of all atoms in the Universe) and some 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 depths of stars and during their explosions.

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

Nucleosynthesis theory accurately predicts the abundances of elements and isotopes measured in the oldest objects in the Universe—the oldest stars and high-redshift gas clouds. Deuterium abundance, which is very sensitive to the average atomic density in the Universe, plays a special role: its measured value shows that ordinary matter accounts for (4.5 ± 0.1)% of the total energy density. The rest is dark matter and dark energy. This agrees exactly with the composition data obtained from background radiation analysis. This consistency is a huge achievement. After all, these are two completely different measurements: the first is based on nuclear physics and refers to the Universe at the age of 1 s, and the second is based 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 cosmic evolution, but for all modern physics.

Answers in quark soup

Before 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 “quark soup” really existed, since the physical conditions of that era are now being reproduced in experiments at particle accelerators (see: Riorden M., Seits U. First microseconds // VMN, No. 8, 2006).

Cosmologists hope to study that era not with the help of large and sharp telescopes, but by relying on deep ideas from 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 application 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 larger Universe. We may soon have answers to three key questions: what is the nature of dark matter, what causes the asymmetry between matter and antimatter, and how lumpy quark soup came to be.

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 beyond 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 other than gravity. Attempts to describe with a single theory all the forces and particles observed in nature lead to the prediction of stable or long-lived particles that dark matter could consist of. These particles may be a relic of the quark soup era and interact very weakly with atoms. One candidate is the neutralino, the lightest of a recently predicted class of particles that are massive replicas of known particles. The neutralino must have a mass from 100 to 1000 times the mass of a proton, 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 ultra-sensitive detectors underground, and also launch them on balloons and satellites.

The second candidate is the axion, an ultra-light 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 detect an axion rely on the fact that in a very strong magnetic field it can turn into a photon. Both the neutralino and the 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 group into galaxies.

Perhaps another secret lies in the era of the primordial quark soup: why the Universe now contains only matter and almost no antimatter. Physicists believe that at first the Universe had an equal amount of them, but at some point a small excess of matter arose - about one extra quark for every billion antiquarks. Thanks to this imbalance, enough quarks were preserved during the annihilation of quarks with antiquarks during the expansion and cooling of the Universe. More than 40 years ago, experiments at accelerators showed that the laws of physics were slightly in favor of matter; It was precisely this small preference in the process of particle interaction at a very early stage that led to the birth of an excess of quarks.

The quark soup itself probably arose very early - about $10^(-34)$ s after the Big Bang, in a burst of cosmic expansion known as inflation. The reason for this burst was the energy of a new field, reminiscent of an electromagnetic field and called inflaton. It is inflation that must explain such fundamental properties of space as its overall homogeneity and small density fluctuations that gave rise to galaxies and other structures in the Universe. When the inflaton decayed, 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: quantum fluctuations of the inflaton, which existed at the subatomic level, grew to astrophysical proportions through rapid expansion and became the seeds for all the structures observed today. In other words, the pattern of microwave background radiation in the sky is a giant image of the subatomic world. The observed properties of this radiation are consistent with the theoretical prediction, proving that inflation, or something similar to it, actually occurred very early in the history of the Universe.

Birth of the Universe

As cosmologists try to push even further and understand the very beginning of the universe, their judgment becomes less confident. 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 advance 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 perhaps the existence of other universes in this superspace. What we call the Big Bang could have been the collision of our Universe with another (see: Veneziano G. The Myth of the Beginning of Time // VMN, No. 8, 2004). Combining string theory with inflation theory leads to perhaps the grandest idea yet - the idea of ​​a multiverse, consisting of an infinite number of disconnected parts, each with its own physical laws. (see: Busso R., Polchinski J. Landscape of string theory // VMN, No. 12, 2004).

The idea of ​​a multiple universe is still developing and addresses two major theoretical problems. Firstly, 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 “inflated” areas. They are so large that they cannot communicate with each other and therefore do not influence 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 the laws of physics are what they are? (Einstein's question, "Did God have a choice?" applied to such laws.) The multiple universe makes the question of what came before the Big Bang meaningless, since there were an infinite number of big bangs, each with its own burst of inflation. Einstein's question also makes no sense: 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 have mixed feelings about the idea of ​​a multiple universe. If there really is no connection between the individual subuniverses, then we will not be able to verify 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 only a small addition to our awareness of our place in the cosmos.

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 causing the acceleration of cosmic expansion. Dark energy took control of matter several billion years ago. Before this, expansion was slowed down by the gravitational pull of matter, and gravity was capable of creating structures - from galaxies to superclusters. Nowadays, due to the influence of dark energy, structures larger than superclusters cannot form. And if dark energy had won even earlier - say, when the age of the Universe was only 100 million years - 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 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 quantum energy density do not agree with observational requirements; in fact, they exceed them by many orders of magnitude. Another possibility: the cosmic acceleration may be driven not by a new form of energy, but by something that mimics that energy, say, the fallacy of general relativity or the influence of invisible spatial dimensions (see: Cross L., Turner M. Space mystery // VMN, No. 12, 2004).

If the Universe continues to accelerate at its current rate, then in 30 billion years all signs of the Big Bang will disappear (see: Cross L., Scherrer R. Will the end of cosmology come? // VMN, No. 6, 2008). All but a few nearby galaxies will experience such a large redshift that they will become invisible. The temperature of the cosmic background radiation will drop below the sensitivity of the instruments. The Universe will look like what astronomers imagined 100 years ago, before their instruments became powerful enough to see the Universe we know today.

Modern cosmology essentially degrades 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 emergence of fluctuations that seeded galaxies, and the filling of space with dark matter particles that provided the gravitational infrastructure that allowed galaxies to form before dark energy took over and expansion began to accelerate (inset above). At the same time, cosmology is arrogant in nature. The idea that we can understand anything in such a vast ocean of space and time as our Universe seems absurd at first glance. This strange mixture of modesty and self-confidence has allowed us to make very good progress over the past century in understanding the structure of the modern Universe and its evolution. I am optimistic about further progress in the coming years and am quite confident that we are living in a golden age of cosmology.

If there was even more dark energy in the Universe, it would remain almost formless (left), without the large structures 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 Energy 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 SB RAS, 2005.

Michael S. Turner pioneered the integration of particle physics, astrophysics, and cosmology and led the National Academy's efforts in this new field of research early in the decade. He is a professor at the Kavli Foundation Institute for Cosmological Physics at the University of Chicago. From 2003 to 2006, he served as director of the National Science Foundation's Division of Physical and Mathematical Sciences. His awards include 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.

Based on knowledge of the current state of the Universe, scientists theorize that everything must have started from a single point with infinite density and finite time, which began to expand. After the initial expansion, the theory goes, the universe went through a cooling phase that allowed the emergence of subatomic particles and later simple atoms. Giant clouds of these ancient elements later, thanks to gravity, began to form stars and galaxies.

All this, according to scientists, began about 13.8 billion years ago, and therefore this starting point is considered the age of the Universe. By exploring various theoretical principles, conducting experiments involving particle accelerators and high-energy states, and conducting astronomical studies of the far reaches of the Universe, scientists have deduced and proposed a chronology of events that began with the Big Bang and led the Universe ultimately to the state of cosmic evolution that is taking place now.

Scientists believe that the earliest periods of the origin of the Universe - lasting from 10 -43 to 10 -11 seconds after the Big Bang - are still the subject of controversy and discussion. If we consider that the laws of physics that we now know could not exist at that time, then it is very difficult to understand how the processes in this early Universe were regulated. In addition, experiments using the possible types of energies that could be present at that time have not yet been carried out. Be that as it may, many theories about the origin of the universe ultimately agree that at some point in time there was a starting point from which everything began.

Age of Singularity

Also known as the Planck epoch (or Planck era), it is taken to be the earliest known period in the evolution of the Universe. At this time, all matter was contained in a single point of infinite density and temperature. During this period, scientists believe, the quantum effects of gravitational interactions dominated the physical ones, and no physical force was equal in strength to gravity.

The Planck era supposedly lasted from 0 to 10 -43 seconds and is so named because its duration can only be measured by Planck time. Due to the extreme temperatures and infinite density of matter, the state of the Universe during this period of time was extremely unstable. This was followed by periods of expansion and cooling that gave rise to the fundamental forces of physics.

Approximately in the period from 10 -43 to 10 -36 seconds, a process of collision of transition temperature states took place in the Universe. It is believed that it was at this point that the fundamental forces that govern the current Universe began to separate from each other. The first step of this separation was the emergence of gravitational forces, strong and weak nuclear interactions and electromagnetism.

During the period from about 10 -36 to 10 -32 seconds after the Big Bang, the temperature of the Universe became low enough (1028 K) that it led to the separation of electromagnetic forces (the strong force) and the weak nuclear force (the weak force).

The Age of Inflation

With the advent of the first fundamental forces in the Universe, the era of inflation began, which lasted from 10 -32 seconds in Planck time to an unknown point in time. Most cosmological models suggest that the Universe during this period was uniformly filled with high-density energy, and incredibly high temperatures and pressures led to its rapid expansion and cooling.

This began at 10 -37 seconds, when the transition phase that caused the separation of forces was followed by the expansion of the Universe in geometric progression. During the same period of time, the Universe was in a state of baryogenesis, when the temperature was so high that the random movement of particles in space occurred at near-light speed.

At this time, pairs of particles - antiparticles are formed and immediately colliding and destroyed, which is believed to have led to the dominance of matter over antimatter in the modern Universe. After inflation stopped, the Universe consisted of quark-gluon plasma and other elementary particles. From that moment on, the Universe began to cool down, matter began to form and combine.

Cooling era

As the density and temperature inside the Universe decreased, the energy in each particle began to decrease. This transitional state lasted until the fundamental forces and elementary particles arrived at their present form. Since the energy of the particles has dropped to values ​​​​that can be achieved today in experiments, the actual possible existence of this time period is much less controversial among scientists.

For example, scientists believe that at 10 -11 seconds after the Big Bang, the particle energy decreased significantly. At about 10 -6 seconds, quarks and gluons began to form baryons - protons and neutrons. Quarks began to predominate over antiquarks, which in turn led to the predominance of baryons over antibaryons.

Since the temperature was no longer high enough to create new proton-antiproton pairs (or neutron-antineutron pairs), massive destruction of these particles ensued, resulting in only 1/1010 of the original protons and neutrons remaining and their antiparticles completely disappearing. A similar process occurred about 1 second after the Big Bang. Only electrons and positrons became the “victims” this time. After the mass destruction, the remaining protons, neutrons and electrons ceased their random motion, and the energy density of the Universe was filled with photons and, to a lesser extent, neutrinos.

During the first minutes of the expansion of the Universe, a period of nucleosynthesis (synthesis of chemical elements) began. With the temperature dropping to 1 billion kelvins and the energy density decreasing to values ​​roughly equivalent to that of air, neutrons and protons began to mix and form the first stable isotope of hydrogen (deuterium), as well as helium atoms. However, most of the protons in the Universe remained as the disconnected nuclei of hydrogen atoms.

After about 379,000 years, the electrons combined with these hydrogen nuclei to form atoms (again predominantly hydrogen), while the radiation separated from matter and continued to expand virtually unimpeded through space. This radiation is called cosmic microwave background radiation, and it is the oldest source of light in the Universe.

With expansion, the CMB gradually lost its density and energy, and at the moment its temperature is 2.7260 ± 0.0013 K (-270.424 °C), and the energy density is 0.25 eV (or 4.005 × 10 -14 J/m³; 400–500 photons/cm³). The CMB extends in all directions and over a distance of about 13.8 billion light-years, but an estimate of its actual spread is about 46 billion light-years from the center of the Universe.

The Age of Structure (Hierarchical Age)

Over the next few billion years, denser regions of matter, almost evenly distributed in the Universe, began to attract each other. As a result of this, they became even denser and began to form clouds of gas, stars, galaxies and other astronomical structures that we can observe today. This period is called the hierarchical era. At this time, the Universe that we see now began to take its form. Matter began to unite into structures of various sizes - stars, planets, galaxies, galaxy clusters, as well as galactic superclusters, separated by intergalactic bridges containing only a few galaxies.

The details of this process can be described according to the idea of ​​the amount and type of matter distributed in the Universe, which is represented as cold, warm, hot dark matter and baryonic matter. However, the current standard cosmological model of the Big Bang is the Lambda-CDM model, according to which dark matter particles move slower than the speed of light. It was chosen because it solves all the contradictions that appeared in other cosmological models.

According to this model, cold dark matter accounts for about 23 percent of all matter/energy in the Universe. The proportion of baryonic matter is about 4.6 percent. Lambda-CDM refers to the so-called cosmological constant: a theory proposed by Albert Einstein that characterizes the properties of the vacuum and shows the balance relationship between mass and energy as a constant static quantity. In this case, it is associated with dark energy, which serves as an accelerator of the expansion of the Universe and keeps giant cosmological structures largely homogeneous.

Long-term predictions for the future of the Universe

Hypotheses that the evolution of the Universe has a starting point naturally lead scientists to questions about the possible end point of this process. If the Universe began its history from a small point with infinite density, which suddenly began to expand, does this not mean that it will also expand infinitely? Or will one day its expansive force run out and the reverse process of compression begin, the end result of which will be the same infinitely dense point?

Answering these questions has been the main goal of cosmologists from the very beginning of the debate about which cosmological model of the Universe is correct. With the acceptance of the Big Bang theory, but largely thanks to the observation of dark energy in the 1990s, scientists have come to agree on the two most likely scenarios for the evolution of the Universe.

According to the first, called the “big crunch,” the Universe will reach its maximum size and begin to collapse. This scenario will be possible only if the mass density of the Universe becomes greater than the critical density itself. In other words, if the density of matter reaches a certain value or becomes higher than this value (1-3x10 -26 kg of matter per m³), ​​the Universe will begin to contract.

The Big Bang - like this

An alternative is another scenario, which states that if the density in the Universe is equal to or lower than the critical density value, then its expansion will slow down, but will never stop completely. According to this hypothesis, called the “heat death of the Universe,” expansion will continue until star formation stops consuming interstellar gas inside each of the surrounding galaxies. That is, the transfer of energy and matter from one object to another will completely stop. All existing stars in this case will burn out and turn into white dwarfs, neutron stars and black holes.

Gradually, black holes will collide with other black holes, leading to the formation of larger and larger ones. The average temperature of the Universe will approach absolute zero. The black holes will eventually "evaporate", releasing their last Hawking radiation. Eventually, thermodynamic entropy in the Universe will reach its maximum. Heat death will occur.

Modern observations that take into account the presence of dark energy and its influence on the expansion of space have led scientists to conclude that over time, more and more of the universe will pass beyond our event horizon and become invisible to us. The final and logical result of this is not yet known to scientists, but “heat death” may well be the end point of such events.

There are other hypotheses regarding the distribution of dark energy, or more precisely, its possible types (for example, phantom energy). According to them, galaxy clusters, stars, planets, atoms, atomic nuclei and matter itself will be torn apart as a result of its endless expansion. This evolutionary scenario is called the “big gap.” The cause of the death of the Universe according to this scenario is the expansion itself.

History of the Big Bang Theory

The earliest mention of the Big Bang dates back to the early 20th century and is associated with observations of space. In 1912, American astronomer Vesto Slipher made a series of observations of spiral galaxies (which were originally thought to be nebulae) and measured their Doppler redshift. In almost all cases, observations have shown that spiral galaxies are moving away from our Milky Way.

In 1922, the outstanding Russian mathematician and cosmologist Alexander Friedman derived the so-called Friedmann equations from Einstein’s equations for general relativity. Despite Einstein's promotion of a theory in favor of a cosmological constant, Friedman's work showed that the Universe was rather in a state of expansion.

In 1924, Edwin Hubble's measurements of the distance to a nearby spiral nebula showed that these systems were in fact truly different galaxies. At the same time, Hubble began developing a series of distance subtraction metrics using the 2.5-meter Hooker Telescope at Mount Wilson Observatory. By 1929, Hubble had discovered a relationship between the distance and the rate at which galaxies recede, which later became Hubble's law.

In 1927, Belgian mathematician, physicist and Catholic priest Georges Lemaitre independently arrived at the same results as Friedmann's equations and was the first to formulate the relationship between the distance and speed of galaxies, offering the first estimate of the coefficient of this relationship. Lemaitre believed that at some time in the past, the entire mass of the Universe was concentrated in one point (an atom).

These discoveries and assumptions caused much debate among physicists in the 20s and 30s, most of whom believed that the Universe was in a stationary state. According to the model that was established at that time, new matter is created along with the infinite expansion of the Universe, distributed evenly and equally in density throughout its entire extent. Among the scientists who supported it, the Big Bang idea seemed more theological than scientific. Lemaître has been criticized for being biased on the basis of religious prejudice.

It should be noted that other theories existed at the same time. For example, the Milne model of the Universe and the cyclic model. Both were based on the postulates of Einstein’s general theory of relativity and subsequently received the support of the scientist himself. According to these models, the Universe exists in an endless stream of repeating cycles of expansion and collapse.

After World War II, a heated debate erupted between supporters of the steady-state model of the Universe (which was actually described by astronomer and physicist Fred Hoyle) and supporters of the Big Bang theory, which was rapidly gaining popularity among the scientific community. Ironically, it was Hoyle who coined the phrase “,” which later became the name of the new theory. This happened in March 1949 on British BBC radio.

Eventually, further scientific research and observations increasingly favored the Big Bang theory and increasingly cast doubt on the model of a stationary Universe. The discovery and confirmation of the CMB in 1965 finally cemented the Big Bang as the best theory for the origin and evolution of the Universe. From the late 1960s through the 1990s, astronomers and cosmologists conducted even more research into the Big Bang and found solutions to many of the theoretical problems that stood in the way of the theory.

These solutions include, for example, the work of Stephen Hawking and other physicists who proved that the singularity was the undeniable initial state of general relativity and the cosmological model of the Big Bang. In 1981, physicist Alan Guth developed a theory describing a period of rapid cosmic expansion (the era of inflation), which resolved many previously unresolved theoretical questions and problems.

The 1990s saw increased interest in dark energy, which was seen as the key to solving many outstanding questions in cosmology. In addition to the desire to find an answer to the question of why the Universe is losing its mass along with the dark mother (a hypothesis proposed back in 1932 by Jan Oort), it was also necessary to find an explanation for why the Universe is still accelerating.

Further progress in the study is due to the creation of more advanced telescopes, satellites and computer models, which have allowed astronomers and cosmologists to look further into the Universe and better understand its true age. The development of space telescopes such as the Cosmic Background Explorer (or COBE), the Hubble Space Telescope, the Wilkinson Microwave Anisotropy Probe (WMAP) and the Planck Space Observatory have also made invaluable contributions to the study.

Today, cosmologists can measure various parameters and characteristics of the Big Bang theory model with fairly high accuracy, not to mention more accurate calculations of the age of the cosmos around us. But it all started with the usual observation of massive space objects located many light years away from us and slowly continuing to move away from us. And even though we have no idea how this will all end, it won't take very long by cosmological standards to find out.