Big bang evolution of the universe our galaxy. The emergence of the Big Bang theory

In the scientific world, it is generally accepted that the Universe originated as a result of the Big Bang. This theory is based on the fact that energy and matter (the foundations of all things) were previously in a state of singularity. It, in turn, is characterized by the infinity of temperature, density and pressure. The singularity state itself defies all the laws of physics known to the modern world. Scientists believe that the Universe arose from a microscopic particle, which, due to unknown reasons, came into an unstable state in the distant past and exploded.

The term "Big Bang" began to be used since 1949 after the publication of the works of the scientist F. Hoyle in popular science publications. Today, the theory of the “dynamic evolving model” has been developed so well that physicists can describe the processes occurring in the Universe as early as 10 seconds after the explosion of a microscopic particle that laid the foundation for everything.

There are several proofs of the theory. One of the main ones is the relic radiation, which permeates the entire Universe. It could have arisen, according to modern scientists, only as a result of the Big Bang, due to the interaction of microscopic particles. It is the relic radiation that makes it possible to learn about those times when the Universe looked like a blazing space, and there were no stars, planets and the galaxy itself. The second proof of the birth of everything that exists from the Big Bang is the cosmological redshift, which consists in a decrease in the frequency of radiation. This confirms the removal of stars, galaxies from the Milky Way in particular and from each other in general. That is, it indicates that the Universe expanded earlier and continues to do so until now.

A Brief History of the Universe

• 10 -45 - 10 -37 sec- inflationary expansion


• 10 -6 sec- the emergence of quarks and electrons


• 10 -5 sec- the formation of protons and neutrons


• 10 -4 sec - 3 min- the emergence of nuclei of deuterium, helium and lithium


• 400 thousand years- formation of atoms


• 15 million years- continued expansion of the gas cloud


• 1 billion years- the birth of the first stars and galaxies


• 10 - 15 billion years- the emergence of planets and intelligent life


• 10 14 billion years- termination of the process of birth of stars


• 10 37 billion years- depletion of the energy of all stars


• 10 40 billion years- evaporation of black holes and the birth of elementary particles


• 10 100 billion years- completion of the evaporation of all black holes

The Big Bang theory has become a real breakthrough in science. It allowed scientists to answer many questions regarding the birth of the universe. But at the same time, this theory gave rise to new mysteries. Chief among them is the cause of the Big Bang itself. The second question to which modern science has no answer is how space and time appeared. According to some researchers, they were born together with matter, energy. That is, they are the result of the Big Bang. But then it turns out that time and space must have some kind of beginning. That is, a certain entity, permanently existing and not dependent on their indicators, could well initiate the processes of instability in a microscopic particle that gave rise to the Universe.

The more research is done in this direction, the more questions arise for astrophysicists. The answers to them await mankind in the future.

« For me, life is too short to worry about things beyond my control and maybe even impossible. Here they ask: “What if the Earth is swallowed up by a black hole, or there is a distortion of space-time - is this a reason for excitement?” My answer is no, because we will only know about it when it reaches our ... our place in space-time. We get kicks when nature decides it's time: whether it's the speed of sound, the speed of light, the speed of electrical impulses, we will always be victims of a time delay between the information around us and our ability to receive it.»

Neil deGrasse Tyson

Time is an amazing thing. It gives us the past, present and future. Because of time, everything that surrounds us has an age. For example, the age of the Earth is approximately 4.5 billion years. Approximately the same number of years ago, the closest star to us, the Sun, also lit up. If this figure seems mind-boggling to you, do not forget that long before the formation of our native solar system, the galaxy in which we live - the Milky Way appeared. According to scientists' latest estimates, the age of the Milky Way is 13.6 billion years. But we know for sure that galaxies also have a past, and space is simply huge, so we need to look even further. And this reflection inevitably leads us to the moment when it all began - the Big Bang.

Einstein and the Universe

The perception of the surrounding world by people has always been ambiguous. Someone still does not believe in the existence of a huge Universe around us, someone considers the Earth to be flat. Before the scientific breakthrough in the 20th century, there were only a couple of versions of the origin of the world. Adherents of religious views believed in divine intervention and the creation of a higher mind, those who disagreed were sometimes burned. There was another side that believed that the world around us, as well as the Universe, is infinite.

For many people, everything changed when Albert Einstein gave a talk in 1917, presenting to the general public the work of his life - the General Theory of Relativity. The genius of the 20th century connected space-time with the matter of space with the help of the equations he derived. As a result, it turned out that the Universe is finite, unchanged in size and has the shape of a regular cylinder.

At the dawn of a technical breakthrough, no one could refute Einstein's words, because his theory was too complicated even for the greatest minds of the early 20th century. Since there were no other options, the model of a cylindrical stationary universe was accepted by the scientific community as a generally accepted model of our world. However, she could live only a few years. After the physicists were able to recover from the scientific works of Einstein and began to sort them out on the shelves, in parallel with this, adjustments began to be made to the theory of relativity and the specific calculations of the German scientist.

In 1922, the Russian mathematician Alexander Fridman suddenly published an article in the journal Izvestiya Fiziki, in which he states that Einstein was wrong and our Universe is not stationary. Friedman explains that the statements of the German scientist regarding the invariability of the radius of curvature of space are delusions, in fact, the radius changes with respect to time. Accordingly, the universe must expand.

Moreover, here Friedman gave his assumptions about how exactly the Universe can expand. There were three models in total: a pulsating Universe (the assumption that the Universe expands and contracts with a certain periodicity in time); the expanding Universe from the mass and the third model - the expansion from the point. Since at that time there were no other models, with the exception of divine intervention, physicists quickly took note of all three Friedman models and began to develop them in their own direction.

The work of the Russian mathematician slightly stung Einstein, and in the same year he published an article in which he expressed his comments on the work of Friedman. In it, a German physicist tries to prove the correctness of his calculations. It turned out rather unconvincingly, and when the pain from the blow to self-esteem subsided a little, Einstein published another note in the journal Izvestiya Fiziki, in which he said:

« In a previous note, I criticized the above work. However, my criticism, as I saw from Fridman's letter communicated to me by Mr. Krutkov, was based on an error in calculations. I think Friedman's results are correct and shed new light.».

Scientists had to admit that all three Friedman models of the appearance and existence of our Universe are absolutely logical and have the right to life. All three are explained by understandable mathematical calculations and leave no questions. Except for one thing: why would the Universe begin to expand?

The theory that changed the world

The statements of Einstein and Friedman led the scientific community to seriously question the origin of the universe. Thanks to the general theory of relativity, there was a chance to shed light on our past, and physicists did not fail to take advantage of this. One of the scientists who tried to present a model of our world was the astrophysicist Georges Lemaitre from Belgium. It is noteworthy that Lemaitre was a Catholic priest, but at the same time he was engaged in mathematics and physics, which is real nonsense for our time.

Georges Lemaitre became interested in Einstein's equations, and with their help he was able to calculate that our Universe appeared as a result of the decay of some kind of superparticle, which was out of space and time before the fission began, which can actually be considered an explosion. At the same time, physicists note that Lemaitre was the first to shed light on the birth of the Universe.

The theory of the exploded superatom suited not only scientists, but also the clergy, who were very dissatisfied with modern scientific discoveries, for which they had to come up with new interpretations of the Bible. The Big Bang did not come into significant conflict with religion, perhaps this was influenced by the upbringing of Lemaitre himself, who devoted his life not only to science, but also to the service of God.

On November 22, 1951, Pope Pius XII made a statement that the Big Bang Theory does not conflict with the Bible and Catholic dogma about the origin of the world. Orthodox clergy also said they were positive about this theory. This theory was also relatively neutrally accepted by adherents of other religions, some of them even said that there were references to the Big Bang in their scriptures.

However, despite the fact that the Big Bang Theory is currently the generally accepted cosmological model, it has led many scientists into a dead end. On the one hand, the explosion of a superparticle fits perfectly into the logic of modern physics, but on the other hand, as a result of such an explosion, mainly only heavy metals, in particular iron, could be formed. But, as it turned out, the Universe consists mainly of ultralight gases - hydrogen and helium. Something did not fit, so physicists continued to work on the theory of the origin of the world.

Initially, the term "Big Bang" did not exist. Lemaitre and other physicists offered only the boring name "dynamical evolutionary model", which caused students to yawn. Only in 1949, at one of his lectures, did the British astronomer and cosmologist Freud Hoyle say:

“This theory is based on the assumption that the universe arose in the process of a single powerful explosion and therefore exists only for a finite time ... This idea of ​​the Big Bang seems to me completely unsatisfactory”.

Since then, this term has become widely used in scientific circles and the general public's idea of ​​\u200b\u200bthe structure of the Universe.

Where did hydrogen and helium come from?

The presence of light elements has baffled physicists, and many Big Bang Theorists set out to find their source. For many years they were not able to achieve much success, until in 1948 the brilliant scientist Georgy Gamov from Leningrad was finally able to identify this source. Gamow was one of Friedman's students, so he gladly took up the development of the theory of his teacher.

Gamow tried to imagine the life of the Universe in the opposite direction, and rewound time until the moment when it had just begun to expand. By that time, as is known, humanity had already discovered the principles of thermonuclear fusion, so the Friedmann-Lemaitre theory gained the right to life. When the universe was very small, it was very hot, according to the laws of physics.

According to Gamow, just a second after the Big Bang, the space of the new Universe was filled with elementary particles that began to interact with each other. As a result of this, helium thermonuclear fusion began, which Ralph Asher Alfer, a mathematician from Odessa, was able to calculate for Gamow. According to Alfer's calculations, already five minutes after the Big Bang, the Universe was filled with helium so much that even staunch opponents of the Big Bang Theory will have to come to terms and accept this model as the main one in cosmology. With his research, Gamow not only opened up new ways of studying the Universe, but also resurrected Lemaitre's theory.

Despite the stereotypes about scientists, they cannot be denied romanticism. Gamow published his research on the theory of the Superhot Universe at the time of the Big Bang in 1948 in his work The Origin of the Chemical Elements. As fellow assistants, he indicated not only Ralph Asher Alfer, but also Hans Bethe, an American astrophysicist and future Nobel Prize winner. On the cover of the book it turned out: Alfer, Bethe, Gamow. Doesn't it remind you of anything?

However, despite the fact that Lemaitre's works received a second life, physicists still could not answer the most exciting question: what happened before the Big Bang?

Attempts to resurrect Einstein's stationary Universe

Not all scientists agreed with the Friedmann-Lemaitre theory, but despite this, they had to teach the generally accepted cosmological model at universities. For example, astronomer Fred Hoyle, who himself coined the term "Big Bang", actually believed that there was no explosion, and devoted his life to trying to prove it.
Hoyle has become one of those scientists who in our time offer an alternative view of the modern world. Most physicists are rather cool about the statements of such people, but this does not bother them at all.

To shame Gamow and his justification of the Big Bang Theory, Hoyle, together with like-minded people, decided to develop their own model of the origin of the Universe. As a basis, they took Einstein's proposals that the Universe is stationary, and made some adjustments that offer alternative reasons for the expansion of the Universe.

If adherents of the Lemaitre-Friedmann theory believed that the Universe arose from one single superdense point with an infinitely small radius, then Hoyle suggested that matter is constantly formed from points that are between galaxies moving away from each other. In the first case, the whole Universe was formed from one particle, with its infinite number of stars and galaxies. In another case, one point gives as much matter as is enough to produce just one galaxy.

The inconsistency of Hoyle's theory is that he was never able to explain where the very substance comes from, which continues to create galaxies in which there are hundreds of billions of stars. In fact, Fred Hoyle suggested that everyone believe that the structure of the universe appears out of nowhere. Despite the fact that many physicists tried to find a solution to Hoyle's theory, no one managed to do this, and after a couple of decades this proposal lost its relevance.

Questions without answers

In fact, the Big Bang Theory also does not give us answers to many questions. For example, in the mind of an ordinary person, the fact that all the matter around us was once compressed into a single point of singularity, which is much smaller than an atom, cannot fit in. And how did it happen that this superparticle heated up to such an extent that the explosion reaction started.

Until the middle of the 20th century, the theory of the expanding universe was never confirmed experimentally, therefore it was not widely used in educational institutions. Everything changed in 1964, when two American astrophysicists - Arno Penzias and Robert Wilson - did not decide to study the radio signals of the starry sky.

Scanning the radiation of celestial bodies, namely Cassiopeia A (one of the most powerful sources of radio emission in the starry sky), scientists noticed some kind of extraneous noise that constantly interfered with recording accurate radiation data. Wherever they pointed their antenna, no matter what time of day they began their research, this characteristic and constant noise always pursued them. Angry to a certain extent, Penzias and Wilson decided to study the source of this noise and unexpectedly made a discovery that changed the world. They discovered the relic radiation, which is an echo of that same Big Bang.

Our universe cools much more slowly than a cup of hot tea, and the CMB indicates that the matter around us was once very hot and is now cooling as the universe expands. Thus, all theories related to the cold Universe were left out, and the Big Bang Theory was finally adopted.

In his writings, Georgy Gamow suggested that it would be possible to detect photons in space that have existed since the Big Bang, only more advanced technical equipment is needed. Relic radiation confirmed all his assumptions about the existence of the universe. Also, with its help, it was possible to establish that the age of our Universe is approximately 14 billion years.

As always, with the practical proof of any theory, many alternative opinions immediately arise. Some physicists scoffed at the discovery of the CMB as evidence of the Big Bang. Despite the fact that Penzias and Wilson won the Nobel Prize for their historic discovery, many disagreed with their research.

The main arguments in favor of the inconsistency of the expansion of the Universe were discrepancies and logical errors. For example, the explosion uniformly accelerated all the galaxies in space, but instead of moving away from us, the Andromeda galaxy is slowly but surely approaching the Milky Way. Scientists suggest that these two galaxies will collide with each other in just some 4 billion years. Unfortunately, humanity is still too young to answer this and other questions.

Theory of equilibrium

In our time, physicists offer various models for the existence of the universe. Many of them do not withstand even simple criticism, while others receive the right to life.

At the end of the 20th century, an astrophysicist from America, Edward Tryon, together with his colleague from Australia, Warren Kerry, proposed a fundamentally new model of the Universe, and they did it independently of each other. Scientists based their research on the assumption that everything in the universe is balanced. Mass destroys energy, and vice versa. This principle became known as the principle of the Zero Universe. Within this universe, new matter emerges at singular points between galaxies, where the attraction and repulsion of matter is balanced.

The theory of the Zero Universe was not smashed to smithereens because after some time scientists were able to discover the existence of dark matter - a mysterious substance that makes up almost 27% of our Universe. Another 68.3% of the universe is more mysterious and mysterious dark energy.

It is thanks to the gravitational effects of dark energy that the acceleration of the expansion of the Universe is attributed. By the way, the presence of dark energy in space was predicted by Einstein himself, who saw that something did not converge in his equations, the Universe could not be made stationary. Therefore, he introduced a cosmological constant into the equations - the Lambda term, for which he later repeatedly blamed and hated himself.

It so happened that the space in the Universe, empty in theory, is nevertheless filled with a certain special field, which drives the Einstein model. In a sober mind and according to the logic of those times, the existence of such a field was simply impossible, but in fact the German physicist simply did not know how to describe dark energy.

***
Perhaps we will never know how and from what our universe arose. It will be even more difficult to establish what was before its existence. People tend to be afraid of what they cannot explain, so it is possible that until the end of time humanity will also believe in the divine influence on the creation of the world around us.

The answer to the question "What is the Big Bang?" can be obtained in the course of a long discussion, since it takes a lot of time. I will try to explain this theory briefly and to the point. So, the "Big Bang" theory postulates that our universe suddenly appeared approximately 13.7 billion years ago (everything appeared from nothing). And what happened then still affects how and in what way everything in the universe interacts with each other. Consider the key points of the theory.

What happened before the Big Bang?

The Big Bang theory includes a very interesting concept - the singularity. I bet it makes you wonder: what is a singularity? Astronomers, physicists and other scientists are also asking this question. Singularities are believed to exist in the cores of black holes. A black hole is an area of ​​intense gravitational pressure. This pressure, according to the theory, is so intense that matter is compressed until it has an infinite density. This infinite density is called singularity. Our Universe is supposed to have started as one of these infinitely small, infinitely hot and infinitely dense singularities. However, we have not yet come to the Big Bang itself. The Big Bang is the moment at which this singularity suddenly "exploded" and began to expand and created our Universe.

The Big Bang theory would seem to imply that time and space existed before our universe arose. However, Stephen Hawking, George Ellis and Roger Penrose (et al.) developed a theory in the late 1960s that tried to explain that time and space did not exist before the expansion of the singularity. In other words, neither time nor space existed until the universe existed.

What happened after the Big Bang?

The moment of the Big Bang is the moment of the beginning of time. After the Big Bang, but long before the first second (10 -43 seconds), the cosmos experiences an ultra-rapid inflationary expansion, expanding 1050 times in a fraction of a second.

Then the expansion slows down, but the first second has not yet arrived (only 10 -32 seconds more). At this moment, the Universe is a boiling "broth" (with a temperature of 10 27 °C) of electrons, quarks and other elementary particles.

The rapid cooling of space (up to 10 13 ° C) allows quarks to combine into protons and neutrons. However, the first second has not yet arrived (only 10 -6 seconds more).

At 3 minutes, too hot to combine into atoms, the charged electrons and protons prevent light from being emitted. The Universe is a superhot fog (10 8 °C).

After 300,000 years, the universe cools down to 10,000 °C, electrons with protons and neutrons form atoms, mainly hydrogen and helium.

1 billion years after the Big Bang, when the temperature of the universe reached -200 ° C, hydrogen and helium form giant "clouds" that will later become galaxies. The first stars appear.

12. What caused the Big Bang?

The Paradox of Emergence

Not one of the lectures on cosmology that I have ever read was complete without the question of what caused the Big Bang? Until a few years ago, I did not know the true answer; Today, I believe, he is famous.

Essentially, this question contains two questions in a veiled form. First, we would like to know why the development of the universe began with an explosion and what caused this explosion in the first place. But behind the purely physical problem lies another, deeper problem of a philosophical nature. If the Big Bang marks the beginning of the physical existence of the universe, including the emergence of space and time, then in what sense can we say that what caused this explosion?

From the point of view of physics, the sudden emergence of the universe as a result of a giant explosion seems to some extent paradoxical. Of the four interactions that govern the world, only gravity manifests itself on a cosmic scale, and, as our experience shows, gravity has the character of attraction. However, for the explosion that marked the birth of the universe, apparently, a repulsive force of incredible magnitude was needed, which could tear the cosmos to shreds and cause its expansion, which continues to this day.

This seems strange, because if the universe is dominated by gravitational forces, then it should not expand, but contract. Indeed, gravitational forces of attraction cause physical objects to shrink rather than explode. For example, a very dense star loses its ability to support its own weight and collapses to form a neutron star or black hole. The degree of compression of matter in the very early universe was much higher than that of the densest star; therefore, the question often arises why the primordial cosmos did not collapse into a black hole from the very beginning.

The usual answer to this is that the primary explosion should simply be taken as the initial condition. This answer is clearly unsatisfactory and perplexing. Of course, under the influence of gravity, the rate of cosmic expansion was continuously decreasing from the very beginning, but at the moment of birth, the Universe was expanding infinitely fast. The explosion was not caused by any force - just the development of the universe began with expansion. If the explosion were less strong, gravity would very soon prevent the expansion of matter. As a result, the expansion would be replaced by contraction, which would take on a catastrophic character and turn the Universe into something similar to a black hole. But in reality, the explosion turned out to be “big enough” that it made it possible for the Universe, having overcome its own gravity, either to continue to expand forever due to the force of the primary explosion, or at least to exist for many billions of years before undergoing compression and disappearing into oblivion.

The problem with this traditional picture is that it does not explain the Big Bang in any way. The fundamental property of the Universe is again simply treated as an initial condition, accepted ad hoc(for this case); in essence, it only states that the Big Bang took place. It still remains unclear why the force of the explosion was just that, and not another. Why wasn't the explosion even more powerful so that the universe is expanding much faster now? One might also ask why the universe is not currently expanding much more slowly, or not contracting at all. Of course, if the explosion did not have sufficient force, the universe would soon collapse and there would be no one to ask such questions. It is unlikely, however, that such reasoning can be taken as an explanation.

Upon closer analysis, it turns out that the paradox of the origin of the universe is actually even more complex than described above. Careful measurements show that the expansion rate of the universe is very close to the critical value at which the universe is able to overcome its own gravity and expand forever. If this speed were a little less - and the collapse of the Universe would occur, and if it were a little more - the cosmic matter would have completely dissipated long ago. It is interesting to find out how exactly the expansion rate of the Universe falls within this very narrow allowable interval between two possible catastrophes. If at the moment of time corresponding to 1 s, when the expansion pattern had already been clearly defined, the expansion velocity would differ from its real value by more than 10^-18 , this would be enough to completely upset the delicate balance. Thus, the force of the explosion of the Universe with almost incredible accuracy corresponds to its gravitational interaction. The big bang, then, was not just some distant explosion - it was an explosion of a very specific force. In the traditional version of the Big Bang theory, one has to accept not only the fact of the explosion itself, but also the fact that the explosion occurred in an extremely whimsical way. In other words, the initial conditions turn out to be extremely specific.

The expansion rate of the universe is just one of several apparent cosmic mysteries. The other is connected with the picture of the expansion of the Universe in space. According to modern observations. The universe, on a large scale, is extremely homogeneous as far as the distribution of matter and energy is concerned. The global structure of the cosmos is almost the same when viewed from Earth and from a distant galaxy. Galaxies are scattered in space with the same average density, and from every point the Universe looks the same in all directions. The primary thermal radiation that fills the Universe falls on the Earth, having the same temperature in all directions with an accuracy of at least 10-4 . This radiation travels through space for billions of light-years on its way to us and bears the imprint of any deviation from homogeneity it encounters.

The large-scale homogeneity of the universe persists as the universe expands. It follows that the expansion occurs uniformly and isotropically with a very high degree of accuracy. This means that the rate of expansion of the universe is not only the same in all directions, but is also constant in different areas. If the Universe expanded faster in one direction than in others, then this would lead to a decrease in the temperature of the background thermal radiation in this direction and would change the picture of the motion of galaxies visible from the Earth. Thus, the evolution of the Universe did not just begin with an explosion of a strictly defined force - the explosion was clearly "organized", i.e. occurred simultaneously, with exactly the same force at all points and in all directions.

It is extremely unlikely that such a simultaneous and coordinated eruption could occur purely spontaneously, and this doubt is reinforced in the traditional Big Bang theory by the fact that different regions of the primordial cosmos are causally unrelated to each other. The fact is that, according to the theory of relativity, no physical effect can propagate faster than light. Consequently, different regions of space can be causally connected with each other only after a certain period of time has passed. For example, 1 s after the explosion, light can travel a distance of no more than one light second, which corresponds to 300,000 km. The regions of the Universe, separated by a large distance, after 1s will not yet influence each other. But by this moment, the region of the Universe we observed already occupied a space of at least 10^14 km in diameter. Therefore, the universe consisted of about 10^27 causally unrelated regions, each of which, nevertheless, expanded at exactly the same rate. Even today, observing thermal cosmic radiation coming from opposite sides of the starry sky, we register exactly the same "fingerprint" prints of regions of the Universe separated by huge distances: these distances turn out to be more than 90 times greater than the distance that light could travel from the moment the thermal radiation was emitted .

How to explain such a remarkable coherence of different regions of space, which, obviously, have never been connected with each other? How did this similar behavior come about? In the traditional answer, there is again a reference to special initial conditions. The exceptional homogeneity of the properties of the primary explosion is regarded simply as a fact: this is how the Universe came into being.

The large-scale homogeneity of the universe is even more puzzling when one considers that the universe is by no means homogeneous on a small scale. The existence of individual galaxies and galaxy clusters indicates a deviation from strict homogeneity, and this deviation, moreover, is everywhere the same in scale and magnitude. Since gravity tends to increase any initial accumulation of matter, the degree of heterogeneity required for the formation of galaxies was much less at the time of the Big Bang than it is now. However, in the initial phase of the Big Bang, a slight inhomogeneity should still be present, otherwise galaxies would never have formed. In the old Big Bang theory, these inhomogeneities were also attributed at an early stage to "initial conditions". Thus, we had to believe that the development of the universe began not from a completely ideal, but from a highly unusual state.

All of the above can be summarized as follows: if the only force in the universe is gravitational attraction, then the Big Bang should be interpreted as "sent down by God", i.e. having no cause, with given initial conditions. In addition, it is characterized by amazing consistency; to come to the existing structure, the universe had to develop properly from the very beginning. This is the paradox of the origin of the universe.

Search for antigravity

The paradox of the origin of the universe has been resolved only in recent years; however, the main idea of ​​the solution can be traced back to distant history, to a time when neither the theory of the expansion of the Universe nor the theory of the Big Bang existed yet. Even Newton understood how difficult the problem is the stability of the universe. How do stars maintain their position in space without support? The universal nature of gravitational attraction should have led to the constriction of stars into clusters close to each other.

To avoid this absurdity, Newton resorted to a very curious reasoning. If the universe were to collapse under its own gravity, each star would "fall" towards the center of the cluster of stars. Suppose, however, that the universe is infinite and that the stars are distributed on average uniformly over infinite space. In this case, there would be no common center at all, towards which all the stars could fall, because in the infinite Universe all regions are identical. Any star would be affected by the gravitational attraction of all its neighbors, but due to the averaging of these influences in various directions, there would be no resultant force tending to move this star to a certain position relative to the entire set of stars.

When, 200 years after Newton, Einstein created a new theory of gravity, he was also puzzled by the problem of how the universe manages to avoid collapse. His first work on cosmology was published before Hubble discovered the expansion of the universe; so Einstein, like Newton, assumed that the universe is static. However, Einstein tried to solve the problem of the stability of the universe in a much more direct way. He believed that in order to prevent the collapse of the universe under the influence of its own gravity, there must be another cosmic force that could resist gravity. This force must be a repulsive rather than an attractive force to offset the gravitational pull. In this sense, such a force could be called "anti-gravitational", although it is more correct to speak of the force of cosmic repulsion. Einstein in this case did not just arbitrarily invent this force. He showed that an additional term can be introduced into his equations of the gravitational field, which leads to the appearance of a force with the desired properties.

Despite the fact that the idea of ​​a repulsive force opposing the force of gravity is quite simple and natural in itself, in reality the properties of such a force turn out to be quite unusual. Of course, no such force has been observed on Earth, and no hint of it has been found for several centuries of the existence of planetary astronomy. Obviously, if the force of cosmic repulsion exists, then it should not have any noticeable effect at small distances, but its magnitude increases significantly on astronomical scales. Such behavior contradicts all previous experience in studying the nature of forces: they are usually intense at small distances and weaken with increasing distance. Thus, the electromagnetic and gravitational interactions continuously decrease according to the inverse square law. Nevertheless, in Einstein's theory, a force with such rather unusual properties naturally appeared.

One should not think of the force of cosmic repulsion introduced by Einstein as the fifth interaction in nature. It's just a bizarre manifestation of gravity itself. It is easy to show that the effects of cosmic repulsion can be attributed to ordinary gravity, if a medium with unusual properties is chosen as the source of the gravitational field. An ordinary material medium (for example, a gas) exerts pressure, while the hypothetical medium discussed here should have negative pressure or tension. In order to more clearly imagine what we are talking about, let us imagine that we managed to fill a vessel with such cosmic substance. Then, unlike ordinary gas, the hypothetical space medium will not put pressure on the walls of the vessel, but will tend to draw them into the vessel.

Thus, we can consider cosmic repulsion as a kind of addition to gravity or as a phenomenon due to ordinary gravity inherent in an invisible gaseous medium that fills all space and has negative pressure. There is no contradiction in the fact that, on the one hand, the negative pressure, as it were, sucks in the walls of the vessel, and, on the other hand, this hypothetical medium repels galaxies, and does not attract them. After all, repulsion is due to the gravity of the medium, and by no means a mechanical action. In any case, mechanical forces are created not by the pressure itself, but by the pressure difference, but it is assumed that the hypothetical medium fills the entire space. It cannot be limited by the walls of the vessel, and an observer located in this environment would not perceive it at all as a tangible substance. The space would look and feel completely empty.

Despite such amazing features of the hypothetical medium, Einstein once said that he had built a satisfactory model of the Universe, in which a balance is maintained between gravitational attraction and the cosmic repulsion discovered by him. With the help of simple calculations, Einstein estimated the magnitude of the cosmic repulsion force needed to balance gravity in the universe. He was able to confirm that the repulsion must be so small within the Solar System (and even on the scale of the Galaxy) that it cannot be detected experimentally. For a while, it seemed that the age-old mystery had been brilliantly solved.

However, then the situation changed for the worse. First of all, the problem of equilibrium stability arose. Einstein's basic idea was based on a strict balance between attractive and repulsive forces. But, as in many other cases of strict balance, subtle details also came to light here. If, for example, Einstein's static universe were to expand a little, then the gravitational attraction (weakening with distance) would decrease somewhat, while the cosmic repulsion force (increasing with distance) would slightly increase. This would lead to an imbalance in favor of repulsive forces, which would cause further unlimited expansion of the Universe under the influence of an all-conquering repulsion. If, on the contrary, Einstein's static universe were to contract slightly, then the gravitational force would increase and the force of cosmic repulsion would decrease, which would lead to an imbalance in favor of the forces of attraction and, as a result, to an ever faster contraction, and ultimately to the collapse that Einstein thought he had avoided. Thus, at the slightest deviation, the strict balance would be upset, and a cosmic catastrophe would be inevitable.

Later, in 1927, Hubble discovered the recession of galaxies (i.e., the expansion of the universe), which made the problem of equilibrium meaningless. It became clear that the universe is not threatened by compression and collapse, since it expands. If Einstein had not been distracted by the search for the force of cosmic repulsion, he would certainly have come to this conclusion theoretically, thus predicting the expansion of the Universe a good ten years before astronomers managed to discover it. Such a prediction would undoubtedly go down in the history of science as one of the most outstanding (such a prediction was made on the basis of the Einstein equation in 1922-1923 by Professor A. A. Fridman of Petrograd University). In the end, Einstein had to ruefully renounce cosmic repulsion, which he later considered "the biggest mistake of his life." However, the story didn't end there.

Einstein came up with cosmic repulsion to solve the nonexistent problem of a static universe. But, as is always the case, a genie out of the bottle cannot be driven back. The idea that the dynamics of the universe, perhaps due to the confrontation between the forces of attraction and repulsion, continued to live. And although astronomical observations did not give any evidence of the existence of cosmic repulsion, they could not prove its absence either - it could simply be too weak to manifest itself.

Einstein's gravitational field equations, although they admit the presence of a repulsive force, do not impose restrictions on its magnitude. Taught by bitter experience, Einstein was right to postulate that the magnitude of this force is strictly equal to zero, thereby completely eliminating repulsion. However, this was by no means necessary. Some scientists found it necessary to keep the repulsion in the equations, although this was no longer necessary from the point of view of the original problem. These scientists believed that, in the absence of proper evidence, there was no reason to believe that the repulsive force was zero.

It was not difficult to trace the consequences of the conservation of the repulsive force in the expanding universe scenario. In the early stages of development, when the Universe is still in a compressed state, repulsion can be neglected. During this phase, gravitational pull slowed the rate of expansion, in much the same way that the Earth's gravity slows down a rocket fired vertically upwards. If we accept without explanation that the evolution of the universe began with a rapid expansion, then gravity should constantly reduce the expansion rate to the value observed at the present time. Over time, as matter dissipates, the gravitational interaction weakens. On the contrary, the cosmic repulsion increases as the galaxies continue to move away from each other. Ultimately, the repulsion will overcome the gravitational attraction and the expansion rate of the Universe will begin to increase again. From this we can conclude that the universe is dominated by cosmic repulsion, and the expansion will continue forever.

Astronomers have shown that this unusual behavior of the universe, when the expansion first slows down and then accelerates again, should be reflected in the observed movement of galaxies. But the most careful astronomical observations failed to reveal any convincing evidence of such behavior, although the opposite assertion is made from time to time.

It is interesting that the Dutch astronomer Willem de Sitter put forward the idea of ​​an expanding universe as early as 1916 - many years before Hubble discovered this phenomenon experimentally. De Sitter argued that if ordinary matter is removed from the universe, then gravitational attraction will disappear, and repulsive forces will reign supreme in space. This will cause the expansion of the universe - at that time it was an innovative idea.

Since the observer is unable to perceive the strange invisible gaseous medium with negative pressure, it will simply appear to him that empty space is expanding. The expansion could be detected by hanging test bodies in various places and observing their distance from each other. The idea of ​​an expansion of empty space was regarded at the time as a kind of curiosity, although, as we shall see, it turned out to be prophetic.

So what conclusion can be drawn from this story? The fact that astronomers do not detect cosmic repulsion cannot yet serve as a logical proof of its absence in nature. It is quite possible that it is simply too weak to be detected by modern instruments. The accuracy of observation is always limited, and therefore only the upper limit of this force can be estimated. Against this one might object that, from an aesthetic point of view, the laws of nature would look simpler in the absence of cosmic repulsion. Such discussions dragged on for many years, without leading to definite results, until suddenly the problem was looked at from a completely new angle, which gave it unexpected relevance.

Inflation: Explaining the Big Bang

In the previous sections, we said that if there is a cosmic repulsion force, then it must be very weak, so weak that it does not have any significant effect on the Big Bang. However, this conclusion is based on the assumption that the magnitude of the repulsion does not change with time. At the time of Einstein, this opinion was shared by all scientists, since cosmic repulsion was introduced into the theory “man-made”. It never occurred to anyone that cosmic repulsion could be called other physical processes that arise as the universe expands. If such a possibility were foreseen, then the cosmology could turn out to be different. In particular, the scenario of the evolution of the Universe is not excluded, assuming that in the extreme conditions of the early stages of evolution, cosmic repulsion prevailed over gravity for some instant, causing the Universe to explode, after which its role practically reduced to zero.

This general picture emerges from recent work on the behavior of matter and forces in the very early stages of the development of the universe. It became clear that the giant cosmic repulsion is the inevitable result of the Superpower. So, the "anti-gravity" that Einstein drove through the door has returned through the window!

The key to understanding the new discovery of cosmic repulsion is given by the nature of the quantum vacuum. We have seen how such a repulsion can be due to an unusual invisible medium, indistinguishable from empty space, but with negative pressure. Today, physicists believe that these are the properties of the quantum vacuum.

In Chapter 7 it was noted that the vacuum should be considered as a kind of "enzyme" of quantum activity, teeming with virtual particles and saturated with complex interactions. It is very important to understand that vacuum plays a decisive role in the framework of the quantum description. What we call particles are just rare disturbances, like "bubbles" on the surface of a whole sea of ​​activity.

At the end of the 1970s, it became obvious that the unification of the four interactions required a complete revision of ideas about the physical nature of the vacuum. The theory suggests that the vacuum energy manifests itself by no means unambiguously. Simply put, the vacuum can be excited and be in one of many states with very different energies, just as an atom can be excited by going to higher energy levels. These vacuum eigenstates - if we could observe them - would look exactly the same, although they have completely different properties.

First of all, the energy contained in the vacuum flows in huge quantities from one state to another. In Grand Unified Theories, for example, the difference between the lowest and highest vacuum energies is unimaginably large. To get some idea of ​​the gigantic scale of these quantities, let us estimate the energy released by the Sun over the entire period of its existence (about 5 billion years). Imagine that all this colossal amount of energy emitted by the Sun is enclosed in a region of space smaller in size than the Solar System. The energy densities achieved in this case are close to the energy densities corresponding to the state of vacuum in HWO.

Along with amazing energy differences, equally gigantic pressure differences correspond to different vacuum states. But here lies the "trick": all these pressures - negative. The quantum vacuum behaves exactly like the previously mentioned hypothetical cosmic repulsive medium, only this time the numerical values ​​of the pressure are so great that the repulsion is 10^120 times greater than the force that Einstein needed to maintain equilibrium in a static universe.

The way is now open for explaining the Big Bang. Let us assume that the Universe was in the beginning in an excited state of vacuum, which is called a "false" vacuum. In this state, there was a cosmic repulsion in the Universe of such magnitude that it would have caused the unrestrained and rapid expansion of the Universe. In essence, in this phase the Universe would correspond to the de Sitter model discussed in the previous section. The difference, however, is that in de Sitter the universe is quietly expanding on astronomical timescales, while the "de Sitter phase" in the evolution of the universe out of the "false" quantum vacuum is actually far from quiet. The volume of space occupied by the Universe should in this case double every 10^-34 s (or a time interval of the same order).

Such a super-expansion of the Universe has a number of characteristic features: all distances increase according to an exponential law (we already met with the concept of an exponent in Chapter 4). This means that every 10^-34 s all regions of the universe double their size, and then this process of doubling continues exponentially. This type of extension, first considered in 1980. Alan Guth of MIT (Massachusetts Institute of Technology, USA), was called by him "inflation". As a result of an extremely fast and continuously accelerating expansion, it would very soon turn out that all parts of the universe are flying apart, as in an explosion. And this is the Big Bang!

However, one way or another, but the phase of inflation must stop. As in all excited quantum systems, the "false" vacuum is unstable and tends to decay. When decay occurs, the repulsion disappears. This, in turn, leads to the cessation of inflation and the transition of the universe into the power of the usual gravitational attraction. Of course, in this case the Universe would continue to expand due to the initial impulse acquired during the period of inflation, but the rate of expansion would steadily decrease. Thus, the only trace that has survived to this day from cosmic repulsion is a gradual slowdown in the expansion of the Universe.

According to the "inflationary scenario", the Universe began its existence from a state of vacuum, devoid of matter and radiation. But, even if they were present from the beginning, their traces would quickly be lost due to the huge rate of expansion in the inflationary phase. In the extremely short period of time corresponding to this phase, the region of space occupied by the entire observable Universe today has grown from a billionth of the size of a proton to several centimeters. The density of any originally existing substance would actually become equal to zero.

So, by the end of the inflation phase, the universe was empty and cold. However, when inflation dried up, the universe suddenly became extremely "hot". This burst of heat that lit up the cosmos is due to the huge reserves of energy contained in the "false" vacuum. When the vacuum state collapsed, its energy was released in the form of radiation, which instantly heated the Universe to about 10^27 K, which is enough for processes to occur in the GUT. From that moment on, the universe has evolved according to the standard theory of the "hot" Big Bang. Thanks to thermal energy, matter and antimatter arose, then the Universe began to cool, and gradually all its elements observed today began to “freeze out”.

So the hard problem is what caused the Big Bang? - managed to solve using the theory of inflation; empty space spontaneously exploded under the repulsion inherent in the quantum vacuum. However, the mystery still remains. The colossal energy of the primary explosion, which went into the formation of matter and radiation existing in the Universe, had to come from somewhere! We will not be able to explain the existence of the universe until we find the source of primary energy.

space bootstrap

English bootstrap in the literal sense it means "lacing", in a figurative sense it means self-consistency, the absence of a hierarchy in the system of elementary particles.

The universe was born in the process of a gigantic outburst of energy. We still find traces of it - this is background thermal radiation and cosmic matter (in particular, atoms that make up stars and planets), which stores a certain energy in the form of "mass". Traces of this energy are also manifested in the recession of galaxies and in the violent activity of astronomical objects. Primary energy "started the spring" of the emerging Universe and continues to put it into action to this day.

Where did this energy come from, which breathed life into our Universe? According to the theory of inflation, this is the energy of empty space, in other words, the quantum vacuum. However, can such an answer fully satisfy us? It is natural to ask how the vacuum acquired energy.

In general, by asking where energy came from, we are essentially making an important assumption about the nature of that energy. One of the fundamental laws of physics is law of energy conservation, according to which various forms of energy can change and pass one into another, but the total amount of energy remains unchanged.

It is not difficult to give examples in which the operation of this law can be verified. Suppose we have an engine and a supply of fuel, and the engine is used to drive an electrical generator, which in turn powers the heater. During the combustion of fuel, the chemical energy stored in it is converted into mechanical, then into electrical, and finally into heat. Or suppose an engine is used to lift a load to the top of a tower, after which the load falls freely; when hitting the ground, exactly the same amount of thermal energy is released as in the example with a heater. The fact is that, no matter how energy is transferred or how its form changes, it obviously cannot be created or destroyed. Engineers use this law in everyday practice.

If energy can neither be created nor destroyed, then how does primary energy arise? Isn't it just injected at the first moment (a kind of new initial condition accepted by ad hoc)? If so, why does the universe contain this amount of energy and not some other amount? There is about 10^68 J (joules) of energy in the observable Universe - why not, say, 10^99 or 10^10000 or any other number?

The theory of inflation offers one possible scientific explanation for this puzzle. According to this theory. The Universe initially had an energy that was actually equal to zero, and in the first 10^32 seconds it succeeded in bringing to life the entire gigantic amount of energy. The key to understanding this miracle is to be found in the remarkable fact that the law of conservation of energy in the usual sense not applicable to the expanding universe.

In fact, we have already met with a similar fact. Cosmological expansion leads to a decrease in the temperature of the Universe: accordingly, the energy of thermal radiation, which is so large in the primary phase, is depleted and the temperature drops to values ​​close to absolute zero. Where did all this heat energy go? In a sense, it was used up by the universe to expand and provided pressure to supplement the force of the Big Bang. When an ordinary liquid expands, its outward pressure does work using the energy of the liquid. When an ordinary gas expands, its internal energy is spent on doing work. In complete contrast to this, cosmic repulsion is similar to the behavior of a medium with negative pressure. When such a medium expands, its energy does not decrease, but increases. This is exactly what happened during the period of inflation, when the cosmic repulsion caused the Universe to expand rapidly. Throughout this period, the total energy of the vacuum continued to increase until, by the end of the inflation period, it reached an enormous value. Once the period of inflation ended, all the stored energy was released in one giant burst, generating heat and matter on the full scale of the Big Bang. From that point on, the usual expansion with positive pressure began, so that the energy began to decrease again.

The emergence of primary energy is marked by some kind of magic. Vacuum with a mysterious negative pressure, is endowed, apparently, with absolutely incredible possibilities. On the one hand, it creates a gigantic repulsive force that ensures its ever-accelerating expansion, and on the other hand, the expansion itself forces an increase in the vacuum energy. The vacuum, in essence, feeds itself with energy in huge quantities. It has an internal instability that ensures continuous expansion and unlimited energy production. And only the quantum decay of a false vacuum puts a limit to this "cosmic extravagance".

Vacuum serves nature as a magical, bottomless jar of energy. In principle, there is no limit to the amount of energy that could be released during inflationary expansion. This statement marks a revolution in traditional thinking with its centuries-old “nothing will be born from nothing” (this saying dates at least from the Parmenid era, i.e. the 5th century BC). The idea of ​​the possibility of "creation" from nothing until recently was entirely within the competence of religions. In particular, Christians have long believed that God created the world out of Nothing, but the idea of ​​the possibility of the spontaneous emergence of all matter and energy as a result of purely physical processes was considered by scientists absolutely unacceptable a dozen years ago.

Those who cannot internally come to terms with the whole concept of the emergence of "something" from "nothing" have the opportunity to look differently at the emergence of energy during the expansion of the Universe. Since ordinary gravity has the character of attraction, in order to remove parts of matter from each other, it is necessary to do work to overcome the gravity acting between these parts. This means that the gravitational energy of the system of bodies is negative; when new bodies are added to the system, energy is released, and as a result, gravitational energy becomes "even more negative." If we apply this reasoning to the Universe at the stage of inflation, then it is the appearance of heat and matter that, as it were, "compensates" the negative gravitational energy of the formed masses. In this case, the total energy of the Universe as a whole is equal to zero and no new energy arises at all! Such a view of the process of "creation of the world" is certainly attractive, but it still should not be taken too seriously, since in general the status of the concept of energy in relation to gravity turns out to be doubtful.

Everything said here about the vacuum is very reminiscent of the favorite story of physicists about a boy who, having fallen into a swamp, pulled himself out by his own shoelaces. The self-creating universe resembles this boy - it also pulls itself out by its own "laces" (this process is denoted by the term "bootstrap"). Indeed, due to its own physical nature, the Universe excites in itself all the energy necessary for the “creation” and “revitalization” of matter, and also initiates the explosion that generates it. This is the space bootstrap; to his amazing power we owe our existence.

Advances in inflation theory

After Guth put forward the fundamental idea that the universe underwent an early period of extremely rapid expansion, it became clear that such a scenario could beautifully explain many features of the Big Bang cosmology that had previously been taken for granted.

In one of the preceding sections, we met with the paradoxes of a very high degree of organization and coordination of the primary explosion. One of the great examples of this is the force of the explosion, which turned out to be exactly “fitted” to the magnitude of the cosmic gravity, as a result of which the expansion rate of the Universe in our time is very close to the boundary value separating compression (collapse) and rapid expansion. The decisive test of the inflationary scenario is precisely whether it provides for a Big Bang of such a precisely defined force. It turns out that due to the exponential expansion in the inflation phase (which is its most characteristic property), the force of the explosion automatically strictly ensures the possibility of overcoming the Universe's own gravity. Inflation can lead exactly to the rate of expansion that is observed in reality.

Another "great mystery" has to do with the homogeneity of the universe on a large scale. It is also immediately solved on the basis of inflation theory. Any initial inhomogeneities in the structure of the universe must absolutely be erased with a grandiose increase in its size, just as the wrinkles on a deflated balloon are smoothed out when it is inflated. And as a result of an increase in the size of spatial regions by about 10^50 times, any initial perturbation becomes insignificant.

However, it would be wrong to talk about complete homogeneity. To make possible the emergence of modern galaxies and galaxy clusters, the structure of the early universe had to have some "lumpyness". Initially, astronomers hoped that the existence of galaxies could be explained by the accumulation of matter under the influence of gravitational attraction after the Big Bang. A cloud of gas must contract under its own gravity, and then break up into smaller fragments, and those, in turn, into even smaller ones, and so on. It is possible that the distribution of gas that arose as a result of the Big Bang was completely homogeneous, but due to purely random processes, thickening and rarefaction arose here and there due to purely random processes. Gravity further enhanced these fluctuations, leading to the growth of areas of condensation and absorption of additional matter by them. Then these regions contracted and successively disintegrated, and the smallest clumps turned into stars. In the end, a hierarchy of structures arose: stars united into groups, those into galaxies and further into clusters of galaxies.

Unfortunately, if there were no inhomogeneities in the gas from the very beginning, then such a mechanism for the emergence of galaxies would have worked in a time much longer than the age of the Universe. The fact is that the processes of condensation and fragmentation competed with the expansion of the Universe, which was accompanied by gas scattering. In the original version of the Big Bang theory, it was assumed that the "germs" of galaxies existed initially in the structure of the Universe at its origin. Moreover, these initial inhomogeneities had to have quite definite dimensions: not too small, otherwise they would never have formed, but not too large, otherwise the regions of high density would simply collapse, turning into huge black holes. At the same time, it is completely incomprehensible why galaxies have exactly such sizes or why such a number of galaxies is included in the cluster.

The inflationary scenario provides a more consistent explanation for galactic structure. The main idea is quite simple. Inflation is due to the fact that the quantum state of the Universe is an unstable state of false vacuum. Eventually, this vacuum state breaks down and its excess energy is converted into heat and matter. At this moment, the cosmic repulsion disappears - and inflation stops. However, the decay of a false vacuum does not occur strictly simultaneously in all space. As in any quantum process, the false vacuum decay rates fluctuate. In some regions of the universe, decay occurs somewhat faster than in others. In these areas, inflation will end earlier. As a result, the inhomogeneities are preserved in the final state as well. It is possible that these inhomogeneities could serve as "germs" (centers) of gravitational contraction and, in the end, led to the formation of galaxies and their clusters. Mathematical modeling of the mechanism of fluctuations has been carried out, however, with very limited success. As a rule, the effect turns out to be too large, and the calculated inhomogeneities are too significant. True, too coarse models were used and perhaps a more subtle approach would have been more successful. Although the theory is far from complete, it at least describes the nature of the mechanism that could lead to the formation of galaxies without the need for special initial conditions.

In Guth's version of the inflationary scenario, the false vacuum first turns into a "true" or lowest-energy vacuum state, which we identify with empty space. The nature of this change is quite similar to a phase transition (for example, from a gas to a liquid). In this case, in a false vacuum, bubbles of a true vacuum would randomly form, which, expanding at the speed of light, would capture all large areas of space. In order for the false vacuum to exist long enough for inflation to do its "miraculous" work, these two states must be separated by an energy barrier through which the "quantum tunneling" of the system must occur, similar to how it happens with electrons (see Chap.) . However, this model has one serious drawback: all the energy released from the false vacuum is concentrated in the bubble walls and there is no mechanism for its redistribution throughout the bubble. As the bubbles collided and merged, the energy would eventually accumulate in the randomly mixed layers. As a result, the universe would contain very strong inhomogeneities, and the entire work of inflation to create large-scale uniformity would collapse.

With further improvement of the inflationary scenario, these difficulties were overcome. The new theory lacks tunneling between two vacuum states; instead, the parameters are chosen so that the decay of the false vacuum is very slow, and thus the universe gets enough time to inflate. When the decay is completed, the false vacuum energy is released in the entire volume of the “bubble”, which quickly heats up to 10^27 K. It is assumed that the entire observable Universe is contained in one such bubble. Thus, at ultra-large scales, the universe may be highly irregular, but the region accessible to our observation (and even much larger parts of the universe) lies within a completely homogeneous zone.

It is curious that Guth originally developed his inflationary theory to solve a completely different cosmological problem - the absence of magnetic monopoles in nature. As shown in Chapter 9, the standard Big Bang theory predicts that in the primary phase of the evolution of the Universe, monopoles should arise in excess. They may be accompanied by their one- and two-dimensional counterparts - strange objects that have the character of "string" and "leaf". The problem was to rid the universe of these "undesirable" objects. Inflation automatically solves the problem of monopoles and other similar problems, since the giant expansion of space effectively reduces their density to zero.

Although the inflationary scenario has been developed only partially and is only plausible, no more, it has allowed the formulation of a number of ideas that promise to irrevocably change the face of cosmology. Now we can not only offer an explanation for the cause of the Big Bang, but also begin to understand why it was so "big" and why it took on such a character. We can now begin to solve the question of how the large-scale homogeneity of the Universe arose, and along with it, the observed inhomogeneities of a smaller scale (for example, galaxies). The primordial explosion that created what we call the universe is no longer a mystery beyond physical science.

Universe creating itself

And yet, despite the huge success of the inflationary theory in explaining the origin of the universe, the mystery remains. How did the universe initially end up in a state of false vacuum? What happened before inflation?

A consistent, quite satisfactory scientific description of the origin of the universe should explain how space itself (more precisely, space-time) arose, which then underwent inflation. Some scientists are ready to admit that space always exists, others believe that this issue is generally beyond the scope of the scientific approach. And only a few claim more and are convinced that it is quite legitimate to raise the question of how space in general (and a false vacuum in particular) could literally arise from “nothing” as a result of physical processes that, in principle, can be studied.

As noted, we have only recently challenged the persistent belief that "nothing comes from nothing." The cosmic bootstrap is close to the theological concept of the creation of the world from nothing (ex nihilo). Without a doubt, in the world around us, the existence of some objects is usually due to the presence of other objects. So, the Earth arose from the protosolar nebula, which, in turn, from galactic gases, etc. If we happened to see an object that suddenly appeared "out of nothing", we, apparently, would perceive it as a miracle; for example, it would surprise us if we suddenly found a lot of coins, knives or sweets in a locked empty safe. In everyday life, we are accustomed to being aware that everything arises from somewhere or from something.

However, everything is not so obvious when it comes to less specific things. From what, for example, does a painting emerge? Of course, this requires a brush, paints and a canvas, but these are just tools. The manner in which a picture is painted - the choice of form, color, texture, composition - is not born with brushes and paints. This is the result of the creative imagination of the artist.

Where do thoughts and ideas come from? Thoughts, no doubt, are real and, apparently, always require the participation of the brain. But the brain only provides the realization of thoughts, and is not their cause. By itself, the brain generates thoughts no more than, for example, a computer - calculations. Thoughts can be caused by other thoughts, but this does not reveal the nature of the thought itself. Some thoughts can be born, sensations; thought gives rise to memory. Most artists, however, view their work as the result of unexpected inspiration. If this is true, then the creation of a painting - or at least the birth of its idea - is just an example of the birth of something from nothing.

And yet, can we consider that physical objects and even the Universe as a whole arise from nothing? This bold hypothesis is being seriously discussed, for example, in scientific institutions on the east coast of the United States, where quite a few theoretical physicists and cosmologists are developing a mathematical apparatus that would help to find out the possibility of creating something from nothing. This elite circle includes Alan Guth of MIT, Sydney Coleman of Harvard University, Alex Vilenkin of Tufts University, Ed Tyon, and Heinz Pagels of New York. They all believe that in one sense or another "nothing is unstable" and that the physical universe spontaneously "bloomed out of nothing", governed only by the laws of physics. “Such ideas are purely speculative,” Guth admits, “but on a certain level they may be correct ... It is sometimes said that there is no free lunch, but the Universe, apparently, is just such a“ free lunch.

In all these hypotheses, quantum behavior plays a key role. As we said in Chapter 2, the main feature of quantum behavior is the loss of a strict causal relationship. In classical physics, the exposition of mechanics followed the strict observance of causality. All details of the motion of each particle were strictly predetermined by the laws of motion. It was believed that the movement is continuous and strictly determined by the acting forces. The laws of motion literally embodied the relationship between cause and effect. The universe was seen as a gigantic clockwork, whose behavior is strictly regulated by what is happening at the moment. It was the belief in such a comprehensive and absolutely strict causality that prompted Pierre Laplace to argue that a super-powerful calculator is capable, in principle, of predicting, on the basis of the laws of mechanics, both the history and the fate of the universe. According to this view, the universe is doomed to follow its prescribed path forever.

Quantum physics has destroyed the methodical but fruitless Laplacian scheme. Physicists have become convinced that, at the atomic level, matter and its motion are uncertain and unpredictable. Particles can behave "crazy", as if resisting strictly prescribed movements, suddenly appearing in the most unexpected places for no apparent reason, and sometimes appearing and disappearing "without warning".

The quantum world is not completely free from causality, but it manifests itself rather indecisively and ambiguously. For example, if one atom, as a result of a collision with another atom, finds itself in an excited state, it, as a rule, quickly returns to the state with the lowest energy, emitting a photon in the process. The appearance of a photon is, of course, a consequence of the fact that the atom has previously passed into an excited state. We can say with certainty that it was the excitation that led to the appearance of the photon, and in this sense the connection of cause and effect is preserved. However, the true moment of occurrence of a photon is unpredictable: an atom can emit it at any moment. Physicists are able to calculate the probable, or average, time of occurrence of a photon, but in any given case it is impossible to predict the moment when this event will occur. Apparently, to characterize such a situation, it is best to say that the excitation of an atom does not so much lead to the appearance of a photon as "pushing" it towards it.

Thus, the quantum microworld is not entangled in a dense web of causal relationships, but nevertheless "listens" to numerous unobtrusive commands and suggestions. In the old Newtonian scheme, the force, as it were, turned to the object with an unanswerable command: “Move!”. In quantum physics, the relationship between force and object is based on an invitation rather than a command.

Why do we find the idea of ​​the sudden birth of an object “out of nothing” so unacceptable at all? What then makes us think of miracles and supernatural phenomena? Perhaps the whole point is only in the unusualness of such events: in everyday life we ​​never encounter the unreasonable appearance of objects. When, for example, a magician pulls a rabbit out of a hat, we know that we are being fooled.

Let's assume that we really live in a world where objects appear "out of nowhere" from time to time, for no reason, and in a completely unpredictable way. Once accustomed to such phenomena, we would cease to be surprised by them. Spontaneous birth would be perceived as one of the whims of nature. Perhaps, in such a world, we would no longer have to strain our credulity to imagine the sudden emergence of the entire physical universe from nothing.

This imaginary world is essentially not so different from the real one. If we could directly perceive the behavior of atoms through our senses (and not through the mediation of special instruments), we would often have to observe objects appearing and disappearing without clearly defined reasons.

The phenomenon closest to "birth from nothing" occurs in a sufficiently strong electric field. At a critical value of the field strength, electrons and positrons begin to appear “out of nothing” in a completely random way. Calculations show that near the surface of the uranium nucleus, the electric field strength is sufficiently close to the limit beyond which this effect occurs. If there were atomic nuclei containing 200 protons (there are 92 of them in the nucleus of uranium), then spontaneous birth of electrons and positrons would occur. Unfortunately, a nucleus with such a large number of protons seems to become extremely unstable, but this is not completely certain.

The spontaneous production of electrons and positrons in a strong electric field can be considered as a special kind of radioactivity, when the decay experiences empty space, vacuum. We have already spoken about the transition from one vacuum state to another as a result of decay. In this case, the vacuum decays, turning into a state in which particles are present.

Although the disintegration of space caused by an electric field is difficult to comprehend, a similar process under the influence of gravity could well occur in nature. Near the surface of black holes, gravity is so strong that the vacuum is teeming with continuously born particles. This is the famous black hole radiation discovered by Stephen Hawking. Ultimately, it is gravity that is responsible for the birth of this radiation, but it cannot be said that this happens "in the old Newtonian sense": one cannot say that any particular particle should appear in a certain place at a particular moment in time as a result of the action of gravitational forces . In any case, since gravity is only a curvature of space-time, it can be said that space-time causes the birth of matter.

The spontaneous emergence of matter from empty space is often referred to as the birth "out of nothing", which is close in spirit to birth. ex nihilo in Christian doctrine. However, for a physicist, empty space is not “nothing” at all, but a very essential part of the physical Universe. If we still want to answer the question of how the universe came into being, then it is not enough to assume that empty space existed from the very beginning. It is necessary to explain where this space came from. thought of birth space itself It may seem strange, but in a sense it happens all the time around us. The expansion of the universe is nothing but the continuous "swelling" of space. Every day, the region of the universe accessible to our telescopes increases by 10 ^ 18 cubic light years. Where does this space come from? The rubber analogy is useful here. If the elastic rubber band is pulled out, it "gets bigger". Space resembles superelasticity in that, as far as we know, it can stretch indefinitely without tearing.

The stretching and curvature of space resembles the deformation of an elastic body in that the “movement” of space occurs according to the laws of mechanics in exactly the same way as the movement of ordinary matter. In this case, these are the laws of gravity. Quantum theory is equally applicable to matter, as well as to space and time. In previous chapters, we have said that quantum gravity is seen as a necessary step in the search for the Superpower. In this connection, a curious possibility arises; if, according to quantum theory, particles of matter can arise “out of nothing,” then, in relation to gravity, will it not describe the emergence “out of nothing” and space? If this happens, then isn't the birth of the Universe 18 billion years ago an example of just such a process?

Free lunch?

The main idea of ​​quantum cosmology is the application of quantum theory to the universe as a whole: to space-time and matter; theorists take this idea especially seriously. At first glance, there is a contradiction here: quantum physics deals with the smallest systems, while cosmology deals with the largest. However, the universe was once also limited to a very small size, and hence quantum effects were extremely important back then. The results of the calculations indicate that quantum laws should be taken into account in the GUT era (10^-32 s), and in the Planck era (10^-43 s) they should probably play a decisive role. According to some theorists (for example, Vilenkin), between these two epochs there was a moment in time when the Universe arose. According to Sydney Coleman, we have made a quantum leap from Nothing to Time. Apparently, space-time is a relic of this era. The quantum leap that Coleman talks about can be seen as a kind of "tunneling process". We noted that in the original version of the theory of inflation, the false vacuum state had to tunnel through the energy barrier to the true vacuum state. However, in the case of the spontaneous emergence of the quantum universe "out of nothing", our intuition reaches the limit of its capabilities. One end of the tunnel represents the physical universe in space and time, which gets there by quantum tunneling "out of nothing". Therefore, the other end of the tunnel is this very Nothing! Perhaps it would be better to say that the tunnel has only one end, and the other simply "does not exist."

The main difficulty of these attempts to explain the origin of the Universe lies in the description of the process of its birth from a state of false vacuum. If the newly emerged space-time were in a state of true vacuum, then inflation could never occur. The big bang would be reduced to a weak burst, and space-time would cease to exist again a moment later - it would be destroyed by the very quantum processes due to which it originally arose. If the Universe had not found itself in a state of false vacuum, it would never have become involved in the cosmic bootstrap and would not have materialized its illusory existence. Perhaps the false vacuum state is favored due to its extreme conditions. For example, if the universe began at a sufficiently high initial temperature and then cooled down, then it could even “run aground” in a false vacuum, but so far many technical questions of this type remain unresolved.

But whatever the reality of these fundamental problems, the universe must come into existence in one way or another, and quantum physics is the only branch of science in which it makes sense to talk about an event occurring for no apparent reason. If we are talking about space-time, then in any case it is meaningless to talk about causality in the usual sense. Usually, the concept of causality is closely related to the concept of time, and therefore any considerations about the processes of the emergence of time or its “exit from non-existence” must be based on a broader idea of ​​causality.

If space is really ten-dimensional, then the theory considers all ten dimensions to be quite equal in the earliest stages. It is attractive to associate the phenomenon of inflation with spontaneous compactification (folding) of seven out of ten dimensions. According to this scenario, the "driving force" of inflation is a by-product of interactions that manifest themselves through additional dimensions of space. Further, ten-dimensional space could naturally evolve in such a way that during inflation, three spatial dimensions grow strongly at the expense of the other seven, which, on the contrary, shrink, becoming invisible? Thus, the quantum microbubble of ten-dimensional space is compressed, and due to this, three dimensions are inflated, forming the Universe: the remaining seven dimensions remain in the captivity of the microcosm, from where they appear only indirectly - in the form of interactions. This theory seems very attractive.

Despite the fact that theorists still have a lot of work to do in studying the nature of the very early Universe, it is already possible to give a general outline of the events that resulted in the Universe becoming observable today. At the very beginning, the Universe spontaneously arose “out of nothing”. Thanks to the ability of quantum energy to serve as a kind of enzyme, the bubbles of empty space could inflate at an ever-increasing rate, creating enormous reserves of energy thanks to the bootstrap. This false vacuum, filled with self-generated energy, turned out to be unstable and began to decay, releasing energy in the form of heat, so that each bubble was filled with fire-breathing matter (fireball). The inflation (inflation) of the bubbles stopped, but the Big Bang began. On the "clock" of the Universe at that moment it was 10^-32 s.

From such a fireball, all matter and all physical objects arose. As the space material cooled, it experienced successive phase transitions. With each of the transitions, more and more different structures were “frozen out” from the primary shapeless material. One by one, the interactions separated from each other. Step by step, the objects that we now call subatomic particles acquired their present features. As the composition of the "cosmic soup" became more and more complicated, the large-scale irregularities left over from the time of inflation grew into galaxies. In the process of the further formation of structures and the separation of various types of matter, the Universe more and more acquired familiar forms; the hot plasma condensed into atoms, forming stars, planets and, ultimately, life. Thus the Universe "realized" itself.

Substance, energy, space, time, interactions, fields, orderliness and structure - all these concepts, borrowed from the "price list of the creator", serve as integral characteristics of the universe. The new physics opens up the tempting possibility of a scientific explanation of the origin of all these things. We no longer need to specifically enter them “manually” from the very beginning. We can see how all the fundamental properties of the physical world can appear automatically as a consequence of the laws of physics, without having to assume the existence of highly specific initial conditions. The new cosmology claims that the initial state of the cosmos plays no role, since all information about it has been erased during inflation. The Universe we observe bears only the imprints of those physical processes that have taken place since the beginning of inflation.

For thousands of years, humanity has believed that "nothing will be born out of nothing." Today we can say that everything came from nothing. You don't have to "pay" for the Universe - it's absolutely a "free lunch".

According to this theory, the Universe appeared in the form of a hot bunch of superdense matter, after which it began to expand and cool down. At the very first stage of evolution, the Universe was in a superdense state and was a -gluon plasma. If protons and neutrons collided and formed heavier nuclei, their time of existence was negligible. At the next collision with any fast particle, they immediately decayed into elementary components.

About 1 billion years ago, the formation of galaxies began, at that moment the Universe began to remotely resemble what we can see now. 300,000 years after the Big Bang, it cooled so much that the electrons became firmly held by the nuclei, as a result of which stable atoms appeared that did not decay immediately after colliding with another nucleus.

Particle formation

The formation of particles began as a result of the expansion of the universe. Its further cooling led to the formation of helium nuclei, which occurred as a result of primary nucleosynthesis. About three minutes should have passed since the Big Bang before the Universe cooled down, and the impact energy decreased so much that the particles began to form stable nuclei. In the first three minutes, the Universe was a red-hot sea of ​​elementary particles.

The primary formation of nuclei did not last very long, after the first three minutes the particles moved away from each other so that collisions between them became extremely rare. In this short period of primary nucleosynthesis, deuterium appeared - a heavy isotope of hydrogen, the nucleus of which contains one proton and one. Simultaneously with deuterium, helium-3, helium-4 and a small amount of lithium-7 were formed. Increasingly heavier elements appeared at the stage of star formation.

After the birth of the universe

Approximately one hundred-thousandth of a second from the beginning of the birth of the Universe, quarks combined into elementary particles. From that moment on, the Universe became a cooling sea of ​​elementary particles. Following this, a process began that is called the great unification of fundamental forces. Then in the Universe there were energies corresponding to the maximum energies that can be obtained in modern accelerators. After that, an abrupt inflationary expansion began, and antiparticles disappeared at the same time.