How the Universe appeared: scientific approaches and versions. Theories of the origin of the universe and its models How the universe was created

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. All this is 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. Following this, periods of expansion and cooling occurred 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 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.

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 suggest about 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 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 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 a consensus 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. 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, 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 where this growth started. 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

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.
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.
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:

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.
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.
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.

One of the main questions that does not leave the human consciousness has always been and is the question: “how did the Universe appear?” Of course, there is no definite answer to this question, and it is unlikely to be obtained soon, but science is working in this direction and is forming a certain theoretical model of the origin of our Universe.

First of all, we should consider the basic properties of the Universe, which should be described within the framework of the cosmological model.

The model must take into account the observed distances between objects, as well as the speed and direction of their movement. Such calculations are based on Hubble's law: cz = H0D, where z is the redshift of the object, D is the distance to this object, c is the speed of light.
The age of the Universe in the model must exceed the age of the oldest objects in the world.
The model must take into account the initial abundance of elements.
The model must take into account the observed large-scale structure of the Universe.
The model must take into account the observed relict background.

Let us briefly consider the generally accepted theory of the origin and early evolution of the Universe, which is supported by most scientists. Today, the Big Bang theory refers to a combination of the hot Universe model with the Big Bang. And, although these concepts initially existed independently of each other, as a result of their unification it was possible to explain the original chemical composition of the Universe, as well as the presence of cosmic microwave background radiation.

According to this theory, the Universe arose about 13.77 billion years ago from some dense heated object - a singular state that is difficult to describe within the framework of modern physics. The problem with the cosmological singularity, among other things, is that when describing it, most physical quantities, such as density and temperature, tend to infinity. At the same time, it is known that at infinite density, entropy (a measure of chaos) should tend to zero, which is in no way compatible with infinite temperature.

Evolution of the Universe

The first 10 -43 seconds after the Big Bang are called the stage of quantum chaos. The nature of the universe at this stage of existence cannot be described within the framework of physics known to us. The continuous unified space-time disintegrates into quanta.

The Planck moment is the moment of the end of quantum chaos, which falls at 10 in -43 seconds. At this moment, the parameters of the Universe were equal to Planck values, such as the Planck temperature (about 1032 K). At the moment of the Planck era, all four fundamental interactions (weak, strong, electromagnetic and gravitational) were combined into a single interaction. It is not possible to consider the Planck moment as some long period, since modern physics does not work with parameters less than the Planck moment.
Inflation stage. The next stage in the history of the Universe was the inflationary stage. At the first moment of inflation, the gravitational interaction was separated from the single supersymmetric field (previously including the fields of fundamental interactions). During this period, matter has negative pressure, which causes an exponential increase in the kinetic energy of the Universe. Simply put, during this period the Universe began to inflate very quickly, and towards the end the energy of physical fields turns into the energy of ordinary particles. At the end of this stage, the temperature of the substance and radiation increases significantly. Along with the end of the inflation stage, a strong interaction also emerges. Also at this moment, the baryon asymmetry of the Universe arises.

[Baryonic asymmetry of the Universe is the observed phenomenon of the predominance of matter over antimatter in the Universe]

Stage of radiation dominance. The next stage in the development of the Universe, which includes several stages. At this stage, the temperature of the Universe begins to decrease, quarks are formed, then hadrons and leptons. In the era of nucleosynthesis, the formation of initial chemical elements occurs and helium is synthesized. However, radiation still dominates matter.
The era of substance dominance. After 10,000 years, the energy of the substance gradually exceeds the energy of radiation and their separation occurs. The matter begins to dominate the radiation, and a relict background appears. Also, the separation of matter with radiation significantly enhanced the initial inhomogeneities in the distribution of matter, as a result of which galaxies and supergalaxies began to form. The laws of the Universe have come to the form in which we observe them today.

The above picture is composed of several fundamental theories and gives a general idea of the formation of the Universe in the early stages of its existence.

Where did the Universe come from?

If the Universe arose from a cosmological singularity, then where did the singularity itself come from? It is currently impossible to give an exact answer to this question. Let us consider some cosmological models affecting the “birth of the Universe”.

These models are based on the assertion that the Universe has always existed and over time its state only changes, moving from expansion to compression - and back.

Steinhardt-Turok model. This model is based on string theory (M-theory), as it uses an object such as a “brane”.

[A brane (from membrane) in string theory (M-theory) is a hypothetical fundamental multidimensional physical object of dimension less than the dimension of the space in which it is located]

According to this model, the visible Universe is located inside a three-brane, which periodically, every few trillion years, collides with another three-brane, which causes something like the Big Bang. Next, our three-brane begins to move away from the other and expand. At some point, the share of dark energy takes precedence and the rate of expansion of the three-brane increases. The colossal expansion scatters matter and radiation so much that the world becomes almost homogeneous and empty. Eventually, the three-branes collide again, causing ours to return to the initial phase of its cycle, again giving birth to our “Universe.”

The theory of Loris Baum and Paul Frampton also states that the Universe is cyclical. According to their theory, the latter, after the Big Bang, will expand due to dark energy until it approaches the moment of “disintegration” of space-time itself - the Big Rip. As is known, in a “closed system, entropy does not decrease” (the second law of thermodynamics). From this statement it follows that the Universe cannot return to its original state, since during such a process entropy must decrease. However, this problem is solved within the framework of this theory. According to the theory of Baum and Frampton, a moment before the Big Rip, the Universe breaks up into many “shreds”, each of which has a rather small entropy value. Experiencing a series of phase transitions, these “flaps” of the former Universe generate matter and develop similarly to the original Universe. These new worlds do not interact with each other, as they fly apart at speeds greater than the speed of light. Thus, scientists also avoided the cosmological singularity with which the birth of the Universe begins, according to most cosmological theories. That is, at the moment of the end of its cycle, the Universe breaks up into many other non-interacting worlds, which will become new universes.
Conformal cyclic cosmology – cyclic model of Roger Penrose and Vahagn Gurzadyan. According to this model, the Universe is able to enter a new cycle without violating the second law of thermodynamics. This theory is based on the assumption that black holes destroy absorbed information, which in some way “legally” reduces the entropy of the Universe. Then each such cycle of the existence of the Universe begins with something similar to the Big Bang and ends with a singularity.

Other models of the origin of the Universe

Among other hypotheses explaining the appearance of the visible Universe, the following two are the most popular:

Chaotic theory of inflation - the theory of Andrei Linde. According to this theory, there is a certain scalar field that is inhomogeneous throughout its entire volume. That is, in different areas of the universe the scalar field has different meanings. Then, in areas where the field is weak, nothing happens, while areas with a strong field begin to expand (inflation) due to its energy, forming new universes. Such a scenario implies the existence of many worlds that did not arise simultaneously and have their own set of elementary particles, and, consequently, laws of nature.
Lee Smolin's theory suggests that the Big Bang is not the beginning of the existence of the Universe, but is only a phase transition between its two states. Since before the Big Bang the Universe existed in the form of a cosmological singularity, close in nature to the singularity of a black hole, Smolin suggests that the Universe could have arisen from a black hole.

There are also models in which universes arise continuously, bud off from their parents and find their own place. Moreover, it is not at all necessary that the same physical laws are established in such worlds. All these worlds are “embedded” in a single space-time continuum, but they are so separated in it that they do not sense each other’s presence. In general, the concept of inflation allows—indeed, forces!—to consider that in the gigantic megacosmos there are many universes isolated from each other with different structures.

Despite the fact that cyclic and other models answer a number of questions that cannot be answered by the Big Bang theory, including the problem of cosmological singularity. Yet, when combined with the inflationary theory, the Big Bang more fully explains the origin of the Universe, and also agrees with many observations.

Today, researchers continue to intensively study possible scenarios for the origin of the Universe, however, it is impossible to give an irrefutable answer to the question “How did the Universe appear?” - is unlikely to succeed in the near future. There are two reasons for this: direct proof of cosmological theories is practically impossible, only indirect; Even theoretically, it is not possible to obtain accurate information about the world before the Big Bang. For these two reasons, scientists can only put forward hypotheses and build cosmological models that will most accurately describe the nature of the Universe we observe.

It's hard to imagine a time 13.7 billion years before today when the entire universe was a singularity. According to the Big Bang theory, one of the leading contenders for explaining where the universe and all the matter in space came from was all compressed into a point smaller than a subatomic particle. But if this can still be accepted, think about this: what happened before the Big Bang happened?

This question in modern cosmology goes back as far as the fourth century AD. 1600 years ago, theologian Augustine the Blessed tried to understand the nature of God before the creation of the Universe. And do you know what he came to? Time was part of God's creation and there simply was no “before.”

One of the best physicists of the 20th century, Albert Einstein, came to almost the same conclusions in developing his theory of relativity. It is enough to pay attention to the effect of mass on time. The planet's enormous mass distorts time, causing it to flow slower for a person on the surface than for an astronaut in orbit. The difference is too small to be obvious, but in fact, a person standing by a large rock ages slower than someone standing in a field. But it would take a billion years to become a second younger. The singularity before the big bang had all the mass of the universe, which effectively put time at a standstill.

According to Einstein's theory of relativity, time was born exactly at the moment when the singularity began to expand and went beyond the compressed infinity. Decades after Einstein's death, the development of quantum physics and a variety of new theories have renewed debate about the nature of the universe before the Big Bang. Let's get a look.

Branes, cycles and other ideas
“And God spat, left and slammed the door,
We were behind him - but the doors were gone.”
A. Nepomnyashchiy

What if our Universe is a descendant of another, older Universe? Some astrophysicists believe that relict radiation left over from the big bang: the cosmic microwave background will help shed light on this story.

Astronomers first detected the cosmic microwave background radiation in 1965, and it gave rise to certain problems in the big bang theory - problems that caused scientists to briefly (until 1981) become confused and develop the inflationary theory. According to this theory, in the first moments of its existence, the Universe began to expand extremely rapidly. The theory also explains the temperature and density of CMB fluctuations and suggests that these fluctuations should be the same.

But, as it turned out, no. Recent research has made it clear that the Universe is actually one-sided, with some areas experiencing more fluctuations than others. Some cosmologists believe that this observation confirms that our Universe had a “mother”(!)

In the theory of chaotic inflation, this idea gains momentum: the endless progress of inflation bubbles generates an abundance of universes, and each of them generates even more inflation bubbles in a huge number of Multiverses.

However, there are models that try to explain the formation of the singularity before the big bang. If you think of black holes as giant garbage bins, they are prime candidates for primordial collapse, so our expanding Universe could very well be a white hole - a black hole exit hole, and each black hole in our Universe could house a different universe.

Other scientists believe that behind the formation of the singularity is a cycle called the “big bang,” in which the expanding universe eventually collapses in on itself, giving rise to another singularity, which, again, gives rise to another big bang. This process will be eternal, and all singularities and all collapses will not represent anything other than a transition to another phase of the existence of the Universe.

The last explanation we'll look at uses the idea of a cyclic universe generated by string theory. It suggests that new matter and energy flows are created every trillions of years when two membranes, or branes, beyond our dimensions collide with each other.

What happened before the Big Bang? The question remains open. Maybe nothing. Maybe another Universe or another version of ours. Maybe an ocean of Universes, each of which has its own set of laws and constants that dictate the nature of physical reality.

Stellar masses... Our science is confused and at the same time fascinated by these colossal bodies that behave like atoms, but whose construction baffles us with its enormous and (only apparently?) haphazard complexity. Perhaps, over time, some order or periodicity will emerge in the structure of stars, both in composition and location. (N.A. Sadovsky)

Let's raise our heads into the starry night. Somewhere there, behind the dark blue veil, it all began. And it all started, as usual, out of nothing. But we will start with the Big Bang, as Americans call the Big Bang that occurred in the Universe 15 billion years ago. We cannot even imagine what the Universe was like before this.

We have time. Even if the clocks break down all over the Earth, the Sun will rise and set, counting down solar days, tree rings will still form on trees, etc. Time will not stop. Now imagine that there is no time. Time has not stood still. It simply doesn't exist. There is no space either. No substance. There is a superclump of matter with colossal density. All the future matter of the world, everything that will later become stars, planets - everything is compressed into one point with an infinitely high temperature. Thus the Universe “began.” At the moment of this event, space and time were created.

It makes no sense to ask what happened before the Big Bang. It's like asking what is north of the North Pole or south of the South Pole. The question “Where did this happen?” can be answered with only one word: “everywhere.” Indeed, the Universe at that moment was not an isolated point in another space. She was all this point and its dimensions at that moment were very small - close to the size of an electron. Such a point can only be seen with a powerful electron microscope. But the mass is disproportionately large: not 100, not 1000, not even 1,000,000 tons - much more. More than the mass of the Earth, the Sun, one hundred thousand billion (100,000,000,000,000) times more than the mass of our entire Galaxy. And there is not so little in it - 150 billion stars weighing as much as the Sun and heavier!

Then this point “exploded” with enormous force, and a huge cloud consisting of elementary particles began to grow and expand in all directions. Each particle was heavy and lived a short but stormy life. The first stage of the formation of the Universe is called hadronic, and it lasted only a fraction of a second - one ten-thousandth of it (0.0001 s)! The expansion rate of the Universe exceeded the speed of light in a vacuum and approached 300,000,000 m/s (300,000 km/s). Compare: the initial speed of a bullet fired from a Kalashnikov assault rifle is 715 m/s, which is less than a kilometer per second, the first escape velocity is 8 km/s. A spaceship in orbit moves at approximately the same speed.

In the first moments of its existence, the Universe was very hot, much hotter than the interior of the hottest star. At temperatures above 10 billion degrees, which is exactly what the temperature of the Universe was, no substance can exist. Yes, he wasn’t there yet. Almost all the energy in the Universe existed in the form of electromagnetic radiation (photons), i.e. the Universe “glowed”, or more precisely, it was itself a bright and endless light.

Hadrons are the heaviest elementary particles. But now the time has come for lighter particles - leptons. The second stage has begun.

As you know, particles do not stand still, but move, collide, disappear, and change. As a result of such “dances,” particles and antiparticles arise. They cannot exist together. Here it’s who will win. By chance, the number of particles turned out to be slightly greater than the number of antiparticles. The particles “survived”, and the whole world is now built from them.

What would happen if the antiparticles won? Scientists answer: nothing special, the world would remain the same, only the structure of atoms would change slightly. “Our” atoms have a positively charged nucleus and negatively charged electron(s) on the shells. But it would be the other way around. And the electron would be called a positron... Scientists have long learned to obtain antiparticles in laboratory conditions, but antimatter is not found in a free state on Earth.

In 10 seconds, the Universe “slipped through” the second (lepton) stage with its thermonuclear reactions. The composition of the substance from which the world will consist has already been outlined. Hydrogen atoms and, later, helium nuclei appeared. In one day, the Universe lost its super-density. By the end of the first day, its density was 100 times lower than the density of ordinary air.

And that's where the world of high speeds ended. The third era - the era of radiation - lasted a million years. Although this is not much compared to the multi-billion-dollar life of the Universe, if compared with the rapid beginning that lasts only a few seconds, then yes, it is a lot. The relict radiation still detected in space reminds us of that era. Relict radiation is called the radiation of an absolutely black body at a temperature of 2.7 K. Yes, yes, don’t be surprised, an absolutely black body can also “radiate”. Imagine a hollow ball. Let's assume we start heating it up. What's going on inside? Our ball is empty. The “heat” inside such a cavity is electromagnetic waves rushing between the inner walls. If a body is heated to 6,000 °C, then the waves will appear mainly in the visible part of the spectrum. Our ball can be called a “black body”, since radiation does not pass through its walls, and it is “black” for an external observer, although it is heated inside. At different temperatures of a black body, the radiation is also different. At 6,000 °C it is visible green, at a temperature of about a million Kelvin it is x-ray radiation. At temperatures close to absolute zero (-273 °C) - microwaves. This is what happens in the Universe. CMB in this case is the memory of the third stage of the development of the universe - the era of radiation.

The era of radiation ended with the formation of matter, then another era began in which we live. This is the Age of Substance. Quasars, galaxies, stars, planetary systems are born - everything that we now observe from Earth.

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The model must take into account the observed distances between objects, as well as the speed and direction of their movement. Such calculations are based on Hubble's law: cz =H 0D, Where z- redshift of the object, D- distance to this object, c- speed of light.
The age of the Universe in the model must exceed the age of the oldest objects in the world.
The model must take into account the initial abundance of elements.
The model must take into account the observable.
The model must take into account the observed relict background.

Let us briefly consider the generally accepted theory of the origin and early evolution of the Universe, which is supported by most scientists. Today, the Big Bang theory refers to a combination of the hot Universe model with the Big Bang. And although these concepts initially existed independently of each other, as a result of their unification it was possible to explain the original chemical composition of the Universe, as well as the presence of cosmic microwave background radiation.

According to this theory, the Universe arose about 13.77 billion years ago from some dense heated object - difficult to describe within the framework of modern physics. The problem with the cosmological singularity, among other things, is that when describing it, most physical quantities, such as density and temperature, tend to infinity. At the same time, it is known that at infinite density (the measure of chaos) should tend to zero, which is in no way compatible with infinite temperature.

- The first 10-43 seconds after the Big Bang are called the stage of quantum chaos. The nature of the universe at this stage of existence cannot be described within the framework of physics known to us. The continuous unified space-time disintegrates into quanta.

The Planck moment is the moment of the end of quantum chaos, which falls at 10 -43 seconds. At this moment, the parameters of the Universe were equal to, like the Planck temperature (about 10 32 K). At the moment of the Planck era, all four fundamental interactions (weak, strong, electromagnetic and gravitational) were combined into a single interaction. It is not possible to consider the Planck moment as a certain long period, since modern physics does not work with parameters less than the Planck moment.
Stage. The next stage in the history of the Universe was the inflationary stage. At the first moment of inflation, the gravitational interaction was separated from the single supersymmetric field (previously including the fields of fundamental interactions). During this period, matter has negative pressure, which causes an exponential increase in the kinetic energy of the Universe. Simply put, during this period the Universe began to inflate very quickly, and towards the end, the energy of physical fields turns into the energy of ordinary particles. At the end of this stage, the temperature of the substance and radiation increases significantly. Along with the end of the inflation stage, a strong interaction also emerges. Also at this moment it arises.
Stage of radiation dominance. The next stage in the development of the Universe, which includes several stages. At this stage, the temperature of the Universe begins to decrease, quarks are formed, then hadrons and leptons. In the era of nucleosynthesis, the formation of initial chemical elements occurs and helium is synthesized. However, radiation still dominates matter.
The era of substance dominance. After 10,000 years, the energy of the substance gradually exceeds the energy of radiation and their separation occurs. The matter begins to dominate the radiation, and a relict background appears. Also, the separation of matter with radiation significantly enhanced the initial inhomogeneities in the distribution of matter, as a result of which galaxies and supergalaxies began to form. The laws of the Universe have come to the form in which we observe them today.

The above picture is composed of several fundamental theories and gives a general idea of the formation of the Universe in the early stages of its existence.

Where did the Universe come from?

Cyclic models

These models are based on the assertion that the Universe has always existed and over time its state only changes, moving from expansion to compression - and back.

Steinhardt-Turok model. This model is based on string theory (M-theory), as it uses an object such as a “brane”. According to this model, the visible Universe is located inside a 3-brane, which periodically, every few trillion years, collides with another 3-brane, which causes something like the Big Bang. Next, our 3-brane begins to move away from the other and expand. At some point, the share of dark energy takes precedence and the rate of expansion of the 3-brane increases. The colossal expansion scatters matter and radiation so much that the world becomes almost homogeneous and empty. Eventually, the 3-branes collide again, causing ours to return to the initial phase of its cycle, again giving birth to our “Universe.”

The theory of Loris Baum and Paul Frampton also states that the Universe is cyclical. According to their theory, the latter, after the Big Bang, will expand due to dark energy until it approaches the moment of “decay” of space-time itself - the Big Rip. As is known, in a “closed system, entropy does not decrease” (the second law of thermodynamics). From this statement it follows that the Universe cannot return to its original state, since during such a process entropy must decrease. However, this problem is solved within the framework of this theory. According to the theory of Baum and Frampton, a moment before the Big Rip, the Universe breaks up into many “shreds”, each of which has a rather small entropy value. Experiencing a series of phase transitions, these “flaps” of the former Universe generate matter and develop similarly to the original Universe. These new worlds do not interact with each other, as they fly apart at speeds greater than the speed of light. Thus, scientists also avoided the cosmological singularity with which the birth of the Universe begins, according to most cosmological theories. That is, at the moment of the end of its cycle, the Universe breaks up into many other non-interacting worlds, which will become new universes.
Conformal cyclic cosmology - cyclic model of Roger Penrose and Vahagn Gurzadyan. According to this model, the Universe is able to enter a new cycle without violating the second law of thermodynamics. This theory is based on the assumption that black holes destroy absorbed information, which in some way “legally” reduces the entropy of the Universe. Then each such cycle of the existence of the Universe begins with something similar to the Big Bang and ends with a singularity.

Other models of the origin of the Universe

Among other hypotheses explaining the appearance of the visible Universe, the following two are the most popular:

Chaotic theory of inflation - the theory of Andrei Linde. According to this theory, there is a certain scalar field that is inhomogeneous throughout its entire volume. That is, in different areas of the universe the scalar field has different meanings. Then, in areas where the field is weak, nothing happens, while areas with a strong field begin to expand (inflation) due to its energy, forming new universes. This scenario implies the existence of many worlds that arose non-simultaneously and have their own set of elementary particles, and, consequently, laws of nature.
Lee Smolin's theory suggests that the Big Bang is not the beginning of the existence of the Universe, but is only a phase transition between its two states. Since before the Big Bang the Universe existed in the form of a cosmological singularity, close in nature to the singularity of a black hole, Smolin suggests that the Universe could have arisen from a black hole.

Results

Today, researchers continue to intensively study possible scenarios for the origin of the Universe, however, it is impossible to give an irrefutable answer to the question “How did the Universe appear?” — is unlikely to succeed in the near future. There are two reasons for this: direct proof of cosmological theories is practically impossible, only indirect; Even theoretically, it is not possible to obtain accurate information about the world before the Big Bang. For these two reasons, scientists can only put forward hypotheses and build cosmological models that will most accurately describe the nature of the Universe we observe.