When the big bang happened. Experimental confirmation of the big bang theory. The universe is like a computer

The Big Bang theory has become almost as much a generally accepted cosmological model as the rotation of the Earth around the Sun. According to the theory, about 14 billion years ago, spontaneous oscillations in absolute emptiness led to the emergence of the universe. Something the size of a subatomic particle expanded to unimaginable sizes in a split second. But in this theory there are many problems over which physicists are struggling, putting forward more and more new hypotheses.

What's wrong with the big bang theory

It follows from the theory, that all the planets and stars were formed from dust scattered across space as a result of the explosion. But what preceded it is unclear: here our mathematical model of space-time ceases to work. The universe arose from an initial singular state to which modern physics cannot be applied. The theory also does not consider the reasons for the emergence of a singularity or matter and energy for its occurrence. It is believed that the answer to the question of the existence and origin of the initial singularity will be given by the theory of quantum gravity.

Most cosmological models predict that the complete universe is much larger than the observable portion - a spherical region with a diameter of about 90 billion light years. We see only that part of the Universe, the light from which managed to reach the Earth in 13.8 billion years. But telescopes are getting better, we are detecting more and more distant objects, and so far there is no reason to believe that this process will stop.

Since the Big Bang, the universe has been expanding with acceleration. The hardest riddle modern physics- the question of what causes the acceleration. The working hypothesis is that the universe contains an invisible component called "dark energy." The Big Bang theory does not explain whether the universe will expand indefinitely, and if so, what it will lead to - to its disappearance or something else.

Although Newtonian mechanics has been supplanted by relativistic physics, it cannot be called erroneous. However, the perception of the world and the models for describing the universe have completely changed. The Big Bang Theory predicted a number of things that were not known before. Thus, if another theory comes in its place, it should be similar and expand the understanding of the world.

We will focus on the most interesting theories describing alternative Big Bang models.

The universe is like a mirage of a black hole

The universe originated from the collapse of a star in a four-dimensional universe, say scientists from the Perimeter Institute for Theoretical Physics. The results of their research were published in Scientific American. Nyayesh Afshordi, Robert Mann and Razi Purhasan say that our three-dimensional universe has become a kind of "holographic mirage" when a four-dimensional star collapses. In contrast to the Big Bang theory, according to which the universe arose from extremely hot and dense space-time, where standard laws of physics do not apply, the new hypothesis about the four-dimensional universe explains both the reasons for the origin and its rapid expansion

According to the scenario formulated by Afshordi and his colleagues, our three-dimensional universe is a kind of membrane that floats through an even more voluminous universe that already exists in four dimensions. If four-dimensional stars of their own existed in this four-dimensional space, they would also explode, like the three-dimensional ones in our Universe. The inner layer would become a black hole, and the outer layer would be thrown into space.

In our universe, black holes are surrounded by a sphere called the event horizon. And if in three-dimensional space this border is two-dimensional (like a membrane), then in the four-dimensional universe the event horizon will be limited by a sphere that exists in three dimensions. Computer simulations of the collapse of a four-dimensional star have shown that its three-dimensional event horizon will gradually expand. This is what we observe, calling the growth of the 3D membrane the expansion of the Universe, astrophysicists believe.

Big freeze

An alternative to the Big Bang could be the Big Freeze. A team of physicists from the University of Melbourne, led by James Kvatch, presented a model of the birth of the Universe, which looks more like a gradual process of freezing amorphous energy than its splash and expansion in three directions of space.

Formless energy, according to scientists, like water, cooled to crystallization, creating the usual three spatial and one time dimensions.

The Big Freeze Theory casts doubt on Albert Einstein's currently accepted statement about the continuity and smoothness of space and time. It is possible that space has its constituent parts - indivisible building blocks like tiny atoms or pixels in computer graphics. These blocks are so small that they cannot be observed, however, following the new theory, it is possible to detect defects that should refract flows of other particles. Scientists have calculated such effects using a mathematical apparatus, and now they will try to detect them experimentally.

A universe without beginning or end

Ahmed Farag Ali of Benha University in Egypt and Sauria Das of Lethbridge University in Canada have proposed a new solution to the singularity problem by ditching the Big Bang. They brought in the ideas of the famous physicist David Bohm into the Friedman equation describing the expansion of the Universe and the Big Bang. “It's amazing that small amendments can potentially solve so many issues,” says Das.

The resulting model combines general relativity and quantum theory. She not only denies the singularity that preceded the Big Bang, but also does not allow the universe to contract back to its original state over time. According to the data obtained, the universe has a finite size and an infinite lifetime. In physical terms, the model describes the Universe filled with a hypothetical quantum fluid, which consists of gravitons - particles that provide gravitational interaction.

Scientists also claim that their findings are consistent with the latest measurements of the density of the universe.

Endless chaotic inflation

The term "inflation" refers to the rapid expansion of the universe, which occurred exponentially in the first moments after the Big Bang. By itself, the theory of inflation does not refute the theory of the Big Bang, but only interprets it differently. This theory solves several fundamental problems in physics.

According to the inflationary model, shortly after birth, the universe is very a short time expanded exponentially: its size doubled many times. Scientists believe that in 10 to -36 degrees of seconds, the Universe has increased in size at least 10 to 30-50 times, and possibly more. At the end of the inflationary phase, the Universe was filled with a superhot plasma of free quarks, gluons, leptons and high-energy quanta.

The concept implies what exists in the world many isolated universes with different device

Physicists have come to the conclusion that the logic of the inflationary model does not contradict the idea of ​​constant multiple birth of new universes. Quantum fluctuations - the same as those that gave rise to our world - can occur in any quantity, if there are suitable conditions for this. It is quite possible that our universe emerged from the fluctuation zone formed in the predecessor world. It can also be assumed that sometime and somewhere in our Universe a fluctuation will form, which will “blow out” a young universe of a completely different kind. In this model, the child universes can continually bud off. At the same time, it is not at all necessary that the same physical laws... The concept implies that in the world there are many isolated universes with different devices.

Cyclic theory

Paul Steinhardt, one of the physicists who laid the foundations of inflationary cosmology, decided to develop this theory further. The scientist who heads the Center for Theoretical Physics in Princeton, together with Neil Turok of the Perimeter Institute for Theoretical Physics, laid out an alternative theory in the book Endless Universe: Beyond the Big Bang ("Infinite Universe: Beyond the Big Bang"). Their model is based on a generalization of quantum superstring theory known as M-theory. According to her, physical world has 11 dimensions - ten spatial and one temporal. Spaces of lower dimensions "float" in it, the so-called branes (short for "membrane"). Our universe is just one of those branes.

The Steinhardt and Turok model argues that the Big Bang occurred as a result of the collision of our brane with another brane - an unknown universe. In this scenario, collisions occur endlessly. According to the hypothesis of Steinhardt and Turok, another three-dimensional brane "floats" next to our brane, separated by a tiny distance. It also expands, flattens and empties, but after a trillion years the branes will begin to converge and eventually collide. This will release a huge amount of energy, particles and radiation. This cataclysm will launch another cycle of expansion and cooling of the Universe. It follows from the Steinhardt and Turok model that these cycles were in the past and will certainly repeat in the future. How these cycles began, the theory is silent.

Universe
like a computer

Another hypothesis about the structure of the universe says that our entire world is nothing more than a matrix or a computer program. The idea that the universe is a digital computer was first put forward by German engineer and computer pioneer Konrad Zuse in his book Calculating Space ("Computing space"). Among those who also viewed the universe as a giant computer are physicists Stephen Wolfram and Gerard 't Hooft.

Digital physics theorists assume that the universe is essentially information and therefore computable. It follows from these assumptions that the universe can be viewed as the result of a computer program or digital computing device. This computer could be, for example, a giant cellular automaton or a universal Turing machine.

Indirect evidence virtual nature of the universe called the uncertainty principle in quantum mechanics

According to the theory, every object and event of the physical world comes from asking questions and registering answers "yes" or "no". That is, behind everything that surrounds us, a certain code is hidden, similar to the binary code of a computer program. And we are a kind of interface through which access to the data of the "universal Internet" appears. The principle of uncertainty in quantum mechanics is called an indirect proof of the virtual nature of the Universe: particles of matter can exist in an unstable form, and are "fixed" in a specific state only when observing them.

The follower of digital physics John Archibald Wheeler wrote: “It would not be unreasonable to imagine that information is in the core of physics as well as in the core of a computer. Everything from a bit. In other words, everything that exists - every particle, every field of force, even the space-time continuum itself - gets its function, its meaning and, ultimately, its very existence. "

The Big Bang belongs to the category of theories that try to fully trace the history of the birth of the Universe, to determine the initial, current and final processes in its life.

Was there something before the universe began? This fundamental, almost metaphysical question is being asked by scientists to this day. The emergence and evolution of the universe has always been and remains the subject of heated debate, incredible hypotheses and mutually exclusive theories. The main versions of the origin of everything that surrounds us, according to the church interpretation, assumed divine intervention, and scientific world supported the hypothesis of Aristotle about the static nature of the universe. The latter model was followed by Newton, who defended the infinity and permanence of the Universe, and Kant, who developed this theory in his writings. In 1929, the American astronomer and cosmologist Edwin Hubble radically changed the views of scientists on the world.

He not only discovered the presence of numerous galaxies, but also the expansion of the Universe - a continuous isotropic increase in the size of outer space, which began at the moment of the Big Bang.

To whom do we owe the discovery of the Big Bang?

Albert Einstein's work on the theory of relativity and his gravitational equations allowed de Sitter to create a cosmological model of the universe. Further research was tied to this model. In 1923, Weil suggested that matter placed in outer space should expand. The work of the outstanding mathematician and physicist AA Fridman is of great importance in the development of this theory. Back in 1922, he allowed the expansion of the Universe and made well-founded conclusions that the beginning of all matter was in one infinitely dense point, and the Big Bang gave development to everything. In 1929, Hubble published his articles explaining the subordination of radial velocity to distance, later this work became known as "Hubble's law."

G.A.Gamov, relying on Friedman's theory of the Big Bang, developed the idea of high temperature starting material. He also suggested the presence of cosmic radiation, which did not disappear with the expansion and cooling of the world. The scientist performed preliminary calculations of the possible temperature of the residual radiation. Their estimated value was in the range of 1-10 K. By 1950, Gamow made more accurate calculations and announced the result at 3 K. In 1964, radio astronomers from America, while improving the antenna, by eliminating all possible signals, determined the parameters of cosmic radiation. Its temperature turned out to be 3 K. This information became the most important confirmation of Gamow's work and the existence of relic radiation. Subsequent measurements of the cosmic background, carried out in open space, finally proved the accuracy of the scientist's calculations. You can get acquainted with the relic radiation map by.

Modern understanding of the Big Bang theory: how did it happen?

One of the models that comprehensively explain the appearance and development of the universe known to us is the Big Bang theory. According to the version widely accepted today, there was originally a cosmological singularity - a state with infinite density and temperature. Physicists have developed a theoretical basis for the birth of the Universe from a point that had an extreme degree of density and temperature. After the outbreak of the Big Bang, the space and matter of the Cosmos began an incessant process of expansion and stable cooling. According to recent studies, the beginning of the universe was laid at least 13.7 billion years ago.

Initial periods in the formation of the Universe

The first moment, the reconstruction of which is allowed by physical theories, is the Planck era, the formation of which became possible 10-43 seconds after the Big Bang. The temperature of the matter reached 10 * 32 K, and its density was 10 * 93 g / cm3. During this period, gravity gained independence, separating from the fundamental interactions. The incessant expansion and decrease in temperature caused a phase transition of elementary particles.

The next period, characterized by the exponential expansion of the Universe, came in another 10-35 seconds. It was called "Cosmic inflation". An abrupt expansion took place, many times exceeding the usual one. This period gave an answer to the question why the temperature at different points of the Universe is the same? After the Big Bang, the matter did not immediately scatter across the Universe, for another 10-35 seconds it was quite compact and thermal equilibrium was established in it, which was not violated during inflationary expansion. The period gave the basic material - quark-gluon plasma, which was used to form protons and neutrons. This process took place after a further decrease in temperature, it is called "baryogenesis". The origin of matter was accompanied by the simultaneous emergence of antimatter. Two antagonistic substances annihilated, becoming radiation, but the number of ordinary particles prevailed, which allowed the emergence of the universe.

The next phase transition, which occurred after the temperature decreased, led to the appearance of elementary particles known to us. The era of "nucleosynthesis" that came after this was marked by the union of protons into light isotopes. The first nuclei formed had a short life span; they disintegrated during inevitable collisions with other particles. More stable elements arose after three minutes after the creation of the world.

The next significant milestone was the dominance of gravity over other available forces. After 380 thousand years from the time of the Big Bang, the hydrogen atom appeared. The increase in the influence of gravity served as the end of the initial period of the formation of the Universe and gave rise to the process of the emergence of the first stellar systems.

Even after almost 14 billion years, relic radiation is still preserved in space. Its existence in combination with redshift is presented as an argument in support of the consistency of the Big Bang theory.

Cosmological singularity

If, using the general theory of relativity and the fact of the continuous expansion of the Universe, we return to the beginning of time, then the dimensions of the universe will be equal to zero. The starting point or science cannot accurately describe using physical knowledge. The applied equations are not suitable for such a small object. A symbiosis is needed that can combine quantum mechanics and general relativity, but, unfortunately, it has not yet been created.

The evolution of the Universe: what awaits it in the future?

Scientists are considering two possible options for the development of events: the expansion of the Universe will never end, or it will reach a critical point and begin reverse process- compression. This fundamental choice depends on the value of the average density of the substance in its composition. If the calculated value is less than the critical value, the forecast is favorable; if it is greater, then the world will return to the singular state. Scientists currently do not know the exact value of the described parameter, so the question of the future of the Universe is hanging in the air.

Religion's relationship to the Big Bang theory

The main religions of mankind: Catholicism, Orthodoxy, Islam, in their own way support this model of the creation of the world. Liberal representatives of these religious denominations agree with the theory of the emergence of the universe as a result of some inexplicable interference, defined as the Big Bang.

The name of the theory, familiar to the whole world - "Big Bang" - was unwittingly presented by the adversary to the version of the expansion of the Universe by Hoyle. He considered this idea "completely unsatisfactory." After the publication of his thematic lectures, the amusing term was immediately picked up by the public.

The reasons for the Big Bang are not known for certain. According to one of the numerous versions, belonging to A. Yu. Glushko, the original matter compressed into a point was a black hyper-hole, and the cause of the explosion was the contact of two such objects, consisting of particles and antiparticles. During annihilation, the matter partially survived and gave rise to our Universe.

The engineers Penzias and Wilson, who discovered the cosmic microwave background radiation from the Universe, received the Nobel Prizes in physics.

The temperature of the background radiation was initially very high. Several million years later, this parameter turned out to be within the limits ensuring the origin of life. But by this period, only a small number of planets had managed to form.

Astronomical observations and research help to find answers to the most important questions for mankind: "How did everything appear, and what awaits us in the future?" Despite the fact that not all problems have been solved, and the root cause of the appearance of the Universe does not have a strict and orderly explanation, the Big Bang theory has found a sufficient number of confirmations that make it the main and acceptable model for the emergence of the universe.

Our Galaxy - the Milky Way - belongs to the so-called spiral type Galaxies (S - Galaxies), which are a rotating disk of hydrogen gas, dust and stars with pronounced spiral arms (Fig. 1.6). This is a complex astronomical object, consisting of a core - a thickening in the central part - a bulge (from the English word “buldge”), a halo and the disk itself (Fig. 1.7). The dense core in the center of the disk contains mostly old stars and contains no gas or dust. At the heart of our Galaxy is black hole ( Black holes are beautifully described in the book by A.M. Turtle "Black holes").
Recently, the orbiting X-ray observatory Chandra recorded a powerful X-ray flare in the center of the Galaxy, which made it possible to determine the size of the black hole - no more than the distance from the Earth to the Sun.
The disk of the Galaxy is filled with gas, dust and, mainly, young stars. The diameter of the disk is about 30,000 parsecs (Pc), the bulge is 8,000 Pc. Almost all stars and most of the gas-dusty matter are concentrated in the spiral arms of the disk.
The disk is surrounded by a spherical halo. Its size is an order of magnitude larger than the transverse size of the disk. The halo contains rare stars and star clusters - clusters numbering many hundreds of thousands of stars. In addition, the Halo has dark matter(“Dark matter”), which was identified by gravitational effects. Dark matter increases the mass of the Galaxy at least several times.
The Sun, the closest star to us, is located in the Orion spiral at a distance of ~ 25000 Pc from the center of our galaxy. The sun is a relatively young star - 5 billion years old. The Milky Way is at least twice as old as the Sun: star clusters may be 10 billion years old.
The total number of stars in the disk of the Galaxy is 10 11 (one hundred billion). In addition to the stars, the Galaxy also includes the interstellar medium. The main component of the interstellar medium is interstellar gas, which consists mainly (~ 90%) of hydrogen and interstellar dust (~ 1%). In the interstellar medium, magnetic fields electromagnetic radiation... The galaxy rotates differentially: at the periphery, its rotation speed is less than in the central regions. The period of our Solar system around the center of the Galaxy is approximately 200 million years. Let's remember this figure. We'll come back to it later.
The average density of interstellar matter in the disk is estimated as 10 -24 g / cm 3 (roughly - 1 hydrogen atom per cm 3). There are large deviations from this value: these are dense clouds up to tens of parsecs with densities from 100 to 1000 atoms / cm 3.
Substance in the Galaxy in an atomic state under the influence of ultraviolet radiation from stars ionizes(neutral atoms “lose” their electronic shells). So, for example, up to 90% of hydrogen is ions- protons.
The mass of the entire Universe, and these are optically bright stars, interstellar dust and gas, molecular clouds, planets, are concentrated in protons and neutrons (85% are protons, and 15% are neutrons). Neutrons, being an unstable particle, exist only inside nuclei. All this constitutes the so-called baryonic matter.

Let us now turn to the problem of quantitative relationships between various forms of matter in the modern Universe. In fig. 1.8 answers this question. The answer is according to the level of our knowledge for today. From the diagram shown in Fig. 1.8, it can be seen that only a few percent (about 4%) of the composition of the Universe refers to what we believe our world is formed from. This is baryonic matter. Everything else, and this is practically 96% - dark matter and dark energy - are still obscure material substances of the Universe for us. We know they definitely exist. But we don't know what it is. We are only building hypotheses and trying to set up experiments in the hope of proving their validity. But the fact remains - we do not yet have arguments in favor of the final choice of the hypothesis explaining the composition of dark matter and dark energy in the Universe.
Dark energy, according to modern views, is exactly the force that makes the universe expand. If the gravity we are accustomed to makes bodies attract each other, then dark energy is rather antigravity, which contributes to the expansion of bodies in the Universe. Apparently, immediately after the Big Bang, the expansion of the Universe took place with a slowdown, but after that “dark energy” overcame gravity and acceleration began again - the expansion of the Universe. This is not a hypothesis, but an experimental fact discovered from radiation redshift - a decrease in the brightness of distant supernovae: they are brighter than they should be from the picture of the slowing down of the expansion of the Universe. The effect of "redshift" - an increase in the wavelength of the spectrum of the observed source registered by the observer (which is why the stars appear brighter) - is one of the remarkable experimental astronomical facts. The cosmological "redshift" of the observed galaxies was predicted by A. Einstein and is still one of the convincing proofs of the expanding Universe.
Plunging into the era of early cosmology, one can recall that it was the great A. Einstein who, trying to preserve the static nature of the Universe, introduced the cosmological constant, which has become historical, - the balancing force of attraction of celestial bodies. But after the discovery of the "redshift", he deleted the constant from his equations. Apparently, A. Einstein was wrong to reject it: After all, this is the dark energy that intrigues modern astrophysicists.
It is not clear whether humanity is lucky or not, but it lives in a period of development of the Universe, when dark energy predominates, contributing to expansion. But this process is probably not eternal, and after a time interval comparable to the age of the Universe (10-20 billion years), history can turn back - our world will begin to shrink. Whether or not the moment of the Big Impact comes - the alternatives to the Big Bang are certainly a big question in modern cosmology.
Scientists have managed to prove the existence of an expanding Universe - this is the redshift of the optical radiation of the Galaxy and relict electromagnetic radiation - relic photons, which will be discussed below. Perhaps scientists will be able to establish in the future the existence of “precursors” of the impending compression of the Universe.
Another experimental fact - the study of the deflection of light from distant galaxies in the gravitational fields of the Universe led astrophysicists to the conclusion about the existence of hidden - dark matter - somewhere near us. It is this dark matter that changes the trajectories of light rays by a greater amount than would be expected in the presence of only visible nearby galaxies. Scientists have studied the distribution on starry sky more than 50,000 galaxies in an attempt to build a spatial model of the structure of dark matter. All the results obtained inexorably testify in favor of its existence, and the Universe is basically dark matter. Modern estimates indicate a value of about 80%. Here we will repeat again - we do not know what particles this dark matter consists of. Scientists only assume that it consists of two parts: so far unknown some exotic massive particles and physical vacuum.
We will come back to this problem, but for now we will turn again to the usual form of matter for us, consisting of baryons (protons and neutrons) and electrons - “baryonic matter”. We know much more about her. Over more than a century of the history of the development of physics - from the discovery of elementary particles and the structure of the atom to the results of research in this area, as well as in astrophysics, science has received at its disposal many new results about the structure of matter familiar to us.

The Big Bang theory has a strong competitor in the current decade - the cyclical theory.

The Big Bang theory is trusted by the absolute majority of scientists studying the early history of our Universe. It really explains a lot and does not contradict the experimental data in any way. Recently, however, it has a rival in the face of a new, cyclical theory, the foundations of which were developed by two extra-class physicists - the director of the Institute of Theoretical Science at Princeton University Paul Steinhardt and the laureate of the Maxwell Medal and the prestigious international TED award Neil Turok, director of the Canadian Institute for Advanced Study in the field of theoretical Physics (Perimeter Institute for Theoretical Physics). With the help of Professor Steinhardt, Popular Mechanics tried to talk about the cyclical theory and the reasons for its appearance.

The title of this article may not sound like a clever joke. According to the generally accepted cosmological concept, the Big Bang theory, our Universe emerged from an extreme state of a physical vacuum generated by a quantum fluctuation. In this state, neither time nor space existed (or they were entangled in space-time foam), and all fundamental physical interactions were fused together. Later they separated and acquired an independent existence - first gravity, then strong interaction, and only then - weak and electromagnetic.

The moment that preceded these changes is usually denoted as zero time, t = 0, but this is pure convention, a tribute to mathematical formalism. According to the standard theory, the continuous flow of time began only after the force of gravity became independent. This moment is usually attributed to the value t = 10 -43 s (more precisely, 5.4x10 -44 s), which is called the Planck time. Modern physical theories are simply not able to meaningfully work with shorter periods of time (it is believed that this requires a quantum theory of gravity, which has not yet been created). In the context of traditional cosmology, it makes no sense to talk about what happened before the initial moment of time, since time in our understanding simply did not exist at that time.

The Big Bang theory is trusted by the absolute majority of scientists studying the early history of our Universe. It really explains a lot and does not contradict the experimental data in any way. Recently, however, it has a rival in the face of a new, cyclical theory, the foundations of which were developed by two extra-class physicists - the director of the Institute of Theoretical Science at Princeton University Paul Steinhardt and the laureate of the Maxwell Medal and the prestigious international TED award Neil Turok, director of the Canadian Institute for Advanced Study in the field of theoretical Physics (Perimeter Institute for Theoretical Physics). With the help of Professor Steinhardt, Popular Mechanics tried to talk about the cyclical theory and the reasons for its appearance.

Inflationary cosmology

An indispensable part of standard cosmological theory is the concept of inflation (see sidebar). After the end of inflation, gravitation came into its own, and the Universe continued to expand, but at a decreasing rate. This evolution stretched over 9 billion years, after which another antigravitational field of a still unknown nature, which is called dark energy, entered into action. It again brought the Universe into a mode of exponential expansion, which seems to be preserved in future times. It should be noted that these conclusions are based on astrophysical discoveries made at the end of the last century, almost 20 years after the appearance of inflationary cosmology.

The inflationary interpretation of the Big Bang was first proposed about 30 years ago and has been refined many times since then. This theory allowed to resolve several fundamental problems that previous cosmology failed to cope with. For example, she explained why we live in a universe with flat Euclidean geometry - in accordance with classical equations Friedman, this is exactly what it should do with exponential expansion. Inflationary theory has explained why cosmic matter has granularity on a scale not exceeding hundreds of millions of light years, and is evenly distributed over long distances. She also gave an interpretation of the failure of any attempts to detect magnetic monopoles, very massive particles with a single magnetic pole, which are believed to have been born in abundance before the onset of inflation (inflation stretched space so much that the initially high density of monopoles was reduced to almost zero, and therefore our instruments cannot detect them).

Soon after the emergence of the inflationary model, several theorists realized that its internal logic did not contradict the idea of ​​permanent multiple birth of more and more new universes. Indeed, quantum fluctuations, such as those that we owe our world to existence, can occur in any quantity if the conditions are right. It is possible that our universe has left the fluctuation zone formed in the predecessor world. In the same way, it can be assumed that sometime and somewhere in our own Universe a fluctuation is formed that "blows out" a young universe of a completely different kind, also capable of cosmological "procreation". There are patterns in which such child universes emerge continuously, branch 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 "nested" in a single space-time continuum, but they are so spaced apart that they do not feel the presence of each other in any way. In general, the concept of inflation allows - moreover, compels! - to believe that in the gigantic megacosmos there are many isolated universes with different arrangements.

Alternative

Theoretical physicists love to come up with alternatives to even the most widely accepted theories. The inflationary model of the Big Bang also has competitors. They did not receive wide support, but they have and have their own followers. The theory of Steinhardt and Turok is not the first among them, and certainly not the last. However, to date, it has been developed in more detail than the others and better explains the observed properties of our world. It has several versions, some of which are based on quantum string theory and multidimensional spaces, while others rely on traditional quantum field theory. The first approach gives more vivid pictures of cosmological processes, so we will dwell on it.

The most advanced version of string theory is known as M-theory. She claims that the physical world has 11 dimensions - ten spatial and one temporal. Spaces of lower dimensions, the so-called branes, float in it. Our universe is just one such brane, with three spatial dimensions. It is filled with various quantum particles (electrons, quarks, photons, etc.), which are actually open vibrating strings with only one spatial dimension - length. The ends of each string are firmly anchored inside a three-dimensional brane, and the string cannot leave the brane. But there are also closed strings that can migrate outside the branes - these are gravitons, quanta of the gravitational field.

How does cyclical theory explain the past and future of the universe? Let's start with the current era. First place now belongs to dark energy, which is causing our universe to expand exponentially, periodically doubling in size. As a result, the density of matter and radiation constantly decreases, the gravitational curvature of space weakens, and its geometry becomes more and more flat. Over the next trillion years, the size of the universe will double about a hundred times and it will turn into an almost empty world, completely devoid of material structures. Next to us is another three-dimensional brane, separated from us by an insignificant distance in the fourth dimension, and it also undergoes a similar exponential expansion and flattening. All this time, the distance between the branes remains practically unchanged.

And then these parallel branes begin to converge. They are pushed towards each other by a force field, the energy of which depends on the distance between the branes. Now the energy density of such a field is positive, so the space of both branes is expanding exponentially - hence, it is this field that provides the effect that is explained by the presence of dark energy! However, this parameter is gradually decreasing and in a trillion years will fall to zero. Both branes will continue to expand anyway, but not exponentially, but at a very slow pace. Consequently, in our world, the density of particles and radiation will remain almost zero, and the geometry will be flat.

New cycle

But the end of the old story is just a prelude to the next cycle. The branes move towards each other and eventually collide. At this stage, the energy density of the interbranch field drops below zero, and it begins to act like gravity (let me remind you that the potential energy of gravity is negative!). When the branes are very close, the inter-brane field begins to amplify quantum fluctuations at every point in our world and transforms them into macroscopic deformations of spatial geometry (for example, in a millionth of a second before the collision, the calculated size of such deformations reaches several meters). After the collision, it is in these zones that the lion's share of the kinetic energy released during the impact is released. As a result, it is there that the most hot plasma with a temperature of about 1023 degrees occurs. It is these regions that become local gravitational nodes and turn into the embryos of future galaxies.

Such a collision replaces the Big Bang of inflationary cosmology. It is very important that all newly formed matter with positive energy appears due to the accumulated negative energy of the interbranch field, therefore the law of conservation of energy is not violated.

Inflationary theory allows for the formation of multiple daughter universes that continually sprout from existing ones.

And how does such a field behave at this decisive moment? Before the collision, the density of its energy reaches a minimum (and negative), then begins to increase, and upon collision it becomes zero. The branes then repel each other and begin to disperse. The density of the interbranch energy undergoes a reverse evolution - again it becomes negative, zero, positive. The brane, enriched with matter and radiation, first expands with a decreasing speed under the braking effect of its own gravitation, and then again goes over to exponential expansion. The new cycle ends like the previous one - and so on ad infinitum. The cycles preceding ours took place in the past - in this model, time is continuous, so the past exists beyond the 13.7 billion years that have passed since the last enrichment of our brane with matter and radiation! Whether they had any beginning at all, the theory is silent.

Cyclic theory explains the properties of our world in a new way. It has a flat geometry, since at the end of each cycle it stretches excessively and only slightly deforms before starting a new cycle. Quantum fluctuations, which become the precursors of galaxies, arise chaotically, but on average evenly - therefore, outer space is filled with clumps of matter, but at very large distances it is quite homogeneous. We cannot detect magnetic monopoles simply because the maximum temperature of the newborn plasma did not exceed 10 23 K, and much higher energies are required for the appearance of such particles - on the order of 10 27 K.

The moment of the Big Bang is the collision of the branes. A huge amount of energy is released, the branes scatter, a slowing expansion occurs, matter and radiation cool down, and galaxies are formed. The expansion is again accelerated due to the positive interbranch energy density, and then it slows down, the geometry becomes flat. Branes are attracted to each other, before the collision, quantum fluctuations are amplified and transform into deformations of spatial geometry, which in the future will become the seeds of galaxies. A collision occurs and the cycle starts over.

A world without beginning or end

The cyclical theory exists in several versions, as does the inflation theory. However, according to Paul Steinhardt, the differences between them are purely technical and interesting only to specialists, the general concept remains unchanged: “First, in our theory there is no moment of the beginning of the world, no singularity. There are periodic phases of intense creation of matter and radiation, each of which, if desired, can be called the Big Bang. But any of these phases does not mark the emergence of a new universe, but only a transition from one cycle to another. Both space and time exist both before and after any of these cataclysms. Therefore, it is quite natural to ask what was the state of affairs 10 billion years before the last Big Bang, from which the history of the universe is counted.

The second key difference is the nature and role of dark energy. Inflationary cosmology did not predict the transition of a decelerating expansion of the Universe to an accelerated one. And when astrophysicists discovered this phenomenon by observing the explosions of distant supernovae, standard cosmology did not even know what to do about it. The hypothesis of dark energy was put forward simply in order to somehow tie the paradoxical results of these observations to the theory. And our approach is much better secured by internal logic, since we have dark energy from the very beginning and it is this energy that ensures the alternation of cosmological cycles. " However, as Paul Steinhardt notes, the cyclic theory also has weak points: “We have not yet been able to convincingly describe the collision and rebound process of parallel branes that takes place at the beginning of each cycle. Other aspects of the cyclical theory are much better developed, and there are still many ambiguities to be cleared. "

Practice check

But even the most beautiful theoretical models need experimental verification. Can cyclic cosmology be confirmed or disproved by observation? “Both inflationary and cyclical theories predict the existence of relic gravitational waves,” explains Paul Steinhardt. - In the first case, they arise from primary quantum fluctuations, which are smeared over space during inflation and generate periodic oscillations of its geometry - and these, according to the general theory of relativity, are gravitational waves. In our scenario, quantum fluctuations are also the root cause of such waves - the same ones that are amplified by collisions of branes. Calculations have shown that each mechanism generates waves with a specific spectrum and specific polarization. These waves were required to leave imprints on cosmic microwave radiation, which is an invaluable source of information about the early cosmos. So far, such traces have not been found, but, most likely, this will be done within the next decade. In addition, physicists are already thinking about the direct registration of relic gravitational waves using spacecraft, which will appear in two to three decades. "

A radical alternative

In the 1980s, Professor Steinhardt made a significant contribution to the development of the standard theory of the Big Bang. However, this did not stop him from looking for a radical alternative to the theory, in which so much work had been invested. As Paul Steinhardt himself told Popular Mechanics, the inflation hypothesis does reveal many cosmological mysteries, but this does not mean that there is no point in looking for other explanations: “At first I was just interested in trying to understand the basic properties of our world without resorting to inflation. Later, when I delved into this issue, I became convinced that the inflationary theory is not at all as perfect as its proponents claim. When inflationary cosmology was just being created, we hoped that it would explain the transition from the original chaotic state of matter to the current ordered Universe. She did just that - but she went a lot further. The internal logic of the theory demanded to admit that inflation constantly creates an infinite number of worlds. This would not be a big deal if their physical device was copying our own, but this just does not work. For example, with the help of the inflationary hypothesis, it was possible to explain why we live in a flat Euclidean world, but after all, most other universes will certainly not have the same geometry. In short, we were building a theory to explain our own world, and it got out of hand and spawned an endless variety of exotic worlds. This state of affairs ceased to suit me. In addition, the standard theory is unable to explain the nature of the earlier state, which preceded the exponential expansion. In this sense, it is as incomplete as the pre-inflationary cosmology. Finally, it is unable to say anything about the nature of dark energy, which has been driving the expansion of our universe for 5 billion years. "

Another difference, according to Professor Steinhardt, is the temperature distribution of the background microwave radiation: “This radiation coming from different parts of the sky is not completely uniform in temperature, it has more and less heated zones. At the level of measurement accuracy provided by modern equipment, the number of hot and cold zones is approximately the same, which coincides with the conclusions of both theories - both inflationary and cyclical. However, these theories predict more subtle differences between zones. In principle, they can be detected by the European space observatory "Planck" launched last year and other newest spacecraft... I hope that the results of these experiments will help to make a choice between inflationary and cyclical theories. But it may also happen that the situation remains uncertain and none of the theories will receive unequivocal experimental support. Well, then I'll have to come up with something new. "

NASA astrophysicists have done important scientific discovery- they experimentally confirmed the inflationary theory of the evolution of the Universe.

Scientists are convinced that they "touched" the events of approximately 14,000,000,000 years ago. In continuation of three years of continuous observations of the cosmic background in the microwave range, they were able to "catch" the light remaining (relict) from the first moments of the life of the Universe. These discoveries were made using the WMAP (Wilkinson Microwave Anisotropy Probe) apparatus.

Astrophysicists study the Universe at the moment of its existence, when its age was about one trillionth of a second, that is, almost immediately after the Big Bang. It was at this moment that the beginnings of future hundreds of millions of galaxies appeared in the tiny Universe, from which stars and planets were formed over hundreds of millions of years.

The leading postulate of inflationary theory is this: after the Big Bang, which gave rise to our Universe, in an incredibly short period of time - a trillionth of a second - it turned from a microscopic object into something colossal, many times larger than the entire observable part of the cosmos, that is, it underwent inflation.

"The results are in favor of inflation," said Charles Bennett (Johns Hopkins University), who announced the discovery. "It's amazing that we can say anything at all about what happened in the first trillionth of a second of the universe's existence," he said.

Apparently, in the first trillionth fractions of a second after the Explosion, the expansion rate of the Universe was higher than the speed of light, and the time that has passed since the expansion of the Universe from the size of several atoms to a stable spherical shape is measured in very small quantities. For the first time this hypothesis was put forward back in the 80s.

"How do we know what was in the Universe at the time of its creation? The cosmic microwave background is a real treasure trove of information about the past of our Universe. The light radiation that has come down to us accurately indicates the facts of the development of the Universe," says Dr. Gary Hinshaw, employee NASA's Goddard Space Center.

The inflationary theory itself exists in several versions, says the astronomer Nikolai Nikolaevich Chugay (Institute of Astronomy of the Russian Academy of Sciences) to NewsInfo.

"There is no complete theory of this, but there are only some assumptions about how it happened. But there is one" prediction "that follows from the fact that quantum fluctuations (from Latin fluctuatio - fluctuation; random deviations physical quantities on their average values ​​on microscopic scales) predict a certain spectrum of disturbances, that is, the distribution of the amplitude of these disturbances depending on the length of the scale on which this disturbance develops. You can imagine a wavy line with different wavelengths in the figure, and if you have one amplitude for large-scale and another for small-scale, you say that the spectrum of these disturbances is not flat, "explains Nikolai Chugai.

Until about the 1970s, there was a standard Big Bang picture, according to which our universe emerged from a very dense, hot state. The thermonuclear fusion of helium has taken place - this is one of the confirmations of the hot Universe model. In 1964, relict (residual) radiation was discovered, for which the Nobel Prize was received. The relic radiation comes to us from very distant regions. In the process of expansion, the radiation filling the big universe, cools down.

"This property is similar to when a balloon bursts and becomes cold," Nikolay Chugay explains.

"The detection of this radiation (it is now cold - only 3 degrees) was decisive evidence of the hot phase of the Universe. But this model is not complete, - the astronomer believes. - It does not explain everything. And the main thing is that it does not explain the fact that the Universe is homogeneous. Wherever we look - we see almost the same galaxies with the same density of these galaxies in units of volume. Everywhere it is approximately the same structure. Since these distant points of the Universe do not interact, it turns out strange - from the point of view of physics - how are they do not interact and do not know anything about each other, relatively speaking? And, nevertheless, the Universe is arranged in these distant points in the same way. And this should mean for a physicist that once these distant parts of the Universe were in contact. That is, they were part of a whole in which the disturbances spread and these disturbances smoothed out. That is, once the universe that we see now on a large scale was physically one ala and disturbances from these distant points had time to pass and smear the disturbances that arose there. "

Today we just observe this homogeneity in distant points of the Universe in opposite regions of the sky as completely identical in density - relic radiation, which we observe with absolutely the same intensity and brightness. "No matter where you look," says Dr. Chugay.

"And this means that the Universe was absolutely homogeneous - isotropic. This initial inflationary stage makes it possible to" prepare "such a homogeneous universe. Another advantage of the inflationary phase is not only that it prepared a homogeneous universe, but also that the so-called quantum fluctuations (density perturbations on microscopic length scales) were associated with the quantum nature of our world (at the level of elementary particles), "concluded Nikolai Chugai.

Hear the sounds of a simulated Big Bang.

The article used materials:

2.Ringside Seat to the Universe "s First Split Second 3.Russian media