Who invented the big bang theory? What do fans of The Big Bang Theory prefer not to notice? Advances in inflation theory

Everyone has heard of the Big Bang theory, which explains (at least for now) the origin of our Universe. However, in scientific circles there will always be those who want to challenge ideas - from this, by the way, great discoveries often arise.

However, Dicke realized that if this model were real, then there would not be two types of stars - Population I and Population II, young and old stars. And they were. This means that the Universe around us nevertheless developed from a hot and dense state. Even if it was not the only Big Bang in history.

Amazing, right? What if there were several of these explosions? Tens, hundreds? Science has yet to figure this out. Dicke invited his colleague Peebles to calculate the temperature required for the processes described and the probable temperature of the residual radiation today. Peebles' rough calculations showed that today the Universe should be filled with microwave radiation with a temperature of less than 10 K, and Roll and Wilkinson were already preparing to look for this radiation when the bell rang...

Lost in translation

However, here it is worth moving to another corner of the globe - to the USSR. The closest people to the discovery of cosmic microwave background radiation (and also did not complete the job!) were in the USSR. Having done a huge amount of work over the course of several months, a report on which was published in 1964, Soviet scientists seemed to have put together all the pieces of the puzzle, only one was missing. Yakov Borisovich Zeldovich, one of the colossi of Soviet science, carried out calculations similar to those carried out by the team of Gamow (a Soviet physicist living in the USA), and also came to the conclusion that the Universe must have begun with a hot Big Bang, which left background radiation with a temperature a few kelvins.

Yakov Borisovich Zeldovich, -

He even knew about Ed Ohm's article in the Bell System Technical Journal, which roughly calculated the temperature of the cosmic microwave background radiation, but misinterpreted the author's conclusions. Why didn't Soviet researchers realize that Ohm had already discovered this radiation? Due to an error in translation. Ohm's paper stated that the sky temperature he measured was about 3 K. This meant that he had subtracted all possible sources of radio interference and that 3 K was the temperature of the remaining background.

However, by coincidence, the temperature of atmospheric radiation was also the same (3 K), for which Ohm also made a correction. Soviet specialists mistakenly decided that it was these 3 K that Ohm had left after all the previous adjustments, subtracted them too and were left with nothing.

Nowadays, such misunderstandings would be easily corrected through electronic correspondence, but in the early 1960s, communication between scientists in the Soviet Union and the United States was very difficult. This was the reason for such an offensive mistake.

The Nobel Prize that floated away

Let's go back to the day when the phone rang in Dicke's laboratory. It turns out that at the same time, astronomers Arno Penzias and Robert Wilson reported that they accidentally managed to detect faint radio noise coming from everything. Then they did not yet know that another team of scientists independently came up with the idea of ​​​​the existence of such radiation and even began to build a detector to search for it. It was the team of Dicke and Peebles.

Even more surprising is that the cosmic microwave background, or, as it is also called, cosmic microwave background radiation, was described more than ten years earlier within the framework of the model of the emergence of the Universe as a result of the Big Bang by George Gamow and his colleagues. Neither one nor the other group of scientists knew about this.

Penzias and Wilson accidentally learned about the work of scientists under Dicke's leadership and decided to call them to discuss it. Dicke listened carefully to Penzias and made several comments. After hanging up, he turned to his colleagues and said: “Guys, we got ahead of ourselves.”

Nearly 15 years later, after many measurements made at a variety of wavelengths by many groups of astronomers confirmed that the radiation they discovered was indeed a relic echo of the Big Bang, having a temperature of 2.712 K, Penzias and Wilson shared the Nobel Prize for their invention. Although at first they did not even want to write an article about their discovery, because they considered it untenable and did not fit into the model of a stationary Universe that they adhered to!

It is said that Penzias and Wilson would have considered it sufficient to be mentioned as the fifth and sixth names on the list after Dicke, Peebles, Roll and Wilkinson. In this case, the Nobel Prize would apparently go to Dicke. But everything happened the way it happened.

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The Big Bang theory is now considered as certain as the Copernican system. However, until the second half of the 1960s, it did not enjoy universal recognition, and not only because many scientists initially denied the very idea of ​​​​the expansion of the Universe. It’s just that this model had a serious competitor.

In 11 years, cosmology as a science will be able to celebrate its centenary. In 1917, Albert Einstein realized that the equations of general relativity made it possible to calculate physically reasonable models of the universe. Classical mechanics and the theory of gravity do not provide such a possibility: Newton tried to build a general picture of the Universe, but in all scenarios it inevitably collapsed under the influence of gravity.

Einstein absolutely did not believe in the beginning and end of the universe and therefore came up with an eternally existing static Universe. To do this, he needed to introduce a special component into his equations, which created “anti-gravity” and thereby formally ensured the stability of the world order. Einstein considered this addition (the so-called cosmological term) inelegant, ugly, but still necessary (the author of General Relativity did not trust his aesthetic instinct in vain - it was later proven that the static model is unstable and therefore physically meaningless).

Einstein's model quickly had competitors - the model of a world without matter by Willem de Sitter (1917), closed and open non-stationary models of Alexander Friedman (1922 and 1924). But these beautiful constructions for the time being remained purely mathematical exercises. In order to talk about the Universe as a whole not speculatively, one must at least know that there are worlds located outside the star cluster in which the Solar system and we are located along with it. And cosmology received the opportunity to seek support in astronomical observations only after Edwin Hubble published his work “Extragalactic Nebulae” in 1926, where galaxies were first described as independent star systems not part of the Milky Way.

The creation of the Universe did not take six days - the bulk of the work was completed much earlier. Here is his approximate chronology.

0. Big Bang.

Planck era: 10-43 s. Planck moment. Gravitational interaction is separated. The size of the Universe at this moment is 10-35 m (the so-called Planck length). 10-37 s. Inflationary expansion of the Universe.

The era of great unification: 10-35 pp. Separation of strong and electroweak interactions. 10-12 s. Separation of weak interactions and final separation of interactions.

Hadron era: 10-6 s. Annihilation of proton-antiproton pairs. Quarks and antiquarks cease to exist as free particles.

Lepton era: 1 s. Hydrogen nuclei are formed. Nuclear fusion of helium begins.

Era of Nucleosynthesis: 3 minutes. The universe is made up of 75% hydrogen and 25% helium, as well as trace amounts of heavy elements.

Radiation era: 1 week. By this time the radiation is thermalized.

The era of matter: 10 thousand years. Matter begins to dominate the Universe. 380 thousand years. Hydrogen nuclei and electrons recombine, the Universe becomes transparent to radiation.

Stellar era: 1 billion years. Formation of the first galaxies. 1 billion years. Formation of the first stars. 9 billion years. Formation of the Solar System. 13.5 billion years. This moment

Retreat of galaxies

This chance was quickly realized. The Belgian Georges Henri Lemaître, who studied astrophysics at the Massachusetts Institute of Technology, heard rumors that Hubble was close to a revolutionary discovery - proof of the recession of galaxies. In 1927, having returned to his homeland, Lemaitre published (and in subsequent years refined and developed) a model of the Universe formed as a result of an explosion of superdense matter expanding in accordance with the equations of general relativity. He mathematically proved that their radial speed should be proportional to their distance from the Solar System. A year later, Princeton mathematician Howard Robertson independently came to the same conclusion.

And in 1929, Hubble obtained the same dependence experimentally by processing data on the distance of twenty-four galaxies and the redshift of the light coming from them. Five years later, Hubble and his observing assistant Milton Humason provided further evidence of this conclusion by monitoring very faint galaxies that lie on the extreme periphery of observable space. The predictions of Lemaître and Robertson were completely justified, and the cosmology of the nonstationary Universe seemed to have won a decisive victory.

Unrecognized model

But still, astronomers were in no hurry to shout hurray. Lemaitre's model made it possible to estimate the duration of the existence of the Universe - for this it was only necessary to find out the numerical value of the constant included in the Hubble equation. Attempts to determine this constant led to the conclusion that our world arose only about two billion years ago. However, geologists argued that the Earth was much older, and astronomers had no doubt that space was full of stars of a more respectable age. Astrophysicists also had their own reasons for mistrust: the percentage composition of the distribution of chemical elements in the Universe based on the Lemetre model (this work was first done by Chandrasekhar in 1942) clearly contradicted reality.

The skepticism of specialists was also explained by philosophical reasons. The astronomical community has just gotten used to the idea that an endless world populated by many galaxies has opened up before it. It seemed natural that in its fundamentals it does not change and exists forever. And now scientists were asked to admit that the Cosmos is finite not only in space, but also in time (moreover, this idea suggested divine creation). Therefore, Lemetre's theory remained out of work for a long time. However, an even worse fate befell the model of an eternally oscillating Universe, proposed in 1934 by Richard Tolman. It did not receive serious recognition at all, and in the late 1960s it was rejected as mathematically incorrect.

Stocks of the "bloat world" did not rise much after George Gamow and his graduate student Ralph Alpher built a new, more realistic version of this model in early 1948. Lemaître's universe was born from the explosion of a hypothetical "primary atom", which clearly went beyond the ideas of physicists about the nature of the microcosm.

For a long time, Gamow's theory was called quite academically - the “dynamic evolving model.” And the phrase “Big Bang,” oddly enough, was not coined by the author of this theory or even its supporter. In 1949, BBC science producer Peter Laslett invited Fred Hoyle to prepare a series of five lectures. Hoyle shone in front of the microphone and instantly gained a huge following among radio listeners. In his last speech, he talked about cosmology, talked about his model, and in the end decided to settle scores with his competitors. Their theory, Hoyle said, "is based on the assumption that the universe came into existence in a single powerful explosion and therefore exists only for a finite time... This Big Bang idea seems to me completely unsatisfactory." This is how this expression first appeared. It can also be translated into Russian as “Big Cotton,” which probably more accurately corresponds to the derogatory meaning that Hoyle put into it. A year later, his lectures were published, and the new term went around the world

George Gamow and Ralph Alpher proposed that the Universe, shortly after its birth, consisted of the well-known particles - electrons, photons, protons and neutrons. In their model, this mixture was heated to high temperatures and tightly packed into a tiny (compared to today's) volume. Gamow and Alfer showed that thermonuclear fusion occurs in this super-hot soup, resulting in the formation of the main isotope of helium, helium-4. They even calculated that after just a few minutes, matter goes into an equilibrium state, in which for every helium nucleus there are about a dozen hydrogen nuclei.

This proportion was quite consistent with astronomical data on the distribution of light elements in the Universe. These findings were soon confirmed by Enrico Fermi and Anthony Turkiewicz. They also established that thermonuclear fusion processes must produce some light isotope helium-3 and heavy isotopes of hydrogen - deuterium and tritium. Their estimates of the concentrations of these three isotopes in outer space also coincided with the observations of astronomers.

Problem theory

But practicing astronomers continued to doubt. Firstly, there remained the problem of the age of the Universe, which Gamow’s theory could not solve. It was possible to increase the duration of the world's existence only by proving that galaxies fly away much more slowly than is commonly believed (eventually this happened, and to a large extent with the help of observations made at the Palomar Observatory, but already in the 1960s).

Secondly, Gam's theory stalled on nucleosynthesis. Having explained the emergence of helium, deuterium and tritium, she was unable to advance to heavier nuclei. The helium-4 nucleus consists of two protons and two neutrons. Everything would be fine if it could attach a proton and turn into a lithium nucleus. However, nuclei of three protons and two neutrons or two protons and three neutrons (lithium-5 and helium-5) are extremely unstable and decay instantly. Therefore, only stable lithium-6 (three protons and three neutrons) exists in nature. For its formation by direct fusion, it is necessary that both a proton and a neutron simultaneously merge with a helium nucleus, and the probability of this event is extremely low. True, under conditions of high matter density in the first minutes of the existence of the Universe, such reactions still occasionally occur, which explains the very low concentration of the oldest lithium atoms.

Nature prepared another unpleasant surprise for Gamow. The path to heavy elements could also lie through the fusion of two helium nuclei, but this combination is also unviable. There was no way to explain the origin of elements heavier than lithium, and in the late 1940s this obstacle seemed insurmountable (we now know that they are born only in stable and exploding stars and in cosmic rays, but Gamow did not know this).

However, the model of the “hot” birth of the Universe still had one more card in reserve, which over time became a trump card. In 1948, Alpher and another of Gamow's assistants, Robert Herman, came to the conclusion that space was permeated by microwave radiation that arose 300 thousand years after the primary cataclysm. However, radio astronomers showed no interest in this forecast, and it remained on paper.

The emergence of a competitor

Gamow and Alpher invented their “hot” model in the US capital, where Gamow taught at George Washington University since 1934. Many of their productive ideas arose over moderate drinks at the Little Vienna bar on Pennsylvania Avenue near the White House. And if this path to the construction of a cosmological theory seems exotic to some, what can be said about the alternative that was born under the influence of a horror film?

Fred Hoyle: The Universe is expanding forever! Matter is born spontaneously in emptiness at such a speed that the average density of the Universe remains constant

In good old England, at the University of Cambridge, three remarkable scientists settled after the war - Fred Hoyle, Herman Bondi and Thomas Gold. Before that, they worked in the radar laboratory of the British Navy, where they became friends. Hoyle, an Englishman from Yorkshire, was not yet 30 at the time of Germany’s surrender, and his friends, natives of Vienna, were 25. Hoyle and his friends in their “radar era” devoted themselves to conversations about the problems of the universe and cosmology. All three disliked Lemaitre's model, but they took Hubble's law seriously, and therefore rejected the concept of a static Universe. After the war they gathered at Bondi's and discussed the same problems. The inspiration came after watching the horror movie “Dead in the Night”. Its main character, Walter Craig, found himself in a closed loop of events, which at the end of the film returned him to the same situation with which it all began. A film with such a plot can last forever (like a poem about a priest and his dog). It was then that Gold realized that the Universe could turn out to be an analogue of this plot - simultaneously changing and unchanging!

Friends thought the idea was crazy, but then decided that there was something in it. Together they turned the hypothesis into a coherent theory. Bondi and Gold gave a general presentation of it, and Hoyle, in a separate publication, “A New Model of the Expanding Universe,” gave mathematical calculations. He took the general relativity equations as a basis, but supplemented them with a hypothetical “Creation field” (C-field), which has negative pressure. Something of this kind appeared 30 years later in inflationary cosmological theories, which Hoyle emphasized with considerable pleasure.

Steady State Cosmology

The new model entered the history of science as Steady State Cosmology. She proclaimed complete equality not only of all points of space (this was the case with Einstein), but also of all moments of time: the Universe is expanding, but has no beginning, since it always remains similar to itself. Gold called this statement the perfect cosmological principle. The geometry of space in this model remains flat, just like Newton's. Galaxies scatter, but in space “out of nothing” (more precisely, from the field of creation) new matter appears, and with such intensity that the average density of matter remains unchanged. In accordance with the then-known value of the Hubble constant, Hoyle calculated that only one particle is born in every cubic meter of space over the course of 300 thousand years. The question immediately disappeared as to why the instruments do not register these processes - they are too slow by human standards. The new cosmology did not experience any difficulties associated with the age of the Universe; this problem simply did not exist for it.

To confirm his model, Hoyle proposed using data on the spatial distribution of young galaxies. If the C-field uniformly creates matter everywhere, then the average density of such galaxies should be approximately the same. On the contrary, the model of the cataclysmic birth of the Universe predicts that at the far edge of observable space this density is maximum - from there the light of star clusters that have not yet had time to grow old comes to us. Hoyle's criterion was completely reasonable, but at that time it was not possible to test it due to the lack of sufficiently powerful telescopes.

Triumph and defeat

For more than 15 years, rival theories fought almost as equals. True, in 1955, the English radio astronomer and future Nobel laureate Martin Ryle discovered that the density of weak radio sources on the cosmic periphery is greater than near our galaxy. He stated that these results are inconsistent with Steady State Cosmology. However, a few years later his colleagues concluded that Ryle had exaggerated the differences in densities, so the question remained open.

But in his twentieth year, Hoyle's cosmology began to quickly fade. By this time, astronomers had proven that the Hubble constant was an order of magnitude smaller than previous estimates, which made it possible to raise the estimated age of the Universe to 10-20 billion years (the modern estimate is 13.7 billion years ± 200 million). And in 1965, Arno Penzias and Robert Wilson detected the radiation predicted by Alpher and Herman and thereby immediately attracted a great many supporters to the Big Bang theory.

For forty years now, this theory has been considered the standard and generally accepted cosmological model. It also has competitors of different ages, but no one takes Hoyle’s theory seriously anymore. Even the discovery (in 1999) of accelerating the expansion of galaxies, the possibility of which both Hoyle and Bondi and Gold wrote about, did not help her. Her time is irrevocably gone.

Even modern scientists cannot say with certainty what was in the Universe before the Big Bang. There are several hypotheses that lift the veil of secrecy over one of the most complex issues of the universe.

Origin of the material world

Until the 20th century, there were only two supporters of the religious point of view, who believed that the world was created by God. Scientists, on the contrary, refused to acknowledge the man-made nature of the Universe. Physicists and astronomers were supporters of the idea that space has always existed, the world was static and everything will remain the same as billions of years ago.

However, accelerated scientific progress at the turn of the century led to the fact that researchers had opportunities to study extraterrestrial spaces. Some of them were the first to try to answer the question of what was in the Universe before the Big Bang.

Hubble Research

The 20th century destroyed many theories of past eras. In the vacated space, new hypotheses appeared that explained hitherto incomprehensible mysteries. It all started with the fact that scientists established the fact of the expansion of the Universe. This was done by Edwin Hubble. He discovered that distant galaxies differed in their light from those cosmic clusters that were closer to Earth. The discovery of this pattern formed the basis of Edwin Hubble's law of expansion.

The Big Bang and the origin of the Universe were studied when it became clear that all galaxies “escape” from the observer, no matter where he was. How could this be explained? Since galaxies move, it means that they are pushed forward by some kind of energy. In addition, physicists have calculated that all worlds were once located at one point. Due to some push, they began to move in all directions with unimaginable speed.

This phenomenon was called the “Big Bang”. And the origin of the Universe was explained precisely with the help of the theory of this ancient event. When did it happen? Physicists determined the speed of movement of galaxies and derived a formula that they used to calculate when the initial “push” occurred. No one can give exact numbers, but approximately this phenomenon took place about 15 billion years ago.

The emergence of the Big Bang theory

The fact that all galaxies are sources of light means that the Big Bang released a huge amount of energy. It was she who gave birth to the very brightness that the worlds lose as they move away from the epicenter of what happened. The Big Bang theory was first proven by American astronomers Robert Wilson and Arno Penzias. They discovered electromagnetic cosmic microwave background radiation, the temperature of which was three degrees on the Kelvin scale (that is, -270 Celsius). This find supported the idea that the Universe was initially extremely hot.

The Big Bang theory answered many questions formulated in the 19th century. However, now new ones have appeared. For example, what was in the Universe before the Big Bang? Why is it so homogeneous, while with such a huge release of energy the substance should scatter unevenly in all directions? The discoveries of Wilson and Arno cast doubt on classical Euclidean geometry, as it was proven that space has zero curvature.

Inflationary theory

New questions posed showed that the modern theory of the origin of the world is fragmentary and incomplete. However, for a long time it seemed that it would be impossible to advance beyond what was discovered in the 60s. And only very recent research by scientists has made it possible to formulate a new important principle for theoretical physics. This was the phenomenon of ultra-fast inflationary expansion of the Universe. It was studied and described using quantum field theory and Einstein's general theory of relativity.

So what was in the Universe before the Big Bang? Modern science calls this period “inflation.” In the beginning there was only a field that filled all imaginary space. It can be compared to a snowball thrown down the slope of a snowy mountain. The lump will roll down and increase in size. In the same way, the field, due to random fluctuations, changed its structure over an unimaginable time.

When a homogeneous configuration was formed, a reaction occurred. It contains the biggest mysteries of the Universe. What happened before the Big Bang? An inflationary field that was not at all like current matter. After the reaction, the growth of the Universe began. If we continue the analogy with a snowball, then after the first one, other snowballs rolled down, also increasing in size. The moment of the Big Bang in this system can be compared to the second when a huge block fell into the abyss and finally collided with the ground. At that moment, a colossal amount of energy was released. It still can't run out. It is due to the continuation of the reaction from the explosion that our Universe is growing today.

Matter and field

The Universe now consists of an unimaginable number of stars and other cosmic bodies. This aggregate of matter exudes enormous energy, which contradicts the physical law of conservation of energy. What does it say? The essence of this principle comes down to the fact that over an infinite period of time the amount of energy in the system remains unchanged. But how can this fit in with our Universe, which continues to expand?

Inflationary theory was able to answer this question. It is extremely rare that such mysteries of the Universe are solved. What happened before the Big Bang? Inflationary field. After the emergence of the world, matter familiar to us took its place. However, in addition to it, there is also something in the Universe that has negative energy. The properties of these two entities are opposite. This compensates for the energy coming from particles, stars, planets and other matter. This relationship also explains why the Universe has not yet turned into a black hole.

When the Big Bang first happened, the world was too small for anything to collapse. Now, when the Universe has expanded, local black holes have appeared in certain parts of it. Their gravitational field absorbs everything around them. Not even light can get out of it. This is actually why such holes become black.

Expansion of the Universe

Even despite the theoretical justification of the inflationary theory, it is still unclear what the Universe looked like before the Big Bang. The human imagination cannot imagine this picture. The fact is that the inflation field is intangible. It cannot be explained by the usual laws of physics.

When the Big Bang occurred, the inflation field began to expand at a rate that exceeded the speed of light. According to physical indicators, there is nothing material in the Universe that could move faster than this indicator. Light spreads across the existing world with incredible numbers. The inflationary field spread with even greater speed, precisely due to its intangible nature.

Current State of the Universe

The current period in the evolution of the Universe is ideally suited for the existence of life. Scientists find it difficult to determine how long this time period will last. But if anyone undertook such calculations, the resulting figures were no less than hundreds of billions of years. For one human life, such a segment is so large that even in mathematical calculus it has to be written down using powers. The present has been studied much better than the prehistory of the Universe. What happened before the Big Bang will, in any case, remain only the subject of theoretical research and bold calculations.

In the material world, even time remains a relative value. For example, quasars (a type of astronomical object), existing at a distance of 14 billion light years from Earth, are 14 billion light years behind our usual “now”. This time gap is enormous. It is difficult to define even mathematically, not to mention the fact that it is simply impossible to clearly imagine such a thing with the help of human imagination (even the most ardent).

Modern science can theoretically explain the entire life of our material world, starting from the first fractions of seconds of its existence, when the Big Bang just occurred. The complete history of the Universe is still being updated. Astronomers are discovering amazing new facts with the help of modernized and improved research equipment (telescopes, laboratories, etc.).

However, there are also phenomena that are still not understood. Such a white spot, for example, is its dark energy. The essence of this hidden mass continues to excite the consciousness of the most educated and advanced physicists of our time. In addition, no single point of view has emerged about the reasons why there are still more particles in the Universe than antiparticles. Several fundamental theories have been formulated on this matter. Some of these models are the most popular, but none of them has yet been accepted by the international scientific community as

On the scale of universal knowledge and colossal discoveries of the 20th century, these gaps seem quite insignificant. But the history of science shows with enviable regularity that the explanation of such “small” facts and phenomena becomes the basis for humanity’s entire understanding of the discipline as a whole (in this case we are talking about astronomy). Therefore, future generations of scientists will certainly have something to do and something to discover in the field of knowledge of the nature of the Universe.

Most astronomers support the idea that the universe originated from a “bubble” thousands of times smaller than the head of a pin, but incredibly hot and dense. Almost 13.8 billion years ago it exploded, and this event is called the “Big Bang”. At that moment, space, time, energy and matter began to exist. In a very short period of time, the Universe expanded from the size of a subatomic particle to the size of an orange, and then continued to expand, gradually acquiring its modern appearance. It is the Big Bang that explains the various parameters of the Universe we know today, and it was the Big Bang that determined how it will develop in the future and perhaps die billions and billions of years from now. The study of the Big Bang is a search for an answer to the question of what the beginning of “everything” was and what its end will be.

First moments

Astrophysicists wonder what was at the beginning of the Universe and what was before its beginning. Thanks to physical and mathematical research, some answers to such questions have already been obtained. But answers that satisfy theoretical physicists are not always understandable to the general public and transferable to our everyday reality. In other words, a number of concepts should be accepted “by definition” without trying to find empirical examples in today's Universe that would allow us to understand what happened in the first moments after the Big Bang.

Start

At the beginning of time and space, it is likely that there was a “gravitational singularity,” that is, what we can define as a geometric point at which the gravitational field reached an infinitely large magnitude. Gravitational singularities, the existence of which is provided for by Albert Einstein's general theory of relativity, form when the density of matter is so high that it causes the collapse of space-time. The singularity is very difficult to imagine as something concrete; it can be described mainly through mathematical concepts. Having suggested that the universe was born from the Big Bang, some researchers have wondered whether there was something before it. The problem is complicated by the fact that the Big Bang gave rise not only to space, but also to time itself, so that in the general theory of relativity we are talking about “space-time” as a single whole. This leads us to the idea that the Big Bang did not occur in “empty space”, which was subsequently filled by the expanding Universe, but itself created both space and time.

Planck era

What appeared immediately after the Big Bang had such pressure and temperature that its behavior cannot be described using the laws operating in the modern Universe. The phase immediately following the Big Bang is called the “Planck era” after the German scientist Max Planck. It covers the period from the Big Bang to the time 10 × -43 degrees s after it (this time is called “Planck time”). During this very short period, the Universe reached a size of 10 × - 33 degrees cm, and the temperature dropped to 10 × 32 degrees ° C, that is, to one hundred thousand billion billion billion degrees.

The smallest space

In order to define this phase, Planck made a relatively simple conclusion. He asked himself whether there was a minimum wavelength below which no information could be obtained, that is, a minimum value below which the concept of space became meaningless.

Since gamma rays have the shortest electromagnetic wavelength (it is 10 × -33 degrees cm), Planck guessed that for shorter wavelengths there was no way to obtain complete physical information. A gamma ray traveling at the speed of light travels in 10 × -43 degrees s. a distance of 10 × -33 degrees cm. Shorter periods of time are beyond the scope of measurement. Therefore, between the zero point of the Big Bang and the end of the Planck era, no physical information about the Universe at the first stage of development can be obtained.

Soon after the Big Bang

At the end of the Planck era, the force of gravity separated from the total energy available in the Universe and became independent. Immediately after this came the turn of the strong nuclear force (which holds atomic nuclei in a stable state), which, together with the forces of gravity, electromagnetic force and the weak force (the latter responsible for radioactive decay), is one of the four fundamental forces present in nature. With their help, particles exchange energy. All this since the Big Bang took up to 10 × -36 degrees of s.

Inflation

At this point, the “era of inflation” began. It is called so because at this stage the Universe underwent a very rapid expansion - “inflation” (from English to inflate - “to inflate”). Within a few billionths of a second, the Universe increased its size by a factor of 10 × 50. During the inflationary period that lasted from the Big Bang to 10 × -32 s. "quantum fluctuations" were observed, caused by the spontaneous formation of particle/antiparticle pairs, giving space-time a rather irregular and complex shape. These fluctuations formed the basis of gravitational disturbances of homogeneity, which, being insignificant at first, grew over time and eventually formed the giant cosmic structures observed today, such as galaxies and clusters of galaxies. Particles of matter and antimatter, colliding, were mutually destroyed and produced radiation. Nevertheless, in this game of destruction, a surplus of matter was preserved: it made up the modern Universe.

Quarks

About 10×-35 s after the Big Bang, the first particles began to form - quarks, antiquarks, W particles, Z particles and electrons.

The combination of several quarks subsequently formed protons, neutrons and their antiparticles. The protons and antiprotons annihilated each other, producing electromagnetic radiation. Only at this moment did the weak nuclear and electromagnetic interactions separate.

These phenomena occurred between 10×-32 and 10×-5 s after the Big Bang, when the first atomic nuclei were formed. With their birth, matter began to dominate over the radiation that had dominated before. However, the temperature of the Universe reached another 10 billion degrees, so radiation and matter turned into each other.

Only about 300 thousand years after the Big Bang, when the temperature dropped to 3300°C, the Universe, which had previously been a formless cloud, became transparent to electromagnetic radiation. And then the first atoms of hydrogen, helium and lithium began to form - the lightest elements of the Universe.

Background radiation

About 300 thousand years after the Big Bang, cosmic background radiation appeared - the closest radiation to the Big Bang that we receive today. This is the first type of radiation that, in the now tenuous Universe, is not immediately captured by atomic or subatomic particles, but wanders through space in the form of photons. From this moment on, the primary matter begins to gradually form into stars, quasars and galaxies. Today, with the help of the most powerful telescopes, we are trying to take a look at these objects - the oldest and most distant in our Universe. Any additional information obtained from them could allow us to better understand the most mysterious moment in our history - the Big Bang.

Models of the Universe

In the 1920s, the idea of ​​a universe in which repulsive and attractive gravitational forces were in a delicate balance, made possible by the “cosmological constant” speculatively introduced by Albert Einstein in his general theory of relativity, was popular among cosmologists. He introduced this constant in order to explain the presence of a repulsive force of matter, which was supposed to balance the gravitational attraction. This was necessary to obtain an equilibrium cosmological model - a property considered basic for all models of our Universe.

Extension

Meanwhile, many astronomers noted that most galaxies exhibited redshifted lines in their light spectrum, a phenomenon known as “redshift.” This fact lends itself to a simple explanation if it is perceived as the result of the Doppler effect - the same thing due to which the sound of a retreating siren is heard lower than that of an approaching one. All this made sense if we took it for granted that galaxies were moving away from each other. A fundamental contribution to this research was made by the German astronomer Karl Wirtz: having studied in detail about forty galaxies, he discovered that the weaker their light, the farther they are from us, the stronger the red shift in their spectra. This meant that more distant galaxies were moving away faster than nearby ones. But to be convinced of the correctness of Wirtz’s conclusions, we had to wait for the research of Edwin Hubble.

Unstable space

Russian mathematician Alexander Friedman and Belgian astronomer Georges-Henri Lemaitre concluded that, despite the introduction of a cosmological constant, Einstein's Universe is unstable and a small fluctuation would be enough to cause it to expand or contract indefinitely. Hubble's observations led to the conclusion that the Universe is expanding. Lemaitre also developed the theory that the Universe originates from the “primordial atom” that gave rise to everything. Despite numerous data supporting this theory, it has been subjected to severe criticism. However, the idea did not die; on the contrary, it was supported by physicist George Gamow, who theoretically confirmed the possibility of the birth of the Universe as a result of a colossal explosion.

Stationary Universe

Meanwhile, another astronomer, Fred Hoyle, put forward the idea that the Universe could be expanding in a “steady state”: galaxies are moving away from each other, but new matter is constantly being created in the space between them. It was Hoyle who ironically called his colleagues’ hypothesis the “Big Bang.” But in the end, the scientific world supported the Big Bang hypothesis put forward by Gamow, and in the late 1960s it was transformed into a specific theory, confirmed in the late 1990s by the COBE and WMAP satellites.

Background radiation

A few hundred seconds after the Big Bang, the radius of the Universe was only a few light minutes, and the matter already included the basic elements of atoms - electrons, protons, neutrons interacting with each other, as well as neutrinos and photons (energy-transferring particles). When temperatures dropped to about 3300°C several hundred thousand years after the Big Bang, the number of collisions between photons and other particles decreased, and photons began to spread freely throughout the Universe.

It's getting colder and colder

The expansion entailed a further decrease in temperature, eventually dropping to 3 K, that is, only three degrees above absolute zero (-273 ° C). This temperature was “imprinted” on wandering photons, which, colliding less and less with other particles in an increasingly less dense Universe, have survived to this day. Today they are considered the most important witnesses of those distant times. It is wandering photons that form the so-called “background cosmic radiation.” It was discovered in 1964 by radio astronomers Arno Penzias and Robert Wilson, who were awarded the Nobel Prize in Physics in 1978.

Opened by accident

In fact, the researchers were setting up a new type of antenna for receiving microwaves. During the work, scientists received unknown radiation, and at first they decided that it was of terrestrial origin. But soon Penzias and Wilson realized that they were “listening” to cosmic radiation, the existence of which Gamow and his colleagues had assumed back in 1948 - something like the “echo” of the Big Bang. The discovery of background radiation was of enormous importance, since the standard model of the Universe provided for the presence of a uniform signal in it, propagating at a wavelength of about a millimeter and penetrating the entire space. This is exactly what scientists discovered.

From satellites

The discovery of Penzias and Wilson has been tested several times over the years, but has always been confirmed. Tests were carried out from aboard balloons (for example, the Boomerang experiment, carried out jointly by Italy and the USA). Three satellites (COBE, WMAP and Planck) were specifically designed to study background radiation and produced excellent results, especially the last two, which made it possible to measure the radiation and obtain details that were previously inaccessible. Thanks to the analysis of data received from satellites, differences in the temperature of background radiation were discovered by only hundred thousandths of a degree. This small “ripple” is like the genetic code of a living being: it determines the evolution of the Universe.

The discovery of background radiation became the most important evidence in favor of the Big Bang model, burying Hoyle's theory of a stationary Universe.

Doubts that arise

If we could truly understand how the Big Bang happened, we would answer a thousand unanswered questions about the birth of the Universe and its structure. But there are no answers to these questions yet, despite the most modern instruments at the disposal of astronomers. The main and most difficult question is how and why the Big Bang occurred.

Our capabilities in studying the past of the Universe extend into the depths of time and stop, as already mentioned, at the point 10 × -43 s after the Big Bang. Only theoretical physics can understand what happened before this moment, and only new hypotheses will take us to the time “before” the Big Bang.

Dark matter and dark energy

Another important topic that may be explained by the Big Bang is the origin of dark matter and dark energy. The Universe consists of only 5% of matter, which we can observe in traditional ways, for example, through a telescope, and which appears to us in the form of stars, nebulae, and galaxies. The rest is 27% dark matter and 68% dark energy. Regarding dark matter, some specific hypotheses have been put forward today: this matter is invisible, it detects its presence in galaxies and galaxy clusters due to its gravitational force, it could consist of several still unknown types of particles, neutrinos (if their mass is not zero) or stars of exceptionally low brightness.

Dark energy, on the other hand, is still a mystery. What is known about it is that it acts as a repulsive force and causes the Universe to expand at an accelerating rate, rather than decelerating, as would be expected if this energy did not exist.

Redshift

While some questions challenge those who study the origins of the universe, others challenge the Big Bang theory itself. The first of these questions concerns the redshift of light from galaxies. Some astrophysicists, including the American astronomer Halton Arp, believe that the red shift is caused not only by the removal of galaxies, but also by a phenomenon associated with the very nature of the observed objects. If this is so, then part of the support on which the theory of the expansion of the Universe rests will collapse. Those who still support Fred Hoyle's theory of a stationary universe base their polemics on this very thesis. If Arp is right, the Big Bang theory is simply not needed to explain the birth of the Universe. However, what Arp proposes is met with rebuttals from supporters of the theory of the expansion of the Universe.

Cyclic Universe

The theories of the Big Bang and the stationary Universe are not the only ones that explain the existence of our world. There is at least one more theory that suggests the cyclical existence of the Universe. According to this theory, whenever the Universe comes to the end of its evolution, it “starts over” with a new Big Bang. Perhaps, with each rebirth, the Universe “forgets” the characteristics of its past and forms new physical laws that are born at the stage of inflation.

How did our Universe appear? 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 appeared as a result of a gigantic explosion that not only generated 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. 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 the state of cosmic evolution that is taking place now.

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

Age of Singularity

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

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

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

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

The Age of Inflation

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

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

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

Cooling era

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

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

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

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

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

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

The Age of Structure (Hierarchical Age)

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

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

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

Long-term predictions for the future of the Universe

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

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

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

The Big Bang - like this

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

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

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

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

History of the Big Bang Theory

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

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

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

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

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

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

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

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

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

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

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

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