« Science fiction can be useful - it stimulates the imagination and relieves fear of the future. However, the scientific facts can be much more striking. Science fiction didn't even envision things like black holes.»
Stephen Hawking

In the depths of the universe for man lies countless mysteries and mysteries. One of them is black holes - objects that even the greatest minds of mankind cannot understand. Hundreds of astrophysicists are trying to discover the nature of black holes, but at this stage we have not even proved their existence in practice.

Film directors dedicate their films to them, and among ordinary people, black holes have become such a cult phenomenon that they are identified with the end of the world and imminent death. They are feared and hated, but at the same time they are idolized and bow before the unknown, which these strange fragments of the Universe are fraught with. Agree, to be swallowed up by a black hole is that kind of romance. With their help, it is possible, and they can also become guides for us in.

The yellow press often speculates on the popularity of black holes. Finding headlines in newspapers related to the end of the world on the planet due to another collision with a supermassive black hole is not a problem. Much worse is that the illiterate part of the population takes everything seriously and raises a real panic. To bring some clarity, we will go on a journey to the origins of the discovery of black holes and try to understand what it is and how to relate to it.

invisible stars

It so happened that modern physicists describe the structure of our Universe with the help of the theory of relativity, which Einstein carefully provided to mankind at the beginning of the 20th century. All the more mysterious are black holes, on the event horizon of which all the laws of physics known to us, including Einstein's theory, cease to operate. Isn't that wonderful? In addition, the conjecture about the existence of black holes was expressed long before the birth of Einstein himself.

In 1783, there was a significant increase in scientific activity in England. In those days, science went side by side with religion, they got along well together, and scientists were no longer considered heretics. Moreover, priests were engaged in scientific research. One of these servants of God was the English pastor John Michell, who asked himself not only questions of life, but also quite scientific tasks. Michell was a very titled scientist: initially he was a teacher of mathematics and ancient linguistics in one of the colleges, and after that he was admitted to the Royal Society of London for a number of discoveries.

John Michell dealt with seismology, but in his spare time he liked to think about the eternal and the cosmos. This is how he came up with the idea that somewhere in the depths of the Universe there may exist supermassive bodies with such powerful gravity that in order to overcome the gravitational force of such a body, it is necessary to move at a speed equal to or higher than the speed of light. If we accept such a theory as true, then even light will not be able to develop the second cosmic velocity (the speed necessary to overcome the gravitational attraction of the leaving body), so such a body will remain invisible to the naked eye.

Michell called his new theory "dark stars", and at the same time tried to calculate the mass of such objects. He expressed his thoughts on this matter in an open letter to the Royal Society of London. Unfortunately, in those days, such research was not of particular value to science, so Michell's letter was sent to the archive. Only two hundred years later, in the second half of the 20th century, it was found among thousands of other records carefully stored in the ancient library.

The first scientific evidence for the existence of black holes

After the release of Einstein's General Theory of Relativity, mathematicians and physicists seriously set about solving the equations presented by the German scientist, which were supposed to tell us a lot about the structure of the Universe. The German astronomer, physicist Karl Schwarzschild decided to do the same in 1916.

The scientist, using his calculations, came to the conclusion that the existence of black holes is possible. He was also the first to describe what was later called the romantic phrase "event horizon" - an imaginary boundary of space-time at a black hole, after crossing which there comes a point of no return. Nothing escapes from the event horizon, not even light. It is beyond the event horizon that the so-called “singularity” occurs, where the laws of physics known to us cease to operate.

Continuing to develop his theory and solving equations, Schwarzschild discovered new secrets of black holes for himself and the world. So, he was able to calculate, solely on paper, the distance from the center of a black hole, where its mass is concentrated, to the event horizon. Schwarzschild called this distance the gravitational radius.

Despite the fact that mathematically Schwarzschild's solutions were exceptionally correct and could not be refuted, the scientific community of the early 20th century could not immediately accept such a shocking discovery, and the existence of black holes was written off as a fantasy, which now and then manifested itself in the theory of relativity. For the next fifteen years, the study of space for the presence of black holes was slow, and only a few adherents of the theory of the German physicist were engaged in it.

Stars that give birth to darkness

After Einstein's equations were taken apart, it was time to use the conclusions drawn to understand the structure of the Universe. In particular, in the theory of the evolution of stars. It's no secret that nothing in our world lasts forever. Even the stars have their own cycle of life, albeit longer than a person.

One of the first scientists who became seriously interested in stellar evolution was the young astrophysicist Subramanyan Chandrasekhar, a native of India. In 1930, he published a scientific work that described the alleged internal structure of stars, as well as their life cycles.

Already at the beginning of the 20th century, scientists guessed about such a phenomenon as gravitational contraction (gravitational collapse). At a certain point in its life, a star begins to contract at a tremendous rate under the influence of gravitational forces. As a rule, this happens at the moment of the death of a star, however, with a gravitational collapse, there are several ways for the further existence of a red-hot ball.

Chandrasekhar's supervisor, Ralph Fowler, a respected theoretical physicist in his time, suggested that during a gravitational collapse, any star turns into a smaller and hotter one - a white dwarf. But it turned out that the student "broke" the teacher's theory, which was shared by most physicists at the beginning of the last century. According to the work of a young Hindu, the death of a star depends on its initial mass. For example, only those stars whose mass does not exceed 1.44 times the mass of the Sun can become white dwarfs. This number has been called the Chandrasekhar limit. If the mass of the star exceeded this limit, then it dies in a completely different way. Under certain conditions, such a star at the time of death can be reborn into a new, neutron star - another mystery of the modern Universe. The theory of relativity, on the other hand, tells us one more option - the compression of a star to ultra-small values, and here the most interesting begins.

In 1932, an article appeared in one of the scientific journals in which the brilliant physicist from the USSR Lev Landau suggested that during the collapse, a supermassive star is compressed into a point with an infinitesimal radius and infinite mass. Despite the fact that such an event is very difficult to imagine from the point of view of an unprepared person, Landau was not far from the truth. The physicist also suggested that, according to the theory of relativity, gravity at such a point would be so great that it would begin to distort space-time.

Astrophysicists liked Landau's theory, and they continued to develop it. In 1939, in America, thanks to the efforts of two physicists - Robert Oppenheimer and Hartland Sneijder - a theory appeared that describes in detail a supermassive star at the time of collapse. As a result of such an event, a real black hole should have appeared. Despite the persuasiveness of the arguments, scientists continued to deny the possibility of the existence of such bodies, as well as the transformation of stars into them. Even Einstein distanced himself from this idea, believing that the star is not capable of such phenomenal transformations. Other physicists were not stingy in their statements, calling the possibility of such events ridiculous.
However, science always reaches the truth, you just have to wait a little. And so it happened.

The brightest objects in the universe

Our world is a collection of paradoxes. Sometimes things coexist in it, the coexistence of which defies any logic. For example, the term "black hole" would not be associated in a normal person with the expression "incredibly bright", but the discovery of the early 60s of the last century allowed scientists to consider this statement incorrect.

With the help of telescopes, astrophysicists managed to detect hitherto unknown objects in the starry sky, which behaved quite strangely despite the fact that they looked like ordinary stars. Studying these strange luminaries, the American scientist Martin Schmidt drew attention to their spectrography, the data of which showed results different from scanning other stars. Simply put, these stars were not like the others we are used to.

Suddenly it dawned on Schmidt, and he drew attention to the shift of the spectrum in the red range. It turned out that these objects are much further from us than the stars that we are used to seeing in the sky. For example, the object observed by Schmidt was located two and a half billion light-years from our planet, but shone as brightly as a star some hundred light-years away. It turns out that the light from one such object is comparable to the brightness of an entire galaxy. This discovery was a real breakthrough in astrophysics. The scientist called these objects "quasi-stellar" or simply "quasar".

Martin Schmidt continued to study new objects and found out that such a bright glow can be caused by only one reason - accretion. Accretion is the process of absorption of surrounding matter by a supermassive body with the help of gravity. The scientist came to the conclusion that in the center of quasars there is a huge black hole, which with incredible force draws into itself the matter surrounding it in space. In the process of absorption of matter by the hole, the particles are accelerated to enormous speeds and begin to glow. The peculiar luminous dome around a black hole is called an accretion disk. Its visualization was well demonstrated in Christopher Nolan's film "Interstellar", which gave rise to many questions "how can a black hole glow?".

To date, scientists have found thousands of quasars in the starry sky. These strange, incredibly bright objects are called the beacons of the universe. They allow us to imagine the structure of the cosmos a little better and get closer to the moment from which it all began.

Despite the fact that astrophysicists have been obtaining indirect evidence for the existence of supermassive invisible objects in the Universe for many years, the term "black hole" did not exist until 1967. To avoid complicated names, the American physicist John Archibald Wheeler proposed calling such objects "black holes". Why not? To some extent they are black, because we cannot see them. In addition, they attract everything, you can fall into them, just like in a real hole. And to get out of such a place according to modern laws of physics is simply impossible. However, Stephen Hawking claims that when traveling through a black hole, you can get into another Universe, another world, and this is hope.

Fear of infinity

Due to the excessive mystery and romanticization of black holes, these objects have become a real horror story among people. The yellow press likes to speculate on the illiteracy of the population, giving out amazing stories about how a huge black hole is moving towards our Earth, which will swallow the solar system in a matter of hours, or simply emit waves of toxic gas towards our planet.

Especially popular is the topic of destroying the planet with the help of the Large Hadron Collider, which was built in Europe in 2006 on the territory of the European Council for Nuclear Research (CERN). The wave of panic began as someone's stupid joke, but grew like a snowball. Someone started a rumor that a black hole could form in the particle accelerator of the collider, which would swallow our planet entirely. Of course, the indignant people began to demand a ban on experiments at the LHC, afraid of such an outcome. Lawsuits began to come to the European Court demanding to close the collider, and the scientists who created it to be punished to the fullest extent of the law.

In fact, physicists do not deny that when particles collide in the Large Hadron Collider, objects similar in properties to black holes can appear, but their size is at the level of elementary particle sizes, and such “holes” exist for such a short time that we cannot even record their occurrence.

One of the main experts who are trying to dispel the wave of ignorance in front of people is Stephen Hawking - the famous theoretical physicist, who, moreover, is considered a real "guru" regarding black holes. Hawking proved that black holes do not always absorb the light that appears in accretion disks, and some of it is scattered into space. This phenomenon has been called Hawking radiation, or black hole evaporation. Hawking also established a relationship between the size of a black hole and the rate of its "evaporation" - the smaller it is, the less it exists in time. And this means that all opponents of the Large Hadron Collider should not worry: black holes in it will not be able to exist even for a millionth of a second.

Theory not proven in practice

Unfortunately, the technologies of mankind at this stage of development do not allow us to test most of the theories developed by astrophysicists and other scientists. On the one hand, the existence of black holes is quite convincingly proven on paper and deduced using formulas in which everything converged with every variable. On the other hand, in practice, we have not yet managed to see a real black hole with our own eyes.

Despite all the disagreements, physicists suggest that in the center of each of the galaxies there is a supermassive black hole, which collects stars into clusters with its gravity and makes you travel around the Universe in a large and friendly company. In our Milky Way galaxy, according to various estimates, there are from 200 to 400 billion stars. All these stars revolve around something that has a huge mass, around something that we cannot see with a telescope. It is most likely a black hole. Should she be afraid? - No, at least not in the next few billion years, but we can make another interesting film about her.

Black holes - perhaps the most mysterious and enigmatic astronomical objects in our Universe, have attracted the attention of pundits and excite the imagination of science fiction writers since their discovery. What are black holes and what do they look like? Black holes are extinguished stars, due to their physical characteristics, which have such a high density and such powerful gravity that even light cannot escape from them.

The history of the discovery of black holes

For the first time, the theoretical existence of black holes, long before their actual discovery, was suggested by someone D. Michel (an English priest from Yorkshire, who is fond of astronomy at his leisure) back in 1783. According to his calculations, if we take ours and compress it (in modern computer terms, archive it) to a radius of 3 km, such a large (just huge) gravitational force is formed that even light cannot leave it. This is how the concept of “black hole” appeared, although in fact it is not black at all, in our opinion, the term “dark hole” would be more appropriate, because it is precisely the absence of light that takes place.

Later, in 1918, the great scientist Albert Einstein wrote about the issue of black holes in the context of the theory of relativity. But only in 1967, through the efforts of the American astrophysicist John Wheeler, the concept of black holes finally won a place in academic circles.

Be that as it may, both D. Michel, and Albert Einstein, and John Wheeler in their works assumed only the theoretical existence of these mysterious celestial objects in outer space, however, the true discovery of black holes took place in 1971, it was then that they were first noticed in space. telescope.

This is what a black hole looks like.

How do black holes form in space?

As we know from astrophysics, all stars (including our Sun) have some limited amount of fuel. And although the life of a star can last billions of light years, sooner or later this conditional supply of fuel comes to an end, and the star “goes out”. The process of "extinction" of a star is accompanied by intense reactions, during which the star undergoes a significant transformation and, depending on its size, can turn into a white dwarf, a neutron star, or a black hole. Moreover, the largest stars, which have incredibly impressive dimensions, usually turn into a black hole - due to the compression of these most incredible sizes, the mass and gravitational force of the newly formed black hole multiply, which turns into a kind of galactic vacuum cleaner - absorbs everything and everything around it.

A black hole swallows a star.

A small remark - our Sun, by galactic standards, is not a large star at all, and after fading, which will occur in about a few billion years, most likely it will not turn into a black hole.

But let's be honest with you - today, scientists do not yet know all the intricacies of the formation of a black hole, undoubtedly, this is an extremely complex astrophysical process, which itself can last millions of light years. Although it is possible to advance in this direction, the detection and subsequent study of the so-called intermediate black holes, that is, stars that are in a state of extinction, in which the active process of forming a black hole, is taking place. By the way, a similar star was discovered by astronomers in 2014 in the arm of a spiral galaxy.

How many black holes exist in the universe

According to the theories of modern scientists, there may be up to hundreds of millions of black holes in our Milky Way galaxy. There may be no less of them in the galaxy next to us, to which there is nothing to fly from our Milky Way - 2.5 million light years.

Theory of black holes

Despite the huge mass (which is hundreds of thousands of times greater than the mass of our Sun) and the incredible strength of gravity, it was not easy to see black holes through a telescope, because they do not emit light at all. Scientists managed to notice a black hole only at the moment of its "meal" - the absorption of another star, at this moment a characteristic radiation appears, which can already be observed. Thus, the black hole theory has found actual confirmation.

Properties of black holes

The main property of a black hole is its incredible gravitational fields, which do not allow the surrounding space and time to remain in their usual state. Yes, you heard right, time inside a black hole flows many times slower than usual, and if you were there, then returning back (if you were so lucky, of course) you would be surprised to notice that centuries have passed on Earth, and you won’t even grow old have time. Although let's be truthful, if you were inside a black hole, you would hardly have survived, since the gravitational force there is such that any material object would simply be torn apart, not even into parts, into atoms.

But if you were even close to a black hole, within the range of its gravitational field, then you would also have a hard time, because the more you resisted its gravity, trying to fly away, the faster you would fall into it. The reason for this seemingly paradox is the gravitational vortex field, which all black holes possess.

What if a person falls into a black hole

Evaporation of black holes

The English astronomer S. Hawking discovered an interesting fact: black holes also, it turns out, emit evaporation. True, this applies only to holes of relatively small mass. The powerful gravity around them creates pairs of particles and antiparticles, one of the pair is pulled inward by the hole, and the second is ejected outward. Thus, a black hole radiates hard antiparticles and gamma rays. This evaporation or radiation from a black hole was named after the scientist who discovered it - "Hawking radiation".

The biggest black hole

According to the theory of black holes, in the center of almost all galaxies there are huge black holes with masses from several million to several billion solar masses. And relatively recently, scientists have discovered the two largest black holes known to date, they are in two nearby galaxies: NGC 3842 and NGC 4849.

NGC 3842 is the brightest galaxy in the constellation Leo, located at a distance of 320 million light-years from us. In the center of it there is a huge black hole with a mass of 9.7 billion solar masses.

NGC 4849 is a galaxy in the Coma cluster, 335 million light-years away, boasting an equally impressive black hole.

The zones of action of the gravitational field of these giant black holes, or in academic terms, their event horizon, is about 5 times the distance from the Sun to! Such a black hole would eat our solar system and not even choke.

The smallest black hole

But there are very small representatives in the vast family of black holes. So the most dwarf black hole discovered by scientists at the moment in its mass is only 3 times the mass of our Sun. In fact, this is the theoretical minimum necessary for the formation of a black hole, if that star were a little smaller, the hole would not have formed.

Black holes are cannibals

Yes, there is such a phenomenon, as we wrote above, black holes are a kind of "galactic vacuum cleaners" that absorb everything around them, including ... other black holes. Recently, astronomers have discovered that a black hole from one galaxy is being eaten by another large black glutton from another galaxy.

• According to the hypotheses of some scientists, black holes are not only galactic vacuum cleaners that suck everything into themselves, but under certain circumstances they themselves can generate new universes.
• Black holes can evaporate over time. We wrote above that it was discovered by the English scientist Stephen Hawking that black holes have the property of radiation, and after some very long period of time, when there is nothing to absorb around, the black hole will begin to evaporate more, until eventually it gives up all its mass into surrounding space. Although this is only an assumption, a hypothesis.
• Black holes slow down time and bend space. We have already written about time dilation, but space in the conditions of a black hole will be completely curved.
• Black holes limit the number of stars in the universe. Namely, their gravitational fields prevent the cooling of gas clouds in space, from which, as you know, new stars are born.

Black holes on the Discovery Channel, video

And in conclusion, we offer you an interesting scientific documentary about black holes from the Discovery channel.

Every person who gets acquainted with astronomy sooner or later experiences a strong curiosity about the most mysterious objects in the universe - black holes. These are the real masters of darkness, capable of "swallowing" any atom passing nearby and not letting even light escape - their attraction is so powerful. These objects present a real challenge for physicists and astronomers. The former still cannot understand what happens to the matter that has fallen inside the black hole, and the latter, although they explain the most energy-consuming phenomena of space by the existence of black holes, have never had the opportunity to observe any of them directly. We will talk about these most interesting celestial objects, find out what has already been discovered and what remains to be known in order to lift the veil of secrecy.

What is a black hole?

The name "black hole" (in English - black hole) was proposed in 1967 by the American theoretical physicist John Archibald Wheeler (see photo on the left). It served to designate a celestial body, the attraction of which is so strong that even light does not let go of itself. Therefore, it is "black" because it does not emit light.

indirect observations

This is the reason for such mystery: since black holes do not glow, we cannot see them directly and are forced to look for and study them, using only indirect evidence that their existence leaves in the surrounding space. In other words, if a black hole engulfs a star, we can't see the black hole, but we can observe the devastating effects of its powerful gravitational field.

Laplace's intuition

Despite the fact that the expression "black hole" to refer to the hypothetical final stage of the evolution of a star that collapsed into itself under the influence of gravity appeared relatively recently, the idea of ​​the possibility of the existence of such bodies arose more than two centuries ago. The Englishman John Michell and the Frenchman Pierre-Simon de Laplace independently hypothesized the existence of "invisible stars"; while they were based on the usual laws of dynamics and Newton's law of universal gravitation. Today, black holes have received their correct description based on Einstein's general theory of relativity.

In his work “Statement of the system of the world” (1796), Laplace wrote: “A bright star of the same density as the Earth, with a diameter 250 times greater than the diameter of the Sun, due to its gravitational attraction, would not allow light rays to reach us. Therefore, it is possible that the largest and brightest celestial bodies are invisible for this reason.

Invincible Gravity

Laplace's idea was based on the concept of escape velocity (second cosmic velocity). A black hole is such a dense object that its attraction is able to detain even light, which develops the highest speed in nature (almost 300,000 km / s). In practice, in order to escape from a black hole, you need a speed faster than the speed of light, but this is impossible!

This means that a star of this kind would be invisible, since even light would not be able to overcome its powerful gravity. Einstein explained this fact through the phenomenon of light deflection under the influence of a gravitational field. In reality, near a black hole, space-time is so curved that the paths of light rays also close on themselves. In order to turn the Sun into a black hole, we will have to concentrate all its mass in a ball with a radius of 3 km, and the Earth will have to turn into a ball with a radius of 9 mm!

Types of black holes

About ten years ago, observations suggested the existence of two types of black holes: stellar, whose mass is comparable to the mass of the Sun or slightly exceeds it, and supermassive, whose mass is from several hundred thousand to many millions of solar masses. However, relatively recently, high-resolution x-ray images and spectra obtained from artificial satellites such as Chandra and XMM-Newton brought to the fore the third type of black hole - with an average mass exceeding the mass of the Sun by thousands of times.

stellar black holes

Stellar black holes became known earlier than others. They form when a high-mass star, at the end of its evolutionary path, runs out of nuclear fuel and collapses into itself due to its own gravity. A star-shattering explosion (known as a “supernova explosion”) has catastrophic consequences: if the core of a star is more than 10 times the mass of the Sun, no nuclear force can withstand the gravitational collapse that will result in the appearance of a black hole.

Supermassive black holes

Supermassive black holes, first noted in the cores of some active galaxies, have a different origin. There are several hypotheses regarding their birth: a stellar black hole that devours all the stars surrounding it for millions of years; a merged cluster of black holes; a colossal cloud of gas collapsing directly into a black hole. These black holes are among the most energetic objects in space. They are located in the centers of very many galaxies, if not all. Our Galaxy also has such a black hole. Sometimes, due to the presence of such a black hole, the cores of these galaxies become very bright. Galaxies with black holes in the center, surrounded by a large amount of falling matter and, therefore, capable of producing an enormous amount of energy, are called "active", and their nuclei are called "active galactic nuclei" (AGN). For example, quasars (the most distant space objects from us available to our observation) are active galaxies, in which we see only a very bright nucleus.

Medium and "mini"

Another mystery remains the medium-mass black holes, which, according to recent studies, may be at the center of some globular clusters, such as M13 and NCC 6388. Many astronomers are skeptical about these objects, but some recent research suggests the presence of black holes. medium-sized even not far from the center of our Galaxy. English physicist Stephen Hawking also put forward a theoretical assumption about the existence of the fourth type of black hole - a "mini-hole" with a mass of only a billion tons (which is approximately equal to the mass of a large mountain). We are talking about primary objects, that is, those that appeared in the first moments of the life of the Universe, when the pressure was still very high. However, no trace of their existence has yet been discovered.

How to find a black hole

Just a few years ago, a light came on over black holes. Thanks to constantly improving instruments and technologies (both terrestrial and space), these objects are becoming less and less mysterious; more precisely, the space surrounding them becomes less mysterious. Indeed, since the black hole itself is invisible, we can only recognize it if it is surrounded by enough matter (stars and hot gas) orbiting it at a small distance.

Watching double systems

Some stellar black holes have been discovered by observing the orbital motion of a star around an invisible binary companion. Close binary systems (that is, consisting of two stars very close to each other), in which one of the companions is invisible, are a favorite object of observation for astrophysicists looking for black holes.

An indication of the presence of a black hole (or neutron star) is the strong emission of X-rays, caused by a complex mechanism, which can be schematically described as follows. Due to its powerful gravity, a black hole can rip matter out of a companion star; this gas is distributed in the form of a flat disk and falls in a spiral into the black hole. Friction resulting from collisions between particles of infalling gas heats the inner layers of the disk to several million degrees, which causes powerful X-ray emission.

X-ray observations

Observations in X-rays of objects in our Galaxy and neighboring galaxies, which have been carried out for several decades, have made it possible to detect compact binary sources, about a dozen of which are systems containing black hole candidates. The main problem is to determine the mass of an invisible celestial body. The value of the mass (albeit not very accurate) can be found by studying the motion of the companion or, which is much more difficult, by measuring the X-ray intensity of the incident matter. This intensity is connected by an equation with the mass of the body on which this substance falls.

Nobel Laureate

Something similar can be said about the supermassive black holes observed in the cores of many galaxies, whose masses are estimated by measuring the orbital velocities of the gas falling into the black hole. In this case, caused by a powerful gravitational field of a very large object, a rapid increase in the speed of gas clouds orbiting in the center of galaxies is revealed by observations in the radio range, as well as in optical beams. Observations in the X-ray range can confirm the increased release of energy caused by the fall of matter into the black hole. Research in X-rays in the early 1960s was started by the Italian Riccardo Giacconi, who worked in the USA. He was awarded the Nobel Prize in 2002 in recognition of his "groundbreaking contributions to astrophysics that led to the discovery of X-ray sources in space."

Cygnus X-1: the first candidate

Our Galaxy is not immune from the presence of black hole candidate objects. Fortunately, none of these objects are close enough to us to pose a danger to the existence of the Earth or the solar system. Despite the large number of noted compact X-ray sources (and these are the most likely candidates for finding black holes there), we are not sure that they actually contain black holes. The only one among these sources that does not have an alternative version is the close binary Cygnus X-1, that is, the brightest X-ray source in the constellation Cygnus.

massive stars

This system, with an orbital period of 5.6 days, consists of a very bright blue star of large size (its diameter is 20 times that of the sun, and its mass is about 30 times), easily distinguishable even in your telescope, and an invisible second star, the mass which is estimated at several solar masses (up to 10). Located at a distance of 6500 light years from us, the second star would be perfectly visible if it were an ordinary star. Its invisibility, the system's powerful X-rays, and finally its mass estimate lead most astronomers to believe that this is the first confirmed discovery of a stellar black hole.

Doubts

However, there are also skeptics. Among them is one of the largest researchers of black holes, physicist Stephen Hawking. He even made a bet with his American colleague Keel Thorne, a strong supporter of the classification of Cygnus X-1 as a black hole.

The dispute over the nature of the Cygnus X-1 object is not Hawking's only bet. Having devoted several decades to theoretical studies of black holes, he became convinced of the fallacy of his previous ideas about these mysterious objects. In particular, Hawking assumed that matter after falling into a black hole disappears forever, and with it all its informational baggage disappears. He was so sure of this that he made a bet on this subject in 1997 with his American colleague John Preskill.

Admitting a mistake

On July 21, 2004, in his speech at the Relativity Congress in Dublin, Hawking admitted that Preskill was right. Black holes do not lead to the complete disappearance of matter. Moreover, they have a certain kind of "memory". Inside them may well be stored traces of what they absorbed. Thus, by “evaporating” (that is, slowly emitting radiation due to the quantum effect), they can return this information to our Universe.

Black holes in the galaxy

Astronomers still have many doubts about the presence of stellar black holes in our Galaxy (like the one that belongs to the Cygnus X-1 binary system); but there is much less doubt about supermassive black holes.

In the center

There is at least one supermassive black hole in our galaxy. Its source, known as Sagittarius A*, is precisely located in the center of the plane of the Milky Way. Its name is explained by the fact that it is the most powerful radio source in the constellation Sagittarius. It is in this direction that both the geometric and physical centers of our galactic system are located. Located at a distance of about 26,000 light-years from us, a supermassive black hole associated with the source of radio waves Sagittarius A *, has a mass estimated at about 4 million solar masses, contained in a space whose volume is comparable to the volume of the solar system. Its relative proximity to us (this supermassive black hole is without a doubt the closest to Earth) has caused the object to come under particularly deep scrutiny by the Chandra space observatory in recent years. It turned out, in particular, that it is also a powerful source of X-rays (but not as powerful as sources in active galactic nuclei). Sagittarius A* is possibly the dormant remnant of what was the active core of our galaxy millions or billions of years ago.

Second black hole?

However, some astronomers believe that there is another surprise in our Galaxy. We are talking about a second black hole of average mass, holding together a cluster of young stars and not allowing them to fall into a supermassive black hole located in the center of the Galaxy itself. How can it be that at a distance of less than one light year from it there could be a star cluster with an age that has barely reached 10 million years, that is, by astronomical standards, very young? According to the researchers, the answer lies in the fact that the cluster was not born there (the environment around the central black hole is too hostile for star formation), but was “drawn” there due to the existence of a second black hole inside it, which has a mass of average values.

In orbit

The individual stars of the cluster, attracted by the supermassive black hole, began to shift towards the galactic center. However, instead of being dispersed into space, they remain together due to the attraction of a second black hole located at the center of the cluster. The mass of this black hole can be estimated from its ability to hold an entire star cluster "on a leash". A medium-sized black hole appears to revolve around the central black hole in about 100 years. This means that long-term observations over many years will allow us to "see" it.

A star can turn into a black hole by the end of its life. During this transformation, the star is compressed very strongly, while its mass is conserved. The star turns into a small but very heavy ball. If we assume that our planet Earth becomes a black hole, then its diameter in this state will be only 9 millimeters. But the Earth will not be able to turn into a black hole, because completely different reactions take place in the core of planets, not the same as in stars.

Such a strong compression and compaction of the star comes from the fact that under the influence of thermonuclear reactions in the center of the star, its force of attraction greatly increases and begins to attract the surface of the star to its center. Gradually, the rate at which the star contracts increases and eventually begins to exceed the speed of light. When a star reaches this state, it ceases to glow, because particles of light - quanta - cannot overcome the force of attraction. A star in this state ceases to emit light, it remains "inside" the gravitational radius - the boundary within which all objects are attracted to the surface of the star. Astronomers call this boundary the event horizon. And beyond this boundary, the black hole's gravity decreases. Since light particles cannot overcome the gravitational boundary of a star, a black hole can only be detected using instruments, for example, if for some unknown reason a spaceship or another body - a comet or an asteroid - starts to change its trajectory, then most likely it fell under the influence of the gravitational forces of a black hole . A controlled space object in such a situation must urgently turn on all the engines and leave the zone of dangerous attraction, and if there is not enough power, then it will inevitably be swallowed up by a black hole.

If the Sun could turn into a black hole, then the planets of the solar system would be inside the gravitational radius of the Sun and it would attract and absorb them. Luckily for us, this won't happen. only very large, massive stars can turn into a black hole. The sun is too small for that. In the process of evolution, the Sun will most likely become an extinct black dwarf. Other black holes that are already in space are not dangerous for our planet and earthly spacecraft - they are too far from us.

In the popular series "The Big Bang Theory", which you can watch, you will not learn the secrets of the creation of the Universe or the causes of black holes in space. The main characters are passionate about science and work in the department of physics at the university. They constantly get into various ridiculous situations that are fun to watch.

The boundless Universe is full of secrets, riddles and paradoxes. Despite the fact that modern science has made a huge leap forward in space exploration, much in this vast world remains incomprehensible to the human worldview. We know a lot about stars, nebulae, clusters and planets. However, in the vastness of the Universe there are such objects, the existence of which we can only guess. For example, we know very little about black holes. Basic information and knowledge about the nature of black holes is based on assumptions and conjectures. Astrophysicists and atomic scientists have been struggling with this issue for more than a dozen years. What is a black hole in space? What is the nature of such objects?

Talking about black holes in simple terms

To imagine what a black hole looks like, it is enough to see the tail of a train leaving the tunnel. The signal lights on the last car as the train deepens into the tunnel will decrease in size until they completely disappear from view. In other words, these are objects where, due to the monstrous attraction, even light disappears. Elementary particles, electrons, protons and photons are not able to overcome the invisible barrier, they fall into the black abyss of non-existence, that is why such a hole in space is called black. There is not the slightest bright spot inside it, solid blackness and infinity. What lies on the other side of a black hole is unknown.

This space vacuum cleaner has a colossal force of attraction and is able to absorb an entire galaxy with all clusters and superclusters of stars, with nebulae and dark matter to boot. How is this possible? It remains only to guess. The laws of physics known to us in this case are cracking at the seams and do not provide an explanation for the ongoing processes. The essence of the paradox lies in the fact that in a given section of the Universe, the gravitational interaction of bodies is determined by their mass. The process of absorption by one object of another is not affected by their qualitative and quantitative composition. Particles, having reached a critical amount in a certain area, enter another level of interaction, where gravitational forces become forces of attraction. The body, object, substance or matter under the influence of gravity begins to shrink, reaching a colossal density.

Approximately such processes occur during the formation of a neutron star, where stellar matter is compressed in volume under the influence of internal gravity. Free electrons combine with protons to form electrically neutral particles called neutrons. The density of this substance is enormous. A particle of matter the size of a piece of refined sugar has a weight of billions of tons. Here it would be appropriate to recall the general theory of relativity, where space and time are continuous quantities. Therefore, the compression process cannot be stopped halfway and therefore has no limit.

Potentially, a black hole looks like a hole in which there may be a transition from one part of space to another. At the same time, the properties of space and time itself change, twisting into a space-time funnel. Reaching the bottom of this funnel, any matter decays into quanta. What is on the other side of the black hole, this giant hole? Perhaps there is another other space where other laws operate and time flows in the opposite direction.

In the context of the theory of relativity, the theory of a black hole is as follows. The point in space, where gravitational forces have compressed any matter to microscopic dimensions, has a colossal force of attraction, the magnitude of which increases to infinity. A wrinkle of time appears, and space is curved, closing in one point. Objects swallowed by the black hole are unable to resist the force of retraction of this monstrous vacuum cleaner on their own. Even the speed of light possessed by quanta does not allow elementary particles to overcome the force of attraction. Any body that gets to such a point ceases to be a material object, merging with the space-time bubble.

Black holes in terms of science

If you ask yourself, how do black holes form? There will be no single answer. There are a lot of paradoxes and contradictions in the Universe that cannot be explained from the point of view of science. Einstein's theory of relativity allows only a theoretical explanation of the nature of such objects, but quantum mechanics and physics are silent in this case.

Trying to explain the ongoing processes by the laws of physics, the picture will look like this. An object formed as a result of colossal gravitational compression of a massive or supermassive cosmic body. This process has a scientific name - gravitational collapse. The term "black hole" first appeared in the scientific community in 1968, when the American astronomer and physicist John Wheeler tried to explain the state of stellar collapse. According to his theory, in place of a massive star that has undergone gravitational collapse, a spatial and temporal gap appears, in which an ever-growing compression acts. Everything that the star consisted of goes inside itself.

Such an explanation allows us to conclude that the nature of black holes is in no way related to the processes occurring in the Universe. Everything that happens inside this object does not affect the surrounding space in any way with one "BUT". The gravitational force of a black hole is so strong that it bends space, causing galaxies to rotate around black holes. Accordingly, the reason why galaxies take the form of spirals becomes clear. How long it will take for the huge Milky Way galaxy to disappear into the abyss of a supermassive black hole is unknown. A curious fact is that black holes can appear at any point in outer space, where ideal conditions are created for this. Such a wrinkle of time and space levels out the huge speeds with which the stars rotate and move in the space of the galaxy. Time in a black hole flows in another dimension. Within this region, no laws of gravity can be interpreted from the point of view of physics. This state is called a black hole singularity.

Black holes do not show any external identification signs, their existence can be judged by the behavior of other space objects that are affected by gravitational fields. The whole picture of the struggle for life and death takes place on the border of a black hole, which is covered by a membrane. This imaginary surface of the funnel is called the "event horizon". Everything that we see up to this limit is tangible and material.

Scenarios for the formation of black holes

Developing the theory of John Wheeler, we can conclude that the mystery of black holes is not in the process of its formation. The formation of a black hole occurs as a result of the collapse of a neutron star. Moreover, the mass of such an object should exceed the mass of the Sun by three or more times. The neutron star shrinks until its own light is no longer able to escape from the tight grip of gravity. There is a limit to the size to which a star can shrink to give birth to a black hole. This radius is called the gravitational radius. Massive stars at the final stage of their development should have a gravitational radius of several kilometers.

Today, scientists have obtained circumstantial evidence for the presence of black holes in a dozen x-ray binary stars. An X-ray star, pulsar or burster does not have a solid surface. In addition, their mass is greater than the mass of three Suns. The current state of outer space in the constellation Cygnus, the X-ray star Cygnus X-1, makes it possible to trace the formation of these curious objects.

Based on research and theoretical assumptions, there are four scenarios for the formation of black stars in science today:

• gravitational collapse of a massive star at the final stage of its evolution;
• collapse of the central region of the galaxy;
• the formation of black holes during the Big Bang;
• the formation of quantum black holes.

The first scenario is the most realistic, but the number of black stars with which we are familiar today exceeds the number of known neutron stars. And the age of the Universe is not so great that such a number of massive stars could go through the full process of evolution.

The second scenario has the right to life, and there is a vivid example of this - the supermassive black hole Sagittarius A *, sheltered in the center of our galaxy. The mass of this object is 3.7 solar masses. The mechanism of this scenario is similar to the scenario of gravitational collapse, with the only difference being that it is not the star that undergoes the collapse, but the interstellar gas. Under the influence of gravitational forces, the gas is compressed to a critical mass and density. At a critical moment, matter breaks up into quanta, forming a black hole. However, this theory is questionable, since astronomers at Columbia University recently identified satellites of the Sagittarius A* black hole. They turned out to be a lot of small black holes, which probably formed in a different way.

The third scenario is more theoretical and is related to the existence of the Big Bang theory. At the time of the formation of the Universe, part of the matter and gravitational fields fluctuated. In other words, the processes took a different path, not related to the known processes of quantum mechanics and nuclear physics.

The last scenario is focused on the physics of a nuclear explosion. In clumps of matter, in the process of nuclear reactions, under the influence of gravitational forces, an explosion occurs, in the place of which a black hole is formed. Matter explodes inward, absorbing all particles.

Existence and evolution of black holes

Having a rough idea of ​​the nature of such strange space objects, something else is interesting. What are the true sizes of black holes, how fast do they grow? The dimensions of black holes are determined by their gravitational radius. For black holes, the radius of the black hole is determined by its mass and is called the Schwarzschild radius. For example, if an object has a mass equal to the mass of our planet, then the Schwarzschild radius in this case is 9 mm. Our main luminary has a radius of 3 km. The average density of a black hole formed in the place of a star with a mass of 10⁸ solar masses will be close to the density of water. The radius of such formation will be 300 million kilometers.

It is likely that such giant black holes are located in the center of galaxies. To date, 50 galaxies are known, in the center of which there are huge time and space wells. The mass of such giants is billions of the mass of the Sun. One can only imagine what a colossal and monstrous force of attraction such a hole possesses.

As for small holes, these are mini-objects, the radius of which reaches negligible values, only 10¯¹² cm. The mass of such a crumb is 10¹⁴g. Such formations arose at the time of the Big Bang, but over time they increased in size and today they flaunt in outer space as monsters. The conditions under which the formation of small black holes took place, scientists today are trying to recreate in terrestrial conditions. For these purposes, experiments are carried out in electron colliders, through which elementary particles are accelerated to the speed of light. The first experiments made it possible to obtain quark-gluon plasma in laboratory conditions - matter that existed at the dawn of the formation of the Universe. Such experiments allow us to hope that a black hole on Earth is a matter of time. Another thing is whether such an achievement of human science will turn into a catastrophe for us and for our planet. By artificially creating a black hole, we can open Pandora's box.

Recent observations of other galaxies have allowed scientists to discover black holes whose dimensions exceed all conceivable expectations and assumptions. The evolution that occurs with such objects makes it possible to better understand why the mass of black holes grows, what is its real limit. Scientists have come to the conclusion that all known black holes have grown to their real size within 13-14 billion years. The difference in size is due to the density of the surrounding space. If a black hole has enough food within reach of the forces of gravity, it grows by leaps and bounds, reaching a mass of hundreds and thousands of solar masses. Hence the gigantic size of such objects located in the center of galaxies. A massive cluster of stars, huge masses of interstellar gas are abundant food for growth. When galaxies merge, black holes can merge together, forming a new supermassive object.

Judging by the analysis of evolutionary processes, it is customary to distinguish two classes of black holes:

• objects with a mass 10 times the solar mass;
• massive objects, the mass of which is hundreds of thousands, billions of solar masses.

There are black holes with an average intermediate mass equal to 100-10 thousand solar masses, but their nature is still unknown. There is approximately one such object per galaxy. The study of X-ray stars made it possible to find two average black holes at a distance of 12 million light years in the M82 galaxy. The mass of one object varies in the range of 200-800 solar masses. Another object is much larger and has a mass of 10-40 thousand solar masses. The fate of such objects is interesting. They are located near star clusters, gradually being attracted to a supermassive black hole located in the central part of the galaxy.

Our planet and black holes

Despite the search for clues about the nature of black holes, the scientific world is concerned about the place and role of a black hole in the fate of the Milky Way galaxy and, in particular, in the fate of planet Earth. The fold of time and space that exists at the center of the Milky Way gradually engulfs all existing objects around. Millions of stars and trillions of tons of interstellar gas have already been absorbed into the black hole. Over time, the turn will reach the arms of Cygnus and Sagittarius, in which the solar system is located, having traveled a distance of 27 thousand light years.

The other nearest supermassive black hole is in the central part of the Andromeda galaxy. This is about 2.5 million light years from us. Probably, before the time when our object Sagittarius A * absorbs its own galaxy, we should expect a merger of two neighboring galaxies. Accordingly, there will be a merger of two supermassive black holes into one, terrible and monstrous in size.

A completely different matter is small black holes. To absorb the planet Earth, a black hole with a radius of a couple of centimeters is enough. The problem is that, by nature, a black hole is a completely faceless object. No radiation or radiation comes from her womb, so it is quite difficult to notice such a mysterious object. Only from a close distance can one detect the curvature of the background light, which indicates that there is a hole in space in this region of the Universe.

To date, scientists have determined that the closest black hole to Earth is V616 Monocerotis. The monster is located 3000 light years from our system. In terms of size, this is a large formation, its mass is 9-13 solar masses. Another nearby object that threatens our world is the black hole Gygnus X-1. With this monster we are separated by a distance of 6000 light years. The black holes revealed in our neighborhood are part of a binary system, i.e. exist in close proximity to a star that feeds an insatiable object.

Conclusion

The existence in space of such mysterious and mysterious objects as black holes, of course, makes us be on our guard. However, everything that happens to black holes happens quite rarely, given the age of the universe and huge distances. For 4.5 billion years, the solar system has been at rest, existing according to the laws known to us. During this time, nothing of the kind, neither the distortion of space, nor the fold of time, appeared near the solar system. Probably, there are no suitable conditions for this. That part of the Milky Way, in which the Sun star system resides, is a calm and stable section of space.

Scientists admit the idea that the appearance of black holes is not accidental. Such objects play the role of orderlies in the Universe, destroying the excess of cosmic bodies. As for the fate of the monsters themselves, their evolution has not yet been fully studied. There is a version that black holes are not eternal and at a certain stage may cease to exist. It is no longer a secret to anyone that such objects are the most powerful sources of energy. What kind of energy it is and how it is measured is another matter.

Through the efforts of Stephen Hawking, science was presented with the theory that a black hole still radiates energy, losing its mass. In his assumptions, the scientist was guided by the theory of relativity, where all processes are interconnected with each other. Nothing just disappears without appearing somewhere else. Any matter can be transformed into another substance, while one type of energy goes to another energy level. This may be the case with black holes, which are a transitional portal from one state to another.

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