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Black hole: what's inside? Interesting facts and research. What is a black hole and why does it attract? Description, photo and video All about the black hole

Due to the relatively recent increase in interest in making popular science films on the topic of space exploration, the modern viewer has heard a lot about such phenomena as the singularity, or black hole. However, movies, obviously, do not reveal the entire nature of these phenomena, and sometimes even distort the constructed scientific theories for greater effectiveness. For this reason, the idea of many modern people about these phenomena is either completely superficial or completely erroneous. One of the solutions to this problem is this article, in which we will try to understand the existing research results and answer the question - what is a black hole?

In 1784, the English priest and naturalist John Michell first mentioned in a letter to the Royal Society some hypothetical massive body that has such a strong gravitational attraction that the second cosmic speed for it will exceed the speed of light. The second cosmic speed is the speed that a relatively small object will need to overcome the gravitational attraction of a celestial body and go beyond the closed orbit around this body. According to his calculations, a body with the density of the Sun and a radius of 500 solar radii will have on its surface a second cosmic speed equal to the speed of light. In this case, even the light will not leave the surface of such a body, and therefore this body will only absorb the incoming light and remain invisible to the observer - a kind of black spot against the background of dark space.

However, Michell's concept of a supermassive body did not attract much interest, until the work of Einstein. Let us recall that the latter defined the speed of light as the limiting speed of information transmission. In addition, Einstein expanded the theory of gravitation for speeds close to the speed of light (). As a result, it was no longer relevant to apply Newtonian theory to black holes.

Einstein's equation

As a result of applying general relativity to black holes and solving Einstein's equations, the main parameters of a black hole were revealed, of which there are only three: mass, electric charge and angular momentum. It should be noted the significant contribution of the Indian astrophysicist Subramanian Chandrasekhar, who created the fundamental monograph: "The Mathematical Theory of Black Holes."

Thus, the solution to Einstein's equations is presented by four options for four possible types of black holes:

BH without rotation and without charge - Schwarzschild's solution. One of the first descriptions of a black hole (1916) using Einstein's equations, but without taking into account two of the three body parameters. The solution of the German physicist Karl Schwarzschild makes it possible to calculate the external gravitational field of a spherical massive body. The peculiarity of the concept of BH by the German scientist is the presence of an event horizon and the one hidden behind it. Also, Schwarzschild was the first to calculate the gravitational radius, which received his name, which determines the radius of the sphere on which the event horizon for a body with a given mass would be located.
BH without rotation with charge - Reisner-Nordström solution. A solution put forward in 1916-1918, taking into account the possible electric charge of the black hole. This charge cannot be as large as desired and is limited due to the resulting electrical repulsion. The latter should be compensated by gravitational attraction.
BH with rotation and without charge - Kerr's solution (1963). A rotating Kerr black hole differs from a static one by the presence of the so-called ergosphere (about this and other components of the black hole - read on).
BH with rotation and charge - Kerr - Newman solution. This solution was calculated in 1965 and is currently the most complete, since it takes into account all three BH parameters. However, it is still assumed that in nature black holes have an insignificant charge.

Formation of a black hole

There are several theories about how a black hole forms and appears, the most famous of which is the formation of a star with sufficient mass as a result of gravitational collapse. This compression can end the evolution of stars with a mass of more than three solar masses. Upon completion of thermonuclear reactions inside such stars, they begin to rapidly collapse into superdense. If the gas pressure of the neutron star cannot compensate for the gravitational forces, that is, the mass of the star overcomes the so-called. the Oppenheimer - Volkov limit, then the collapse continues, with the result that matter is compressed into a black hole.

The second scenario, describing the birth of a black hole, is the compression of protogalactic gas, that is, interstellar gas that is at the stage of transformation into a galaxy or some kind of cluster. If there is insufficient internal pressure to compensate for the same gravitational forces, a black hole may appear.

Two other scenarios remain hypothetical:

The emergence of BH as a result - the so-called. primordial black holes.
Occurrence as a result of nuclear reactions at high energies. An example of such reactions is collider experiments.

Structure and physics of black holes

The Schwarzschild structure of a black hole includes only two elements, which were mentioned earlier: the singularity and the event horizon of the black hole. Briefly speaking about the singularity, it can be noted that it is impossible to draw a straight line through it, and also that within it most of the existing physical theories do not work. Thus, the physics of the singularity remains a mystery to scientists today. a black hole is a kind of border, crossing which, a physical object loses the ability to return back beyond its limits and will definitely "fall" into the singularity of the black hole.

The structure of a black hole becomes somewhat more complicated in the case of the Kerr solution, namely, in the presence of rotation of the BH. Kerr's solution assumes that the hole has an ergosphere. The ergosphere is a certain region outside the event horizon, inside which all bodies move in the direction of rotation of the black hole. This area is not yet exciting and it is possible to leave it, unlike the event horizon. The ergosphere is probably a kind of analogue of the accretion disk, which is rotating matter around massive bodies. If a static Schwarzschild black hole is represented as a black sphere, then the Kerry BH, due to the presence of the ergosphere, has the shape of an oblate ellipsoid, in the form of which we often saw BH in drawings, in old movies or video games.

How much does a black hole weigh? - The greatest theoretical material on the origin of a black hole is available for the scenario of its appearance as a result of the collapse of a star. In this case, the maximum mass of a neutron star and the minimum mass of a black hole are determined by the Oppenheimer - Volkov limit, according to which the lower limit of the BH mass is 2.5 - 3 solar masses. The heaviest black hole ever discovered (in the galaxy NGC 4889) has a mass of 21 billion solar masses. However, one should not forget about BHs, hypothetically arising as a result of nuclear reactions at high energies, such as those at colliders. The mass of such quantum black holes, in other words, "Planck black holes", has an order of magnitude, namely 2 · 10 −5 g.
The size of the black hole. The minimum BH radius can be calculated from the minimum mass (2.5 - 3 solar masses). If the gravitational radius of the Sun, that is, the area where the event horizon would be located, is about 2.95 km, then the minimum BH radius of 3 solar masses will be about nine kilometers. Such a relatively small size does not fit into the head when it comes to massive objects that attract everything around. However, for quantum black holes, the radius is - 10 −35 m.
The average density of a black hole depends on two parameters: mass and radius. The density of a black hole with a mass of the order of three solar masses is about 6 · 10 26 kg / m³, while the density of water is 1000 kg / m³. However, such small black holes have not been found by scientists. Most of the detected BHs have a mass of more than 10 5 solar masses. There is an interesting pattern according to which the more massive a black hole, the lower its density. In this case, a change in mass by 11 orders of magnitude leads to a change in density by 22 orders of magnitude. Thus, a black hole with a mass of 1 · 10 9 solar masses has a density of 18.5 kg / m³, which is one unit less than the density of gold. And BHs with a mass of more than 10 10 solar masses can have an average density less than the density of air. Based on these calculations, it is logical to assume that the formation of a black hole occurs not due to the compression of matter, but as a result of the accumulation of a large amount of matter in a certain volume. In the case of quantum BHs, their density can be about 1094 kg / m³.
The temperature of a black hole is also inversely proportional to its mass. This temperature is directly related to. The spectrum of this radiation coincides with the spectrum of an absolutely black body, that is, a body that absorbs all incident radiation. The radiation spectrum of an absolutely black body depends only on its temperature, then the BH temperature can be determined from the Hawking radiation spectrum. As mentioned above, the smaller the black hole, the more powerful this radiation is. At the same time, Hawking radiation remains hypothetical, since it has not yet been observed by astronomers. It follows from this that if Hawking radiation exists, then the temperature of the observed BHs is so low that it does not allow registering the indicated radiation. According to calculations, even the temperature of a hole with a mass of the order of the mass of the Sun is negligible (1 · 10 -7 K or -272 ° C). The temperature of quantum black holes can reach about 10 12 K, and with their rapid evaporation (about 1.5 minutes), such BHs can emit energy of the order of ten million atomic bombs. But, fortunately, the creation of such hypothetical objects will require an energy 10 14 times greater than that achieved today at the Large Hadron Collider. In addition, such phenomena have never been observed by astronomers.

What does a black hole consist of?

Another question worries, both scientists and those who are simply fond of astrophysics - what does a black hole consist of? There is no unambiguous answer to this question, since it is not possible to look beyond the event horizon surrounding any black hole. In addition, as mentioned earlier, theoretical models of a black hole provide for only 3 of its components: the ergosphere, the event horizon and the singularity. It is logical to assume that in the ergosphere there are only those objects that were attracted by the black hole, and which now revolve around it - various kinds of cosmic bodies and cosmic gas. The event horizon is only a thin implicit border, after falling beyond which, the same cosmic bodies are irretrievably attracted towards the last main component of the BH - the singularity. The nature of the singularity has not been studied today and it is too early to talk about its composition.

According to some assumptions, the black hole may be composed of neutrons. If we follow the scenario of a black hole as a result of the compression of a star to a neutron star with its subsequent contraction, then, probably, the main part of the black hole consists of neutrons, of which the neutron star itself consists. In simple words: when a star collapses, its atoms contract in such a way that electrons combine with protons, thereby forming neutrons. A similar reaction actually takes place in nature, while neutrino emission occurs with the formation of a neutron. However, these are only assumptions.

What happens if you fall into a black hole?

Falling into an astrophysical black hole stretches the body. Consider a hypothetical suicide astronaut walking into a black hole in nothing but a spacesuit, feet first. Crossing the event horizon, the astronaut will not notice any changes, despite the fact that he no longer has the opportunity to get out. At some point, the astronaut will reach a point (slightly behind the event horizon) at which deformation of his body will begin to occur. Since the gravitational field of a black hole is inhomogeneous and is represented by a force gradient increasing towards the center, the astronaut's legs will be subjected to a noticeably greater gravitational effect than, for example, the head. Then, due to gravity, or rather, tidal forces, the legs will "fall" faster. Thus, the body begins to gradually stretch in length. To describe this phenomenon, astrophysicists have come up with a rather creative term - spaghettification. Further stretching of the body is likely to decompose it into atoms, which, sooner or later, will reach a singularity. What a person will feel in this situation is anyone's guess. It is worth noting that the stretching effect of a body is inversely proportional to the mass of the black hole. That is, if a BH with a mass of three Suns instantly stretches / breaks the body, then the supermassive black hole will have lower tidal forces and, there are suggestions that some physical materials could “endure” such a deformation without losing their structure.

As is known, time flows more slowly near massive objects, which means that time for a suicide astronaut will flow much slower than for earthlings. In this case, perhaps he will outlive not only his friends, but also the Earth itself. Calculations will be required to determine how much time will slow down for the astronaut; however, from the above, it can be assumed that the astronaut will fall into the BH very slowly and, perhaps, simply will not live to see the moment when his body begins to deform.

It is noteworthy that for an observer outside, all bodies that have flown up to the event horizon will remain at the edge of this horizon until their image disappears. The reason for this phenomenon is the gravitational redshift. Simplifying somewhat, we can say that the light falling on the body of a suicide astronaut "frozen" at the event horizon will change its frequency due to its slowed down time. As time passes more slowly, the frequency of light will decrease and the wavelength will increase. As a result of this phenomenon, at the output, that is, for an external observer, the light will gradually shift towards the low-frequency - red. A shift of light along the spectrum will take place, as the suicide astronaut moves further and further from the observer, albeit almost imperceptibly, and his time passes more and more slowly. Thus, the light reflected by his body will soon go beyond the visible spectrum (the image will disappear), and in the future, the astronaut's body can be caught only in the infrared region, and later - in the radio frequency, and as a result, the radiation will be completely elusive.

Despite the above, it is assumed that in very large supermassive black holes, tidal forces do not change so much with distance and act almost uniformly on the falling body. In this case, the falling spaceship would retain its structure. A reasonable question arises - where does the black hole lead? This question can be answered by the work of some scientists linking two such phenomena as wormholes and black holes.

Back in 1935, Albert Einstein and Nathan Rosen, taking into account, put forward a hypothesis about the existence of so-called wormholes, connecting two points of space-time by a path in places of significant curvature of the latter - the Einstein-Rosen bridge or a wormhole. For such a powerful curvature of space, bodies with a gigantic mass would be required, with the role of which black holes would perfectly cope.

The Einstein-Rosen Bridge is considered an impassable wormhole because it is small and unstable.

A traversable wormhole is possible within the framework of the theory of black and white holes. Where the white hole is the output of information trapped in a black hole. The white hole is described in the framework of general relativity, but today it remains hypothetical and has not been discovered. Another model of a wormhole, proposed by American scientists Kip Thorne and his graduate student, Mike Morris, can be walkable. However, as in the case of the Morris-Thorne wormhole, and in the case of black and white holes, the possibility of travel requires the existence of so-called exotic matter, which has negative energy and also remains hypothetical.

Black holes in the universe

The existence of black holes was confirmed relatively recently (September 2015), but by that time there was already considerable theoretical material on the nature of BHs, as well as many candidate objects for the role of a black hole. First of all, the size of the BH should be taken into account, since the very nature of the phenomenon depends on them:

Stellar mass black hole... Such objects are formed as a result of the collapse of a star. As mentioned earlier, the minimum mass of a body capable of forming such a black hole is 2.5 - 3 solar masses.
Medium mass black holes... A conditional intermediate type of black holes that have increased due to the absorption of nearby objects, such as a gas accumulation, a neighboring star (in two-star systems) and other cosmic bodies.
Supermassive black hole... Compact objects with 10 5 -10 10 solar masses. The distinctive properties of such BHs are the paradoxically low density, as well as the weak tidal forces, which were mentioned earlier. It is such a supermassive black hole at the center of our Milky Way galaxy (Sagittarius A *, Sgr A *), as well as most other galaxies.

Candidates for the Black House

The nearest black hole, or rather a candidate for the role of a BH, is an object (V616 Unicorn), which is located at a distance of 3000 light years from the Sun (in our galaxy). It consists of two components: a star with a mass of half the solar mass, as well as an invisible small body, the mass of which is 3-5 times the mass of the Sun. If this object turns out to be a small black hole of stellar mass, then by right it will be the nearest BH.

Following this object, the second closest black hole is the Cyg X-1 object, which was the first candidate for the role of a BH. The distance to it is approximately 6070 light years. It is well studied: it has a mass of 14.8 solar masses and an event horizon radius of about 26 km.

According to some sources, another closest candidate for the role of a BH may be a body in the star system V4641 Sagittarii (V4641 Sgr), which, according to 1999 estimates, was located at a distance of 1600 light years. However, subsequent studies increased this distance by at least 15 times.

How many black holes are there in our galaxy?

There is no exact answer to this question, since it is rather difficult to observe them, and for the entire time of the study of the sky, scientists have managed to find about a dozen black holes within the Milky Way. Without indulging in calculations, we note that in our galaxy there are about 100 - 400 billion stars, and approximately every thousandth star has enough mass to form a black hole. It is likely that millions of black holes could have formed during the existence of the Milky Way. Since it is easier to register huge black holes, it is logical to assume that most likely most BHs in our galaxy are not supermassive. It is noteworthy that NASA's 2005 studies suggest the presence of a swarm of black holes (10-20 thousand) orbiting the center of the galaxy. In addition, in 2016, Japanese astrophysicists discovered a massive satellite near the object * - a black hole, the core of the Milky Way. Due to the small radius (0.15 light years) of this body, as well as its huge mass (100,000 solar masses), scientists suggest that this object is also a supermassive black hole.

The nucleus of our galaxy, the black hole of the Milky Way (Sagittarius A *, Sgr A * or Sagittarius A *) is supermassive and has a mass of 4.31 10 6 solar masses, and a radius of 0.00071 light years (6.25 light years . or 6.75 billion km). The temperature of Sagittarius A * together with the cluster around it is about 1 · 10 7 K.

The largest black hole

The largest black hole in the Universe that scientists have managed to detect is a supermassive black hole, FSRQ blazar, in the center of galaxy S5 0014 + 81, at a distance of 1.2 · 10 10 light years from Earth. According to preliminary results of observation, using the Swift space observatory, the mass of the BH was 40 billion (40 · 10 9) solar masses, and the Schwarzschild radius of such a hole was 118.35 billion kilometers (0.013 light years). It is also estimated to have originated 12.1 billion years ago (1.6 billion years after the Big Bang). If this giant black hole does not absorb the surrounding matter, then it will survive to the era of black holes - one of the epochs of the development of the Universe, during which black holes will dominate in it. If the nucleus of the galaxy S5 0014 + 81 continues to grow, then it will become one of the last black holes that will exist in the Universe.

The other two known black holes, although they do not have their own names, are of the greatest importance for the study of black holes, since they confirmed their existence experimentally, and also gave important results for the study of gravity. We are talking about the event GW150914, which is called the collision of two black holes into one. This event made it possible to register.

Detecting black holes

Before considering methods for detecting BHs, one should answer the question - why is a black hole black? - the answer to it does not require deep knowledge in astrophysics and cosmology. The fact is that a black hole absorbs all radiation incident on it and does not emit at all, if you do not take into account the hypothetical. If we consider this phenomenon in more detail, we can assume that processes that lead to the release of energy in the form of electromagnetic radiation do not occur inside black holes. Then, if the BH does radiate, then it is in the Hawking spectrum (which coincides with the spectrum of a heated, absolutely black body). However, as mentioned earlier, this radiation was not detected, which suggests a completely low temperature of black holes.

Another generally accepted theory says that electromagnetic radiation is not at all capable of leaving the event horizon. It is most likely that photons (light particles) are not attracted by massive objects, since, according to the theory, they themselves have no mass. However, the black hole still "attracts" photons of light by distorting space-time. If we imagine a BH in space as a kind of depression on the smooth surface of space-time, then there is a certain distance from the center of the black hole, approaching to which the light will no longer be able to move away. That is, roughly speaking, the light begins to “fall” into the “pit”, which does not even have a “bottom”.

In addition, if we take into account the effect of gravitational redshift, then perhaps in a black hole, light loses its frequency, shifting along the spectrum to the region of low-frequency long-wavelength radiation, until it loses energy at all.

So, a black hole is black and therefore difficult to detect in space.

Detection methods

Consider the methods astronomers use to detect a black hole:

In addition to the methods mentioned above, scientists often associate objects such as black holes and. Quasars are some kind of clusters of cosmic bodies and gas, which are one of the brightest astronomical objects in the Universe. Since they have a high intensity of luminescence at relatively small sizes, there is reason to assume that the center of these objects is a supermassive black hole, which attracts the surrounding matter. Due to such a powerful gravitational attraction, the attracted matter is so hot that it radiates intensely. The detection of such objects is usually compared to the detection of a black hole. Sometimes quasars can radiate in two directions jets of heated plasma - relativistic jets. The reasons for the appearance of such jets (jets) are not completely clear, however, they are probably caused by the interaction of the magnetic fields of the BH and the accretion disk, and are not emitted by the direct black hole.

Jet in the galaxy M87 striking from the center of the BH

Summing up the above, one can imagine, up close: it is a spherical black object, around which strongly heated matter revolves, forming a luminous accretion disk.

Merging and colliding black holes

One of the most interesting phenomena in astrophysics is the collision of black holes, which also makes it possible to detect such massive astronomical bodies. Such processes are of interest not only to astrophysicists, since they result in phenomena poorly studied by physicists. The clearest example is the previously mentioned event called GW150914, when two black holes approached so much that they merged into one as a result of mutual gravitational attraction. An important consequence of this collision was the emergence of gravitational waves.

According to the definition of gravitational waves, these are changes in the gravitational field that propagate in a wave-like manner from massive moving objects. When two such objects approach each other, they begin to revolve around a common center of gravity. As they approach each other, their rotation around their own axis increases. Such variable fluctuations of the gravitational field at some point can form one powerful gravitational wave, which can propagate in space for millions of light years. So at a distance of 1.3 billion light years, two black holes collided, forming a powerful gravitational wave, which reached the Earth on September 14, 2015 and was recorded by the LIGO and VIRGO detectors.

How do black holes die?

Obviously, for a black hole to cease to exist, it will need to lose all of its mass. However, according to its definition, nothing can leave the limits of a black hole if it has crossed its event horizon. It is known that the Soviet theoretical physicist Vladimir Gribov was the first to mention the possibility of emission of particles by a black hole in his discussion with another Soviet scientist Yakov Zeldovich. He argued that from the point of view of quantum mechanics, a black hole is capable of emitting particles through the tunneling effect. Later, with the help of quantum mechanics, the English theoretical physicist Stephen Hawking built his own, somewhat different theory. You can read more about this phenomenon. In short, in a vacuum there are so-called virtual particles, which are constantly born in pairs and annihilate with each other, while not interacting with the surrounding world. But if such pairs appear on the event horizon of a black hole, then strong gravity is hypothetically capable of separating them, with one particle falling inside the BH, and the other going away from the black hole. And since a particle that has escaped from the hole can be observed, and therefore has positive energies, the particle that has fallen into the hole must have negative energies. Thus, the black hole will lose its energy and there will be an effect called the evaporation of the black hole.

According to the available models of a black hole, as mentioned earlier, as its mass decreases, its radiation becomes more and more intense. Then, at the final stage of the existence of a BH, when it may decrease to the size of a quantum black hole, it will release a huge amount of energy in the form of radiation, which may be equivalent to thousands or even millions of atomic bombs. This event is somewhat reminiscent of the explosion of a black hole, like the same bomb. According to calculations, as a result of the Big Bang, primordial black holes could have arisen, and those of them, whose mass is about 10 12 kg, should have evaporated and exploded around our time. Be that as it may, such explosions have never been noticed by astronomers.

Despite Hawking's proposed mechanism for destroying black holes, the properties of Hawking's radiation cause a paradox in the framework of quantum mechanics. If a black hole absorbs some body, and then loses the mass resulting from the absorption of this body, then regardless of the nature of the body, the black hole will not differ from what it was before the absorption of the body. In this case, information about the body is forever lost. From the point of view of theoretical calculations, the transformation of the initial pure state into the obtained mixed ("thermal") state does not correspond to the current theory of quantum mechanics. This paradox is sometimes called the disappearance of information in a black hole. A definitive solution to this paradox has never been found. Known options for solving the paradox:

Inconsistency of Hawking's theory. This entails the impossibility of the destruction of the black hole and its constant growth.
The presence of white holes. In this case, the absorbed information does not disappear, but is simply thrown out into another Universe.
Inconsistency of the generally accepted theory of quantum mechanics.

Unsolved problems of black hole physics

Apparently, what was described earlier, although black holes have been studied for a relatively long time, they still have many features, the mechanisms of which are still unknown to scientists.

In 1970, an English scientist formulated the so-called. "The principle of cosmic censorship" - "Nature abhors a naked singularity." This means that the singularity is formed only in places hidden from view, like the center of a black hole. However, this principle has not yet been proven. There are also theoretical calculations according to which a "naked" singularity can occur.
Nor has the “no hair theorem” been proven, according to which black holes have only three parameters.
A complete theory of the black hole magnetosphere has not been developed.
The nature and physics of gravitational singularity have not been studied.
It is not known for certain what happens at the final stage of the existence of a black hole, and what remains after its quantum decay.

Interesting facts about black holes

Summing up the above, there are several interesting and unusual features of the nature of black holes:

BHs have only three parameters: mass, electric charge, and angular momentum. As a result of such a small number of characteristics of this body, the theorem that asserts this is called the "no-hair theorem". This also gave rise to the phrase "a black hole has no hair", which means that two black holes are absolutely identical, their three parameters mentioned are the same.
The BH density can be less than the air density, and the temperature is close to absolute zero. From this, it can be assumed that the formation of a black hole occurs not due to the compression of matter, but as a result of the accumulation of a large amount of matter in a certain volume.
Time for bodies absorbed by the BH runs much slower than for an external observer. In addition, the absorbed bodies are significantly stretched inside the black hole, which was called by scientists - spaghettification.
There may be about a million black holes in our galaxy.
There is probably a supermassive black hole at the center of every galaxy.
In the future, according to the theoretical model, the universe will reach the so-called era of black holes, when black holes will become the dominant bodies in the universe.

On April 10, a group of astrophysicists from the Event Horizon Telescope project released the first ever snapshot of a black hole. These gigantic but invisible space objects are still some of the most mysterious and intriguing in our universe.

Read below

What is a black hole?

A black hole is an object (region in space-time) whose gravity is so great that it attracts all known objects, including those that move at the speed of light. The quanta of the light itself also cannot leave this region, so the black hole is invisible. You can only observe electromagnetic waves, radiation and distortions of space around the black hole. The published Event Horizon Telescope depicts the black hole's event horizon - the edge of a region of super-gravity, framed by an accretion disk - luminous matter that is "sucked in" by the hole.

The term "black hole" appeared in the middle of the XX century, it was introduced by the American theoretical physicist John Archibald Wheeler. He first used the term at a scientific conference in 1967.

However, assumptions about the existence of objects so massive that even light cannot overcome the force of their gravity were put forward back in the 18th century. The modern theory of black holes began to form within the framework of general relativity. Interestingly, Albert Einstein himself did not believe in the existence of black holes.

Where do black holes come from?

Scientists believe that black holes are of different origins. Massive stars become a black hole at the end of their life: over billions of years, the composition of gases and temperature in them change, which leads to an imbalance between the gravity of the star and the pressure of hot gases. Then the star collapses: its volume decreases, but, since the mass does not change, the density increases. A typical stellar mass black hole has a radius of 30 kilometers and a density of more than 200 million tons per cubic centimeter. For comparison: for the Earth to become a black hole, its radius must be 9 millimeters.

There is another type of black hole - supermassive black holes that form the nuclei of most galaxies. Their mass is a billion times the mass of stellar black holes. The origin of supermassive black holes is unknown, it is hypothesized that they were once stellar mass black holes that grew, devouring other stars.

There is also a controversial idea about the existence of primordial black holes, which could appear from the compression of any mass at the beginning of the universe. In addition, there is an assumption that very small black holes with a mass close to the mass of elementary particles are formed at the Large Hadron Collider. However, there is no confirmation of this version yet.

Will the black hole swallow our galaxy?

In the center of the Milky Way galaxy there is a black hole - Sagittarius A *. Its mass is four million times the mass of the Sun, and its size - 25 million kilometers - is approximately equal to the diameter of 18 suns. Such a scale has led some to wonder: is not a black hole threatening our entire galaxy? Not only science fiction writers have grounds for such assumptions: a few years ago, scientists reported about the galaxy W2246-0526, which is located 12.5 billion light years from our planet. According to the description of astronomers, located in the center of W2246-0526, a supermassive black hole is gradually tearing it apart, and the resulting radiation accelerates in all directions incandescent giant clouds of gas. Torn apart by a black hole, the galaxy glows brighter than 300 trillion suns.

However, our home galaxy is not threatened (at least in the short term). Most objects in the Milky Way, including the solar system, are too far from a black hole to sense its pull. In addition, “our” black hole does not suck in all the material, like a vacuum cleaner, but acts only as a gravitational anchor for a group of stars in orbit around it - like the Sun for planets.

However, even if we ever get beyond the event horizon of a black hole, then, most likely, we will not even notice it.

What happens if you "fall" into a black hole?

An object attracted by a black hole, most likely, will not be able to return from there. To overcome the gravity of a black hole, you need to develop a speed higher than the speed of light, but humanity does not yet know how to do this.

The gravitational field around the black hole is very strong and inhomogeneous, so all objects near it change shape and structure. The side of the object that is closer to the event horizon is attracted with more force and falls with greater acceleration, so the whole object stretches, becoming like macaroni. This phenomenon was described in his book "A Brief History of Time" by the famous theoretical physicist Stephen Hawking. Even before Hawking, astrophysicists called this phenomenon spaghettification.

If we describe spaghettification from the point of view of an astronaut who flew up to a black hole feet first, then the gravitational field will tighten his legs, and then stretch and tear the body, turning it into a stream of subatomic particles.

It is impossible to see a fall into a black hole from the outside, as it absorbs light. An outside observer will only see that an object approaching a black hole gradually slows down and then stops altogether. After that, the silhouette of the object will become more and more blurred, acquire a red color, and finally just disappear forever.

According to Stephen Hawking's assumption, all objects that are attracted by the black hole remain in the event horizon. From the theory of relativity, it follows that near a black hole, time slows down until it stops, so for someone who falls, the fall into the black hole itself may never occur.

What's inside?

For obvious reasons, there is no reliable answer to this question now. However, scientists agree that inside a black hole the laws of physics we are used to no longer work. According to one of the most exciting and exotic hypotheses, the space-time continuum around the black hole is distorted so much that a hole is formed in reality itself, which could be a portal to another universe - or the so-called wormhole.

Black holes: the most mysterious objects in the universe

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

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 a certain D. Michel (an English priest from Yorkshire, who is fond of astronomy at his leisure) in the distant 1783. According to his calculations, if ours is taken and compressed (in modern computer parlance - archived) to a radius of 3 km, such a large (simply enormous) force of gravity 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 the absence of light that takes place.

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

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

This is what a black hole looks like.

How black holes form in space

As we know from astrophysics, all stars (including our Sun) have some limited supply of fuel. And although the life of a star can last for billions of 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 with incredibly impressive dimensions usually turn into a black hole - due to the contraction of these very incredible sizes, a multiple increase in the mass and gravitational force of the newly formed black hole occurs, which turns into a kind of galactic vacuum cleaner - it absorbs everything and everyone around it.

A black hole engulfs a star.

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

But let's be frank with you - today, scientists still do not know all the intricacies of the formation of a black hole, undoubtedly, this is an extremely complex astrophysical process, which in itself can last for millions of years. Although it is possible to move in this direction, the discovery and subsequent study of the so-called intermediate black holes, that is, stars in a state of extinction, in which an active process of black hole formation 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 are there in the universe

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

Black hole theory

Despite the huge mass (which is hundreds of thousands of times the mass of our Sun) and the incredible force 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 theory of a black hole has found factual 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 its 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 don't even grow old have time. Although we will be truthful, if you were inside a black hole, you would hardly have survived, since the force of gravity there is such that any material object would simply be torn apart, not even into parts, into atoms.

But if you were even near a black hole, within the range of its gravitational field, then you too would have had a hard time, because the more you would resist 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. True, this only applies to holes of relatively small mass. The powerful gravity around them gives rise to pairs of particles and antiparticles, one of the pair is drawn in by the hole, and the second is expelled outward. Thus, the black hole emits hard antiparticles and gamma rays. This evaporation or radiation from a black hole was named after the scientist who discovered it - "Hawking radiation."

The largest black hole

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

NGC 3842 is the brightest galaxy in the constellation Leo, located 320 million light-years from us. At its center is a huge black hole weighing 9.7 billion solar masses.

NGC 4849 is a galaxy in the Coma cluster, at a distance of 335 million light years from us, and boasts 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 up 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 dwarf black hole discovered by scientists at the moment in terms of 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 was 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 a 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 can themselves generate new universes.
Black holes can evaporate over time. We wrote above that the English scientist Stephen Hawking discovered that black holes have the property of radiation, and after a 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 in surrounding space. Although this is only an assumption, a hypothesis.
Black holes slow down time and warp 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.

Discovery Channel Black Holes Video

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

When writing the article, I tried to make it as interesting, useful and high-quality as possible. I would be grateful for any feedback and constructive criticism in the form of comments to the article. Also, you can write your wish / question / suggestion to my mail [email protected] or Facebook, sincerely the author.

Of all the hypothetical objects in the universe predicted by scientific theories, black holes make the most eerie impression. And, although the assumptions about their existence began to be expressed almost a century and a half before Einstein's publication of general relativity, convincing evidence of the reality of their existence was obtained quite recently.

Let's start with how general relativity addresses the question of the nature of gravity. Newton's law of universal gravitation states that a force of mutual attraction acts between any two massive bodies in the Universe. Because of this gravitational attraction, the Earth revolves around the Sun. General relativity forces us to look at the Sun-Earth system differently. According to this theory, in the presence of such a massive celestial body as the Sun, space-time seems to be perforated under its weight, and the uniformity of its tissue is disturbed. Imagine an elastic trampoline with a heavy ball (for example, from a bowling alley) resting on it. The stretched fabric bends under its weight, creating a vacuum around it. In the same way, the Sun pushes space-time around it.

According to this picture, the Earth simply rolls around the formed funnel (except that a small ball rolling around a heavy one on a trampoline will inevitably lose speed and spiral closer to a large one). And what we habitually perceive as the force of gravity in our daily life is also nothing more than a change in the geometry of space-time, and not a force in Newtonian understanding. To date, no more successful explanation of the nature of gravity than the general theory of relativity gives us has not been invented.

Now imagine what happens if we - within the framework of the proposed picture - increase and increase the mass of a heavy ball without increasing its physical size? Being absolutely elastic, the funnel will deepen until its upper edges converge somewhere high above the completely heavy ball, and then it simply ceases to exist when viewed from the surface. In the real Universe, having accumulated sufficient mass and density of matter, the object slams a space-time trap around itself, the fabric of space-time closes, and it loses its connection with the rest of the Universe, becoming invisible to it. This is how a black hole appears.

Schwarzschild and his contemporaries believed that such strange space objects did not exist in nature. Einstein himself not only held this point of view, but also mistakenly believed that he had succeeded in substantiating his opinion mathematically.

In the 1930s, the young Indian astrophysicist Chandrasekhar proved that a star that spent nuclear fuel sheds its shell and turns into a slowly cooling white dwarf only if its mass is less than 1.4 times the mass of the Sun. Soon the American Fritz Zwicky guessed that supernova explosions produce extremely dense bodies of neutron matter; later Lev Landau came to the same conclusion. After the work of Chandrasekhar, it was obvious that only stars with a mass of more than 1.4 solar masses can undergo such an evolution. Therefore, a natural question arose - is there an upper mass limit for supernovae that leave behind neutron stars?

In the late 1930s, the future father of the American atomic bomb, Robert Oppenheimer, established that such a limit does exist and does not exceed a few solar masses. At that time it was not possible to give a more accurate assessment; it is now known that the masses of neutron stars must be in the range of 1.5-3 Ms. But even from the approximate calculations of Oppenheimer and his graduate student George Volkov, it followed that the most massive descendants of supernovae do not become neutron stars, but go into some other state. In 1939, Oppenheimer and Hartland Snyder, using an idealized model, proved that a massive collapsing star is contracting to its gravitational radius. From their formulas, it actually follows that the star does not stop there, but the co-authors refrained from such a radical conclusion.

09.07.1911 - 13.04.2008

The final answer was found in the second half of the 20th century through the efforts of a whole galaxy of brilliant theoretical physicists, including Soviet ones. It turned out that such a collapse always compresses the star "all the way", completely destroying its substance. As a result, a singularity arises, a "superconcentrate" of the gravitational field, closed in an infinitely small volume. For a stationary hole, this is a point, for a rotating one, a ring. The curvature of space-time and, consequently, the gravitational force near the singularity tends to infinity. At the end of 1967, the American physicist John Archibald Wheeler was the first to call such a final stellar collapse a black hole. The new term fell in love with physicists and delighted journalists who spread it around the world (although the French did not like it at first, since the expression trou noir suggested dubious associations).

The most important property of a black hole is that no matter what gets into it, it will not come back. This even applies to light, which is why black holes got their name: a body that absorbs all light falling on it and does not emit its own seems to be absolutely black. According to general relativity, if an object approaches the center of a black hole at a critical distance - this distance is called the Schwarzschild radius - it can never go back. (German astronomer Karl Schwarzschild (1873-1916) in the last years of his life, using the equations of Einstein's general theory of relativity, calculated the gravitational field around a mass of zero volume.) For the mass of the Sun, the Schwarzschild radius is 3 km, that is, to turn our The sun is in a black hole, you need to condense its entire mass to the size of a small town!

Inside the Schwarzschild radius, the theory predicts even stranger phenomena: all the matter of a black hole gathers into an infinitely small point of infinite density at its very center - mathematicians call such an object a singular perturbation. With an infinite density, any finite mass of matter, mathematically speaking, occupies zero spatial volume. Whether this phenomenon actually occurs inside a black hole, we, naturally, cannot experimentally check, since everything that has got inside the Schwarzschild radius does not come back.

Thus, not having the opportunity to "examine" a black hole in the traditional sense of the word "look", we, nevertheless, can detect its presence by indirect signs of the influence of its super-powerful and completely unusual gravitational field on the matter around it.

Supermassive black holes

At the center of our Milky Way and other galaxies is an incredibly massive black hole millions of times heavier than the Sun. These supermassive black holes (as they received this name) were discovered by observing the nature of the movement of interstellar gas near the centers of galaxies. The gases, judging by the observations, rotate at a close distance from the supermassive object, and simple calculations using the laws of Newtonian mechanics show that the object that attracts them, with a meager diameter, has a monstrous mass. Only a black hole can spin the interstellar gas in the center of the galaxy this way. In fact, astrophysicists have already found dozens of such massive black holes in the centers of neighboring galaxies, and strongly suspect that the center of any galaxy is a black hole.

Stellar mass black holes

According to our current ideas about the evolution of stars, when a star with a mass exceeding about 30 solar masses perishes in a supernova explosion, its outer shell scatters, and its inner layers rapidly collapse towards the center and form a black hole in place of the star that has used up its fuel reserves. It is practically impossible to detect a black hole of this origin isolated in interstellar space, since it is in a rarefied vacuum and does not manifest itself in any way in terms of gravitational interactions. However, if such a hole was part of a binary star system (two hot stars orbiting around their center of mass), the black hole will still exert a gravitational effect on its paired star. Astronomers today have more than a dozen candidates for this kind of stellar system, although there is no strong evidence for any of them.

In a binary system with a black hole in its composition, the substance of the "living" star will inevitably "flow" in the direction of the black hole. And the substance sucked out by the black hole will swirl when falling into the black hole in a spiral, disappearing when crossing the Schwarzschild radius. When approaching the fatal boundary, however, the substance sucked into the black hole's funnel will inevitably thicken and heat up due to the increase in collisions between the particles absorbed by the hole until it heats up to the energies of wave radiation in the X-ray range of the electromagnetic spectrum. Astronomers can measure the frequency of changes in the intensity of X-rays of this kind and calculate, comparing it with other available data, the approximate mass of an object "pulling" matter onto itself. If the mass of an object exceeds the Chandrasekhar limit (1.4 solar masses), this object cannot be a white dwarf, in which our star is destined to degenerate. In most of the identified cases of observation of such binary X-ray stars, a neutron star is a massive object. However, more than a dozen cases have already been counted when the only reasonable explanation is the presence of a black hole in a binary star system.

All other types of black holes are much more speculative and based solely on theoretical research - there is no experimental evidence of their existence at all. First, these are black mini-holes with a mass comparable to the mass of a mountain and compressed to the radius of a proton. The idea of their origin at the initial stage of the formation of the Universe immediately after the Big Bang was expressed by the English cosmologist Stephen Hawking (see The Hidden Principle of the Irreversibility of Time). Hawking suggested that mini-hole explosions could explain the truly mysterious phenomenon of chiseled gamma-ray bursts in the Universe. Secondly, some theories of elementary particles predict the existence in the Universe - at the micro-level - of a real sieve of black holes, which are a kind of foam from the wastes of the universe. The diameter of such micro-holes is supposedly about 10-33 cm - they are billions of times smaller than a proton. At the moment, we do not have any hopes for experimental verification of even the very fact of the existence of such black hole particles, let alone somehow investigating their properties.

And what happens to the observer if he suddenly finds himself on the other side of the gravitational radius, otherwise called the event horizon. This is where the most amazing property of black holes begins. It is not in vain that, speaking of black holes, we have always mentioned time, or rather space-time. According to Einstein's theory of relativity, the faster a body moves, the more its mass becomes, but the slower time begins to pass! At low speeds, under normal conditions, this effect is invisible, but if the body (spacecraft) moves at a speed close to the speed of light, then its mass increases, and time slows down! When the speed of the body is equal to the speed of light, the mass goes to infinity, and time stops! This is evidenced by rigorous mathematical formulas. Let's go back to the black hole. Imagine a fantastic situation where a spaceship with astronauts on board approaches the gravitational radius or event horizon. It is clear that the event horizon is so named because we can observe any events (generally observe something) only up to this border. That we are not able to observe this border. Nevertheless, being inside the spacecraft approaching the black hole, the astronauts will feel the same as before, because on their watch the time will run "normally". The spacecraft will calmly cross the event horizon and move on. But since its speed will be close to the speed of light, the spaceship will reach the center of the black hole, literally, in an instant.

And for an outside observer, the spacecraft will simply stop on the event horizon, and will stay there almost forever! This is the paradox of the colossal gravitation of black holes. A natural question is whether the astronauts who go to infinity according to the clock of an external observer will survive. No. And the point is not at all about the enormous gravitation, but about the tidal forces, which in such a small and massive body vary greatly at short distances. With the growth of an astronaut 1 m 70 cm, the tidal forces at his head will be much less than at his feet and he will simply be torn apart on the event horizon. So, we have basically figured out what black holes are, but so far we have been talking about black holes of stellar mass. Currently, astronomers have managed to find supermassive black holes, the mass of which can be a billion suns! Supermassive black holes do not differ in properties from their smaller counterparts. They are only much more massive and, as a rule, are located in the centers of galaxies - the stellar islands of the Universe. In the center of our Galaxy (Milky Way) there is also a supermassive black hole. The colossal mass of such black holes will make it possible to search for them not only in Our Galaxy, but also in the centers of distant galaxies located at a distance of millions and billions of light years from the Earth and the Sun. European and American scientists have conducted a global search for supermassive black holes, which, according to modern theoretical calculations, should be located in the center of each galaxy.

Modern technologies make it possible to detect the presence of these collapsars in neighboring galaxies, but very few of them have been detected. This means that either black holes are simply hiding in dense gas and dust clouds in the central part of galaxies, or they are located in more distant corners of the Universe. So, black holes can be detected by the X-ray radiation emitted during the accretion of matter on them, and in order to make a census of such sources, satellites with X-ray telescopes on board were launched into near-Earth comic space. While searching for X-ray sources, the space observatories Chandra and Rossi found that the sky is filled with background X-rays and is millions of times brighter than visible light. Much of this background X-ray radiation from the sky must come from black holes. Usually in astronomy they talk about three types of black holes. The first is black holes of stellar masses (about 10 solar masses). They are formed from massive stars when they run out of thermonuclear fuel. The second is supermassive black holes in the centers of galaxies (masses from one million to billions of the sun). And finally, the primordial black holes formed at the beginning of the life of the Universe, the masses of which are small (of the order of the mass of a large asteroid). Thus, a large range of possible black hole masses remains unfilled. But where are these holes? While filling the space with X-rays, they nevertheless do not want to show their true "face". But in order to build a clear theory of the relationship between background X-ray radiation and black holes, it is necessary to know their number. At the moment, space telescopes have managed to detect only a small number of supermassive black holes, the existence of which can be considered proven. Indirect signs allow us to bring the number of observed black holes responsible for background radiation to 15%. One has to assume that the rest of the supermassive black holes are simply hiding behind a thick layer of dust clouds that only transmit high-energy X-rays or are too far away to be detected by modern observing means.

Supermassive black hole (neighborhood) at the center of galaxy M87 (X-ray image). An ejection (jet) from the event horizon is visible. Image from the site www.college.ru/astronomy

Finding hidden black holes is one of the main tasks of modern X-ray astronomy. The latest breakthroughs in this area, associated with research with the Chandra and Rossi telescopes, nevertheless cover only the low-energy range of X-rays - approximately 2000-20,000 electron-volts (for comparison, the energy of optical radiation is about 2 electron-volts). volt). Essential amendments to these studies can be made by the European space telescope "Integral", which is able to penetrate into the still insufficiently studied area of X-ray radiation with an energy of 20,000-300,000 electron-volts. The importance of studying this type of X-rays is that although the X-ray background of the sky has a low energy, multiple peaks (points) of radiation with an energy of about 30,000 electron-volts appear against this background. Scientists are just opening the veil of the mystery of what gives rise to these peaks, and Integral is the first sufficiently sensitive telescope capable of finding such sources of X-rays. According to astronomers, high-energy beams give rise to the so-called Compton-thick objects, that is, supermassive black holes enveloped in a dusty shell. It is the Compton objects that are responsible for the 30,000 electron-volt X-ray peaks in the background radiation field.

But, continuing their research, scientists came to the conclusion that Compton objects make up only 10% of the number of black holes that should create high-energy peaks. This is a serious obstacle to the further development of the theory. So the missing X-rays are not coming from Compton-thick, but from ordinary supermassive black holes? Then what about the dust curtains for low energy X-rays? The answer seems to lie in the fact that many black holes (Compton objects) have had enough time to absorb all the gas and dust that enveloped them, but before that they had the opportunity to assert themselves with high-energy X-rays. After absorbing all the matter, such black holes were already unable to generate X-rays on the event horizon. It becomes clear why these black holes cannot be detected, and it becomes possible to attribute the missing sources of background radiation to their account, since although the black hole no longer emits, the radiation previously created by it continues its journey through the Universe. However, it is possible that the missing black holes are more hidden than astronomers assume, that is, the fact that we do not see them does not mean that they are not. We just don't have enough observing power to see them. Meanwhile, NASA scientists plan to expand the search for hidden black holes even further into the universe. It is there that the underwater part of the iceberg is located, they say. For several months, research will be carried out as part of the Swift mission. Penetration into the deep universe will reveal hidden black holes, find the missing link for background radiation and shed light on their activity in the early era of the universe.

Some black holes are considered more active than their quiet neighbors. Active black holes absorb the surrounding matter, and if a "gape" star flying past gets into the flight of gravity, then it will certainly be "eaten" in the most barbaric way (torn to shreds). The absorbed substance, falling on the black hole, heats up to enormous temperatures, and experiences a flash in the gamma, X-ray and ultraviolet ranges. There is also a supermassive black hole in the center of the Milky Way, but it is more difficult to study than holes in nearby or even distant galaxies. This is due to a dense wall of gas and dust that stands in the way of the center of our Galaxy, because the solar system is located almost at the edge of the galactic disk. Therefore, observing the activity of black holes is much more effective for those galaxies whose core is clearly visible. When observing one of the distant galaxies located in the constellation Bootes at a distance of 4 billion light years, astronomers for the first time managed to trace from the beginning and almost to the end the process of absorption of a star by a supermassive black hole. For thousands of years, this giant collapsar rested quietly in the center of an unnamed elliptical galaxy, until one of the stars dared to get close enough to it.

The black hole's powerful gravity tore the star apart. Clumps of matter began to fall onto the black hole and, upon reaching the event horizon, flare up brightly in the ultraviolet range. These flares were recorded by the new NASA space telescope Galaxy Evolution Explorer, which studies the sky in ultraviolet light. The telescope continues to observe the behavior of the distinguished object even today. the black hole's meal is not over yet, and the remains of the star continue to fall into the abyss of time and space. Observations of such processes, in the end, will help to better understand how black holes evolve with their parent galaxies (or, conversely, galaxies evolve with a parent black hole). Earlier observations show that such excesses are not uncommon in the universe. Scientists estimate that, on average, a star is absorbed by a supermassive black hole in a typical galaxy once every 10,000 years, but since there are a large number of galaxies, star absorption can be observed much more often.

a source

Mysterious and elusive black holes. The laws of physics confirm the possibility of their existence in the universe, but many questions still remain. Numerous observations show that holes exist in the universe and there are more than a million of these objects.

What are black holes?

Back in 1915, when solving Einstein's equations, such a phenomenon as "black holes" was predicted. However, the scientific community became interested in them only in 1967. They were then called "collapsed stars", "frozen stars".

Now a black hole is called a region of time and space, which have such gravity that even a ray of light cannot get out of it.

How do black holes form?

There are several theories of the appearance of black holes, which are divided into hypothetical and realistic. The simplest and most widespread realistic theory is the theory of gravitational callapse of large stars.

When a sufficiently massive star before "death" grows in size and becomes unstable, consuming the last fuel. At the same time, the mass of the star remains unchanged, but its size decreases as the so-called compaction occurs. In other words, during compaction, the heavy nucleus "falls" into itself. In parallel with this, the compaction leads to a sharp increase in temperature inside the star and the outer layers of the celestial body are torn off, from which new stars are formed. At the same time in the center of the star - the core falls into its own "center". As a result of the action of the forces of gravity, the center collapses into a point - that is, the forces of gravity are so strong that they absorb the compacted core. This is how a black hole is born, which begins to distort space and time, so that even light cannot escape from it.

There is a supermassive black hole at the centers of all galaxies. According to Einstein's theory of relativity:

"Any mass distorts space and time."

Now imagine how much a black hole distorts time and space, because its mass is huge and at the same time squeezed into an ultra-small volume. This ability creates the following oddity:

“Black holes have the ability to practically stop time and compress space. Because of this extreme distortion, the holes become invisible to us. "

If black holes are not visible, how do we know they exist?

Yes, even though the black hole is invisible, but it should be noticeable due to the matter that falls into it. As well as stellar gas, which is attracted by the black hole, when approaching the event horizon, the gas temperature begins to rise to ultra-high values, which leads to a glow. This is why black holes glow. Thanks to this, albeit weak glow, astronomers and astrophysicists explain the presence in the center of the galaxy of an object with a small volume, but a huge mass. At the moment, as a result of observations, about 1000 objects have been discovered that are similar in behavior to black holes.

Black holes and galaxies

How can black holes affect galaxies? This question plagues scientists around the world. There is a hypothesis according to which it is the black holes in the center of the galaxy that affect its shape and evolution. And that when two galaxies collide, black holes merge and during this process such a huge amount of energy and matter is ejected that new stars are formed.

Types of black holes

According to the existing theory, there are three types of black holes: stellar, supermassive, miniature. And each of them was formed in a special way.
- Black holes of stellar masses, it grows to huge sizes and collapses.
- Supermassive black holes, which can have a mass equivalent to millions of Suns, most likely exist in the centers of almost all galaxies, including our Milky Way. Scientists still have different hypotheses for the formation of supermassive black holes. So far, only one thing is known - supermassive black holes are a by-product of the formation of galaxies. Supermassive black holes - they differ from ordinary ones in that they are very large in size, but paradoxically low in density.
- No one has yet been able to detect a miniature black hole that would have a mass less than the Sun. It is possible that miniature holes could have formed soon after the "Big Bang", which is the initial exact existence of our universe (about 13.7 billion years ago).
- More recently, a new concept has been introduced as "white black holes". This is still a hypothetical black hole, which is the opposite of a black hole. Stephen Hawking actively studied the possibility of the existence of white holes.
- Quantum black holes - they exist only in theory so far. Quantum black holes can form when ultra-small particles collide in a nuclear reaction.
- Primordial black holes are also a theory. They were formed immediately after emergence.

At the moment, there are many open questions that future generations have yet to answer. For example, can there really be so-called "wormholes" with which you can travel through space and time. What exactly happens inside a black hole and what laws do these phenomena obey. And what about the disappearance of information in a black hole?