Of all the objects known to mankind that are in outer space, black holes produce the most terrible and incomprehensible impression. This feeling covers almost every person at the mention of black holes, despite the fact that mankind has become aware of them for more than a century and a half. The first knowledge about these phenomena was obtained long before Einstein's publications on the theory of relativity. But the real confirmation of the existence of these objects was received not so long ago.
Of course, black holes are rightfully famous for their strange physical characteristics, which give rise to even more mysteries in the universe. They defy all cosmic laws of physics and cosmic mechanics with ease. In order to understand all the details and principles of the existence of such a phenomenon as a cosmic hole, we need to familiarize ourselves with modern achievements in astronomy and apply fantasy, in addition, you will have to go beyond standard concepts. For easier understanding and familiarization with space holes, the portal site has prepared a lot interesting information, which concerns these phenomena in the Universe.
Features of black holes from the portal website
First of all, it should be noted that black holes do not come from nowhere, they are formed from stars that have gigantic sizes and masses. Also, the biggest feature and uniqueness of every black hole is that they have a very strong gravitational pull. The force of attraction of objects to a black hole exceeds the second cosmic speed. Such indicators of gravity indicate that even rays of light cannot escape from the field of action of a black hole, since they have a much lower speed.
A feature of attraction can be called the fact that it attracts all objects that are in close proximity. The larger an object that passes in the vicinity of a black hole, the more influence and attraction it will receive. Accordingly, we can conclude that the larger the object, the stronger it is attracted by the black hole, and in order to avoid such an influence, the cosmic body must have very high speed indicators of movement.
It is also safe to say that in the entire Universe there is no such body that could avoid the attraction of a black hole, being in close proximity, since even the fastest light flux cannot avoid this influence. Einstein's theory of relativity is excellent for understanding the features of black holes. According to this theory, gravity is able to influence time and space distortion. It also says that the larger the object in outer space, the more it slows down time. In the vicinity of the black hole itself, time seems to stop altogether. When a spacecraft enters the field of action of a space hole, one could observe how it would slow down as it approached, and eventually disappear altogether.
You should not be very scared of phenomena such as black holes and believe all the unscientific information that can exist on this moment. First of all, we need to dispel the most common myth that black holes can suck in all the matter and objects around them, and in doing so they grow and absorb more and more. All this is not entirely true. Yes, indeed, they can absorb cosmic bodies and matter, but only those that are at a certain distance from the hole itself. Apart from their powerful gravity, they are not much different from ordinary stars with gigantic mass. Even when our Sun turns into a black hole, it will only be able to pull in objects located at a short distance, and all the planets will continue to rotate in their usual orbits.
Referring to the theory of relativity, we can conclude that all objects with strong gravity can affect the curvature of time and space. In addition, the greater the mass of the body, the stronger the distortion. So, quite recently, scientists managed to see this in practice, when it was possible to contemplate other objects that should have been inaccessible to our eyes due to huge cosmic bodies such as galaxies or black holes. All this is possible due to the fact that light rays passing near a black hole or another body are very strongly bent under the influence of their gravity. This type of distortion allows scientists to look much further into outer space. But with such studies it is very difficult to determine the real location of the body under study.
Black holes do not appear out of nowhere, they are formed as a result of the explosion of supermassive stars. Moreover, in order for a black hole to form, the mass of the exploded star must be at least ten times greater than the mass of the Sun. Each star exists due to thermonuclear reactions that take place inside the star. In this case, a hydrogen alloy is released during the fusion process, but it cannot leave the star's zone of influence, since its gravity attracts hydrogen back. This whole process is what allows the stars to exist. The synthesis of hydrogen and the gravity of a star are well-established mechanisms, but a violation of this balance can lead to an explosion of a star. In most cases, it is caused by the exhaustion of nuclear fuel.
Depending on the mass of the star, several scenarios of their development after the explosion are possible. So, massive stars form the field of a supernova explosion, and most of them remain behind the core of the former star, astronauts call such objects White Dwarfs. In most cases, a gas cloud forms around these bodies, which is held by the gravity of this dwarf. Another way of development of supermassive stars is also possible, in which the resulting black hole will very strongly attract all the matter of the star to its center, which will lead to its strong compression.
Such compressed bodies are referred to as neutron stars. In the most rare cases, after the explosion of a star, the formation of a black hole in our understanding of this phenomenon is possible. But for a hole to be created, the mass of the star must be simply gigantic. In this case, when the balance of nuclear reactions is disturbed, the gravity of the star simply goes crazy. At the same time, it begins to actively collapse, after which it becomes only a point in space. In other words, we can say that the star as a physical object ceases to exist. Despite the fact that it disappears, a black hole forms behind it with the same gravity and mass.
It is the collapse of stars that leads to the fact that they completely disappear, and in their place a black hole is formed with the same physical properties as the disappeared star. The difference is only a greater degree of compression of the hole than was the volume of the star. most main feature of all black holes is their singularity, which determines its center. This area opposes all the laws of physics, matter and space, which cease to exist. To understand the concept of singularity, we can say that this is a barrier, which is called the horizon of cosmic events. It is also the outer boundary of the black hole. The Singularity can be called the point of no return, since it is there that the giant gravitational force of the hole begins to act. Even the light that crosses this barrier is unable to escape.
The event horizon has such an attractive effect that it attracts all bodies at the speed of light, with the approach to the black hole itself, the speed indicators increase even more. That is why all objects that fall into the zone of action of this force are doomed to be sucked into the hole. It should be noted that such forces are capable of modifying a body that has fallen under the influence of such an attraction, after which they are stretched into a thin string, and then completely cease to exist in space.
The distance between the event horizon and the singularity can vary, this space is called the Schwarzschild radius. That is why the larger the size of the black hole, the greater will be the radius of action. For example, we can say that a black hole that would have the same mass as our Sun would have a Schwarzschild radius of three kilometers. Accordingly, large black holes have a greater radius of action.
The search for black holes is a rather difficult process, since light cannot escape from them. Therefore, the search and definition are based only on indirect evidence of their existence. The simplest method of finding them, which scientists use, is to search for them by finding places in a dark space if they have a large mass. In most cases, astronomers can find black holes in binary star systems or in the centers of galaxies.
Most astronomers tend to believe that there is also a super-powerful black hole at the center of our galaxy. This statement begs the question, can this hole swallow everything in our galaxy? In reality, this is impossible, since the hole itself has the same mass as the stars, because it is made from a star. Moreover, all the calculations of scientists do not portend any global events associated with this object. Moreover, for billions of years, the cosmic bodies of our galaxy will quietly rotate around this black hole without any changes. The evidence of the existence of a hole in the center of the Milky Way can be the X-ray waves recorded by scientists. And most astronomers tend to believe that black holes actively radiate them in large quantities.
Quite often, star systems consisting of two stars are common in our galaxy, and often one of them can become a black hole. In this version, the black hole absorbs all the bodies in its path, while the matter begins to rotate around it, due to which the so-called acceleration disk is formed. A feature can be called the fact that it increases the speed of rotation and approaches the center. It is the matter that enters the middle of the black hole and radiates x-rays, while the matter itself is destroyed.
Binary systems of stars are the very first candidates for the status of a black hole. In such systems, it is most easy to find a black hole, due to the volume visible star you can also calculate the indicators of an invisible brother. Currently, the very first candidate for the status of a black hole may be a star from the constellation Cygnus, which actively emits X-rays.
Drawing a conclusion from all of the above about black holes, we can say that they are not such a dangerous phenomenon, of course, in the case of close proximity, they are the most powerful objects in outer space due to the force of gravity. Therefore, we can say that they are not particularly different from other bodies, their main feature is a strong gravitational field.
Regarding the purpose of black holes, a huge number of theories have been proposed, among which there were even absurd ones. So, according to one of them, scientists believed that black holes can give rise to new galaxies. This theory is based on the fact that our world is a fairly favorable place for the origin of life, but if one of the factors changes, life would be impossible. Because of this, the singularity and features of the change physical properties in black holes can give rise to a completely new universe, which will be significantly different from ours. But this is only a theory and rather weak due to the fact that there is no evidence of such an effect of black holes.
As for black holes, not only can they absorb matter, but they can also evaporate. A similar phenomenon was proven several decades ago. This evaporation can cause the black hole to lose all its mass, and then disappear altogether.
All this is the smallest piece of information about black holes, which you can find on the portal site. We also have a huge amount of interesting information about other cosmic phenomena.
Of all the hypothetical objects in the universe predicted by scientific theories, black holes make the most eerie impression. And, although assumptions about their existence began to be expressed almost a century and a half before the publication by Einstein general theory relativity, convincing evidence of the reality of their existence has been obtained quite recently.
Let's start with how general relativity addresses the question of the nature of gravity. Law gravity Newton argues that between any two massive bodies in the universe there is a force of mutual attraction. Because of this gravitational pull, 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, as it were, collapses under its weight, and the uniformity of its fabric is disturbed. Imagine an elastic trampoline on which lies a heavy ball (for example, from a bowling alley). The stretched fabric sags under its weight, creating a rarefaction around. In the same way, the Sun pushes the space-time around itself.
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 towards a large one). And what we habitually perceive as the force of gravity in our Everyday life, is also nothing but a change in the geometry of space-time, and not a force in the Newtonian sense. To date, a 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 it physical dimensions? Being absolutely elastic, the funnel will deepen until its upper edges converge somewhere high above the completely heavier ball, and then it simply ceases to exist when viewed from the surface. In the real Universe, having accumulated a sufficient mass and density of matter, the object slams a space-time trap around itself, the fabric of space-time closes, and it loses contact with the rest of the Universe, becoming invisible to it. This is how a black hole is created.
Schwarzschild and his contemporaries believed that such strange space objects do not exist in nature. Einstein himself not only adhered to this point of view, but also mistakenly believed that he managed to substantiate his opinion mathematically.
In the 1930s, a young Indian astrophysicist, Chandrasekhar, proved that a star that has spent its nuclear fuel sheds its shell and turns into a slowly cooling white dwarf only if its mass is less than 1.4 solar masses. Soon, the American Fritz Zwicky guessed that extremely dense bodies of neutron matter arise in supernova explosions; Later, Lev Landau came to the same conclusion. After the work of Chandrasekhar, it was obvious that only stars with a mass greater than 1.4 solar masses could undergo such an evolution. Therefore, a natural question arose - is there an upper mass limit for supernovae that neutron stars leave behind?
In the late 1930s, the future father of the American atomic bomb, Robert Oppenheimer, established that such a limit does indeed exist and does not exceed several solar masses. It was not possible then to give a more precise assessment; it is now known that the masses of neutron stars must be in the range 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 proved in an idealized model that a massive collapsing star contracts to its gravitational radius. From their formulas, in fact, it 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 by the efforts of a galaxy of brilliant theoretical physicists, including Soviet ones. It turned out that such a collapse always compresses the star “up to the stop”, completely destroying its substance. As a result, a singularity arises, a "superconcentrate" of the gravitational field, closed in an infinitely small volume. For a fixed hole, this is a point, for a rotating hole, it is a ring. The curvature of space-time and, consequently, the force of gravity near the singularity tend to infinity. In late 1967, 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, because 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 applies even to light, which is why black holes get their name: a body that absorbs all the light that falls on it and does not emit its own appears completely 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) last years of his life, using the equations of Einstein's general theory of relativity, he 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 Sun into a black hole, you need to condense all of its mass to the size of a small town!
Inside the Schwarzschild radius, the theory predicts even stranger phenomena: all the matter in a black hole gathers into an infinitesimal point of infinite density at its very center - mathematicians call such an object a singular perturbation. At infinite density, any finite mass of matter, mathematically speaking, occupies zero spatial volume. Whether this phenomenon really occurs inside a black hole, we, of course, cannot experimentally verify, since everything that has fallen inside the Schwarzschild radius does not return back.
Thus, without being able to "view" a black hole in the traditional sense of the word "look", we can nevertheless 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 are called) 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, they 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 in this way. In fact, astrophysicists have already found dozens of such massive black holes at the centers of our neighboring galaxies, and they strongly suspect that the center of any galaxy is a black hole.
Black holes with stellar mass
According to our current understanding of the evolution of stars, when a star with a mass greater than about 30 solar masses dies in a supernova explosion, its outer shell flies apart, and the inner layers rapidly collapse towards the center and form a black hole in the place of the star that has used up its fuel reserves. It is practically impossible to identify 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 would still have a gravitational effect on its partner star. Astronomers today have more than a dozen candidates for the role of star systems of this kind, although rigorous evidence has not been obtained for any of them.
In a binary system with a black hole in its composition, the matter of a "living" star will inevitably "flow" in the direction of the black hole. And the matter sucked out by the black hole will spin in a spiral when falling into the black hole, disappearing when crossing the Schwarzschild radius. When approaching the fatal boundary, however, the matter sucked into the funnel of the black hole will inevitably condense and heat up due to more frequent collisions between the particles absorbed by the hole, until it is heated up to the energy of wave radiation in the X-ray range of the electromagnetic radiation spectrum. Astronomers can measure the frequency of this kind of X-ray intensity change and calculate, by 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, into which our luminary is destined to degenerate. In most cases of observed observations of such double X-ray stars, a neutron star is a massive object. However, there have been more than a dozen cases where 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 confirmation 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 big bang was expressed by the English cosmologist Stephen Hawking (see Hidden principle of time irreversibility). Hawking suggested that explosions of mini-holes could explain the really mysterious phenomenon of chiselled bursts of gamma rays in the universe. Second, some theories 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 garbage 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 even the very fact of the existence of such black hole-particles, not to mention the fact that at least somehow explore their properties.
And what will happen to the observer if he suddenly finds himself on the other side of the gravitational radius, otherwise called the event horizon. Here begins the most amazing property of black holes. Not in vain, 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 greater its mass becomes, but the slower time starts to go! At low speeds under normal conditions, this effect is imperceptible, but if the body ( spaceship) 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 turns to infinity, and time stops! This is evidenced by strict mathematical formulas. Let's go back to the black hole. Imagine a fantastic situation when a starship 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 (observe something in general) only up to this boundary. That we are not able to observe this border. However, being inside a ship approaching a black hole, the astronauts will feel the same as before, because. according to their watch, the time will go "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 spacecraft will reach the center of the black hole, literally, in an instant.
And for an external observer, the spacecraft will simply stop at the event horizon, and will stay there almost forever! Such is the paradox of the colossal gravity of black holes. The question is natural, but will the astronauts who go to infinity according to the clock of an external observer remain alive. No. And the point is not at all in the enormous gravitation, but in the tidal forces, which in such a small and massive body vary greatly at small distances. With the growth of an astronaut 1 m 70 cm tidal forces his head will be much smaller than his legs and he will simply be torn apart already on the event horizon. So, we have found out in general terms what black holes are, but so far we have been talking about black holes of stellar mass. Currently, astronomers have managed to detect 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 star islands of the Universe. There is also a supermassive black hole at the center of our Galaxy (the Milky Way). 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 conducted a global search for supermassive black holes, which, according to modern theoretical calculations, should be located at the center of every galaxy.
Modern technology makes it possible to detect the presence of these collapsars in neighboring galaxies, but very few have been found. This means that either black holes simply hide 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 X-rays 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 space. Searching for sources of X-rays, the Chandra and Rossi space observatories have discovered that the sky is filled with X-ray background radiation, and is millions of times brighter than in visible rays. Much of this background X-ray emission from the sky must come from black holes. Usually in astronomy they talk about three types of black holes. The first is stellar-mass black holes (about 10 solar masses). They form from massive stars when they run out of fusion fuel. The second is supermassive black holes at the centers of galaxies (masses from a million to billions of solar masses). 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? 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 connection between the background X-ray radiation and black holes, it is necessary to know their number. At the moment, space telescopes have been able to detect only a small number of supermassive black holes, the existence of which can be considered proven. Indirect evidence makes it possible to bring the number of observable black holes responsible for background radiation to 15%. We have to assume that the rest of the supermassive black holes are simply hiding behind a thick layer of dust clouds that only allow high-energy X-rays to pass through or are too far away for detection by modern means of observation.
Supermassive black hole (neighbourhood) at the center of the M87 galaxy (X-ray image). A jet is visible from the event horizon. Image from www.college.ru/astronomy
The search for hidden black holes is one of the main tasks of modern X-ray astronomy. The latest breakthroughs in this area, associated with research using the Chandra and Rossi telescopes, however, cover only the low-energy range of X-ray radiation - approximately 2000-20,000 electron volts (for comparison, the energy of optical radiation is about 2 electron volts). volt). Significant amendments to these studies can be made by the European space telescope Integral, which is able to penetrate into the still insufficiently studied region of X-ray radiation with an energy of 20,000-300,000 electron volts. Importance of learning this type 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 yet to unravel the mystery of what generates these peaks, and Integral is the first telescope sensitive enough to find such X-ray sources. According to astronomers, high-energy beams give rise to the so-called Compton-thick objects, that is, supermassive black holes shrouded in a dust shell. It is the Compton objects that are responsible for the X-ray peaks of 30,000 electron volts in the background radiation field.
But continuing their research, the 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. Does this mean that the missing X-rays are supplied not by Compton-thick, but by ordinary supermassive black holes? Then what about dust screens 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 declare themselves with high energy x-rays. After absorbing all the matter, such black holes were already unable to generate X-rays at 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 radiates, the radiation previously created by it continues to travel through the Universe. However, it's entirely possible that the missing black holes are more hidden than astronomers suggest, so just because we can't see them doesn't mean they don't exist. It's just that we don't have enough observational power to see them. Meanwhile, NASA scientists plan to extend the search for hidden black holes even further into the universe. It is there that the underwater part of the iceberg is located, they believe. Within a few months, research will be carried out as part of the Swift mission. Penetration into the deep Universe will reveal hiding black holes, find the missing link for the background radiation and shed light on their activity in the early era of the Universe.
Some black holes are thought to be more active than their quiet neighbors. Active black holes absorb the surrounding matter, and if a "gapless" star flying by gets into the flight of gravity, then it will certainly be "eaten" in the most barbaric way (torn to shreds). Absorbed matter, falling into a black hole, is heated to enormous temperatures, and experiences a flash in the gamma, x-ray and ultraviolet ranges. There is also a supermassive black hole at the center of the Milky Way, but it is more difficult to study than holes in neighboring or even distant galaxies. This is due to the dense wall of gas and dust that gets in the way of the center of our Galaxy, because solar system located almost on the edge of the galactic disk. Therefore, observations of black hole activity are much more effective for those galaxies whose core is clearly visible. When observing one of the distant galaxies, located in the constellation Boötes 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 gigantic collapser lay quietly at the center of an unnamed elliptical galaxy until one of the stars dared to get close enough to it.
The powerful gravity of the black hole tore the star apart. Clots of matter began to fall into the black hole and, upon reaching the event horizon, flared brightly in the ultraviolet range. These flares were captured by the new NASA Galaxy Evolution Explorer space telescope, which studies the sky in ultraviolet light. The telescope continues to observe the behavior of the distinguished object even today, because the black hole's meal is not over yet, and the remnants of the star continue to fall into the abyss of time and space. Observations of such processes will eventually 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 have calculated that, on average, a star is absorbed by a typical galaxy's supermassive black hole once every 10,000 years, but since there are a large number of galaxies, star absorption can be observed much more often.
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Due to the relatively recent rise in interest in making popular science films about space exploration, the modern viewer has heard a lot about such phenomena as the singularity, or black hole. However, films obviously do not reveal the full nature of these phenomena, and sometimes even distort the constructed scientific theories for greater effect. For this reason, the presentation of many modern people about these phenomena either completely superficially, or completely erroneously. One of the solutions to the problem that has arisen 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 a hypothetical massive body that has such a strong gravitational attraction that the second cosmic velocity for it would exceed the speed of light. The second cosmic velocity is the speed that a relatively small object would need to overcome the gravitational pull of a celestial body and leave the closed orbit around this body. According to his calculations, a body with the density of the Sun and with a radius of 500 solar radii will have on its surface a second cosmic velocity equal to the speed of light. In this case, even 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, the concept of a supermassive body proposed by Michell did not attract much interest until the work of Einstein. Recall that the latter defined the speed of light as the limiting speed of information transfer. In addition, Einstein expanded the theory of gravity for speeds close to the speed of light (). As a result, it was no longer relevant to apply the 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 Subramanyan Chandrasekhar, who created a fundamental monograph: “ mathematical theory black holes."
Thus, the solution of the Einstein equations is represented by four options for four possible types of black holes:
- Black hole 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 parameters of the body. The solution of the German physicist Karl Schwarzschild allows you to calculate the external gravitational field of a spherical massive body. A feature of the German scientist's concept of black holes is the presence of an event horizon and the one behind it. Schwarzschild also first calculated the gravitational radius, which received his name, which determines the radius of the sphere on which the event horizon would be located for a body with a given mass.
- A black hole without rotation with a charge - the Reisner-Nordström solution. A solution put forward in 1916-1918, taking into account the possible electric charge of a black hole. This charge cannot be arbitrarily large and is limited due to the resulting electrical repulsion. The latter must be compensated by gravitational attraction.
- A black hole with rotation and no charge - Kerr's solution (1963). A rotating Kerr black hole differs from a static one by the presence of the so-called ergosphere (read on about this and other components of a black hole).
- 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 black holes in nature have an insignificant charge.
The formation of a black hole
There are several theories about how a black hole is formed and appears, the most famous of which is the emergence of a star with sufficient mass as a result of gravitational collapse. Such 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 shrink into a superdense one. If the pressure of the gas of a neutron star cannot compensate for the gravitational forces, that is, the mass of the star overcomes the so-called. Oppenheimer-Volkov limit, then the collapse continues, as a result of which 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. In the case of insufficient internal pressure to compensate for the same gravitational forces, a black hole can arise.
Two other scenarios remain hypothetical:
- The occurrence of a black hole 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 experiments on colliders.
Structure and physics of black holes
The structure of a black hole according to Schwarzschild includes only two elements that were mentioned earlier: the singularity and the event horizon of a 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 most of the existing physical theories do not work inside it. Thus, the physics of the singularity remains a mystery to scientists today. black hole - this is a kind of border, crossing which, a physical object loses the ability to return back beyond it and unequivocally "fall" into the singularity of a black hole.
The structure of a black hole becomes somewhat more complicated in the case of the Kerr solution, namely, in the presence of BH rotation. Kerr's solution implies that the hole has an ergosphere. Ergosphere - a certain area located outside the event horizon, inside which all bodies move in the direction of rotation of the black hole. given 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 an accretion disk, which represents a rotating substance around massive bodies. If a static Schwarzschild black hole is represented as a black sphere, then the Kerry black hole, due to the presence of an ergosphere, has the shape of an oblate ellipsoid, in the form of which we often saw black holes in drawings, in old movies or video games.
- How much does a black hole weigh? - The greatest theoretical material on the appearance 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 black holes, hypothetically resulting from nuclear reactions at high energies, such as those at colliders. The mass of such quantum black holes, in other words "Planck black holes" is of the order of , namely 2 10 −5 g.
- Black hole size. 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, is about 2.95 km, then the minimum radius of a BH of 3 solar masses will be about nine kilometers. Such relatively small sizes do not fit in 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 about 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 masses greater than 105 solar masses. There is an interesting pattern according to which the more massive the black hole, the lower its density. In this case, a change in mass by 11 orders of magnitude entails 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 less than the density of gold. And black holes 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 a large number matter to some extent. In the case of quantum black holes, their density can be about 10 94 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 a completely black body, that is, a body that absorbs all incident radiation. The radiation spectrum of a black body depends only on its temperature, then the temperature of a black hole can be determined from the Hawking radiation spectrum. As mentioned above, this radiation is the more powerful, the smaller the black hole. 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 one to detect the indicated radiation. According to calculations, even the temperature of a hole with a mass on the order of the mass of the Sun is negligibly small (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 min.), Such BHs can emit energy of the order of ten million atomic bombs. But, fortunately, the creation of such hypothetical objects will require 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 is a CHD made of?
Another question worries both scientists and those who are simply fond of astrophysics - what does a black hole consist of? There is no single answer to this question, since it is not possible to look beyond the event horizon surrounding any black hole. In addition, as mentioned earlier, the 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 just a thin implicit border, once beyond which, the same cosmic bodies are irrevocably attracted towards the last main component of the black hole - 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, a black hole may consist of neutrons. If we follow the scenario of the occurrence of a black hole as a result of the compression of a star to a neutron star with its subsequent compression, 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 are compressed in such a way that electrons combine with protons, thereby forming neutrons. Such a reaction does indeed take place in nature, with the formation of a neutron, neutrino emission occurs. However, these are just guesses.
What happens if you fall into a black hole?
Falling into an astrophysical black hole leads to stretching of the body. Consider a hypothetical suicide astronaut heading into a black hole wearing nothing but a space suit, 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 back. At some point, the astronaut will reach a point (slightly behind the event horizon) where the deformation of his body will begin to occur. Since the gravitational field of a black hole is non-uniform 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 will probably decompose it into atoms, which, sooner or later, will reach a singularity. One can only guess what a person will feel in this situation. It is worth noting that the effect of stretching the body is inversely proportional to the mass of the black hole. That is, if a BH with the 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 “tolerate” such a deformation without losing their structure.
As you know, near massive objects, time flows more slowly, which means that time for a suicide astronaut will flow much more slowly than for earthlings. In that case, perhaps he will outlive not only his friends, but the Earth itself. Calculations will be required to determine how much time will slow down for an astronaut, but from the above it can be assumed that the astronaut will fall into the black hole very slowly and may simply 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 away from the observer, albeit almost imperceptibly, and his time flows 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, later in the radio frequency region, and as a result, the radiation will be completely elusive.
Despite what has been written 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 such a case, the falling spacecraft would retain its structure. A reasonable question arises - where does a 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 way in places of significant curvature of the latter - the Einstein-Rosen bridge or wormhole. For such a powerful curvature of space, bodies with a gigantic mass will be required, with the role of which black holes would perfectly cope.
The Einstein-Rosen Bridge is considered an impenetrable wormhole, as it is small and unstable.
A traversable wormhole is possible within the theory of black and white holes. Where the white hole is the output of information that fell into the 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 was proposed by American scientists Kip Thorne and his graduate student Mike Morris, which can be passable. However, as in the case of the Morris-Thorne wormhole, so 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 before that time there was already a lot of theoretical material on the nature of black holes, as well as many candidate objects for the role of a black hole. First of all, one should take into account the dimensions of the black hole, 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.
- Intermediate mass black holes. A conditional intermediate type of black holes that have increased due to the absorption of nearby objects, such as gas accumulations, a neighboring star (in systems of two stars) and other cosmic bodies.
- Supermassive black hole. Compact objects with 10 5 -10 10 solar masses. Distinctive properties of such BHs are paradoxically low density, as well as weak tidal forces, which were discussed earlier. It is this supermassive black hole at the center of our Milky Way galaxy (Sagittarius A*, Sgr A*), as well as most other galaxies.
Candidates for CHD
The nearest black hole, or rather a candidate for the role of a black hole, 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 solar masses. If this object turns out to be a small black hole of stellar mass, then by right it will be the nearest black hole.
Following this object, the second closest black hole is Cyg X-1 (Cyg X-1), which was the first candidate for the role of a black hole. The distance to it is approximately 6070 light years. Quite 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 black hole may be a body in the star system V4641 Sagittarii (V4641 Sgr), which, according to estimates in 1999, 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 in our galaxy?
There is no exact answer to this question, since it is rather difficult to observe them, and during the entire study of the sky, scientists managed to detect 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 about 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 of the BHs in our galaxy are not supermassive. It is noteworthy that NASA research in 2005 suggests the presence of a whole 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 core 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 hours or 6.75 billion km). The temperature of Sagittarius A* together with the cluster around it is about 1 10 7 K.
The biggest black hole
The largest black hole in the universe that scientists have been able to detect is a supermassive black hole, the FSRQ blazar, at the center of the galaxy S5 0014+81, at a distance of 1.2·10 10 light-years from Earth. According to preliminary results of observation, with the help of the Swift space observatory, the mass of the black hole 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). In addition, according to calculations, it arose 12.1 billion years ago (1.6 billion years after the Big Bang). If this giant black hole does not absorb the matter surrounding it, then it will live to see the era of black holes - one of the eras in the development of the Universe, during which black holes will dominate in it. If the core 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, though not named, have highest value 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 allowed to register .
Detection of black holes
Before considering methods for detecting black holes, 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 the radiation falling on it and does not radiate at all, if you do not take into account the hypothetical. If we consider this phenomenon in more detail, we can assume that there are no processes inside black holes that lead to the release of energy in the form of electromagnetic radiation. Then if the black hole radiates, 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 widely accepted theory is that electromagnetic radiation and is not able to leave the event horizon at all. 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" the photons of light through the distortion of space-time. If we imagine a black hole 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 which the light will no longer be able to move away from it. 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, it is possible that light in a black hole loses its frequency, shifting along the spectrum to the region of low-frequency long-wave radiation, until it loses energy altogether.
So, a black hole is black and therefore difficult to detect in space.
Detection methods
Consider the methods that 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 accumulations of cosmic bodies and gas, which are among the brightest astronomical objects in the Universe. Since they have a high intensity of luminescence at relatively small sizes, there is reason to believe that the center of these objects is a supermassive black hole, which attracts the surrounding matter to itself. Due to such a powerful gravitational attraction, the attracted matter is so heated that it radiates intensely. The detection of such objects is usually compared with the detection of a black hole. Sometimes quasars can radiate jets of heated plasma in two directions - relativistic jets. The reasons for the emergence of such jets (jet) are not completely clear, but they are probably caused by the interaction of the magnetic fields of the BH and the accretion disk, and are not emitted by a direct black hole.
A jet in the M87 galaxy hitting from the center of a black hole
Summing up the above, one can imagine, up close: it is a spherical black object, around which strongly heated matter rotates, 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, as a result of mutual gravitational attraction, they merged into one. 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 rotate around a common center of gravity. As they approach, they spin around own axis increases. Such variable oscillations of the gravitational field at some point can form one powerful gravitational wave that can propagate in space for millions of light years. So, at a distance of 1.3 billion light years, a collision of two black holes occurred, which formed a powerful gravitational wave that 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 would need to lose all of its mass. However, according to her definition, nothing can leave the black hole if it has crossed its event horizon. It is known that for the first time the Soviet theoretical physicist Vladimir Gribov mentioned 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 a tunnel effect. Later, with the help of quantum mechanics, he built his own, somewhat different theory, the English theoretical physicist Stephen Hawking. You can read more about this phenomenon. In short, there are so-called virtual particles in vacuum, which are constantly born in pairs and annihilate each other, while not interacting with the surrounding world. But if such pairs arise at the black hole's event horizon, then strong gravity is hypothetically able to separate them, with one particle falling into the black hole, and the other going away from the black hole. And since a particle that has flown away from a hole can be observed, and therefore has positive energy, a particle that has fallen into a hole must have negative energy. Thus, the black hole will lose its energy and there will be an effect called black hole evaporation.
According to the available models of a black hole, as mentioned earlier, as its mass decreases, its radiation becomes more intense. Then, at the final stage of the existence of a black hole, when it may be reduced to the size of a quantum black hole, it will release a huge amount of energy in the form of radiation, which can 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, primordial black holes could have been born as a result of the Big Bang, and those of them, the mass of which is on the order of 10 12 kg, should have evaporated and exploded around our time. Be that as it may, such explosions have never been seen by astronomers.
Despite the mechanism proposed by Hawking for the destruction of black holes, the properties of Hawking 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 resulting 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 real solution to this paradox has never been found. Known options for solving the paradox:
- Inconsistency of Hawking's theory. This entails the impossibility of destroying 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 problem of black hole physics
Judging by everything that was described earlier, black holes, although they have been studied for a relatively long time, still have many features, the mechanisms of which are still not known to scientists.
- In 1970, an English scientist formulated the so-called. "principle of cosmic censorship" - "Nature abhors the bare 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.
- The “no-hair theorem”, according to which black holes have only three parameters, has not been proven either.
- A complete theory of the black hole magnetosphere has not been developed.
- The nature and physics of the gravitational singularity has 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, we can highlight several interesting and unusual features of the nature of black holes:
- Black holes 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 stating this is called the "no-hair theorem". This is also where the phrase “a black hole has no hair” came from, which means that two black holes are absolutely identical, their three parameters mentioned are the same.
- The density of black holes can be less than the density of air, and the temperature is close to absolute zero. From this we can 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.
- Time for bodies absorbed by black holes goes much slower than for an external observer. In addition, the absorbed bodies are significantly stretched inside the black hole, which has been called spaghettification by scientists.
- 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.
Black holes are some of the strangest and most fascinating bodies in the universe. They are extremely dense objects. And they have such a strong gravitational attraction that not even light can escape from their monstrous embrace.
Albert Einstein first predicted the existence of black holes in 1916 in his general theory of relativity. The term "black hole" was coined in 1967 by American astronomer John Wheeler. It was first used in 1971.
There are three types of black holes: ordinary black holes, supermassive black holes, and intermediate black holes.
Ordinary black holes. Small but deadly
In 2014, astronomers discovered an object that turned out to be an intermediate-mass black hole. It is located in an arm of a spiral galaxy.
Black hole theory - how they work
Black holes are incredibly massive. But at the same time they occupy a small area of \u200b\u200bspace. There is a direct relationship between mass and gravity. This means that they have an extremely strong gravitational field. Virtually nothing can escape them. In classical physics, even light entering a black hole cannot leave it.
Such a strong attraction creates an observation problem when it comes to black holes. Scientists simply cannot "see" them the way they can see stars and other objects in space. To detect these objects, scientists rely on the radiation that is emitted when dust and gas are swallowed up by a black hole. , lying in the center of the galaxy, may be shrouded in dust and gas around them. This may block the observation of control emissions.
Sometimes, when matter moves towards a black hole, it ricochets out of the event horizon and flies out rather than being sucked in. Bright jets of material are created, moving at almost relativistic speeds. Although the black hole itself remains invisible, these powerful jets can be seen from great distances.
event horizon
Black holes have three "layers" - outer, event horizon and singularity.
The event horizon of a black hole is where light loses its ability to "escape". When a particle crosses the event horizon, it can no longer leave the black hole. At the event horizon, gravity is constant.
The inner region of a black hole, where its mass is contained, is known as a singularity. This is the only point in space-time where the mass of a black hole is concentrated.
According to the ideas classical mechanics and physics can't do anything. However, when quantum mechanics is added to the equation, things change a bit. IN quantum mechanics For every particle there is an antiparticle. It is a particle with the same mass and opposite electric charge. When they meet, the particle-antiparticle pair can annihilate.
If a particle-antiparticle pair is created outside the reach of the black hole's event horizon, one of the particles may fall into the black hole and the other be ejected. As a result, the mass of the black hole decreases. This process is called Hawking radiation. And the black hole can start to decay, which is rejected by classical mechanics.
Scientists are still working to come up with equations to understand how black holes work.
Shining light from binary black holes
In 2015, astronomers using the Laser Interferometer Gravitational Wave Observatory ( ) detected gravitational waves for the first time. Since then, several other similar incidents have been observed using this tool. Gravitational waves, seen by LIGO, arose from the merger of small black holes.
The LIGO observations also provide insight into the direction in which the black hole is spinning. When a pair of black holes spiral around each other, they can spin in the same direction. Or the directions of rotation can be completely different.
There are two theories about how binary black holes form. The first suggests that they formed at about the same time, from two stars. They could be born together and die at about the same time. Companion stars would have a similar direction of rotation. Therefore, the black holes they left behind would also rotate in a similar way.
According to the second model, black holes in a star cluster descend to its center and merge. These companions would have random spin orientations compared to each other. LIGO observations of black holes with different spin orientations provide stronger evidence for this formation theory.
Your death will come before you reach the singularity. A 2012 study suggests that will cause the event horizon to act like a wall of fire, instantly burning you to death.
Black holes don't "suck in". The suction is caused by something being pushed into a vacuum, which a massive black hole is definitely not. Instead, the objects just fall into them.
The first object thought to be a black hole is Cygnus X-1. From In 1971, scientists discovered radio emissions emanating from Cygnus X-1. A massive hidden object was discovered and identified as a black hole.
Cygnus X-1 was the subject of a 1974 friendly dispute between Stephen Hawking and theoretical physicist Kip Thorne. The latter claimed that this source was a black hole. In 1990, Hawking admitted defeat.
Miniature black holes could form immediately after. The rapidly expanding space may have compressed some of its regions into tiny, dense black holes. They were less massive than the Sun.
If a star passes too close to a black hole, it may be swallowed up by it. According to astronomers, Milky Way from 10 million to a billion black holes with masses about three times the mass of the Sun.
String theory suggests more types of massive giant black holes than conventional classical mechanics.
Black holes are amazing stuff for science fiction books and movies. The film relied heavily on the advice of theoretical physicist Kip Thorne. This allowed us to bring real science to the Hollywood product. In fact, the special effects work for the blockbuster has led to an improved scientific understanding of what distant worlds might look like when they are located near a rapidly spinning black hole.
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Black holes are the only cosmic bodies capable of attracting light by gravity. They are also the largest objects in the universe. We're not likely to know what's going on near their event horizon (known as the "point of no return") anytime soon. These are the most mysterious places of our world, about which, despite decades of research, very little is known so far. This article contains 10 facts that can be called the most intriguing.
Black holes don't suck in matter.
Many people think of a black hole as a kind of "cosmic vacuum cleaner" that draws in the surrounding space. In fact, black holes are ordinary cosmic objects that have an exceptionally strong gravitational field.
If a black hole of the same size arose in the place of the Sun, the Earth would not be pulled inward, it would rotate in the same orbit as it does today. Stars located near black holes lose part of their mass in the form of stellar wind (this happens during the existence of any star) and black holes absorb only this matter.
The existence of black holes was predicted by Karl Schwarzschild
Karl Schwarzschild was the first to apply Einstein's general theory of relativity to justify the existence of a "point of no return". Einstein himself did not think about black holes, although his theory makes it possible to predict their existence.
Schwarzschild made his suggestion in 1915, just after Einstein published his general theory of relativity. That's when the term "Schwarzschild radius" came about, a value that tells you how much you have to compress an object to make it a black hole.
Theoretically, anything can become a black hole, given enough compression. The denser the object, the stronger the gravitational field it creates. For example, the Earth would become a black hole if an object the size of a peanut had its mass.
Black holes can spawn new universes
The idea that black holes can spawn new universes seems absurd (especially since we are still not sure about the existence of other universes). Nevertheless, such theories are being actively developed by scientists.
A very simplified version of one of these theories is as follows. Our world has exceptionally favorable conditions for the emergence of life in it. If any of the physical constants changed even slightly, we would not be in this world. The singularity of black holes cancels ordinary laws physics and can (at least in theory) give rise to a new universe that will be different from ours.
Black holes can turn you (and anything) into spaghetti
Black holes stretch objects that are close to them. These objects begin to resemble spaghetti (there is even a special term - "spaghettiification").
This is due to the way gravity works. IN currently your feet are closer to the center of the earth than your head, so they are more strongly attracted. At the surface of a black hole, the difference in gravity starts to work against you. The legs are attracted to the center of the black hole faster and faster, so that the upper half of the torso cannot keep up with them. Result: spaghettification!
Black holes evaporate over time
Black holes not only absorb the stellar wind, but also evaporate. This phenomenon was discovered in 1974 and was named Hawking radiation (after Stephen Hawking, who made the discovery).
Over time, the black hole can give all its mass into the surrounding space along with this radiation and disappear.
Black holes slow down time around them
As you get closer to the event horizon, time slows down. To understand why this happens, one must turn to the "twin paradox," a thought experiment often used to illustrate the basic tenets of Einstein's general theory of relativity.
One of the twin brothers remains on Earth, while the other flies off on a space journey, moving at the speed of light. Returning to Earth, the twin finds that his brother has aged more than he, because when moving at a speed close to the speed of light, time passes more slowly.
As you approach the event horizon of a black hole, you will be moving at such a high speed that time will slow down for you.
Black holes are the most advanced power plants
Black holes generate energy better than the Sun and other stars. This is due to the matter revolving around them. Overcoming the event horizon at great speed, the matter in the orbit of a black hole is heated to extremely high temperatures. This is called blackbody radiation.
For comparison, during nuclear fusion, 0.7% of matter is converted into energy. Near a black hole, 10% of matter becomes energy!
Black holes warp space around them
Space can be thought of as a stretched rubber band with lines drawn on it. If you put an object on the plate, it will change its shape. Black holes work the same way. Their extreme mass attracts everything to itself, including light (the rays of which, continuing the analogy, could be called lines on a plate).
Black holes limit the number of stars in the universe
Stars arise from gas clouds. In order for star formation to begin, the cloud must cool.
Radiation from black bodies prevents gas clouds from cooling and prevents the formation of stars.
Theoretically, any object can become a black hole.
The only difference between our Sun and a black hole is the strength of gravity. It is much stronger at the center of a black hole than at the center of a star. If our Sun were compressed to about five kilometers in diameter, it could be a black hole.
Theoretically, anything can become a black hole. In practice, we know that black holes arise only as a result of the collapse of huge stars, exceeding the mass of the Sun by 20-30 times.
