Black hole: what's inside? Interesting facts and research. What is a black hole
January 24th, 2013
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 Einstein's publication of the general theory of 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. Newton's law of universal gravitation states 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 daily life is also nothing more than 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 its 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 cosmic 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 got 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. (The 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 into a black hole, you need to condense all 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 actually 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 mechanics of Newton 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 substance 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 radiation energies of waves 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 the Big Bang was proposed by the English cosmologist Stephen Hawking (see The 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. 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 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 an experimental verification of even the very fact of the existence of such black holes-particles, not to mention, to somehow investigate 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, the tidal forces at his head will be much less than at his feet, and he will simply be torn apart already at 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. The importance of studying this type of X-rays lies in the fact 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 the 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 the solar system is 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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Black holes are one of the strangest phenomena in the universe. In any case, at this stage of human development. This is an object with infinite mass and density, and hence attraction, beyond which even light cannot escape - therefore the hole is black. A supermassive black hole can pull an entire galaxy into itself and not choke, and beyond the event horizon, familiar physics begins to squeal and twist into a knot. On the other hand, black holes can become potential transition "burrows" from one node of space to another. The question is, how close can we get to a black hole, and will it be fraught with consequences?
The supermassive black hole Sagittarius A*, located at the center of our galaxy, not only sucks nearby objects, but also throws out powerful radio emission. Scientists have long tried to see these rays, but they were interfered with by the scattered light surrounding the hole. Finally, they were able to break through the light noise with the help of 13 telescopes, which combined into a single powerful system. Subsequently, they discovered interesting information about previously mysterious rays.
A few days ago, on March 14, one of the most outstanding physicists of our time left this world,
A black hole is a special region in space. This is a kind of accumulation of black matter, capable of drawing in and absorbing other objects of space. The phenomenon of black holes is still not . All available data are just theories and assumptions of scientific astronomers.
The name "black hole" was introduced by the scientist J.A. Wheeler in 1968 at Princeton University.
There is a theory that black holes are stars, but unusual, like neutron ones. A black hole is - - because it has a very high luminosity density and sends absolutely no radiation. Therefore, it is invisible neither in infrared, nor in x-rays, nor in radio rays.
This situation French astronomer P. Laplace still 150 years before black holes. According to his arguments, if it has a density equal to the density of the Earth, and a diameter 250 times greater than the diameter of the Sun, then it does not allow the rays of light to propagate through the Universe due to its gravity, and therefore remains invisible. Thus, it is assumed that black holes are the most powerful radiating objects in the universe, but they do not have a solid surface.
Properties of black holes
All alleged properties of black holes are based on the theory of relativity, derived in the 20th century by A. Einstein. Any traditional approach to the study of this phenomenon does not provide any convincing explanation for the phenomenon of black holes.
The main property of a black hole is the ability to bend time and space. Any moving object that has fallen into its gravitational field will inevitably be drawn inward, because. in this case, a dense gravitational vortex, a kind of funnel, appears around the object. At the same time, the concept of time is also transformed. Scientists, by calculation, still tend to conclude that black holes are not celestial bodies in the conventional sense. These are really some kind of holes, wormholes in time and space, capable of changing and compacting it.
A black hole is a closed region of space into which matter is compressed and from which nothing can escape, not even light.
According to the calculations of astronomers, with the powerful gravitational field that exists inside black holes, not a single object can remain unharmed. It will instantly be torn into billions of pieces before it even gets inside. However, this does not exclude the possibility of exchanging particles and information with their help. And if a black hole has a mass at least a billion times the mass of the Sun (supermassive), then it is theoretically possible for objects to move through it without being torn apart by gravity.
Of course, these are only theories, because the research of scientists is still too far from understanding what processes and possibilities hide black holes. It is possible that something similar could happen in the future.
Black holes - perhaps the most mysterious and enigmatic astronomical objects in our Universe, have attracted the attention of pundits and excite the imagination of science fiction writers since their discovery. What are black holes and what do they look like? Black holes are extinguished stars, due to their physical characteristics, which have such a high density and such powerful gravity that even light cannot escape from them.
The history of the discovery of black holes
For the first time, the theoretical existence of black holes, long before their actual discovery, was suggested by someone D. Michel (an English priest from Yorkshire, who is fond of astronomy at his leisure) back in 1783. According to his calculations, if we take ours and compress it (in modern computer language, archive it) to a radius of 3 km, such a large (just huge) gravitational force is formed that even light cannot leave it. This is how the concept of “black hole” appeared, although in fact it is not black at all, in our opinion, the term “dark hole” would be more appropriate, because it is precisely the absence of light that takes place.
Later, in 1918, the great scientist Albert Einstein wrote about the issue of black holes in the context of the theory of relativity. But only in 1967, through the efforts of the American astrophysicist John Wheeler, the concept of black holes finally won a place in academic circles.
Be that as it may, both D. Michel, and Albert Einstein, and John Wheeler in their works assumed only the theoretical existence of these mysterious celestial objects in outer space, however, the true discovery of black holes took place in 1971, it was then that they were first noticed in space. telescope.
This is what a black hole looks like.
How do black holes form in space?
As we know from astrophysics, all stars (including our Sun) have some limited amount of fuel. And although the life of a star can last billions of light years, sooner or later this conditional supply of fuel comes to an end, and the star “goes out”. The process of "extinction" of a star is accompanied by intense reactions, during which the star undergoes a significant transformation and, depending on its size, can turn into a white dwarf, a neutron star, or a black hole. Moreover, the largest stars, which have incredibly impressive dimensions, usually turn into a black hole - due to the compression of these most incredible sizes, 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 - absorbs everything and everything around it.
A black hole swallows a star.
A small note - our Sun, by galactic standards, is not at all a large star, and after fading, which will occur in about a few billion years, most likely it will not turn into a black hole.
But let's be honest with you - today, scientists do not yet know all the intricacies of the formation of a black hole, undoubtedly, this is an extremely complex astrophysical process, which itself can last millions of light years. Although it is possible to advance in this direction, the detection and subsequent study of the so-called intermediate black holes, that is, stars that are in a state of extinction, in which the active process of forming a black hole, is taking place. By the way, a similar star was discovered by astronomers in 2014 in the arm of a spiral galaxy.
How many black holes exist in the universe
According to the theories of modern scientists, there may be up to hundreds of millions of black holes in our Milky Way galaxy. There may be no less of them in the galaxy next to us, to which there is nothing to fly from our Milky Way - 2.5 million light years.
Theory of black holes
Despite the huge mass (which is hundreds of thousands of times greater than the mass of our Sun) and the incredible strength of gravity, it was not easy to see black holes through a telescope, because they do not emit light at all. Scientists managed to notice a black hole only at the moment of its "meal" - the absorption of another star, at this moment a characteristic radiation appears, which can already be observed. Thus, the black hole theory has found actual confirmation.
Properties of black holes
The main property of a black hole is its incredible gravitational fields, which do not allow the surrounding space and time to remain in their usual state. Yes, you heard right, time inside a black hole flows many times slower than usual, and if you were there, then returning back (if you were so lucky, of course) you would be surprised to notice that centuries have passed on Earth, and you won’t even grow old have time. Although let's be truthful, if you were inside a black hole, you would hardly have survived, since the gravitational force there is such that any material object would simply be torn apart, not even into parts, into atoms.
But if you were even close to a black hole, within the limits of its gravitational field, then you would also have a hard time, because the more you resisted its gravity, trying to fly away, the faster you would fall into it. The reason for this seemingly paradox is the gravitational vortex field, which all black holes possess.
What if a person falls into a black hole
Evaporation of black holes
The English astronomer S. Hawking discovered an interesting fact: black holes also, it turns out, emit evaporation. True, this applies only to holes of relatively small mass. The powerful gravity around them creates pairs of particles and antiparticles, one of the pair is pulled inward by the hole, and the second is ejected outward. Thus, a black hole radiates hard antiparticles and gamma rays. This evaporation or radiation from a black hole was named after the scientist who discovered it - "Hawking radiation".
The biggest black hole
According to the theory of black holes, in the center of almost all galaxies there are huge black holes with masses from several million to several billion solar masses. And relatively recently, scientists have discovered the two largest black holes known to date, they are in two nearby galaxies: NGC 3842 and NGC 4849.
NGC 3842 is the brightest galaxy in the constellation Leo, located at a distance of 320 million light-years from us. In the center of it there is a huge black hole with a mass of 9.7 billion solar masses.
NGC 4849 is a galaxy in the Coma cluster, 335 million light-years away, boasting an equally impressive black hole.
The zones of action of the gravitational field of these giant black holes, or in academic terms, their event horizon, is about 5 times the distance from the Sun to! Such a black hole would eat our solar system and not even choke.
The smallest black hole
But there are very small representatives in the vast family of black holes. So the most dwarf black hole discovered by scientists at the moment in its mass is only 3 times the mass of our Sun. In fact, this is the theoretical minimum necessary for the formation of a black hole, if that star were a little smaller, the hole would not have formed.
Black holes are cannibals
Yes, there is such a phenomenon, as we wrote above, black holes are a kind of "galactic vacuum cleaners" that absorb everything around them, including ... other black holes. Recently, astronomers have discovered that a black hole from one galaxy is being eaten by another large black glutton from another galaxy.
- According to the hypotheses of some scientists, black holes are not only galactic vacuum cleaners that suck everything into themselves, but under certain circumstances they themselves can generate new universes.
- Black holes can evaporate over time. We wrote above that it was discovered by the English scientist Stephen Hawking that black holes have the property of radiation and after some very long period of time, when there is nothing to absorb around, the black hole will begin to evaporate more, until eventually it gives up all its mass into surrounding space. Although this is only an assumption, a hypothesis.
- Black holes slow down time and bend space. We have already written about time dilation, but space in the conditions of a black hole will be completely curved.
- Black holes limit the number of stars in the universe. Namely, their gravitational fields prevent the cooling of gas clouds in space, from which, as you know, new stars are born.
Black holes on the Discovery Channel, video
And in conclusion, we offer you an interesting scientific documentary about black holes from the Discovery channel.
A black hole in physics is defined as a region in space-time, the gravitational attraction of which is so strong that even objects moving at the speed of light, including quanta of light itself, cannot leave it. The boundary of this region is called the event horizon, and its characteristic size is called the gravitational radius, which is called the Black Forest radius. Black holes are the most mysterious objects in the universe. They owe their unfortunate name to the American astrophysicist John Wheeler. It was he who in the popular lecture "Our Universe: Known and Unknown" in 1967 called these superdense bodies holes. Previously, such objects were called "collapsed stars" or "collapsers". But the term "black hole" has taken root, and it has become simply impossible to change it. There are two types of black holes in the Universe: 1 - supermassive black holes, the mass of which is millions of times greater than the mass of the Sun (it is believed that such objects are located in the centers of galaxies); 2 - less massive black holes that result from the compression of giant dying stars, their mass is more than three solar masses; as the star contracts, the matter becomes more and more compacted, and as a result, the object's gravity increases to such an extent that light cannot overcome it. Neither radiation nor matter can escape a black hole. Black holes are super-powerful gravitators.
The radius to which a star must shrink in order to turn into a black hole is called the gravitational radius. For black holes formed from stars, it is only a few tens of kilometers. In some pairs of binary stars, one of them is invisible to the most powerful telescope, but the mass of the invisible component in such a gravitational system turns out to be extremely large. Most likely, such objects are either neutron stars or black holes. Sometimes invisible components in such pairs rip matter off a normal star. In this case, the gas is separated from the outer layers of the visible star and falls into an unknown where - into an invisible black hole. But before falling into the hole, the gas emits electromagnetic waves of various wavelengths, including very short X-ray waves. Moreover, near a neutron star or a black hole, the gas becomes very hot and becomes a source of powerful high-energy electromagnetic radiation in the X-ray and gamma ranges. Such radiation does not pass through the earth's atmosphere, but it can be observed using space telescopes. One of the likely candidates for black holes is considered to be a powerful source of X-rays in the constellation Cygnus.