Both for scientists of past centuries and for researchers of our time, the greatest mystery of the cosmos is the black hole. What's inside this completely unfamiliar system to physics? What laws apply there? How does time pass in a black hole, and why can’t even light quanta escape from there? Now we will try, of course, from the point of view of theory and not practice, to understand what is inside a black hole, why it, in principle, was formed and exists, how it attracts the objects that surround it.
First, let's describe this object
So, a black hole is a certain region of space in the Universe. It is impossible to isolate it as a separate star or planet, since it is not solid and not gas body. Without a basic understanding of what spacetime is and how these dimensions can change, it is impossible to comprehend what is inside a black hole. The point is that this area is not just a spatial unit. which distorts both the three dimensions we know (length, width and height) and the timeline. Scientists are confident that in the horizon region (the so-called area surrounding the hole), time takes on a spatial meaning and can move both forward and backward.
Let's learn the secrets of gravity
If we want to understand what's inside a black hole, let's take a closer look at what gravity is. It is this phenomenon that is key in understanding the nature of the so-called “wormholes”, from which even light cannot escape. Gravity is the interaction between all bodies that have a material basis. The strength of such gravity depends on the molecular composition of bodies, on the concentration of atoms, as well as on their composition. The more particles collapse in a certain area of space, the more gravitational force. This is inextricably linked with Theory big bang, when our Universe was the size of a pea. This was a state of maximum singularity, and as a result of a flash of light quanta, space began to expand due to the fact that particles repelled each other. Scientists describe a black hole exactly the opposite. What is inside such a thing in accordance with the TBZ? A singularity that is equal to the indicators inherent in our Universe at the moment of its birth.
How does matter get into a wormhole?
There is an opinion that a person will never be able to understand what is happening inside a black hole. Because once there, he will be literally crushed by gravity and the force of gravity. In fact, this is not entirely true. Yes, indeed, a black hole is a region of singularity where everything is compressed to the maximum. But this is not at all a “space vacuum cleaner” that can suck in all the planets and stars. Any material object, which finds itself on the event horizon, will observe a strong distortion of space and time (for now, these units stand separately). The Euclidean system of geometry will begin to malfunction, in other words, they will intersect, and the outlines of stereometric figures will no longer be familiar. As for time, it will gradually slow down. The closer you get to the hole, the slower the clock will move relative to Earth time, but you won't notice it. When falling into a wormhole, the body will fall at zero speed, but this unit will be equal to infinity. curvature, which equates the infinite to zero, which finally stops time in the region of singularity.
Reaction to emitted light
The only object in space that attracts light is a black hole. What is inside it and in what form it is there is unknown, but it is believed that it is pitch darkness, which is impossible to imagine. Light quanta When they get there, they don’t just disappear. Their mass is multiplied by the mass of the singularity, which makes it even larger and increases it. Thus, if inside " wormhole“You turn on the flashlight to look around, it won’t glow. The emitted quanta will constantly multiply by the mass of the hole, and you, roughly speaking, will only worsen your situation.
Black holes at every step
As we have already figured out, the basis of formation is gravity, the magnitude of which there is millions of times greater than on Earth. An accurate idea of what a black hole is was given to the world by Karl Schwarzschild, who, in fact, discovered the very event horizon and the point of no return, and also established that zero in a state of singularity is equal to infinity. In his opinion, a black hole can form at any point in space. In this case, a certain material object having a spherical shape must reach gravitational radius. For example, the mass of our planet must fit into the volume of one pea in order to become a black hole. And the Sun should have a diameter of 5 kilometers with its mass - then its state will become singular.
The horizon for the formation of a new world
The laws of physics and geometry work perfectly on earth and in outer space, where space approaches a vacuum. But they completely lose their significance on the event horizon. That's why with mathematical point It is impossible to calculate from vision what is inside a black hole. The pictures that you can come up with if you bend space in accordance with our ideas about the world are probably far from the truth. It has only been established that time here turns into a spatial unit and, most likely, to existing measurements some more are added. This makes it possible to believe that inside a black hole (a photo, as you know, will not show this, since the light there eats itself) completely different worlds are formed. These Universes may be composed of antimatter, which is currently unknown to scientists. There are also versions that the sphere of no return is just a portal that leads either to another world or to other points in our Universe.
Birth and death
Much more than the existence of a black hole is its creation or disappearance. A sphere that distorts space-time, as we have already found out, is formed as a result of collapse. This could be the explosion of a large star, a collision of two or more bodies in space, and so on. But how did matter that could theoretically be touched become a domain of time distortion? The puzzle is a work in progress. But it is followed by a second question - why do such spheres of no return disappear? And if black holes evaporate, then why doesn’t that light and all the cosmic matter that they sucked in come out of them? When matter in the singularity zone begins to expand, gravity gradually decreases. As a result, the black hole simply dissolves, and ordinary vacuum outer space remains in its place. Another mystery follows from this - where did everything that got into it go?
Is gravity our key to a happy future?
Researchers are confident that the energy future of humanity can be shaped by a black hole. What is inside this system is still unknown, but it has been established that at the event horizon any matter is transformed into energy, but, of course, partially. For example, a person, finding himself near the point of no return, will give up 10 percent of his matter for processing into energy. This figure is simply colossal; it became a sensation among astronomers. The fact is that on Earth, only 0.7 percent of matter is converted into energy.
Black holes are the only ones cosmic bodies, capable of attracting light by gravitational force. They are also the largest objects in the Universe. We are unlikely to know what happens near their event horizon (known as the “point of no return”) anytime soon. These are the most mysterious places in our world, about which, despite decades of research, very little is still known. This article contains 10 facts that can be called the most intriguing.
Black holes do not suck matter into themselves
Many people imagine a black hole as a kind of “space vacuum cleaner”, drawing in the surrounding space. In fact, black holes are ordinary space 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 in, it would rotate in the same orbit as it does today. Stars located next to 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 use Einstein's theory of general relativity to prove the existence of a “point of no return.” Einstein himself did not think about black holes, although his theory predicts their existence.
Schwarzschild made his proposal in 1915, immediately after Einstein published his general theory of relativity. That's when the term "Schwarzschild radius" arose - this is a value that shows how much you would have to compress an object for it to become a black hole.
Theoretically, anything can become a black hole if compressed enough. The denser the object, the stronger the gravitational field it creates. For example, the Earth would become a black hole if it had the mass of an object the size of a peanut.
Black holes can give birth to new universes
The idea that black holes can give birth to new universes seems absurd (especially since we are still not sure about the existence of other universes). Nevertheless, such theories are actively being developed by scientists.
A very simplified version of one of these theories is as follows. Our world has exclusively favorable conditions for life to appear in it. If any of physical constants changed even a little, we would not be in this world. Black hole singularity cancels ordinary laws physics and can (at least in theory) give rise to new universe, which will be different from ours.
Black holes can turn you (and anything else) into spaghetti
Black holes stretch objects that are near them. These items begin to resemble spaghetti (there is even a special term - “spaghettification”).
This happens due to the way gravity works. IN present moment your feet are closer to the center of the Earth than your head, so they are attracted more strongly. On the surface of a black hole, the difference in gravity begins to work against you. The legs are drawn towards the center of the black hole faster and faster, so that the upper half of the body cannot keep up with them. Result: spaghettification!
Black holes evaporate over time
Black holes not only absorb stellar wind, but also evaporate. This phenomenon was discovered in 1974 and was called Hawking radiation (after Stephen Hawking, who made the discovery).
Over time, the black hole can release all its mass into the surrounding space along with this radiation and disappear.
Black holes slow down time near them
As you approach the event horizon, time slows down. To understand why this happens, we need to look at the “twin paradox,” a thought experiment often used to illustrate the basic principles of Einstein's theory of general relativity.
One of the twin brothers remains on Earth, and the second flies to space travel, moving at the speed of light. A twin returning to Earth discovers that his brother has aged more than he has because, while traveling at close to the speed of light, time goes by slower.
As you approach the event horizon of a black hole, you will move at such a rate high speed that time will slow down for you.
Black holes are the most advanced energy systems
Black holes generate energy better than the Sun and other stars. This is due to the matter orbiting around them. Crossing the event horizon at enormous speed, matter in the orbit of a black hole heats up to extremely high temperatures. This is called black body radiation.
For comparison, when nuclear fusion 0.7% of matter is converted into energy. Near a black hole, 10% of matter becomes energy!
Black holes bend the space around them
Space can be thought of as a stretched rubber plate with lines drawn on it. If you put an object on the record, it will change its shape. Black holes work the same way. Their extreme mass attracts everything, including light (the rays of which, to continue the analogy, could be called lines on a plate).
Black holes limit the number of stars in the Universe
Stars arise from gas clouds. For star formation to begin, the cloud must cool.
The radiation from black bodies prevents gas clouds from cooling and prevents stars from appearing.
Theoretically, any object can become a black hole
The only difference between our Sun and a black hole is the force of gravity. At the center of a black hole it is much stronger 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 that exceed the Sun in mass by 20-30 times.
S. TRANKOVSKY
Among the most important and interesting problems modern physics and astrophysics, Academician V.L. Ginzburg named issues related to black holes (see “Science and Life” No. 11, 12, 1999). The existence of these strange objects was predicted more than two hundred years ago, the conditions leading to their formation were accurately calculated in the late 30s of the 20th century, and astrophysics took up them in earnest less than forty years ago. Today scientific journals Every year thousands of articles on black holes are published around the world.
The formation of a black hole can occur in three ways.
This is how it is customary to depict processes occurring in the vicinity of a collapsing black hole. Over time (Y), the space (X) around it (the shaded area) shrinks, rushing towards the singularity.
The gravitational field of a black hole introduces severe distortions into the geometry of space.
A black hole, invisible through a telescope, reveals itself only by its gravitational influence.
In the powerful gravitational field of a black hole, particle-antiparticle pairs are born.
The birth of a particle-antiparticle pair in the laboratory.
HOW THEY ARISE
Luminous celestial body, having density, equal density The Earth, and with a diameter two hundred and fifty times greater than the diameter of the Sun, due to the strength of its gravity, will not allow its light to reach us. Thus, it is possible that the largest luminous bodies in the Universe remain invisible precisely because of their size.
Pierre Simon Laplace.
Exposition of the world system. 1796
In 1783, the English mathematician John Mitchell, and thirteen years later, independently of him, the French astronomer and mathematician Pierre Simon Laplace, conducted a very strange study. They looked at the conditions under which light would be unable to escape the star.
The logic of the scientists was simple. For any astronomical object (planet or star), it is possible to calculate the so-called escape velocity, or the second cosmic velocity, which allows any body or particle to leave it forever. And in the physics of that time, Newton’s theory reigned supreme, according to which light is a stream of particles (before the theory electromagnetic waves and the quanta remained for almost a hundred and fifty years). The escape velocity of particles can be calculated based on the equality potential energy on the surface of the planet and kinetic energy body that "ran away" endlessly long distance. This speed is determined by the formula #1#
Where M- weight space object, R- its radius, G- gravitational constant.
From this we can easily obtain the radius of a body of a given mass (later called the “gravitational radius” r g "), at which the escape velocity is equal to the speed of light:
This means that a star compressed into a sphere with a radius r g< 2GM/c 2 will stop emitting - the light will not be able to leave it. A black hole will appear in the Universe.
It is easy to calculate that the Sun (its mass is 2.1033 g) will turn into a black hole if it contracts to a radius of approximately 3 kilometers. The density of its substance will reach 10 16 g/cm 3 . The radius of the Earth, compressed into a black hole, would decrease to about one centimeter.
It seemed incredible that there could be forces in nature capable of compressing a star to such an insignificant size. Therefore, the conclusions from the works of Mitchell and Laplace were considered for more than a hundred years to be something of a mathematical paradox that had no physical meaning.
Strict mathematical proof The fact that such an exotic object in space was possible was obtained only in 1916. The German astronomer Karl Schwarzschild, after analyzing the equations of Albert Einstein’s general theory of relativity, obtained interesting result. By studying the motion of a particle in a gravitational field massive body, he came to the conclusion: the equation loses physical meaning(its solution goes to infinity) when r= 0 and r = r g.
The points at which the characteristics of the field become meaningless are called singular, that is, special. Singularity in zero point reflects a point, or, what is the same thing, a centrally symmetrical structure of the field (after all, any spherical body - a star or a planet - can be represented as material point). And the points located on spherical surface radius r g, form the very surface from which the escape velocity is equal to the speed of light. In the general theory of relativity it is called the Schwarzschild singular sphere or the event horizon (why will become clear later).
Already based on the example of objects familiar to us - the Earth and the Sun - it is clear that black holes are very strange objects. Even astronomers who deal with matter at extreme values of temperature, density and pressure consider them very exotic, and until recently not everyone believed in their existence. However, the first indications of the possibility of the formation of black holes were already contained in A. Einstein’s general theory of relativity, created in 1915. The English astronomer Arthur Eddington, one of the first interpreters and popularizers of the theory of relativity, in the 30s derived a system of equations describing internal structure stars It follows from them that the star is in equilibrium under the influence of oppositely directed gravitational forces and internal pressure created by the movement of hot plasma particles inside the star and the pressure of radiation generated in its depths. This means that the star is a gas ball, in the center of which there is a high temperature, gradually decreasing towards the periphery. From the equations, in particular, it followed that the temperature of the surface of the Sun is about 5500 degrees (which was quite consistent with the data astronomical measurements), and at its center there should be about 10 million degrees. This allowed Eddington to make a prophetic conclusion: at this temperature, a thermonuclear reaction “ignites”, sufficient to ensure the glow of the Sun. Atomic physicists of that time did not agree with this. It seemed to them that it was too “cold” in the depths of the star: the temperature there was not enough for the reaction to “go.” To this the enraged theorist replied: “Look for a hotter place!”
And in the end, he turned out to be right: a thermonuclear reaction actually occurs in the center of the star (another thing is that the so-called “standard solar model", based on ideas about thermonuclear fusion, apparently turned out to be incorrect - see, for example, “Science and Life” No. 2, 3, 2000). But nevertheless, the reaction in the center of the star takes place, the star shines, and the radiation that arises keeps it in a stable state. But the nuclear “fuel” in the star burns out. The release of energy stops, the radiation goes out, and the restraining force gravitational attraction, disappears. There is a limit on the mass of a star, after which the star begins to shrink irreversibly. Calculations show that this happens if the mass of the star exceeds two to three solar masses.
GRAVITATIONAL COLLAPSE
At first, the rate of contraction of the star is small, but its rate continuously increases, since the force of gravity is inversely proportional to the square of the distance. The compression becomes irreversible; there are no forces capable of counteracting self-gravity. This process is called gravitational collapse. The speed of movement of the star's shell towards its center increases, approaching the speed of light. And here the effects of the theory of relativity begin to play a role.
The escape velocity was calculated based on Newtonian ideas about the nature of light. From the point of view of general relativity, phenomena in the vicinity of a collapsing star occur somewhat differently. In its powerful gravitational field, a so-called gravitational redshift occurs. This means that the frequency of radiation coming from a massive object is shifted towards lower frequencies. In the limit, at the boundary of the Schwarzschild sphere, the radiation frequency becomes equal to zero. That is, an observer located outside of it will not be able to find out anything about what is happening inside. That is why the Schwarzschild sphere is called the event horizon.
But decreasing the frequency equals slowing down time, and when the frequency becomes zero, time stops. This means that an outside observer will see a very strange picture: the shell of a star, falling with increasing acceleration, stops instead of reaching the speed of light. From his point of view, the compression will stop as soon as the size of the star approaches gravitational
usu. He will never see even one particle “dive” under the Schwarzschiel sphere. But for a hypothetical observer falling into a black hole, everything will be over in a matter of moments on his watch. Thus, the gravitational collapse time of a star the size of the Sun will be 29 minutes, and a much denser and more compact neutron star will take only 1/20,000 of a second. And here he faces trouble associated with the geometry of space-time near a black hole.
The observer finds himself in a curved space. Near the gravitational radius, gravitational forces become infinitely large; they stretch the rocket with the astronaut-observer into an infinitely thin thread infinite length. But he himself will not notice this: all his deformations will correspond to the distortions of space-time coordinates. These considerations, of course, refer to an ideal, hypothetical case. Any real body will be torn apart by tidal forces long before approaching the Schwarzschild sphere.
DIMENSIONS OF BLACK HOLES
The size of a black hole, or more precisely, the radius of the Schwarzschild sphere, is proportional to the mass of the star. And since astrophysics does not impose any restrictions on the size of a star, a black hole can be arbitrarily large. If, for example, it arose during the collapse of a star with a mass of 10 8 solar masses (or due to the merger of hundreds of thousands, or even millions of relatively small stars), its radius will be about 300 million kilometers, twice as large earth's orbit. A average density The substance of such a giant is close to the density of water.
Apparently, these are the kind of black holes that are found in the centers of galaxies. In any case, astronomers today count about fifty galaxies, in the centers of which, judging by indirect evidence (discussed below), there are black holes with a mass of about a billion (10 9) solar. Our Galaxy also apparently has its own black hole; Its mass was estimated quite accurately - 2.4. 10 6 ±10% of the mass of the Sun.
The theory suggests that along with such supergiants, black mini-holes with a mass of about 10 14 g and a radius of about 10 -12 cm (size atomic nucleus). They could appear in the first moments of the existence of the Universe as a manifestation of very strong inhomogeneity of space-time with a colossal energy density. Today, researchers realize the conditions that existed in the Universe at that time at powerful colliders (accelerators using colliding beams). Experiments at CERN earlier this year produced quark-gluon plasma, matter that existed before the creation of elementary particles. Research into this state of matter continues at Brookhaven, the American accelerator center. It is capable of accelerating particles to energies one and a half to two orders of magnitude higher than the accelerator in
CERN. The upcoming experiment has caused serious concern: will it create a mini-black hole that will bend our space and destroy the Earth?
This fear resonated so strongly that the US government was forced to convene an authoritative commission to examine this possibility. A commission consisting of prominent researchers concluded: the energy of the accelerator is too low for a black hole to arise (this experiment is described in the journal Science and Life, No. 3, 2000).
HOW TO SEE THE INVISIBLE
Black holes emit nothing, not even light. However, astronomers have learned to see them, or rather, to find “candidates” for this role. There are three ways to detect a black hole.
1. It is necessary to monitor the rotation of stars in clusters around a certain center of gravity. If it turns out that there is nothing in this center, and the stars seem to be spinning around empty space, we can say quite confidently: in this “emptiness” there is a black hole. It was on this basis that the presence of a black hole in the center of our Galaxy was assumed and its mass was estimated.
2. A black hole actively sucks matter into itself from the surrounding space. Interstellar dust, gas, and matter from nearby stars fall onto it in a spiral, forming a so-called accretion disk, similar to the ring of Saturn. (This is precisely the scarecrow in the Brookhaven experiment: a mini-black hole that appeared in the accelerator will begin to suck the Earth into itself, and this process could not be stopped by any force.) Approaching the Schwarzschild sphere, the particles experience acceleration and begin to emit in the X-ray range. This radiation has a characteristic spectrum similar to the well-studied radiation of particles accelerated in a synchrotron. And if such radiation comes from some region of the Universe, we can say with confidence that there must be a black hole there.
3. When two black holes merge, gravitational radiation occurs. It is calculated that if the mass of each is about ten solar masses, then when they merge in a matter of hours, energy equivalent to 1% of their total mass will be released in the form of gravitational waves. This is a thousand times more than the light, heat and other energy that the Sun emitted during its entire existence - five billion years. They hope to detect gravitational radiation with the help of gravitational wave observatories LIGO and others, which are now being built in America and Europe with the participation of Russian researchers (see “Science and Life” No. 5, 2000).
And yet, although astronomers have no doubts about the existence of black holes, no one dares to categorically assert that exactly one of them is located at a given point in space. Scientific ethics, the conscientiousness of the researcher requires obtaining an unambiguous answer to the question posed, which does not tolerate discrepancies. It is not enough to estimate the mass of an invisible object; you need to measure its radius and show that it does not exceed the Schwarzschild radius. And even within our Galaxy this problem is not yet solvable. That is why scientists show a certain restraint in reporting their discovery, and scientific journals are literally filled with reports of theoretical work and observations of effects that can shed light on their mystery.
However, black holes have one more property, theoretically predicted, which might make it possible to see them. But, however, under one condition: the mass of the black hole should be much less than the mass of the Sun.
A BLACK HOLE CAN ALSO BE “WHITE”
For a long time, black holes were considered the embodiment of darkness, objects that in a vacuum, in the absence of absorption of matter, emit nothing. However, in 1974, the famous English theorist Stephen Hawking showed that black holes can be assigned a temperature, and therefore should radiate.
According to ideas quantum mechanics, vacuum is not emptiness, but a kind of “foam of space-time,” a mishmash of virtual (unobservable in our world) particles. However, quantum energy fluctuations can “eject” a particle-antiparticle pair from the vacuum. For example, in the collision of two or three gamma quanta, an electron and a positron will appear as if out of thin air. This and similar phenomena have been repeatedly observed in laboratories.
It is quantum fluctuations that determine the radiation processes of black holes. If a pair of particles with energies E And -E (total energy pair is equal to zero), arises in the neighborhood of the Schwarzschild sphere, further fate particles will be different. They can annihilate almost immediately or go under the event horizon together. In this case, the state of the black hole will not change. But if only one particle goes below the horizon, the observer will register another, and it will seem to him that it was generated by a black hole. At the same time, a black hole that absorbed a particle with energy -E, will reduce your energy, and with energy E- will increase.
Hawking calculated the rates at which all these processes occur and came to the conclusion: the probability of absorption of particles with negative energy higher. This means that the black hole loses energy and mass - it evaporates. In addition, she radiates as absolutely black body with temperature T = 6 . 10 -8 M With / M kelvins, where M c - mass of the Sun (2.10 33 g), M- the mass of the black hole. This simple relationship shows that the temperature of a black hole with a mass six times that of the sun is equal to one hundred millionth of a degree. It is clear that such a cold body emits practically nothing, and all the above reasoning remains valid. Mini-holes are another matter. It is easy to see that with a mass of 10 14 -10 30 grams, they are heated to tens of thousands of degrees and white-hot! It should be noted right away, however, that there are no contradictions with the properties of black holes: this radiation is emitted by a layer above the Schwarzschild sphere, and not below it.
So, the black hole, which seemed to be an eternally frozen object, sooner or later disappears, evaporating. Moreover, as she “loses weight,” the rate of evaporation increases, but it still takes an extremely long time. It is estimated that mini-holes weighing 10 14 grams, which appeared immediately after the Big Bang 10-15 billion years ago, should evaporate completely by our time. On last stage life, their temperature reaches colossal values, so the products of evaporation should be particles extremely high energy. Perhaps they are the ones that generate widespread air showers in the Earth's atmosphere - EAS. In any case, the origin of particles of anomalously high energy is another important and interesting problem, which can be closely related to no less exciting questions in the physics of black holes.
Black holes, dark matter, dark matter... These are undoubtedly the strangest and mysterious objects in space. Their bizarre properties can challenge the laws of physics of the Universe and even nature existing reality. To understand what black holes are, scientists suggest “changing your focus,” learning to think outside the box and using a little imagination. Black holes are formed from supernuclei massive stars, which can be characterized as a region of space where a huge mass is concentrated in emptiness, and nothing, not even light, can escape gravitational attraction there. This is the area where the second escape velocity exceeds the speed of light: And the more massive the object of motion, the faster it must move in order to get rid of the force of its gravity. This is known as escape velocity.
Collier's Encyclopedia calls black holes a region in space that arises as a result of the complete gravitational collapse of matter, in which the gravitational attraction is so strong that neither matter, nor light, nor other information carriers can leave it. That's why inner part a black hole is not causally related to the rest of the universe; happening inside a black hole physical processes cannot influence processes outside of it. A black hole is surrounded by a surface with the property of a unidirectional membrane: matter and radiation freely fall through it into the black hole, but nothing can escape from there. This surface is called the “event horizon.”
History of discovery
Black holes predicted general theory relativity (the theory of gravity proposed by Einstein in 1915) and others, more modern theories gravity were mathematically substantiated by R. Oppenheimer and H. Snyder in 1939. But the properties of space and time in the vicinity of these objects turned out to be so unusual that astronomers and physicists did not take them seriously for 25 years. However astronomical discoveries in the mid-1960s made one look at black holes as a possible physical reality. New discoveries and studies could fundamentally change our understanding of space and time, shedding light on billions of cosmic mysteries.
Formation of black holes
While in the bowels of the star there are thermonuclear reactions, they support high temperature and pressure, preventing the star from collapsing under its own gravity. However, over time, the nuclear fuel is depleted, and the star begins to shrink. Calculations show that if the mass of a star does not exceed three masses of the Sun, then it will win the “battle with gravity”: its gravitational collapse will be stopped by the pressure of the “degenerate” matter, and the star will forever turn into a white dwarf or neutron star. But if the mass of the star is more than three solar, then nothing can stop its catastrophic collapse and it will quickly go under the event horizon, becoming a black hole.
Is a black hole a donut hole?
What does not emit light is not easy to notice. One way to search for a black hole is to look for areas in outer space that have large mass and are in a dark space. When searching for these types of objects, astronomers found them in two main areas: in the centers of galaxies and in binaries. star systems of our Galaxy. In total, as scientists suggest, there are tens of millions of such objects.
Currently the only reliable way to distinguish black hole from an object of another type is to measure the mass and dimensions of the object and compare its radius with
Black holes are perhaps the most mysterious and enigmatic astronomical objects in our Universe; since their discovery, they have attracted the attention of scientists and excite the imagination of science fiction writers. What are black holes and what do they represent? Black holes are extinct stars, due to their physical features, possessing so much high density and such powerful gravity that even light cannot escape beyond them.
History of the discovery of black holes
For the first time, the theoretical existence of black holes, long before their actual discovery, was suggested by a certain D. Michel (an English priest from Yorkshire, who is interested in astronomy in his spare time) back in 1783. According to his calculations, if we take ours and compress it (in modern terms) computer language- archive) up to a radius of 3 km, such a large (simply enormous) gravitational force is formed that even light cannot leave it. This is how the concept of a “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. But it was only in 1967, through the efforts of the American astrophysicist John Wheeler, that the concept of black holes finally won a place in academic circles.
Be that as it may, D. Michel, 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, when they were first seen through a telescope.
This is what a black hole looks like.
How black holes form in space
As we know from astrophysics, all stars (including our Sun) have some limited supply of fuel. And although the life of a star can last billions of light years, sooner or later this conditional supply of fuel comes to an end, and the star “goes out”. The process of a star’s “fading” is accompanied by intense reactions, during which the star undergoes a significant transformation and, depending on its size, can turn into white dwarf, a neutron star or a black hole. Moreover, the largest stars, with incredibly impressive sizes, usually turn into a black hole - due to the compression of these most incredible sizes, there is a multiple increase in the mass and gravitational force of the newly formed black hole, which turns into a kind of galactic vacuum cleaner - absorbing everything and everyone around it.
A black hole swallows a star.
A small remark - our Sun, by galactic standards, is not at all big star and after extinction, which will occur in about a few billion years, it will most likely 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 in itself can last millions of light years. Although it is possible to advance in this direction could be the discovery and subsequent study of the so-called intermediate black holes, that is, stars in a state of extinction, in which active process black hole formation. By the way, a similar star was discovered by astronomers in 2014 in the arm of a spiral galaxy.
How many black holes are there in the Universe?
According to the theories of modern scientists in our galaxy milky way There may be up to hundreds of millions of black holes. There may be no less of them in our neighboring galaxy, to which there is nothing to fly from our Milky Way - 2.5 million light years.
Black hole theory
Despite the enormous mass (which is hundreds of thousands of times greater than the mass of our Sun) and incredible strength gravity, seeing black holes through a telescope was not easy, because they do not emit light at all. Scientists managed to notice the black hole only at the moment of its “meal” - absorption of another star, at this moment 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, not allowing the surrounding space and time to remain in their usual state. Yes, you heard right, time inside a black hole passes many times slower than usual, and if you were there, then when you returned back (if you were so lucky, of course), you would be surprised to notice that centuries have passed on Earth, and you haven’t even grown old made it in time. Although let’s be honest, if you were inside a black hole, you would hardly survive, since the force of gravity there is such that any material object would simply be torn apart, not even into pieces, into atoms.
But if you were even close to a black hole, within the influence of its gravitational field, you would also have a hard time, since the more you resist its gravity, trying to fly away, the faster you would fall into it. The reason for this seemingly paradox is the gravitational vortex field that all black holes possess.
What if a person falls into a black hole
Evaporation of black holes
English astronomer S. Hawking discovered an interesting fact: black holes also appear to emit evaporation. True, this only applies to holes of relatively small mass. The powerful gravity around them gives birth to pairs of particles and antiparticles, one of the pair is pulled in by the hole, and the second is expelled out. Thus, the black hole emits hard antiparticles and gamma-rays. This evaporation or radiation from a black hole was named after the scientist who discovered it - “Hawking radiation”.
The largest black hole
According to the black hole theory, at 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 discovered the two largest black holes known to date; they are located in two nearby galaxies: NGC 3842 and NGC 4849.
NGC 3842 is the brightest galaxy in the constellation Leo, located 320 million light years away from us. At its center there is a huge black hole weighing 9.7 billion solar masses.
NGC 4849, a galaxy in the Coma cluster, 335 million light-years away, boasts an equally impressive black hole.
The areas of influence of the gravitational field of these giant black holes, or speaking academic language, their event horizon, is approximately 5 times the distance from the Sun to! Such a black hole would eat our solar system and I wouldn’t even choke.
The smallest black hole
But in the vast family of black holes there are also very small representatives. Thus, the most dwarf black hole discovered by scientists at the moment is only 3 times the mass of our Sun. Essentially this theoretical minimum, necessary for the formation of a black hole, if that star were slightly 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 discovered that a black hole from one galaxy was being eaten by an even larger black glutton from another galaxy.
- According to the hypotheses of some scientists, black holes are not only galactic vacuum cleaners, sucking everything into themselves, but under certain circumstances they can themselves give birth to new universes.
- Black holes can evaporate over time. We wrote above that the English scientist Stephen Hawking discovered that black holes have the property of radiation and after some very long period of time, when there is nothing left to absorb around, the black hole will begin to evaporate more, until over time 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 under the conditions of a black hole will also 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 is known, 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
