First, the good news: black holes can't kill you. The strange news is that the universe is quite possibly teeming with microscopic black holes that formed at the dawn of time, all hurtling through space like cosmic bullets.
Some of them can weigh as much as the Earth's satellite - the Moon, others - like asteroids. But, regardless of weight, most of them should be less than the spaces in this sentence.
It sounds like science fiction, which it could be. But perhaps things are not so simple.
Dark matter
Now astrophysicists are working to explain how most things in the universe are made. They know that roughly 80% of the universe is dark matter, which exerts a gravitational pull on the other 20% of "normal" matter. This dark matter has remained invisible to experiments for the past 80 years.
Devices installed in space and underground have been releasing dark matter particles for many years, but this has not yet brought any results. That is why researchers have come to the somewhat frightening conclusion that we are surrounded by countless black holes that formed 13.8 billion years ago. 
On the dark side of the spectrum particle matter, the range of possibilities narrows very quickly. This could lead to a crisis of science if the solution to this riddle is never found.
Hope for the existence of small black holes
To clarify this issue, it is worth noting that physicists do not put very much on the existence of an infinite number of small black holes. As previously reported, the leading hypothesis is that dark matter particles do exist. The problem is that this search turned out to be more difficult than expected.
Possible weight of miniature black holes
Scientists looking for these ancient black holes do think they are quite heavy, perhaps 20 to 100 times heavier than the mass of the Sun. This idea has gained more support since the recent groundbreaking detection of gravitational waves, which are formed after the collision of two black holes of an unusual size (30 times the mass of the Sun). 
If these small black holes are real, the heaviest of them would weigh less than the moon and be 0.25 millimeters in diameter. The same width has a human hair. In this case, very light holes, the weight of which is the same as that of asteroids, will have an apparent size smaller than that of an atom.
What is the event horizon
The reason for this phenomenon is that black holes are extremely dense. In fact, any piece of matter in the universe compressed tightly enough can collapse if it goes beyond the gravitational point of no return. This boundary is spherical and is called the event horizon. Even photons of light - the fastest things in the Universe - cannot go beyond its limits if they fall into it. 
Any black holes that are less than an asteroid's mass probably evaporated a long time ago due to Hawking's radiation - this is a fantastic operation of the laws of nature, which Stephen Hawking formulated in 1974.
Possible impact on Earth
But if tiny black holes do exist around us, how often do they move, and how might that affect us?
Asteroid-mass black holes, if made entirely of dark matter, can pass through the Earth once every 1,000 years or so and are very difficult to detect. But if one of them passed near the Earth, scientists would probably feel it. Although some experts are skeptical that black holes with the weight of an asteroid can be dangerous and can be felt. 
But what if a very heavy black hole, the weight of which is equal to the moon, were to pass close to the orbit of our planet? Of course, scientists would notice if such a black hole passed near the Earth, as it would affect the orbits of all our satellites. For example, it could ruin the GPS.
The good news is that the Earth can be affected by such black holes every 100 million years or so as they pass between its orbit and the Sun. But such an event is absurd and unlikely, although it would certainly cause havoc. Besides, such a black hole could definitely kill someone. 
However, the scariest scenario, at least for scientists, is what these super tiny black holes, which are virtually undetectable, will mean for science.
It is quite possible that there is no interaction between dark and ordinary matter, except through gravity. But if that's the case, then we're in trouble. Scientists will never be able to continue their experiments if there is something completely invisible to them.
As a result of gravitational collapse, it turned into black hole. After that black hole begins to suck gas from the surface of the hot star. The second type is much more massive black holes at the centers of galaxies. Their mass exceeds the mass of the Sun by billions of times. Again, falling on such black holes, the substance heats up and emits characteristic radiation, which eventually reaches Earth, we can find it ...
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Behavior is called a singularity, that is, an area in which not only physics, but also mathematics does not work. Journey black holes To some extent, the study of singularities can be considered physical in the framework of general relativity, especially in the light of recent results about the finite ... ordinary Universe, a singularity can exist only closed from us by the horizon, that is, in the form black holes. So, recently, in the course of a numerical analysis of different scenarios of gravitational collapse, it was found that ...
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Black holes, white dwarfs...
White holes, black dwarfs.
Paper boats floating in the bathroom
With blurry lines of starry Cyrillic.
We are intrigued by the secrets of the Third Planet
And the brain of Professor Dowell's Head,
Worlds that are warmed by another sun
AND...
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Particles can sometimes create tiny superdense formations, from which unstable or stable non-decaying particles can theoretically be born. black holes. Of course, in cosmic rays coming from the regions of the largest galactic cataclysms and continuously bombarding our earth, you can find particles with much higher energies than in any man-made accelerator, but the subtlety here is ...
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Black hole of consciousness
Captured as many events passing by us as possible. We are trying to grab them to let them through this black hole, it is filled with information, it processes it into the knowledge it needs. And it manifests itself, forcing us to work ... manifests itself in those events that are formed on earth for people, in events of an interstellar scale, all with the same goal of collecting information and forming connections with others black holes. It is possible that in black holes found in galaxies, such centers are concentrated. ...
In our Galaxy, astronomers have discovered a monstrous concentration of stars.
The color of stars, like human skin, is determined by how they are born. The hotter the star, the more doves it is. The colors of the stars represent all the colors of the rainbow. But the "death" of the stars reduces the entire palette of their colors to only two - white and black. This attempt will resemble an episode from a fairy tale Lewis Carroll "Alice Through the Looking Glass" in which the King asks Alice:
-Look at the road! Who do you see there?
"No one," said Alice.
- I would like such a vision! said the King with envy. - See Nobody! Yes, even at such a distance.
It is impossible to see black holes directly through a telescope or to capture them in a photograph, for the reason that due to strong gravity, nothing, not even light, can leave the limits of influence of black holes. True, this is true only for black holes that do not rotate or rotate very slowly.
How then can one prove the existence of such objects in the universe? And how to imagine what happens in the vicinity or inside black holes? This can be helped by theoretical concepts developed by scientists.
In addition, black holes do not exist in isolation from other bodies - they interact with dust, gas of interstellar space, with other stars of galaxies, and create a field of unusual structure in the surrounding area.
A bit of history
The history of black holes, which the American physicist K. Thorn called "monsters of the Universe", is very long, since their prediction was made by the French mathematician and astronomer P.S. Laplace back in 1795 in the book "Statement of the World System".
In it, the creator of the first scientific cosmogony of the planetary system wrote that "a luminous star with a density equal to the density of the Earth and diameters 250 times greater than the diameter of the Sun does not allow a single light beam to reach us because of its gravity; therefore, it is possible that the brightest celestial bodies in the universe turn out to be invisible for this reason.
But are there such bodies on the surface of which the second space velocity is equal to the speed of light? If so, then nothing can leave the gravitational field of such an object, because for this it is necessary to have a speed greater than the speed of light. This means that a black hole does not even let light out, which means that no one can see such an object from the outside! It turns out that a hole is formed in space, however, it is better not to fall into it!
Terrible association
Where did the strange term "black hole" come from? Something extremely unusual and not very pleasant is associated with its pronunciation in humans. The concept of "black hole" arose even before Laplace's reasoning in 1757 in Calcutta. The ruler of Bengal, Nawab Siraj - Uddaulah, wanted to use force to resolve the dispute with the British East India Company. The small garrison was unable to resist the 50,000-strong army of the Nawab, who lost thousands of lives due to the desperate resistance of the fort's defenders. A nightmare awaited the survivors: the ruler of Bengal ordered to push 146 prisoners into a 5 by 6 meter room. In 10 hours on the night of June 20-21, the hottest time in India, 123 captives died. This chamber, which has two small windows, was called the “black hole of Calcutta.” The objects of the Universe, representing, in particular, one of the final stages of the life of stars, were called “black hole” by the American astrophysicist J. Wheeler back in 1968. So what is too much in a celestial black hole?
The sun will turn white
What, then, in nature makes a star close in on itself, that is, to become an isolated object? The reason for the "disappearance" of the body for the outside world is the manifestation of gravitational forces. This force, while thermonuclear reactions are taking place inside the star, is opposed by the pressure of gas and radiation. But there is a limited amount of "fuel" in each star and there comes a time when it can no longer occur in it the conversion of hydrogen into helium. And then the decreasing pressure of the gas, which occurs due to the loss of energy by the star (after all, it continues to glow!) Is not able to resist the force of universal gravitation. The star is shrinking! Moreover, the dimensions of an object passing from one state to another are reduced by hundreds and thousands of times. It all depends on what the initial mass of the star is.
If the mass of the star does not exceed 1.4 solar masses, then the compression may stop due to the fact that helium gas resists it. The density of matter increases millions of times! One cubic centimeter of such a star contains hundreds of tons of matter. And at such densities, the matter behaves in a different way! Objects of this kind were called white dwarfs and they have been discovered for a long time: the satellite of the brightest star in the sky, Sirius, was even captured not far from it. White dwarfs can shine, cooling down, for many billions of years, turning into cold bodies that could be called black dwarfs.
Signals of "green" men
In the early 60s, almost everyone was excited by the discovery of astronomers - signals from space were discovered, which changed with strict periodicity. Not otherwise than some kind of civilization makes you aware of its existence. They were called “green” little men! But everything turned out to be much simpler - unusual little stars in space turned out to be small, about 15 kilometers in diameter, stars that rotated rapidly. And the lighthouse was associated with such an object! What kind of star was it? Astronomers remembered that in the early 1930s, our compatriot L.D. Landau predicted the existence of such objects - neutron stars.They should be small in size due to the fact that after the exhaustion of the stellar "fuel" they also began to shrink, but due to of its mass, this contraction did not stop when the star "momentarily" became a white dwarf.
It continued until the matter of the star became so dense that it almost equaled the density of atomic nuclei. This is the reason why neutron stars have such small masses. By the way, because of the variability of radio beacons on such stars, they were called pulsars. Several hundred have now been found. Our Sun will never become a pulsar due to the smallness of its mass. Now, if it were two times more massive, then another thing! A very small star, but very hot, would show off in our sky.
The fate of very obese stars
And if the star is even more massive, well, for example, more than 3 times more massive than the Sun, what then? Just as it is difficult for an obese person to keep himself on his feet, so a “fat” star can only be in balance up to a certain time. When the internal thermonuclear heat of such stars ends, they, like white dwarfs, or like neutron stars, begin to shrink. In this case, the compression will already be catastrophic - the star tends to take up as little space as possible in space!
And at some stage of compression, the star, as it were, disappears for an external observer. This is how black holes appear! If it were possible to compress the Sun to a size of 6 km, then it would become a black hole.
How to see the invisible?
The hero of the famous novel by H. G. Wells "The Invisible Man", to live among people, wrapped himself in gauze. True, then instead of a face you could see something strange, but at least tangible! So are black holes - in order to "see" them ”, they, too, must be wrapped in something.
Single black holes are very difficult to detect, although interstellar dust particles and gas atoms fall into them. But they release little energy, so their SOS calls are too weak. True, supermassive black holes are discovered in this way, but such objects are not "relatives" of stars. In the cores of galaxies, such objects can contain so much substance inside that one could "blind" hundreds of millions and billions of ordinary stars.
And where can so much matter fall onto a black hole that was once a star that it will be able to “light up” itself? Of course, if there is another star nearby. A space monster literally rips off part of its substance from an ordinary star, which falls at a black hole with increasing speed, heating up to temperatures of millions of degrees! This is the gas that glows! Thus, several black holes have been discovered in our Galaxy. How many can there be? The answer to this question depends on what is the fate of stellar outcasts. Now almost no one knows what will happen to black holes in the future. After all, in principle, all matter in the Universe should turn into white dwarfs, neutron stars and black holes. But we see the whole sky in the stars. So , with stellar "corpses" something happens that allows them to turn into ordinary matter, from which new generations of stars arise. But what exactly?
There was a star and it is not
If you take a dozen stars and follow them, then surely one of them will turn into a black hole. Why, as a result of truly titanic work over the decades, only a few black holes have been discovered in our Galaxy? Maybe the picture of the disappearance of a star occurs imperceptibly to the outside world? The fact of the matter is that before moving to another world, a star experiences a grandiose catastrophe in its life - it explodes, sometimes throwing off most of its substance. But from the remaining substance of the star, as it were, it leaves behind a tombstone in the form of a black hole. But we know that stellar outbursts are rare. And if we knew which of them in the sky would let us know about their death with a grandiose firework, then we could observe the birth of an empty place both in space and in time. Why a hole in space is already clear, but why is it in time?
Let's remember that in moving systems time flows differently than on Earth - it slows down. The closer the star's contraction rate is to the speed of light, the slower time flows there. It seems to freeze if the star crosses the gravitational radius. Time on a black hole stops flowing - why not a hole in time! It turns out that we should not notice the transition of a star into oblivion?
The light from the star will weaken due to the fact that the substance of the black hole seems to be moving away from us at an ever greater speed. This is what will cause the shrinking star to disappear from this world long before it becomes a real black hole.
If we had equipment capable of monitoring millions of stars at the same time, then the detection of stars that said goodbye to their brethren by stopping sending them light would have been done a long time ago. It is quite possible that just one of these days we will learn about the discovery of such a phenomenon. American scientists have put into operation a system with which they monitor the state of the starry sky. The purpose of this system is very practical - the early detection of objects that may collide with the Earth. But it is also suitable for discovering black holes!
"Black holes don't have hair"
This is how J. Wheeler characterized the properties of black holes, meaning that it would be very difficult to distinguish two black holes from each other. Of the various properties of stellar objects, only mass, electric charge and rotation will remain. Imagine gatherings of black holes: they would be very bored - they would all have the same "face". Imagine that two very different objects, say, Quasimodo and Narcissus, fall into a black hole. After a while, distinguish them from each other already will be impossible.
Black holes can also differ in that one hole can rotate faster than another, and in 1 second they can make hundreds of thousands of revolutions around their axis.
In addition, they can also be charged differently. The last property defines a very exotic property of black holes: they can glow! But this space lantern will be very weak.
Roller coaster near black holes
Thrill-seekers will be able to test their nerves in the distant future by traveling around black holes. Sometimes science fiction novels describe a terrible situation when a spacecraft is captured by a black hole: once in the monster's gravitational field, the spaceship falls uncontrollably into the "hell". Chaos and confusion then reign among the stargazers - they will inevitably be torn apart by gravity drops in the monstrous gravitational field of the black hole. But such a description is only partially true! A starship approaching from afar to an orbit having a radius twice that of gravity will wrap itself around a black hole, and then fly away into space again, of course, if the crew does not have a thirst to fall into the arms of a black hole themselves! will be captured if it comes close to an orbit measuring two gravitational radii.
The described picture is possible due to the fact that the movement of celestial bodies around a black hole occurs in an amazing way. It is known from Newtonian mechanics that any body can move around another, more massive one along a very limited number of curves - an ellipse, a parabola or a hyperbola. If the ellipse is a closed curve, then the other two are open. The planets move around the Sun in elliptical orbits - this is Kepler's famous first law, established back in 1609. Of course, no body in the solar system can leave the limits of gravity of the sun. And any body flying past the Sun, for example, a comet, cannot be captured by it. This object needs to get rid of excess energy in order to move from a hyperbolic orbit to an elliptical one. And this means that the presence of a third body is necessary for capture. And around a black hole, a circular movement cannot be carried out for a long time, since any movement there is unstable. A small perturbation can “knock” a body out of orbit, so it will either fall into a black hole or leave it.
Future superweapon?
The Englishman R. Penrose proposed a way to extract energy from black holes. True, in this case, the black hole must be rotating, but what in the Universe does not rotate. If the spacecraft falls into the sphere of influence of a black hole, the so-called ergosphere, in which the vortex gravitational field is located, then by turning on the engine there, the ship will fly out of it, having more energy than it had before. The ship seems to capture some of the energy of the "monster", thereby reducing its mass. Unique objects, which were called gravitational bombs, can be created on this property. To create such a unique one, it is necessary to surround the black hole with an artificial sphere and send radiation there. It can be enhanced a black hole and go away, but this is prevented by the mirror surface of the sphere.The beam of light will again return to the black hole, after interacting with which it will again increase its energy, and so on until the amount of energy is so large that it breaks the sphere. for a fantastic thriller about the struggle between two civilizations! It is impossible to make such a bomb now, since we still do not know how to create black holes and are unlikely to be able to do it in the near future. We will not be able to fly to the nearest black hole soon either.
Time travel?
Black holes are associated with travel through time and space. According to ID Novikov, the collapsing matter, before reaching zero volume, can begin to expand, and the object can again appear in the field of view of an external observer, but in another Universe. And I. S. Shklovsky believed that after passing through the gravitational radius, the observer would see the entire future of the Universe in a short time! "Jumping out" into the "new" Universe, the traveler will see the entire past history of the new Universe. True, recent studies show that if such transitions are possible, then only in rare cases.
What only there are no black holes!
Is there a limit to the mass of a black hole, that is, can there be cosmic "monsters" with masses, for example, thousands of times greater than the sun. There are no restrictions on the mass of black holes, except for restrictions on the minimum mass. Astronomers believe that they are long- black holes have long been “discovered”: supermassive black holes can be sources of activity for some galaxies. There are practically no other explanations why quasars radiate such a huge amount of energy from a small volume, as its release when the surrounding matter, even whole stars, falls onto a supermassive black hole. Even at the center of our own Galaxy, scientists suspect the presence of a huge black hole.
Supermassive black holes have already been discovered by the dozens and everywhere. Near the central part of the M15 globular cluster of our galaxy, stars move at unusually high speeds. This speaks of the enormous mass of that compact object, around which the stars are forced to rush at speeds that terrify the imagination so as not to fall into a black hole.
And the activity of many galaxies cannot be explained without assuming the presence of very massive black holes in their central regions. The masses of some of them are measured in billions of solar masses.
Is there a black hole nearby?
It is interesting to know about black holes, but being near these "monsters of the Universe", as K. Thorn, their famous researcher, called them, is not always safe. Is there a similar object near the Solar System? This would not be unusual, since black There are many holes in our galaxy, but there is no evidence of their close presence, because before the appearance of a black hole, a supernova must occur. million years ago, the dinosaurs died out due to the fact that not far from the Sun, some kind of star flared up. Deadly radiation destroyed much of what existed on Earth at that time. But where is the black hole that was supposed to remain from it? Not rushing is she on us now?
Let's end our story about black holes with an episode from the same book about Alice, who asks the Cat to "disappear and appear not so suddenly," because she otherwise feels dizzy. And then the Cat disappeared, but very slowly, and the smile disappeared last. hovered in the air when everything else was already gone.
D-yes! thought Alice. - I saw cats without smiles, but a smile without a cat! I have never seen anything like this in my life."
The concept of a black hole was treated with caution just a decade ago, believing that this is nothing more than one of the theories put forward by astrophysicists. Since then, much has changed, and now the existence of black holes is no longer disputed by anyone.
What is a black hole
When a star dies, amazing transformations happen to it. Due to the lack of hydrogen, which gradually burns out, the aging star grows in size, which subsequently leads to its explosion. After this happens, the cooled star is subjected to a powerful effect of gravity and becomes a small body, by the standards of space, but with a powerful gravitational field that draws in everything that is in the access zone.
These very "gluttonous" space objects are capable of absorbing with undisguised appetite both spaceships, and rays of light, and stardust, and not very large stars, such as ours, if they are nearby.
A curious fact is that a black hole is practically invisible - earthly astronomers do not yet have instruments and other tools to see it. Scientists judge the presence of a black hole only by external manifestations, watching how this space vacuum cleaner greedily sucks in another star. At the same time, the black hole behaves like a bloodthirsty predator: by tightening the victim, it makes it shatter to pieces. And in the last stage, the disappearing object begins to emit a parting light before becoming invisible. Moreover, these parting rays are X-rays, which made it possible for scientists to see the amazing process.
How many black holes are there in the universe
Astrophysicists claim that this phenomenon is widespread in the Universe. Such eaters of stars and matter are present in every Galaxy. Therefore, if there are other civilizations than the earth, then no one can feel safe, and therefore it is not superfluous to think in advance about the development of not only other planets, but also other star systems.
Cluster of black holes
The fact is that it is necessary to vigilantly track not only the black holes already known to astronomers today, but also to observe the processes as a result of which the same black holes can appear much closer to the Earth. While the closest of them, according to scientists, is present in our Galaxy, it was called Sagittarius. And we have to console ourselves with the fact that this most merciless Sagittarius is far from our planet, although it belongs to the rank of supermassive.
The Earth and the Sun until the black hole threatens
Our planetary system can still feel relatively safe from black holes, unless, of course, it blows itself up as a result of conflicts. A hint, of course, at the conflicts that have flared up on Earth. As for Sagittarius, he is waiting for his new victims at a distance of more than 20 thousand light years from us. Therefore, its activities can still be observed with the inquisitiveness of scientists investigating the activity of a spider that weaves its webs, but does not threaten us in any way. So far, nothing suggests that a black hole may appear in our Galaxy in the coming centuries.
