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

What are black holes?

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

Nowadays, a black hole is a region of time and space that has such gravity that even a ray of light cannot escape from it.

How are black holes formed?

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

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

At the center of all galaxies is a supermassive black hole. According to Einstein's theory of relativity:

“Any mass distorts space and time.”

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

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

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

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

Black holes and galaxies

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

Types of black holes

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

At the moment, there are a large number of open questions that have yet to be answered by future generations. For example, can so-called “wormholes” really exist, with the help of which one can travel through space and time. What exactly happens inside a black hole and what laws these phenomena obey. And what about the disappearance of information in a black hole?

Every person who gets acquainted with astronomy sooner or later experiences a strong curiosity about the most mysterious objects of the Universe - black holes. These are real lords of darkness, capable of “swallowing” any atom passing nearby and not allowing even light to escape - their attraction is so powerful. These objects pose a real challenge for physicists and astronomers. The former cannot yet understand what happens to the matter that has fallen inside the black hole, and the latter, although they explain the most energy-consuming phenomena in space by the existence of black holes, have never had the opportunity to observe any of them directly. We will tell you about these interesting celestial objects, find out what has already been discovered and what remains to be learned in order to lift the veil of secrecy.

What is a black hole?

The name “black hole” (in English - black hole) was proposed in 1967 by the American theoretical physicist John Archibald Wheeler (see photo on the left). It served to designate a celestial body, the attraction of which is so strong that even light does not let go of itself. That is why it is “black” because it does not emit light.

Indirect observations

This is the reason for such mystery: since black holes do not glow, we cannot see them directly and are forced to look for and study them using only indirect evidence that their existence leaves in the surrounding space. In other words, if a black hole engulfs a star, we cannot see the black hole, but we can observe the devastating effects of its powerful gravitational field.

Laplace's intuition

Although the expression “black hole” to denote the hypothetical final stage of the evolution of a star that has collapsed into itself under the influence of gravity is relatively recent, the idea of ​​the possibility of the existence of such bodies arose more than two centuries ago. The Englishman John Michell and the Frenchman Pierre-Simon de Laplace independently hypothesized the existence of “invisible stars”; at the same time, they were based on the usual laws of dynamics and Newton’s law of universal gravitation. Today, black holes have received their correct description based on Einstein's general theory of relativity.

In his work “Exposition of the System of the World” (1796), Laplace wrote: “A bright star of the same density as the Earth, with a diameter 250 times greater than the diameter of the Sun, would, thanks to its gravitational attraction, prevent light rays from reaching us. Therefore, it is possible that the largest and brightest celestial bodies are invisible for this reason.”

Invincible gravity

Laplace's idea was based on the concept of escape velocity (second cosmic velocity). A black hole is such a dense object that its gravity can hold back even light, which develops the highest speed in nature (almost 300,000 km/s). In practice, escaping from a black hole requires speeds greater than the speed of light, but this is impossible!

This means that a star of this kind will be invisible, since even light will not be able to overcome its powerful gravity. Einstein explained this fact through the phenomenon of light bending under the influence of a gravitational field. In reality, near a black hole, space-time is so curved that the trajectories of light rays also close on themselves. In order to turn the Sun into a black hole, we will have to concentrate all of its mass in a ball with a radius of 3 km, and the Earth will have to turn into a ball with a radius of 9 mm!

Types of black holes

Just about ten years ago, observations suggested the existence of two types of black holes: stellar, whose mass is comparable to the mass of the Sun or slightly exceeds it, and supermassive, whose mass ranges from several hundred thousand to many millions of solar masses. However, relatively recently, X-ray images and high-resolution spectra obtained from artificial satellites such as Chandra and XMM-Newton brought to the fore a third type of black hole - with an average mass exceeding the mass of the Sun by thousands of times.

Stellar black holes

Stellar black holes became known earlier than others. They are formed when a large-mass star, at the end of its evolutionary path, exhausts its reserves of nuclear fuel and collapses into itself due to its own gravity. An explosion that shakes a star (a phenomenon known as a “supernova explosion”) has catastrophic consequences: if the star’s core is more than 10 times the mass of the Sun, no nuclear force can resist the gravitational collapse that will result in the creation of a black hole.

Supermassive black holes

Supermassive black holes, first noted in the nuclei of some active galaxies, have a different origin. There are several hypotheses regarding their birth: a stellar black hole, which over the course of millions of years devours all the stars around it; a cluster of black holes merging together; a colossal gas cloud collapsing directly into a black hole. These black holes are among the most energetic objects in space. They are located at the centers of many, if not all, galaxies. Our Galaxy also has such a black hole. Sometimes, due to the presence of such a black hole, the cores of these galaxies become very bright. Galaxies with black holes at the center, surrounded by large amounts of falling matter and therefore capable of producing colossal amounts of energy, are called "active" and their cores are called "active galactic nuclei" (AGN). For example, quasars (the most distant cosmic objects from us that are accessible to our observation) are active galaxies in which we see only a very bright core.

Medium and mini

Another mystery remains the medium-mass black holes, which, according to recent research, may be at the center of some globular clusters, such as M13 and NCC 6388. Many astronomers are skeptical about these objects, but some new research suggests the presence of black holes medium-sized even near the center of our Galaxy. English physicist Stephen Hawking also put forward a theoretical assumption about the existence of a fourth type of black hole - a “mini-hole” with a mass of only a billion tons (which is approximately equal to the mass of a large mountain). We are talking about primary objects, that is, those that appeared in the first moments of the life of the Universe, when the pressure was still very high. However, not a single trace of their existence has yet been discovered.

How to find a black hole

Just a few years ago, a light came on over black holes. Thanks to constantly improving instruments and technologies (both ground-based and space-based), these objects are becoming less and less mysterious; more precisely, the space surrounding them becomes less mysterious. In fact, since the black hole itself is invisible, we can only recognize it if it is surrounded by enough matter (stars and hot gas) orbiting around it at a short distance.

Watching binary systems

Some stellar black holes have been discovered by observing the orbital motion of a star around an unseen companion in a binary system. Close binary systems (that is, consisting of two stars very close to each other), in which one of the companions is invisible, are a favorite object of observation for astrophysicists searching for black holes.

An indication of the presence of a black hole (or neutron star) is the strong emission of X-rays caused by a complex mechanism that can be schematically described as follows. Thanks to its powerful gravity, a black hole can rip matter out of its companion star; this gas spreads out into a flat disk and spirals down into the black hole. Friction resulting from collisions between particles of falling gas heats the inner layers of the disk to several million degrees, which causes powerful X-ray radiation.

X-ray observations

X-ray observations of objects in our Galaxy and neighboring galaxies, carried out for several decades, have made it possible to detect compact binary sources, about a dozen of which are systems containing black hole candidates. The main problem is determining the mass of an invisible celestial body. The mass (although not very precise) can be found by studying the motion of the companion or, much more difficult, by measuring the intensity of the X-ray radiation of the falling material. This intensity is related by an equation to the mass of the body on which this substance falls.

Nobel laureate

Something similar can be said for supermassive black holes observed in the cores of many galaxies, the masses of which are estimated by measuring the orbital velocities of the gas falling into the black hole. In this case, caused by the powerful gravitational field of a very large object, a rapid increase in the speed of gas clouds orbiting in the center of galaxies is detected by observations in the radio range, as well as in optical rays. Observations in the X-ray range can confirm the increased release of energy caused by matter falling into the black hole. Research in X-rays was started in the early 1960s by the Italian Riccardo Giacconi, who worked in the USA. His Nobel Prize in 2002 recognized his "pioneering contributions to astrophysics leading to the discovery of X-ray sources in space."

Cygnus X-1: first candidate

Our Galaxy is not immune to the presence of candidate black hole objects. Fortunately, none of these objects are close enough to us to pose a threat to the existence of Earth or the solar system. Despite the large number of compact X-ray sources that have been identified (and these are the most likely candidates for black holes), we have no confidence that they actually contain black holes. The only one among these sources that does not have an alternative version is the close binary system Cygnus X-1, that is, the brightest source of X-ray radiation in the constellation Cygnus.

Massive stars

This system, whose orbital period is 5.6 days, consists of a very bright blue star of large size (its diameter is 20 times that of the Sun, and its mass is about 30 times larger), easily visible even in your telescope, and an invisible second star, the mass of which is estimated at several solar masses (up to 10). Located 6,500 light-years away, the second star would be perfectly visible if it were an ordinary star. Its invisibility, the powerful X-ray emission produced by the system and, finally, the mass estimate lead most astronomers to believe that this is the first confirmed discovery of a stellar black hole.

Doubts

However, there are also skeptics. Among them is one of the largest researchers of black holes, physicist Stephen Hawking. He even made a bet with his American colleague Keel Thorne, an ardent supporter of classifying the Cygnus X-1 object as a black hole.

The debate over the identity of the Cygnus X-1 object is not Hawking's only bet. Having devoted several nine years to theoretical studies of black holes, he became convinced of the fallacy of his previous ideas about these mysterious objects. In particular, Hawking assumed that matter, after falling into a black hole, disappears forever, and with it all of its information luggage disappears. He was so sure of this that he made a bet on this topic in 1997 with his American colleague John Preskill.

Admitting a mistake

On July 21, 2004, in his speech at the Congress on the Theory of Relativity in Dublin, Hawking admitted that Preskill was right. Black holes do not lead to the complete disappearance of matter. Moreover, they have a certain kind of “memory”. They may well contain traces of what they have consumed. Thus, by “evaporating” (that is, slowly emitting radiation due to the quantum effect), they can return this information to our Universe.

Black holes in the Galaxy

Astronomers still have many doubts about the presence of stellar black holes (like the one belonging to the binary system Cygnus X-1) in our Galaxy; but there is much less doubt about supermassive black holes.

In the center

Our Galaxy has at least one supermassive black hole. Its source, known as Sagittarius A*, is precisely localized in the center of the plane of the Milky Way. Its name is explained by the fact that it is the most powerful radio source in the constellation Sagittarius. It is in this direction that both the geometric and physical centers of our galactic system are located. Located about 26,000 light-years away, the supermassive black hole associated with radio wave source Sagittarius A* has a mass estimated at about 4 million solar masses, contained in a space the volume of which is comparable to the volume of the solar system. Its relative proximity to us (it is by far the closest supermassive black hole to Earth) has led to the object being studied particularly closely in recent years by the Chandra space observatory. It turned out, in particular, that it is also a powerful source of X-ray radiation (but not as powerful as sources in active galactic nuclei). Sagittarius A* may be a dormant remnant of what was the active core of our Galaxy millions or billions of years ago.

Black hole

Black holes are limited areas of outer space in which the force of gravity is so strong that even photons of light radiation cannot leave them, being unable to escape from the merciless embrace of gravity.

How are black holes formed?

Scientists believe that there may be several types of black holes. One type can form when a massive old star dies. In the Universe, stars are born and die every day.

Another type of black hole is believed to be the huge dark mass at the center of galaxies. Colossal black objects form from millions of stars. Finally, there are mini black holes, about the size of a pinhead or a small marble. Such black holes form when relatively small amounts of mass are squished to unimaginably small sizes.

The first type of black hole is formed when a star, 8 to 100 times larger than our Sun, ends its life with a grand explosion. What remains of such a star contracts, or, scientifically speaking, creates a collapse. Under the influence of gravity, the compression of the star's particles becomes tighter and tighter. Astronomers believe that at the center of our Galaxy - the Milky Way - there is a huge black hole whose mass exceeds the mass of a million suns.

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Interesting facts about stars

Why is a black hole black?

Gravity is simply the attraction of one piece of matter towards another. Thus, the more matter gathered in one place, the greater the force of attraction. On the surface of a super-dense star, due to the fact that the huge mass is concentrated in one limited volume, the force of attraction is unimaginably strong.

As the star shrinks further, the force of gravity increases so much that light cannot even be emitted from its surface. Matter and light are irretrievably absorbed by the star, which is therefore called a black hole. Scientists do not yet have clear evidence of the existence of such megamassive black holes. They again and again point their telescopes at the centers of galaxies, including the center of our Galaxy, to explore these strange areas and finally obtain evidence of the existence of black holes of the second type.

A black hole is a special region in space. This is a certain accumulation of black matter, capable of drawing into itself and absorbing other objects in space. The phenomenon of black holes is still not. All available data are just theories and assumptions of scientists astronomers.

The name "black hole" was coined by the scientist J.A. Wheeler in 1968 at Princeton University.

There is a theory that black holes are stars, but unusual ones, like neutron ones. A black hole - - because it has a very high luminescence density and sends out absolutely no radiation. Therefore, it is invisible neither in infrared, nor in x-rays, nor in radio rays.

The French astronomer P. Laplace discovered this situation 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 light rays to spread throughout the Universe due to its gravity, and therefore remains invisible. Thus, it is assumed that black holes are the most powerful emitting objects in the Universe, but they do not have a solid surface.

Properties of black holes

All supposed properties of black holes are based on the theory of relativity, derived in the 20th century by A. Einstein. Any traditional approach to studying 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 caught in its gravitational field will inevitably be pulled in, 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 transformed. Scientists, by calculation, are still inclined to conclude that black holes are not celestial bodies in the generally accepted 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 astronomers' calculations, 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 greater than 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 scientists’ research is still too far from understanding what processes and capabilities black holes hide. It is quite possible that something similar could happen in the future.

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 single it out as a separate star or planet, since it is neither a solid nor a gaseous 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 greater the gravitational force. This is inextricably linked to the Big Bang Theory, 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. Actually this is not 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 that 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 go 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, getting there, do not simply disappear. Their mass is multiplied by the mass of the singularity, which makes it even larger and enlarges it. Thus, if inside the wormhole you turn on a flashlight to look around, it will not glow. The emitted quanta will constantly multiply by the mass of the hole, and you, roughly speaking, will only make your situation worse.

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 the 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 is close to a vacuum. But they completely lose their significance on the event horizon. This is why, from a mathematical point of view, it is impossible to calculate 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, some more are added to the existing dimensions. 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.