Black holes - an explanation for children. Methodical manual "Black holes in space and on Earth"

30.09.2019 -

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, the phenomenon of “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 break away, 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 - by-product 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.

Currently exists 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?

All-Russian youth competition research work them. V. I. Vernadsky 2013-14

1. Introduction
My name is Sasha Voynov. I am 8 years old. I'm in second grade. I really like watching the stars. I love studying everything related to space. There are many mysterious and insufficiently studied objects in the Universe. One of the most interesting objects is black holes. Many people believe that black holes do not exist. I will try to prove that they exist.
The topic of black holes is one of the most pressing topics in modern astronomy, astrophysics and cosmology, since these objects help to better understand the structure of our universe, from the moment of the big bang to the present day, and will also allow us to understand what will happen to our universe in the future.
Purpose of the study: to formulate the concept of “black hole of space”.

Tasks:
1. Study the history of the issue of black holes.
2. Systematize and study information about black holes (occurrence, properties).
3. Conduct experiments.
Research methods: work with literary sources and Internet resources, experiment.
Novelty of the research: the term “Black hole” appeared a long time ago, but a complete study of black holes has not yet been carried out. I came up with experiments with the goal of explaining some of the properties of black holes.
Literature review:
Source of information What I learned
Hawking S. Three books about space and time. The history of the idea of “Black Holes”; how black holes appear, the concept of star collapse; what does space distortion mean? where do black holes live
KIP S. Thorne. Black holes and folds of time: Einstein's daring legacy. How space and time distortion occurs; Einstein's contribution to the development of the theory of the existence of black holes
Ian Nicholson. Universe. Series “Life of the Planet” What does supermassive stars mean, comparison of the sizes of the sun, stars with the size of a car
I explore the world: Det. encycl.: Physics General information about the black hole: the story of how they appear
I explore the world: Det. encycl.: Space The history of the term “Black hole”
encyclopedic Dictionary young physicist. What does it mean: gravity, mass, attraction, particle; Newton's work - light consists of particles
Encyclopedic Dictionary of a Young Astronomer. Theories of black holes
News about space and UFOs Pictures and photos depicting black holes
WWalls.RU: desktop wallpaper. Space Pictures and photos of black holes

2.History of the idea
The term “BLACK HOLE” appeared quite recently, in the twentieth century. It was invented by the American scientist John Wheeler.
However, attempts to explain this mysterious phenomenon were made a long time ago, about 200 years ago.
Isaac Newton believed that light consists of particles. This means that it has mass and is affected by gravity.
Based on this, the English astronomer John Michell suggested that such massive stars may exist in nature that even a ray of light is not able to leave their surface.
The great scientist Albert Einstein theoretically proved the possibility of the existence of black holes.
In 1934, American physicists put forward a hypothesis about the dying of a star. And already in 1939 they proved that: “A black hole absorbs everything and releases nothing!”

3.Theories of the emergence of black holes:
How do black holes form (emerge)? There are three theories of the origin of black holes:
1. Collapse of a star under the influence own strength gravity: large stars exist due to their own energy. The star lives until this energy runs out. As the size of a star decreases, its density increases, which leads to an increase in the mass of the star. If the mass of the star is more than three solar, this leads to the collapse of the star.
2. 14 billion years ago the expansion of our Universe began. There is a theory that high densities were observed everywhere at that time. Therefore, small changes in density in that era could lead to the birth of black holes of any mass, including small ones.
3. There is an assumption that black holes can arise from the collision of fast elementary particles. When two particles collide violently, they can be compressed strongly enough to create a microscopic black hole. After this, it will collapse almost instantly.

4.Properties of black holes
1) Time flows slower near a black hole than far from it. If an observer who is at some distance from the black hole throws a luminous object, such as a flashlight, towards the black hole, he will see it fall faster and faster, but then begin to slow down, and its light will dim and turn red. From the point of view of a distant observer, the lantern will practically stop and become invisible, never being able to cross the surface of the black hole. But if the observer himself jumped there with a lantern, he would fall to the center of the black hole in a short time, being torn apart by its powerful tidal gravitational forces arising from the difference in gravity at different distances from the center. That is, if something (someone) penetrates the event horizon, it will never return.
2) If the body from which the black hole arose was rotating, then a “vortex” gravitational field (funnel) is maintained around the black hole, dragging all neighboring bodies into rotational motion around it.
3) When a body is compressed into a black hole, then all its characteristics, except mass, electric charge and angular momentum, disappear (such as composition, density, volume, etc.).
4) The boundary of a black hole is called the event horizon. The matter that falls into the event horizon of a black hole will certainly form a singularity (a region of infinitely small sizes) with an immeasurably huge density, due to which all the matter of the star is destroyed.
5) A black hole can “evaporate” very slowly. Stephen Hawking discovered this. They proved that black holes are capable of releasing matter and radiation, but this can only be noticed if the mass of the black hole itself is low enough.
6) A black hole has a huge, inexhaustible supply of energy.

5.Where are black holes located?
The very first question that worries people about the problem of black holes is the desire to find out where black holes are located. In reality, black holes are scattered throughout the Universe. A black hole can form anywhere, including near the solar system.

6.Description of experiments
First experience “Invisible reality”
Imagine that our Earth is the Universe, and everything that is on it (people, animals, plants) are objects of the Universe (i.e. stars, planets, comets). If we close our eyes, we will not see anything, but this does not mean that everything around us has disappeared.
Second experiment “Space distortion”
Take a piece of paper and put two dots. Let's connect the points with a straight line. Determine the distance between points using a ruler. Now let's crumple the sheet. The distance between points has decreased. Thus, we can talk about changes in space inside the black hole.
Third experiment “The color of a black hole”
Let's take two boxes with small round holes. We will paint one inside white and the other black. Let's look through the holes in the boxes. There is nothing visible in both boxes. Let's place objects - they are also not visible. Therefore, we can say that black holes are not necessarily black inside. It follows that black holes are not necessarily black.
8. Conclusions
So, in my opinion, as part of my work, I was able to form an understanding of what a black hole is: I studied the literature, systematized the information received, got acquainted with the history this issue, examined the properties of black holes and conducted experiments.
Black holes are absolutely amazing objects, unlike anything known so far. These are holes in space and time that arise due to a very strong curvature of space and a change in the nature of the flow of time in a rapidly growing gravitational field. In the future, I want to continue my work on studying these interesting objects, since black holes have enormous energy that can be used for the needs of humanity.

Bibliography
1. Hawking S. Three books about space and time. Translation from English – St. Petersburg: Amphora. TID Amphora, 2012. p. 106-109, 123-127, 330-340.
2. KIP S. Thorne. Black holes and folds of time: Einstein's daring legacy. Translation from English Ed. Corresponding member Ran V.B. Braginsky. – M.: Publishing house of physical and mathematical literature, 2009., p. 23, 122-124.
3. Ian Nicholson. Universe. Series “Life of the Planet” - M.: “Rosman”, 2000. p. 21-22.
4. I explore the world: Det. encycl.: Physics / Comp., art. A.A. Leonovich; Under general ed. O. G. Hinn. – M.: OOO Firma Publishing House AST, 1999.
5. I explore the world: Det. encycl.: Space/Aut. - comp. T.I. Gontaruk - M.: LLC Publishing House AST, 1999. p. 355-358.
6. Encyclopedic Dictionary of a Young Physicist. Pedagogy, 1984. p. 286.
7. Encyclopedic Dictionary of a Young Astronomer. Pedagogy, 1986. p. 298-301.
8. News about space and UFOs // Personal website // (access date: 10.15.13)
9. WWalls.RU: wallpaper for your desktop. Space // Personal website // (access date: 10/15/13)

Issue 39

In a new astronomy video lesson, the professor will talk about how black holes are formed and why they are dangerous.

How black holes form

Black holes cannot be touched and you cannot walk through them. Black holes are regions in space-time that form a super-powerful attraction. Attraction bends space and time, which means that inside black hole there are no straight lines, the space is crumpled and intertwined. If a star forms near a black hole, the gravitational forces of the black hole will tear the star apart and it will disappear into the depths of the hole. If something falls into a black hole, it stays there forever. To overcome the powerful attraction of a black hole, it is necessary to develop a speed greater than the speed of light, but this, alas, is impossible. Scientists do not know exactly how supermassive black holes are formed, but with ordinary black holes everything is more or less clear. During the evolution of a star, hydrogen gradually burns out, and accordingly its amount decreases, which leads to the fact that the force of light pressure begins to exceed the force of gravitational compression. The star greatly increases in size and turns into a red giant, which subsequently explodes. After the explosion, compression begins, then the star cools down and becomes not directly visible. But, if the mass of the red giant remnant exceeds the solar mass by 2-2.5 times, then its compression cannot stop, since the gravitational force completely suppresses the resistance to compression, as a result, this remnant is compressed into a dense tiny body, as if closing in on itself. And it is at this moment of gravitational collapse (compression) that black holes are formed. As a result, it turns out that the mass is concentrated in such a small area that even the speed of light is not enough to leave its vicinity. Hence the first part of the name is black, since it can even absorb light. The second part - the hole - means that everything that falls into the region of the black hole becomes forever inaccessible to observation.

You've probably seen science fiction films where heroes, traveling in space, find themselves in another universe? Most often, mysterious cosmic black holes become the door to another world. It turns out there is some truth to these stories. Scientists say so.

When the very center of a star - in its core - runs out of fuel, all its particles become very heavy. And then, the entire planet collapses into its center. This causes a powerful shock wave that ruptures the outer, still burning, shell of the star and it explodes in a blinding flash. One teaspoon of a small extinct star weighs several billion tons. Such a star is called neutron. And if a star is twenty to thirty times larger than our sun, its destruction leads to the formation of the strangest phenomenon in the universe - black hole.

The gravity in a Black Hole is so strong that it traps planets, gases and even light. Black holes are invisible, they can only be found by a huge funnel of cosmic bodies flying into it. Only around some holes does a bright glow form. After all, the rotation speed is very high, particles of celestial bodies heat up to millions of degrees and glow brightly

Cosmic black hole attracts all objects, twisting them in a spiral. As objects approach a black hole, they begin to accelerate and stretch out, like giant spaghetti. The force of attraction gradually increases and at some point becomes so monstrous that nothing can overcome it. This boundary is called the event horizon. Any event that happens behind it will remain invisible forever.

Scientists suggest that black holes can create tunnels in space - “wormholes”. If you fall into it, you can pass through space and find yourself in another Universe, where the opposite white hole exists. Maybe someday this secret will be revealed and people will travel to other dimensions on powerful spaceships.

The concept of a black hole is known to everyone - from schoolchildren to the elderly; it is used in science and fiction literature, in the yellow media and at scientific conferences. But what exactly such holes are is not known to everyone.

From the history of black holes

1783 The first hypothesis of the existence of such a phenomenon as a black hole was put forward in 1783 by the English scientist John Michell. In his theory, he combined two of Newton's creations - optics and mechanics. Michell's idea was this: if light is a stream of tiny particles, then, like all other bodies, the particles should experience the attraction of a gravitational field. It turns out that the more massive the star, the more difficult it is for light to resist its attraction. 13 years after Michell, the French astronomer and mathematician Laplace put forward (most likely independently of his British colleague) a similar theory.

1915 However, all their works remained unclaimed until the beginning of the 20th century. In 1915, Albert Einstein published the General Theory of Relativity and showed that gravity is the curvature of spacetime caused by matter, and a few months later, German astronomer and theoretical physicist Karl Schwarzschild used it to solve a specific astronomical problem. He explored the structure of curved space-time around the Sun and rediscovered the phenomenon of black holes.

(John Wheeler coined the term "Black holes")

1967 American physicist John Wheeler outlined a space that can be crumpled, like a piece of paper, into an infinitesimal point and designated it with the term “Black Hole”.

1974 British physicist Stephen Hawking proved that black holes, although they absorb matter without return, can emit radiation and eventually evaporate. This phenomenon is called “Hawking radiation”.

Nowadays. The latest research into pulsars and quasars, as well as the discovery of cosmic microwave background radiation, has finally made it possible to describe the very concept of black holes. In 2013, the G2 gas cloud came very close to the Black Hole and will most likely be swallowed up by it; observations of the unique process will provide enormous opportunities for new discoveries of the features of black holes.

What black holes actually are

A laconic explanation of the phenomenon goes like this. A black hole is a space-time region whose gravitational attraction is so strong that no object, including light quanta, can leave it.

The black hole was once a massive star. While thermonuclear reactions are maintained in its depths high pressure, everything remains normal. But over time, the energy supply is depleted and the celestial body, under the influence of its own gravity, begins to shrink. The final stage of this process is the collapse of the stellar core and the formation of a black hole.

1. A black hole ejects a jet at high speed

2. A disk of matter grows into a black hole

3. Black hole

4. Detailed diagram of the black hole region

5. Size of new observations found

The most common theory is that similar phenomena exist in every galaxy, including the center of our Milky Way. The huge gravitational force of the hole is capable of holding several galaxies around it, preventing them from moving away from each other. The “coverage area” can be different, it all depends on the mass of the star that turned into a black hole, and can be thousands of light years.

Schwarzschild radius

The main property of a black hole is that any substance that falls into it can never return. The same applies to light. At their core, holes are bodies that completely absorb all light falling on them and do not emit any of their own. Such objects may visually appear as clots of absolute darkness.

1. Moving matter at half the speed of light

2. Photon ring

3. Inner photon ring

4. Event horizon in a black hole

Starting from General theory According to Einstein's relativity, if a body approaches a critical distance to the center of the hole, it will no longer be able to return. This distance is called the Schwarzschild radius. What exactly happens inside this radius is not known for certain, but there is the most common theory. It is believed that all the matter of a black hole is concentrated in an infinitesimal point, and at its center there is an object with infinite density, which scientists call a singular perturbation.

How does falling into a black hole happen?

(In the picture, the black hole Sagittarius A* looks like an extremely bright cluster of light)

Not so long ago, in 2011, scientists discovered a gas cloud, giving it the simple name G2, which emits unusual light. This glow may be due to friction in the gas and dust caused by the Sagittarius A* black hole, which orbits it as an accretion disk. Thus, we become observers of the amazing phenomenon of absorption of a gas cloud by a supermassive black hole.

According to recent studies, the closest approach to the black hole will occur in March 2014. We can recreate a picture of how this exciting spectacle will take place.

1. When first appearing in the data, a gas cloud resembles a huge ball of gas and dust.

2. Now, as of June 2013, the cloud is tens of billions of kilometers from the black hole. It falls into it at a speed of 2500 km/s.

3. The cloud is expected to pass by the black hole, but tidal forces caused by the difference in gravity acting on the leading and trailing edges of the cloud will cause it to take on an increasingly elongated shape.

4. After the cloud is torn apart, most of it will most likely flow into the accretion disk around Sagittarius A*, generating shock waves in it. The temperature will jump to several million degrees.

5. Part of the cloud will fall directly into the black hole. No one knows exactly what will happen to this substance next, but it is expected that as it falls it will emit powerful streams of X-rays and will never be seen again.

Video: black hole swallows a gas cloud

(Computer simulation of how much of the G2 gas cloud would be destroyed and consumed by the black hole Sagittarius A*)

What's inside a black hole?

There is a theory that states that a black hole is practically empty inside, and all its mass is concentrated in an incredibly small point located at its very center - the singularity.

According to another theory, which has existed for half a century, everything that falls into a black hole passes into another universe located in the black hole itself. Now this theory is not the main one.

And there is a third, most modern and tenacious theory, according to which everything that falls into a black hole dissolves in the vibrations of strings on its surface, which is designated as the event horizon.

So what is an event horizon? It is impossible to look inside a black hole even with a super-powerful telescope, since even light, entering the giant cosmic funnel, has no chance of emerging back. Everything that can be at least somehow considered is located in its immediate vicinity.

The event horizon is a conventional surface line from under which nothing (neither gas, nor dust, nor stars, nor light) can escape. And this is the very mysterious point of no return in the black holes of the Universe.