For modern scientists, a black hole is one of the most mysterious phenomena in our universe. The study of such objects is difficult, it is not possible to try them "by experience". The mass, density of the substance of a black hole, the processes of formation of this object, dimensions - all this arouses interest among specialists, and at times - bewilderment. Let's consider the topic in more detail. First, let's analyze what such an object is.
General information
An amazing feature of a space object is the combination of a small radius, a high density of black hole matter and an incredibly large mass. All currently known physical properties of such an object seem strange to scientists, often inexplicable. Even the most experienced astrophysicists are still amazed at the peculiarities of such phenomena. The main feature that allows scientists to identify a black hole is the event horizon, that is, the boundary due to whichnothing comes back, including the light. If a zone is permanently separated, the separation boundary is referred to as the event horizon. With temporary separation, the presence of a visible horizon is fixed. Sometimes temporal is a very loose concept, that is, the region may be separated for a period exceeding the current age of the universe. If there is a visible horizon that exists for a long time, it is difficult to distinguish it from the event horizon.
In many ways, the properties of a black hole, the density of the substance that forms it, are due to other physical qualities that operate in our world laws. The event horizon of a spherically symmetric black hole is a sphere whose diameter is determined by its mass. The more mass pulled inward, the larger the hole. And yet it remains surprisingly small against the background of stars, as gravitational pressure compresses everything inside. If we imagine a hole whose mass corresponds to our planet, then the radius of such an object will not exceed a few millimeters, that is, it will be ten billion less than the earth. The radius was named after Schwarzschild, the scientist who first deduced black holes as a solution to Einstein's general theory of relativity.
And inside?
Having got into such an object, a person is unlikely to notice a huge density on himself. The properties of a black hole are not well understood to be sure what will happen, but scientists believe that nothing special can be revealed when crossing the horizon. This is explained by the equivalent Einsteinianprinciple that explains why the field that forms the curvature of the horizon and the acceleration inherent in the plane do not differ for the observer. When tracking the crossing process from a distance, you can see that the object begins to slow down near the horizon, as if time passes slowly in this place. After some time, the object will cross the horizon, fall into the Schwarzschild radius.
The density of matter in a black hole, the mass of an object, its dimensions and tidal forces, and the gravitational field are closely related. The larger the radius, the lower the density. The radius increases with weight. The tidal forces are inversely proportional to the squared weight, that is, as the dimensions increase and the density decreases, the tidal forces of the object decrease. It will be possible to overcome the horizon before noticing this fact if the mass of the object is very large. In the early days of general relativity, it was believed that there was a singularity on the horizon, but this turned out not to be the case.
About Density
As studies have shown, the density of a black hole, depending on the mass, can be more or less. For different objects, this indicator varies, but always decreases with increasing radius. Supermassive holes may appear, which are formed in an extensive way due to the accumulation of material. On average, the density of such objects, whose mass corresponds to the total mass of several billion luminaries in our system, is less than the density of water. Sometimes it is comparable to the level of gas density. The tidal force of this object is activated already after the observer crosses the horizonevents. The hypothetical explorer would not be harmed as he approached the horizon, and would fall many thousands of kilometers if he found protection from the disk plasma. If the observer does not look back, he will not notice that the horizon has been crossed, and if he turns his head, he will probably see light rays frozen at the horizon. Time for the observer will flow very slowly, he will be able to track events near the hole until the moment of death - either her or the Universe.
To determine the density of a supermassive black hole, you need to know its mass. Find the value of this quantity and the Schwarzschild volume inherent in the space object. On average, such an indicator, according to astrophysicists, is extremely small. In an impressive percentage of cases, it is less than the level of air density. The phenomenon is explained as follows. The Schwarzschild radius is directly related to the weight, while the density is inversely related to the volume, and hence the Schwarzschild radius. The volume is directly related to the cubed radius. Mass increases linearly. Accordingly, the volume grows faster than the weight, and the average density becomes smaller, the larger the radius of the object under study.
Curious to know
The tidal force inherent in a hole is a gradient of the force of gravity, which is quite large on the horizon, so even photons cannot escape from here. At the same time, the increase in the parameter occurs quite smoothly, which makes it possible for the observer to overcome the horizon without risk to himself.
Studies of the density of a black hole inthe center of the object is still relatively limited. As established by astrophysicists, the closer the central singularity, the higher the density level. The calculation mechanism mentioned earlier allows you to get a very average idea of \u200b\u200bwhat is happening.
Scientists have extremely limited ideas about what is happening in the hole, its device. According to astrophysicists, the density distribution in a hole is not very significant for an outside observer, at least at the current level. Much more informative specification of gravity, weight. The larger the mass, the stronger the center, the horizon, are separated from each other. There are also such assumptions: just beyond the horizon, matter is absent in principle, it can only be detected in the depths of the object.
Are any numbers known?
Scientists have been thinking about the density of a black hole for a long time. Certain studies were carried out, attempts were made to calculate. Here is one of them.
The solar mass is 210^30 kg. A hole can form at the site of an object that is several times larger than the Sun. The density of the lightest hole is estimated at an average of 10^18 kg/m3. This is an order of magnitude higher than the density of the nucleus of an atom. Approximately the same difference from the average density level characteristic of a neutron star.
The existence of ultralight holes is possible, whose dimensions correspond to subnuclear particles. For such objects, the density index will be prohibitively large.
If our planet becomes a hole, its density will be approximately 210^30 kg/m3. However, scientists have not been able toreveal the processes as a result of which our space house can be transformed into a black hole.
About the numbers in more detail
The density of the black hole at the center of the Milky Way is estimated at 1.1 million kg/m3. The mass of this object corresponds to 4 million solar masses. The radius of the hole is estimated at 12 million km. The indicated density of the black hole at the center of the Milky Way gives an idea of the physical parameters of supermassive holes.
If the weight of some object is 10^38 kg, that is, it is estimated at approximately 100 million Suns, then the density of an astronomical object will correspond to the density level of granite found on our planet.
Among all the holes known to modern astrophysicists, one of the heaviest holes was found in the OJ 287 quasar. Its weight corresponds to 18 billion luminaries of our system. What is the density of a black hole, scientists have calculated without much difficulty. The value turned out to be vanishingly small. It is only 60 g/m3. For comparison: the atmospheric air of our planet has a density of 1.29 mg/m3.
Where do holes come from?
Scientists not only conducted research to determine the density of a black hole in comparison with the star of our system or other cosmic bodies, but also tried to determine where holes come from, what are the mechanisms for the formation of such mysterious objects. Now there is an idea of four ways for the appearance of holes. The most understandable option is the collapse of a star. When it becomes large, synthesis in the nucleus is completed,the pressure disappears, the matter falls to the center of gravity, so a hole appears. As you approach the center, the density increases. Sooner or later, the indicator becomes so significant that external objects are unable to overcome the effects of gravity. From this point on, a new hole appears. This type is more common than others and is called solar mass holes.
Another fairly common type of hole is a supermassive one. These are more often observed in galactic centers. The mass of the object in comparison with the solar mass hole described above is billions of times greater. Scientists have not yet established the processes of manifestation of such objects. It is assumed that a hole is first formed according to the mechanism described above, then neighboring stars are absorbed, which leads to growth. This is possible if the zone of the galaxy is densely populated. Absorption of matter occurs faster than the above scheme can explain, and scientists cannot yet guess how the absorption proceeds.
Assumptions and ideas
A very difficult topic for astrophysicists is primordial holes. Such, probably, appear from any mass. They can form in large fluctuations. Probably, the appearance of such holes took place in the early Universe. So far, studies devoted to the qualities, features (including density) of black holes, the processes of their appearance do not allow us to determine a model that accurately reproduces the process of the appearance of a primary hole. The models currently known are predominantly such that, if they were implemented in reality,there would be too many holes.
Assume that the Large Hadron Collider can become a source of formation of a hole, the mass of which corresponds to the Higgs boson. Accordingly, the density of the black hole will be very large. If such a theory is confirmed, it can be considered indirect evidence for the presence of extra dimensions. At present, this speculative conclusion has not yet been confirmed.
Radiation from a hole
The emission of a hole is explained by the quantum effects of matter. The space is dynamic, so the particles here are completely different from what we are used to. Near the hole, not only time is distorted; the understanding of a particle depends largely on who observes it. If someone falls into a hole, it seems to him that he is plunging into a vacuum, and for a distant observer, it looks like a zone filled with particles. The effect is explained by the stretching of time and space. The radiation from the hole was first identified by Hawking, whose name was given to the phenomenon. Radiation has a temperature that is inversely related to mass. The lower the weight of an astronomical object, the higher the temperature (as well as the density of a black hole). If the hole is supermassive or has a mass comparable to a star, the inherent temperature of its radiation will be lower than the microwave background. Because of this, it is not possible to observe her.
This radiation explains the data loss. This is the name of a thermal phenomenon, which has one distinct quality - temperature. There is no information about the processes of hole formation through the study, but an object that emits such radiation simultaneously loses mass (and therefore growsblack hole density) is reduced. The process is not determined by the substance from which the hole is formed, does not depend on what was sucked into it later. Scientists cannot say what became the base of the hole. Moreover, studies have shown that radiation is an irreversible process, that is, one that simply cannot exist in quantum mechanics. This means that radiation cannot be reconciled with quantum theory, and the inconsistency requires further work in this direction. While scientists believe that Hawking radiation should contain information, we just do not yet have the means, the capabilities to detect it.
Curious: about neutron stars
If there is a supergiant, it does not mean that such an astronomical body is eternal. Over time, it changes, discards the outer layers. White dwarfs may emerge from the remnants. The second option is neutron stars. Specific processes are determined by the nuclear mass of the primary body. If it is estimated within 1.4-3 solar, then the destruction of the supergiant is accompanied by very high pressure, due to which the electrons are, as it were, pressed into the protons. This leads to the formation of neutrons, the emission of neutrinos. In physics, this is called a neutron degenerate gas. Its pressure is such that the star cannot contract any further.
However, as studies have shown, probably not all neutron stars appeared in this way. Some of them are the remnants of large ones that exploded like a second supernova.
Tom body radiusless than more mass. For most, it varies between 10-100 km. Studies were carried out to determine the densities of black holes, neutron stars. For the second, as tests have shown, the parameter is relatively close to the atomic one. Specific figures set by astrophysicists: 10^10 g/cm3.
Curious to know: theory and practice
Neutron stars were predicted in theory in the 60s and 70s of the last century. Pulsars were the first to be discovered. These are small stars, the rotation speed of which is very high, and the magnetic field is truly grandiose. It is assumed that the pulsar inherits these parameters from the original star. The rotation period varies from milliseconds to several seconds. The first known pulsars emitted periodic radio emission. Today, pulsars with X-ray spectrum radiation, gamma radiation are known.
The described process of neutron star formation can continue - there is nothing that can stop it. If the nuclear mass is more than three solar masses, then the pointwise body is very compact, it is referred to as holes. It will not be possible to determine the properties of a black hole with a mass greater than the critical one. If part of the mass is lost due to Hawking radiation, the radius will simultaneously decrease, so the weight value will again be less than the critical value for this object.
Can a hole die?
Scientists put forward assumptions about the existence of processes due to the participation of particles and antiparticles. The fluctuation of the elements can cause the empty space to be characterizedzero energy level, which (here's a paradox!) will not be equal to zero. At the same time, the event horizon inherent in the body will receive a low-energy spectrum inherent in the absolute black body. Such radiation will cause mass loss. The horizon will shrink slightly. Suppose there are two pairs of a particle and its antagonist. There is an annihilation of a particle from one pair and its antagonist from another. As a consequence, there are photons that fly out of the hole. The second pair of assumed particles falls into the hole, simultaneously absorbing some amount of mass, energy. Gradually, this leads to the death of the black hole.
As a conclusion
According to some, a black hole is a kind of cosmic vacuum cleaner. A hole can swallow a star, it can even “eat” a galaxy. In many respects, the explanation of the qualities of a hole, as well as the features of its formation, can be found in the theory of relativity. It is known from it that time is continuous, as well as space. This explains why compression processes cannot be stopped, they are unlimited and unlimited.
These are these mysterious black holes, over which astrophysicists have been racking their brains for more than a decade.
