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Black Hole

  • What does black hole mean?
  • The black hole, in astrophysics, is a massive cosmic body of mass that is powerful at the moment when the gravitational field will not allow any material formation and radiation to escape from itself. The black hole can also be called an object that comes into being with a certain amount of material in space, gathered at a spot. Such objects are called dark because they do not emit light.

 

  • Black holes are therefore considered to be zero volume, so they are not three-dimensional because of their “singularity“. It is estimated that the time in the black holes is slow activity or not. Black holes are defined by Einstein‘s general relativity theory. Not directly observable, they were discovered through indirect observation techniques using various wave lengths. At the same time, these techniques also allowed for the examination of entities that drifted in their surroundings. For example, because the potential of a black hole is too deep, the material that falls on the accumulation dentin that will form in the immediate vicinity will cause the dyes to reach very high temperatures, which will allow them to be detected by x-rays radiating from the dicent (and indirectly through the black hole).
  • Nowadays, the existence of black holes has been confirmed by virtually all individuals of the relevant scientific community (consisting of astrophysicists and theoretical physicists).

 

  • Black hole terminology
  • The black hole has a mass concentrated to a point called “gravitational singularity“. This mass constitutes a sphere centered on the so-called singularity of the “black hole” event. This sphere can also be thought of as the place where the black hole covers in space. The radius of a black hole equal to the mass of the Sun is only about 3 km.
  • When distances between stars (millions of kilometers) are in question, a black hole does not exert more gravitational force on any cosmic body than a cosmic body with the same mass as itself; That is, black holes should not be considered an irresistible cosmic “aspirator“. For example, if there was a black hole with the same mass in the place of the Sun, there would be no change in the orbits of theplanets in the Solar System.

 

  • There are many types of black holes. The black hole pattern formed by the collapse of a star in gravitational (on itself) is called “star black hole“. If these black holes are in the center of the galaxies, they can have a massive mass of up to a few billion “solar masses” and in this case they will be called “giant black holes” (or galactic black holes).

 

  • Among these twotypes of masses, which constitute the two extremes of black holes, it is thought that there is a third strand of masses of several thousand “solar masses“, which is called “medium black holes“.

 

  • The lowest-mass black holes are thought to have been formed in the Big Bang, which is the beginning of the history of the cosmos, and these are called “primary black holes“. However, the existence of the initial black holes has not yet been confirmed.

 

  • It is impossible to directly observe a black hole. In order to be able to see an object as it is known, it must reflect light from itself or light coming to it; Whereas black holes swallow the lights that pass very close.

 

  • His presence, however, is evidenced by the attraction of the surrounding environment, particularly because of the extremely high temperature of nearby matter that falls on the black hole in microcavities and active galaxy nuclei, and the strong emission of X-rays. Thus, observations reveal the existence of such objects in gigantic or tiny dimensions. The objects covered by these observations and fitting the general relativity theory are only black holes.

 

  • Black hole history
  • The concept of black hole could be first attempted at the end of the 18th century, under Newton’s universal gravitation law. But at that time the issue was only to know if there were masses at the time that would allow the “escape velocity” to be greater than the speed of light. The concept of a black hole therefore emerged only as a fantastic concept in the early 20th century, especially when Albert Einstein‘s general relativity theory was introduced. Shortly after the publication of Einstein’s work, Karl Schwarzschild published a solution containing the existence of a central black hole in the Einstein field equations.

 

  • Nevertheless, the first basic studies on black holes are based on the 1960s, following observations of the first solid statements about their existence. The first observation of a cismin with a black hole was made in 1971 by the Uhuru saturday. Cygnus, the brightest star of the constellation of Cypriot, identified the X-1 as an X-ray source on its twin. But the “black hole” was previously introduced by the American physicist Kip Thorne in the 1960s. The term “Schwarzschild body” and “closed star” were used for black holes before terminology settlement.

 

  • Black hole Properties
  • The black hole is an astrophysical object like other astrophysical objects. It is characterized by the fact that it is very difficult to observe directly and that the central region can not be defined satisfactorily with theories of physics. The most important factor in the inability to identify the central region is that it contains a “gravitational singularity” in its center.

 

  • This gravitational singularity can only be described by a “quantum attraction” theory, but such a theory is not available today. On the other hand, thanks to the various indirect methods applied, the physical conditions and the influence on the surrounding environment can be perfectly defined.

 

  • On the other hand, black holes are astonishing objects in that they are defined by very few parameters. The definitions in the world we live in depend on only three parameters: mass, electrical charge and angular momentum.

 

  • All other parameters (size, shape, etc.) of black holes are determined by them. In comparison, for example, in defining a planet hundreds of parameters are concerned (chemical composition, elemental differentiation, transport, atmosphere, etc.) Thus, since 1967, black holes have been defined by only these three parameters, which were discovered by Werner Israel in 1967 We owe it to the theory of absurdity.

 

  • This also explains the formation of long-range ground forces only of gravitation and electromagnetism; The measurable properties of black holes are only given by the parameters which define these forces, namely mass, electrical charge and angular momentum.
  • The properties of a black hole with mass and electrical charge are the usual properties to which the “classical” (no general relativity) physics can be applied:
  • Compared to the black hole mass, there is a “gravitational field” and an electric field relative to the electrical charge. The angular momentum effect, on the other hand, is peculiar to general relativity: some cosmic bodies that rotate around their own axis tend to “drag” (bend) the near space. This phenomenon called “Lense-Thirring effect” is not observed in our Solar System for the time being.

 

  • This phenomenon takes place in an unbelievable measure in the near space around the “spinning black hole” type around its axis, which is called “power zone” (ergorégion) or “power shaft“.

 

  • Classification of black holes according to rotation and load
  • There are three elements that determine all the properties of a deck: mass, angular momentum and electrical charge. The mass of a black hole is always greater than zero. It is possible to distinguish four types of black holes according to whether other elements are zero or greater than zero.
  • The black holes with zero angular momentum and electrical load are called “Schwarzschild black hole“. This name was dedicated in 1916 to Karl Schwarzschild, who proposed the idea of ​​the existence of such objects as solutions to the Einstein field equations.

 

  • If the black hole’s electrical charge is not zero and the angular momentum is zero, then the “Reissner-Nordström black hole” type would be the case. Since no known process makes it possible to produce a stuck object with such a continuous electrical charge, even if such black holes exist, they are not much of a focus in astrophysics. This electrical charge can be dispersed over time by absorbing the opposing electrical charges that would take it from the periphery. As a result, the “Reissner-Nordström black hole” is a theoretical body with little possibility of being present in nature.
  • If the black hole is an angular momentum and it does not have electrical charge (if it rotates around its axis), then the “Kerr black hole” type would be the case. This name was dedicated to the New Zealand mathematician Roy Kerr who had found the formula in 1963 to define such objects.

 

  • Unlike Reissner-Nordström and Schwarzschild black hole types, Kerr has become a major focus of interest for black-hole astrophysicists; Because the examples of the formation and evolution of black holes show that they tend to absorb the substance of their environment through a pile of discs and that the materials fall down by spiraling in the direction of rotation of the black hole into the accumulation disc. Thus, matter is in a relationship with the angular momentum of the black hole that swallowed itself. In this case, the black holes that the astronomer might be interested in are only Kerr black holes.
  • However, in cases where these black holes drastically weaken their angular momentum, it is naturally possible for them to resemble Schwarzschild black holes.
  • The fourth species is that Kerr black hole has electrical charge. This is called Kerr-Newman black hole type. There is little interest in this species as it is very unlikely to exist.

 

  • Black and hole
  • The existence of black holes was taken into account by John Michell and Pierre-Simon Laplace, unaware of each other, in the 18th century. At that time, the “escape speed” was supposed to be more than the speed of light, that is, the presence of cosmic objects that could not escape the influence of the light shots.

 

  • A change in the way the light is pulled through the hole is the effect of a force exerted under the influence of light (photons) gravitational fields, such as “Einstein equilibrium“, “slip to red” or “shift to gravitational red“. In this equilibrium or change caused by the gravitational field effect, the light loses its energy integrity while trying to get out of a “potential well” of a straw.
  • Here is an exchange of redemption in the nature that is somewhat different from that of the “expansion of the universe“, that is, from a space expansion observed in distant galaxies and without very deep “potential wells“.
  • This feature is well suited to the title “black” of the black hole, because a black hole does not emit light. Therefore, the name “black” is added to the name of the “black hole” objects.
  • This applies to matter as well as to light; Because no particle can escape from that black hole once it has begun to be pulled out of the black hole. This made the black hole called “hole“.

 

  • Event horizon
  • It is called “event horizon“, which limits the region where light and material can not escape. Event horizon is a piece of space we can not find in any physical review. There is no possibility of explaining beyond the event horizon by known laws, nor is there a way of knowing what is happening there. The event horizon of a star is proportional to the mass of the star before it collapses. For example, when a mass with 10 solar masses collapses into a black hole, the diameter is 60 km. Has an event horizon. As a black hole swallowing substance expands the event horizon, the event has a stronger attraction area as the horizon expands. In the event horizon of your black hole your time is theoretically entirely standing. There are two events in some black holes.

 

  • Some use the term “surface of black hole” rather than “black hole” rather than “black hole“. (The reason why the term is not appropriate is that there is no solid or gas-like surface, such as a planet or a star.) But here is not a region with particular qualities; An observer could have come close enough to overcome the black hole, he would not have felt any features or changes that would give him a surface impression. However, when he attempts to return, he will have realized that he can no longer escape from this region. This is a “point of no return“. This can be likened to the situation of a float in a strong sea, unaware of the current.
  • On the other hand, an observer approaching the limit of the event horizon will realize that the time differs from that of an observer far enough from the black hole. Assume that the observer far from the black hole sends light signals at regular intervals (for example, every second): Observers close to the black hole will be more energetic (the frequency of these light signals will be higher due to “blue shift” as the light approaches the black hole) The time interval between consecutive marks will be shorter (less than one second). The close observer will be monitoring the activity more quickly than in the distance. Unlike the distant observer, the other will see that things that are happening slower and slower, and will appear to be slower at times.

 

  • If a distant observer observes the fall of an object towards the black hole, the effects of “shifting to gravitational redness” and “expansion of time” will converge according to the observer: the signs of the object are increasingly reddish, increasingly fainter (light emitted by increasing energy loss before the distant observer) .

 

  • So in practice, the number of photons of light reaching the observer will gradually decrease and will be consumed after the object is buried in the black hole and is invisible. The remote observer who sees the object still standing still at the event horizon will be in vain to approach the event horizon to prevent its fall.

 

  • The effects that are beginning to affect an observer approaching the “singularity” of the black hole are called “tidal effects“. These effects lead to the object’s deformation (loss of its natural form) due to the inhomogeneous structure of the gravitational field. These “tidal zone” are all located in the event horizon in gigantic black holes; But especially in “stellar black holes“, which is beyond the bounds of event horizon.
  • An astronaut approaching the stellar black hole will eventually break apart before event horizon, an astronaut approaching the giant black hole will enter the event horizon without encountering any difficulty, with the “tidal effects” being destroyed later.

 

  • Singularity
  • At the center of a black hole is a region where the gravitational field and space bends (“slope“) become infinite. This region is called “gravitational singularity“.
  • This region has not been well defined in the framework of general relativity theory, since general relativity theory can not identify regions where the space-time slope is infinite. In fact, general relativity theory is not a theory that generally considers the effects of quantum-based gravitation. When the space-time curve is bent toward infinity, it necessarily depends on the effects of quantum nature. As a result, the only theory in which the gravitational singularities can be accurately described can be a gravitational theory that considers all the quantum effects.
  • Therefore, the definition of the gravitational singularity has not been made at present. However, it is known that if gravity enters the black hole and the entrained matter can not go out, the gravitational singularity does not affect the black hole as long as it is embedded in the black hole.
  • Although gravitational singularities continue to maintain their mysteries because of their inability to identify them and general theories of relativity are not sufficient to describe all gravitational phenomena, they do not constitute an impediment to defining them by moving from the event horizon on our side of our black hole.

 

  • Formation of black holes
  • The Death of Stars

Star Mass

Radius

Density

Last Product

small;”>Mstar< 0,8 Msun

 

10-103 gr/cm3

Brown dwarf or black dwarf

 

 

 

 

0,8 Msun< Mstar < 1,44 Msun

7000 km

106 gr/cm3

White dwarf

~1,35 Msun< Mstar<~2,1 Msun

10-20 km

8×1013-2×1015gr/cm3

Neutron Star

Mstar > ~3 Msun

4 km

>1016 gr/cm3

Black Hole

 

  • The possibility that black holes exist is not only a result of general relativity theory; Almost all other realistic physics theories about gravity are likely to see their existence.

 

  • The general theory of relativity, like other theories of gravitation, does not foresee the existence of black holes, but predicts that they will consist of matter trapped in a region of space.

 

  • For example, if our Sun had been compressed into a sphere with a radius of about three kilometers (that is, a volume of about four billionths of its size), it became a black hole. In fact, we could have constricted our Sun to a volume of 1cm3 (cubic centimeter), this time we would have made a 1cm³ of black hole.

 

  • But in this case there will be no change in the orbital movements of the planets in our system; That is, the planets in our Solar System will continue to spin in their orbits with this 1cm³ of black hole at the same gravity as the Sun. In another example, if our Earth were compressed into a volume of a few centimeters cubes, it would become a black hole.

 

  • In astrophysics, the black hole is treated as the final stage of a gravitational collapse. The ends of the evolution processes of the stars are determined by the mass they possess.

 

  • At the end of the evolutionary process, stars close to the mass, at the end of the compression of the material, according to their mass, there are two states; They become either white dwarf or become neutron stars that can later turn into black holes. In the dwarf, the dwarf is the degeneration of electrons that hold the balance of gravitation in balance.
  • In the case of neutron stars, nucleon corruption is not a matter of pressure, it is a “strong interaction” that provides equilibrium.
  • The black hole can not occur with collapse in relation to the black dwarf; During this collapse, very heavy nucleons form the star.
  • Energetic energy is enough to disperse the star.
  • But in the process of evolution, when the star at the threshold of transformation exceeds a certain critical mass (mass is large enough), a large black hole may be formed at the point where the gravitational force can overcome the pressure effect.
  • In this case, no known force is sufficient to maintain the balance and the object is completely collapsed. In practice, this can occur in many ways:

 

  • It can occur with the participation of a neutron star from another star until it reaches a certain critical mass.
  • It can occur by combining a neutron star with another neutron star (very rare, a priori a phenomenon).
  • A large star can be formed by collapsing the heart directly into a black hole.
  • A hypothesis about the existence of a substance more stuck in the 1980s than in the neutron stars has been raised. This was a stuck substance in the “quark stars”, also called “strange stars.”

 

  • In the meantime, from the 1990s onwards, clear findings could be obtained; But these findings have not changed what is known about a particular mass in the star species to complete the evolution by collapsing it into a black hole. What he’s changing is just the limit on the amount of mass.
  • In 2006, four classes of black holes were distinguished, depending on their mass: stellar black holes, gigantic black holes, medium black holes and primary (or micro) black holes.

 

  • Black holes by size
  • Star-shaped black holes
  • The stellar black holes have as much mass as a few solar masses. A dying star, if it is three times heavier than our Sun, can not remain at the level of a neutron star, the reaction and intensity of its nucleus continues to increase and becomes a “black hole“. The stellar black hole comes after gravitational collapse of the remains of a star (which is initially massive or more massive than about 10 solar masses). When the thermonuclear reactions in the heart of the star are finished burning, there is no fuel, so a supernova forms. This supernova can also leave a core that quickly collapses inside.
  • In 1939, Robert Oppenheimer revealed that if this core had a higher mass than a certain limit, the gravitational force would certainly carry itself over all other forces and a black hole would be formed.
  • The collapse to form a black hole is a good situation to spread “gravitational waves“, which are supposed to be detectable in the near future by some detector devices such as Virgo in Cascina (Italy) or the American LIGO “venture vehicle“. Star-shaped black holes are now observed in the “X double stars” and “microquartz“, and some “active galaxy nuclei” cause the formation of “flows” (Fr.jet).

 

  • Giant black holes
  • Giant black holes have a mass ranging from a few million to a few billion solar masses. They are located in the center of galaxies and their presence sometimes leads to the formation of “streams” and X-rays. Thus, these galaxy nuclei become brighter than normal brightness due to the superposition of stars, and are called “active galaxy nuclei”. Galaxy The Milky Way contains such a black hole, and it is this observation that observes that the stars near this black hole move extremely fast.
  • For example, one of these stars, the star of S2, was observed to have been around for at least 11 years in an unobserved dark object. The elliptical orbit of this star is about 20 astronomical units away from the dark object, and the dark object has a mass of about 2.3 million sun masses, though its limited volume. In addition to the black hole, an object with such a dense substance has not yet been encountered, despite its limited volume.
  • Observations made on the NGC 6240 galaxy with the Chandra telescope have also allowed the observation of two giant black holes revolving around each other in the center of this galaxy. The discussions about the formation of such giants are still going on, and according to some people they have formed very quickly at the beginning of the cosmos.

 

  • Medium black holes
  • Medium black holes have recently been discovered, with masses varying from 100 solar masses to 10,000 solar masses. In the 1970s, the hypothesis that medium-mass black holes occurred in global star clusters was raised, but no observations could be obtained to support this hypothesis. Observations of the year 2000 have revealed the presence of extra-bright or “extremely bright X-ray sources“.
  • These sources did not seem to be linked to the galaxy cores where giant black holes were found. Also, the amount of X-rays observed is too high to be produced by a 20-solar-black hole, given that matter participation is at a rate equal to the “Eddington limit” (the maximum limit for a stellar black hole) …

 

  • Primary black holes
  • Micro black holes or “primary black holes“, also called quantum black holes, are black holes that are very small in size. The reason for giving them the name “primitive” is that they are supposed to be formed during the Big Bang. In the “primitive cosmos“, it is thought that small-scale over-condensation occurs with gravitational pull-in.
  • In the 1970s, famous physicists Stephen Hawking and Bernard Carr were investigating the formation mechanism of black holes in the initial cosmos, and by developing the concept of black holes, they were the result of the abundance of extremely small black holes called “mini black holes” compared to the star black holes.
  • Although the intensities and distributions of these black holes are not yet known, it is believed that the determinants of these are related to the conditions of the rapid expansion of the initial cosmos, or “cosmic bulge“. These small mass black holes – that is, they need to emit a gamma ray. Radiations will probably be discovered by satellites like INTEGRAL.
  • According to some physicists working on high-energy physical specimens, smaller analogous examples of these black holes can also be created in the laboratory using a “particle accelerator” such as the LHC near Geneva.

 

  • Observation of black holes
  • There are many observational equipment for only two types of black holes (not direct, but indirect observations, progressing toward increasingly clear and selective observations, as seen in the following section): These are stellar black holes and giant black holes. The closest giant black hole is at the center of our galaxy, about 8 kilos away.
  • One of the first methods of finding a black hole was to determine the masses of two components of a pair of stars (two comrades) by referring to the orbit parameters. Thus, the components that were less massive than the other stars invisible from the binary stars were investigated, paying attention to their speed in the orbit.
  • From the components it can be interpreted as a neutron star or a black hole, as the mass is big and invisible, as normally a star in such a mass should be easily visible. Then, if the orbicular angle is not known, it is checked whether the comet’s mass has passed the maximum mass limit of the neutron stars (about 3.3 solar masses). If it crosses the border it is a black hole, if not it may be a white dwarf.

 

  • In addition, the knowledge that some of the stellar black holes found during the “publication of the waves of the gamma rays” is taken into account. Already such black holes can be formed by the explosion of a large star in the supernova (like the Wolf-Rayet star), and in some cases defined by the example of the “collapsar“, a black hole occurs when a gamma ray wave is produced.
  • Thus, a “gamma ray wave broadcast” (GRB) may be a sign of the birth of a black hole. Smaller black holes can also be formed by supernovas. For example, residues from the 1987A supernova are thought to have turned into a black hole.
  • Another phenomenon that shows the existence of a black hole is the existence of “flows” that are mainly observed in the field of radio waves, which can be created both as stellar black holes and as gigantic black holes.
  • These flows are caused by the large-scale magnetic field changes that occur in the “black hole” of the black hole.

 

  • Probability of direct observation
  • The smallness of a black hole makes direct observation difficult, for example, it is impossible to directly observe black holes of several kilometers.
  • Consider a black hole whose angular diameter is slightly larger than this; The angular diameter of a black hole that is as massive as 1 “solar mass” and is in the distance of a parsec (about 3.26 light years) will be only 0.1 microseconds, which gives an insight into the impossibility of observation.
  • In contrast, the position of giant black holes seems to be more favorable for direct observation. The size of a black hole is proportional to its mass.
  • The mass of a black hole at the center of a galaxy is an average of 2.6 million solar masses. Its “Schwarzschild radius” is also about 7 million km. Happens.
  • Assuming that this black hole is at a distance of 8.5 kilograms, the angular diameter is 30 microseconds. This result suggests that it is still very difficult to observe the cismin in the “visible light field“, but nowadays the “radio interference device” is not far from the detection limits.

 

  • Today, the sensitivity of radio interference devices based on frequencies in the millimetric range is increasingly being improved.
  • Any gain in the magnitude of the frequency domain, rather than the magnitude of the angular extent of the black hole, will provide us with a much more convenient means of observing the darkness.
  • At this point, it is not a very distant dream to get images of a black hole in the center of a galaxy with this technique. The black hole in the center of the M87 galaxy is 1300 times larger than it was 2000 times farther than the black hole mentioned above. Perhaps this black hole will be the second black hole in the future, the image of which will be acquired after the galaxy’s black hole in the Milky Way.

 

  • Examples of stellar black holes
  • Cygnus X-1, found in 1965, is the first known astrophysical cistern to contain a black hole. It was a double star system consisting of a rotating black hole and a red giant.
  • If the black hole is part of a double star system, then there is a flow of matter from the normal star to the black hole. The flow of matter creates a disc called a “stacked disc” around the black hole, depending on the principle of angular momentum conservation. This disc exposes X-rays near the black hole, reaching great temperatures under great gravitational potential and allowing the black hole to be spotted on our side.
  • Binary star systems with a black hole or a neutron star forming “flows” with a “helium disk” are called microquakers, denoting quasars that can be called extragalactic parents.
  • In fact, objects in both classes follow the same physical processes. One of the most studied microcircuits is GRS 1915 + 105, which was discovered in 1994 and is a “light-fast” “flow“.
  • Another system with such flows is GRO J1655-40. But since the distance of these two is still controversial, there is also the possibility that their flow may not be as fast as the light.
  • Another one is the SS 433, which is a very special microchip. It has such steady flows that the mass of material is displaced by the mass of the pile at the speeds around the speed of light.

 

  • Giant and medium black hole examples
  • Giant black hole candidates are primarily the “active galaxy nuclei” and the quasars discovered by radioastronomists in the 1960s. Observations that made the greatest evidence for the existence of gigantic black holes were observations on the orbits of the stars around the galactic center Sagitariusa.
  • Observations about the orbits and velocities of these stars showed that there could be no cosmic cistern other than the giant black hole in that region of this “galactic center“. After this reconnaissance, other galaxies were found to contain other black holes.
  • In February 2005, it was observed that a giant blue star named SDSS J090745.0 + 24507 was traveling at a rate twice as fast as the galaxy escape rate, that is, the speed of light was up to 0.0022, leaving the Milky Way galaxy. When the speed and trajectory were examined, it was understood that a huge black hole was thrown by gravity.
  • In November 2004, a group of astronomers announced that the galaxy had discovered the first black hole with medium mass.
  • This black hole, which was only three light years away from the center of the orbital galaxy, had a mass of 1300 solar masses and only a star cluster of seven stars.
  • This star cluster was probably the remains of a set of stars that once formed large stars and were crushed by a central black hole.
  • This observation supports the view that the giant black holes, the stars around them, and other black holes grow bigger.
  • All of this will probably be confirmed soon by means of a “space intervention” tool called LISA, which can be confirmed by direct observation of the subject’s gravitational waves.
  • In June 2004, astronomers discovered a giant black hole called Q0906 + 6930 at the center of a galaxy at a distance of 12.7 billion light years.
  • Given the Big Bang, this observation shows that the rapidity of the formation of gigantic black holes in galaxies is a relative phenomenon.

 

  • Theories of singularity
  • One of the main issues about black holes is the circumstances under which they are formed. Early times were thought to be very few chances of many because the formation conditions of black holes were so special.
  • But a number of mathematical theorems that we owe to Stephen Hawking and Roger Penrose showed that it was not at all.
  • Black holes could be formed on very different conditions and showed a variety. The work and theories of these two scientists, which do not leave much room for doubt, are called “theories of singularity“.
  • These theories have been put in place at the beginning of the 1970s, when no observations have yet been made confirming the existence of black holes. Subsequent observations confirm that black holes are indeed very common objects in the environment.
  • Naked singularities and cosmic censorship
  • In the center of a black hole is the “gravitational singularity”. In all types of black holes, this singularity is “hidden” from the outer world by “event horizon“. Today’s physics does not know how to define gravitational singularity.
  • But this does not carry much importance; Because this singularity lies within the bounded boundaries of the “event horizon” and does not affect the events of the outer world.
  • However, there is a mathematical solution to the “general relativity” equations in which a singularity exists without being surrounded by a horizon, as if the kinetic load or “kinetic moment” exceeds a certain value, as in Kerr or Reissner-Nordström solutions … In such a case It is no longer possible to speak of a black hole (no more horizon, no “hole”), but “naked singularity”. Examination of such conditions, which are determined by parameters, is extremely difficult in practice; Because we can not predict the singularity environment.
  • We can not say much about the issue of naked singularity with our current universe knowledge, or at least, until the 1990s, it was not possible to say much in this regard.
  • Until then, the Kerr or Reissner-Nordström black holes were thought to have no such critical value through the external contribution of the kinetic momentum or electrical charge.
  • Because, in short, it was thought that the burden / mass relation of the black hole would always reach “saturation” before reaching the exact critical value, and thus never reach critical value.
  • These basic concepts and considerations led the British mathematician Roger Penrose in 1969 to put forward the hypothesis of “cosmic censorship“.
  • This hypothesis suggested that no physical process would allow naked singles to emerge in the cosmos.
  • This hypothesis, which contains a number of possible explanations / formulas, was the subject of the assertion of Stephen Hawking with Kip Thorne and John Preskill, who argued that naked singularities could form at the stage. Finally in 1991, Stuart L. Shapiro and Saul A. Teukolsky demonstrated through numerical simulation that naked singularities could occur at the scene.
  • A few years later, Matthew Choptuik revealed other ways in which naked singularities could occur. Nevertheless, these proof-studies are not fully sufficient to ensure that the naked singularities are formed at the scene, since there is lack of observation. In this case, the issue can be summarized as follows:
  • Yes, it is possible that there are naked singularities in the scene, but it is doubtful that they exist in practice. Finally, Stephen Hawking confessed in 1997 that he had lost the claim that he had once entered Kip Thorne and John Preskill.

 

  • Entropy of black holes
  • In 1971, the British physicist Stephen Hawking showed that whatever the black hole, the surface of the “event horizon” never diminished. This property resembles the “second law of thermodynamics” in terms of the surface that plays the role of entropy (dissolution, dispersion, disappearance).
  • In the context of classical physics, this law of thermodynamics can be violated by submitting matter to a black hole, thereby ensuring that it disappears in our cosmos.
  • The physicist Jacob Bekenstein suggested that the black hole (along with the unconfirmed vernacular) has an entropy proportional to the surface of the horizon. Bekenstein was led by the fact that the black hole radiation did not radiate and that the relationship to thermodynamics was only a similarity, not a physical description of its properties.
  • Shortly after that, however, Hawking showed that it is possible to define a heat related to the enthalpy of enthalpy of black holes, rather than a simple analogy, based on the “radiation of black holes” (Hawking radiation), with a calculation based on the “quantum field theory”.
  • When the thermodynamic equations of black holes are used, it seems that the entropy of the black hole is proportional to the surface of the horizon.
  • This is a universal result that can also be applied in the context of “cosmological examples” containing a horizon such as “de Sitter universe“.
  • On the other hand, the disclosure of entropine in terms of the “microcannon community” remains an unsolved problem, although “string theory” has been able to achieve partial responses …
  • He then showed that black holes are the entropy bodies of the maximum, that is, the entropy of a space bounded by a certain surface is equal to the entropy of a black hole with the same surface.
  • This determination led Gerard ‘t Hooft and later Leonard Susskind to put forward the concept of “holographic principle” before the physicists.
  • The same principle can be explained as follows: If a hologram can encode information about a volume on a simple surface, and if it can thus effect a three-dimensional relief effect on the surface, the definition of the surface of a region in the distance also allows to reconstruct all information about the content of that region .
  • The discovery of the entropy of black holes thus allows the establishment of extremely deep affinity relations between black holes and thermodynamics and the “thermodynamics of black holes“, which can help to understand the theory of quantum attraction.

 

  • Evaporation of black holes (disappearance) and Hawking radiation
  • Although black holes are the most stable and longest-lived objects in the world, they can not live forever, they lose their energy very slowly by making Hawking radiation. Hawking radiation is not a radiation that can be detected with any technology.
  • In 1974, Stephen Hawking applied the “quantum field theory” to “curvilinear” teleportation of “general relativity” and discovered that, contrary to what is predicted by classical mechanics, black holes actually emit radiation (a radiation near thermal radiation), now known as “Hawking radiation” .
  • The black holes were not entirely “black” at this time, so they had something in them. But black holes, according to our current knowledge, can not make any other radiance because of their characteristics, because the escape speed on their surface is higher than the speed of light. If we could burn a lantern on the surface of the black hole, it would bend back to the black hole surface with the effect of the flashlight.
  • Hawking radiation corresponds to the spectroscopy of a “black body“. In this case, the heat inversely proportional to the size of the black hole could be associated with it.
  • In this respect, as the black hole grows in quantity, the heat falls. A black hole as massive as the Mercury planet has an equal heat (about 2.73 kelvin) to the CMB radiation (an electromagnetic radiation type).
  • The relationship between black hole mass, heat, energy loss, and Hawking radiation causes the temperature to gradually decrease as the mass of the black hole increases.
  • Thus, the temperature of a stellar black hole drops to a few microcelsels, making it more and more impossible to determine directly the “evaporation” (disappearance, Hawking radiation).
  • Nonetheless, in black holes, where mass is not very large, the heat is higher and the energy loss associated with it allows the understanding of the changes in mass in cosmological steps. Thus, a black hole of several million tons will evaporate in less time than the “present age of cosmos“.
  • The black hole will also become smaller when it “evaporates“, and therefore the heat will increase. Some astrophysicists think that black holes will produce a gamma ray wave under “evaporation” altogether.
  • This implies the confirmation of the presence of small mass black holes. In this case, the existence of “primary black holes” comes into question. Today, this possibility is being investigated on the data provided by the European adaptation INTEGRAL.

 

  • Information paradox
  • One of the main unsolved physics issues since the beginning of the 21st century is the famous information paradox.
  • It is not possible to determine as a posteriori those who entered the black holes because of the theory of “losslessness.” However, if it is considered from the perspective of an observer far away from the black hole, the information can not be totally destroyed because the matter in the black hole at the time, , It can still be seen by the observer.
  • Is the information forming the black hole in this case a loss or not?
  • The minds of this subject, who are supposed to have a “quantum attraction theory“, suggest that there may be a limited and finished quantity of entanglement of the black hole just near the horizon. Whilst all kinds of entropy of matter and energy in the black hole are taken into consideration, the variability of “Hawking radiation” seems to be far more satisfactory than the variability of horizon entropy. Nevertheless, many issues remain unexplained, especially with regard to quantum.

 

  • Wormholes
  • General relativity shows that the black holes in the state are in some way in contact with each other. In this structure, the corridors connecting the black holes to each other are referred to as “wormholes” (wormholes), wormholes or rare Einstein-Rosen holes with their usual name. According to this idea, black holes are opening up to another house, or doors to this second house.
  • The corridors, which link the black holes together, are called “wormholes” because they are thought to resemble the ridiculous path in a hand.
  • Given that there are many black holes in the scene, the result is that space is made up of numerous interconnected tunnels. These wormholes, which allow “bouncing” in cosmosis, without regard to time and light-year distances, have been a source of inspiration for unwritten sci-fi writers.
  • In astrophysical context, in practice, journeys in these tunnels seem to be impossible for now, with this structure full of cosmic tunnels confirmed by general relativity; Because no known process seems to be able to discern the formation of objects that can make these journeys.

 

Black Hole
Author: wik Date: 4:03 pm
Science and Mathematics


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