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Black hole 0 1:33 in the center of the Milky Way galaxy
black hole
The curvature of space-time is too great for light to escape.
This entry is a polysemous word with 27 senses.
Popular Science China | This entry is reviewed by the entry writing and application project of Popular Science China.
Review expert Wang Junjie
Black holes are celestial bodies existing in space in modern general relativity. The gravity of a black hole is extremely strong, which makes the escape speed in the event horizon faster than the speed of light. Therefore, "a black hole is a celestial body in the curvature of spacetime, which is too big for light to escape from its event horizon". [ 1][2][3]
19 16, German astronomer karl schwarzschild got the vacuum solution of Einstein's field equation by calculation. This solution shows that if the actual radius of a static spherically symmetric star is less than a fixed value, there will be a strange phenomenon around it, that is, there is an interface-"horizon". Once you enter this interface, even light can't escape. This fixed value is called schwarzschild radius. This "incredible celestial body" was named "black hole" by American physicist john archibald wheeler.
A black hole cannot be observed directly, but its existence and mass can be indirectly known, and its influence on other things can be observed. The information about the existence of a black hole can be obtained by the "edge information" of X-rays and γ-rays released by the friction caused by the acceleration brought by the gravity of the black hole before the object is sucked in. Inferring the existence of black holes can also be obtained by indirectly observing the orbits of stars or interstellar clouds, and the position and mass can also be obtained.
On April19th, Beijing time, 2 1, the first photo of human black hole appeared. [4] [5] The black hole is located in the center of a huge elliptical galaxy M87 in Virgo, 55 million light years away from the Earth, and its mass is about 6.5 billion times that of the sun. Its core area has a shadow, surrounded by a crescent-shaped halo. Einstein's general theory of relativity has been proved to be valid under extreme conditions. [6]
Chinese name
black hole
Foreign name
black hole
subject
General relativity, astrophysics, black hole thermodynamics
classify
Schwarzschild black hole, RN black hole, kerr black holes, KN black hole.
boundary
Event horizon, infinite redshift surface, dynamic horizon
quick
navigate by water/air
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evolutionary process
Two black holes devour each other.
A black hole is formed by the singularity of a scalar polynomial in the center and the divergence of the surrounding space-time, and its boundary is a one-way film that can only enter and exit: the event horizon, which is invisible within the event horizon. According to Einstein's general theory of relativity, when a dying star collapses, it will collapse toward the center, where it will become a black hole, devouring all the light and any matter in the neighboring universe.
The process of a black hole is similar to that of a neutron star: a star is preparing to die, and its core rapidly contracts, collapses and explodes under its own gravity. When all the core materials become neutrons, the contraction process stops immediately and is compressed into dense stars, and the inner space-time is also compressed. However, in the case of a black hole, because the mass of the star core is so great, the contraction process goes on endlessly, and even the repulsive force between neutrons can't stop. Neutrons themselves are ground into powder under the attraction of squeezing gravity itself, and the rest are substances with unimaginable density. Due to the gravity generated by high mass, anything near it will be sucked in by it. [7]
It can also be simply understood that stars usually only contain hydrogen at first, and hydrogen nuclei inside stars collide and fuse with each other at all times. Because of the great mass of stars, the energy generated by fusion competes with the gravity of stars to maintain the stability of star structure. Because of the fusion of hydrogen nuclei, a new element helium is produced, and then helium atoms also participate in the fusion, changing the structure and generating lithium. By analogy, according to the order of the periodic table of elements, beryllium, boron, carbon and nitrogen will be generated in turn, and the star will not collapse until iron is generated. This is because the iron element is quite stable, and the energy released when participating in the fusion is less than the required energy, so the fusion stops, and the iron element exists in the star, resulting in the lack of enough energy in the star to compete with the gravity of the massive star, which leads to the collapse of the star and eventually forms a black hole. It is called "black" because the gravity it produces makes it impossible for the surrounding light to escape. Like neutron stars, black holes are evolved from stars whose mass is dozens or even hundreds times larger than that of the sun.
When a star ages, its thermonuclear reaction has exhausted the fuel in the center and the energy generated in the center is running out. In this way, it no longer has enough strength to bear the huge weight of the shell. Therefore, under the heavy pressure of the shell, the inner core begins to collapse, and the matter will move inexorably to the center, until finally a star with nearly infinite volume and density is formed. When its radius shrinks to a certain extent (it must be smaller than schwarzschild radius), the space-time distortion caused by mass makes it impossible to shoot out even light-a "black hole" is born.
adhesion
Black holes are usually found because they gather around gas to produce radiation. This process is called accretion. The efficiency of high temperature gas radiating heat energy will seriously affect the geometric and dynamic characteristics of accretion flow. Thin disks with high radiation efficiency and thick disks with low radiation efficiency have been observed. When accretion gases approach the central black hole, their radiation affects the rotation of the black hole, which is the flow of the central expanding material system. Accretion is one of the most common processes in astrophysics, and it is precisely because of accretion that many common structures around us are formed. In the early universe, galaxies were formed when gas flowed to the center of gravitational potential well caused by dark matter. Stars are formed by gas clouds collapsing and breaking under their own gravity, and then absorbing the surrounding gas. Planets (including the earth) are also formed by the accumulation of gas and rocks around newly formed stars. When the central celestial body is a black hole, accretion will show its most spectacular side. Black holes not only accumulate matter, but also radiate particles through Hawking's evaporation process.
What happens if you are inhaled by a black hole?
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Black holes can not only destroy stars, but also revive them.
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What does a black hole look like? Scientists painted it 40 years ago.
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100 the universe and black holes in the eyes of liberal arts students
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Black holes stretch, tear and devour stars.
evaporate
Because the density of black holes is extremely high, we can know that density = mass/volume according to the formula. In order to make the density of a black hole infinite and the mass unchanged, it means that the volume of a black hole must be infinitely small to become a black hole. Black holes are death stars formed by the extinction of some stars. It has a large mass and a small body. However, on the day when the black hole will also perish, according to Hawking's theory, in quantum physics, there is a phenomenon called "tunneling effect", that is, although the field strength distribution of a particle is as strong as possible in a place with low energy, the field strength will still be distributed even in a place with quite high energy. For the boundary of a black hole, this is a barrier with quite high energy, but particles may still go out.
Hawking also proved that every black hole has a certain temperature, and the temperature is inversely proportional to the mass of the black hole. In other words, the big black hole has low temperature and weak evaporation; Small black holes have high temperature and strong evaporation, which is similar to violent explosion. It takes about 1x 10 66 years for the solar mass black hole to evaporate. A black hole equivalent to the mass of an asteroid will completely evaporate in 1x 10-2 1 sec. [ 1]
Astronomers first observed a black hole "burping twice"
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What happens if people fall into a black hole?
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sabotage
Black holes will give off dazzling light, shrink in size and even explode, spraying objects and giving off dazzling light. When British physicist stephen william hawking made this prediction in 1974, the whole scientific community was shocked.
Hawking's theory is an inspiration-led thinking leap. He combined general relativity with quantum theory. He found that the gravitational field around the black hole releases energy and consumes the energy and mass of the black hole.
Stars are swallowed up by black holes.
Suppose that a pair of particles will be produced at any time and any place, and the particles produced are positive particles and antiparticles. If this creative process happens near a black hole, two things will happen: two particles annihilate and one particle is sucked into the black hole. "A particle is sucked into a black hole": a pair of particles produced near a black hole, in which an antiparticle will be sucked into the black hole and a positive particle will escape. Because energy cannot be generated out of thin air, we assume that antiparticles carry negative energy and positive particles carry positive energy, and all the motion processes of antiparticles can be regarded as the opposite motion processes of positive particles. For example, an antiparticle sucked into a black hole can be regarded as a positive particle escaping from the black hole. In this case, particles with positive energy escape from a black hole, that is, the total energy of the black hole is less. Einstein's mass-energy equation E=mc2 shows that the loss of energy will lead to the loss of mass.
When the mass of a black hole is getting smaller and smaller, its temperature will get higher and higher. In this way, when a black hole loses its mass, its temperature and emissivity increase, so its mass loses faster. This "Hawking radiation" can be ignored for most black holes, because the big black hole radiates slowly, while the small black hole radiates energy very fast until the black hole explodes.
Expression form
According to British media reports, a new theory points out that the death mode of black holes may turn into white holes. In theory, white holes behave just the opposite of black holes-black holes keep swallowing matter, while white holes keep spraying matter. This discovery was first reported by a British magazine website, and its theoretical basis is the obscure theory of quantum gravity. [8]
A black hole with strong gravity.
The space-time distortion of stars changes the path of light, which is different from the path without stars. Light will deflect slightly inward near the surface of the star, which can be observed by observing the light emitted by distant stars during the solar eclipse. When the star collapses inward, the space-time distortion caused by its mass becomes very strong, and the light deflects inward more strongly, making it more difficult for photons to escape from the star. For a distant observer, the light becomes darker and redder. Finally, when the star shrinks to a certain critical radius (schwarzschild radius), its mass causes the distortion of space-time to become so strong that the light deflects inward so strongly that it cannot escape. In this way, if the light can't escape, other things are even less likely to escape and will be pulled back. That is to say, there is a set of events or a space-time region from which light or anything can not escape and reach distant observers. Such a region is called a black hole. Its boundary is called the event horizon, which coincides with the trajectory of light that just can't escape from the black hole.