A black hole war, the mysterious black hole that can make Hawking lose the gambling contract, what is the origin?

I first saw the word black hole when I was eight years old. One day, my mother bought me a set of books with a hard paper shell. At that time, I thought it was too high. It was 1, books published by China Children's Publishing House in 198. Why?

It belongs to the famous publications in the publishing history of China, and each paragraph was written by academicians of the Chinese Academy of Sciences at that time. After I got this book, my first book was astronomy, so in the quiet and warm summer, I met the name black hole for the first time.

A black hole is a celestial body existing in the space of modern general relativity. The acceleration of gravity in space-time is so strong that the escape speed in the horizon is greater than the speed of light. It is a region or celestial body where no particle or electromagnetic radiation including light can escape.

as early as November 1784, John Mitchell, then the chancellor of Cambridge, wrote a letter to physicist cavendish, in which he suggested that there was a huge celestial body from which even light could not escape, but it was described by the word dark star.

In the early 2th century, physicists used the word gravitational collapse to describe black holes. In 196s, American physicist Robert Henry Dick compared this celestial body with a notorious prison, which was called Calcutta Black Hole, and the word black hole was officially released.

Later, life magazine and science news magazine used the term black hole in their publications in 1963, and the real development of this term was in the lecture given by physicist John Wheeler in December 1967. At that time, Wheeler thought that the term black hole was concise and had advertising value, so he adopted it and became a term, which made the term black hole quickly popularized. Therefore, some people mistakenly think that it is to put forward the name black hole.

In fact, every dark black hole once shone brilliantly in the universe, and once displayed the brilliance and brilliance of its life with great vigour. We know that most stars have a large number of hydrogen atoms, and nuclear fusion turns hydrogen atoms into helium atoms, which releases great energy.

It is this energy that exists in the form of thermal pressure radiation to counter the huge gravity. There is just a balance between these two forces, which supports the star from collapsing. Therefore, as long as the core continues nuclear fusion, the star can maintain sufficient stability.

When the core fuel runs out and the life of the star ends, the internal pressure of the star will drop due to cooling, which will lead to the collapse under the action of gravity. For those stars whose mass is much larger than that of the sun, the heat energy and pressure in the core can make them synthesize heavier elements, and eventually they may synthesize iron atoms.

However, it is worth noting that the process of producing iron atoms does not produce any energy. When iron nuclei accumulate in the center of massive stars to a certain extent, the balance between radiation energy and gravity collapses, and the iron shell collapses. In a few thousandths of a second, the star explodes itself and moves at 1/1th of the speed of light. This process is the death process of stars, that is, supernova explosion.

After the supernova explosion, the gravitational collapse forms a sphere close to the schwarzschild radius, and schwarzschild radius is the eigenvalue of a critical radius for any matter with mass.

In p>1916, German physicist Schwarzschild reached a conclusion by using Einstein's general theory of relativity. This theory was confirmed in 1971. When the actual radius of an object is smaller than that of schwarzschild radius, it becomes a black hole. The schwarzschild radius of the sun is about 3, meters, and the schwarzschild radius of our earth is only 9 millimeters. In other words, if you can compress the earth into a diameter of less than 1.8 cm, it becomes a black hole. It seems a bit beside the point. Then, just now, after the gravitational collapse formed a sphere close to schwarzschild radius, the arrangement of the nucleus was still there, and the structure of the atom was not destroyed, but the electrons were squeezed into the nucleus, protons and electrons were squeezed together to become neutrons, and then the whole collapsed structure stopped this state, that is, neutron type.

At this moment, if the mass of the neutron star is more than 3-4 times that of the sun, that is, the Oppenheimer volkov limit, the neutron star will continue to collapse under the action of gravity. When it is reduced to within the schwarzschild radius, the structure of the atom will be completely destroyed. At this time, there is no power to compete with the eyesight, and all substances will move crazily towards the center, eventually forming an infinitely small celestial black hole with infinite density.

gravitational collapse is not the only process that can form a black hole. In theory, a black hole can be formed in a high-energy collision with sufficient density, but the mass of the black hole must have a lower limit. Theoretically, it is expected that the boundary should be near Planck mass, but the development of quantum gravity shows that Planck mass may be very low, which may cause miniature black holes to be produced in a high-energy collision when cosmic rays hit the atmosphere. Or it may be produced in the Large Hadron Collider (LHC) of CERN (the world's largest particle physics laboratory).

Although CERN is the world's largest particle physics laboratory, it has the largest particle accelerator LHC with the highest energy in the world. In early August 219, CERN announced that the upgrade of the LHC's next-generation high-brightness large hadron collider project has begun. It is estimated that it will be officially put into operation in 226, and the equipment budget is 955 million Swiss francs, equivalent to about 6.7 billion RMB, even though the brightness of LHC will be improved by 5-1 times.

Back to the miniature black hole produced by the collision just now, many people are worried about whether the earth will disappear after hitting the black hole. Not really. Even if a miniature black hole can be formed, scientists predict that it will evaporate in about 1-25th second, and it will not pose any threat to the earth. If you are looking at this black hole, what you see is its event horizon. As predicted by the general theory of relativity, the existence of mass is the deformation of time and space, which makes the path of particles move towards the event horizon of the black hole with curved mass. This deformation is so strong that no path is far from the black hole. If anything wants to escape through this event, the speed must exceed the speed of light.

Einstein's theory of relativity points out that in any inertial coordinate, the speed of matter cannot exceed the speed of light in vacuum, so it is impossible. That is to say, everything including light can't reach the outside from the event horizon, so what you see is only a dark sphere that doesn't reflect any light, which is the black part of the hole. However, any matter of celestial bodies below schwarzschild radius, that is, all matter entering the event horizon, collapses into a point with infinite mass, infinite density and infinitesimal area, that is, the gravitational singularity.

At the singularity, the laws of space, time and physics that we know at present are no longer applicable. According to the description of general relativity, the starting point is an infinite area where the rate of time and space changes, just like a hole where hunger devours everything forever, which is the dark part.

black holes can't be seen. how did scientists find them?

Although we can't see anything in the event horizon of a black hole, scientists have found that the black hole is surrounded by particles formed by gas and dust by observing and studying the phenomena around it. These particles rotate around the black hole at a high speed at about 1/1th of the speed of light. Such a high-speed movement will lead to a continuous burst of radiation and produce ultra-high brightness, which is called accretion disk. The closer to the event horizon of the black hole, the faster the speed will be, and the more the black hole must bear.

Therefore, there is a supermassive black hole in the center of the largest and brightest accretion disk. This supermassive black hole exists in the center of almost every supermassive galaxy, such as our Milky Way. In 28, German astronomers confirmed that Sagittarius A, which is 26, light-years away from the Earth in the center of the Milky Way, is a supermassive push.

In addition, unlike a vacuum cleaner, a black hole sucks all the surrounding matter into the event horizon. When the matter approaches the edge of the black hole, the space-time around the matter is distorted into infinite curvature, which means that the range where the matter is located also becomes the horizon, which means that the horizon of the black hole expands and engulfs the matter.

for example, if we replace the sun with a black hole with the same mass, according to schwarzschild radius, the diameter of the black hole is about 6m, but at this time, the planets in the solar system will not be sucked in by the sun, but will still revolve around the black hole of the sun. Of course, humans will freeze to death.

in the 196s, the United States launched a series of sounding rockets for observation in preparation for landing on the moon. During a rocket ballistic flight in 1964, it was found that it was one of the strongest X-ray sources observed from the earth, namely Cygnus X-1, which was about 6,7 light years away from the earth, with its mass about 14.8 times that of the sun, and its event horizon radius was about.

It is called a candidate star because there are practical difficulties in observing black holes at present. It can't fully verify all the characteristics of black holes and can't meet the data requirements of professional astrophysics. Therefore, there are no black holes in the astronomical database. Strictly speaking, there are only candidate bodies of black holes, but for convenience, we call them black holes by default now, and later determined that Cygnus X-1 is a black hole, which is also the first black hole discovered by human beings.