19 15, schwarzschild adopted a solution about the distribution of spherical matter in general relativity. According to this solution, he found that space-time is so curved within this spherical radius that nothing can escape from this spherical radius, even light can't escape from this spherical radius. Therefore, black holes are "black", which cannot be observed and can only be found indirectly.
Black holes are formed by supernova explosions in the late evolution of massive stars. Generally, a star 30 times the mass of the sun will evolve into a black hole. According to schwarzschild radius's formula, the schwarzschild radius of the sun is 3000 meters, and the schwarzschild radius of the earth is 0.9 cm. Generally speaking, if the earth is compressed to 0.9 cm, it will become a black hole.
All along, the pictures of black holes we have seen are simulated by scientists with computers according to relevant theories. Until 20 19, the publication of the first black hole photo once again verified the correctness of Einstein's general theory of relativity.
Black holes are a phenomenon predicted by Einstein's general theory of relativity. Einstein paved the way for black holes to enter the scientific field with general relativity, which was not his real intention.
19 15, Einstein delivered a series of speeches on general relativity, claiming that space and time are a continuum and can be distorted by anything with mass. The result of distortion is gravity, that is, gravity is the result of space-time distortion, forcing everything, from light to planets, even apples falling from trees, to pass through space along a curved path.
When Einstein developed the general theory of relativity, it took him about ten years to approximate his own equations with a mathematical form called tensor calculus. Even the best scientists are puzzled by mathematics. However, this challenge did not stop Einstein's contemporary astronomer, a theoretical physicist named karl schwarzschild. Schwarzenegger is a realist in essence, but he is very good at dealing with theoretical concepts. When Einstein published an article on general relativity in 19 15, Schwarzschild was one of the first people to realize their importance.
Schwarzschild was a patriot in Germany, so when World War I broke out, he put down his astronomical research and chose to join the army. When he read Einstein's paper, he was fighting in Belgium, France and Russia. Nevertheless, Schwarzschild was attracted by the essence of general relativity and began to look for the exact answers to his equations. After being sent home for two months after a serious illness, Schwarzenegger was finally able to concentrate on his calculations. Shortly before the death of 19 16, Schwarzschild completed his work and published later in the same year: On the gravitational field of point mass in Einstein's theory became one of the pillars of modern relativity research, in which Schwarzschild put forward his solution to Einstein's unsolved equations.
When Einstein wrote down his general theory of relativity, he found a new way to describe gravity, that is, gravity is the result of space-time distortion. Matter and energy exist in the background of time and space, with three spatial dimensions and one time dimension. The mass of an object will distort the structure of time and space-the greater the mass of the object, the greater the influence on time and space. Just as bowling on a trampoline will stretch the fabric and make it droop, planets and stars will distort time and space-this phenomenon is called "short-line effect". Therefore, planets orbiting the sun will not be attracted by the sun; It just runs along the curved space-time deformation caused by the mass of the sun. The reason why planets never fall into the sun is because of the speed of planets. In short, "matter tells space-time how to bend, and space-time tells matter how to move."
Schwarzschild realized that the escape velocity of the surface of an object depends on its mass and radius. For example, the escape speed of the earth is about 1 1.2 km per second-this is the speed that the rocket must reach before leaving the earth. However, if the radius of a given mass can be made small enough, the escape speed will increase until it reaches the speed of light, that is, 300 thousand kilometers per second. At that time, neither matter nor radiation could escape from the surface of the object. In addition, atomic or subatomic forces cannot make an object bear its own weight. Therefore, the object collapses into an infinitesimal point-the original object disappears from the field of vision, leaving only its gravity to mark its existence. In this way, there will be a bottomless pit called singularity in the space-time structure. Schwarzschild also explained that a singularity is surrounded by a spherical gravitational boundary, which always traps anything that enters. This boundary is called the horizon. Schwarzenegger also proposed a formula to calculate the size of the horizon. This is schwarzschild radius, the edge of the bottomless pit of time and space. The schwarzschild radius of the sun is 3km, that is, its horizon is 3km away from its surface, and the schwarzschild radius of the earth is 9mm.
Schwarzschild's paper contains radical predictions. The idea of a bottomless pit in time and space has puzzled many scientists, including Einstein. Einstein himself did not believe in the existence of black holes. Although his own theory predicted the existence of black holes, he strongly opposed this view. 1939, Einstein published an article in Mathematical Yearbook, trying to prove that such a bottomless pit of time and space could not exist. Because it openly violates human experience-the world is limited and everything can be weighed and measured.
1967, john wheeler, an American physicist, improved Schwarzschild's original statement that "an object is completely collapsed by gravity" and named it a black hole. Scientists didn't realize its importance in the evolution of stars for about fifty years, and only recently did they realize its great influence on the development of the universe. Modern scientific knowledge is that black holes do exist and are one of the most important features of the universe. Astronomers have been able to detect them indirectly in different ways, so there is no doubt about their existence.
First of all, it should be clear that Einstein did not predict black holes. After Einstein published his special theory of relativity in 1905, he began to explore the theory of gravitational relativity for eight years from 1907. After many detours and mistakes, he gave a speech at the Prussian Academy of Sciences in June 19 15438+0, explaining how gravity works and giving the famous Einstein gravitational field equation:
The significance of the whole equation is that the energy and momentum distribution of space matter determines the bending state of space.
19 16, the German astronomer karl schwarzschild got the vacuum solution of Einstein's gravitational field equation by calculation. This solution shows that if a large number of substances are concentrated in a space, there will be a strange phenomenon around it, that is, there is an interface around the particles-once the "horizon" enters this interface, even light cannot escape. This "incredible celestial body" was named "black hole" by American physicist john archibald wheeler.
Einstein explained that there is mutual attraction between objects because the mass of objects distorts the space-time of the environment in which the objects are located, and this distortion forces all objects to cross the space along a curved path. This phenomenon was felt in our last observation that there is a related attraction between substances. For example, in our daily life, we see the phenomenon that apples fall from trees to the ground. Einstein gave an explanation: because of the existence of the earth, the space and time around the earth are distorted, and the apple just walks along the distorted space; Newton's solution: Everything in the world attracts each other, and the apple falls from the tree because of the gravity of the earth. Later, in astronomical observation, it was found that Einstein's theoretical calculation results were closer to the trajectory of celestial bodies, such as the calculation results of the annual difference of Mercury's perihelion. Karl Karl schwarzschild used Einstein's gravitational field equation to calculate a special existence, that is, according to the mass of an object, the space-time of its surrounding environment can be distorted, and the degree of distortion is directly proportional to its dynamic tensor Tuv. By calculating the karl schwarzschild, we can draw the following conclusion: when the dynamic tensor Tuv of a celestial body is large enough, the space-time of its surrounding environment is severely distorted, so that when light (the fastest object in the universe) approaches the celestial body for a certain distance, it cannot escape. Later, scientists named this celestial body a black hole.
In other words, Einstein just gave a method to explain the phenomenon of gravity, and karl schwarzschild used this method to calculate a special celestial body, which was named "black hole" by American physicist john archibald wheeler.
At 9: 00 p.m. Beijing time 10, astronomers from all over the world, including China, announced the "real content" of the black hole at the same time. This is the first time that human beings have photographed a black hole, which proves that Einstein's general theory of relativity is still valid under extreme conditions. 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, as shown above.