Generalized gravitational field equation and the basis of general relativity

Einstein's theory of relativity is a symbol of his lifelong career. In his paper entitled "On Electrodynamics of Moving Objects" published in 1905, he put forward the special theory of relativity completely, which largely solved the crisis of classical physics at the end of 19 and promoted the revolution of the whole physics theory. At the end of 19, physics is changing, and new experimental results are impacting the classical physics system established since Galileo and I Newton. The older generation of theoretical physicists, represented by H.A. Lorenz, tried to solve the contradiction between old theory and new things on the original theoretical framework. Einstein believes that the way out lies in fundamentally changing the whole theoretical basis. According to the relativity of inertial reference system and the invariance of light speed, he reformed the basic concepts of time, space and motion in classical physics, denied the existence of absolute static space and denied the absoluteness of the concept of simultaneity. In this system, the scale of motion should be shortened and the clock of motion should be slowed down. One of the most outstanding achievements of special relativity is to reveal the relationship between energy and mass. Mass (m) and energy (e) are equivalent: e = mc2 is a corollary of relativity. This can explain why radioactive elements (such as radium) can release a lot of energy. Mass-energy equivalence is the theoretical basis of atomic physics and particle physics, which satisfactorily explains the long-standing problem of star energy. Special relativity has become a basic theoretical tool to explain high-energy astrophysical phenomena.

After the establishment of special relativity, Einstein tried to extend the application of the principle of relativity to non-inertial systems. Starting from the experimental fact that Galileo discovered that the acceleration of all objects in the gravitational field is the same (that is, the inertial mass is equal to the gravitational mass), he put forward the equivalence principle in 1907: "The equivalent acceleration of the gravitational field and the reference system is completely equivalent in physics." It is concluded that in the gravitational field, the clock should go fast, the wavelength of light wave should change and the light should bend. After years of hard work, we finally established a general theory of relativity in 19 15, which is completely different from Newton's theory of gravity. Einstein calculated the abnormal precession of the perihelion of Mercury according to the general relativity, which is completely consistent with the observation results, and solved a major problem in astronomy for more than 60 years. At the same time, he concluded that the light emitted by distant stars will bend near the sun (see gravitational deflection of light). This prediction was confirmed by A.S. through solar eclipse observation in 19 19. 19 16 years, he predicted the existence of gravitational waves. After four years of continuous observation of the periodic changes of the radio pulse binary star PSR1913+16 discovered in 1974, the publication of 1979 indirectly confirmed the existence of gravitational waves, which is another powerful proof of general relativity.

After the establishment of the general theory of relativity, Einstein tried to expand it to include not only the gravitational field, but also the electromagnetic field. That is to say, he sought a unified field theory to explain the material structure and quantum phenomena with the concept of field. Because it was a difficult problem that could not be solved at that time, he worked for 25 years until his death. In 1970s and 1980s, a series of experiments strongly supported the theory of electric weak unification, and the idea of unified field theory revived in a new form. In history, only N. Copernicus, I. Newton and C. R. Darwin can compare with Einstein's contribution to scientific thought. However, Einstein did not confine his attention to natural science, but cared about society and politics with great enthusiasm. During World War I, he engaged in public and underground anti-war activities. 1933 After the Nazis seized the German regime, Einstein was the first persecuted object in the scientific community. Fortunately, he was giving a lecture in America at that time and was not killed. 1939 learned of the discovery of uranium nuclear fission and its chain reaction, and under the impetus of Hungarian physicist L. szilard, he wrote to President Roosevelt, suggesting to develop an atomic bomb to prevent the Germans from getting there first. So Roosevelt decided to build an atomic bomb and successfully tested it in New Mexico in 1945. On the eve of the end of World War II, the United States dropped atomic bombs over Hiroshima and Nagasaki, Japan, and Einstein was strongly dissatisfied with this. After the war, the United States waged unremitting struggles and launched a peaceful movement against the dangers of nuclear war and fascism. Einstein expressed deep sympathy for the sufferings of the working people in China at that time. After the September 18th Incident, he repeatedly called on other countries to stop Japanese military aggression against China by means of joint economic boycott. 1936, Shen Junru and other "seven gentlemen" were arrested for advocating anti-Japanese, and he enthusiastically participated in the just rescue and solidarity.