1905, Einstein wrote six papers in the patent office in his spare time. In April, May and June of 5438+February, three papers were about Brownian motion of suspended particles in liquid. He imagined that the actual size of molecules could be determined by observing the irregular motion of suspended particles caused by the fluctuation of molecular motion. This paper tries to solve the problem of whether atoms exist in the scientific and philosophical circles for a long time. Three years later, it was confirmed by the precise experiment of French physicist Perrin. In March, the paper "A Speculative Viewpoint on the Generation and Transformation of Light" applied Planck's quantum concept to the propagation of light, arguing that light is composed of light quantum, which is both fluctuating and granular. So Einstein won the Nobel Prize in Physics with 192 1 In June, he discussed the electrodynamics of moving objects. He put forward the special theory of relativity completely. Because of the historical achievements in these three different fields, he is destined to work in the academic institution of 1908. After the establishment of special relativity, Einstein was not satisfied and tried to extend the principle of relativity to non-inertial system. Starting from the fact that the gravitational masses are equal, Einstein founded the general theory of relativity in1915 ~1916 after years of hard exploration. Later, Einstein used the results of general relativity to study the space-time structure of the whole universe. 109 17 published a paper "He used scientific arguments to infer that the universe is finite and unbounded in space, which is a revolution in cosmology. In 2004, he and Indian physicist Bose put forward the quantum statistical theory of grassland gas, namely bose-einstein statistics. During the period from 1925 to 1955, Einstein went all out to explore the unified field theory. He tried to extend the general theory of relativity to include not only. It also includes electromagnetic field, that is, seeking unified field theory. Unfortunately, he never succeeded. However, since the 1970s, the idea of unified field theory has shown its vitality in a new form, pointing out the direction for the future development of physics.
Einstein's famous paper on special relativity
The further development of quantum theory One of Einstein's pioneering contributions is the development of quantum theory. Quantum theory is a hypothesis put forward by Planck in 1900 to solve the black body radiation spectrum. He believes that the energy released by an object when it emits radiation is not continuous but quantized. But most people, including Planck himself, dare not push the concept of energy discontinuity further, and even try to bring it into the classical physical system again and again. Einstein had a hunch that quantum theory brought not a small correction, but a fundamental change in the whole physics. 1905, he extended Planck's quantum concept to the propagation of light in space, and put forward the light quantum hypothesis, which holds that: for time average (that is, statistical average phenomenon), light behaves as fluctuation; For instantaneous values (i.e. fluctuations), light appears as particles (see quantum optics). This is the first time in history that the fluctuation of microscopic particles and the unity of particle properties, that is, wave-particle duality, are revealed. The later development of physics shows that wave-particle duality is the most basic feature of the whole microscopic world. According to the concept of light quantum, he successfully explained the empirical law of photoelectric effect which can't be explained by classical physics, and won the 192 1 year Nobel Prize in Physics. 19 16, he extended the quantum concept to the vibration inside the object, and basically explained the relationship between the specific heat capacity of the solid and the temperature at low temperature. 19 16 years, he continued to develop quantum theory and deduced blackbody radiation spectrum from N Bohr's concept of quantum transition. In this study, he combined the concepts of statistical physics with quantum theory and put forward the concepts of spontaneous emission and stimulated emission. From the basis of quantum theory to the concept of stimulated emission, it has a great influence on astrophysics. Among them, the concept of stimulated emission provided a theoretical basis for the booming laser technology in the 1960s.
Molecular motion theory Einstein explained Brownian motion with atomism in the article "Study on the Motion of Suspended Particles in Still Liquid Based on Molecular Motion Theory". This movement is the irregular movement of some tiny particles suspended in liquid, which was first discovered by R. Brown. Three years later, J.B. Perrin, a French physicist, confirmed Einstein's theoretical prediction with accurate experiments, thus solving the problem that the scientific and philosophical circles have debated for more than half a century about the existence of atoms, and making the atomic hypothesis a solid scientific theory.
As a symbol of Einstein's lifelong career, relativity is his theory of relativity. 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.