Why do we say Einstein is a great scientist?

Einstein's scientific achievements Wu Zhongchao Einstein is the greatest scientist in history after Newton. He is an important discoverer of special relativity, and he has made great contributions to the establishment of quantum theory, and the establishment of general relativity, that is, the modern theory of gravity, should all be attributed to him. At the end of the 19th century, Maxwell successfully unified electricity and magnetism in his electromagnetic theory, and deduced from his equation that the speed of electromagnetic wave propagation in vacuum is just the speed of light, so he concluded that light wave should be a kind of electromagnetic wave. Maxwell lived only 48 years old because of the family disease, so he didn't see the success of the electromagnetic wave experiment. In the framework of Newton's absolute space, absolute time and Galileo's old relativity principle, only objects moving at infinite speed have the same speed in the coordinate system with relatively uniform motion, that is, infinite speed. Newton's gravity is considered to be transmitted at infinite speed, so before Maxwell, Newton's physics was considered to be self-consistent, while electromagnetic waves propagated at finite speed. In the old framework of relativity, its speed would change because of the selection of coordinate system, so his equation could only be established in a specific coordinate system, which was considered to be static relative to a medium called ether. So seeking the existence of ether has become the theme of science. The results of Michelson-Morey experiment denied the existence of ether. Einstein published a paper entitled "electrodynamics of moving objects" in 195, pointing out that if time and space are composed of four-dimensional space-time, and the coordinates of space-time follow the so-called Lorentz linear transformation when the reference system is moving at a relatively uniform speed, all physical laws, including Maxwell's equations, should take the same form. In this way, the existence of ether is completely unnecessary. Whether Einstein knew about Michael-Morey's experiment before he published the special theory of relativity is still an unsolved case in the history of science. This paper abandoned Newton's absolute view of time and space, which led to a revolution in physics. The scaling, clock slowness and twin paradox derived from Lorentz transformation all contradict people's intuition. The famous formula of mass-energy equivalence is the theoretical basis of nuclear energy and even nuclear weapons. In 19, Planck put forward the quantum theory of radiation in order to solve the ultraviolet disaster of blackbody radiation, that is, optical radiation must take a wave packet form called quantum. But only after Einstein put forward the photon theory did people really accept that light can exist in the form of particles or photons. Planck was the reviewer of Einstein's first paper on special relativity. Since light waves can exist as particles, can particles of matter such as electrons exist as fluctuations? This is the idea of a French graduate student, De Broy, and Einstein immediately supported this radical hypothesis after learning about it. These are the prelude to the discovery of quantum theory. Einstein won the Nobel Prize in Physics for his photon theory. In fact, Einstein's contribution to relativity is far more important, but the Nobel Prize Committee is cautious about radical relativity. In fact, the Nobel Prize has never been awarded to a theoretical relativist. Throughout his life, Einstein never accepted quantum theory as the ultimate theory. He believed that quantum mechanics was only a phenomenological theory, and the ultimate theory must be decisive. We know that quantum mechanics is not self-consistent as far as the present situation is concerned. It is still suffering from Einstein-Rosen-Padol paradox. In recent years, some studies seem to have freed Schrodinger's cat paradox from its torture to some extent. Dirac combined the special theory of relativity with quantum mechanics and obtained a very fruitful quantum field theory. Quantum field theory is a theoretical framework to describe all microscopic particles. The concept of antiparticle can be deduced from Dirac equation. Quantum electrodynamics may describe the annihilation, creation and mutual transformation of electrons, photons and positrons. People then developed contemporary particle physics. Einstein said that if he doesn't publish the special theory of relativity, someone else will publish it within five years. In fact, Lorenz and Poincare were very close to this result at that time. It's a pity that Lorenz can't get rid of the old concept of time and space, and Poincare is mainly an outstanding mathematician, so only Einstein, who has a keen eye and deep thinking, takes this historical task. It is worth mentioning that Lorenz was a world-famous physicist at that time, and Poincare was the first mathematician in France. After Einstein graduated from university, he couldn't even find the position of a middle school teacher, so he worked as an employee in Berne Patent Office with the help of a friend's introduction. He went on to say that if he did not publish the general theory of relativity in 1915, people would have to wait at least fifty years. This estimate is very reasonable. General relativity is the result of the combination of special relativity and gravity theory. One of its experimental bases is Galileo's free fall experiment in the leaning tower of Pisa, that is, the equivalence of gravitational mass and inertial mass. But in order to fully explain its physical meaning, people waited for 3 years, that is, until the discovery of general relativity. So if it weren't for Einstein, it would be possible to wait another 5 years. When we browse the sixth volume of Einstein's collected works, we can see that he has made many unsuccessful attempts, which is a toddler of human reason. He believes that the gravitational field is different from other material fields, and it is embodied by the curvature of space-time. Matter bends space-time, which is the carrier of matter, and curvature of spacetime without matter is gravitational wave. The so-called principle of general relativity is that the laws of physics adopt the same form for any coordinate transformation, while the principle of special relativity is that the laws of physics only adopt the same form for any Lorentz linear transformation. The gravitational field is governed by the so-called Einstein equation. It is nonlinear and different from all previous field equations. So the equation of motion of matter is implied by Einstein's equation. The gravitational field equation is a second-order hyperbolic partial differential equations with elliptic constraints, with space-time as independent variable and metric as dependent variable. Its complexity and beauty leave a deep impression on anyone who has ever dealt with it. Within the framework of general relativity, Einstein calculated the gravitational redshift, the precession of Mercury perihelion and the refraction of light by gravitational field. His prediction that light is refracted near the gravitational field of the sun was confirmed by the observation of the solar eclipse in West Africa in 1919. His equations are so difficult that he only uses an approximate solution in these calculations, relying mainly on his incomparable physical insight. The exact solution of spherical symmetry-Schwartz solution was found only after this. He used the gravitational field equation to study the whole universe for the first time, which initiated a new discipline of theoretical cosmology. Unfortunately, because the concept of the steady universe is so deeply rooted, he refused the solution of the evolutionary universe, and he also introduced a cosmological constant into the field equation for this reason, thus human beings lost a major scientific prediction opportunity! In 1929, Hubble observed the linear relationship between the spectral redshift and the distance of galaxies, which is called Hubble's law. People attribute the redshift to the expansion of the universe and assert that the universe was produced by a big bang more than 1 billion years ago, which is the so-called standard big bang cosmology. His field equation also leads to the solution of gravitational collapse of compact objects, that is, Schwartz solution and its generalization, which is the solution describing black holes. But Einstein thought that matter could not be so compact, and wrote that it was absurd. However, history has proved that black holes are the most important objects in astrophysics. In recent years, astronomical observations have made people generally think that there are huge black holes in the center of galaxies. In fact, the universe itself and black holes are the most wonderful research objects of theoretical physics. If we put aside the universe and black holes, the glory of physics will be greatly inferior! Einstein made key contributions to Brownian motion, radiation theory as the basis of laser mechanism, Bose-Einstein statistics and its condensation phenomenon. The debate between him and Bohr about quantum mechanics is a long-lasting and far-reaching event in the history of science. He firmly believes that all interactions in nature can be unified into one function. Unified field theory is the diamond in the crown of science! The contemporary theories of supersymmetry, supergravity and superstring are all attempts to unify the field theory. Relativity has made great progress in recent forty years, especially classical relativity has become a mature discipline. The progress of relativity in modern times is mainly attributed to Penrose and Hawking. Penrose used global analysis and topological tools to give profound relativistic calculation a distinct physical meaning. penrose diagram named after him is as important to space-time as Feynman diagram is to particle physics. Hawking and Penrose proved the odd victory theorem together. He independently proved the black hole area theorem and that the black hole horizon area represents the entropy of the black hole. His black hole evaporation theory unifies quantum field theory, general relativity and statistical physics, and its theory is magnificent and dazzling like a Buddha's light. His boundlessness hypothesis of quantum cosmology is a scientific theory to study the creation of the universe. The author believes that the biggest motivation to guide Einstein and his descendants' career as scientists is not wealth, fame or other higher goals (especially wealth and fame can be obtained by other faster means). Their main motives are scientific curiosity and scientific aesthetics. We can find many examples in history, how many people just sacrificed their health, wealth and reputation in the secular world for science. But everything that people have in the whole world may be deprived except the joy of scientific discovery and artistic creation. Mankind's unremitting pursuit of curiosity and beauty will lead mankind to a better future! Written on the eve of Einstein's 12th birthday.