Einstein (1879- 1955) was a German Jew. He founded the theory of relativity, which represents modern science, laid a theoretical foundation for the development of nuclear energy, and initiated a new era of modern science with its far-reaching influence and wide application. He is recognized as the greatest scientist and thinker since Galileo and Newton. 192 1 Nobel Prize winner in physics.
1905 miracle
From 65438 to 0905, Einstein created an unprecedented miracle in the history of science. This year, he wrote six papers. During the half year from March to September, he made four epoch-making contributions in three fields in his spare time besides working eight hours a day in the patent office. He published four important papers on quantum theory of light, molecular size measurement, Brownian motion theory and special relativity.
1905 In March, Einstein sent the paper he thought was correct to the editorial department of the German Journal of Physics. He said shyly to the editor, "I will be very happy if you can find room for me to publish this paper in your annual report." This "embarrassing" paper is called "a speculative view on the generation and transformation of light".
In this paper, the quantum concept put forward by Planck in 1900 is extended to the propagation of light in space, and the optical quantum hypothesis is put forward. It is considered that: for time average, light behaves as fluctuation; For instantaneous values, light appears as particles. This is the first time in history to reveal the unity of fluctuation of microscopic objects and particles, that is, wave-particle duality.
At the end of this article, he explained the photoelectric effect with the concept of optical quantum, and deduced the relationship between the maximum energy of photoelectrons and the frequency of incident light. This relationship was not confirmed by Millikan's experiment until 10 years later. 192 1 year, Einstein won the nobel prize in physics for his achievement of "the discovery of the law of photoelectric effect".
This is just the beginning, Albert? Einstein went hand in hand in the three fields of light, heat and electrophysics, and it was out of control. 1905 In April, Einstein completed a new method to determine the molecular size, and in May, he completed the movement of suspended particles in still liquid required by the theory of thermomolecular motion. These are two papers about Brownian motion. Einstein's purpose at that time was to determine the actual size of molecules by observing the irregular motion of suspended particles caused by the fluctuation of molecular motion, thus solving the problem of whether atoms exist in scientific and philosophical circles for more than half a century.
Three years later, French physicist Perrin confirmed Einstein's theoretical prediction with accurate experiments. This justifies the objective existence of atoms and molecules, which also makes ostwald, the German chemist who is most firmly opposed to the founder of atomism and energy theory, take the initiative to announce in 1908 that "the atomic hypothesis has become a scientific theory with a solid foundation".
1In June, 905, Einstein finished his long paper "On Electrodynamics of Transport Bodies" which initiated a new era in physics, and put forward the special theory of relativity completely. This is the result of Einstein's brewing and exploration in 10, which largely solved the crisis of classical physics at the end of 19, changed the space-time view of Newtonian mechanics, exposed the equivalence of matter and energy, and created a brand-new world of physics, which is the greatest revolution in the field of modern physics.
Special relativity can not only explain all phenomena that classical physics can explain, but also explain some physical phenomena that classical physics can't, and predict many new effects. The most important conclusion of the special theory of relativity is that the principle of conservation of mass has lost its independence and merged with the law of conservation of energy, so that mass and energy can be transformed into each other. Others include the slow scale of the clock, the constant speed of light, the zero rest mass of photons and so on. Classical mechanics has become the limit case of relativistic mechanics at low speed. So mechanics and electromagnetism are unified on the basis of kinematics.
1905 In September, Einstein wrote a short article, is the inertia of an object related to the energy it contains? ",as an inference of relativity. Mass-energy equivalence is the theoretical basis of nuclear physics and particle physics, and it also paved the way for the release and utilization of nuclear energy in the 1940s.
In this short period of six months, Einstein's breakthrough achievements in science can be said to be "unprecedented". Even if he gave up physics research, even if he only accomplished any of the above three achievements, Einstein would leave an extremely important mark on the history of physics development. Einstein dispelled the "dark clouds in the clear sky of physics" and ushered in a more brilliant new era of physics.
Exploration of general relativity
After the establishment of the special theory of relativity, Einstein was not satisfied and tried to extend the application of the principle of relativity to non-inertial systems. He found a breakthrough from Galileo's discovery that the acceleration of objects in the gravitational field is the same, and put forward the equivalence principle in 1907. This year, Minkowski, his university teacher and famous geometer, put forward the four-dimensional spatial representation of special relativity, which provided a useful mathematical tool for the further development of relativity. Unfortunately, Einstein didn't realize its value at that time.
The discovery of the principle of equivalence was regarded by Einstein as the happiest thought in his life, but his later work was very hard and he took a big detour. 19 1 1 year, he analyzed the rigid rotating disk and realized that Euclidean geometry in the gravitational field was not strictly effective. At the same time, it is found that Lorentz variation is not universal, and the equivalence principle is only effective in an infinitesimal region. At this time, Einstein already had the idea of general relativity, but he still lacked the necessary mathematical foundation to establish it.
19 12, Einstein returned to his alma mater in Zurich. With the help of his classmate Grossman, a professor of mathematics at his alma mater, he found a mathematical tool to establish general relativity in Riemannian geometry and tensor analysis. After a year of hard cooperation, they published an important paper "Outline of General Relativity and Gravity Theory" in 19 13, and put forward the gauge field gravity theory. This is the first time to combine gravity with scale, which makes Riemann geometry have real physical significance.
However, the gravitational field equation they got at that time was covariant only for linear transformation, and it was not covariant under any coordinate transformation required by the principle of general relativity. This is because Einstein was not familiar with tensor operation at that time, and mistakenly thought that as long as the conservation law was observed, the choice of coordinate system would be limited, and in order to maintain causality, the requirement of universal covariation would be abandoned.
The second peak of scientific achievements
The three years from 19 15 to 19 17 were the second peak of Einstein's scientific achievements, similar to 1905, and he also made historic achievements in three different fields. Except for the general theory of relativity, which is recognized as one of the greatest achievements in the history of human thought, it was finally established in 19 15. 19 16 put forward gravitational wave theory in radiation quantum, and 19 17 started modern cosmology.
19 15 After July, Einstein returned to the requirement of covariation after more than two years of detours. From June 19 15 to June 1 10, he concentrated on exploring new gravitational field equations. On June 165438+ 10/0/4,1kloc.
In the first paper, he obtained the universal covariant gravitational field equation satisfying the conservation law, but added an unnecessary restriction. In the third paper, according to the new gravitational field equation, the deflection of light passing through the surface of the sun is calculated to be 1.7 arc seconds, and the precession of Mercury's perihelion is calculated to be 43 seconds every 100 years, which completely solves a major problem in astronomy for more than 60 years.
In his paper Gravitational Field Equation on 19 1 15125 October, he gave up unnecessary restrictions on transformation groups, established a truly universal covariant gravitational field equation, and declared that general relativity was finally completed as a logical structure. 19 16 In the spring, Einstein wrote a summary paper "The Basis of General Relativity"; At the end of the same year, a popular booklet "On Special and General Relativity" came out.
19 16 In June, when Einstein was studying the approximate integral of the gravitational field equation, he found that a mechanical system would inevitably emit gravitational waves propagating at the speed of light when it changed, and thus put forward the gravitational wave theory. 1979, 24 years after Einstein's death, the existence of gravitational waves was indirectly proved.
19 17 years, Einstein used the achievements of general relativity to study the space-time structure of the universe and published a groundbreaking paper, "A Survey of the Universe Based on General Relativity". This paper analyzes the traditional concept of "the universe is infinite in space" and points out that it is incompatible with Newton's theory of gravity and general relativity. In his view, the possible way out is to regard the universe as a closed continuous area with limited space volume and infer that the universe is infinite in space with scientific arguments. This is a bold pioneering work in human history, which makes cosmology get rid of pure speculation and enter the field of modern science.
A long and difficult exploration
After the completion of the general theory of relativity, Einstein still felt dissatisfied, so he wanted to extend the general theory of relativity to include not only the gravitational field, but also the electromagnetic field. He believes that this is the third stage of the development of relativity, namely the unified field theory.
After 1925, Einstein went all out to explore the unified field theory In the first few years, he was optimistic that victory was in sight; It turned out to be a lot more difficult. He thinks that the existing mathematical tools are not enough. Exploration of 1928 to pure mathematics. He tried various methods, but he didn't get any results with real physical significance.
During the 30 years from 1925 to 1955, except for the completeness of quantum mechanics, gravitational waves and general relativity, Einstein devoted almost all his scientific creative energy to the exploration of unified field theory.
1937, with the cooperation of two assistants, he deduced the equation of motion from the gravitational field equation of general relativity, further revealing the unity of time and space, matter and motion, which was a major development of general relativity and the last major achievement Einstein made in scientific creation activities.
He never succeeded in the same theory. He never gets discouraged and always starts from scratch with confidence. Because he was far away from the mainstream of physics research at that time, he went alone to overcome the problems that could not be solved at that time. So contrary to the situation in the 1920s, he was very isolated in physics in his later years. However, he is still fearless and unswervingly follows his own path. Until the day before his death, he was still in his hospital bed preparing to continue his mathematical calculation of the unified field theory.