Einstein made at least three great achievements: he put forward the light quantum hypothesis (photon theory), established the theory of relativity (special relativity and general relativity) and established the modern cosmology. Einstein's major achievement began in 1905, which was later called "Einstein's miracle year" by the scientific community: 1905. In March, Einstein applied Planck's energy quantum hypothesis and put forward the light quantum hypothesis (later called photon theory). In April, Einstein submitted a paper "A New Method for Determining Molecular Size" to the University of Zurich, and finally with strong arguments. In May, Einstein finished an epoch-making paper on electrodynamics of moving objects in modern physics, put forward the principle of special relativity independently and completely, established the special relativity, and initiated a new era of physics. In June, Einstein put forward the light quantum hypothesis in "An Inspiring Viewpoint on the Generation and Transformation of Light" (and "On the Generation and Absorption of Light" in March of 1906), established the photon theory, and re-emphasized the particle nature of light; In September of the same year, Einstein wrote in his paper "Is the inertia of an object related to the energy it contains? A primitive form of the relationship between mass and energy was put forward in "",which became the most famous formula in special relativity after rewriting: mass-energy equation (E = MC 2); 1906, Einstein finished the paper on the specific heat of solid based on Planck radiation and specific heat theory, and created the first model of quantum theory of specific heat of solid: Einstein model; 1907, Einstein put forward the principle of equivalence and took the first step to establish the general theory of relativity. 19 13, Ains further elaborated the principle of general relativity; 1915165438+1On October 25th, Einstein successfully established the gravitational field equation of general relativity (the famous mathematician Hilbert deduced the field equation mathematically five days earlier than Einstein, so the field equation is sometimes called Hilbert-Einstein gravitational field equation), and completed the theoretical establishment of general relativity; 19 16 is another year in which Einstein made great achievements. In March, Einstein completed a conclusive paper on the basis of general relativity, and the system of general relativity was completely established. In May, Einstein put forward the hypothesis that the universe is finite and unbounded. In August, Einstein completed the quantum theory of radiation, summarized the development of quantum theory and put forward the theory of stimulated radiation, which became the theoretical basis of laser technology. In the same year, Einstein further pointed out that photons also have momentum (the discovery of Compton effect in 1927 completely confirmed Einstein's light quantum hypothesis); 19 17, Einstein applied his general theory of relativity to study the whole universe and established the first self-consistent model of the universe (in order to keep the universe still, Einstein added a "cosmological constant" to his gravitational field equation to keep the model stable. 1929, Hubble discovered that the universe is not static, but has been expanding, which Einstein later called "the universe". 192 1 year, Einstein won the nobel prize in physics for his research achievements in photoelectric effect (not relativity, but widely recognized and highly praised after the end of world war ii); 1922, Einstein finished his first paper on the unified field theory, and started the research on the unified field theory (he tried to unify the electromagnetic field and the gravitational field, but failed); 1927, Einstein attended the 5th Solvay Physics Seminar in Brussels, and started a heated debate with Copenhagen School on the interpretation of quantum mechanics, and published Newtonian Mechanics and Its Influence on the Development of Theoretical Physics. From then on, it parted ways with the orthodox theory of quantum mechanics, which had a far-reaching impact on the development of quantum mechanics later (Einstein argued with Bohr about the completeness of quantum mechanics and put forward the famous "photon box" ideal. 1934, Einstein, Podolski and Rosen jointly published a paper challenging the Copenhagen school, putting forward the famous "ERP paradox" and questioning the incompleteness of quantum mechanics. 1937, Einstein cooperated with infeld and Hoffman to complete the paper "gravity equation and motion problem", and deduced the motion equation of matter from the field equation of general relativity, further revealing the profound internal relationship between time and space, matter and motion, which was Einstein's last major achievement; In addition to the above achievements, Einstein also made some other research achievements, and at the same time devoted himself to promoting the cause of human peace and popular science propaganda. All these achievements and efforts have greatly promoted the development of science and technology and the progress of human society, so Einstein became the greatest physicist in the 20th century.