What is quantum mechanics? Who can explain the theory of quantum mechanics?

Planck-Einstein's light quantum theory is the first breakthrough on the problem of blackbody radiation. Planck put forward the concept of quantum -h in order to deduce his formula theoretically, but it did not attract many people's attention at that time. Einstein put forward the concept of light quantum by using quantum hypothesis, thus solving the problem of photoelectric effect. Einstein further applied the concept of energy discontinuity to the vibration of atoms in solids, and successfully solved the phenomenon that the specific heat of solids tends to zero at T→0K. The concept of light quantum has been directly verified in Compton scattering experiment. Bohr's quantum theory Bohr creatively solved the problems of atomic structure and atomic spectrum with the concept of Planck-Einstein and put forward his atomic quantum theory. It mainly includes two aspects: a. Atomic energy can only exist stably in a series of states corresponding to discrete energy. These states become stable. When an atom transitions between two steady states, the frequency v of absorption or emission is unique and given by hv=En-Em. Bohr's theory achieved great success, which opened the door for people to understand the atomic structure for the first time, and its existing problems and limitations were gradually discovered by people. De Broglie's matter wave is inspired by Planck and Einstein's light quantum theory and Bohr's atomic quantum theory. Considering that light has wave-particle duality, it is assumed that real physicists also have wave-particle duality according to the analogy principle. He put forward this hypothesis, on the one hand, in an attempt to unify physical particles with light, on the other hand, in order to understand the discontinuity of energy more naturally, thus overcoming the shortcomings of Bohr's artificial quantization conditions. In the electron diffraction experiment of 1927, the direct proof of physical particle fluctuation is realized. The establishment of quantum mechanics Quantum mechanics itself was established in the period of 1923- 1927. Almost at the same time, two equivalent theories-matrix mechanics and wave mechanics were put forward. The introduction of matrix mechanics is closely related to Bohr's early quantum theory. On the one hand, Heisenberg inherited the reasonable concepts in early quantum theory, such as energy quantization, steady state and transition, and abandoned some concepts without experimental basis, such as electron orbit. The matrix mechanics of Heisenberg, Born and Jordan can be measured physically, and each physical quantity is given a matrix. Their algebraic operation rules are different from classical physical quantities and obey algebra which is not easy to multiply. Wave mechanics comes from the idea of matter waves. Inspired by matter wave, Schrodinger discovered a motion equation of matter wave in quantum system-Schrodinger equation, which is the core of wave mechanics. Later, Schrodinger also proved that matrix mechanics and wave mechanics are completely equivalent and are two different forms of the same mechanical law. In fact, quantum theory can be expressed more generally, which is the work of Dirac and Jordan. The establishment of quantum physics is the result of the joint efforts of many physicists, which marks the first successful supplement of physics research. Quantum mechanics is a branch of physics that studies the laws of motion of microscopic particles. The basic theory mainly studies the structure and properties of atoms, molecules, condensed matter, nuclei and elementary particles, which together with the theory of relativity constitutes the theoretical basis of modern physics. Quantum mechanics is not only one of the basic theories of modern physics, but also widely used in chemistry and many modern technologies. Some people cite randomness in quantum mechanics to support the theory of free will, but first, there is still an insurmountable distance between this randomness on the micro scale and macro free will in the usual sense; Secondly, it is difficult to prove whether this randomness is irreducible, because people's observation ability on the micro scale is still limited. Whether nature is really random is still an open question. Planck's constant is the decisive factor of this gap. Many examples of random events in statistics are strictly decisive. Supplement: This is a quantum diagram.