What is the relationship between history, quantum theory and classical mechanics?

Quantum mechanics is a branch of physics that studies the laws of motion of microscopic particles. It mainly studies the basic theory of the structure and properties of atoms, molecules, condensed matter, nuclei and elementary particles. Together with the theory of relativity, it forms 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. Quantum mechanics is a physical theory that describes microscopic matter. Together with the theory of relativity, it is considered as the two basic pillars of modern physics. Many physical theories and sciences, such as atomic physics, solid state physics, nuclear physics, particle physics and other related disciplines, are based on quantum mechanics. Theoretical mechanics mainly studies the mechanical properties and operating rules of rigid bodies. It is the basic discipline of mechanics, which consists of statics, kinematics and dynamics.