Physical theory is usually expressed in mathematical form. The laws of physics verified by a large number of rigorous experiments are called laws of physics.
Physics is a subject that studies the most general laws of material movement and the basic structure of material. Physics, as the leading discipline of natural science, studies the most basic motion forms and laws of all substances from the universe to elementary particles, so it has become the research basis of other natural science disciplines. Its theoretical structure takes mathematics as the working language and experiment as the only criterion to test the correctness of the theory. It is the most accurate natural science discipline today.
The field of physics research can be divided into the following four aspects:
1. condensed matter physics-study the macroscopic properties of matter. These stages contain a large number of components, and the interaction between team members is very strong. The most familiar condensed phases are solids and liquids, which are formed by bonds between atoms and electromagnetic forces. More condensed matter phases include superfluid and Bose-Einstein condensed matter (found in some atomic systems with very low temperatures); Superconducting phases of conducting electrons in some materials: ferromagnetic and antiferromagnetic phases in atomic lattice. Condensed matter physics has always been the biggest research field. Historically, it originated from solid state physics. 1967 was first put forward by philip anderson and adopted this name.
2. Atomic, molecular and optical physics-the study of substance-substance and light-substance interactions within the scope of atomic size or several atomic structures. These three areas are closely related. Because they use similar methods and related energy levels. They all include classical and quantum processing methods; Deal with problems from a micro perspective. Atomic physics studies the shell of atoms, focusing on the quantum control of atoms and ions; Cooling and trapping; Low temperature collision dynamics: accurate measurement of basic constants; Collective effect of electrons in structural dynamics. Atomic physics is influenced by the nucleus. However, nuclear phenomena such as nuclear division and nuclear synthesis belong to high-energy physics. Molecular physics focuses on polyatomic structure and its interaction with matter and light. Optical physics here only studies the basic characteristics of light and the interaction between light and matter in the microscopic field.
3. High energy/particle physics-particle physics studies the basic components of matter and energy and their interactions; Also known as high energy physics. Because many elementary particles do not exist in nature, they only appear when they collide with other particles in a high-energy particle accelerator. According to the interaction standard model of elementary particles, there are 12 elementary particle models of known substances (quarks and light particles). They interact through strong, weak and electromagnetic basic forces. The standard model also predicts the existence of the Higgs boson. Looking for it.
4. Astrophysics-Astrophysics and astronomy are physical theories and methods used to study the structure and evolution of stars, the origin of the solar system and related problems of the universe. Because astrophysics covers a wide range. It uses many physical principles. Including mechanics, electromagnetism, statistical mechanics, thermodynamics and quantum mechanics. 193 1 year, Karl discovered the radio signals from celestial bodies. Started radio astronomy. Space exploration has expanded the field of astronomy. The interference of the earth's atmosphere makes the observation space need infrared, ultra-ultraviolet, gamma rays and x-rays. Physical cosmology studies the formation and evolution of the universe on a large scale. Einstein's theory of relativity plays a central role in modern cosmic theory. At the beginning of the 20th century, Hubble discovered that the universe was expanding, which promoted the discussion of the steady-state theory of the universe and the Big Bang. 1964 The discovery of the cosmic microwave background proves that the Big Bang theory may be correct. The Big Bang model is based on two theoretical frameworks: Einstein's general theory of relativity and cosmological principles. Cosmology established ACDM universe evolution model; Including the expansion of the universe, black energy and black matter. Many possibilities and discoveries can be expected from the new data of Fermi gamma-ray telescope and the improvement of the existing universe model. Especially in the next few years, there may be many discoveries about dark matter.