1. Mathematics
Mathematics can be divided into pure mathematics and applied mathematics. Pure mathematics mainly studies the structure and properties of mathematics itself, including algebra, geometry, number theory and so on. Applied mathematics is the application of mathematical theory to practical problems, such as cybernetics, operational research, statistics and so on.
Mathematics is a general means for human beings to strictly describe the abstract structure and mode of things, and all mathematical objects are artificially defined in essence. In this sense, mathematics belongs to formal science, not natural science.
2. Physics
Physics is a subject that studies the basic laws and essence of natural phenomena. It can be divided into classical physics and modern physics, in which classical physics includes mechanics, heat, electromagnetism and optics, and modern physics includes relativity, quantum mechanics and cosmology.
The actual physical phenomena and laws are generally complex and involve many factors. Discard the secondary factors and grasp the main factors, thus highlighting the essential characteristics of objective things, which is called establishing a physical model. The essence of physics is to establish a physical model for the research object, study the model through mathematical tools, and then explain and predict the research object.
3. Chemistry
Chemistry is a science that studies the composition, properties, structure and changing laws of matter. Chemistry can be divided into inorganic chemistry, organic chemistry, physical chemistry and other professional fields.
4. Astronomy
Astronomy is a science that studies astrophysics and the laws of shape, structure and motion of celestial bodies. It can be divided into celestial mechanics, cosmic physics, astrochemistry, astrometry and other professional fields.
5. Earth science
Earth science is a science that studies the physical, chemical and biological characteristics of the earth and its various levels. It includes geophysics, geology, geochemistry and so on.
6. Life sciences
Life science is the study of life and its structure, function, development and evolution, including biology, biochemistry, ecology, genetics and other professional fields.
These are the main fields of science, and they are also the courses of most high schools. There are many sub-disciplines and cross-disciplines in this field, such as statistical physics, biomedical engineering, environmental chemistry and so on.