Quantum field is a theoretical generalization of classical field. We know that there are two typical classical fields: Maxwell electromagnetic field and Einstein gravitational field. One way to think about the quantization process is that we first reconstruct the (still classical) field equation on the basis of replacing some numerical values with mathematical operation symbols (this part is divided into pure algebra or calculus, and new physics has not been introduced); So, what about us Solve? The operator-valued equations obtained, including solutions that do not appear in classical theory, are then solved by these new? Meaningless? This solution accurately describes nature, including all observed quantum behaviors that contradict the classical theory.

There are several basic principles for using quantum fields. First, this is a natural generalization of many classical field theories, which are the most successful (non-quantum) theories we have studied on nature. Second, quantum field theory can explain the generation and destruction of particles and processes that do not exist in quantum mechanics. Third, quantum field theory is relativistic in nature. Magically? (Not true, just elegant mathematics) solved the problem of causality, which even puzzled the quantum particle theory of relativity.

However, quantum fields do not interact with matter. Quantum field is matter. In quantum field theory, we think that particles are excited by the quantum field itself.

The simplest? Practical? Quantum field theory is quantum electromagnetism. In quantum electromagnetism, two kinds of fields coexist: electromagnetic field and? Electronic field? . These two fields constantly interact, energy and momentum are transferred, and excitation is generated and destroyed. So, for example, the phenomenon that electrons absorb neutrons intuitively described by us is the concrete interaction between electromagnetic field and electron field in quantum electrodynamics. The electromagnetic field loses an excitation quantum and the electron field gains energy, momentum and angular momentum.

Lesson 65438: Field is the most basic substance. We learned in school that the basic component of matter is particles. In fact, we will continue to teach this in universities. We will explain in the university that quarks and electrons make up Lego bricks, and all substances are produced by such Lego bricks.

But this expression hides a profound truth. According to our most perfect laws of physics, the basic building blocks of nature are not completely separated particles. On the contrary, there is a continuous substance, which is distributed in the whole space like a liquid. We call these substances fields. The most familiar fields are electric and magnetic fields. The ripples of these fields produce light, or more generally, electromagnetic waves. The phenomenon that iron filings have a certain direction in the magnetic field is caused by bar magnets.

Lesson 2: Particles are produced by fields. If you are close enough to electromagnetic waves, you will find that they are made up of neutrons. When we include the action of quantum mechanics, the ripples of electric and magnetic fields will become particles.