What is the relationship between quantum mechanics and classical mechanics?

Quantum mechanics. and classical mechanics are the two cornerstones of physics as we know it today。Classical mechanics describes the behavior of macroscopic objects, which have a relatively small velocity compared to the speed of light.

Quantum mechanics describes the behavior of microscopic objects, such as subatomic particles, atoms, and other small objects. These two are the most important areas in physics. Having a proper understanding of these areas is now important in all parts of physics.

Classical mechanics is the study of macroscopic objects. The motion and statics of macroscopic objects are discussed under classical mechanics. There are three distinct branches of classical mechanicsNamelyNewtonian mechanics, Lagrangian mechanics, and Hamiltonian mechanics

These three branches are mathematical methods used to study motion. For example, Newtonian mechanics uses displacement, velocity, and acceleration.

Isovectors are used to study the motion of an object, whereas Lagrangian mechanics uses the energy equation and the rate of change of energy to study. Choose the appropriate method based on the problem you want to solve. Classical mechanics is applied in places such as planetary motion, projectiles, and most events in everyday life.

In classical mechanics, energy is seen as a continuous quantity.

Quantum mechanics is the study of microscopic objects. The term "quantum" stems from the discovery that the energy of microscopic systems is quantized. Photon theory is one of the cornerstones of quantum mechanics.

It states that the energy of light is in the form of wave packets. Heisenberg, Max Planck, Albert Einstein.

are some of the leading scientists involved in the development of quantum mechanics.

Quantum mechanics is divided into two categories. The first is non-relativism.

Quantum mechanics of objects, a field that studies the quantum mechanics of particles with relatively small velocities compared to the speed of light. Another form is relativistic quantum mechanics, which studies particles moving at speeds compatible with the speed of light. It is worth mentioning Heisenberg's uncertainty principle.

It is also a very important theory behind quantum mechanics.

Quantum mechanics applies to microscopic objects, whereas classical mechanics applies only to macroscopic objects.

Quantum mechanics can be applied to macroscopic objects, but classical mechanics cannot be applied to microscopic systems.

Classical mechanics can be seen as a special case of quantum mechanics.

Classical mechanics is a fully developed field, whereas quantum mechanics is still a developing field.

In classical mechanics, most quantum effects, such as the quantization of energy, the uncertainty principle, are useless.

In addition,The ** of quantum mechanics has been experimentally checked to an extremely high levelAccuracyis one of the most accurate theories in the field of science. According to the correspondence principle, if a quantum system has reached a certain "classical limit", its physical behavior can be described very accurately by classical theory. This classical limit can be a large number of subs.

limit, which can also be Planck's constant.

Towards the zero limit. <>

Summary

In summary, quantum mechanics describes macroscopic objects, while classical mechanics is more applicable to large objects. However, there are many similarities between quantum mechanics and classical mechanics when it comes to depicting large objects.

Both are very important physics, and quantum mechanics is based on classical mechanics, but there are more detailed descriptions of the mechanics of the microscopic world, and the two do not necessarily fit.

Classical mechanics describes the laws of motion of macroscopic forms of matter, while quantum mechanics describes the laws of motion of microscopic forms of matter.

Quantum mechanics is the mechanics of absolute motion change, while classical mechanics is the mechanics of rest and motion, and it is the mechanics of movement only after God kicks it. Quantum mechanics has the principle of uncertainty and uncertainty. Classical mechanics does not.

In Newton's time, classical mechanics was the theory of understanding the world and driving the course of the Industrial Revolution; After two centuries of development, people found that classical mechanics could not explain some problems, and then at the beginning of the 20th century, the theory of relativity and quantum mechanics were born, which promoted the world to develop faster. Let's discuss the connection between classical mechanics and quantum mechanics.

There is a saying that the connection between classical mechanics and quantum mechanics is not very large, and if you learn classical mechanics, you will be troubled by some concepts when you learn quantum mechanics, and there is a lot of truth in this statement. However, the students of the Department of Physics first study classical mechanics and then quantum mechanics, and they must not forget about classical mechanics and then learn quantum mechanics. In fact, according to the order of the development of things, then things also have their inevitable connections, let's look at some of the connections between them.

In classical mechanics, the law of motion of things is understood from the point of view of force, and when we accept Newton's three laws, we can measure the physical motion in space. Once we know the momentum and displacement of the particles, we can obtain arbitrary physical quantities.

Then there are also five basic assumptions in quantum mechanics, which many people consider incredible. This is normal, because these hypotheses of quantum mechanics are indeed somewhat controversial, but they are also the result of a large number of experimental observations. Therefore, to learn quantum mechanics, we must first accept these assumptions, which are the starting point of the entire quantum system.

The reason why we feel that the assumptions of classical mechanics are understandable and the assumptions of quantum mechanics are not conducive to understanding is that we live in a macroscopic world, and most of the laws of the macrocosm are truly visible and meet the requirements of classical mechanics, and can be really felt, but it is almost difficult to find the laws of quantum mechanics in the macroscopic world, so there will be problems in cognition. Therefore, when learning quantum mechanics, we first accept the basic assumptions of quantum mechanics, and after a period of time, we will naturally accept them.

With the basic assumptions in mind, let's move on to the next part.

The bridge between quantum mechanics and classical mechanics is the Poisson's bracket (p-to-to-eon), which satisfies [x,y]=ih; At the same time, with the help of the concept of Hamiltonian in theoretical mechanics, all the mechanical quantities in the Hamiltonian are replaced with mechanical quantity operators to obtain the required equations. Therefore, a deep understanding of the Hamiltonian in theoretical mechanics will be of great help to quantum mechanics.

Finally, to sum up, both classical mechanics and quantum mechanics are intended to explain the laws of the macroscopic or microscopic world, but they are different in the way they describe the system and have different equations of motion. As long as everyone calms down to experience quantum mechanics and puts quantum mechanics on the altar, they will definitely successfully pass the quantum mechanics in the postgraduate entrance examination.

What is Quantum Mechanics? Why is it said that if you master quantum mechanics, you have the ability to change the world.

Quantum mechanics is the basic theory for understanding physical phenomena at the subatomic scale. It was developed in the early 20th century and was based on the results of some special experiments and new ways of thinking. Just as classical physics describes the laws of macroscopic objects, quantum mechanics describes the laws of microscopic particles (e.g., electrons, protons, neutrons, etc.), which plays a very important role in our understanding of the microscopic world of nature.

Quantum mechanics has many wonderful concepts and laws. The most well-known of these is wave-particle duality and the uncertainty principle. According to wave-particle duality, these microscopic particles can either evolve like waves, or they can have properties such as position and momentum like particles.

At the microscopic level, the state of motion of particles cannot be completely **, and this chaotic state is uncertainty. The uncertainty is related to the fact that the results of the observation operation inevitably interfere with the original state of the system.

In addition, transient phenomena, discrete phenomena, matrix mechanics, and relativistic quantum mechanics are the core theories of quantum mechanics, which provide effective methods for us to deal with various complex situations.

Quantum mechanics has a wide range of applications in a variety of fields, including atomic physics, chemistry, semiconductor electronics, quantum computers, and quantum communications. Among them, the application of semiconductor physics is the most significant. In the field of nanoelectronics, as the size of modern electronic devices has been reduced to the same order of magnitude as microscopic particles, accurate calculations have become a necessary technology instead of traditional wind measurement.

With the rapid development of quantum mechanics, more and more researchers are committed to exploring its deeper nature and applications. The establishment of a new quantum communication network and the construction of a practical "hardware quantum computer" in the true sense of the word have all promoted the prosperity and progress of the field of quantum mechanics. At the same time, there are also areas such as the problem of information loss in black holes, "faster-than-light" transmission events, etc., these unsolved scientific questions lead us to think about the possible new laws of physics.

To sum up, quantum mechanics is a basic branch of physics that studies the state of motion of microscopic particles and their essential laws. Among the various novel and bizarre phenomena, quantum mechanics has given mankind a new understanding of the microscopic world and helped us explore the mysteries of the natural world. The efforts of modern scholars in theoretical exploration and practical applications will continue to advance the development of science and technology, creating new fields that will make important contributions to human life.

The differences between classical physics and quantum physics are as follows:

1. Classical physics deals with the motion of particles and the fluctuation of particle swarms or fields almost independently, but quantum mechanics must deal with particles and waves in a unified manner.

2. In physics, classical physics is ideally used when ignoring quantum, but quantum physics is required for the study of microscopic phenomena rigorously;

3. Classical physics in macroscopic, low-velocity and weak-field situations.