In the development history of physics for hundreds of years, a large number of great scientists have emerged, and these scientists have put forward many classic theories, which have promoted the development of physics. In physics, there are four classical hypotheses corresponding to four classical theories. These four hypotheses are also called the four beasts. The four great beasts are Schrodinger's cat, Zhi Nuo's tortoise, Laplacian demon and Maxwell demon.

Among them, Schrodinger's cat corresponds to quantum mechanics, Zhi Nuo's tortoise corresponds to calculus, Laplacian demon corresponds to classical mechanics, and Maxwell demon corresponds to the second law of thermodynamics. As for why Laplace demon can be selected as one of the four great beasts, it is because it is a classical hypothesis based on classical Newtonian mechanics.

Laplace is a famous French mathematician. He is a believer in the theory of light particles. Its era is dominated by Newtonian mechanics, and all movements, whether in the sky or underground, can be explained by Newtonian mechanics. Some of his works are also based on classical mechanics. At that time, people's general understanding of the world was optimistic, and some even wrote poems? Nature and its laws are hidden in the darkness. God said that when Newton was released, everything became bright. ? So Laplace put forward a conjecture in 18 14: If the initial position and momentum of each particle in the system are known, the future state of particles can be calculated by classical mechanics. This creature that can calculate the future is called Laplacian.

In fact, does this omniscient and omnipotent creature really exist? Thirty years after Laplace's death, a scientist suggested that according to the second law of thermodynamics, if words were written on paper and burned, Laplace demon could not know the contents of words from ashes, because the process of entropy increase was irreversible. Then the Laplacian demon met quantum mechanics. Assuming that Laplace demon can calculate the future results, according to the point of view of quantum mechanics, this calculation will affect the future results, then Laplace demon needs to recalculate the affected future results, but this calculation will affect the future results, and so on, Laplace demon can't calculate the future at all. The most fundamental reason is that it is impossible to calculate the future results because of the uncertainty of electrons. From the above inference, we can know that the omnipotent Laplacian demon does not exist at all.