What is wave-particle duality?

Wave-particle duality means that all particles or quanta can be described not only by particle terms but also by wave terms. This means that the classical concepts of "particle" and "wave" have lost the ability to completely describe the physical behavior in the quantum range.

Wave-particle duality is one of the basic properties of microscopic particles. 1905, Einstein put forward the optical quantum explanation of photoelectric effect, and people began to realize that light waves have both the properties of waves and particles.

Interference and diffraction of light indisputably show that bright light has fluctuation, while photoelectric effect indisputably shows that bright light has particle. For the macro world, fluctuations and particles are contradictory, and no macro object has both characteristics at the same time.

The fluctuation and particle nature of light are unified, but the nature of one aspect is more prominent in different situations.

Generally speaking, the effect produced by a large number of photons often appears as fluctuations, and the effect produced by a single photon often appears as particles. For example, in the interference experiment of light, if the incident light is weakened to the extent that photons can only pass through the slit one by one, the exposure time will be very short.

In this case, only some irregularly distributed light spots appear on the negative film, which are formed by photons hitting the negative film, showing the particle nature of light. If the exposure time is long enough and a large number of photons pass through the slit, regular interference fringes will appear on the negative film.

Bright stripes are areas where photons reach more, and dark stripes are areas where photons reach less. Interference fringes are seen in the experiment, which shows the fluctuation of light. Obviously, we can regard the fluctuation of light as the law of motion of a large number of photons.

Extended data

The essence of wave-particle duality

1. Observing light in time domain space by observing particles can obtain the particle nature of light. As Mr. Yangming said, it means filial piety, and filial piety is one thing. Similarly, it refers to the reality of electrons, and electrons are one thing. This means that light and photons are the same thing. It means the reality of neutrinos, which is one thing.

2. By observing light in frequency domain space by observing waves, we can get the fluctuation of light. In Young's double-slit interference experiment, the particle nature of light is used to describe the position of photons, and mathematical points can be used to describe the position of photons in frequency domain space, but mathematical points cannot represent photons themselves. The process of light interference fringes is also well explained.

In frequency domain space, a single electron will also form interference fringes. In an ideal state, interference fringes can also be obtained by replacing photons and electrons with bullets or stones in frequency domain space. It can be seen that it is unscientific to simply say that light fluctuates. This fluctuation of light stays in frequency domain space and is a probability wave.

3. In time domain space, light is embodied as particles; In frequency domain space, light is reflected as a probability wave. As Sun commented on stone, the essence of stone is hard and white. Kant said that we can't know things themselves, light things themselves, and stone things themselves.

In other words, without observation and senses, we can't fully understand light, even the stones we are used to. The so-called understanding is actually the process of creating phenomenal entities. When we observe light, we create photon phenomena in an instant. This is in line with what Mr. Yang Ming said about the unity of knowledge and action.

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