关于光的本性和传播等问题，在很早就引起人们的注意。古希腊的哲学家们提出

Questions about the nature and spread of light have drawn people's attention very early. Ancient Greek philosophers put forward the following views: the sun and all other objects that emit light and heat emit tiny particles that can cause people to feel light and heat. In the seventeenth century, there were two questions about the nature of light Different doctrines. One school is the particle theory of light advocated by Newton, which believes that light is a particle emitted from a luminous body and propagating into space at a certain speed. Another group is the theory of light fluctuations proposed by Huygens, who believes that light is a kind of fluctuation propagating in the medium. Both the particle theory and the wave theory can explain the reflection and refraction of light. However, when explaining the refraction phenomenon of light entering the water from air, the particle theory concludes that the speed of light in water is greater than the speed of light in the air, and the wave theory concludes that water The speed of light is less than the speed of light in the air. At that time, people could not accurately measure the speed of light by experimental methods, so it was impossible to judge the merits of these two theories based on the phenomenon of refraction. From the end of the nineteenth century, in order to explain a series of newly discovered phenomena (such as the photoelectric effect, etc.), it must be assumed that light is a stream of particles formed by particles with a certain mass, energy, and momentum. Such particles are called photons. The above assumption was made by Einstein in 1905 and is called the photon hypothesis. The coexistence of the two aspects of light fluctuations and particles is called the duality of light. In the 1930s, people discovered the duality of real and physical particles. The duality of waves and particles is the basis of modern physics.

The nature and spread of light have attracted people's attention very early. The ancient Greek philosophers put forward the idea that the sun and all other light and heating objects emit tiny particles that evoke the feeling of light and heat, and in the seventeenth century there were two different theories about the nature of light. One is the particle of light that Newton claims, a particle that is thought to be emitted from a light-emitting body and travels toward space at a certain speed. The other is the wave of light advocated by Huygens, which considers light to be a fluctuation in the media. Particles can explain the reflection and refraction of light, but in explaining the refractive phenomenon of light entering the water from air, the particle says that the speed of light in the water is greater than the speed of light in the air, while the the conclusion of the fluctuating is that the speed of light in the water is less than the speed of light in the air. At that time, people could not accurately use experimental methods to determine the speed of light, so it was not possible to judge the merits of these two theories according to the refractive phenomenon. Beginning at the end of the nineteenth century, in order to explain a series of newly discovered phenomena (such as the photoelectric effect, etc.), it is necessary to assume that light is a stream of particles thicked by particles with a certain mass, energy, and momentum, called photons. The above assumptions were made by Einstein in 1905, known as the photon hypothesis. The coexistence of light and particles is called the diphonability of light. In the 1930s, the second-like nature of real and physical particles was discovered. The duality of waves and particles is the basis of modern physics.

People have been paying attention to the nature and propagation of light for a long time. Ancient Greek philosophers put forward the following view: the sun and all other luminous and hot objects emit tiny particles, which can cause people's feeling of light and heat. In the 17th century, there were two different theories about the nature of light. One is the theory of light particles advocated by Newton, which holds that light is a kind of particle emitted from a luminescent body and propagated to space at a certain speed. The other is Huygens's theory of light wave, which considers light as a wave propagating in the medium. Both particle theory and wave theory can explain the reflection and refraction of light. However, when explaining the refraction of light from air into water, the conclusion of particle theory is that the speed of light in water is faster than that in air, while the conclusion of wave theory is that the speed of light in water is slower than that in air. At that time, people could not accurately measure the speed of light with experimental methods, so they could not judge the merits of the two theories according to the refraction phenomenon. Since the end of the 19th century, in order to explain a series of newly discovered phenomena (such as photoelectric effect), it is necessary to assume that light is a stream of particles with certain mass, energy and momentum, which are called photons. The above hypothesis was put forward by Einstein in 1905, which is called photon hypothesis. The coexistence of light waves and particles is called light duality. In the 1930s, the duality of real and matter particles was discovered. The duality of wave and particle is the basis of modern physics.<br>