He believes that "light is the longitudinal wave of ether", and the color of light is related to its frequency. How can light be waves? British physicist Newton said that this is obviously a particle. 1666, Newton took a vacation at home to avoid the Black Death, so he fiddled with the prism. He found that a beam of white light can be divided into different colors, and different monochromatic lights can also be synthesized and reduced to white light. To this end, he successfully explained the dispersion phenomenon of light. (See [Boiling Physics] (12): Good "color" person) Newton's spectroscopic experiment made optics leap from geometric optics to physical optics. Newton thought that light should be composed of particles and take the fastest straight path. The decomposition and synthesis of light is the result of the separation and mixing of particles of different colors.