People once had a great debate about the nature of light. Some people think light is a shear wave, while others think light is a particle. Now we know that light has wave-particle duality, but at that time, the two factions quarreled fiercely. Fresnel, a French engineer, published a paper in 18 18, discussing the viewpoint that light should be a shear wave. Mathematician Poisson said, you are joking. If light is really a shear wave as you say, then according to my calculation, if an opaque circular plate is placed on the propagation path of the light beam, a bright spot should appear in the center of the shadow of the circular plate at a certain distance from the circular plate because of the diffraction of light at the edge of the circular plate. Like light passing through a circular plate. Light will bypass obstacles. Have any of you ever seen this phenomenon? How anti-common sense, how ridiculous, it's sheer nonsense! Don't question my calculation process, I am a mathematician. This objection is so convincing and impeccable in mathematics that it can almost be sentenced to death for "light fluctuation theory". But according to Poisson's calculation, Fresnel did see this legendary bright spot in the experiment. Poisson not only harvested a swollen face, but also harvested a bright spot named after him, "Poisson Bright Spot".