And Poisson was a staunch supporter of the particle theory, and naturally sneered at Fresnel’s answer. Through calculations, he concluded that if Fresnel’s theory was correct, a phenomenon that was very challenging to conventional views would occur: if an opaque circular plate was placed in the path of a light beam, then due to light diffraction at the edge of the circular plate, a bright spot should appear at the center of the circular plate’s shadow, at a certain distance away. In plain language.... ahem, to simplify it: if you shine a flashlight on an opaque plate, a light spot will appear at the center of the shadow behind the plate. At the time, this was simply an impossible situation. Even now, it still seems a bit incredible. Young Fresnel himself hadn’t expected such a magical result from his theory, but he ultimately accepted the challenge. After careful experimentation, the moment for witnessing a miracle finally arrived: as the light shone through, a bright spot indeed appeared at the center of the circular plate’s shadow! And this bright spot thus became known as the "Poisson spot," and this event became one of the biggest face-slapping incidents in the history of science. As a staunch supporter of the particle theory of light, Poisson, at the most famous conference venue of the time, in front of countless peers, chose diffraction as the subject of an essay contest, also somewhat as a way to vindicate the old ancestor, Huygens. At that time, Fresnel had just transitioned from civil engineering to optics, already showing promise, and participated in this competition. Coincidentally, Fresnel had already considered this problem before the competition, believing that light is a wave with diffraction phenomena. Taking advantage of this occasion, he submitted his paper early to await the decision of the expert review committee. The chief expert of this review committee was the renowned Poisson.