The fact that the reflected light has half-wave loss proves that the reflected light is not simply reflected from the incident light by the medium interface directly, but has a deep physical mechanism and significance. According to my long-term research, the reflected light is actually a part of the secondary light generated after the incident light makes the atoms on the reflecting interface polarize into electric dipoles. This physical phenomenon reveals the law of interaction between light and medium: the atoms in the medium are converted into electric dipoles by incident photopoles and generate secondary light, and the incident light will be gradually cancelled out and disappear by secondary light in this process. Generally, the refracted light entering the transparent medium and the transmitted light passing through the transparent medium are part of the secondary light produced by the medium, not incident light or its variant.