Aiming at the problems of traditional optical theories, such as the vague physical picture of the abrupt interface model, the half-wave loss relying on artificial boundary conditions, and the lack of intuitive explanation for the evanescent wave mechanism, this paper proposes a unified microscopic mechanism hypothesis for light interface effects based on the longitudinal-transverse composite wave aether model. The hypothesis holds that the aether density presents a continuous gradient distribution in space. On the atomic scale, there exists a radial density gradient around the atomic nucleus, forming a high-density "energy layer". On the macroscopic scale, the aether inside the medium has a uniform average density, which determines the overall refractive index. The surface of the medium is not an abrupt interface, but a transition layer with continuously changing density. Inside a uniform medium, the periodic arrangement of atoms leads to destructive interference of scattered wavelets, which macroscopically manifests as transparency and reduced light speed. At the interface, the discontinuity of atomic arrangement makes the backward scattering unable to cancel out, and the superposition forms macroscopic reflected light. Based on this microscopic picture, this paper systematically explains the phenomena of reflection, refraction, total internal reflection, evanescent wave and half-wave loss at both light-sparse to light-dense and light-dense to light-sparse interfaces. All effects are naturally derived from the interaction between aether density gradient and photons, without additional assumptions of boundary conditions. This paper also presents testable inferences and verification ideas of the model, providing a self-consistent classical fluid dynamic interpretation framework for interface optical phenomena.
Jingyuan Guo (Fri,) studied this question.