Young’s double slit experiments revived the wave theory of light. The standard interpretation is that the light behaves as waves before and after passing through the double slit, and the superposition of waves produces the interference pattern. Feynman called the double slit experiment the only mystery in quantum mechanics. In this article, we experimentally show the novel universal phenomena: (1) within macro-distance from the diaphragm, the light rays behave as photons and produce non-interference patterns; while near the screen, the photons produce interference patterns; (2) The non-interference patterns evolve to the interference patterns gradually in the same classical wave experiment; (3) the light is photons before and after passing through the double slit; (4) The convex lens stops the further evolution. The experiments: (1) challenge the wave theories of the light; (2) violate both Bohr’s complementarity principle and wave particle duality; (3) provide profound phenomena for developing optics and for studying the nature of light; (4) suggest that a complete theory should be able to consistently interpret all phenomena, including the non-interference pattern, the interference pattern, and the evolution from the non-interference to the interference pattern in the wave experiment; (5) show a new mystery that photons, as particles, distribute as waves.

double slit, cross double slit, grating, interference pattern, non-interference pattern, evolution of pattern, superposition of waves, wave particle duality