This paper analyzes a fundamental geometric oversight in the classical interpretation of the Michelson -Morley experiment. We demonstrate that in a frame moving with velocity u , the reflection of light from a mirror follows a specific angular deviation. By introducing the formula sinu2061〖β=u/c〗 √(1-u^2/c^2 ), we prove the optical paths are asymmetrical. This geometric shift provides a new basis for understanding the "null result" of the Michelson-Morley experiment without necessitating postulate of absolute constancy of light in all frames. In other words, the Michelson-Morley experiment is a failed experiment and the physical-mathematical conclusions drawn from its "results" have no scientific basis.The question of the nature of light is directly related to the Michelson-Morley experiment. Since the aforementioned experiment can be considered a failure, the idea of the ether becomes relevant. For this reason, a new idea is proposed to solve the problem of light propagation. Light is attributed only a wave nature in the form of spherical waves, and the propagation medium is dark matter. The idea is substantiated by appropriate calculations. . The mass of a dark matter particle has also been determined, which is found to be equal to M_dm≈4.〖10〗^(-34) kg.Keywords: Light, Michelson-Morley, experiment, theory, law, ether, wave, dark matter.