A Study on Light Propagation and Gravitational Optical Effects under the Qi Medium Model

The scientific value and theoretical rationality of general relativity are unquestionable. The theory has been verified by numerous astronomical observations and experiments, and has achieved universally recognized success in quantitatively predicting gravitational optical and celestial mechanical effects. However, existing physical theories are not the ultimate truth of the universe. Without revealing the essential cosmic laws, multiple logically self-consistent theoretical interpretations that agree with measured data can coexist for the same astronomical phenomenon. This paper abandons the geometric interpretation of spacetime curvature. Based on the cosmic fluid framework of the Qi medium, which assumes that cosmic space is filled with a uniform continuous medium with fundamental fluid properties, we establish the coupling relation between radial density distribution and refractive index of a spherically symmetric Qi medium. Model parameters are calibrated independently using the perihelion precession data of Mercury. Then the gravitational light deflection angle of the Crab Nebula pulsar is calculated quantitatively. The results show that the deflection angle predicted by the Qi medium model is 0.319'', which falls exactly within the measured range 0.31''$--$0.33'', and agrees well with the prediction of general relativity. This work does not contradict general relativity, but provides an equivalent theoretical framework from a new medium perspective. It confirms that gravitational optical phenomena can be explained reasonably by different physical mechanisms, and offers new thoughts and quantitative support for diversified interpretation of gravitational effects. Keywords: Qi medium model; gravitational optics; light deflection; Mercury precession; diversified theoretical interpretation