Current studies in galactic dynamics generally adopt the single-center gravity model from the solar system, which is fully reasonable and highly accurate within the solar system. Through comparative analysis, this paper points out that the validity of the solar system model is based on the highly concentrated central mass: the Sun accounts for 99.86% of the total mass of the solar system, so the single-center approximation well describes the motion of planets. In the Milky Way and spiral galaxies, however, matter distribution is obviously diffuse, and the central mass ratio is far from sufficient to support the single-center gravity approximation. Directly extending the solar system model to galactic scales—ignoring the mutual gravity between stars, the global superposition effect, and the chain drag effect between adjacent stars—leads to systematic deviations between theoretical calculations and observations, and indirectly spawns theoretical hypotheses such as dark matter. Based on the fundamental law of universal gravitation, this paper proposes a galactic dynamics model considering the global gravitational superposition and chain interactions of stars, and provides a modeling approach realizable via computer numerical simulation, aiming to offer a more realistic physical framework for galactic dynamics research.
Jiaqing Yan (Mon,) studied this question.