Reconstruction of Galactic Dynamics Based on the Mutual Gravitational Mechanism of Galactic Stars(Revised Edition)

Current research in galactic dynamics commonly adopts the singlecenter gravitational model developed for the solar system, which is welljustified and highly accurate within the solar system. This paper shows through comparative analysis that the validity of the solarsystem model arises from the highly concentrated central mass: the Sun accounts for 99.86% of the total mass of the solar system, so the singlecenter approximation reliably describes planetary motion. In the Milky Way and spiral galaxies, however, matter is diffusely distributed, and the central mass fraction is far too low to justify the singlecenter approximation. Directly extending the solarsystem model to galactic scales—while ignoring mutual gravitational interactions between stars, universal gravitational superposition, and chaindragging between adjacent stars—leads to systematic discrepancies between theoretical calculations and observations, and has indirectly motivated hypothetical concepts such as dark matter. Based on the fundamental law of universal gravitation, this paper presents a galactic dynamics model incorporating universal gravitational superposition and chaindragging. The model demonstrates that the motion of outer stars is dominated by gravity from nearby stars, with distant gravity playing only a secondary role; spiral arm structures in spiral galaxies arise naturally from nearby gravitational dragging; and the longterm stability and integrity of galaxies are maintained by chainlike constraints in which inner layers pull middle layers, and middle layers pull outer layers. The model can be implemented via numerical simulation, uses no unseen matter or free parameters, and relies only on visible matter and classical gravity to explain key observational features including flat rotation curves and stable spiral arms. It thus provides a physically consistent framework for galactic dynamics research.