A New Conception about the Origin of Gravitational Force_Version 4.0

Version 4.0. This manuscript constructs a cosmic framework based on vacuum fluid medium consisting of minimum positive and negative energy quanta, and explores the essential origin of gravitational interaction and cosmic spatial structure. The attached PDF and Word source documents are open for public access, and this research has not been submitted to any formal academic journals or released on other preprint platforms. Major revisions compared with Version 3 are listed below: 1. A complete mathematical derivation formula for density-dependent light speed is supplemented. The relational expression \(c\propto\sqrt{\rho}\) is deduced from the medium stiffness and inertial density formula, explaining the rule that light speed rises with the increase of vacuum fluid density around celestial bodies and declines in low-density cosmic regions. 2. The relevant discussion content of dark matter is completely deleted. The logarithmic correction term of gravitational potential generated naturally by vacuum medium is adopted to account for the binding effect on high-speed stars at galactic peripheries, which can perfectly prevent peripheral stellar escape without introducing the dark matter hypothesis. The uploaded documents correspond to the full revised manuscript of Version 4 for permanent open archiving.