Mainstream physics attributes gravity to the curvature of spacetime caused by mass, yet fails to explain why mass generates gravity. Based on the previously proposed framework of the conversion between matter energy and space energy, this paper argues that gravity is not an inherent property of mass, but a local space contraction effect caused by unsaturated microscopic particles absorbing space energy. During nuclear fission and radioactive decay, unsaturated particles released by radioactive elements (such as α particles, β particles, neutrons, etc.) are trapped inside celestial bodies and continuously absorb space energy, causing space to contract toward the center of the celestial body. This contraction effect is gravity. From the Earth to the Sun to black holes, the difference in gravitational strength stems from the total amount and degree of unsaturation of unsaturated particles. This framework can also naturally explain phenomena such as galactic rotation curves without introducing the hypothesis of dark matter. This paper provides a unified explanation for the gravitational origin of celestial bodies and proposes testable predictions.
Fuyuan Zhang (Thu,) studied this question.