Free high-energy gamma photons possess no rest mass, fixed volume or electric charge, and only carry light energy while propagating at the speed of light. All stable macroscopic matter in the universe consists of protons, electrons and neutrons. Based on the strong self-locking bound closed-loop spin model, this paper clarifies that rest mass, volume and charge are not intrinsic properties of gamma photons. Instead, they are external manifestations exhibited by the whole cluster when high-energy gamma photons are confined in microscopic space via strong self-locking and maintain closed-loop spin. The intrinsic state of gamma photons inside the self-locked structure remains unchanged, always without mass or electric charge. The universally recognized mass-energy conversion law supports the logic for the formation of rest mass, and the physical property origins of the three fundamental particles are analyzed uniformly. A brief discussion is given on the reversible flipping of neutrons and antineutrons as the core condition for the persistence of the material world. Hard evidence including nuclear explosions, black hole jets and electron-positron annihilation experiments is supplemented for verification. Constructed based on universally accepted physical laws, the model adopts strong self-locking to interpret the stable confinement mechanism of particles, contains no hypothetical particles, and features a self-consistent logical system.
Jiaqing Yan (Sat,) studied this question.