The Grand Unified Theory of Light Origin: The Underlying Unified Mechanism of Cosmic Origin, Mass, Charge and Fundamental Forces

Based on the Grand Unified Theory of Light Origin, this paper proposes that photons are the sole primordial units constituting the universe, and constructs a complete physical system covering mass-energy generation, microscopic particle formation, hierarchical division of interaction forces and the evolution of macroscopic matter. It interprets the underlying physical mechanism of the absolute constancy of the speed of light, strictly distinguishes the intrinsic speed of photons from the relative speed observed in reference frames, and corrects long-standing misunderstandings of the speed of light in classical physics and modern relativity systems. It further reveals the structural generation mechanism of mass originating from bound photons and charge, the energy exchange principle of electron energy level transitions, and the underlying logic of mass-energy release in nuclear explosions. This paper defines that protons, neutrons and electrons are the only three fundamental physical particles in the universe, and demonstrates the irreplaceable core role of neutrons in the construction of atomic nuclei and the evolution of diverse matter. By classifying primary primordial fundamental forces and secondary derived interaction forces, a fully self-consistent logical closed loop covering the structures of microscopic particles, mass-energy conversion laws and the evolutionary systems of the macroscopic universe is realized.