Paper III Geometric Origin of Electromagnetic Forces-From Radial Twist to Maxwell's Equations

This paper is the third installment of the Planck Cube Space Theory series. Based on the discrete cubic lattice axioms (Paper I) and the geometric origin of electric charge (Paper II), it establishes a unified geometric framework for electromagnetic phenomena. The magnetic field is defined as the axial twist of Planck cubes; electric and magnetic fields are mutually converted through elastic coupling between radial and axial twists. Maxwell’s equations emerge naturally as the macroscopic manifestation of the dynamic equilibrium and wave propagation of twist fields in the cubic space. The microscopic mechanisms of the Lorentz force, Ampère force, and electromagnetic induction are given geometric interpretations. The lock-displacement-replacement model is proposed to explain the physical origin of motional electromotive force. Several testable predictions are presented, including current saturation in ultra-strong magnetic fields, excess current noise, and material-dependent systematic differences. The core conclusion of this paper is rigorous: all electromagnetic forces arise from the tendency of twisted space cubes to restore equilibrium. The detailed microscopic kinetic models presented are preliminary geometric illustrations and may be further refined in subsequent works, without affecting the validity of the core framework and axiomatic system.