The Elastic Medium Origin of Electromagnetic Waves A Unified Derivation of the Transverse Displacement Field, Maxwell's Equations, and the Masslessness of the Photon

This paper proves that the "mutual generation" of electric and magnetic fields in Maxwell's equations is a mathematical projection rather than physical causality. In the nonlinear elastic medium framework, the transverse shear displacement field uT is the sole physical entity — the electric field E is proportional to its time derivative and the magnetic field B to its spatial curl, making them two orthogonal algebraic components of the same transverse wave. No physical process of "changing electric field producing magnetic field" exists — E and B coexist, neither generating the other. This clarifies a long-standing conceptual ambiguity in classical electrodynamics.