The Continuous Elastic Cosserat Medium: A Unified Field Theory of Matter, Forces, Spacetime, and Quantum Behavior (White Paper, v2: Single Postulate Formulation)

This white paper (version 2) presents a unified field theory based on a SINGLE postulate: the universe consists of a continuous elastic Cosserat medium. The key update from v1: The principle of least action is no longer an independent postulate. It is derived as Theorem 0 from the intrinsic property of an elastic medium — resistance to deformation and return to equilibrium. Thus, the entire theory now rests on one postulate. From this single postulate, we derive:- The finite speed of light and Lorentz symmetry as emergent properties of the medium's elastic ground state.- Quantum mechanics (wave-particle duality, Born rule, measurement collapse, uncertainty principle) as the effective dynamics of localized wave packets.- Protons and neutrons as topological solitons (B=1) of the orientational field.- Electrons as torsion bound states (hypothesis under investigation).- The four fundamental interactions (strong, electromagnetic, weak, gravitational) as distinct elastic responses of the same medium. The theory has exactly two free parameters (f_pi = 129 MeV, e = 5.4), fixed by the proton mass and charge radius. A 27-point experimental audit is presented. Three falsifiable predictions are identified: proton scalar polarizability, torsion-induced spin-spin force, and ultra-high-energy photon dispersion. This version includes: explicit derivation of least action from elasticity, full material properties of the medium (shear modulus, mass density, characteristic length), improved parameter convention clarity, honest labeling of hypotheses vs. theorems, and expanded open problems.