Dual-Layer Light v3.0: From Light Speed Invariance to the Existence of Ma — A Deductive Approach

This paper reverses the direction of reasoning in the Dual-Layer Light framework. Rather than proposing Ma (間) as a hypothesis and deriving c invariance as a consequence (v1.0, v2.0), this version begins from c invariance as an established experimental fact and asks: what structural conditions does it logically require? Three qualitative distinctions establish that c is categorically different from other physical constants: (1) c is a boundary condition of spacetime structure, not a measurable quantity within it — c defines the metric ds² = c²dt² - dx²; (2) c is observer-independent across all inertial frames, not frame-local like relativistic mass; (3) c defines the propagation speed of causality itself, not a specific interaction. From these three distinctions, a logical requirement is derived: c invariance requires a perfectly uniform substrate that is universal, structurally prior to spacetime, and information-carrying. This substrate is identified with Ma (間) — the cosmic information density field φ₂ [J/m³] in its ground state of uniform distribution. The deductive chain: c invariance (fact) → c is a spacetime boundary condition (relativity) → invariant boundary condition requires uniform substrate (logic) → substrate is universal, prior, information-carrying (from three distinctions) → substrate = Ma = φ₂ in ground state → KOKU Interval = local φ₂ perturbation record. The Lagrangian framework from v2.0 is retained: L = L₁ + L₂ + λ·φ₂·F_μν F^μν. Uniform φ₂ produces constant renormalization of the photon Lagrangian → constant c. Three falsifiable predictions using IceCube, LIGO/Virgo, and VLBI archival data are retained. The adversarial objection "why c and not other constants?" is formally answered: other constants are quantities within spacetime; c is the invariance of the structure that makes quantities possible. These are not the same kind of invariance.