The discovery of Axiomatic Physical Homeostasis (APH) and the finite Geometric Stiffnessof the vacuum (βQCD ≈ 1.91) necessitates a fundamental re-evaluation of economic theory atthe solar system scale. We propose a Relativistic Economics where value is not absolute, but isa function of the local vacuum stiffness metric. This paper defines the Distributed ConsensusStiffness (DCS) Protocol: a non-negotiable economic governance layer that imposes a PhysicsTax on trade between the Earth, Mars, and Venus stiffness zones. We demonstrate that a unifiedfree market is physically impossible due to the risk of entropic contamination (Sedenion Slag)from low-stiffness environments [3]. We derive the Stiffness Exchange Rate Mechanism requiredto maintain the topological stability of the Earth Sphere.