RMB Core Theory 2.1 presents the unified and mathematically consistent foundation of the Space–Matter–Motion (RMB) framework.This work consolidates all field definitions, the Lagrangian formulation, and the resulting master equation that underlies every previous RMB publication (RMB I–VII). Core Contributions 1. Definition of the central RMB fields Potential field: Φᵤ = ρ c² vᵤ Field tensor: Fᵤᵥ = ∂ᵤΦᵥ − ∂ᵥΦᵤ Motion tensor: Mᵤᵥ = ρ vᵤ vᵥ + αᴿᴹᴮ Fᵤᵥ These objects unify matter flow and spatial deformation into a single dynamical structure. 2. Full Lagrangian formulation The RMB Lagrangian yields the master field equation ∇ᵘ Mᵤᵥ = 0which replaces the geodesic equation of General Relativity in the RMB framework. 3. Linearisation and wave equations The theory predicts non-dispersive inertial-vorticity waves with wave speed cᴿᴹᴮ = c √(αᴿᴹᴮ / ρ₀). 4. Newtonian limit and rotation curves The RMB correction term aᴿᴹᴮ(r) = −(αᴿᴹᴮ / ρ₀) · d/dr [v(r)/r]produces flat galactic rotation curves without invoking dark matter.This is validated using SPARC data. Scope Chapters 1–7 define the core theory.Speculative phenomena (φ-scaling, resonance structures, Schumann–LHC correlations, the 800 Hz signal) are placed strictly in Appendix A and are not part of the core model. Purpose This is the official consolidated reference for all RMB field equations, ensuring consistency across all future RMB publications and offering a clear, testable physical framework that connects laboratory physics, astrophysics, and cosmology.