Gravity as Vacuum Relaxation: A Geometric Framework for Galactic Dynamics and the Non-constraining Nature of the CMB Blackbody Spectrum

We propose the Differential Vacuum Relaxation Theory of Gravity (DVRT), which reconstructs the origin of gravity from a geometric perspective: the vacuum possesses an intrinsic affine geometric structure, matter is a local excitation of the vacuum geometry, and gravity emerges as a macroscopic restoring force arising from the spontaneous relaxation of excited states toward the vacuum ground state. We construct a complete scalar-tensor action and rigorously derive the coupled field equations. We analytically prove the screening mechanism: in high-density regions the model reduces exactly to general relativity; in the low-density outer regions of galaxies it automatically generates a correction term that produces flat rotation curves. A full MCMC fit to the SPARC dwarf spiral galaxy NGC 6503 is performed, matching observations without invoking cold dark matter. Regarding the CMB constraint controversy, we strictly distinguish the Planck blackbody spectrum from the acoustic power spectrum, quantitatively derive the critical redshift z_{\mathrm{crit}} \approx 9, and prove that at recombination z \approx 1100 the scalar correction is fully screened. The model can be distinguished from mainstream theories via gravitational lensing and stellar velocity dispersions.