Spatial Theory: On the Gravitational Effect of Spatial Configuration of Matter in General Relativity - An Extension to the Source Term of Einstein's Field Equation

General Relativity establishes the core idea that ”matter-energy determinesspacetime geometry” and has achieved extremely high verification accuracy withinthe solar system scale. However, on galactic scales, there is a systematic devia-tion between the observed rotation speeds and the gravity expected from visiblebaryonic matter alone.This paper points out that this deviation originates from the ”continuous smoothapproximation” commonly used in current astrophysical calculations of matter dis-tribution – smoothing out spiral arms, star clusters, gas clumps and other geometricstructures before substituting them into the field equation, which essentially mod-ifies the real physical input conditions.By analyzing the rotation curve data of 175 galaxies in the SPARC galaxy sam-ple, and introducing independent rotation curve measurements of the Milky Way(Jiao et al. 2023), this paper finds that there is a clear and systematic positive cor-relation between the gravitational response deviation and the spatial configurationof matter. Based on this, this paper proposes that the geometric configuration ofthe spatial distribution of matter itself constitutes an independent physical degreeof freedom in the source term of the Einstein field equation.