Criticism on the Logical Contradiction and Physical Essence of the Spacetime Curvature Theory in a Three-Dimensional Universe

General Relativity equates gravity with spacetime curvature and establishes a geometric interpretation system of gravity. This system can only approximately match the observation data through parameter fitting at the solar system scale, but its theoretical framework has inherent logical defects that cannot be self-consistent. Based on the objective reality of the real three-dimensional universe, this paper emphasizes that no celestial body in the universe exists in isolation. It is not only surrounded by a few nearby celestial bodies, but surrounded by countless cosmic substances and celestial bodies at different distances in all directions, and each substance has an independent gravitational effect. Celestial bodies in different directions and distances have completely inconsistent requirements on the direction and curvature of spacetime curvature. The theory cannot determine which curvature standard to follow, nor can it construct a special spacetime curvature form for countless differentiated gravitational demands, thus forming an irreconcilable fundamental logical paradox. At the same time, this paper analyzes the parameter fitting attribute of the theory, the explanatory gap of the large-scale cosmic structure, the incompatibility with the microscopic strong interaction and other defects. By comparing with the rigor and universality of Newton's system of universal gravitation, it clarifies that General Relativity deviates from the real physical operation mechanism of the universe.