The revolutionary nature of Einstein's theory of relativity lies in its redefinition of gravity from a mere "force" as a "geometric property" of spacetime. The most effective way to understand this is through thought experiments, and modern interactive technology allows us to dynamically visualize these experiments. The core is the construction of a controllable "mass-spacetime" feedback system: when a user performs an action (such as placing or moving a mass sphere), the system immediately calculates the corresponding change in spacetime curvature and presents it in real-time through visual language such as grid deformation and light deflection. This instantaneous and reversible causal feedback allows learners to actively explore, as if conducting an experiment, what would happen if the mass were greater or if photons were incident from different angles, thereby internalizing the profound principle that "matter tells spacetime how to curve, and spacetime tells matter how to move." By
