Geometry as Description, Not Cause
Chapter 5 — Gravity, Black Holes, and Breakdown
Part I — Geometry as Description, Not Cause
5.1 The Persistent Mistake: Treating Geometry as an Agent
Gravity is often described as the most elegant interaction in physics. It is also the one most persistently misunderstood at the interpretive level.
This misunderstanding does not originate in general relativity itself. The Einstein field equations are precise, restrained, and extraordinarily successful. The difficulty arises in how their content is habitually narrated.
The now-familiar slogan — “spacetime tells matter how to move, and matter tells spacetime how to curve” — is a useful pedagogical compression. It becomes a mistake the moment it is taken literally.
Geometry does not act. Spacetime does not exert influence. Curvature is not a force.
These statements do not challenge general relativity. They restore it.
The temptation to treat geometry as a causal agent is understandable. General relativity replaces the Newtonian gravitational force with geometric structure, and the resulting formalism is both compact and predictive. In eliminating force as a primitive, however, popular and even professional discourse quietly introduced a substitute agent: spacetime itself.
This substitution is not mandated by the mathematics. It is an interpretive aftereffect.
Curvature appears in the equations as a relational descriptor: a way of encoding how intervals, angles, and geodesics behave under the constraints imposed by stress–energy. At no point does the formalism require that spacetime do anything. Yet the language of “influence,” “guidance,” and “telling” entered gradually, driven by the need to replace an intuitive picture of force with something equally vivid.
Once geometry is spoken of as acting, several interpretive pathologies follow automatically: spacetime is reified as a physical substance; curvature is granted causal power; motion is treated as being produced rather than permitted; and vacuum is tacitly upgraded from absence to medium.
Reactive Substrate Theory rejects this inflation at the outset.
Under RST, geometry is read strictly as description. The metric encodes how difficult it is for a finite substrate to support particular patterns of motion and persistence under constraint. It summarizes stress, not agency.
When a body follows a geodesic, nothing is pushing it along that path. The system simply continues in the mode that minimizes local retuning under existing constraints.
Gravity does not act. Spacetime does not push. Curvature does not cause.
General relativity never required these claims. They were added in narration. Reactive Substrate Theory removes them.