Rotation-Induced Microscopic Binding and the Emergence of a Contracting Rod A Finite-Stiffness Effective Theory with a Microscopic Mediator Model, Quantitative Thresholds, and Experimental Controls

A rotating extended body is ordinarily expected to develop outward centrifugal strain. This paper presents a conditional effective theory in which bulk rotation instead couples to an internal activity variable, strengthening the attractive binding between constituents. For a general repulsive–attractive pair potential, two exact theorems are proved: the equilibrium bond separation decreases monotonically with rotation, and both the microscopic stiffness and the coarse-grained elastic modulus increase. Coarse-graining a chain of such bonds produces an emergent “contracting rod” whose preferred length shortens as angular velocity rises. For a closed ring, the rotation-dependent preferred proper circumference combines with relativistic circumference closure to yield a generalized radial accommodation map that remains subluminal for all finite parameters. A parity‑even finite‑stiffness locking sector and a microscopic mediator toy model are provided, and dimensionless competition criteria, illustrative thresholds, and falsifiable low‑rotation quadratic signatures are given. Throughout, internal structural attraction is carefully distinguished from a universal external gravitational field.