Constraints on a Saturating, Non‑Newtonian Substrate Model from GW150914 and GW190521
Abstract We test predictions of the Finite-Response Coupled Field Dynamics (FRCFD) model—a saturable, non‑Newtonian substrate that replaces singularities with regime changes—using gravitational wave data from GW150914 and GW190521. Specific predictions examined include a fixed doublet near 200.2 Hz, amplitude modulation at the orbital frequency, two independent frequency tracks in the inspiral, spectral broadening, and a frequency “hook” (exponential recovery) in the ringdown. All predictions yield null results or inconsistent cross‑detector signals. We place upper limits on the model’s viscosity parameter η ≲ 2.5 (95% CL) from GW150914. For GW190521, we find no robust, detector‑consistent evidence for a frequency hook. The FRCFD framework remains mathematically coherent but is not yet supported by empirical evidence. 1. Introduction General Relativity (GR) predicts singularities where curvature diverges and the theory ceases to desc...