Gravissimo Solitons in Dynamic Substrate Theory: Axiomatic Foundations, Emergent Geometry, Singularity Resolution, and GWTC-3 Echo Phenomenology

Abstract For over a century, General Relativity has predicted the existence of spacetime singularities—regions of infinite density where physical laws break down—alongside absolute event horizons that provoke the black hole information loss paradox. This work presents the high-density mechanics of the Dynamic Substrate Theory (DST), modeling compact objects as macroscopic topological excitations termed Gravissimo Solitons. Within this continuous viscoelastic framework, gravitational collapse naturally saturates at a finite Planckian density (\rho_{\text{max}}), replacing central singularities with regular de Sitter-like cores (P = -\rho_{\text{max}} c^2) and bounded curvature scalars. Furthermore, absolute event horizons are replaced by porous pseudo-horizons, preserving unitarity and yielding explicit post-merger gravitational wave echo signatures (\Delta t_{\text{echo}} \approx 28.5\text{ ms}, reflectivity R \in [0.65, 0.85]) testable against GWTC-3 catalog data. Keywords: High-Density Mechanics, Singularity Resolution, Viscoelastic Vacuum, Gravitational Wave Echoes, Topological Solitons.