Structural Gravity Theory v3.0: A Quantitative Physics Validation Framework

Structural Gravity Theory (SGT) v3.0 presents a structural-field (χ) extension of General Relativity within a quantitative Physics Validation Framework. The framework begins from a unified action and develops a second-order, Ostrogradsky-free theory satisfying no-ghost, gradient-stability, hyperbolicity, and gravitational-wave speed constraints (GW170817). The theory is quantitatively evaluated using multiple independent observational probes, including: • Gravitational-wave observations (GW150914, GW190521, GW230529)• Event Horizon Telescope black-hole shadows• Planck CMB• DESI BAO• Pantheon+• Weak-lensing surveys• Big-Bang nucleosynthesis• Large-scale structure and growth of cosmic structure The complete validation framework consists of twenty-six self-contained quantitative figures covering: • Theoretical foundations• Effective field-theory mapping• Screening mechanisms• Compact objects• Black-hole shadows• Quasi-normal modes• Ringdown consistency• Cosmological validation• Bayesian model comparison• Allowed parameter regions• Observable-wise falsification criteria• Future observational roadmap An integrated Bayesian comparison yields ΔlnZ_total = +14.98 relative to General Relativity on the adopted scale. The present release corresponds to Evidence State 3 (Computed Consistency), while future observations are expected to determine progression toward prospective validation. This Zenodo record contains the complete SGT v3.0 release, including: • Full manuscript (PDF)• 26 publication-quality source figures• README• CITATION.cff• Zenodo metadata• LICENSE• CHANGELOG• Complete file manifest License:Creative Commons Attribution 4.0 International (CC BY 4.0).