Structural Cosmology v4.0: Structural Origin of Gravity — A Proposed Pre-Metric Framework for Emergent Gravity

Structural Cosmology v4.0 extends the precision observational framework established in Structural Cosmology v3.0–v3.9 toward a more fundamental question: Why does gravity exist? This work introduces the Structural Dynamics of Gravity (SDG) framework, a proposed pre-metric structural approach exploring whether an effective description of gravity may emerge from structural differentiation rather than being fundamental. The framework integrates a pre-metric structural field Ψ(x,τ), information-density gradients, metric emergence, structural propagation, effective action, and General Relativity recovery into a unified theoretical architecture. It further connects these concepts with potentially observable signatures in gravitational waves, CMB tensor modes, and large-scale structure. A falsifiability network (C91–C100) is proposed, covering gravitational-wave propagation, CMB polarization, screening mechanisms, weak lensing, growth-rate evolution, and cross-probe consistency. The central falsifiable prediction is the Geometry–Growth Projection Test (GGPT), providing a near-term observational target for Euclid DR1 and future cosmological surveys. All figures and models are presented as illustrative, proposed frameworks. No confirmed detections or definitive claims are made. This Zenodo preprint establishes a timestamped public record of the proposed SDG framework and its associated observational roadmap.