The Θ–Ψ Framework: A Geometric Solution to Large-Scale Structure Anomalies

Recent spectroscopic surveys (DESI Year 1, Euclid Early Release) reveal a 4–5σ morphological tension: the largest cosmic voids (R > 150 Mpc) are significantly rounder (e = 0.11 ± 0.04) than ΛCDM simulations predict (e = 0.35–0.55). This "roundness reversal"—where larger voids are less elongated than smaller ones—has no conventional explanation within gravitational instability models. We propose that this anomaly, along with flat rotation curves, cluster mass excesses, the CMB Cold Spot, and the Hubble tension, arises from a single geometric source: a static, wavelength-limited tensor Θ projected from frozen 5D bulk curvature onto our 4D brane. When superposed with ordinary baryonic curvature Ψ, the resulting interference pattern naturally sculpts: Near-spherical supervoids (due to Θ-null exclusion zones) Sharp filamentary ridges (from constructive interference) Radially aligned outflows (driven by ∇Θ gradients) Key Features: Zero free parameters beyond the observed ~120 Mpc wavelength (derived from warped extra-dimension hierarchy scale) 11 falsifiable predictions testable by Euclid, Rubin/LSST, DESI, CMB-S4, and LISA (2026–2035) Immediate falsification criteria: Any single failed prediction rules out the pure-geometric interpretation Hybrid-ready framework: Naturally accommodates particle dark matter below ~10 Mpc if predictions partially fail Relation to Prior Work:This framework does not modify general relativity, Einstein's field equations, or the Friedmann equations. It introduces only a frozen scalar background (analogous to spatial curvature) that affects structure formation above ~10 Mpc scales. The model is fully compatible with CMB+BAO constraints and preserves all successes of ΛCDM on small scales.