Hawking-Moss Vacuum Decay in Cosmic Voids: A Possible Mechanism for the Hubble Tension

We propose a novel mechanism for quantum vacuum decay in cosmic voids, wherein the reduced matter density leads to geometric suppression of the effective potential barrier. Using Coleman-De Luccia (CDL) instanton techniques and Hawking-Moss transition theory, we demonstrate that voids with radii R > 180 Mpc undergo unsuppressed vacuum transitions with Euclidean action SE ≲ 1. Our numerical analysis reveals two distinct regimes: (1) Hawking-Moss global fluctuations for low coupling constants (λ < 10⁻⁵), and (2) CDL bubble nucleation for higher couplings. The void evolution model predicts critical transitions at t ≈ 17 Gyr for supervoids, potentially creating localized regions of new matter. This mechanism naturally explains the Hubble tension (H₀ = 73 vs 67 km/s/Mpc) through enhanced local expansion near voids, with testable predictions for ISW stacking, peculiar velocities, and H(r) measurements. Parameter space exploration identifies optimal values λ ≈ 10⁻⁴, v ≈ 0.15 mPl for physical realizability. We emphasize that this is a proof-of-principle theoretical model requiring observational verification; definitive tests will be possible with upcoming surveys (Pantheon+, DESI, Euclid, Roman). Our findings suggest that cosmic voids may serve as natural laboratories for quantum field theory in curved spacetime, with implications for the multiverse hypothesis and cyclic cosmology.