Geometric Explanation of Dark Energy and the Vacuum Catastrophe

Dark energy is one of the greatest puzzles in contemporary physics. The vacuum energy density predicted by quantum field theory exceeds the astronomical observation value by a factor of 10¹20—the largest discrepancy between theory and observation in the history of physics. The standard cosmological model treats the cosmological constant Λ as a free parameter to fit observations, without providing its physical origin. This paper demonstrates that the geometric cancellation mechanism of Postulate 3 (the spacetime emergence hypothesis) of the Order Parameter Spacetime Theory automatically eliminates the gravitational effect of the zero-point energy of quantum fields, so that it does not contribute to the cosmological constant. After geometric cancellation, the residual dark energy density originates from the ground-state quantum mutual information background I₀ contributed by the degeneracy of the order-parameter field ground state. Starting from the information-Einstein equation in an FLRW background, Paper 4 derived ρ_Λ ∼ H₀² MPlanck² ∼ 10⁻⁴⁷ GeV⁴, which is consistent with the observed dark energy density in order of magnitude. This is not fine-tuning but an inevitable consequence of the geometric structure. If the information-theoretic background interpretation holds, the dark energy equation of state w (z) should evolve with redshift and cross −1 in the recent past—a feature already qualitatively consistent with DESI DR2 observations. This paper also discusses an extended corollary: if the ground-state mutual information background is a real physical effect, the vacuum should possess a non-zero information entropy density, whose expected magnitude δT/T ∼ 10⁻¹⁰ lies within the detection range of the future PIXIE satellite. This provides an independent test channel that distinguishes this theory from phenomenological dynamical dark energy models.