Cosmological Acceleration from Scale-Space Metric Enthalpy Degradation: A Thermodynamically Consistent Resolution to the Dark Energy Problem

Abstract The cosmological constant problem and the late-time accelerated expansion of the universe are re-examined from the perspective of non-equilibrium continuum mechanics and horizon thermodynamics. Rather than postulating an ad hoc vacuum energy density Λ or an empirical scalar field, we formulate cosmic expansion within a scale-space boundary framework where the irreversible conversion of coherent hydrodynamic work into boundary entropy generates an effective dissipative enthalpy drag. While standard relativistic viscous approaches typically introduce empirical constitutive power laws that result in severe cosmological age deficits (t0 ≪ 13.8 Gyr) and suppress linear perturbation growth (fσ8), our framework derives dissipative pressure from a first-principles scale-space action principle. The resulting dynamical system possesses a stable fixed-point attractor governed by dimensionless parameters (τ˜, x0) that naturally preserves the radiation and dust-dominated epochs before locking into a late-time de Sitter asymptotic phase. We perform complete numerical quadratures verifying that the expansion trajectory yields an age of the universe t0 = 13.78 Gyr and transition redshift zt ≈ 0.62, in strict agreement with observational constraints, while the restriction of dissipation to boundary horizon scales guarantees standard sub-horizon Jeans gravitational collapse.