The Absolute Upper Bound of the Hubble Constant: Vacuum Energy, the Margolus-Levitin Limit, and the Physical Ceiling of Cosmic Expansion in QGEFT

Paper 90 does not claim a derivation of the exact numerical value of Λ, a complete quantum theory of gravity, or a modification of Friedmann cosmology at the present epoch. It does show that, within the QGEFT accounting, the vacuum allocation budget (exact Margolus-Levitin rate 4ρ/h ≈ 3.6–6.0×10²⁴ nodes s⁻¹ m⁻³, one Planck length per allocated node) yields an absolute upper bound of the Hubble constant H_max ≈ (5.8–9.8)×10⁻¹¹ s⁻¹ (order 10⁻¹⁰ s⁻¹); that the observed universe (H0 = 70 km/s/Mpc) uses only (2.3–3.9)×10⁻⁸ of this capacity — an idle cosmic processor; and that the bound is falsifiable, since any expansion rate above ~10⁻¹⁰ s⁻¹ at any epoch would exceed even the maximal, loss-free allocation budget of the vacuum.