Conservation of Information Processing Capacity and its Resolution of the Cosmological Constant Problem

Unifying quantum mechanics and general relativity remains a central challenge in theoretical physics, with the cosmological constant problem—the 120-orders-of-magnitude discrepancy between quantum field theory vacuum energy and observed dark energy—being a prime manifestation. This work introduces a novel perspective from quantum information and holography, proving a macroscopic conservation law for causally isolated quantum gravitational systems: under strict adiabatic evolution, a system's Information Processing Capacity 𝒞 (the theoretical upper bound on its internal quantum information exchange rate) is an adiabatic invariant. Expressed as 𝒞 = κ·(A c / ℓₚ³), where A is the area of the causal boundary, this law is derived from four foundational premises: quantum unitarity, a generalized holographic principle, gravitational self-consistency, and the quantum adiabatic condition. It is independent of any specific model of quantum gravity. Applying this principle to the late-time universe—modeled as a de Sitter-like system bounded by a cosmological event horizon—and invoking a saturation hypothesis alongside the Landauer principle, we derive from first principles, without any fine-tuning, the observed scaling law for dark energy density: ρ_Λ = 3H²/(8πG). This provides a radical reinterpretation: dark energy is not a microscopic vacuum energy but a geometric effect emerging from the macroscopic, holographic constraint on cosmic information processing. The theoretical prediction, ρ_Λ ≈ 8.7 × 10⁻²⁷ kg/m³, is in remarkable agreement (within a factor of ~1.5) with Planck satellite observations. The theory leads directly to two key, testable predictions for the next decade: A small but detectable deviation of the dark energy equation of state from -1: |1+w| ~ 0.01-0.02, discernible by the Euclid satellite and the Legacy Survey of Space and Time (LSST). Minute Lorentz symmetry violation at ultra-high energies, detectable via energy-dependent time delays in gamma-ray burst photons by the Cherenkov Telescope Array (CTA). This work establishes a new bridge between quantum information, gravity, and cosmology, offering a clear and falsifiable path for quantum gravity phenomenology.