Thermodynamic Saturated Boundaries: A Closed Cosmological Heuristic Based Exclusively on Fundamental Constants

Description Methodological Update Note (v2 to v3): This updated and definitive version (v3) marks a stage of theoretical maturity. We transparently acknowledge that previous versions contained conceptual errors, mathematical inconsistencies, and unsupported heuristic excesses. In this final, streamlined version, all methodological flaws have been rigorously corrected. All ad-hoc parameterizations, curve-fitting attempts, and artificial structural invariants—specifically the previously proposed "Costa Constants"—have been entirely eliminated. The framework has been strictly reduced to a pure, parameter-free closed-system heuristic, evaluated exclusively through 5 concrete and falsifiable boundary predictions. Abstract: We propose a strict heuristic treating the universe as an isolated, closed thermodynamic system bounded by fundamental quantum and relativistic limits. This model introduces zero free parameters, scalar fields, or ad-hoc variables, relying exclusively on CODATA fundamental constants (c, G, , kB) and a fixed mass-energy budget (MU ≈ 1.50 × 10⁵³ kg). From these classical thermodynamic constraints, we derive explicit, mathematically rigorous, and empirically falsifiable predictions. Key Findings (The 5 Falsifiable Predictions): This mathematically closed geometry dictates that any future theory of quantum gravity must respect macroscopic thermodynamic saturation limits. The framework yields the following boundary conditions: The Non-Zero Mass Floor for Gauge Bosons: Infinite wavelengths are geometrically prohibited, enforcing a strict mass floor (mₘᵢₙ ≈ 1.57 × 10⁻⁶⁹ kg) for photons and gravitons. Holographic Resolution of the Vacuum Catastrophe: By converting the 2D Bekenstein informational capacity of the apparent horizon into thermal energy via Landauer's principle, the macroscopic vacuum density perfectly matches the observed cosmological constant (≈ 2.9 × 10⁻¹⁰ J/m³), organically eliminating the 10¹²² discrepancy of Quantum Field Theory. Truncation of Hawking Evaporation (Planck Remnants): Geometric contraction halts at the Planck volume limit, prohibiting absolute evaporation and leaving a stable, information-preserving remnant (Sᵣₑₘₙₐₙₜ = π kB). Static Equation of State for Dark Energy: Entropic boundary tension is a static property of spacetime geometry ($w = -1$), not a dynamic fluid. Absolute Growth Ceiling for Supermassive Black Holes: Black hole coalescence is fundamentally capped by the global Misner-Sharp boundary limits. Conclusion: This heuristic does not attempt to construct a microscopic theory of quantum gravity. Instead, it demonstrates that when the universe is treated strictly as an information-conserving geometric system, longstanding cosmological anomalies—most notably the vacuum catastrophe—naturally dissolve. The strength and integrity of this framework rest entirely on its Popperian falsifiability.