Preprint Global Complexity–Stability Theory (GCST): A Thermodynamic Resolution to the Fermi Paradox Rate-Induced Collapse, Lunar Habitability Criterion, and Galactic Stability Mapping

The Fermi Paradox — the apparent absence of extraterrestrial technological civilizations — is explained within Global Complexity–Stability Theory (GCST) as a universal stability bound rather than biological rarity. GCST asserts that accelerating complex systems collapse when complexity growth rate α exceeds recovery capacity γ: Technological civilizations represent extreme acceleration cases, leading to Rate-Induced Collapse (R-collapse) before interstellar capability. We introduce the Lunar Habitability Criterion: large moons elevate γ via tidal dissipation, axial stabilization, and biogeochemical cycling. Planets without such moons (e.g., Venus) suffer low γ, triggering early biospheric collapse. GCST modifies the Drake equation with survival factor S = exp(−α/γ), reducing N to ~0–5 per galaxy. A Galactic Biosphere Stability Map peaks at 6–10 kpc. Venus analysis shows absence of a moon with M ≥ 0.3–0.5 M_Moon caused G < 1 and runaway greenhouse transition. This provides a testable, thermodynamic resolution to the Fermi Paradox.