Global Complexity–Stability Theory (GCST): A Unified Framework for the Evolution of Complex Systems Across Scales

Abstract Global Complexity–Stability Theory (GCST) introduces a universal stability condition for dissipative complex systems: the index G = γ / (α C), where α is the complexity growth rate, γ is the dissipation rate, and C is structural complexity. Systems evolve toward the critical boundary Gc = 1, a state of maximal adaptability and sensitivity. The theory is anchored to fundamental constants c, G, ħ and derives the dark sector (ΩDM + Ω_Λ ≈ 0. 95) as accumulated structural debt D. A Lagrangian formulation, renormalization-group flow, and general covariance are provided. GCST unifies cosmology, galaxy dynamics, planetary habitability, and civilizational evolution, yielding testable predictions for Euclid, DESI, and Rubin Observatory.