Thermodynamic Shortcuts and Civilisational Trajectories: Evolutionary Mismatch as a Universal Filter to the Fermi Paradox

Traditional astrobiology and SETI frameworks overwhelmingly rely on Kardashev-style paradigms, assuming that technological civilisations inevitably scale through expanding energy capture and wasteful technosignatures. This paper introduces a complex systems framework that reframes the Fermi Paradox through the lens of thermodynamic efficiency, biospheric constraints, and evolutionary mismatch. We argue that planetary-scale technology unlocks existential levers long before a species can evolve the social, psychological, and institutional firmware required to govern them. Prior to industrial energy subsidies, civilisations remain constrained by a "sawtooth baseline" of cyclic demographic climbs and epidemiological crashes—a natural filter that maintains biospheric equilibrium. When technological shortcuts bypass this baseline, species encounter the Cognitive Asymmetry Trap. By modeling civilisational persistence as a function of thermodynamic gain versus governance capability S = ΔT_tech / ΔE_gov, we demonstrate that "quiet," highly efficient, homeostatic persistence (Path A) is the primary survival vector for long-lived species. Conversely, loud, expansionist civilisations represent inherently transient, self-limiting anomalies. The "Great Silence" is therefore not an absence of intelligent life, but a direct consequence of thermodynamic and evolutionary mechanics.