The Great Filter is a possible answer to a creepy question: if the universe is full of habitable planets, where is everyone?
The idea is that somewhere between ‘dead rocks’ and ‘galaxy-spanning civilizations,’ there is a step that almost no species survives. It could be behind us (life itself is rare). Or it could be ahead of us (technological civilizations tend to self-destruct).
AI safety researchers take this seriously. If the Filter is ahead of us, artificial intelligence might be the trigger.