> A long time ago I did a bit of work on disaster alert systems. They’re not dissimilar to fire alarms. The engineered purpose of a fire alarm is not merely to

> A long time ago I did a bit of work on disaster alert systems. They’re not dissimilar to fire alarms. The engineered purpose of a fire alarm is not merely to let people know there is a fire. Many will have already perceived the fire. The alarm, buttressing training delivered far before the alarm rings, gives you unquestionable and immediate permission to evacuate. We know that otherwise some people, smelling smoke and feeling uneasy, would look around the room, see other people not moving, and conclude “Who am I, to disrupt everything going on by shouting ‘Fire! Fire! Fire!’?” The history of humanity has seen far too many rooms where no one shouted ‘Fire!’ early enough. This alone is a pretty interesting point. Can apply to many other systems that are much less significant than literally "life or death."