The sociologist mapped belief the way an epidemiologist maps infection. The rumor had started in the northeast corner of the district — the coffee shops where the early adopters gathered — and spread southwest, one block at a time, until the whole neighborhood believed it. Then the newspaper retraction hit. But retractions don't travel like rumors. Only the most recently convinced — the southwest corner, the people who had heard it last and held it most loosely — let go. Everyone else was too invested. The bottom-left quadrant cleared while the rest held. By the next survey, even those holdouts had come back around.