Stuff You Should Know How Crowds Work
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Feb 17, 2026 A tour through the science and psychology of crowds, from fluid dynamics and lane formation to how density creates crush risks. Tragic crowd crushes and mismanagement highlight safety challenges. The conversation contrasts old contagion theories with evidence of prosocial behavior, explores deindividuation and emotional contagion, and examines how policing, alcohol, and weapons shape group outcomes.
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Crowds Behave Like Fluids
- Crowd movement often resembles fluid dynamics and can be modeled with physics concepts like orbital motion and social force.
- People unconsciously form lanes and coordinated movement without explicit leadership, creating cohesive group behavior.
1896 Moscow Stampede Example
- Josh recounts the 1896 Moscow coronation where a rumor about free souvenirs caused a stampede that killed 1,300 people.
- He uses it to illustrate how bottlenecks and back-pressure in crowds produce catastrophic crushes.
Density Predicts Danger
- Density thresholds predict danger: around six people per square meter movement becomes difficult and ten per square meter makes individual movement impossible.
- High densities place crowds on a razor's edge where a single trigger can create a deadly crush.
