For years, researchers have been studying the physics of crowds. Researchers think fluid dynamics could provide insights for how to make crowds safer.
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zamrznutitonovi/Getty Images
For years, researchers have been studying the physics of crowds. Researchers think fluid dynamics could provide insights for how to make crowds safer.
zamrznutitonovi/Getty Images
What do large crowds of people and water have in common?
They both act like fluids.
A clear example of the fluid dynamics at play in crowds is the masses at the San Fermín Festival in Pamplona, Spain. For a week each July, festival goers celebrate the running of the bulls. At noon on the first day of the festival, around five thousand people gather in the town square and wave a red handkerchief. The crowd is so dense that it would be like fitting 900 people in a one bedroom apartment. And, as festival goers cheers and sways, the movement looks like ripples of water.
Denis Bartolo is a physicist at the Institute of Advanced Education in Lyon, France. For four years, he and fellow researchers filmed the movements of the San Fermín festival crowd from rooftops.
Bartolo notes that while “dense crowds by themselves are not dangerous,” spontaneous movement in dense crowds can develop into something dangerous. Case-in-point: Ten fans died in a crowd crush during the 2021 Astroworld festival in Houston.
In the past it was thought that crowd movements were random, chaotic.
But in this study published Wednesday in the journal Nature, Bartolo and his team were able to break down the physics of the crowd’s fluctuations. They modeled the crowd and confirmed it acted like a fluid. For the first time, found that dense crowds followed recurring predictable patterns.
“Because these spontaneous motions are periodic in time, they are very easy to detect and they are very easy to detect very early on before they become dangerous,” says Bartolo.
The researchers hope that these findings can help authorities monitor and then intervene if a crowd starts exhibiting this kind of periodic behavior. Being able to model the physics of how a dense crowd moves brings us one step closer to figuring out what to do when they get dangerous.
So what can you do in the meantime?
If you feel like a dense crowd you’re in might be becoming dangerous, Bartolo suggests staying away from rigid walls. “You want to stay in the bulk. Do not go to the boundaries,” he says. Bartolo also advises people to not sit down or get low to the ground.
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Today’s episode was produced by Rachel Carlson and Jordan-Marie Smith. It was edited by Rebecca Ramirez and Christopher Intagliata. Tyler Jones checked the facts. Kwesi Lee was the audio engineer.
