On Black Friday, millions of Americans will flood shopping establishments hunting for deals and potentially crushing each other in the process. Human stampedes, whether they happen at a Best Buy or an EDM concert, can be dangerous moments where collective motion overwhelms and overtakes conventional social norms.
In a paper released Wednesday, a team of Harvard and Uppsala University researchers explain how mass gatherings become dangerous. Using computational tools, they were able to predict the risks that naturally arise when people are together in a dense, shoulder-to-shoulder crowd. If you find yourself in a packed crowd, they note, you shouldn’t expect human decency to save you. The movement patterns they observed indicate that people in a crowd lose control over how they collide with others, which can lead to potentially lethal pressure.
The researchers originally began this research examining the way the people move during heavy metal concerts, which gave way to broader insights into the physics of crowd formation.
“We were staring at the concert data when we realized that there were direct similarities with rallies, protests, and Black Friday sales events,” study author Jesse Silverberg, Ph.D., explained in a statement. “The more we dug, the richer the physics became. Pretty soon we found ideas from materials science and field theory could be applied directly to human crowds in extreme situations.”
The researcher’s computational physics model found that people in high-density crowds stream toward a common point of interest. People closest to this point of interest are the ones who are packed together the closest. While collisions between people can be random, the researchers were able to determine what they refer to as a “hidden order.” The physics of collective motion, they note, can accurately predict that people will move upwards and toward the central point, which, on Black Friday, may very well be a 70 percent off TV or iPhone 7. When there isn’t a central point of interest, the patterns of movement are less dangerous.
Random crowds also contain what the researchers call “soft spots.” These spots are where humans get jerked around the most if the crowd moves suddenly. These people are also the ones who are most at risk of being trampled. Stampedes are not only a danger to a person’s vital organs; they also trigger a sense of panic in other people within a mob, which can cause further “crowd crushing.”
“With Black Friday around the corner and a broad rise in global political demonstrations, our advice to minimize risk is to be aware of your surroundings,” the researchers advise in an accompanying video. “Even with the best intentions, people packed shoulder-to-shoulder don’t have full control of how they move. Random, unexpected collisions between neighbors add up to serious collective effects.”
Black Friday deals are nice — but coming away unscathed after trying to buy a TV is nicer.