By analyzing the flocking behavior of heavy metal concert goers in mosh pits, Cornell University researchers discovered that their collective actions closely approximate the way particles work in a two-dimensional gas.
While it might seem like frivolous work, this study has serious implications for understanding how people move in panic situations, like when fleeing from an emergency or when embroiled in a riot. By analyzing and simulating seemingly chaotic human behaviors — like flocking situations in this case — the researchers built a simplified model that could help designers create buildings and other structures to mitigate these risks.
And indeed, what could be better than studying mosh pits and circle pits? Long a staple of heavy metal and punk shows, they exemplify chaotic, swarming human behavior. In mosh pits, concert attendees move randomly, colliding with one another in an undirected fashion. A circle pit is where attendees form a swirling vortex.
Lead researcher Matthew Bierbaum analyzed and modeled these motions by watching mosh pits and circle pits featured in YouTube videos.
“Qualitatively, this phenomenon resembles the kinetics of gaseous particles, even though moshers are self-propelled agents that experience dissipative collisions,” writes Bierbaum in the study. His models show that moshers collide with each other randomly and at a distribution of speeds that resembles particles in a two-dimensional gas.
Mosh pit simulation:
Real mosh pit (at an In Flames concert):
Circle pit simulation:
Real circle pit (at a Killswitch Engage concert):
The researchers elaborate at their website:
Flocking simulations model living beings as simple particles, reducing complex behavioral dynamics to a few basic rules. In our case, we used two populations of simulated moshers, which we dub Mobile Active Simulated Humanoids, or MASHers. Active MASHers move around and have a tendency to follow their neighbors (in the technical literature, this is called "flocking"), while passive MASHers prefer to remain stationary. Mixing active and passive MASHers together, we found that when random collisions dominate the tendency to flock, the statistics of mosh pits are quantitatively reproduced. On the other hand, when the situation was reversed and flocking dominated randomness, we found an ordered vortex-like state. Looking back at videos of metal concerts, we found that actual moshers exhibited this vortex-like phenomenon too. These so-called "circle pits" spontaneously emerge from the simulation and are an interesting example of collective behavior in humans.
Recently, when speaking at the American Physical Society, Bierbaum remarked: “How these supposedly intelligent beings behave like an ideal gas, I don’t know.”
And interestingly, of all the circle pits analyzed, 95% of them moved in a clockwise direction, which Bierbaum attributes to humans’ dominant right-handedness.
The results are now available at the preprint site arXiv: “Collective Motion of Moshers at Heavy Metal Concerts.” More at the researchers’ website, Cohen Group.