The physics of high-density crowds (and rock concerts)

During mass events such as concerts, parades, sporting events, and pilgrimages, crowd density can become exceptionally high, causing the emergence of sometimes deadly collective motion such as crowd turbulence and density waves. Understanding the physical mechanisms underlying collective motion in such extreme cases constitutes a fundamental step in predicting and preventing the dangers arising at mass gatherings.

I will give an overview of how, taking inspiration from the physics of jammed granular materials, we were able to identify Goldstone modes, soft spots, and stochastic resonance, as potential mechanisms for dangerous emergent phenomena in crowds [1,2]. Then, I will present the recent insights gained by extending these techniques to the video footage from a rock concert, and discuss the potential of this approach in forecasting crowds’ collective motion.


[1] A. Bottinelli, D.T.J. Sumpter, J.L. Silverberg, “Emergent structural mechanisms for high-density collective motion inspired by human crowds”, PRL (2016)

[2] A. Bottinelli, J.L. Silverberg, “How to: using mode analysis to quantify, analyze, and interpret the mechanisms of high-density collective motion”, Frontiers (2017)