According to TechnologyReview.com, a team of researchers at Cornell University in Ithaca has found that the speed distribution of moshers at heavy metal concerts — where fans run together with physical abandon, bouncing off one another with arms flaying and legs kicking — closely matches that of molecules in a 2D gas at equilibrium.
Said Jesse Silverberg and his co-workers at Cornell: “Heavy metal concerts present an extreme environment in which large crowds of humans experience very loud music in sync with bright, flashing lights, often while intoxicated. In this setting, we find two types of collective motion: mosh pits, in which participants collide with each other randomly in a manner resembling an ideal gas, and circle pits, in which participants run collectively in a circle forming a vortex of people. We model these two collective behaviors using a flocking model and find qualitative and quantitative agreement with the behaviors found in videos of metal concerts. Futhermore, we find a phase diagram showing the transition from a mosh pit to a circle pit as well as a predicted third phase, lane formation.”