Human collective motion are often driven by a common goal. What the goals are vary widely among social contexts. On a crowded market place pedestrians lines arise to allow (some) movement, while the urge to escape a burning building often leads to a jammed exit. I’ll talk about a social context where the sole goal is to violently move around. This, as shown by [1], leads both to a gaslike state called a “mosh pit” and to a ordered vortexlike state called a “circle pit”. Using a simple model for people, and quantitative analysis of hundreds of youtube videos, the authors show a phase transition between those two states.
