“self-propulsion and flocking parameters were dominated by noise”
The behaviour of crowds at heavy metal concerts is surely a topic close to the hearts of many readers of the Physics arXiv Blog. In these crowds, fans often form circles called mosh pits and then run together with physical abandon, bouncing off one another with arms flaying and legs kicking.
“The collective mood is inﬂuenced by the combination of loud, fast music (130 dB, 350 beats per minute), synchronized with bright, ﬂashing lights, and frequent intoxication,” say Jesse Silverberg and pals at Cornell University in Ithaca.
The resulting disorder may sound chaotic but Silverberg and co say it turns out to have all the properties of self-organised emergent behaviour. Today, they reveal the results of their study of this phenomenon.
Silverberg and co gathered their data by examining videos of mosh pits on You Tube, such as this one and this one. These crowds contain anything from 100 to 100,000 people. After correcting for camera shake and distortions in perspective, they used particle image velicometry techniques to measure the collective motion of moshers.