Heavy Metal and Emergent Behavior

You may think that moshing and disordered 2D gases don't have much in common but Jesse Silverberg of Cornell University contends otherwise. He says that mosh pits act just like disordered gases and people in circle pits act in an ordered vortex-like state. From the article: "Silverberg and co gathered their data by examining videos of mosh pits on You Tube... 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. What they discovered was that the speed distribution of moshers closely matches that of molecules in a 2D gas at equilibrium."

General phenomena, NKS

[Janek Kozicki]

You might be interested in new kind of science [wolframscience.com], where Stephen Wolfram argues that fluid (and gas) movement is a general pehonomena, which can be replicated using only very basic rules. And therefore must occur in very broad range of materials, regardless of their underlying precise rules. And he is right. I am no surprised that this also applies to heavy metal crowds.

Hi, Heavy Metal fan here

[L4t3r4lu5]

s/Mosh Pit/Circle Pit/g;

They're different things. A mosh pit is where folk charge from the edge to the centre, and is pretty disorganised. Typically you'll find this with Death Metal, Speed Metal, and other very fast beat genres where there is no discernable difference between, say, verse and chorus. Circle Pits are the phenomenom being investigated here, where they start moving in a fairly ordered vortex around the centre, before moving into the centre when the band "drops the bass", then moves back to the circle when there's a "lull" (comparitively).

Hope this helps, science types.

And Most Crowd Distaters are not due to Stampedes

[Diamonddavej]

And this reminds me of the Crowd Quake. Most crowd disasters are not due to Stampedes, where mass panic breaks out and people rush headlong into a choke point and get crushed. Researchers looking into the Love Parade Disaster discovered a hitherto unrecognised crowd dynamical process that can kill people in large crows - the Crowd Quake.

In normal crowds there's personal space between people, room to breath and move even a little bit. This personal space accommodates and cushions mass movement. However, at a critical point of density there's no personal space left and people are in full body contact. In this situation, mass movement efficiently transmits extreme forces through the crowd - the Crowd Quake. It's like changing a compressible gas into an incompressible solid, but people aren't incompressible. This is why crowd disasters happen so suddenly, it's like crystallisation from a gas.

See: Crowd Disasters as Systemic Failures: Analysis of the Love Parade Disaster http://arxiv.org/abs/1302.1886 [arxiv.org]