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Collective Motion of Humans in Mosh and Circle Pits at Heavy Metal Concerts
Jesse L. Silverberg,
*
Matthew Bierbaum, James P. Sethna, and Itai Cohen
Department of Physics and Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
(Received 13 February 2013; published 29 May 2013)
Human collective behavior can vary from calm to panicked depending on social context. Using videos
publicly available online, we study the highly energized collective motion of attendees at heavy metal
concerts. We find these extreme social gatherings generate similarly extreme behaviors: a disordered
gaslike state called a mosh pit and an ordered vortexlike state called a circle pit. Both phenomena are
reproduced in flocking simulations demonstrating that human collective behavior is consistent with the
predictions of simplified models.
DOI: 10.1103/PhysRevLett.110.228701 PACS numbers: 89.65.Ef, 47.32.y, 87.15.Zg, 87.23.Cc
Human collective behaviors vary considerably with
social context. For example, lane formation in pedestrian
traffic [1], jamming during escape panic [2], and Mexican
waves at sporting events [ 3] are emergent phenomena that
have been observed in specific social settings. Here, we
study large crowds (10
2
10
5
attendees) of people under the
extreme conditions typically found at heavy metal concerts
[4]. Often resulting in injuries [5], the collective mood is
influenced by the combination of loud (130 dB [6]), fast
(blast beats exceeding 300 beats per min) music, synchro-
nized with bright flashing lights, and frequent intoxication
[7]. This variety and magnitude of stimuli are atypical of
more moderate settings and contribute to the collective
behaviors studied here (Fig. 1).
Thousands of videos filmed by attendees at heavy metal
concerts [8] highlight a collective phenomenon consisting
of 10
1
10
2
participants commonly referred to as a mosh
pit. In traditional mosh pits, the participants (moshers)
move randomly, colliding with one another in an undir-
ected fashion (Fig. 2(a); see Supplemental Material for
video metadata [9]). Mosh pits can form spontaneously
or at the suggestion of the performing band, but in both
cases, no micromanagement of individual actions is gen-
erally involved. Qualitatively, this phenomenon resembles
the kinetics of gaseous particles, even though moshers
are self-propelled agents that experience dissipative
collisions and exist at a much higher density than most
gaseous systems. To explore this analogy quantitatively,
we watched over 10
2
videos containing footage of mosh
pits on YouTube.com, obtained six that were filmed from a
suitably high position to provide a clear view of the crowd,
corrected for perspective distortions [10] as well as camera
instability, and used particle image velocimetry (PIV)
analysis [11] to measure the two-dimensional (2D) veloc-
ity field on an interpolated grid [Fig. 2(b)].
Video data of mosh pits were used to calculate the
velocity-velocity correlation function c
vv
, where we noted
an absence of the spatial oscillations typically found in
liquidlike systems [Fig. 2(b) inset] [12]. Generally, c
vv
was
well fit by a pure exponential, and for the video used in
Fig. 2, the decay length was 0: 39 0:03 m, which is
approximately human shoulder width. Taken together,
these findings offer strong support for the analogy between
mosh pits and gases. As a further check, we examined the
2D speed distribution. Previous observations of human
pedestrian traffic and escape panic led us to expect a broad
distribution not well described by simple analytic expres-
sions [2,13]. However, the measured speed distribution in
mosh pits was well fit by the 2D Maxwell-Boltzmann
distribution, which is characterized by the probability
distribution function PDFðvÞ¼ð2v=TÞe
v
2
=T
and tem-
perature T [Fig. 2(c) and inset] [14]. These observations
present an interesting question: why does an inherently
nonequilibrium system exhibit equilibrium characteristics?
Studies of collective motion in living and complex sys-
tems have found notable success within the framework of
flocking simulations [1523]. Thus, we use a Vicsek-like
FIG. 1 (color online). This photograph illustrates typical col-
lective behavior found in a mosh pit at heavy metal concerts.
Notice that some attendees are participating (foreground), while
others are not (background). Image courtesy of Ulrike Biets.
PRL 110, 228701 (2013)
PHYSICAL REVIEW LETTERS
week ending
31 MAY 2013
0031-9007=13=110(22)=228701(5) 228701-1 Ó 2013 American Physical Society