CMSP Seminar @ICTP on Thursday 12 December at 11 am - Asja JELIC

[CM Section]

Condensed Matter and Statistical Physics Seminar

Thursday 12 December at 11 a.m.
Luigi Stasi Seminar Room first floor, Leonardo building

Speaker: Asja JELIC (ICTP, CMSP Section, Trieste)

Title: Propagation of information in turning flocks of starlings

Abstract:
Animal groups on the move are a paradigmatic example of collective
behavior in social species in which the tools of statistical physics can
be fruitfully used. I will present an experimental and theoretical study
of spontaneous rapid collective turns in natural flocks of starlings in
which we find a sound-like propagation of the turning decision across the
flock with no damping of information. This is in contrast with standard
theories of collective animal behavior based on alignment, which
predict a much slower, diffusive spread of information. We propose
a novel theory for propagation of orientation in flocks whose
key ingredient is the existence of a conserved spin current generated by
the gauge symmetry of the system. Moreover, our analysis reveals
that spontaneous collective turns are triggered by persistent
localized fluctuations in the travel direction of some individuals in
the flock. Two crucial ingredients which enhance the effect of such
noise leading to collective changes of state are: the non-symmetric
nature of interaction between individuals and the presence of
heterogeneities in the topology of the interaction network.