Lecturer: Prof. Nir Gov
Affiliation: Department of Chemical Physics
Weizmann Institute of Science
Abstract:
Examples of collective motion exist throughout
biology, from the collective motion of cells
during morphogenesis, wound healing and
cancer, and for animal groups that migrate,
forage and hunt together. We have been
applying physical modeling for such systems, at
the different scales. At the level of animal
groups, we have been studying the collective
load carrying by ants, as they transport food to
the nest. In this system we propose a model
where the decision making at the level of the
single ants is affected by the whole group
through the forces transmitted by the load. The
model for this system is therefore inherently
mean-field in nature, and exhibits a
thermodynamic order-disorder transition. Due
to the mean-field nature, the critical
temperature for the system increases with the
system size, which allows to probe it by simply
changing the load size. These predictions agree
with observations. Another system that we
have been studying is that of flying midges,
that spontaneously form swarms at dask. We
propose that the interactions are due to long-
range acoustic signals, and we end up modeling
midges that attract each other through an
"adaptive-gravity" force. The adaptivity
property, whereby organisms adapt their
sensitivity according to the amplitude of the
external signal, makes this an interesting
variation to regular gravity.