YSM Issue 87.4

Swarms
by zachary miller
art by christopher paolini
of Physics at Gettysburg College, recorded
many swarms of midges of various sizes.
They measured characteristic properties of
these swarms, including the average distance
from one midge to another and the average
velocity of each midge. By plotting each
property against swarm size, they could
better understand how a group of midges
becomes a swarm. They found that every
property they examined leveled off rapidly,
having a consistent value for large swarms
of any size. Once the number of midges
reaches a sort of critical mass, a swarm
forms, and its characteristics remain similar
no matter how many more flies are added.
Somewhat surprisingly, in each case this
leveling off occurred for swarms of less
than ten individuals. Thus, they conclude, it
only takes ten midges to behave like a swarm
of many more.
The surprises, uncertainties, and hazy
definitions all reflect the novelty of swarm
science. Although humans have observed
and interacted with herds, flocks, and
swarms for millennia, only recently have
these phenomena—and the differences
between them—become accessible to
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scientists. Ouellette believes that tools for
studying swarms have allowed the field to
grow rapidly in recent years. These tools
include inexpensive and easily accessible
digital imaging technologies for recording
swarming behaviors, and computer vision
programs that allow researchers to track
individuals within a swarm.
The Appeal of Swarms
Ouellette himself became interested in
swarming after developing computer vision
tools for the study of fluid mechanics.
Following particles in a swirling pool isn’t
so different from tracking midges flying
IMAGE COURTESY OF NICHOLAS OUELLETTE
The reconstructed flight paths of midges
in a single swarm. Each color represents a
different individual.
in a cloud. The parallels made it easy to
dip into biology. His progression isn’t
uncommon; Ouellette says that thanks to
technological advances, “physicists and
engineers have a lot of opportunities to look
at classically biological problems.” The mix
of backgrounds among swarm scientists
and the fertile intellectual ground they are
exploring make for a heady combination.
The explosion of interest among researchers
is mirrored by the popularity of books like
The Perfect Swarm by Len Fisher or Peter
Miller’s The Smart Swarm. “Any time you have
a problem with a real interdisciplinary focus,
scientists get excited,” Ouellette says.
Studying swarms isn’t only an intellectual
exercise, though. While the field is still
very young and focused on exploring
basic concepts, according to Ouellette,
the applications for its findings are
already exciting interest. The relevance of
swarms for robotics is possibly most clear.
Borrowing from the behavior of such
simple animals as midges, engineers could
build artificial swarms that exhibit complex
behaviors without complex programming.
Indeed, a number of researchers have
October 2014
Yale Scientific Magazine
13