Web Exclusives: Alumni Spotlight
mathematician Steven Strogatz '80 has been at the forefront
of the movement to turn "sync" into the next hot
by Dede Hatch
Strogatz '80 pioneers new science of sync
Gaze out at a suburban lawn at dusk, and the fireflies you see
will light up haphazardly: As soon as you see a flash out of one
corner of your eye, it disappears and another one appears somewhere
Like most of the estimated 2,000 species of fireflies around the
world, they don't flash in unison. But a handful of firefly species
do, including Photinus carolinus, which lives near an abandoned
cluster of cabins called Elkmont, on the Tennessee side of the Great
Smoky Mountains National Park.
Now, only a decade after scientists first took note of them, these
unusual insects have become the most popular symbol of an emerging
field called "synchrony," or, more commonly, "sync."
And Steven Strogatz '80, Cornell University mathematician, has been
at the forefront of the movement to turn "sync" into the
next hot scientific discipline.
Synchrony appears throughout the natural world. It is most obvious
in schools of fish turning suddenly in unison, or birds wheeling
through the sky in formation, or in the perfectly timed chirping
of crickets. At Elkmont, for two to three weeks every June, groupings
of hundreds of male fireflies flash together four to eight times,
with a brief pause between flashes. Then the flashing stops for
six to 10 seconds before the cycle begins once again. The display
starts at dusk and lasts for hours.
"It's like a wave as it goes up the hill," says Rebecca
J. Nichols, a National Park Service entomologist. "Once the
first one starts, they all follow."
Regular users of the cabins had noticed, and enjoyed, the phenomenon
for years. But until the early 1990s, scientists had believed that
the only truly synchronous fireflies were species native to Southeast
Asia that flashed in unison while resting on riverbanks.
That changed in 1992, when Elkmont regular Lynn Faust saw an article
about Strogatz's work on synchrony. Strogatz was studying synchronous
patterns in nature, and the article mentioned fireflies but
not those at Elkmont. So Faust described their behavior to him.
Strogatz put Faust in touch with Jonathan Copeland, a behavioral
neurophysiologist at Georgia Southern University who specializes
in fireflies. Along with Andrew Moiseff of the University of Connecticut,
Copeland had studied synchronous fireflies in Southeast Asia the
Since then, Copeland and Moiseff have returned annually to Elkmont,
hoping to understand both the how and the why of synchronous flashing.
The how, as best they understand it, is that the males synchronize
by watching other males. The researchers demonstrated this by experimenting
with "artificial males" computer-generated flashes
and by setting up pairs of fireflies in a chamber. When blocked
by an opaque barrier, the paired insects flashed independently,
but as soon as the barrier was removed, they flashed in sync with
As for why, several theories have been suggested over the years.
The Leading, though not yet proven, explanation is that females
are likeliest to mate with males that flash earliest. The inevitable
result of this fierce competition, the theory goes, is that every
firefly ends up flashing simultaneously.
As a mathematician, Strogatz was less interested in the mechanics
than in the fact that they behaved synchronously at all.
For him, the firefly served as the perfect poster child for sync.
When Strogatz published Sync: The Emerging Science of Spontaneous
Order (Hyperion) earlier this year, he put fireflies on the cover.
Though the book is filled with difficult mathematics, it is designed
to introduce a lay audience to the many systems that exhibit spontaneous
"It's a theme you see a lot in biology," Strogatz says,
and not just in birds and fish and crickets. Heart cells beat in
synchrony; women who live or work together may find their menstrual
cycles coinciding due to subtle chemical communications; and certain
kinds of cicadas emerge in unison every 17 years.
Odder still is the synchronous behavior often seen in inanimate
systems: lasers, electrical grids, quantum mechanics, flows of automobile
"What I find striking about these phenomena is that they
illustrate the theme of self-organization," he says. "There's
nothing in the environment no lightning bolt, no external
cause that tells them to. It emerges automatically."
The fact that we see only one side of the moon as it circles the
Earth is a form of sync, stemming from the stabilizing tidal forces
exerted by the Earth on the moon. So is the phenomenon, discovered
accidentally in 1665, that two clocks in the same room may synchronize
their pendulum swings as they react to each other's vibrations.
"Mindless things can synchronize by the millions," Strogatz
says. "It doesn't take a mind, or even have to be alive. Simple
laws could lead to groups being in sync. It's counterintuitive,
because the usual thinking was that things get more disordered over
Sync is merely the most recent multidisciplinary theory to create
a public stir, following the popularization of chaos and complexity
theory in the 1970s and 1980s. But while many researchers are looking
at aspects of sync individually, it has taken time for a unified
discipline of "sync" to jell.
One reason may be the complicated mathematics that describes synchronous
behavior. Another reason may be the intense specialization of much
contemporary scientific research, which tends to discourage interdisciplinary
John Hopfield, a professor of molecular biology at Princeton who
once studied similarities between neurons and earthquakes, said
that "synchrony is not, in my opinion, likely to become a field
of science, just as calculus is not a field of science. But ...
the better it is understood mathematically, the more likely we are
to be able to understand, control, and utilize synchronization effects
in the real-world systems of science and engineering."
And Philip J. Holmes, a professor of mechanical and aerospace
engineering at Princeton who calls himself "an old-school disciplinarian,"
adds that while multidisciplinary work can be "useful and illuminating,
it does not replace the hard, detailed, often tedious science that
still has to be done, often using the usual disciplinary tools."
Yet even Holmes notes that he and his colleagues are using applied
mathematics to understand some aspects of synchronized pulses in
a part of the brain stem that helps oversee cognitive processing.
By focusing on complex and far-flung interactions, sync may help
scientists make progress on such conundrums as the survival of stressed
ecosystems, the evolution of global climate change, and the operation
of the international economy. These questions, he suggests, may
be impervious to science's most familiar method of analysis--looking
at ever-smaller units.
Strogatz himself is beginning to apply his background in mathematics
and sync to explore the mysteries of cancer. "Bad genes explain
some cases" of cancer, he said, "but others are not explainable,
and they seem to have something to do with the choreography of chemical
reactions going wrong. So I want to be helpful, but I'm not sure
By Louis Jacobson '92
Louis Jacobson, a staff correspondent at National Journal magazine
in Washington, writes frequently about science. A different version
of this article appeared in the Washington Post.