Researchers Confirm 25-Year-Old TheoryThat Groups Seek Unison
May 31, 2002-- Unison is the
harmony that nature loves best.
crickets chirp, or fireflies flash their lights, or a frenzied audience
of pre-teen girls applauds the latest boy band, the action starts
as a collection of individuals but ends as a group chirping,
flashing or clapping acting together.
interactions among individuals lead to group dynamics known as synchrony.
A theory explaining how synchronization emerges was developed 25
years ago but never validated in a laboratory setting. Until now.
todays [May 31] issue of the journal Science, three chemical
engineers at the University of Virginia describe the results of
experiments they designed to confirm the theory of synchronization
that scholars Arthur Winfree and Yoshiki Kuramoto conceived in the
used chemistry as a platform to study this phenomenon, which occurs
in many different scientific fields, including biology, physics
and ecology," said Jack Hudson, the Wills Johnson Professor
of Chemical Engineering at U.Va.s School of Engineering and
Applied Science, who heads the research team.
researchers -- including chemical engineering post-doc Istvan Kiss
and doctoral candidate Yumei Zhai studied the onset of synchrony
by observing a series of electrochemical reactions. They plunged
the tips of 64 wires made of nickel into a beaker of sulfuric acid.
Then they plugged the other ends into a power source, turned on
the power and recorded the results.
they found was that, because of interactions among the 64 electrodes,
a group of the metal tips began reacting simultaneously. And as
the interactions grew stronger, the remaining points joined in as
well. (Imagine a fight on the playground attracting first a cluster
of children and then everyone, including the principal, once it
becomes clear what is going on.)
the lab, the pace of the chemical reaction on each metal tip was
illustrated by a wavy, or oscillating, line on an oscilloscope.
Initially, the 64 waves differed slightly in their length, depth
and height. But over time the experiments ran for about three
minutes -- the waves began to coincide. Synchrony had been achieved.
used a quantitative measure to determine how much order there is
in a group of reactions in a system and to show how the strength
of interactions influences this order," Hudson said.
their work, the U.Va. researchers found that Winfree and Kuramotos
theory predicting the onset of synchronization in oscillators covers
more ground than the theorists had imagined. Varying the experiments,
the U.Va. team found that the theory holds true not only for regular
reactions, but also for irregular, so-called chaotic reactions.
believes his teams work will have an impact on research in
many different fields and in the development of more powerful lasers
and microwaves for communications.
Charlotte Crystal, (434) 924-6858