Disorder to nudge order out of chaos.

Introducing random variability into certain types of systems can help tame their otherwise chaotic behavior. It's a little like adding noise to an audio recording to turn grossly distorted sound into a discernible melody.

This surprising result comes out of computer simulations performed by physicists William L. Ditto of the Georgia Institute of Technology in Atlanta, Yuri Braiman, now at Emory University in Atlanta, and John F. Lindner of the College of Wooster in Ohio. They report their findings in the Nov. 30 Nature.

The researchers studied the behavior of a chain of coupled oscillators, which can be imagined as a row of pendulums, each loosely connected to its neighbors. A motor operating at a given frequency drives all of the pendulums to oscillate, even as friction damps their motion.

Under such conditions, depending on its length, a single pendulum can swing back and forth, settle into an over-the-top whirling motion in which it completes one revolution for each cycle of the driving frequency, or display an irregular pattern of back-and-forth swings interrupted sporadically by over-the-top rotations.

Starting with a chain of identical pendulums, the researchers selected a pendulum length that resulted in chaotic motion, with no coordination among the linked pendulums. They then tried a chain in which the pendulum lengths varied by as much as 20 percent from that in the initial, chaotic array.

"We expected that we would get even more disorder and even more turbulent behavior, but what we got was organized behavior patterns coming out of the system," Ditto says. "The diversity, or disorder, provided a mechanism by which the system could organize itself."

Ultimately, this finding could lead to methods for improving the performance of electronic circuits and devices by exploiting variations among their components.