American Scientist | “In 1665, the great Dutch scientist Christiaan Huygens, inventor of the pendulum clock, wrote to the Royal Society of London to tell them of his discovery of an “odd kind of sympathy” between the pendulums of two clocks hung together. This effect remained a mystery for three and a half centuries, but the Royal Society has now published an explanation of the curious interaction Huygens observed, the result of a study done at the Georgia Institute of Technology…

“According to Steven Strogatz, an applied mathematician at Cornell University, Huygens’s discovery was the first-ever observation of what physicists call coupled oscillation—at least in inanimate objects. In the 20th century, coupled oscillators took on great practical importance because of two discoveries: lasers, in which different atoms give off light waves that all oscillate in unison, and superconductors, in which pairs of electrons oscillate in synchrony, allowing electricity to flow with almost no resistance. Coupled oscillators are even more ubiquitous in nature, showing up, for example, in the synchronized flashing of fireflies and chirping of crickets, and in the pacemaker cells that regulate heartbeats. “The theme of synchronization between coupled oscillators is one of the most pervasive in nature,” Strogatz says.

The Georgia Tech team is now trying to extend its mathematical analysis to formulate a single law that would apply to all coupled oscillators and predict under what conditions they will become synchronized or antisynchronized. “It looks as if there is a mathematical principle that would be equally valid in all these cases,” Wiesenfeld says. “I’m pretty sure we wouldn’t have stumbled across it if we hadn’t had the experience of looking at the problem of Huygens’s clocks.”—Erica Klarreich