Scientists Figure Out Pendulum Clock Puzzle That Dates Back Centuries

Well, it’s about time!

After more than three centuries, scientists say they have figured out why pendulum clocks hung on the same wall tend to sync up–with one clock’s pendulum swinging to the left just as the other swings right.

The strange phenomenon was first observed in 1665 by Christiaan Huygens (1629-1695), according to LiveScience. No matter how the clocks started, the Dutch scientist noticed that within about 30 minutes their pendulums wound up swinging in precisely opposite directions.

Over the years various explanations were offered, including the idea that the pendulums sync up as a result of tiny air currents they create, AFP reported.

But according to a new paper published on July 23 in the journal Scientific Reports–which builds on earlier research, including a study published in 2002–this is the correct explanation: sound waves generated by the movement of one pendulum travel through the wall to perturb the movement of the other until the pendulums are moving in opposition.

As Dr. Henrique M. Oliveira, a University of Lisbon mathematician and one of the study’s co-authors, told The Huffington Post in an email, “The two clocks interact, giving two ‘kicks,’ one in one direction and another one in the opposite direction… Only when the clocks are at phase opposition the effects of the perturbation cancel” and the pendulums swing in opposite directions.

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Oliveira said he and study co-author Dr. Luis V. Melo (pictured above), a physicist at the university, reached their conclusion after developing a complex mathematical model and then confirming it experimentally with a pair of clocks hung on an aluminum rail.

The finding shows that “very small interactions can add up and in the end synchronize very large systems,” Oliveira said. The same basic principle is seen in other disciplines, he said, —> Read More