Revealing a 350 Year Old Question: Why Pendulum Clocks Swing Together

Close to 350 years ago, a Dutch inventor and scientist by the name of Christiaan Huygens observed that two pendulum clocks hanging from the same wall would synchronise their swing after a certain amount of time. And following this moment in time, the whole phenomenon has caused scientific head-scratching the world over for centuries after. However, still, after all this time, no consensus had been reached… until now.

A study in the journal Scientific Reports has offered some much-needed clarification that could provide people with the final answer they’ve been longing for. What is it? Well, scientistshave claimed that the pendulums transfer energy to one another via the medium of sound pulses.

Two Portuguese scientists put forward the idea that these pulses might move from clock to clock, upsetting the swing of the pendulums and ultimately causing them to swing in harmony.

They established an intricate mathematical model before they carried out their experiments using a pair of clocks that had both been attached to a rail after securely fixing them to a wall. Following their theoretical predictions, it was revealed that the simulation matched their calculations.

“We could verify that the energy transfer is through a sound pulse,” said co-author Luis Melo, from Lisbon University’s physics department.

“This not only solves an old, fundamental problem, but it also boosts understanding of other types of oscillator”, Melo added.

If this has satisfied your thirst for horological knowledge, why not find out some more information of the horological kind in our feature on how to spot fake antique pocket watches

Image: Paul Hood under Creative Commons.


This article was updated on 20 June 2017.