Huygens was inspired by investigations of pendulums by Galileo. Galileo discovered the key property that makes pendulums useful as timekeepers which was isochronism; it means that the period of swing of a pendulum is approximately the same for different sized swings.
Scientists of the University of Lisbon in Portugal think they have solved the centuries-old mystery. In a paper published this week in the journal Scientific Reports, the authors say the answer lies in sound waves.
They tried different beam materials and conditions and could only get connecter when the beam was made of a very good conductor, the clocks were close, and the frequencies were close enough.
The team found that a transfer of energy occurs from the sounds of the indicating clocks, causing the two pendulums to swing in synchrony.
The authors write that the coupling is obtained through the exchange of sound pulses between the clocks circulated through the support.
When one clock receives the kick, the effect circulates in the wall slightly disturbing the second clock. In this model each clock transmits once per cycle a sound pulse that is translated in a pendulum speed change.
✍Examrace Team at Aug 21, 2021