Researchers May Have Solved One Mystery After 350 Years

Christiaan Huygens, 'Dutch scientist, mathematician and inventor-of-all-trades', invented the pendulum clock and also developed the first balance spring watches. Yet, he noticed a strange phenomenon one day in 1665. It was a mystery that remained unsolved for 350 years, according to washingtonpost.

Huygens noticed a puzzle in the pendulums of two clocks that were attached to the same beam in his house. The clocks synchronized their swings and oscillated in "perfect opposition to one another". Huygens was fascinated by the peculiar riddle and so forgot that he had "indisposition". He climbed on the beams to stop and restart the clocks at different times. But after an interval, the pendulums went back to their "synchronized dance".

Huygens could not figure out why, nor could the entire scientific community for 350 years.

Today, a couple of Portuguese physicists claim to have found the key to the puzzle.

Last week, they published a study in 'Scientific Reports'. They explained that small pulses created by the ticking clocks course through the connecting wood and slowly make the pendulums get into their synchronized movement.

The scientists recreated Huygens' old experiment with two clocks attached to an aluminum beam. They made them tick and measured each swing of their pendulums with high-precision sensors. After a few days, they found that the swings got into the same kind of movements, like Huygens' clocks.

"When the pendulum swings one way, it turns a gear in the clock's interior, which in turn drops the weight that pulls the second hand around the clock's face. The gear catches, and then the pendulum swings back the other way, setting the mechanism in motion once more. The classic "tick-tock" of a clock is the sound of the gear locking and unlocking as the pendulum swings," according to washingtonpost.

Henrique M. Oliveira, a mathematician at the University of Lisbon and one of the study's co-authors, said that it's due to the sound pulses that flow through the connecting beam, acting as a tiny "kick" that "almost imperceptibly alters the pendulums' swings". Over hours, the little kicks bring the pendulums closer into synchronisation. At "phase opposition" or reaching opposite points of their swing at the same time, both kicks cancel each other out, and they get "stuck in synchrony".

The energy is transferred by the sound from the ticking clocks, causing the pendulums to 'communicate' and nudge each other until their swing matches, according to dailymail.

Another study published in the Proceedings of the Royal Society in 2002 had also suggested that "spontaneous synchronization" was due to the tiny movements on the platform. However, Oliveira and his co-authors explain that their models simulate the Huygens model that was set up 350 years ago.