It’s been more than 350 years since the Dutch physicist Christiaan Huygens, the well-known inventor of the pendulum clock, observed that no matter how his oscillating clocks started, in less than 30 minutes they would at all times end up swinging the opposite direction to each other if attached on the same beam. The scrutiny, made in 1665 while Huygens was sick in bed with nothing else to look at, gave rise to the expression, "an odd kind of sympathy", and several groups of scientists and mathematicians have tried to clarify it ever since. But a group of scientists from Portugal say they’ve cracked the mystery, attributing the mysterious synchronization to the minute forces produced by sound pulses. Back in the 17th century, Huygens suggested that the syncing - or 'anti-syncing’ - action was accomplished through the sharing of air currents between the two pendulums. Experiments soon negated this theory, and Huygens instead suggested that the sympathetic motion of pendulums was down to the nearly unnoticeable movement in the beam from which they were both suspended.
Since then, researchers have been experimenting with two pendulum clocks hanging from the same beam, and while the deduction was that forces applied on this portable beam were producing the syncing action, no one could settle on how this actually works. But what about if you remove the supporting beam out of the equation totally? Oliveira and his associate Luís V. Melo developed a mathematical model to work with an experiment for which they attached an aluminum optical rail to a wall, and attached two pendulum clocks to to it, 230 millimetres apart. According to Rina Marie Doctor at Tech Times, they said this is the minimum possible distance that the clocks can be from one another without touching.
By means of these perfectly strung pendulums, Oliveira and Melo calculated that the speed of their swings resembled to the cycles of the sound pulses they created, which moved through the wall from clock to clock. Melo told the AFP "We could ... verify that the energy transfer is through a sound pulse,"
The outcomes were issued in the journal Scientific Reports. The team says this isn’t just a clarification for a centuries-old mystery - understanding how "very minor interactions can add up and in the end synchronize big systems" can have vast implications in everything from economics and electronics to the biology of how cells sync up to create a heartbeat, Oliveira said. And Huygens would be proud to know his development - which was reflected as the world's most precise timekeeper for over 270 years - is ultimately back in the spotlight.