Odd Sympathy

Laid up in bed during a brief illness and idly watching two clocks mounted in one case, Huygens noticed something strange: No matter how the pendulums started out, eventually they always ended up swinging in exactly opposite directions. Huygens wondered whether this odd sympathy might solve the longitude problem. Perhaps, he thought, two such clocks could regulate each other. If one got dirty, for instance, and started running slow, the influence of the other clock would lessen this effect. Ironically, Huygens's discovery that the pendulums influenced each other in this way led the Royal Society to lose faith in pendulum clocks as a solution to the longitude problem. At one of their meetings at the time, it was recorded that "occasion was taken here by some of the members to doubt the exactness of the motion of these watches at sea, since so slight and almost insensible motion was able to cause an alteration in their going."


To explain why the pendulums move in opposite directions, the team set up a system of equations that took into account the pertinent properties of the system, including the weights of the various components and friction. The structure of the equations made it clear that friction is the cause of the antisynchronized motion. As Huygens originally postulated, the swinging of the pendulums exerts small forces on the supporting beam. If the pendulums are moving in the same direction, together they nudge the beam the other way, giving rise to frictional forces that naturally put a damper on this kind of motion. If the pendulums are moving in opposite directions, however, the forces they exert on the beam cancel each other, and the beam doesn't move. So over time, antisynchronized motion wins out over synchronized motion.

According to Steven Strogatz, an applied mathematician at Cornell University, Huygens's discovery was the first-ever observation of what physicists call coupled oscillation—at least in inanimate objects. In the 20th century, coupled oscillators took on great practical importance because of two discoveries: lasers, in which different atoms give off light waves that all oscillate in unison, and superconductors, in which pairs of electrons oscillate in synchrony, allowing electricity to flow with almost no resistance. Coupled oscillators are even more ubiquitous in nature, showing up, for example, in the synchronized flashing of fireflies and chirping of crickets, and in the pacemaker cells that regulate heartbeats. "The theme of synchronization between coupled oscillators is one of the most pervasive in nature," Strogatz says.


Mathematician Christiaan Huygens, inventor of the pendulum clock found that two clocks on the same wall will invariably come into counter-synchronization with one another. This is because of thermodynamics and their connection via the support beam in the wall.

Folksonomies: physics thermodynamics oscillation

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Pendulum clock (0.958397): dbpedia | freebase
Christiaan Huygens (0.809289): dbpedia | freebase | yago
Pendulum (0.641929): dbpedia | freebase
Clock (0.597075): dbpedia | freebase | opencyc
John Harrison (0.561746): dbpedia | freebase | yago
Escapement (0.435009): dbpedia | freebase
Odd sympathy (0.412736): dbpedia | freebase
Horology (0.394425): dbpedia | freebase

 Huygens's Clocks Revisited
Periodicals>Magazine Article:  Klarreich, Erica (07/2002), Huygens's Clocks Revisited, American Scientist, July-August 2002, Retrieved on 2013-07-30
  • Source Material [www.americanscientist.org]
  • Folksonomies: physics