20 April 2012

Art intrinsic to science - pendulums

Beautiful.  From Harvard Natural Sciences Lecture Demonstrations:
Fifteen uncoupled simple pendulums of monotonically increasing lengths dance together to produce visual traveling waves, standing waves, beating, and (seemingly) random motion.

The period of one complete cycle of the dance is 60 seconds. The length of the longest pendulum has been adjusted so that it executes 51 oscillations in this 60 second period. The length of each successive shorter pendulum is carefully adjusted so that it executes one additional oscillation in this period. Thus, the 15th pendulum (shortest) undergoes 65 oscillations.

Our apparatus was built from a design published by Richard Berg [Am J Phys 59(2), 186-187 (1991)] at the University of Maryland. The particular apparatus shown here was built by our own Nils Sorensen.
What it reminds me of is the auto-synchronization of five metronomes, but in that case the metronomes were coupled, at least loosely, by being placed on a movable platform.  The pendulums, as I understand it, are not interacting, but simply demonstrating mathematical relationships.

Via Cynical-C, clusterflock, and Kottke.

Addendum:   Reposted from 2011 to add a link to this related phenomenon, which I don't know how to embed.  Via Reddit.


  1. Superb.

    Reminds me of what I loved about Grateful Dead music - transitions between apparent chaos and beautiful patterns, then back again, all governed by mysterious mathematical patterns that resonate to a pleasing degree in the human mind. Good stuff.

  2. Thank you for sharing that. Absolutely beautiful.

  3. This is the best example I have ever found to explain abiogenesis to other people the principle about the origin of the first life form. People have trouble grasping the nature of how the first organism had came about. How lifeless molecules that were already in existence could create order. How could organization come, seemingly out of nothing? Through science, we continually demonstrate how the physical principles that define our reality subtly create order, where none may have been perceived before. Or “How water molecules create a convection pattern in a pot boiling pot”, as Carl Sagan would say. The pendulums in this video visually create order using the same principles to define reality. If you carefully watch you can pick out the pattern to many things you see in the natural world. The structure of the double helix that appears is something that blows me away. Also several of the other patterns show the way some animals naturally move about in nature, indicating they move upon the least resistible pathway through gravity. You see the snake-like slither, the swagger of a fish body as he makes his way through his underwater world. The world we so seemingly forget about… Seems all to ironic knowing you owe your origins to this world, just as all the rest of life.

  4. Interesting that you mention that the units are not coupled. They probably are, though not intentionally. It's quite hard to ensure that pendulums are independant - long-case clocks kept in the same room often become synchronised because of the tiny movements transmitted by a wooden floor or studwork walls.

    1. Relevant -



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