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September 28, 2012 10:32 AM   Subscribe

Synchronizing 2, 3, 5, 9, 16, 24 and 32 metronomes on a moving platform. A brief explanation. Another explanation, with pictures.
posted by griphus (26 comments total) 19 users marked this as a favorite

 
What is this post without a little Ligeti?
I wonder what a performance of Poème symphonique would be like on a skateboard? A REALLY BIG skateboard?
posted by carsonb at 10:41 AM on September 28, 2012 [3 favorites]


Asynchronous tick-tocks followed by synchronous tick-tocks followed by Robert Palmer's "Addicted To Love."

Musicologists are still trying to figure that one out.
posted by griphus at 10:52 AM on September 28, 2012


Very interesting, and fun to watch.
I wonder what would happen if the metronomes were set to different beats, say 90 and 92.
I'd try it, and I do have two metronomes, but one of them is on my iPhone.
(plus I don't have a skateboard)
posted by MtDewd at 10:56 AM on September 28, 2012


I love how they keep fighting to go out of sync again. YOU CAN'T MAKE ME CONFORM! I AM NOT A MACHINE--oh wait, yes I am...
posted by Greg_Ace at 10:59 AM on September 28, 2012 [2 favorites]


the ones with a lot of metronomes remind me of how crowds at sporting events sometimes start clapping for something and for whatever reason spontaneously begin clapping in unison.
posted by TedW at 11:00 AM on September 28, 2012 [1 favorite]


(I should have said that my comment refers to the video in the "A brief explanation" link)
posted by Greg_Ace at 11:01 AM on September 28, 2012


Also, the "32 metronomes" video needs to have Pink Floyd's "The Wall" kick in once they're all in unison.
posted by Greg_Ace at 11:06 AM on September 28, 2012 [1 favorite]


What is this post without a little Ligeti ?

Came in to post this!
posted by victory_laser at 11:12 AM on September 28, 2012


This is almost as satisfying as watching Euler's disk spinning.

In the 24 one it looked like the one at the front left was resisting, but he eventually came around.
posted by Acey at 11:21 AM on September 28, 2012 [5 favorites]


This is almost as satisfying as watching Euler's disk spinning.

Pogs thread is over next floor up, dude.
posted by griphus at 11:25 AM on September 28, 2012


this is why i could never play with metronomes-- they're clearly all of them defective.
posted by twist my arm at 11:44 AM on September 28, 2012 [1 favorite]


These are actually a classic example of systems of Kuramoto Oscillators.

If you try to hook up various oscillators with various natural frequencies, (like 90 and 92), the system will try to snychronise, get close for a while, freak out for a few seconds, and then repeat.
posted by Th_ at 12:10 PM on September 28, 2012 [2 favorites]


I'm playing these all just loudly enough to drive my coworkers insane.
posted by backseatpilot at 12:27 PM on September 28, 2012 [2 favorites]


I'm concerned about all these increasingly militant timekeeping devices.
posted by overeducated_alligator at 12:28 PM on September 28, 2012


I wonder what would happen if the metronomes were set to different beats, say 90 and 92.

I'm pretty sure they would synchronize at some in between frequency. Now if it was 60 and 110.. I'm not sure.. Like, one at f, and the other at 2f should be stable, I think.
posted by Chuckles at 12:36 PM on September 28, 2012


A man with one metronome knows the time. A man with two is never sure.
posted by asterix at 1:15 PM on September 28, 2012 [1 favorite]


Why is it that I can so easily imagine the little head of the metronome smiling as it gets in line? Oh god ...
posted by rudster at 1:24 PM on September 28, 2012


A neat video on the related pedestrian-induced swaying of the London Millennium Bridge as mentioned in the second explanation link.
posted by exogenous at 1:53 PM on September 28, 2012 [3 favorites]


Everyone in the world! Turn on your windshield wipers!!
posted by not_on_display at 2:29 PM on September 28, 2012


I was really rooting for the one pink metronome in the 32 video. She got herself in an opposite pattern and held out against the tide for a long time, but eventually she, too, was subsumed in the mass culture that took hold.

It was really interesting trying to pick out which beat would finally become dominant and then watching it spread to nearby metronomes one by one.
posted by Scattercat at 2:43 PM on September 28, 2012 [2 favorites]


Previously. 100 metronomes.
posted by public at 4:29 PM on September 28, 2012


Strikes me that when you have N oscillators on a movable platform, you don't have a collection of N oscillators, you have N+1 oscillators because the platform will become an oscillator too.

If your initial condition has many unsynchronized oscillators sitting on an unmoving platform, the total momentum of the system will be zero, and so by conservation of momentum, it will always have zero momentum.

In the totally synchronized state, then, the total momentum of the moving parts of the oscillators will always be equal and opposite to the total momentum of the platform plus the non-moving parts of the oscillators, and the ratio of the two velocities of those two components of the system will be equal to the inverse of the ratios of the two masses.

It seems weirdly anti-entropic to me-- in the sense of going from a disordered state to a more ordered state-- for a system with velocities which are initially randomly distributed in magnitude and direction to spontaneously separate itself into two components which have velocities which are always equal in magnitude and always opposite in direction.

In terms of energetics, there are some kind of surprising things, too, and those might help resolve what seems to me to be paradoxically decreasing entropy, but at the moment I'm not sure.
posted by jamjam at 4:49 PM on September 28, 2012


Strikes me that when you have N oscillators on a movable platform, you don't have a collection of N oscillators, you have N+1 oscillators because the platform will become an oscillator too.

If your initial condition has many unsynchronized oscillators sitting on an unmoving platform, the total momentum of the system will be zero, and so by conservation of momentum, it will always have zero momentum.


Very interesting. Now I want to see 32 metronomes on a suspended, frictionless surface.
posted by charlie don't surf at 8:03 PM on September 28, 2012


It seems weirdly anti-entropic to me-- in the sense of going from a disordered state to a more ordered state-- for a system with velocities which are initially randomly distributed in magnitude and direction to spontaneously separate itself into two components which have velocities which are always equal in magnitude and always opposite in direction.

You can impose order on a disordered system if you use energy to do so. In this case, it's the potential energy in the springs in the metronomes winding down.

The net entropy of the system goes up; the potential energy in the springs eventually ends up as thermal energy in the room.
posted by sebastienbailard at 10:31 PM on September 28, 2012


You're saying it's a dissipative system, then, to use language I'm more familiar with.

I thought so, but the hand-wavey explanations in some of the links seemed equally applicable to oscillators such as lossless pendulums on a frictionless movable platform, and if a dissipative system is required, that kind of system would not show this kind of synchronization.
posted by jamjam at 11:48 PM on September 28, 2012


steven strogatz wrote about this in sync!

also btw, re: dissipative systems...
posted by kliuless at 8:54 AM on September 29, 2012


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