Man takes five metronomes ticking randomly. Puts them on a slightly mobile plank held on two tin cans. Metronomes run in sync. Magic. Now I'd like to see someone really mess up György Ligeti's Poème Symphonique For 100 Metronomes... (via Kottke)
Posted by Tom Whitwell.
This is probably a good metaphor for musicians learning to play together.
This seems to be 'entrainment' in action - I really thought that was a myth. I spent 3 months adjusting 2 mechanical alarm clocks, trying to get them to entrain. It didn't happen. In this case the plank moves and that's what the difference is. Maybe it really does become a 'complex pendulum'?
Huygens had two pendulum clocks he had built on the same wall and no matter what he did, they would always sync up. Way I heard it, he was sure there was some property of pendulums that caused them to sync up, but he could never put his finger on why it only worked with his clocks on the wall.
Now we can explain it through sympathetic resonance (essentially), and this is a very good demonstration.
This is entropy, no? The energy created by the any of the metronome's "weak" action (against the predominant energy wave) is transferred away via the wood on the cans? This progressive escape of energy (it's regenerated every stroke because the weight of the metronome is constant).
Wait, I have NO idea what I'm talking about.....
I'd really be interested in reading a physics explanation of this.
From a Physics Grad Student I know: "well, I don't know much about how metronomes work, but it seems like you can just tap them to change the frequency. So, with this in mind, you have like 5 oscillators(adjustable) all connected to the board. So they make the center of mass of the whole board metronome system oscillate. And when center of mass oscillates its acts like a driving force on the metronomes so it changes their frequency, which then changes the center of mass frequency again. It looks like it just does this until it finds its resonance frequency. Its kinda interesting. Its like a damped driven harmonic oscillator, but the driving force is affected by the system it self. "
This is indeed cool, but the metronomes are not ticking 'randomly'. They are all set at the same tempo, starting at slightly different 'random' times admittedly. If they were set randomly (at different tempos), you obviously would not get the same effect. As it is, it only requires a small shift to nudge the tempos so that they are all in synch.
By the way, would the tempo be slower when on a movable surface (such as the one shown)?
Interestingly, it sounds as though the metronomes are changing sync slightly even before he puts them on the board. No idea why. Also, on the plank, they seem to be going in and out of sync in some kind of cycle.