Ikeguchi Laboratories has posted one of the most fantastic “physics in action” videos I’ve seen in a long time:
The concept is simple — 32 metronomes on a table, all set to the same tempo, but started at slightly different times. But here’s the fun bit — although they begin “out of phase“, after about 2 minutes, they all lock onto the same phase and synchronize! (Well, almost all — there’s a rebel on the far right that takes an extra minute to get with the program).
So what’s going on? The key is that the metronomes are not on a solid table, but instead are on a slightly flexible platform hanging from a string. Thus, as a metronome’s pendulum rod changes direction, it imparts a small force to the platform, which leads to small motions in the platform. The moving platform then gives small nudges back to the metronomes. These forces will tend to push the other metronomes to speed up or slow down to match the timing of the original metronome, bringing the metronomes “in phase”.
Now the really fun bit (for me at least), was watching exactly how this played out in practice. If you watch the ...