Media Hunt #1: Emergent Order on a Vibrating Plate

The below video, which I found on YouTube, is an example of what is known as a Chladni plate.  A metal plate is covered with salt, set up on top of a loudspeaker, and vibrated at various frequencies.  These vibrations cause the grains of salt to organize into patterns.  The patterns arise because salt gathers at the nodes of the standing waves that form in the metal plate at resonant frequencies.  Notice that at higher frequencies the lines of salt that form are closer together because the standing waves have a shorter wavelength so the nodes are closer together.  This is a variation of an experiment done famously by German physicist Ernst Chladni in the 1780s.  He used a violin bow instead of a speaker and sand instead of salt but the concept was the same.  Chladni was actually repeating the experiment of Robert Hooke, who had done the same thing a century earlier using flour on a glass plate, but for some reason it was Chladni’s name that stuck.

As a word of caution, I would suggest lowering the volume on your computer before playing this video.  The sounds used to vibrate the plate, especially the high-pitched ones, are a little annoying.

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