"This is What Happens When You Run Water Through a 24hz Sine Wave"<p>I'm not sure this is the best title. "What happens when you wiggle a hose at a frequency close to a camera's frame rate and then film the water coming out of it" might be better.<p>At the most basic level, this is just the game you used to play with a hose when you were a kid by waving the end and producing ribbons of water in the air. The video just added a camera trick to photograph the ribbon in the same place during each oscillation appearing to freeze it in place.<p>Initially I thought this was going to be much cooler, actually using the speaker to move the air through which the water was travelling to produce an effect. I was hoping for an awesome standing wave demo or something.
Petapixel[0] has a better explanation. It is an illusion created by the synchronized frame rate and oscillation. They have used the same trick with a strobe light for live effects.<p>[0] <a href="http://www.petapixel.com/2012/04/24/sound-and-frame-rates-used-to-make-water-travel-backwards/" rel="nofollow">http://www.petapixel.com/2012/04/24/sound-and-frame-rates-us...</a>
This blew my mind even more because the water looks completely frozen: <a href="http://www.youtube.com/watch?v=mODqQvlrgIQ" rel="nofollow">http://www.youtube.com/watch?v=mODqQvlrgIQ</a><p>I'm still amazed that the water comes out so uniformly.
I bet this would work much better with glycerin or glycerin/water mixtures. Water has a low viscosity, meaning it's relatively easy to induce turbulence. And turbulence, while not exactly chaotic, is somewhat random and nonperiodic.
I feel like there's some information theoretic approach which could be leveraged here, and maybe in similar systems - ie. just from the video we can work out<p>- The difference in video frame rate vs sound frequency based on the period of the wave<p>- Maybe the structure of the wave itself based on the waveform, although maybe not.
A <i>much</i> more interesting effect is putting water and cornstarch on a woofer connected to an oscillator [1]. No special camera tricks required!<p>[1] <a href="http://www.youtube.com/watch?v=3zoTKXXNQIU" rel="nofollow">http://www.youtube.com/watch?v=3zoTKXXNQIU</a>