Saturday, January 4, 2014

Soundpack Joyride

You ever watch some piece of fiction, TV, movie, cartoon, whatever, where someone revs up an amp- or several amps- hooks an electric guitar up, and then unleashes a soundwave that physically throws people backward?

The first thing we should establish today is that there is proof of concept of such a thing. Obviously, not to that extent, but it is possible to not only move objects with sound, but make them float. The process is called, logically enough, acoustic levitation. HowStuffWorks has a detailed overview of the process, and I'm not going to even claim to be able to break down the full process in anything but baby terms. But in short... you've heard of soundwaves, right? Soundwaves are a form of force, if relatively weak. They're a pressure wave. They move air. By sending out a series of such waves, of the proper frequency, aimed and reflected and timed juuuuuuuust right, you can get an object airborne and floating. The key is what's called a standing wave, which is a wave with points that remain stationary, such as a string instrument, or a jump rope such as this one:

The stationary parts of the wave are the parts where you can levitate an object. Scientists have been experimenting with this for some time now; Louis V. King of McGill University seems to be the first to have dealt with the topic as far back as 1934 with his paper "On the Acoustic Radiation Pressure on Spheres". Right now the applications are lacking in the commercial realm- current usefulness is largely industrial, scientific, medical- but with enough time, with enough enhancement, you figure out what you might want to do with something that uses sound to levitate. You've probably come up with about three or four awesome things off the top of your head.

The news over the wires right now is that there's been an evolution in the capability. Up until now, scientists have only been able to lift an item (and at a limit of a couple kilograms; again, soundwaves don't have a lot of lift to them), through pointing all the speakers in one direction. A team at the University of Tokyo has given things a third dimension through having four speakers surrounding an area: in addition to lift, they can now get an object to move, and stop, and move again.

As you can see here:

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