Tractor Beam

[elementcollector1]

Hear me out here, because I feel like this shouldn't work but I don't know why.

Here are the two pieces of knowledge I base this off of:

 

-The concept of acoustic levitation is that a standing wave of sound produces enough force to lift an object in midair and hold it.

-If one takes a sufficiently thick piece of paper or thin sheet metal, folds it in half, places an object between the two parts of the fold and attempts to make the angle of the fold more acute, the object is drawn back toward them until it pops out of the wedge.

 

Therefore, if one was to make a cone of sound sufficiently powerful (whether that entails higher frequency, volume, or both), point it at an object so the object is just barely within the confines of the cone, and narrow the angle, wouldn't the object move towards them?

[fiveworlds]

Optical(light)http://en.wikipedia.org/wiki/Optical_tweezers and acoustic tweezers(sound) http://en.wikipedia.org/wiki/Acoustic_tweezers

 

 

 

Edited August 4, 2014 by fiveworlds

[elementcollector1]

Yes, I'm already aware of the microscale experiments, but they work a bit differently. I'm talking macroscale - upwards of a pound, if at all possible. I found this upon further research:

http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.112.174302

Hopefully, with the cone of sound, this is possible with non-triangular objects.

[fiveworlds]

Non-macroscale but non-triangular. But I have never seen anything upwards of a pound.

 

Edited August 4, 2014 by fiveworlds

[elementcollector1]

Huh, I wonder how that works.

According to Wikipedia, most acoustic levitation setups nowadays can only manage a few kilograms, though there is no known limit.

Guess I'll have to experiment when I get the chance, then.

[elementcollector1]

Is there any way to create a focused beam of sound - either a flat wave or a phaser - with a simple setup?