I was thinking, why isn’t it possible to use this technology to create levitating objects or vehicles???
Like UFO type flight.
Just attach powerful emitters around the craft.
This article makes me think this might be possible.
F= m*a
If waves possess mass, then it could be used as a means of force.
It can, at least if we squint a bit. There is a clear mathematical relationship with all the various bits involved. Compute the amount of energy required to create the amount of sound to levitate, say, something with the mass of a car.
You'll compute an amount of energy sufficient to destroy any conceivable emitter and any object it is targeted at. My intuitive guess is that you'll actually require an amplitude of sound that isn't sound anymore; there's actually a maximum volume that sound can have, because the bottom of the wave can only go to zero pressure. It can't go past vacuum.
Also, I'd have to think about it a bit more, but I believe it would require the emitter to be separate from the thing being levitated... I think trying to self-levitate with a sound emitter would be the mathematical equivalent of trying to fly by pulling up on your hair.
So don't think full-sized UFOs dapperly zipping about with discreet little "blip blip blip" sounds in the distance... think a train car running underneath a levitating car, with a speaker giving off energy comparable to continuously-exploding bunker-buster bombs, if not nuclear bombs.
Definitely better off with a helicopter.
There is a reason all the things you've seen lifted are little bits of styrofoam and ping pong balls.
[1] Acoustophoretic contactless transport and handling of matter in air https://www.pnas.org/content/110/31/12549
https://en.wikipedia.org/wiki/Sound
https://en.wikipedia.org/wiki/Longitudinal_wave
http://www.people.fas.harvard.edu/~djmorin/waves/longitudina... [pdf]