One's mind may recall the pyramids' potential methods of construction, but again, who could produce at that time such an intense sonowave? Rather impossible. But again……
Su Zhao and Jorg Wallaschek wrote A standing wave acoustic levitation system for large planar objects . In this book they discuss an acoustic levitation system which can levitate planar objects that are much larger than the wavelength of the applied acoustic wave.
A sound radiator in conjunction with the levitated planar object emits a standing wave field. Although these forces are normally weak, they can become very powerful when using high intensity waves due to nonlinear characteristics. Rayleigh1 first studied nonlinear acoustics in 1902 as an acoustic counterpart of electromagnetic waves.
Reference 1 outlines the Matrix Method to simulate acoustic levitators. Using an ultrasonic transducer and reflector. See Figure 1.
Scientists at Argonne National Labs used this technique in 2012. Check out this video.
The University of Tokyo, Nagoya Institute of Technology has a good overview of Three-Dimensional Mid-Air Acoustic Manipulation from 2013 .
Much progress in this technique was made by the team of researchers at the University of Sao Paulo in Brazil1 who have developed a new device for levitation that will suspend a tiny object with far more control than ever before. Prior to this test, sonolevitation efforts needed a very precise setup where the sound source and reflector were at fixed resonant distances. This time researchers built a “non-resonant” device for levitation which did not require a fixed separation distance between the source and reflector. See Figure 2
Now larger devices may be built using this technique such as those that can handle hazardous materials or chemically-sensitive pharmaceuticals or maybe even some new high tech toys.
What other uses could you think of for this technique?
- Matrix Method for Acoustic Levitation Simulation, Andrade, Perez, Buiochi, Adamowski, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency control, Vol. 58, No. 8, August 2011