Acoustic levitation [Resources]

Magicians have long made things appear to hover without any visible means of support. For some reason, engineers delight in trying to turn this particular illusion into reality, and we're no exception at IEEE Spectrum. Back in 2014, for example, W. Wayt Gibbs wrote for us about how to make a miniature disco ball levitate using the power of electromagnetism. But that system works only for objects that can have a magnet attached. So, when I saw a kit promising to make any kind of small object float, even drops of liquid, I knew I had to have it.