Scientists had
already been working on models that can push tiny objects small distances using
light, but a new version of a tractor beam uses sound instead. Researchers
figured out a way to manipulate a tiny physical object using what they call,
acoustic holograms.
The researchers
used a grid of tiny loudspeakers to levitate, rotate, and otherwise manipulate
a tiny ball in mid air. They did this by programming the speakers to send out
high intensity sounds that create a kind of force field around the object.
More
information: