The crests (bright) and troughs (dark) of waves spread out after they were produced. The picture applies to both light and sound waves.
Most people are familiar with lasers. But what about a laser made with sound rather than light? A couple of physicists have now created one that they plan to use for measuring imperceivable forces.
Ultrasonic “tractor beam”
Asier Marzo, Bruce Drinkwater, Sriram Subramanian
From acoustic holograms to tractor beams.
Illustration of the acoustic force fields created by the 64 speakers beneath the red object – strong enough to hold or move it.
Asier Marzo, Bruce Drinkwater and Sriram Subramanian
A millimetre-sized object has been levitated and moved around in mid-air using nothing but sound waves.
Don’t fear losing that ball, the waves will bring them back.
You would normally expect objects that float in water to move in the same direction as waves. But now we can force floating objects to move in the opposite direction. This unexpected effect nicknamed a…