The crests (bright) and troughs (dark) of waves spread out after they were produced. The picture applies to both light and sound waves.
Titima Ongkantong
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
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
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…