Using a simple set of loudspeakers, scientists have figured out a way to levitate and rotate objects in midair. If perfected, this “sonic tractor beam” could find uses ranging from treating kidney stones to creating artificial gravity on the International Space Station.
Scientists have used sound to levitate objects before. That feat isn't surprising, as sound is a wave of pressure strong enough to move your eardrum. However, instead of audible sound, sonic levitation utilizes higher ultrasonic frequencies that are beyond the range of human hearing. When blared from loudspeakers in the right configuration, these sound waves can combine to form a sonic scaffolding called an interference pattern—a sort of a force field that can hold a small object aloft.
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