Scientists have developed a “sonic tractor beam” capable of manipulating objects in mid-air. They say it could be used for many applications from treating kidney stones to creating artificial gravity in space.
They used simple loudspeakers and an algorithm that builds interference patterns by adjusting the precise synchronisation, or “phases,” of the waves leaving the various speakers.
Some waves are combined to reinforce one another in some places and others cancel each other out in other places, creating a complex 3D pattern of high and low pressure regions, which the authors of the study, published in Science, call an “acoustic hologram”.