How do you solve a problem like gravity? According to researchers from the Universities of Bristol and Sussex, with 64 miniature loudspeakers.
Writing for Nature Communications, the physicists have created a device that uses high-pitched, high-intensity sound waves to encase- and control – small objects.
"We all know that sound waves can have a physical effect," said Bruce Drinkwater, Professor of Ultrasonics at the University of Bristol. "But here we have managed to control the sounds to a degree never previously achieved."
The device comes in three varieties. One creates an acoustic field which looks like a human hand or a pair of tweezers. Another forms a three-dimensional “cage” around the object, while a third works as a kind of vortex, pulling the object toward the device quicker than the Millennium Falcon to the Death Star.
"In our device we manipulate objects in mid-air and seemingly defy gravity," said Sriram Subramanian, Professor of Informatics at the University of Sussex. "Here we individually control dozens of loudspeakers to tell us an optimal solution to generate an acoustic hologram that can manipulate multiple objects in real-time without contact."
The team sees a wide range of uses for the technology, once perfected. It could, for example, be used in the assembly process of particularly delicate objects. Using tractor beams, workers could handle items without actual physical contact.
NASA has also expressed interest in a magnetic tractor beam which it could use to manipulate small, CubeSat satellites in Earth orbit.
"It was an incredible experience the first time we saw the object held in place by the tractor beam," said Asier Marzo, the study’s lead author. "All my hard work has paid off, it’s brilliant."
We’re still a long way from being able to sonically transport anything larger than a pea. But it’s certainly an impressive proof of concept.