British physicists have created the first full-fledged "levitator" - a device capable of lifting and holding matter in the air - using peculiar acoustically analogs of holograms.
Scientists from Britain have created the first prototype of a sonic "tractor beam" from science fiction films, capable of capturing, lifting and moving objects of arbitrary shape and high enough mass in the air, according to an article published in the journal Nature Communications.
This is how the artist imagined the invisible hand of the acoustic hologram of the levitator
“With the help of our device, we can manipulate objects in the air and, as it may seem to some, violate the law of gravity. This is due to the fact that we individually control the work of dozens of micro-speakers, which allows us to create a kind of acoustic hologram that can move many objects in the air in real time, without touching them, said Sriram Subramanian of the university Sussex (UK).
Special attractive beams, capable of capturing and manipulating multi-ton fragments of matter, appear in many science fiction films and novels, in particular, in the science fiction series Star Trek. Scientists have repeatedly tried to create such devices, but they did not advance beyond theoretical developments and prototypes, which are extremely limited in functionality.
In 2013, Czech scientists took the first step towards creating such a device, learning how to lift microparticles of matter into the air and manipulate them using several laser beams of light.
Subramanian and his colleagues have been able to do much better and learn how to lift and move pea-sized droplets of liquid in the air using a system they call "acoustic holograms."
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They are a special combination of high-frequency and low-frequency sound waves, which, figuratively speaking, create a kind of "cage" around the held object and allow them to move in an arbitrary direction, changing the shape of this trap.
Using an experimental setup consisting of 64 microdynamics, the authors of the article were able to implement three key types of "acoustic holograms" - the so-called "forceps" that hold the captured matter in place and rotate it, "funnels" that move objects, and "bottles" that hold them in one position.
According to scientists, such an acoustic levitation system has no fundamental limitations. Their current invention is capable of holding and moving large droplets of liquids or other objects, but nothing prevents them from creating more powerful sound generators, or vice versa, miniaturizing them and using them to deliver drugs to the body or to perform very delicate operations - for example, removing kidney stones or inserting electrodes into the brain.
