Just as loud noises can make small objects jitter on a table, powerful acoustic vibrations can lift things like toothpicks or water droplets into mid-air. Rather than just letting them levitate, though, researchers from the University of Tokyo and Nagoya Institute of Technology set tiny particles in a dance between shifting, overlapping ultrasonic beams that could shift them around a small cubic space. The resulting video combines graceful, gravity-defying motion with an explanation of how the system actually works, and the full research paper goes deeper into the technology's precise details.
The roughly millimeter-sized balls that perform the most impressive stunts are composed of polystyrene, but the group also tested screws, matchsticks, and other objects — other researchers have successfully levitated ants and even small fish. While the sound must be extremely intense, its high frequency makes it inaudible to human ears, and levitation can open up new ways for us to manipulate objects. Earlier this year, another group of researchers made a similar breakthrough in moving floating particles, mixing together solutions in mid-air without fear of contamination from a container.