Researchers at the Max Planck Institute in Germany are moving paper boats, levitating bubbles and making dove-shaped water rings using sound. "If you want to generate a complicated sound field, you need a large number of sound sources," Fischer said. The underwater acoustic hologram projects sound waves toward the surface of the water to generate complex sound fields, such as the two rings that can be seen on the water surface. By arranging silicone spheres on the surface of water, scientists can make that acoustic "picture" visible. They can also alter the sound field to manipulate objects — say, levitate a droplet of water, or cause a tiny boat to zoom around.

Source: Washington Post September 21, 2016 17:09 UTC