A simple plastic shell has cloaked a three-dimensional object from sound waves for the first time. With some improvements, a similar cloak could eventually be used to reduce noise pollution and to allow ships and submarines to evade enemy detection. The experiments appear March 20 in Physical Review Letters.
“This paper implements a simplified version of invisibility using well-designed but relatively simple materials,” says Steven Cummer, an electrical engineer at Duke University, who was not involved in the study. Cummer proposed the concept of a sound cloak in 2007.
Scientists’ recent efforts to render objects invisible to the eye are based on the fact that our perception of the world depends on the scattering of waves. We can see objects because waves of light strike them and scatter. Similarly, the Navy can detect faraway submarines because they scatter sound waves (sonar) that hit them.
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