A team of researchers at Pennsylvania State University, led by Amanda D. Hanford, has developed a “cloaking device” that works underwater. The new metamaterial shield is able to intercept and bend underwater sound waves, like sonar, around it without scattering them – making it appear as if the cloak and anything within it isn’t there at all.
Metamaterials are materials designed to exhibit properties not found in nature. They are generally constructed from composite materials, like metals, plastics, or ceramics, and engineered into repeating, microscopic structures.
In the case of the underwater acoustic cloak, the goal was to make a metamaterial that could do for submarines or undersea installations what science fiction cloaking devices do for Klingon warbirds. Acoustic cloaking has already been achieved in the lab, but only in the air. Water is much more of a challenge because it’s denser and much less compressible than air, which limits cloak engineering options.