The Gaven

First proposed in 2008, scientist have now developed an acoustic cloaking device that makes objects invisible to sound.

It uses simple plastic sheets with arrays of holes, and could be put to use in making ships invisible to sonar or in acoustic design of concert halls.

Those approaches are mostly based on so-called metamaterials, man-made materials with properties that do not occur in nature. The metamaterials are designed such that they force light waves to travel around an object; to an observer, it is as if the object were not there.

But researchers quickly found out that the mathematics behind bending these light waves, called transformation optics, could also be applied to sound waves.

All the proposed theories in The Gaven are quickly becoming probable instead of something in the near future.