Researcher Amanda D. Hanford at Pennsylvania State University has created a real cloaking device that can route sound waves around an object, making it invisible to some sensing techniques.
From the report:
Hanford and her team set out to engineer a metamaterial that can allow the sound waves to bend around the object as if it were not there. Metamaterials commonly exhibit extraordinary properties not found in nature, like negative density. To work, the unit cell — the smallest component of the metamaterial — must be smaller than the acoustic wavelength in the study.
Hanford created an acoustic metamaterial that deflected sound waves under water, a difficult feat. In testing she and the team were able to place the material in water and measure sound waves pointed at it. The resulting echoes in the water suggested that the sound waves did not bounce off or around the material. This means the new material would be invisible to sonar.
Obviously this technology is still in its early stages and the material does not make the objects invisible but just very hard to detect in underwater situations. However, the fact ship captains could soon yell “Activate the cloaking device” as evil, laser-toting dolphins appear on the horizon should give everyone a bit of cheer.
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