Scientists Create Real-Life Cloaking Device

Star Trek fans, today may be a day to rejoice as one of your favorite techs just got one step closer to becoming a reality.  The research hits home as it stems from our own passion, relating to audio. Researcher Amanda D. Hanford at Pennsylvania State University has taken the introductory steps to making acoustic ground cloaks. The materials used in this experiment redirect approaching waves around an object without scattering the wave energy, concealing the object from the sound waves thus 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.

A team lead by Dr. Hanford constructed a 3-foot-tall pyramid out of perforated steel plates as seen in the image in this article.  The structure was placed on the floor of a large underwater research tank where a source hydrophone produced acoustic waves between 7,000 Hz and 12,000 Hz. Several receiver hydrophones were placed around the tank to monitor reflected acoustic waves. This metamaterial (sounds like something borrowed from the Flash universe) was able to deflect sound waves under water. The resultant echoes in the water suggested that the sound waves did not bounce off or around the material. Basically the waves reflected from the metamaterial matched the phase of the reflected wave from the surface while the amplitude of the reflected waves from the material actually decreased slightly. This means the new material would be invisible to sonar.  Could this be grounds for a sequel to The Hunt for Red October? If so, tell Sean Connery to send them one ping only please.

This technology is still in its infancy and the material doesn't actually make objects invisible, just really hard to detect in underwater situations. Imagine the day when captains of submarines can say "Red Alert: activate the cloaking device"!  Now if only they can take this technology one step further to make hulking subwoofers invisible to our wives, they may just be on to something.