American physicists have created an “invisible lid” for submarines.
American physicists and engineers have developed a metamaterial that makes any underwater object "transparent" to sound waves and invisible to sonars. They presented their development at the annual meeting of the Acoustical Society of America in Washington.
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As Amanda Hanford of the University of Pennsylvania in Philadelphia notes, scientists have created dozens of structures that perfectly reflect or transmit sound waves, but all of them only work in the atmosphere. Making a “stealth cap” that works in water would be more difficult, because water is much denser.
Engineers from the United States have solved this problem - their metamaterial does not let sound waves pass through, but reflects sound in such a way that the observer seems to be looking at the flat bottom of a sea, river or ocean.
In structure, it resembles a one-meter-high pyramid, covered with numerous steel plates with many holes that can absorb and transform sound vibrations. According to scientists, its size and structure can be easily changed in the future, which will protect underwater objects from high-frequency vibrations and hide submarines and bathyscaphes (autonomous devices that study the depths of the sea) from echosounders.
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