Materials science is advancing in leaps and bounds, creating what was previously impossible.
Metamaterials are simply materials that have been engineered to exhibit properties that are not found in nature. In this case, the structural design of the metamaterial gives it qualities that make it a “hyperbolic” metamaterial. This means that it interacts with acoustic waves in two different ways. From one direction, the metamaterial exhibits a positive density and interacts with acoustic waves normally – just like air. But from a perpendicular direction, the metamaterial exhibits a negative density in terms of how it interacts with sound. This effectively makes acoustic waves bend at angles that are the exact opposite of what basic physics would tell you to expect.
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