Phys.org  December 7, 2021 According to the researchers in Hong Kong the absence of shear force in the air, or fluids, makes sound waves longitudinal. Synthetic shear force may arise if the air is discretized into “meta-atoms,” whose collective motion can give rise to a transverse sound on the macroscopic scale. To implement this idea they designed micropolar metamaterial like a complex network of resonators. Air was confined inside the mutually connected resonators, forming the meta-atoms. Through theoretical calculations they showed that the collective motion of meta-atoms produces the shear force, which gives rise to the transverse sound with spin-orbit […]