In ordinary water, a stone's ripple spreads in even circles. But if the fluid consists of molecules resembling right-handed screws, the surface acts like a one-way street. In such a chiral fluid, odd viscosity arises, giving birth to two types of waves: one is the familiar ripple, the other is almost like sound, traveling without changing speed. These waves interact so that the standing ripple begins to crawl, and a vortex spins beneath the surface. When odd viscosity exceeds a threshold, particles on the surface drift opposite the wave direction — reverse drift. This irreversible process increases the system's entropy. The effect could form the basis for micro-pumps with no moving parts. The broken mirror symmetry here is akin to the Standard Model of particle physics with its weak interaction, but unlike gravitational waves, these waves live at the interface of two media.
Water striders glide on water using capillary waves. If their pond became chiral, these insects would have to relearn how to walk — or they'd drift helplessly backward.