Metamaterials researchers have created a thin plastic structure with geometric details allowing it to control the redirection and reflection of sound waves with almost perfect efficiency.

The earliest scientists first observed the waves that earthquakes produce before they could accurately describe the nature of earthquakes or their fundamental causes, as discussed in Lessons 1–5.

The interface between two facets of an artificial material known as a “Weyl phononic crystal” can not only negatively refract an airborne sound wave, it does so without reflecting it at all. This ...