Earthquakes: from Fukushima to Haiti, they leave behind nothing but death and devastation. A tool for predicting earthquakes could save lives, but infrastructure would still be at the mercy of plate tectonics. To make us even more helpless, the forces driving tectonic plates are enormous—it seems unlikely that prevention is ever going to be realistic. So we can’t predict them, and we can’t stop them. But what if we could hide from earthquakes?
On the face of it, the idea sounds ridiculous. The shaking of an earthquake is due to the propagation of pressure waves along the surface of the Earth. Surely, the only way to hide from an earthquake would be to leave the Earth, right? Not exactly. In optics, we know how to hide an object from light. These invisibility cloaks have been demonstrated, and they even sort of work. And a wave is a wave, so maybe, a group of researchers thought, this might be a fruitful approach for engineering.
The key here is a concept called a metamaterial. To understand metamaterials, let’s jump back into the world of optics. The way that light travels through a material is determined by nature—light may bend, slow down, or speed up as it enters different materials, depending on their properties. Materials do not have infinite variation, so it’s not possible to use material properties to get light to flow around an object to make it disappear from view, for instance.