How Metamaterials Work:
Metamaterials are stuff that we humans have made — you won’t find them in nature. And these materials are made in such a way that they can have properties that are either really uncommon or don’t occur at all in the natural universe as we know it.
See, conventional materials have properties that are determined by the individual atoms and molecules they are made of. In other words, a gold brick’s properties are due to all those wacky gold atoms. The chemical composition of the material gives it its properties.
But metamaterials get their properties not from the kind of atoms inside them but from their physical structure. It’s not the chemical composition that matters — it’s how the atoms are physically stacked together and patterned within the metamaterial.
They’re built to interact with electromagnetic radiation and physical force in weird and wonderful ways, and may eventually make sci-fi stuff like cloaking devices (and impossible-sounding things like a substance that expands when you squish it and contracts when you stretch it) possible.