Metamaterials offer a path through the looking glass: "Inside the metamaterial, the light travels diagonally backwards before hitting an angled mirror directly behind the metamaterial chunk. It is reflected back through the metamaterial and is negatively refracted once more as it leaves the wall and returns to the corridor. Consequently, on re-entering the corridor, the light travels back towards the light source.
A viewer looking down the corridor would be unaware of the unusual path taken by the light entering it. They would simply see themselves apparently reflected in a mirror blocking the corridor at an angle – although in reality the mirror reflecting them is embedded behind the metamaterial that forms one wall of the corridor."