Invisibility cloak designs make it impossible for anyone hiding under the cloak to see what’s going on in the outside world. Now Nanjing University researchers have come up with a solution: make a tiny tear in the cloak, then stitch the hole with two types of materials chosen to effectively cancel each other out when seen from the outside, while still allowing light to enter — the equivalent of the one-way mirrors used in police interrogation rooms.

Ref.: Jin-Zhu Zhao, et al., Peering Out from Under an Invisibility Cloak, Physical Review E, 2011; (in press)