By injecting specialized light-tweaking nanoparticles into a mouse’s retina, that mouse is suddenly and clearly able to perceive near-infrared light — suggesting the same could be possible for us, assuming you don’t mind a needle in the eye. The advance involves what the researchers, from the University of Science and Technology in China, call “ocular injectable photoreceptor-binding upconversion nanoparticles.” In fact, it turns out that these researchers had already created the necessary trickery for a different reason, namely as a molecule for optogenetic triggers that would absorb infrared light (which conveniently penetrates many tissues) and emit visible spectrum light instead....