Glow-in-the-dark devices, which emit visible light after exposure to sunlight, are as commonplace as a wristwatch. But these are not that great when you want to see and not be seen — say you’re a special ops soldier checking the time while tracking an enemy. In that situation, a glow-in-the-night-vision device would be far more effective. Now scientists at the University of Georgia have invented just such a device — a new material that emits a long-lasting infrared glow after a single minute of exposure to light. You can only see the light through night-vision glasses.
