Magic material is both a reflecting mirror and a see through window

　　No, it's not a one way mirror. It's much cooler than that. MIT scientists have invented a new invisible mirror that can show reflections like a typical mirror but also be see through like a window. The magic is in the alternating 84 ultra thin layers typical glass and tantalum oxide. It's a mirror but when you spin it, it becomes transparent. Some light passes through, some light gets reflected.

　　New Scientist writes:As light passes from one of these layers to the next, some gets partially reflected – except for light that approaches from a certain angle. Any light that hits the surface of a layer at this so-called Brewster angle, and with a particular polarisation, will pass straight through as if the surface wasn't there. The Brewster angle is different for each pair of materials as it depends on their refractive indices.