Glass partitions us from other people and the elements, while letting light through. But that transmission can be a problem if we want to have privacy or to block the sun's heat. Smart glass can help, letting us change the properties of windows on demand.

At the push of a button, liquid-crystal glass can rapidly transform from clear to frosted, turning a see-through conference room wall, shower stall or ambulance rear window into a visual barrier. No space-consuming or dirt-collecting shades, curtains or blinds are needed. This "privacy glass" is impossible to see through because it scatters incoming rays, yet the diffusion fills the interior space with natural light