We live in a world of glowing rectangles. Our devices emit a bluish light, akin to that from the cerulean sky. Even when they sleep, computers softly pulse tiny LEDs on and off, making their presence known through light. And where they were once uniformly black and dark gray, devices are now white, shiny, and reflective: they add light not just by emitting it, but by reflecting it. The airbrushed aluminium of Macintosh computers has a luminous flux that ranks higher on light meters than pure, snowy white.