A novelist’s vision of the virtual world has inspired an industry

IN THE LATE 1980s, a young author named Neal Stephenson was working on a project to create a graphic novel. He typed in some code on his Apple Macintosh II and a pair of spherical mirrors appeared on the screen, hanging in space. To make the images look more realistic, the code he used calculated how light bounced off the objects in the frame, so each mirror featured on it a convincing reflection of the other.