LIGHT, it turns out, can be coaxed into racing off at top speed, even in a substance where it usually moves slowly. The result hints at a possible way to speed up computers and communication networks.
Scientists generally assumed that in any given medium, a light signal cannot travel faster than the “group velocity” – the speed of a broad pulse of light. In glass, for example, the group velocity is about 0.67 times c, the speed of light in a vacuum. But experiments by Daniel Gauthier from Duke University in Durham, North Carolina, and his colleagues at the University…
