CAMBRIDGE, Mass. Physicists at Harvard University have succeeded in slowing light to a mere one mile per hour. Light traveling in a vacuum is the fastest-moving object in the universe, according to the theory of relativity, but it will slow down when it enters some other medium.
The Harvard researchers achieved their results by passing light through a special state of matter known as a Bose-Einstein condensate, which can exist only at close to absolute zero. If the effect could be recreated in a technologically practical device, it could lead to very low-powered nonlinear optics, said Lene Verstergaard Hau, one of the Harvard researchers who reported the result at a meeting of the American Association for the Advancement of Science held recently in Washington.