The speed at which light travels through a vacuum, about 186,000 miles per second, is enshrined in physics lore as a universal speed limit.
Nothing can travel faster than that speed.
Einstein's theory of relativity would crumble, theoretical physics would fall into disarray, if anything could. Two new experiments have demonstrated how wrong that comfortable wisdom is. In the most striking of the new experiments a pulse of light that enters a transparent chamber filled with specially prepared cesium gas is pushed to speeds of 300 times the normal speed of light. That is so fast that, under these peculiar circumstances, the main part of the pulse exits the far side of the chamber even before it enters at the near side. By manipulating the way light passes through tissue, a team at the University of Texas at Austin has moved into what was once the realm of science fiction.