Speed of Light No Longer the Limit

ByABC News
July 19, 2000, 6:25 PM

July 19 -- Scientists have apparently broken the universes speed limit.

For generations, physicists believed there is nothing fasterthan light moving through a vacuum a speed of 186,000 miles persecond.

But in an experiment in Princeton, N.J., physicists sent a pulseof laser light through cesium vapor so quickly that it left thechamber before it had even finished entering.

The pulse traveled 310 times the distance it would have coveredif the chamber had contained a vacuum.

Researchers say it is the most convincing demonstration yet thatthe speed of light supposedly an ironclad rule of nature can bepushed beyond known boundaries, at least under certain laboratorycircumstances.

This effect cannot be used to send information back in time,said Lijun Wang, a researcher with the private NEC Institute.However, our experiment does show that the generally heldmisconception that nothing can travel faster than the speed oflight is wrong.

The results were published in Thursdays issue of the journalNature.

The achievement has no practical application right now, butexperiments like this have generated considerable excitement in thesmall international community of theoretical and opticalphysicists.

Previously Thought ImpossibleThis is a breakthrough in the sense that people have thoughtthat was impossible, said Raymond Chiao, a physicist at theUniversity of California at Berkeley who was not involved in thework. Chiao has performed similar experiments using electricfields.

In the latest experiment, researchers at NEC developed a devicethat fired a laser pulse into a glass chamber filled with a vaporof cesium atoms. The researchers say the device is sort of a lightamplifier that can push the pulse ahead.

Previously, experiments have been done in which light alsoappeared to achieve such so-called superluminal speeds, but thelight was distorted, raising doubts as to whether scientists hadreally accomplished such a feat.