NEC researchers break light speed barrier

In a breakthrough that could pave the way for faster communications systems, researchers at NEC's Research Institute in Princeton, New Jersey, have succeeded in making pulses of light travel 310 times faster than normal.

To come up with their astonishing result, the team measured the time it takes for a pulse of light to travel through a 60 millimeter-long chamber of cesium gas. The pulse traveled through the cesium 310 times faster than it would have traveled through a vacuum, the researchers said. This made it appear, in our frame of reference, to have left the chamber even before it entered.

Full details of the work by NEC research scientists Dr. Lijun Wang, Dr. Alexander Kuzmich and Dr. Arthur Dogariu appear in the July 20 edition of the scientific journal Nature.

The unusual phenomenon is the result of something called anomalous dispersion. The effect is created by the cesium gas, which causes the many waves of light that make up the pulse to be modified. Inside the cesium-filled chamber short wavelength light becomes long wavelength and vice versa, enabling the light waves to "re-phase" and appear as a pulse of light at a distant point.

"Our experiment is not at odds with Einstein's (theory of) special relativity," said the researchers in their statement. "The experiment can be well explained using existing physics theories that are consistent with relativity. In fact, the experiment was designed based on calculations using existing physics theories. However our experiment does show the generally held misconception 'nothing can move faster than the speed of light' is wrong." This assumption, they said, only applies to things with mass but as light has no mass, it is not limited by its speed in a vacuum.

How the experiment might be applied in the real world is still under study but the researchers did offer some hints at what the likely benefits might be. "Using this effect, one might be able to increase information transfer at speeds up to 'c' (the speed of light in a vacuum). In present day technology, information is transmitted at speeds far slower than 'c' in most cases such as through the Internet and inside a computer."

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