Faster-than-light electric pulses
Canadian scientists have sent electric pulses over long ranges at speeds faster than light for the first time.
The researchers believe their findings may one day help greatly increase computer and telecommunications speeds.
"The most important part of the finding is that it is the first time something -- anything -- was seen traveling over such distances at superluminal speeds," said lead researcher Alain Hache, a physicist at the University of Moncton in Canada.
The investigators stress it is not theoretically possible to send useful data at superluminal or faster than light velocities. However, they believe their results may help speed up electronics by more than half.
"Right now, the signal velocity in any wire -- a wire inside a computer chip, a phone wire -- is only a fraction of the speed of light," Hache said in an interview with United Press International. "One might one day accelerate those pulses up to the speed of light."
The speed of light is theoretically the fastest possible. First measured in 1675 by analyzing sunlight reflected off the moons of Jupiter, light speed is roughly 670 million miles per hour in vacuum -- fast enough to go around the Earth in about a tenth of a second.
The theory of relativity proposed by Einstein suggests exceeding the light barrier would lead to impossible results, such as cause after effect -- time travel. Scientists, however, have experimentally broken this speed limit for the past two decades, transmitting light pulses that move at superluminal speeds.
The key to understanding this apparently impossible phenomenon is to visualize a pulse of light as a group of waves all intermingled with each other. This group pulse rises and falls in energy over space, with a peak of strength in the middle.
Materials that absorb or disperse light can force the different waves in a group pulse to shift. The waves making up the rear of this pulse can be made to interfere with each other to drive the pulse's peak forward in space, resulting in the pulse traveling at superluminal speed.
Scientists were previously able to generate superluminal pulses of light over very short distances of only a few feet at most using very complex equipment. The research team managed to generate electric pulses that moved faster than light over a simple wire for the first time -- signals that moved at three times the speed of light over more than 500 feet.
The researchers connected a series of off-the-shelf store-bought wires together, each with different electrical resistance levels. This created reflections in the signals for the superluminal effect.
"The same laws that apply for light waves also apply for electrical waves," Hache explained.
Do not expect superluminal starships or time machines anytime soon, however. Since the energy that makes up the group pulse does not actually travel faster than light, the theory of relativity remains unbroken. A signal also gets weaker and more distorted the faster it goes, so it is theoretically impossible to send useful information at superluminal speeds.
However, the researchers do hope to use their reflection technique to help increase the speed of electrical signals traveling down existing telecommunication cables.
"At the moment, plain coaxial cables allow a velocity of about two-thirds the speed of light," Hache said. "By texturing the cable... we might bring that limit closer to light speed. There would be a lot of applications for that, like in computers when you send a bit from A to B."
Superluminal physics expert Mohammad Mojahedi, an electrical engineer at the University of Toronto, said this work may help move faster-than-light phenomena "from the physics aspect to the engineering aspects, to make faster devices."
(Reported by Charles Choi in New York.)
