Electrical Pulses Break Light Speed Record

J'raxis writes "PhysicsWeb writes that 'Pulses that travel faster than light have been sent over a significant distance for the first time. Alain Haché and Louis Poirier of the University of Moncton in Canada transmitted the pulses through a 120-metre cable made from a coaxial 'photonic crystal.' Haché and Poirier emphasize that their experiment does not break any laws of physics. Although the group velocity exceeds the speed of light - an effect permitted by relativity -- each component of the pulse travels slower than light.'"

Comments

It's the shape of the pulse...

[Crispy Critters]

What is happening here is that they are sending a pulse of light, and the envelope or shape of the pulse changes as it travels. Previous papers have shown a pulse that starts out as a Gaussian and becomes progressively more skewed as it propagates.

This allows the peak of the pulse to move faster than light speed. However, the leading edge of the pulse does not.

This is why this is not a technique for sending information faster than the speed of light.