[Physicist]

Yeah, I understand that, but what kind of an analogy can you come up with that the average guy would understand?

I've illustrated the "photonic bandgap" problem as a long train leaving Washington D.C. for Baltimore, where the length of the train is a significant fraction of the distance between the cities. The train is not said to "leave" or "arrive" until the center of the train gets to the station. Just as the train is approaching Baltimore, the engine detaches from the rest of the train, and it "arrives" in Baltimore when the center of the engine gets to the station, which happens to be in record time.

[Brilliant]

Nice try. I'm not sure that would clear it up to the average guy, though.


Another way I've heard it explained is in reference to water waves... Drop a stone in the water and watch the waves. It's not just one wave, but several ripples which spread out in concentric circles from the point of impact. The wave front moves at a specific rate of speed, which is the group velocity analogous to the speed of light, but if you look at each ripple in the group, and follow it carefully, then you will notice that each ripple starts at the inside of the circle of waves, then slowly moves up the pack until it is on the outside of the wave packet. Obviously, the ripples are each moving faster than the wave packet as a whole. That is the phase velocity.

But it's still a little esoteric for the Bud Light crowd.

[Southack]

"Continuing, he explained that the pulse flowing backward also releases a forward pulse out the end of the medium, a situation that causes the pulse entering the front of the material appear to move out the back almost instantly. "In this way, one can argue that that the wave packet travels with velocities much higher than the velocities of light," said Soukoulis."

Is he saying that he can transmit wave packets (read: potential data) faster than C for the length of his negatively-refracting medium?

[Seamoth]

In other words, there exist mediums such that the speed of light remains constant, but will stretch out the wavelength like a curved mirror, such that the ends will go faster than c during the stretching, but the overall speed remains c?