[annie123 (OP)]

Since Lene Vesergaard Hau has managed to slow down the speed of light and actually stop it ,by passing it through a different medium, is it theoretically possible for someone to pass light through something other than space  - which, if it full of dark matter is hardly a vacuum - or other mediums (media?) and speed it up?

[CliffordK]

The better the vacuum, the faster the speed of light, but at some point, one would be unable to make a significant difference.

I bumped into an interesting observation by the  MAGIC Telescope suggesting that the higher energy photons may in fact travel slower than the lower energy photons.  This just seems counter-intuitive, as I would expect the higher energy photons to be the same speed, or faster. 

Anyway, if these findings hold up, then it is possible that longer wave length radio waves would be found to travel faster than shorter wavelength x-rays, although the differences may only be detectable when observing the ultra-high-energy gamma ray photons.

[ScientificSorcerer]

How the hell do you do that anyway?? I would love to repeat those light stopping experiments but I can't seem to find out how to set up the experiment I know it has do do with lasers crystals and BEC. Imagine If you could use that technology as some sort of optical capacitor, collecting and storing light then wam! let it all out at ones could be useful for storm troopers.