The individual photos were at no time stopped.

I remember on the History channel "The Universe" light speed episode that light was stopped in some sort of sodium gas (I think sodium gas). Would that be considered "changing the effective refractive index"? They pretty much controlled the speed of the light and we watched it happen. They were real proud of themselves.

I remember on the History channel "The Universe" light speed episode that light was stopped in some sort of sodium gas (I think sodium gas). Would that be considered "changing the effective refractive index"? They pretty much controlled the speed of the light and we watched it happen. They were real proud of themselves.

 

Yes, although you can happily drop the effective in that case. I work mostly with metamaterials where the bulk refractive index is not that of the device we're dealing with.