Slow Photons

[qube_TA]

Looking at this article - http://www.bbc.co.uk/news/uk-scotland-glasgow-west...

If the speed of light can be slowed down, would that mean that the Universe could actually be much smaller (or bigger) than it appears if the light we see was running slow?

[Toaster]

Light would have to pass through the "special" filter to reduce the speed in the same way and a key questions are: is there a naturally occurring filter and how many of these are there?

another thought is if it went through a another type of filter would it speed up again

[Simpo Two]

Perhaps - but you'd have to add energy from somewhere.

[Twobad]

It's the group speed of the photons which is slowed not the individual ones (even if there's only one photon in the experiment st a time it can still exhibit group behaviour, because they're awkward like that). So special relativity and C, the speed of light remain intact. Which is nice.

http://physicsworld.com/cws/article/news/2015/jan/...