Received from Yigit Turgut at 09/23/11 15:47 UTC:

>Refraction index depends on lots of parameters not just the wavelength of=
=20
>the source. It is a macroscopic manifestation of the molecular structure.=
=20
>It's a scale to compare materials ratios of interactions with vacuum where=
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>there is no interaction and light is at it's maximum speed. Since they=20
>artificially generate neutrinos they have the very specs of them. Also sin=
ce=20
>they constructed the tunnel specifically for this purpose, it is easy to=20
>calculate and measure the refractive index through the propagation medium=
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>(the tunnel), fairly easy process.


Not quite so easy because there isn't a 732 km tunnel.  Other than a bit of=
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tunnel housing the equipment on each end, the path is thru the earth.  I'm=
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sure the characteristics of that path can be estimated fairly closely, but=
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how do they know for sure?  What are the margins of error on that=20
estimate?  Would we still have faster than light neutrinos if we assume one=
=20
or the other bookend values for the speed of light along that path.

Light is fastest in a vacuum.  It's slower in all other media.  If the spee=
d=20
of light calculated for the rocky path is too low, then neutrinos travellin=
g=20
at the true speed of light in that medium will appear to be travelling fast=
er=20
than light should travel in that medium.



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