On Fri, Sep 23, 2011 at 9:00 PM, Jim Higgins wrote: > Received from Yigit Turgut at 09/23/11 15:47 UTC: > >>Refraction index depends on lots of parameters not just the wavelength of >>the source. It is a macroscopic manifestation of the molecular structure. >>It's a scale to compare materials ratios of interactions with vacuum wher= e >>there is no interaction and light is at it's maximum speed. Since they >>artificially generate neutrinos they have the very specs of them. Also si= nce >>they constructed the tunnel specifically for this purpose, it is easy to >>calculate and measure the refractive index through the propagation medium >>(the tunnel), fairly easy process. > > > Not quite so easy because there isn't a 732 km tunnel. =A0Other than a bi= t of > tunnel housing the equipment on each end, the path is thru the earth. =A0= I'm > sure the characteristics of that path can be estimated fairly closely, bu= t > how do they know for sure? =A0What are the margins of error on that > estimate? =A0Would we still have faster than light neutrinos if we assume= one > or the other bookend values for the speed of light along that path. Whole propagation path is not vacuum surely, but the path geometry and total distance is estimated safely. Maybe not precise down to cm scale but I believe it's an acceptable approximation. Can't say numbers safely about the error margins but the measurement points to a speed approximately 400 times more than the speed of light. It would be still much more faster than "c" even if the propagation path measurement has precision at km scale. The actual tolerance mentioned on the original paper is originating from the heterogeneous and anisotropic structure of the path after the vacuum tunnel. Exact permittivity and conductivity tensors of the mediums between first muon detector and Gran Sasso should be known for very high accuracy calculations - which is not possible with today's tech. If between medium was isotropic and homogeneous, propagation path could be determined at nanoscale precision. Which I am sure that they would construct the whole path as the tunnel if it was a requirement for gathering the same results. Obviously, not necessary. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .