[QuestionWriter]

If synchronized clocks are a problem, I wonder why they don't race the neutrino against a photon. Obviously the photon would have to take a different path - maybe bouncing off a satellite.

I wonder how accurate the GPS synchronization is too. I'm wondering if it takes into account different atmospheric conditions and the index of refraction of radio waves in air.

[lutorm]

Time measurements are interestingly difficult when you start to care about high accuracy or long times. There's a kind of hard-to-read but interesting running log on the state of the leap second at http://www.ucolick.org/~sla/leapsecs/onlinebib.html. (What, you didn't know there were leap seconds? See http://en.wikipedia.org/wiki/Leap_second)

[pbhjpbhj]

How about two pairs atomic clocks. One paired at the start point, one paired at the end point then a start- and an end-clock being used in both locations? Or use a neutral third frame of reference by timing from a pulsar.

This probably wouldn't work, time dilation under gravity makes my head hurt!

[VladRussian]

>If synchronized clocks are a problem, I wonder why they don't race the neutrino against a photon. Obviously the photon would have to take a different path - maybe bouncing off a satellite.

how about just inside the fiber. How good is the ping between CERN and Gran Sasso ? :)