Excerpted from: http://dvice.com/archives/2011/10/speedy-neutrino.php
Here's the deal: neutrinos move very very fast (at or close to light speed, at least), and the distance that they traveled in this experiment was (to a neutrino) not that far, only 450 miles. This means that in order to figure out exactly how long it takes a given neutrino to make the trip, you need to know two things very, very precisely: the distance between the two points, and the time the neutrino leaves the first point (the source) and arrives at the second point (the detector).
In the original experiment, the CERN researchers used GPS to make both the distance measurement and the time measurement. They figured out the distance down to about 20 centimeters, which is certainly possible with GPS, and since GPS satellites all broadcast an extremely accurate time signal by radio, they were also used as a way to sync the clocks that measured the neutrino's travel time. The CERN team had to account for a lot of different variables to do this, like the time that it takes for the clock signal to make it from the satellite in orbit to the ground, but they may have forgotten one critical thing: relativity.
It's All Relative
Relativity is really, really weird. It says that things like distance and time can change depending on how you look at them, especially if you're moving very fast relative to something else. In the case of the neutrino experiment, we've got two things to think about: the detectors on the ground that measure where and when the neutrinos depart and arrive, and the GPS satellites up in space that we're using as a basis for these measurements. Since the satellites are orbiting the Earth and moving way faster than the detectors, we say that they're in a different "reference frame," which just means that the motion of the satellites is significantly different than the motion of the Earth.
Part of the deal with relativity is that neither of these reference frames are the "correct" one. From our perspective here on Earth, the satellites are whizzing around in orbit at about 9,000 miles per hour. But the perspective of the satellites, the Earth is whizzing around just as fast, and the difference in velocities between these two reference frames is large enough that some strange things start to happen.
(So RT is preserved - by RT itself - Mal)