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Old 10-15-2011, 11:33 AM   #16
Lamplighter
Person who doesn't update the user title
 
Join Date: Jun 2010
Location: Bottom lands of the Missoula floods
Posts: 6,402
Hey, I may have been closer to the answer than I thought !
Quote:
Originally Posted by Lamplighter View Post
He's much too polite to say it, but everyone knows that when Mussolini made the trains run on time, he did it by making the clocks run slower.
Today, the news is reporting there may be a solution to the original problem...
MIT Technology Review (blog)
kfc 10/14/2011
Faster-than-Light Neutrino Puzzle Claimed Solved by Special Relativity
Quote:
The relativistic motion of clocks on board GPS satellites
exactly accounts for the superluminal effect, says physicist.
This article has an explanation for laymen of the proposed solution:
Quote:
It's easy to think that the motion of the satellites is irrelevant.
After all, the radio waves carrying the time signal must travel
at the speed of light, regardless of the satellites' speed.
But there is an additional subtlety.

Although the speed of light is does not depend on the the frame of reference, the time of flight does.
In this case, there are two frames of reference: the experiment on the ground and the clocks in orbit.
If these are moving relative to each other, then this needs to be factored in.

So what is the satellites' motion with respect to the OPERA experiment?
These probes orbit from West to East in a plane inclined at 55 degrees to the equator.
Significantly, that's roughly in line with the neutrino flight path.
Their relative motion is then easy to calculate.

So from the point of view of a clock on board a GPS satellite,
the positions of the neutrino source and detector are changing.

"From the perspective of the clock, the detector is moving towards the source
and consequently the distance traveled by the particles
as observed from the clock is shorter," says van Elburg.
By this he means shorter than the distance measured in the reference frame on the ground.

The OPERA team overlooks this because it thinks of the clocks as on the ground not in orbit.
How big is this effect? Van Elburg calculates that it should cause the neutrinos to arrive 32 nanoseconds early.
But this must be doubled because the same error occurs at each end of the experiment.
So the total correction is 64 nanoseconds, almost exactly what the OPERA team observes.

If it stands up, this episode will be laden with irony.
Far from breaking Einstein's theory of relatively,
the faster-than-light measurement will turn out to be
another confirmation of it.

Ref: arxiv.org/abs/1110.2685: Times Of Flight Between A Source And
A Detector Observed From A GPS Satellite.
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