On 10/16/2011 02:39 AM, Javier Herrero wrote:
El 16/10/2011 02:14, [email protected] escribió:
And further, what the author states, in other words, would mean that
the two clocks at Earth, in the frame in which the measurement was
made, were off by 60 ns, isn't it?
More or less :) I'm also not sure of the accuracy of the phrase "The
clocks in the OPERA experiment are orbiting the earth in GPS
satellites", since as far as I've understood the GPS is used to use
common view for comparison of the Cs clocks. And it seems that the
author does not know that relativity has already been taken into account
in the GPS system.
A first compensation of relativity is done by shifting the frequency
such that the fixed satellite would use 10,23 MHz as observed from the
earth. This frequency is used in 120, 154, 1 and 1/10 multiples for
carries and chip-rate of pseudo-random noise in the set of gears
providing time distribution. The one relative effect which they maybe
didn't account for is the Sagnac effect, which Tom estimated being about
2.3 ns which matches the difference found in the time-difference
testing. This effect comes from the spinning of the earth.
Much of the effects is first degree compensated when doing a common view
comparision, and the GPS clock is only a transfer clock, not the clock
of the measurement.
A much more detailed analysis would be required of the timing system
then provided by that 4 page paper, detailing the processes in the GPS
receivers, post-processing etc. Also, a full review of the timing system
would need to analyse the internal distribution system and verify that
on both sites. Also, the timing of the neutrinos in the detectors and
their location when detected etc also needs to be looked at. So far, I
have only been looking at this quickly and the reasonability of things
being done correctly. Both the main paper and the PTB preliminary report
is unsatisfactory in the details for full analysis, but they seem
reasonable.
I'm of the same opinion as Magnus: I do not think that this paper will
bebunk the OPERA one, not even a little :)
Indeed. It was a very sloppy attempt.
Cheers,
Magnus
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