"Sam Wormley" escreveu na mensagem
news:tXtTj.96038$TT4.72561@attbi_s22...
El Enrrabadore-mor wrote:
It is said that a speeding clock shows less elapsed time than
the stay-at-home clock, because (if already speeding) it is
running at a slower rate. Or else, because it had run at a
slower rate when it was speeding, assuming now it is
stopped near the stay-at-home clock.
What I meant to say is... for satellite clocks in orbits
approximating circular motion, time dilation is dependent
on altitude in the gravity well as well as relative velocity.
See graph in second link.
Relativistic Effects on Satellite Clocks
http://relativity.livingreviews.org/...age=node5.html
http://relativity.livingreviews.org/...-1/frctfrq.png
Take some time to learn what really happens.
What really happens looks to be the following:
- 98% is Sagnac effect (a non relativistic effect that is said
to contradict SR on its most basic postulate about light)
- 2% is due to all other effects (relativity, excentricities, and so on).
References:
- A QUOTE (from your link):
"GPS can be used to compare times on two earth-fixed clocks when a single
satellite is in view from both locations. This is the "common-view" method
of comparison of Primary standards, whose locations on earth's surface are
usually known very accurately in advance from ground-based surveys. Signals
from a single GPS satellite in common view of receivers at the two locations
provide enough information to determine the time difference between the two
local clocks. The Sagnac effect is very important in making such
comparisons, as it can amount to hundreds of nanoseconds, depending on the
geometry. In 1984 GPS satellites 3, 4, 6, and 8 were used in simultaneous
common view between three pairs of earth timing centers, to accomplish
closure in performing an around-the-world Sagnac experiment. The centers
were the National Bureau of Standards (NBS) in Boulder, CO,
Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, West Germany,
and Tokyo Astronomical Observatory (TAO). The size of the Sagnac correction
varied from 240 to 350 ns. Enough data were collected to perform 90
independent circumnavigations. The actual mean value of the residual
obtained after adding the three pairs of time differences was 5 ns, which
was less than 2 percent of the magnitude of the calculated total Sagnac
effect [4]."