S
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GPS World: USNO's Fountain: Time at 100 Trillionths of a Second
S
Sue...
They certainly are, but the details of the oscillator and acceleration
affect the amount.
This depends in detail on the timekeeping mechanism, and the type of
acceleration.
Commercial cesium atomic clocks have specifications for this, and
manufacturers have most definitely tested this. I believe many such
clocks can stand about 2 g and remain within their timekeeping
specifications. Certainly they have been operated successfully in
automobiles and airplanes.
Modern fountain clocks depend on the acceleration of gravity for their
operation and will fail for any other acceleration (internally they put
cesium atoms in a freefall "fountain" and measure their hyperfine
transition; other accelerations wouldn't affect the atoms, but their
trajectory would be incorrect and the mechanism couldn't measure them).
I believe the atomic clocks in GPS satellites are not running during
lift-off. They are not fountain clocks, of course, but they operate
within spec both on earth (1 g) and in orbit (~10^-6 g).
In Gravity Probe A a hydrogen maser was operating during lift-off and
re-entry of a Scout rocket; comparison to ground-based clocks throughout
the flight agreed with the prediction of GR, in which acceleration does
not affect the timekeeping.
<< Muon decay, for example, largely seems to
ignore possible cross-section dependence on the
velocity of the projectile and secondary production.
The clocks-around-the-world experiment has
been strongly criticized for its data reduction
techniques. In particular, the existence of time
delay effects for transported clocks has been
questioned.[23] Without access to the details
of these experiments and their subsequent data
analysis, one is not in position to do deep critical
analysis; nevertheless, there is sufficient
information in the literature to reasonably justify considering
conclusions drawn on their basis
as disputable. Moreover, experience with contemporary communication
technology seems to present
numerous practical reasons to question the
conventional understanding of time delay effects for transported
clocks.[24] >>
http://xxx.tau.ac.il/abs/quant-ph/0206164v1
Sue...
Tom Potter responded:
> [... utter nonsense indicating complete ignorance of the subject]
Tom Roberts
A
Androcles
the frequencies output from the atomic oscillators
in all of the satellites are adjusted to compensate
for the Galileo Effect.
As you may know,
Galileo discovered over 400 years ago
that oscillators were affected by acceleration,
and England sent ships all over the world with standard pendulums
to measure the acceleration at different places,
and Newton used this data to compute the mass of the Moon,
the shape of the Earth and tides all over the Earth.
Interesting idea. I can see how the frequency of mechanical
oscillators could be affected by variations in acceleration. I wonder
what would be the mechanism by which atomic clocks would be similarly
affected.
It would be interesting to do a test. I wonder if anyone has ever put
an atomic clock in a centrifuge. It would be easy to subject it to
several g of acceleration for a long period to see the effect on the
frequency of the clock.
--
Kevin Horton
=========================================
I'm sure Roberts will explain to you how such clocks
remain within specification, unaffected by acceleration,
and how they are affected by acceleration according to GR.
He may even mumble some drivel about error bars.
Error bars can be applied to Newtonian clocks but not to
relativistic clocks because Newtonian Mechanics is only
approximately correct and GR is purrfect.
T
Tom Potter
Tom Roberts said:Kevin said:I can see how the frequency of mechanical
oscillators could be affected by variations in acceleration.
They certainly are, but the details of the oscillator and acceleration
affect the amount.
I wonder
what would be the mechanism by which atomic clocks would be similarly
affected.
This depends in detail on the timekeeping mechanism, and the type of
acceleration.
It would be interesting to do a test. I wonder if anyone has ever put
an atomic clock in a centrifuge.
Commercial cesium atomic clocks have specifications for this, and
manufacturers have most definitely tested this. I believe many such
clocks can stand about 2 g and remain within their timekeeping
specifications. Certainly they have been operated successfully in
automobiles and airplanes.
Modern fountain clocks depend on the acceleration of gravity for their
operation and will fail for any other acceleration (internally they put
cesium atoms in a freefall "fountain" and measure their hyperfine
transition; other accelerations wouldn't affect the atoms, but their
trajectory would be incorrect and the mechanism couldn't measure them).
I believe the atomic clocks in GPS satellites are not running during
lift-off. They are not fountain clocks, of course, but they operate
within spec both on earth (1 g) and in orbit (~10^-6 g).
In Gravity Probe A a hydrogen maser was operating during lift-off and
re-entry of a Scout rocket; comparison to ground-based clocks throughout
the flight agreed with the prediction of GR, in which acceleration does
not affect the timekeeping.
The timekeeping mechanism that causes muons to decay is unaffected (at
the 0.1% level) by the truly enormous acceleration of 10^18 g (see the
FAQ and its reference to the experiment by Bailey et al).
Tom Potter responded:[... utter nonsense indicating complete ignorance of the subject]
Tom Roberts
The "utter nonsense" that bent Tom Roberts all out of shape.
========================================
I dare say that it would be easy to determine the "mechanism"
if a few billion taxpayers dollars were used to perform experiments,
and if 13 hacks using Classical Physics magnetic, electric,
windage, friction, temperature, velocity, etc. were used to
adjust the data to fit the results.
Of course, it would take all of the 13 Classical Physics hacks,
to adjust for all of the artifact that would result from using
a centrifuge.
========================================
The question is:
was what I wrote ""utter nonsense"
or is it "utter nonsense" to spend billions of dollars
trying to rationalize General Relativity?
Note that General Relativity wastes time, money and minds
on such pursuits as time travel, worm holes, space warps,
the beginning and end of the universe, and the mind of God,
and wastes billions of the taxpayers dollars on hyping
General Relativity and conducting experiments,
whereas no taxpayer money is spent hyping the DNA model
nor are multi billion dollars experiments conducted to
verify the model, although it is used ever day
to improve health, fight crime, improve food crops,
reconstruct history, etc.
The following two URL's provide some insight into the
value of Gravity Probes A and B.
http://www.thespacereview.com/article/132/1
Just about every space scientist will agree that Gravity Probe-B is a survivor. Scheduled for launch from Vandenberg Air Force Base on Monday atop a Delta 2 rocket, it will orbit 400 miles over the Earth's poles and test Einstein's General Theory of Relativity. However, it already has cost $700 million-$300 million more than originally estimated and nearly as much as both of NASA's Mars rovers combined-and is four years late. The stubborn little spacecraft has survived numerous hardware setbacks and delays and congressional scrutiny that should have killed it years ago. One astronomer on a different NASA space science program-who for obvious reasons wishes to remain anonymous-has joked that the Stanford University scientists who built the probe's instruments either have amazing political skills, or are somehow blackmailing members of Congress, because they have miraculously survived significant problems and cost overruns.
http://en.wikipedia.org/wiki/Gravity_Probe_A
"The clock rate was measured from the ground by comparing the microwave signal from the clock to a maser on the ground and subtracting a signal from the spacecraft that measured the Doppler shift. The clock rate was measured for most of the duration of the flight and compared to theoretical predictions. The stability of the maser permitted measurement of changes in the rate of the maser of 1 part in 1014 for a 100-sec measurement.
The experiment was thus able to test the equivalence principle.
Gravity Probe A confirmed the prediction that gravity slows the flow of time.."
Note that the excerpt about Gravity Probe A claims that the experiment confirmed
that "gravity slows the flow of time", when what the probe proved
is what Galileo discovered over 400 years ago,
and that is that acceleration affects the frequency of an oscillator.
It is interesting to see that the General Relativity Gurus pretend to possess powerful
esoteric knowledge, yet all are on the taxpayer dole,
and all reap royalties from selling books on General Relativity,
rather than from producing goods and services for the folks who pay the bills.
A mind is a terrible thing to waste.
--
Tom Potter
http://tdp1001.spaces.live.com/
http://www.tompotter.us/misc.html
http://www.geocities.com/tdp1001/index.html
http://notsocrazyideas.blogspot.com
http://www.flickr.com/photos/tom-potter/
http://tdp1001.wiki.zoho.com
http://groups.msn.com/PotterPhotos
http://www.androcles01.pwp.blueyonder.co.uk/dingleberry.htm
E
Eric Gisse
[snip]
GPS works. Stop whining.
You post thousands and thousands of words about this, and noooooobody
cares.
GPS works. Stop whining.
You post thousands and thousands of words about this, and noooooobody
cares.
S
Sam Wormley
Tom said:It is interesting to see that the General Relativity Gurus pretend to possess powerful
esoteric knowledge, yet all are on the taxpayer dole,
and all reap royalties from selling books on General Relativity,
rather than from producing goods and services for the folks who pay the bills.
Potter is on the taxpayer dole. Potter habitually disparages
physics that he fails to understand.
There once was a feller named Potter
Who's physics -- a bit of a rotter
He sputtered and roared
Most others got bored
He grasps relativity, Notter
Relativistic Effects on Satellite Clocks
http://relativity.livingreviews.org/open?pubNo=lrr-2003-1&page=node5.html
http://relativity.livingreviews.org/Articles/lrr-2003-1/frctfrq.png
Hey, Potter, GTR has directly contributed to a $30B+ GPS industry,
benefiting people all over the world. Aviation, shipping, asset
management, survey, mining, agriculture, time dissemination,
communications networks... and on and on!
Bluster on, Potter, bluster some more! Froth at the mouth! Whatever!
T
Tom Roberts
Sue... said:What is the Lorentz force on the muons of
the experiment?
Look it up. Don't expect me to do your homework for you.
You spend lots of time posting irrelevant links around here, why not
spend a few minutes looking up something relevant to your own question?
Tom Roberts
S
Sue...
Look it up. Don't expect me to do your homework for you.
You spend lots of time posting irrelevant links around here, why not
spend a few minutes looking up something relevant to your own question?
I am not the custodian of an experiment list
so have no reason to care how it might be
viewed by viewed by others.
http://arxiv.org/abs/quant-ph/0206164
I just thought you might know offhand which
of the ~time-dilation~ experiments were
conducted in the absence of both gravitational
and Lorentz forces.
Sue...