"GSS" <gurcharn_sandhu@xxxxxxxxx> wrote in message
> George Dishman wrote:
>> "GSS" <gurcharn_sandhu@xxxxxxxxx> wrote in message
>>> The original station times in the ATDF records are
>>> referred to Coordinated Universal Time (UTC). When computing Earth
>>> rotation and orientation quantities, the Terrestrial Dynamical Time
>>> (TDT) timescale is used. Conversion between the UTC, TDT and TDB
>>> timescales is straightforward using standard practices."
>> Again, they are converting between frames.
> That is "When computing Earth rotation and orientation quantities".
Not just that, there are conversions between atomic time
and UTC involved so it needs care, and you also have to
consider the effect of the variation of the gravitational
potential of the Earth relative to the Sun because of
gravitational red shift, but these are fairly esoteric
points so let's not get bogged down again.
>>> No, I still don't see why you demanded that "provided the measuring
>>> apparatus is at rest in the frame in which A and B are moving"
>> OK, let me see if I can make it clearer. Here is
>> your diagram:
>>> ----->V1 ----->V1
>> If point A is the DSN and point B is Pioneer,
>> in which frame are we working such that point
>> A has a velocity of V1?
> Just for illustration we have assumed that 'A' is DSN type ground
> station and 'B' is Pioneer type spacecraft. For the sake of simplicity
> of arguments, we have assumed that both A and B are separated by a
> distance D of about 40 AU and are moving with 'same' uniform velocity
> V1 = 30 km/s in the ICRS or SSBF.
Sure. In practice Pioneer's speed is 12km/s but the actual
value isn't significant when considering the method.
>>>> In reality the measurements
>>>> are made in the frame of the DSN site antenna. What
>>>> you would need to do is transform the measurements
>>>> from that frame to the ICRF (or whatever) and to do
>>>> that you need transform equations. That is where
>>>> the problem lies - which do you use, Galilean or
>>> There is absolutely no problem whatsoever.
>>> Let us focus on our specific illustrative example where precision time
>>> Ta_t is measured with atomic clock at A, Tb_r and Tb_t are measured
>>> with atomic clock at B and finally Ta_r is again measured with atomic
>>> clock at A. Then we compute the signal propagation,
>>> Uplink time Tu = Tb_r - Ta_t .... (A1)
>>> Downlink time Td = Ta_r - Tb_t .... (A2)
>>> These atomic time measurements are absolute and can be automatically
>>> recorded in the computer data. It is up to the user whether to use this
>>> timing data in Barycentric Celestial Reference Frame or the Galactic
>>> Celestial Reference Frame.
>> No, you said the first clock was at A so it is
>> measured in the DSN site frame, not the SSBF or
>> a galactic frame. Your next step would be to
>> transform your DSN measure to the SSBF, but how
>> are you going to do that?
> This is the crucial issue which points to the divergence of our
> viewpoints. Let me elaborate on this.
> We assume that the rate precision and synchronization accuracies of the
> two atomic clocks are as 'perfect' as modern technology would permit.
OK. That may still not be good enough for what you want
to do and a synchronisation scheme gets even messier but
in fact I think you can use the total round-trip time to
get your answer anyway so again let's push on.
> In my opinion whenever a certain event 1 triggers a time readout t1
> from an atomic clock, this time t1 recorded in the computer data *must*
> be considered an absolute value, valid in all *celestial* reference
Not "must be" but "is assumed to be". Your analysis is based
on making a prediction using Galilean relativity in which
that assumption is valid as a way of testing the hypothesis
that Galilean relativity applies.
> Since the proposed experiment is intended to be used for refuting the
> validity of relativity theories, logically we must not use the
> provisions of these relativity theories to modify the value of these
> time readouts t1 or t2 etc.
That is absolutely correct, since you are testing the Galilean
hypothesis, you must use that for your prediction.
>>> The solar system
>>> as a whole is known to be moving in the Galactic Celestial Reference
>>> Frame at a velocity of U1 = 220 km/s. From the above mentioned timing
>>> data, this velocity can be computed as shown earlier, by the relation,
>>> Velocity = c*(Tu-Td)/(Tu+Td) ...... (A3)
>>> where c is an isotropic constant speed of light propagation in the
>>> Celestial Reference Frame under consideration. Now, in actual
>>> experiment if the measured timing data Tu and Td are such that the
>>> velocity obtained from equation A3 above, yields a value of the order
>>> of 30 km/s it will imply that the speed of light propagation is an
>>> isotropic constant in the BCRF as is generally being assumed.
>> That is not what is generally assumed.
>>> On the
>>> other hand if the measured timing data Tu and Td are such that the
>>> velocity obtained from equation A3 above, yields a value of the order
>>> of 250 km/s it will imply that the speed of light propagation is an
>>> isotropic constant in the Galactic Celestial Reference Frame. However,
>>> if the measured timing data Tu and Td are such that the velocity
>>> obtained from equation A3 above, yields a value of the order of 400
>>> km/s or above, it will imply that the speed of light propagation is an
>>> isotropic constant in the Universal or Absolute Celestial Reference
>>> There is only one *extremely unlikely* situation when Tu = Td, which
>>> will confirm the SR postulate that speed of light propagation is an
>>> isotropic constant in *all* celestial reference frames.
>>> Isn't it an exciting test of relativity theories as well as for
>>> detecting the Universal or Absolute Reference Frame?
>> No, it is just the Michelson-Moreley experiment.
>> It's been done many times.
> As I explained earlier, MM experiment was not based on the precise
> timing measurements with modern atomic clocks.
And as I explained, the second arm provides the precise
time reference. If you want an even more direct equivalent
where signals are timed with atomic clocks then the GPS
system does that.
> Even though MMX was
> intended to detect Absolute Reference Frame and failed. For instance,
> the Pioneer anomaly is now being extensively debated and we are living
> with the situation when proper explanation for this anomaly has still
> not been found.
Indeed, now that _is_ fascinating, but an absolute frame
would not explain it. The effect is a frequency error
which grows linearly with time. The characteristics are
not what anisotropy of the speed would produce.
> In my opinion, the failure of MMX needed to be
> extensively debated to ascertain the proper cause of its failure.
In my opinion, it didn't fail. It gave us an accurate
if surprising result but it has been confirmed many
times in many different ways since then.
> then we should have 'lived with' the situation as an unexplained
But the result _has_ been explained, and that explanation
has been the basis of most modern science. A large amount
of the technology we rely on simply wouldn't work if it
> Instead, by jumping to the invalid conclusion regarding
> isotropy of speed c of light in all inertial reference frames, all
> efforts to seek correct explanation for the failure of MMX were
> abandoned. In this regard let me refer you to an alternative
> explanation for the failure of MMX.
So does that also explain the Ives-Stilwell experiment?
what about GPS which relies on the actual time of
propagation exactly as in your suggested experiment?
You see the problem is that if you want to propose a
new theory, you have to get it to cover all the existing
known results, not just one.