A Question for Relativists

Discussion in 'Physics & Math' started by MacM, Jan 14, 2005.

?

Is SRT only correct as to Gamma for an Absolute Relative Velocity and not Relative '

  1. Yes

    2 vote(s)
    100.0%
  2. No

    0 vote(s)
    0.0%
  1. 2inquisitive The Devil is in the details Registered Senior Member

    Messages:
    3,181
    by MacM:
    Ronald R. Hatch:"But these statements are patently untrue of GPS. It may appear to be a subtle difference, but it is very important to note that the GPS satellites' clock rate and the receiver's clock rate are not adjusted as a function of their velocity relative to one another. Instead, they are adjusted as a function of their velocity with respect to the chosen frame of reference—in this case the earth-centered, non- rotating, (quasi) inertial frame."

    Emphasis added by MacM.

    Now GR clearly has a many factor affect over velocity at this range but I think it would be hard for you to explain why the velocity calculation I did matches the calibration cited by the manufacturer if it were not true.
    ===============================================================

    No Mac, it is not hard for me to explain at all. I have repeatedly linked to the true preset
    adjustment on the clocks in this and other threads. Have you forgotten, or did you just
    not understand what was being said? You fail to understand what is stated in the cut
    & paste above. He did NOT state 7.2 microseconds were being deducted from the tick
    rate of the satellite clocks. He stated they were adjusted with reference to the chosen
    Earth-centered, NON-ROTATING, (quasi), inertial reference frame. In that (quasi) frame
    of reference, their is no relative velocity between the Earth's center and the satellites,
    thus no adjustment to the tick rate in the clocks. It is a 'artificial' frame of reference in which the satellites do not move in relative to the Earth's center.
     
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  3. MacM Registered Senior Member

    Messages:
    10,104
    He does state they are so adjusted. He does not state the amount. The HP Application Note 1272 however, states clearly there is a 7.2 micro-second velocity adjustment.

    If you would be so kind as to post your source once again I'll take another look. But at this point I do not see that you have shown 7.2 micro-seconds is not the correct velocity adjustment.
     
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  5. 2inquisitive The Devil is in the details Registered Senior Member

    Messages:
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    http://relativity.livingreviews.org/Articles/lrr-2003-1/node5.html

    You have to read the page Mac, and many others to get a clear understanding of what
    is happening. The clocks are adjusted to run 44.647 microseconds per day slow to
    offset garvitational frequency shifts. That is essentially what GR predicts. However,
    there is NO 7.2 microseconds deducted from that figure as stated on many university
    websites. They say the adjustment is about 37.5 to 38 microseconds, which is what
    would be true IF the 7.2 m/s were deducted from the gravitational effects.
     
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  7. 2inquisitive The Devil is in the details Registered Senior Member

    Messages:
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    Here is a cut and paste describing the results of those initial satellite clock rates before GPS system was implemented. The frequency preset has been increased a
    little since then, not decreased.
    "There is an interesting story about this frequency offset. At the time of launch of the NTS-2 satellite (23 June 1977), which contained the first Cesium atomic clock to be placed in orbit, it was recognized that orbiting clocks would require a relativistic correction, but there was uncertainty as to its magnitude as well as its sign. Indeed, there were some who doubted that relativistic effects were truths that would need to be incorporated [5]! A frequency synthesizer was built into the satellite clock system so that after launch, if in fact the rate of the clock in its final orbit was that predicted by general relativity, then the synthesizer could be turned on, bringing the clock to the coordinate rate necessary for operation. After the Cesium clock was turned on in NTS-2, it was operated for about 20 days to measure its clock rate before turning on the synthesizer [11]. The frequency measured during that interval was +442.5 parts in compared to clocks on the ground, while general relativity predicted +446.5 parts in . The difference was well within the accuracy capabilities of the orbiting clock. This then gave about a 1% verification of the combined second-order Doppler and gravitational frequency shift effects for a clock at 4.2 earth radii."

    You will notice that the difference in tick rates was NOT 38 microseconds per day.
    I have read this same report at several places, not just Dr. Ashby's site.
    http://relativity.livingreviews.org/Articles/lrr-2003-1/node5.html
     
  8. MacM Registered Senior Member

    Messages:
    10,104
    I'm not sure but what you seem to be doing some selective reading. There may or may not be bad information out there on various sites. But you should consider that your own link (on another page) says this.

    ***************** Extract from Niel Ashby's Article **********
    Figure 2 shows the net fractional frequency offset of an atomic clock in a circular orbit, which is essentially the left side of Eq. (35) plotted as a function of orbit radius a, with a change of sign. Five sources of relativistic effects contribute in Figure 2. The effects are emphasized for several different orbit radii of particular interest. For a low earth orbiter such as the Space Shuttle, the velocity is so great that slowing due to time dilation is the dominant effect, while for a GPS satellite clock, the gravitational blueshift is greater.
    ***************************************************

    You seem to be argueing that there is no velocity affect. That is in conflict with your own source. He didn't say the magnitude but he simply said GR was "Greater" for the GPS. Further that Velocity affect and gravity affect cancel at around 9,500 miles I think. I didn't write it down.
     
    Last edited: Jan 24, 2005
  9. 2inquisitive The Devil is in the details Registered Senior Member

    Messages:
    3,181
    by MacM:


    "Now GR clearly has a many factor affect over velocity at this range but I think it would be hard for you to explain why the velocity calculation I did matches the calibration cited by the manufacturer if it were not true."
    =============================================================

    No Mac, you are clearly waffling, changing the context of your assertion. I have also
    read and posted quotes from Dr. Ashby in the past where he stated the time offset
    due to relative velocity was handled during the handshaking phase between satellite
    clock and GPS reciever. The time synch phase, which you keep ignoring. Now support
    your assertion that a 7.2 microsecond offset is handled by a prelaunch adjustment.
     
  10. MacM Registered Senior Member

    Messages:
    10,104
    Look, I'm not keen on argueing with you. Hatch says one thing and Ashby says something different - (But you didn't respond to the other things Ashby also says see above).

    Now, care to explain about what you mean about me waffeling. I have made no changes in my position. Where is the waffel?

    However, I have posted HP's Application Note 1272. They manufacture GPS equipment. I take their word over either of the other two and if we collective consider these three 2 are clear on the subject and your source seems to say things you deny.

    You must respond to my above post on Ashby's comments about the velocity affect on clocks. That actually makes it three for three that you are somehow mistaken about "No Velocity Affect".
     
  11. 2inquisitive The Devil is in the details Registered Senior Member

    Messages:
    3,181
    Mac, you have posted links to Hatch's Lorentz Ether Theory website and to the ION.
    You have posted no links to any manufacturers website. What exactly does HP's
    Application Note 1272 state? I have never seen it before. Who is HP and what GPS
    equipment do they make? You are waffling because you cannot support your assertion.
    You stated that a 7.2 microsecond adjustment was preset into the satellite clocks
    before launch, among other things. I know it is not true, I asked you to support it.
    You have failed to do so, waffling all over the place, as usual.
     
  12. MacM Registered Senior Member

    Messages:
    10,104
    1 - I think you have missed the fact that these numbers are not in micro-seconds/day.

    2 - If this was the first attempt to measure such affects what was the comparative accuracy of the test.

    3 - The data appears to be collective velocity and gravity. Just how does this show no veloicty affect?
     
  13. 2inquisitive The Devil is in the details Registered Senior Member

    Messages:
    3,181
    1. I missed nothing Mac. Do you think those figures represent 38 microseconds per day?
    2. comparative accuracy of the test in relation to what? They used cesium
    clocks.
    3. Can you show where 7.2 microseconds per day is indicated for for 'velocity
    effects'?
    No, Mac, the post of yours you keep linking to as some sort of triumph is
    'moot'.
     
  14. MacM Registered Senior Member

    Messages:
    10,104
    When I first saw this I got the impression you are attempting to goad me into some response, which I will not do. However, I now see that unbelievably I failed to actually post the link to the manufacturers application note.

    http://icapeople.epfl.ch/noro/papers/database/paper81/

    Now, how is it that you think you know it isn't true.?

    Why do you assert I am waffeling "as usual" when I am not and do not?

    Also, you have failed to resond to the information I have pointed out in your own sources?

    BTW Hatch became an ether theorist mainly due to his experience with GPS.
    I think. Those here refer to him as a Crackpot. But I have seen many supportive papers by those that have worked on GPS with him. They say he is no Crackpot.


    But surely you respect HP's data sheet. They are a GPS equipment manufacturer.
     
    Last edited: Jan 24, 2005
  15. MacM Registered Senior Member

    Messages:
    10,104
    I have no idea what they represent. It is a change of 4 out of 445+ of something. Far to large to be a relavistic adjustment of any kind I can think of.

    But the first clocks were how accurate compared to current in GPS use?

    Done above.

    Hardly.

    Please Register or Log in to view the hidden image!

    Yuriy's method V3 (relative velocity) produces an incorrect dilation. i.e 5.58 micro-seconds/day vs 7.2. 7.2 is the correct answer for the absolute velocity of orbit and not relative veloicty between clocks.
     
  16. 2inquisitive The Devil is in the details Registered Senior Member

    Messages:
    3,181
    OK, l was of of town again yesterday, and I have been delaying answering your posts
    partially because it is so time consuming to go through everything and show where my
    thoughts originate. GPS is a very complicated system, Mac, especially for people such
    as you and I with no great math knowledge. It is even very complicated to understand
    for physicists with great math knowledge because the details of the system itself are
    not completely understood. They are interpreted in different ways. Dr. Ashby's papers
    are the ones sited by the operators of the system, the US Navel Observatory. But, his
    approach is a fill-in-the-blanks one, like everyone else's. Scientifically, and according
    to the makers of the satellite clocks, they are adjusted for frequency shifts before
    launch, not to run slow by X number of microseconds per day. Of course, frequency
    shifts correspond to time rate changes, but I am unable to do the calculations or to
    find links where they are done. The website you linked to above is not from a satellite
    clock manufacturer. It is to a paper written at a tech school in Switzerland, probably
    by one of the students, because the author is not on the present or past faculty. I
    speculate it was written for HP's advertising literature from what I read. Hewlett-Packard
    used to build someting called a 'SmartClock', used mostly in electronic gadgets. It contained a chip built by Motorola that interfaced with the GPS clocks for accurate
    clock rates in the equipment, the same chip used in the 'ON STAR' system in cars. It
    had nothing to do with the satellite clock adjustment itself, other than a reference to
    the same thing that is written in many college textbooks. That is the problem. The
    satellite clocks are adjusted to beat at a lower frequency before launch by the rate
    of 4.4647 * 10^10, or as I understand it, about 446 parts per billion. I do not know
    how many microseconds per day this equates to. I thought I had a good idea, but it
    seems I may have been wrong. I had seen these quotes earlier and may have drawn
    the wrong conclusion. Cut & paste from Dr. Ashby's papers:
    "Since all clocks at rest on the geoid beat at the same rate, it is advantageous to exploit this fact to redefine the rate of coordinate time. In Eq. (12) the rate of coordinate time is defined by standard clocks at rest at infinity. I want instead to define the rate of coordinate time by standard clocks at rest on the surface of the earth. Therefore, I shall define a new coordinate time t'' by means of a constant rate change:

    (NOTE: the equations do not copy)

    The correction is about seven parts in 10^10 (see Eq. (18))."
    http://relativity.livingreviews.org/Articles/lrr-2003-1/node3.html
    All the calculations did not copy, but I interpreted this to mean that 7 microseconds
    was about equilivent to a change in frequency of about 7 * 10^10. I thought the
    preset was about 44.647 * 10^-10 in frequency, so I assumed that was about -44.6
    microseconds. But something is wrong. When I looked closer, the prelaunch frequency
    offset is 4.4647 * 10^-10. Now I am confused even further because seem to indicate
    only a 4.46 microsecond difference, and I know that can't be correct. The main point
    is, the factory frequency preset on the clocks is very close to the frequency variation
    predicted by General Relativity for gravitational blueshift only. There are many other
    relativistic adjustments considered though, so I don't know what fraction the relative
    velocity adjustment amounts to of that total. But the 7.2 figure seems to come from
    college websites rather than actual observed results. Again the predictions and actual
    measured results from presystem tests:
    "After the Cesium clock was turned on in NTS-2, it was operated for about 20 days to measure its clock rate before turning on the synthesizer [11]. The frequency measured during that interval was +442.5 parts in 10^12 compared to clocks on the ground, while general relativity predicted +446.5 parts in 10^12. The difference was well within the accuracy capabilities of the orbiting clock. This then gave about a 1% verification of the combined second-order Doppler and gravitational frequency shift effects for a clock at 4.2 earth radii."
    I may be mistaken, but I interpreted that as meaning GENERAL RELATIVITY predicted
    +446.5 parts in 10^12 alone, not to include Special Relativity effects. That is essentially what clocks are preset for NOW before launch. This information is available
    at many websites, including in papers linked to from the USNO's website. Don't get me
    wrong, I am not saying that I believe there ISN'T a relative velocity effect, just that
    I don't think anyone actually knows EXACTLY how much it is.
     
  17. MacM Registered Senior Member

    Messages:
    10,104
    2Inquisitive,

    I read the part about "General Relativity" the same as you do. However, the figures: 442.4/1E12 = 38.232 micro-seconds/day. (actual measured number)

    The amount claimed as General Relativity of 446.5/1E12 = 38.5776 micro-seconds/day.

    I'm thinking this paper may infact be a typo and they meant collectively the Relativity affect, not just General Relativity.

    38.5776 + 7.2 = 45.776 micro-seconds/day.

    That is GR is supposed to be 45 micro-s/day and Velocity affect 7. So it would fit if the word "General" were not in that sentance.

    Thanks for your information in any case. I'm going to do some more research on this as well.

    Perhaps one of the professionals here would like to say what GR should be, that would clear this up.

    446.5/1E12 = 4.465E-10: 4.465E-10 * 24 * 3,600 = 3.85776E-5 = 38.5776E-6
     
    Last edited: Jan 26, 2005
  18. MacM Registered Senior Member

    Messages:
    10,104
    2Inquisitive,

    I appears my hunch may be correct. The following is also written by Ashby.

    *************************** Extract *********************
    http://www.phys.lsu.edu/mog/mog9/node9.html
    Relativistic effects on satellite clocks can be combined in such a way that only two corrections need be considered. First, the average frequency shift of clocks in orbit is corrected downward in frequency by 446.47 parts in 10<sup>12</sup> . This is a combination of five different sources of relativistic effects: gravitational frequency shifts of ground clocks due to earth's monopole and quadrupole moments, gravitational frequency shifts of the satellite clock, and second-order Doppler shifts from motion of satellite and earth-fixed clocks.
    ******************************************************

    It appears indeed there is a 7.2 micro-second motion adjustment which only fits the description I posted. That 446 number you posted is actually a collective affect value, not just GR.
     
    Last edited: Feb 7, 2005
  19. MacM Registered Senior Member

    Messages:
    10,104
    Last edited: Jan 26, 2005
  20. 2inquisitive The Devil is in the details Registered Senior Member

    Messages:
    3,181
    Your last source does seem like it is a good one, Mac. My earlier doubts about exactly
    7.2 microseconds per day due to velocity is also shown in this link with another article
    by Dr. Ashby. He specifically states that GPS clocks run slow by 6 millionth of a second
    per day due to SR effects and run fast by 45 millionth of a second per day due to GR effects. It is one of the reasons why I speak of an uncertainty about the exact amount due to velocity. Your source seems good, but how can the effect be measured
    exactly? It can only be calculated, only the total offset is known and even that is
    further adjusted during the clock synch phase between satellite and reciever.
    http://physics.syr.edu/courses/PHY312.03Spring/GPS/GPS.html
     
  21. MacM Registered Senior Member

    Messages:
    10,104

    I would agree that the realm being dealt with is extremely small but due to the stability of atomic clocks seems to provide sufficient data when accumulated over time so as to make the verification of the mathematics and theories highly testable. Direct measure certainly is currently beyond our means.

    The following excerpt should clarify precisely what values are being looked at as opposed to those that have attacked my understandings:

    ************************** Extract ***********************
    One of the effects of Einstein’s Special Relativity theory is time dilation. Clocks moving with high velocity run slower then clocks with the smaller relative velocity. Therefore, clocks in the GPS satellites will run slower compare to the clocks on the Earth because GPS satellites have a large velocity.
    *******************************************************

    My view: [post=752958]Here[/post]

    The issue of concern for me is the tendancy of Relativists to take the functioning of GPS and to then make the claim it proves Special Relativity when in fact Special Relativity is not being applied. Only components used in Special Relativity are used but those components are those which describe Lorentz Relativity.

    To call this proof of Special Relativity requires that you disregard the tenants of SRT. It is a narrow view of reality where the "Relative Velocity" is as I stated bifurcated. V1 being the orbit velocity to the earth's axis as a local preferred rest referance frame and the earth's rotational velocity (V2) at the surface and such clocks relative gamma to the same common rest frame.

    This process is not Special Relativity. It is Lorentz Relativity. As I showed in my post using Special Relativity where motion is declared between clocks V3 = (V1 - V2) FAILS. Further the use of a local preferred rest frame precludes the claim by SRT that either observer can be declared as being at rest. That fact resolves the reciprocity issue I have yelled about for so long.

    GPS clearly shows the Lorentz Gamma function is valid but Einstein's concept of it's application as Special Relativity is invalid.

    Failure of Relativists to recognize that is simply further damaging the furture development of physics. SRT should be abandoned and more effort made to understanding the Gamma function.

    Thanks for your paticipation.
     
    Last edited: Feb 7, 2005
  22. 2inquisitive The Devil is in the details Registered Senior Member

    Messages:
    3,181
    I found another article that appeared in Physics Today in 2003 by Dr. Ashby. It is the best yet for understanding GPS and how it is set up. Mac, in your example you are
    posting, you are only considering one frame of reference to arrive at your 7.2 m/s
    figure. However, GPS is not set up that way. Remember when I was speaking of the
    non-rotating inertial ECI frame of reference earlier and Yuriy said the Earth's surface
    had to rotate, day/night was what he used. Well it doesn't. Dr. Ashby explains the frame in greater detail in this recient article. One end of the frame is the center of the
    Earth and the other is the FIXED STARS. The Earth surface does not rotate in this artifical frame, but the GPS satellites do orbit the Earth. It is the frame where the
    synchronization of clocks take place, and where the initial satellite velocity is calculated with reference to the non-rotating Earth, the same calculations where you
    produce 7.2 m/s. HOWEVER. The ECI frame is only one frame, there is also the ECEF
    frame. THAT frame is where the Earth's surface does rotate. Calculations are also made in it to account for the difference in satellite to Earth surface velocity. In effect,
    the satellites velocity is calculated twice, one wrt a non-rotating surface (ECI) and
    then in the rotating frame (ECEF) where the surface speed of the Earth is deducted
    from the 7.2 m/s calculated in the ECI frame. The ECI frame is used to synchronize clocks, eliminating other effects such as the Sagnac effect, the lense-Thirring effect,
    the Thomas procession AND as a frame in which the speed of light is constant. The
    speed of light is NOT constant in a rotating frame of reference because it does not
    travel a straight path, it spirals. All these effects I just mentioned are THEN taken into
    account in the ECEF frame of reference and individual satellite clocks are steered to
    account for them. Even moving a satellite clock from one orbit to another changes its
    frequency beat and must be adjusted for. In sum, yes the satellite clocks do reflect
    the sat clock to Earth surface time dilation, not just a total velocity effect. A link which is slow to download on my computer, a pdf:
    http://web.ccr.jussieu.fr/tarantola/Files/Professional/GPS/Neil_Ashby_Relativity_GPS.pdf
     
  23. MacM Registered Senior Member

    Messages:
    10,104
    2Inquisitive,

    I would like to see that information. But my computer has problems with pdf, on this jparticular one I get a black page and can read nothing, usually I read all but some formula or drawings, etc. Can you re-post it if they have an HTML version also?

    In my presentation I did allow for earth's surface velocity in the same pole rest frame but the magnitude even at the equator only results in time dilation figures in the Pico-Seconds/day loss and did not alter the 7.2 micro-second figure.

    I would like to see more how they are working that motion in. It still appears to be non-SRT or not direct relative velocity between clocks.
     

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