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Talk:Counterexamples to Relativity (view source)
Revision as of 13:34, August 14, 2010
, 13:34, August 14, 2010→Reversion of my edit: @aschlafly and @ed poor
:Now, it's interesting that the first builders considered relativity, but what our readers want to know is whether they decided that it made a big enough difference. --[[User:Ed Poor|Ed Poor]] <sup>[[User talk:Ed Poor|Talk]]</sup> 11:52, 13 August 2010 (EDT)
:Now, it's interesting that the first builders considered relativity, but what our readers want to know is whether they decided that it made a big enough difference. --[[User:Ed Poor|Ed Poor]] <sup>[[User talk:Ed Poor|Talk]]</sup> 11:52, 13 August 2010 (EDT)
::*''don't be rude'' sorry, but please don't mistake my exasperation for rudeness!
::*''The question is whether relativistic effects are (A) big enough to matter or (B) actually being calculated and compensated for by any major GPS. '' The answer to (A) as well to (B) is a very emphatic '''yes'''. It was given repeatedly and can be found in the source linked above - or in the section of this very talk page to which I linked in my edit-comment (conveniently repeated a couple of lines above, too). But to spare you the work of actually scrolling backwards, here it is again:
::::[http://www.navcen.uscg.gov/pubs/gps/sigspec/gpssps1.pdf Global Positioning System Standard Positioning Service Signal Specification], 2nd edition, June 1995:
::::p. 13: ''To compensate for relativistic effects, the output frequency of the satellite's frequency standard -- as it would appear to an observer located at the satellite -- is 10.23 MHz offset by a Df/f = -4.4647 x 10<sup>-18</sup> or a Df = -4.567 x 10<sup>-3</sup> Hz.''
::::p. 39: ''The coefficients transmitted in subframe 1 describe the offset apparent to the control segment two-frequency receivers for the interval of time in which the parameters are transmitted. This estimated correction accounts for the deterministic satellite clock error characteristics of bias, drift and aging, as well as for the satellite implementation characteristics of group delay bias and mean differential group delay. Since these coefficients do not include corrections for relativistic effects, the user's equipment must determine the requisite relativistic correction. Accordingly, the offset given below includes a term to perform this function.''
::*This ''Global Positioning System Standard Positioning Service Signal Specification'' is quoted on the talk-page of the article for the [[GPS]], too. It is the relevant document for everyone - engineer of physicist - who wants to work with the signals of the GPS.
::*This quote alone shows that the statement ''Contrary to the claims of Relativists, the GPS system has never been based on Relativity.'' is wrong. Plain and simple.
::*Effects on the GPS became a textbook example for relativity, see e.g., [http://www.colorado.edu/physics/Web/directory/faculty/ashby_n.html Neil Ashby], who writes in [http://relativity.livingreviews.org/open?pubNo=lrr-2003-1&page=title.html Relativity in the Global Positioning System]:
::::''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! 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. The frequency measured during that interval was +442.5 parts in 10<sup>12</sup> compared to clocks on the ground, while general relativity predicted +446.5 parts in 10<sup>12</sup>. 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. ''
::*But you don't have to take this secondary source at face value, you can go to the primary source: [http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA058591 Initial Results of the NAVSTAR GPS NTS-2 Satellite], Naval Research Lab Washington, D.C., 25 May 1978 (Full text: [http://www.leapsecond.com/history/1978-PTTI-v9-NTS-2.pdf pdf]). '''Ever since 1978, relativistic effects are observed and compensated in various ways.''' Or as the abstract states it:
::::''NTS-2 was successfully launched on 23 June 1977 into a near 12-hour circular orbit. Precise frequency and timing signals are derived from the two cesium frequency standards. '''This paper discusses the launch and preliminary results which include verification of the relativistic clock effect.''' ''
::*PhyllisS introduced the following quote above:
::::''The Time Service Department – a department of the U. S. Navy - states: “The Operational Control System (OCS) of the Global Positioning System (GPS) does not include the rigorous transformations between coordinate systems that Einstein’s general theory of relativity would seem to require – transformations to and from the individual space vehicles (SVs), the Monitor Stations (MSs), and the users on the surface of the rotating earth, and the geocentric Earth Centered Inertial System (ECI) in which the SV orbits are calculated. There is a very good reason for the omission: the effects of relativity, where they are different from the effects predicted by classical mechanics and electromagnetic theory, are too small to matter – less than one centimeter, for users on or near the earth.”''
:::This is taken from a text of ''Henry F. Fliegel'' and ''Raymond S. DiEsposti''from December 1996 who are talking about ''another'' relativistic effect than the ones already implemented. Please keep in mind that the Specification above is from June 1995! Only someone who didn't read the text - or didn't understand it - could abuse this quote to invoke the impression that no effects of relativity were implemented in the GPS.
::*Of course, the information above may be ignored - as it was previously: ''tl;dr''. But actively ignoring facts which contravene a statement just to repeat the statement is a behavior which can only be described in a rude way.
[[User:RonLar|RonLar]] 09:34, 14 August 2010 (EDT)
==My Great-grandfather==
==My Great-grandfather==