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Talk:Counterexamples to Relativity (view source)
Revision as of 18:13, January 6, 2010
, 18:13, January 6, 2010→GPS revisited: new section
::[[User:FrankC|FrankC aka ComedyFan]] 12:02, 6 January 2010 (EST)
::[[User:FrankC|FrankC aka ComedyFan]] 12:02, 6 January 2010 (EST)
== GPS revisited ==
The same Tom von Flandern who is quoted in the article on the [[theory of relativity]] saying that the GPS programmers "have basically blown off Einstein", wrote in an article in 1998:
''So we can state that the clock rate effect predicted by GR is confirmed to within no worse than ±200 / 45,900 or about 0.7%, and that predicted by SR is confirmed to within ±200 / 7,200 or about 3%. This is a very conservative estimate. In an actual study, most of that maximum 200 ns/day variance would almost certainly be accounted for by differences between planned and achieved orbits, and the predictions of relativity would be confirmed with much better precision.''
As for how the satellites take into account the relativistic effects, here is his explanation of the so-called ''factory offset'' of the atomic clocks for the satellites:
''GPS atomic clocks in orbit would run at rates quite different from ground clocks if allowed to do so, and this would complicate usage of the system. So the counter of hyperfine cesium transitions (or the corresponding phenomenon in the case of rubidium atomic clocks) is reset on the ground before launch so that, once in orbit, the clocks will tick off whole seconds at the same average rate as ground clocks. GPS clocks are therefore seen to run slow compared to ground clocks before launch, but run at the same rate as ground clocks after launch when at the correct orbital altitude.''
Seems to me that relativistic effects have to be taken into account.
[[User:FrankC|FrankC aka ComedyFan]] 13:13, 6 January 2010 (EST)