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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><b>From:</b> extropy-chat <extropy-chat-bounces@lists.extropy.org> <b>On Behalf Of </b>John Clark<br><b>Subject:</b> Re: [ExI] The most accurate clock ever<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal><span style='font-family:"Arial",sans-serif'>On Thu, Nov 29, 2018 at 11:57 AM <<a href="mailto:spike@rainier66.com">spike@rainier66.com</a>> wrote:<o:p></o:p></span></p></div><div><div><p class=MsoNormal><o:p> </o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span class=gmaildefault><i><span style='font-family:"Arial",sans-serif'>>> </span></i></span><i>John just a coupla comments please. The time error measurement is (as I recall) a consequence of Special Relativity rather than General Relativity</i><o:p></o:p></p></div></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><span style='font-size:14.0pt'>>..Actually in this case General Relativity makes a larger contribution than Special Relativity, it's one of the few examples where it does something practical. The GPS satellite is moving very fast so due to Special Relativity the satellite's clock will LOSE 7210 nanoseconds a day, but the satellite's clock is more distant from the Earth's center so it's in a weaker gravitational field than the clock on the ground, so due to General Relativity the clock will GAIN 45,850 nanoseconds a day. Taking these 2 factors into account the satellite's clocks gains 45,850 −7,210 = 38,640 nanoseconds a day relative to a clock on the ground. If this were not taken into account the GPS system would drift off by 6 miles each day every day and soon become useless…<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>John, a satellite isn’t a plane landing on a deck. We might be talking two completely different things here. The gravitational influence of the carrier could perhaps create a general relativity related frame dragging effect, but the electromagnetic presence of that big hunk of steel would be orders of magnitude larger and easier to use for that purpose. Modern carrier landings already use EM instruments in any case.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>Regarding the new clock, I can see how something like that could be used for space-based control systems however. We are always looking for ways to do long baseline interferometry, which definitely is influenced by the tiny gravitational anomaly effects.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>>…I think that huge c^2 factor would work against you in this case, even a gigantic amount of magnetic energy would correspond to a tiny amount of mass and a corresponding super small change in gravity, so small a change that even this clock probably couldn't detect it.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'> John K Clark<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>Agreed, c^2 is difficult to overcome when it works against you.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>spike<o:p></o:p></span></p></div></div></div></div></body></html>