[ExI] The most accurate clock ever

spike at rainier66.com spike at rainier66.com
Sat Dec 1 16:42:54 UTC 2018



From: extropy-chat <extropy-chat-bounces at lists.extropy.org> On Behalf Of John Clark
Subject: Re: [ExI] The most accurate clock ever


On Thu, Nov 29, 2018 at 11:57 AM <spike at rainier66.com <mailto:spike at rainier66.com> > wrote:


>> John just a coupla comments please.  The time error measurement is (as I recall) a consequence of Special Relativity rather than General Relativity


>..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…


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.


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.


>…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.


 John K Clark



Agreed, c^2 is difficult to overcome when it works against you.



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