Date: Wed, 14 Aug 2024 22:04:32 +0200
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Subject: Re: Space-time interval (2)
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W dniu 14.08.2024 o 21:53, Paul.B.Andersen pisze:
> Den 14.08.2024 00:42, skrev Richard Hachel:
>>
>> I just explained to you the synchronization used by GPS. 
> 
> You have no idea of how the GPS SV-clocks are kept synchronous.
> 
>> Abstract synchronization, but interesting to be able to use a 
>> universal present time plan (which does not exist in nature).
> 
> Quite.
> The "universal present time plan", namely
> the "Coordinated Universal Time" or "Temps Universel Coordonné",
> short UTC (not CUT or TUC - a compromise)
> is indeed a theoretical time defined by humans.
> ("It does not exist in nature", Good grief! :-D)
> 
> That it is coordinated simply means that UTC is the same at any point
> in the non rotating Earth centred frame of reference (ECI-frame).
> UTC's rate is defined by stationary clocks (as defined by SI) on
> the geoid. UTC is 12.00 when the mean sun is in the meridian
> at Greenwich.
> 
> You seem to think that what you call "a universal present time plan"
> has something to do with GPS. But UTC was created January 1, 1960,
> before the GPS.
> 
> The UTC was nothing new, before that was Greenwich Mean Time, GMT.
> GMT was the time shown by the pendulum clock at Greenwich,
> which was kept in sync with the mean solar day, and the second
> was defined by the mean solar day.
> The GMT was used from the 19th century. The word "coordinated"
> was not used, but at the time of Newton's absolute time, everyone
> thought it obvious that GMT was the same everywhere.
> 
> The only way to navigate across the oceans at that time (and until
> recently) was by celestial navigation. That is, by measuring the angular
> height of a celestial body, usually the sun, with a sextant, and
> via tables (made by the British Admiralty) and the time determine
> the position. And the time in the tables is GMT. So the navigator
> had to have a clock synchronous with GMT. Since the sun moves
> 1 minute of arc in 15 seconds, an error of 15 seconds from GMT
> will give an error of 1 minute of arc on the Earth, which is one 
> nautical mile. If the clock was 1 minute off GMT, the error would
> be 4 nautical miles, which would be acceptable in most cases.
> 
> To be in the middle of the Pacific at the 19th century and have
> a clock synchronous with GMT within few minutes was no simple task,
> but that's another (and long) story.
> 
> The point is:
> Universal time and synchronous clocks have been used for centuries!
> 
> And you claim that clock's in Oslo and Paris can't be synchronous!
> In 2024!

Well, your idiot guru has invented this
absurd in 1905, quite a long time ago,
but idiots like you are making it
lasting.


>