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From: "Paul.B.Andersen" <relativity@paulba.no>
Newsgroups: sci.physics.relativity
Subject: Re: The problem of relativistic synchronisation
Date: Sat, 31 Aug 2024 22:11:51 +0200
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Den 31.08.2024 09:05, skrev Richard Hachel:
> It would not occur to anyone to place two solar clocks in their garden. 
> If it is well oriented, the time displayed is the right one.
> No need for two solar clocks.
> 
> On the other hand, if I am no longer in Berlin, but in Nantes, I cannot 
> be satisfied with taking continual selfies of my Berlin solar clock to 
> have the solar time at Nantes. Everyone understands the ridiculousness 
> of the situation (except Python and Paul.B Andersen). If I am in Nantes, 
> I have to look at the time on a clock in a Nantes garden, and I cannot 
> say to my wife: "What time is it now? Please send me a selfie of my clock."

If you are in Nantes and want to go to Berlin by train,
and you see in the timetable that your train will leave Nantes
at the time 8:32, which clock would you use to be at the railway station 
at the right time, the solar clock in Nantes, or your wristwatch
which is showing UTC+2h?

Your wife, who is in Berlin see in the timetable that the train
will arrive in Berlin at the time 20:41. Which clock would she
use to meet you  at the railway station at the right time,
a solar clock in Berlin, or her wristwatch which is showing UTC+2h?

When the train leaves Nantes, you see the clock on the railway station
showing 8:32, and you start your stop watch. When you arrive Berlin,
you see the watch on the railway station showing 20:41. You stop your
stop watch which show that the duration of the journey is 12h 9m.

How is it possible that the difference between the Berlin clock
at arrival and the Nantes clock at departure is equal to the duration
of your journey, 20:41 - 8:32 = 12h 9m ?

Could it be that the clock at the railway station in Berlin
and the clock at the railway station in Nantes are synchronous?

You will of course not respond to this.

You will flee, as you always do.

Won't you? :-D


> We cannot, even by slapping them in the nose, or kicking them in the 
> balls, synchronize solar clocks with each other. They will NEVER mark 
> noon at the same time in Berlin, and in Nantes.

Why are you stating the bleeding obvious?
Solar clocks can't be synchronised.

That's why we use clocks showing UTC+2h in Nantes and Berlin.
They do mark the time 12:00 (which is not the noon) at the same
time in Nantes and Berlin.

Same time = simultaneously as defined by Einstein.

> 
> Paul B Andersen has just informed us that a watch slowly transferred to 
> the moon shows the same time as a watch left on my desk

Le 24/08/2024 à 21:12, "Paul.B.Andersen" a écrit :
| If we use three weeks on the transfer, and we ignore the gravitational
| blue shift, and pretend that the ECI frame is a true inertial frame,
| then the lunar clock will lag 0.45 μs on the Earth clock.

So the clocks are not synchronous to within ns,
but they are synchronous within 1 μs which will be acceptable
in most cases.

In your example 1 second was the resolution of the timing.
And you agreed that the clock at your table and the lunar clock
would be synchronous.

| Den 26.08.2024 13:02, skrev Richard Hachel>
|> There is a one-second time difference between 00:00:08 and 00:00:07",
|> between my watch and the watch on the moon.
|> This is because of the speed of light, which is quite slow,
|> and takes at least a second to reach me.

so when you see in the telescope the lunar watch showing 00:00:07",
the lunar watch will simultaneously show 00:00:08, the same
as the watch  at your table.

> He does not understand that there is a real procedure of natural 
> desynchronization by spatial position,

If the clocks are moved relative to each other in an asymmetric way,
they will not stay synchronous.
In this case the clocks are 0.45 μs out of sync.

> just as there is also a real 
> procedure of reciprocal dyschrnotopia when we make watches evolve 
> between them at relativistic speeds (they do not even beat at the same 
> rhythm anymore, and conversely, each beats faster than the other).

An awkward way of explaining mutual time dilation.

https://paulba.no/pdf/Mutual_time_dilation.pdf

> What should we do to make him understand?

As shown above, I understand everything.

-- 
Paul

https://paulba.no/