Re: [SR and synchronization] Cognitive Dissonances and Mental Blockage

Am Dienstag000027, 27.08.2024 um 12:25 schrieb Richard Hachel:

Le 27/08/2024 à 07:31, Thomas Heger a écrit :
 

The very word 'relativity' requires mutually symmetric perspectives.

 Absolutely.
 

Since both perspectives are of equal rights, we need to accept both views as valid, hence need mutually symmetric perspectives.

 Magnifico! Wunderschön !!!
 

Thanks.
But this is obvious and certainly not disputed.
But Einstein, however, had not written about a symmetric system of clock synchronization.
Instead he used something, one could call 'external time' (kind of 'true time').
But there exists no such thing as true time and time is only local.
This would mean, that a clock at point A would shows the local 'A-time' and clocks at point B show B-time.
This would not necessarily allow to synchronize clocks at all, if A-time does not run at the same tick rate as B-time.
But supposed you have a clock from A, bring that to B and synchronize this by technical means with A-time-clocks at A.
Now: what would you need to do, to synchronize these clocks?
It needs to be a way, which could also be applyed at B and would give the same result.
Since we need some sort of operators at both sides, we need to assume, that at both locations are some kind of itelligent beings and these able to read messages and operate a clock.
These 'observers' get also names and we could them 'A' and 'B' for simplicity.
The operator A would send out a signal, which gets sent back by B, once it arrives at B.
'A' would measure the delay for the round trip, cuts that value in half and send the value to the far side B, together with a coded time message.
The observer B would decode the message and adjusts the clock in question aappropriately.
Now B could do the same and would gain the same result.
This is therefore a valid method to synchronize clocks.
The method used by Einstein is not valid, because actually ONLY 'A-time' was used and no operator at the far side was mentionend.
Another method, which is often used in textbooks about relativity requires a 'man in the middle' (called 'M', for instance).
This is a possible way to synchronize clocks, too.
But this method had the disadvantage, that synchronization would depend on the position and state of motion of the observer 'M'.
This method would also only allow to synchronize two clocks, while synchronization should be valid throughout an entire frame of reference.
TH