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From: Python <python@invalid.org>
Newsgroups: sci.physics.relativity
Subject: Re: [SR and synchronization] Cognitive Dissonances and Mental
 Blockage
Date: Tue, 20 Aug 2024 08:16:15 +0200
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Le 20/08/2024 à 08:02, Thomas Heger a écrit :
> Am Montag000019, 19.08.2024 um 14:56 schrieb Python:
>> Le 19/08/2024 à 08:44, Thomas Heger a écrit :
>>> Am Sonntag000018, 18.08.2024 um 12:05 schrieb Python:
>>>
>>>>>> Two identical clocks, A and B, are stationary relative to each 
>>>>>> other at a certain distance. Their identical functioning (within 
>>>>>> measurement accuracy) allows us to assume that they "tick at the 
>>>>>> same rate." NOTHING more is assumed, especially regarding the time 
>>>>>> they display; the purpose is PRECISELY to adjust one of these 
>>>>>> clocks by applying a correction after a calculation involving the 
>>>>>> values indicated on these clocks during specific events, events 
>>>>>> that occur AT THE LOCATION OF EACH CLOCK.
>>>>>>
>>>>>> Einstein’s procedure is not strictly a synchronization procedure 
>>>>>> but a method to VERIFY their synchronization. This is the main 
>>>>>> difference from Poincaré’s approach. However, it can be proven 
>>>>>> that Poincaré’s method leads to clocks synchronized in Einstein’s 
>>>>>> sense. You can also transform Einstein’s verification method into 
>>>>>> a synchronization procedure because it allows calculating the 
>>>>>> correction to apply to clock A.
>>>>>>
>>>>>> *Steps of Einstein's Method:*
>>>>>>
>>>>>> When clock A shows t_A, a light signal is emitted from A towards B.
>>>>>>
>>>>>> When this signal is received at B, clock B shows t_B, and a light 
>>>>>> signal is sent from B back towards A.
>>>>>>
>>>>>> When the signal is received at A, clock A shows t'_A.
>>>>>
>>>
>>>>> Relativity requires mutally symmetric methods. So if you 
>>>>> synchronize clock B with clock A, this must come to the same 
>>>>> result, as if you would synchronize clock A with clock B.
>>>>
>>>> It is.
>>>
>>> No, it is not!
>>
>> It is. It is explained in my initial post : What is (AB)/c to you?
> 
> AB was actually meant as:
> 
> distance from A to B,
> 
> even if A and B are in fact position vectors, hence AB would usually be 
> the scalar product of A and B (what is absurd).

Yes it would be absurd. BTW you are conflating affine spaces with
vector spaces here.

> Besides of this little formal issue (actually meant was |r_AB| ), 

Well, Thomas, this is utterly ridiculous. Any reader understands what
AB as it appears in 2AB/(t'_A - t_A) is the distance AB. From high
school to Ph. D.

> Einstein had not written AB/c (or r_AB/c).

It appears after ONE step of elementary algebra from the two first
equations on page 3 there :

https://users.physics.ox.ac.uk/~rtaylor/teaching/specrel.pdf

Do you really think that readers (physicists) in 1905 couldn't
immediately recognize this from two so simple equations, Thomas ?
Really ?

> What he had actually written was
> 
> r_AB/(c-v)

This is in paragraph 3. We are dealing with paragraph 2 here.

>>> Einstein's method did not allow mutally symmetric synchronization.
>>
>> The procedure can be proven symmetric. Face it.
> 
> No, it wouldn't.

It can be shown. This is a very simple exercise even for high school
students. You cannot seriously pretend to be an engineer Thomas.

> I take as example two spaceships in 1 lightseconds distance, which are 
> called A and B.
> 
> 
> 
> Both have a HUGE clock strapped to that spaceship and use a VERY HUGE 
> telescope to read the clock of the other ship.

The is NO reading of another clock with a telescope in the procedure
described at paragraph 2 (nor elsewhere in the article)

There is no point in addressing something you made up and is by
NO WAY related to something Einstein wrote or implied.

> Now clock A shows 12 o'clock and zero seconds.
> 
> Ship B reads this at time 12 o'clock plus 1 second, but turns the own 
> clock (showing 12 o'clock plus one seconds) back by one second.
> 
> Now the observer of ship A reads the clock from ship B and reads 12 
> o'clock plus zero seconds, while the own clock shows 12 o'clock plus one 
> seconds.
> 
> This is regarded as an error and the own clocks as being ahead, hence it 
> was turned back to 12 o'clock plus zero seconds.
> 
> This is seen from ship B, where the own clock shows actually 12 o'clock 
> plus one second. This is corrected by adjustment of one second, by which 
> that clock is turned backwards.
> 
> This could go on forever, while both clocks would stand still.
> 
> But certainly this is not what you would call 'synchronization'.

Sure. Hopefully this is not at all related what Einstein wrote. This
is, again, something you MADE UP out of nowhere. You are actually
describing Hachel's defective, inconsistent, "method", not Einstein's
one.

I know your French is bad, nevertheless everything I wrote in my
initial post has been recomposed in LaTeX, the pdf is there :

https://gitlab.com/python_431/cranks-and-physics/-/blob/main/Hachel/dissonance_lengrand.pdf

(there were ONE mistake in ONE equation in my initial post, could
you find it?)

Alternatively you can read Paul's post in this thread, he's explaining
Einstein's method of synchronization too. He is synchronizing B on A,
while I'm synchronizing A on B. Nevertheless it leads to the same
result : Einstein's method is consistent AND symmetric.