Path: ...!feeds.phibee-telecom.net!2.eu.feeder.erje.net!feeder.erje.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Python <python@invalid.org>
Newsgroups: sci.physics.relativity
Subject: Re: The problem of relativistic synchronisation
Date: Fri, 30 Aug 2024 15:43:05 +0200
Organization: CCCP
Lines: 140
Message-ID: <vasi99$e2la$14@dont-email.me>
References: <m_uze6jFLkrMPuR4XaNmQntFPLY@jntp> <va9tpv$te1n$1@dont-email.me>
 <uFAyL-g_jsWF5wwLXINmyrzxquo@jntp> <vaa4om$sicr$16@dont-email.me>
 <tAXYNx1-wzYUg_H0N6FWnLiQgFs@jntp> <vasgsq$go2j$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Injection-Date: Fri, 30 Aug 2024 15:43:06 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="f01e2221d99b21c0754b16fe041d7c3a";
	logging-data="461482"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX18J64hgNQ1bKVtD9wo+xZAn"
User-Agent: Mozilla Thunderbird
Cancel-Lock: sha1:q7NNaDNa4Gbk9ct1aw4Ljky3zFE=
Content-Language: en-US
In-Reply-To: <vasgsq$go2j$1@dont-email.me>
Bytes: 6519

Le 30/08/2024 à 15:20, Paul.B.Andersen a écrit :
> Den 30.08.2024 00:15, skrev Richard Hachel:
> 
> Let's analyse Richard's post.
>>
>> Speaking of that, personally, I give up a little, even if I am 
>> convinced of the usefulness of a short article of a few lines on the 
>> notion of simultaneity
>> and synchronization (the basis of RR).
>> I think that on average (too bad if it hurts them) the regulars are 
>> too stupid, I especially mean too stupid aside from the dick, the 
>> dick, always the dick.
>> It's very unfortunate, but we don't come out any more here on the 
>> Anglo-Saxon forums than on the French-speaking forums. It will be 
>> about who is the stupidest with the biggest dick.
> 
> I have never seen anybody but Richard Hachel boast of his big dick,
> so who are the "regulars" he is accusing of doing so?
> 
>>
>> It's a shame, there is nevertheless food for thought, and certain 
>> reflections are sometimes interesting,
>> like the posts on relativistic synchronization between two points A 
>> and B.
> 
> So Richard is talking about Einstein's synchronisations method.
> 
>>
>> It sometimes goes well (like your explanations of events e1, e2, e3) 
>> and the fact that we can already
>> offer CAREFUL evidence before going any further.
> 
> "You" is probably Python. Richard never quote what he is
> referring to, and he doesn't define the events e1, e2, e3.
> But we know:
> e1 is the event that light is emitted from A
> e2 is the event that light is reflected from B
> e3 is the event that the reflected light hits A
> 
> Note e1 and e3 are happening at A, e2 is happening at B.
> 
>>
>> We can then pose without fear: tA(e3)-tA(e1)=2AB/c
> 
> tA(e3) is the reading of a clock at A at the event e3
> tA(e1) is the reading of a clock at A at the event e1
> 
> Einstein says:
> "We assume the quantity 2AB/(tA(e3)-tA(e1)) = c
>   to be a universal constant—the velocity of light in empty space."
> 
> It is a postulate in SR that say the speed of light
> in vacuum is constant and invariant, and his paper is about
> the consequence of the postulates, so of course he assumes that.
> 
> It is thoroughly experimentally verified that the speed
> of light indeed is constant and invariant.
> So we _know_ that tA(e3)-tA(e1)= 2AB/c
> 
>> Then, admitting that A warns of e1 and e3, either with photons or with 
>> slugs of the same speed, any point M of the stationary frame of 
>> reference, we have yet another tautology:
> 
> This statement doesn't parse.
> 
>>
>> tM(e3)-tM(e1)= tA(e3)-tA(e1) = 2AB/c
> 
> tM can only be the reading of a clock at the point M,
> which is an arbitrary stationary point in the frame where
> A and B are stationary.
> 
> But the events e1 and e3 happen at A, and not on M,
> so tM(e3)-tM(e1) is meaningless.
> 
> Richard doesn't seem to know what an event is.
> 
>> For the moment we cannot say more about the speed of light between A 
>> and B in the direction AB,
>> nor in the BA sense.
> 
> Above Richard say the posts on relativistic synchronization
> between two points A and B are interesting, but so far he
> has said nothing about synchronization.
> 
> The equation:
>    tB(e2) - tA(e1) = tA(e3) - tB(e2)
> is Einstein's _definition_ of synchronism and simultaneity.
> If this equation is true, then the clocks are synchronous
> in the frame where A and B are stationary.
> 
>>
>> On this, we breathe we breathe, Einstein does not seem to agree with 
>> Hachel. For Einstein, the question does not arise, and it seems 
>> certain that t(AB)=t(BA).
> 
> What are you saying? :-D
> 
> Einstein says:
> "We have not defined a common “time” for A and B, for the latter
>   cannot be defined at all unless we establish _by definition_
>   that the “time” required by light to travel from A to B equals
>   the “time” it requires to travel from B to A."
> 
> And:
>   "In accordance with definition the two clocks synchronize if
>       tB(e2) - tA(e1) = tA(e3) - tB(e2)"
> 
>   tB(e2) - tA(e1) is the time the light uses to go from A to B
>   tA(e3) - tB(e2) is the time the light uses to go from B to A
> 
> Einstein _defines_ that the clocks simultaneously show
> the same (are synchronous in the stationary system)
> if the time the light uses to go from A to B equals
> the time the light uses to go from B to A.
> 
>>
>> Except that this is no longer true in an anisochronous environment, 
>> and that our universe is not "a 4D hyperplane of absolute 
>> simultaneity, even for a simple inertial frame of reference".
>> We can then propose A synchronization based on A hyperplane of 
>> simultaneity, but we must propose THE appropriate candidate, and it 
>> can obviously be neither A nor B.
>> So we continue from there.
>> We can then propose a synchronization of A and B by M (and we will 
>> have a synchronization of type M).
> 
> SR doesn't depend on the definition of simultaneity
> (but everything would be very awkward without it)
> so another definition is possible.
> 
> But in the real world no other than Einstein's definition
> would work, so no one would use your alternative definition.

This is exactly what I tried to explain him on fr.sci.physique.

In vain.