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From: "Paul.B.Andersen" <relativity@paulba.no>
Newsgroups: sci.physics.relativity
Subject: Re: Sync two clocks
Date: Fri, 23 Aug 2024 13:23:59 +0200
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Den 22.08.2024 21:12, skrev Richard Hachel:
> Le 22/08/2024 à 20:19, "Paul.B.Andersen" a écrit :
>>  
>> It is no absolute and universal simultaneity.
>> 
>> Since you still seem to think that it was Richard Hachel
>> who  discovered this, it is obvious that you do not read
>> what I and others write to you.
>> 
>> Den 22.08.2024 Paul B. Andersen wrote:
>> |
>> | And you believe it is YOU that have discovered that? 😂
>> |
>> | Before 1905 everybody believed it was a "universal, present now",
>> | that simultaneity was absolute, and that clocks could be
>> | absolutely synchronised. Newton took it for granted!
>> |
>> | But Einstein showed that there is no absolute simultaneity,
>> | and clocks can't be absolutely synchronised.
>> |
>> | https://paulba.no/paper/Electrodynamics.pdf
>> | See: § 1. Definition of Simultaneity
>> |
>> | Did you really not know that it was Einstein who discovered this? 😂
>> 

> 
> Let's admit it, Paul.
> You're wrong, Einstein didn't say anything at all, and always just 
> repeated what Poincaré said, but hey, it doesn't matter, we'll admit 
> that you're right.

https://paulba.no/paper/Electrodynamics.pdf
Quote from § 1. Definition of Simultaneity:
-------------------------------------------
"If at the point A of space there is a clock, an observer at
  A can determine the time values of events in the immediate
  proximity of A by finding the positions of the hands which
  are simultaneous with these events.
  If there is at the point B of space another clock in all
  respects resembling the one at A, it is possible for an observer
  at B to determine the time values of events in the immediate
  neighbourhood of B.
  But it is not possible without further assumption to compare,
  in respect of time, an event at A with an event at B.
  We have so far defined only an “A time” and a “B time.”
  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.
"

If you can read, you will see that Einstein did say what I said.


> There's just one thing I don't understand in your grievances and mockery.
> What do you mean by: "I, Paul B. Andersen, think that there is no 
> absolute simultaneity, and that not all watches can be synchronized"?

I meant what I wrote and you snipped:

>> There is no _absolute_ simultaneity, but Einstein _defined_
>> what he meant by simultaneity _in an inertial frame_.
>> And with this _definition_, we can make two clocks at different
>> locations in the inertial frame simultaneously show the same;
>> the clocks are synchronous _in said frame of reference_.
>> But they are NOT synchronous in a frame of reference which
>> is moving relative to the first frame of reference.

This is what is said in § 1. Definition of Simultaneity.

> Python said that the terms had to be clear (for once, he's not lying).
> The terms have to be clear.
> In the introduction to my pdf, I wrote two A4 pages (in a compressed 
> handwriting) and without putting a single equation, just to talk about 
> the notion of simultaneity, proof that it's not so obvious (even if it 
> makes you laugh).
> I too am talking about the notion of simultaneity, but am I sure we are 
> talking about the same thing?
> Is Einstein talking about the same thing?

I am quite certain that Einstein wasn't talking about
the same thing as Richard Hachel.

> Can you explain to me, in the greatest clarity, as Python recommends, 
> what you mean, what you understand by the following words: "In special 
> relativity, the notion of simultaneity is relative"?

https://paulba.no/paper/Electrodynamics.pdf
Read:
§ 1. Definition of Simultaneity
§ 2. On the Relativity of Lengths and Times

It is explained with the greatest clarity.

> This is very important, and it is the very basis of the theory as it 
> actually exists in nature.
> What do you mean by these words?

It is remarkable that a person who pride himself of having studied 
relativity issues for 40 years is ignorant of the most basic concepts
in the Special Theory of Relativity.

I am not going to teach you SR (or GR).
If you really want to learn, read a book.

> Do you mean that the internal chronotropy of watches is relative?
> Do you mean that the notion of instant is relative to position (spatial 
> anisochrony)?
> Do you mean something else?

I mean that you are babbling nonsense.

> Personally, I define my words, and I explain what I consider clearly.

:-D

> I would be very happy to understand you and for you to be able to define 
> your words.

All the "words" used in SR are defined in any book about relativity,
but you have to read it yourself.

I will remind you:

In the world there are millions of clocks which are synchronous
in the ECI frame, and the world would be even more chaotic than
it is without them. Think if it was no way to tell you when your
train or aeroplane would go, and there was no way to tell you
when you would arrive at the destination.
The world is _very_ dependent on synchronous clocks.
The civilisation as we know it couldn't exist without them.

And you say it is impossible to synchronise clocks? :-D

-- 
Paul

https://paulba.no/