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From: "Paul B. Andersen" <relativity@paulba.no>
Newsgroups: sci.physics.relativity
Subject: Re: [SR] Dismaying intellectual desert?
Date: Fri, 5 Apr 2024 19:39:31 +0200
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Den 04.04.2024 02:08, skrev Richard Hachel:
> Le 03/04/2024 à 23:12, Maciej Wozniak a écrit :
>> W dniu 03.04.2024 o 22:26, Paul B. Andersen pisze:
>>
>>> Yes, we know that no speed of massive objects or particles
>>> can exceed c. So what?

The following seems to be a response to my statement above.

> 
> The notion of simultaneity being defined by the coincident existence of 
> all events occurring
> at the same time ; or again, being characterized by the set of all 
> physical phenomena
> taking place at the same time; we should be able, at least considering 
> all the components
> fixed being in a given inertial system, to speak of absolute 
> simultaneity, of synchronization
> cosmic, or common calendar -- these terms then being likely to acquire 
> real significance
> physical tion -- if we could, without it varying, transpose the 
> universal simultaneity specific to a
> particular observer to all the other inertial observers present in this 
> same frame of reference.
>     It would be enough to find any signal, or any action, by which a 
> body A could
> interact instantly with a body B, that is to say by means of information 
> propagating infinitely
> quickly, so that this notion of absolute simultaneity can be 
> experimentally proven.
>     We could then say that the action induced by body A was instantly 
> transmitted to body B, or
> that the action produced by body A was carried out at the same time as 
> its detection by body B, and that it
> exists, de facto, between A and B, a sort of reciprocal and absolute 
> simultaneity.
>      We could also imagine a round trip signal carried out over the 
> distance separating A from B, and carried out at
> means of infinitely rapid information, such that the departure and 
> return times of
> information is simultaneous. It would easily come to mind that if the 
> two watches A and B are
> well tuned, the notion of general coexistence of the things of the 
> universe in perfect simultaneity would be
> thus demonstrated.
>      However, this proof does not exist.
What's your point with using so many words to state
the bleeding obvious?

Of course there is no such thing as "absolute simultaneity".

>      We know that a body can act on another body at a distance, for 
> example in the form of a wave.
> electromagnetic, in the form of a mechanical shock transmitted along a 
> rigid rod, or under the
> form of a gravitational interaction, but we have never found a signal 
> that is infinitely fast,
> or remote action that is instantaneous. It rather seems, in fact, that 
> there exists, in nature, a kind
> impassable speed limit, which we will find in any Galilean reference 
> frame considered, and which will
> extend to all particles and all properties of physics.

So you confirm my statement quoted above above.

But you never addressed what you claimed was impossible
in my posting.

Try again?

03.04.2024 Paul.B.Andersen wrote:
> Den 02.04.2024 15:25, skrev Richard Hachel:
>> Le 02/04/2024 à 14:48, "Paul B. Andersen" a écrit :
>>>
>>> Let's stay in the real world.
>>>
>>> The only objects moving at "relativistic speeds" we
>>> can visually observe, are astronomical objects, like
>>> the matter in the jets from some galaxies (from their
>>> central black hole).
>>>
>>> The only motion we can visually observe, is transverse motion.
>>>
>>> So if the jet is coming right at us, we will see the matter
>>> at exactly the same point at the centre of the galaxy, the apparent speed of the matter is zero.
>>>
>>> But when it is approaching you at an angle, you can measure the
>>> angular velocity, and when the distance is known, you can calculate
>>> the apparent transverse velocity, which indeed may be higher than c.
>>
>> No. It's impossible.
> 
> There are _many_ "superluminal" jets where the matter in
> the jet appear to have a speed faster than c.
>
Please explain why you wrote:  "No. It's impossible."


-- 
Paul

https://paulba.no/