Re: The problem of relativistic synchronisation

Am Freitag000006, 06.09.2024 um 13:31 schrieb Richard Hachel:

Le 06/09/2024 à 12:31, Thomas Heger a écrit :

Usually we have an observer (say 'A') at a certain spot (also called 'A'), who measures distances from his own position.
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The measured object (say 'B') moves - say- away at a certain speed v.
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But seen from B the point A moves away with the same speed, though into the opposite direction.

  Here, already, there arises a problem that physicists do not see, or even deny for forty years, that is to say since I told them.
How is this speed characterized in a relativistic universe?
There are three ways to propose what A sees of B.
-The real speed (which is a primordial concept but is never used, except in a roundabout way by posing m'=m/sqrt(1-v²/c²), which is an absurdity imposing the relativity of masses. A bus becoming two buses by change of reference frame.
-The observable speed, measured with two separate watches A and B, and which is the classic speed used, but false.
- The apparent speed (what we see with the naked eye in telescopes because of anisochrony, that is to say the inverse of the speed of light).
 We therefore have three simple notations of what a speed is.
 Vr, Vo, Vapp.
 We will note that the absence of a preferred reference frame in the universe,
means that these three speeds remain constant by permutation of observer.
 Let us pose an entity B which moves away from A at 0.8c (speed in classical notation). We have Vo=0.8c, Vr=(4/3)c, Vapp=(4/9)c.

We are talking here in the context of SRT.
But SRT assumes inertial frames of refence, hence assumes a background space, which is not the real universe we live in.
In SRT there exist only unaccelearted streight worldlines, along which any object would float.
This is not how the real universe operates, where practically nothing moves in a streight line.
Now we can only use the SRT background here, because otherwise SRT would not work, anhow.
This SRT-space would allow to regard any movement along a streight line as being equivalent to an object at rest.
Now we could repeat the same trick and apply 0.8 c once, stop that to zero, apply 0.8c a second time and still are allowed to halt this to zero.
But how would you introduce a 'speedlimit' in a space with such features?
TH