Re: Space-time interval (2)

Le 13/08/2024 à 19:53, "Paul.B.Andersen" a écrit :

 So you have given up gesticulating about universal anisochrony
and why that makes it impossible to have synchronous clocks
in Oslo and Paris?
 Try to explain it again?
 |> Den 22.07.2024 21:37, skrev Paul.B.Andersen:
|>>
|>> You know of course that all clocks in the same time zone
|>> are synchronous. In France and Norway clocks are currently
|>> showing UTC + 2 hour, so my clock and your clock are actually
|>> synchronous.
|>>
|>> Please explain why our clocks are NOT synchronous.
|>> (To within few seconds|
|
 |> Den 22.07.2024 23:55, Richard Hachel responded:>
|>> But I keep explaining it to you.
|>>
|>> This is a property of space that can be called universal anisochrony.
|>>
|>> This does not translate into the idea that the “plan of present time”
|>> so dear to physicists does not exist, it is a thought that seems
|>> logical to them, but it is an abstract thought.
|>>
 Let's assume that both clocks show UTC + 2h within a second.
 I leave Oslo Airport (Gardemoen Airport) when the watch on
the airport shows 12.00.00 ± 1 s
I arrive at Paris Airport (Charles De Gaulle Airport) when
the watch on the airport shows 13.30.32 ± 1 s.
The difference is T = 1h 30m 32 ± 2 s
The distance in the ground frame between the airports is
L = 1358.03 ± 0.1 km
 v = T/L = 250.01 ± 0.11 m/s = 900.0 ± 0.4 km/h
 Please explain why this is not a real speed
in the ground frame.
 Richard, will you flee yet again? :-D

No, no, I am not trying to escape. I have forty years of relativistic concepts behind me, and I have a perfect grasp of how things should be taught.
There are several keys to understanding RR, and either none of these keys are understood, or they are half understood, and that is not satisfactory.
The first key, which is absolutely necessary to open the theory, is the notion of universal anisochrony.
This made a lot of people laugh 40 years ago, because people did not understand this term, nor what I meant by it.
Today, it is a little less funny, and many ask me to explain it in a simple way, because the concept, although elementary, is not obvious to everyone.
What is universal anisochrony?
It is a property of space, just as universal gravitation is a property of bodies.
This means that the notion of absolute universal present is an abstract thought.
There is no present moment at this moment that is at the level of a planet that orbits Altair, for example, and that corresponds reciprocally to my present moment.
In short, the notion of a flat present does not exist.
It is a thought anchored in man (like the flat earth before), but which is only a human a priori.
Strangely, this simple idea, which corresponds perfectly to an intelligent physics, is abandoned by men, while they understand very well a more difficult concept which is the relativity of the internal chronotropy of watches by change of inertial reference (gamma factor).
We come back to Paris, and to Oslo.
There is therefore a natural anisochrony between Paris and Oslo.
There is no "flat present", "horizontal plane of present time" between Paris and Oslo. I repeat, it is useless, false and abstract.
So there is a natural, irreversible gap between the two. If we synchronize the watches on Paris, an event that will occur in Oslo will not exist for Paris.
An event that will occur in Paris will not exist in Oslo.
This event is only found in the "future of the other".
And so on for the entire universe.
We will always have a time interval, an anisochrony,
which will be related to the distance.
"My present is not your present, and your present is not my present, there is no absolute universal simultaneity"
So how do we make all this agree anyway?
We will create a universal time, an abstract universal present, which does not exist, and which corresponds to a synchronization made by an observer placed in a fourth spatial dimension which does not exist, but which is very useful, because mathematically,
if it is placed very far, perpendicular, and at an equal distance
from all the points of the three-dimensional metric universe which is ours, it observes all the points in a constant perfect simultaneity.
This point is abstract, does not exist, but allows us to use a universal time and a perfect present time plan.
But this perfect present time does not exist.
This does not prevent that in our universe, each point considered is, in general at a different distance from me, and that it is impossible for me to synchronize with it, without desynchronizing myself from it, and without desynchronizing myself from the others and so on.
R.H.