Anyway what does it mean that something is not absolute but relatif? What has an observer to do with this issue. Does it makes any difference to use space not absolute but relatif?
                 t2 .   . .   . .   . .   . .  t1. .t3  . .   . .   . .   . .  t0 Y   X Figure 1A v=0 
t5 .  .  .  .   .   .   .t4   . .   . .   . .t3  . .   . .   .t2 .   . .   . .  t1. .   . .   . .  t0 Y   X Figure 1B v > 0 
.   .   .   .t5   .   .   .   .   .t4   . .   . .t3  . .  . .   .t2 .   . .  t1. .   . .  t0 Y   X Figure 1C v > 0 
  Y    Yt3    .Y    . Y     . Y     . Y     t2 . Y     . . Y     . Y.t1     . Y .   . Y .  t0. Y .t0  . .   . .   . .   . .   Y   X Figure 2 v > 
The events are simulataneous assuming an observer at rest if the distance between the observer and the two markers (at rest) is the same.
In figure 2 the two bolts of lightning are the two events t0. The observer on the platform observes them simultaneous at t2. This whole effect is independent of the length of the train. As such this issue is not special for SR or GR because no Time dilation and Length contraction in this example is involved. 
Comments on the article Quantum_and_classical_clocks.htm "Einstein’s quantum clocks and Poincaré’s classical clocks in SR" by Yves Pierseaux

The problem is also when two events happen simultaneous I have to be at specific places to observe them simultaneous. To be more precisely I have to be in the plane half way between the points where the two simultaneous events happened at the moment when the light signals hit that plane (simultaneous).
Figure 3 shows two events E1 and E2. After they happend they can move away. 

Figure 4 depicts 2 frames: One in rest and one moving. The vertical axis is the time and the horizontal axis is the X axis. In each frame there are three clock marked C(c) and three light sources sources S(s) to synchronise the clocks. The small letters are used to indicate refernce frame 2. In this particular Figure the distance between the Clocks in both frames is identical. This means in the frame at rest there are simultaneous events when the clocks meet. The question is what is observed in the moving frame. In Figure 5 the distance is not the same. At each Clock there are also mirrors which are used to reflect lightsignals and to synchronise the clocks. 

But the question is: is this correct? Figure 5 shows 5 examples assuming that moving clocks tick slower. The distance AB and BC are equal.




Figure 6 shows the situation were the distance between the clocks in frame 2 is shorter than the distance in frame 1. The distance in frame 1 is 15 units and in frame 2 10 units.

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