1 A rigid rod with 8 clocks, preface

Consider two rods, with each 8 clocks, moving along the x-axis. Observations reveal that the distance between the two rods changes.
1) The first question is: can both rods be at rest? The answer is: one can be considered at rest but not both.

When that is the case something must have happened in the past to create this situation.

That is why we start from the situation that both rods are at rest and give one rod a power boost to get it moving. We now have two rods: rod 1: at rest, and rod 2: moving.

2) The next question to ask is: Is it possible by means of an experiment to decide if a rod is at rest or moving.

To answer that question I will try to describe a certain number of experiments as detailed as possible.

The first thing we perform is clock synchronization for all the clocks of both rod 1 and rod 2.
(Clock synchronisation is discussed in the posting: A rigid rod with 8 clocks) Next, you give all the engines of rod 2 a boost. Thereafter When a clock at rest meets a moving clock they can be compared. The results show that the moving clock runs slower than a clock at rest. You can repeat the same experiment in the opposite direction and the result is the same: the moving clock runs slower than a clock at rest.

This is an important result because it means that the behaviour of a moving clock is symmetric in both directions, starting from a state at rest.

3) The next question to answer is this also true when we start with a moving rod?
The first thing we do is to make two copies of rod 2 and we call them rod 3 and rod 4. The second thing we do on both rods we perform a clock synchronization. Thereafter we give the engines part of rod 4, a boost in the same direction as original for rod 2.

4) You cannot compare the clock rate of rod 2 with rod 3 because their speed is the same.
However, you can compare both rod 2 and rod 3 with rod 1 when they meet because their speed is different. The results are: that all the readings of rod 1 are the same, all the readings of rod 2 are the same but lower and all the readings of rod 3 are different.
In fact, if you assume that both rod 2 and rod 3 move towards the right than the reading of clock #1 (towards the left) is the lowest and the reading of clock #8 (towards the right) is the highest. This is in agreement with the physical idea that clock #1 is reset first and clock #8 the latest.
This is a very important physical implication. The moving clocks part of rod 3 and 4 don't run individual simultaneous (compared with rod 1 and rod 2)

5) This has also a physical consequence when we give the engines, part of rod 4 a boost, immediate after the received reset signal or based on a certain clock reading: the engines will not fire simultaneously.
The has physical consequences because this unequal firing will cause internal forces, which in this case will try to decrease the length of the rod.

The consequence is that in fact, you should not use a rigid rod.

6) Consider rod 2. This is the same situation as discussed in item (2) above. When the engines are fired for the first time. the rod will move in a certain direction and the moving clocks will run slower as the clocks at rest. Fire the engines again and the clocks will run slower again.
This is called: the decision situation or moment. At this specific moment, you can do two things.
You can fire the engines again and the clocks will run even slower. Or you can first reverse the direction and then fire the engines. In that case, the clocks will start to run faster.
This behaviour is called asymmetric.

2 A rigid rod with 8 clocks, preface

Yes, this is an answer; another answer is: of course they both can be considered. We can also answer that it depends on ... [a lot of possibilities here].
Applying common sense the limits are fuzzy. Rejecting common sense there is no limits.

3 A rigid rod with 8 clocks, preface

>	Consider two rods, with each 8 clocks, moving along the x-axis. Observations reveal that the distance between the two rods changes. 1) The first question is: can both rods be at rest? The answer is: one can be considered at rest but not both.

You can't, state that, unless a third part Observer. Try again.

4 A rigid rod with 8 clocks, preface

How are rigid rods free to contract? No. Contracted atoms lead to chemistry gone awry.

Mitchell Raemsch