Horizontal coordinate of red particle
Horizontal coordinate of blue particle
Step's length of red particle in pixels
Step's length of blue particle in pixels
Speed of the system compared to c
Roundtrip time of the photon
. . .
This simulation shows two bonded particles moving by offset steps to the right or to the left while the information about their location takes time to reach them. For extra-slow motion, hold the "Enter" key down after having hit the "One Step" button. You must also stop the acceleration before reversing it. To know how the program works, right click on the screen and select "Source code". I took care to describe each code line so that anybody can easily follow the logic.
Contrary to the original simulation on acceleration in opposite directions, this time, the two particles travel the same distance during the time the photon makes a roundtrip, so there is no constant contraction, just a temporary one due to the accelerated particle making its step before the other one steps away. Again, the accelerated particle waits till the other one has accelerated away from it before accelerating its step another time. When acceleration reverses though, the system is already making constant steps, and the particle that is not on the deceleration side can't avoid to make a step towards the one that it is actually decelerating because it doesn't yet know about that deceleration, so it has to undo this last step when the photon strikes it. To better understand why, imagine that we hold the blue particle at rest on the screen while still accelerating the red one: the photon sent by the red one would then simply be reflected by the blue one, and it would simply move the red one backward later on. This way, the decelerated particle also waits until the other one has decelerated away from it before decelerating another time. It is worth noting that this feature is not a simulation trick, it is exactly how the particles would have to behave if the information they exchange to keep their bonding energy constant was not instantaneous.
That mechanism seems to produce some kind of length contraction at the scale of the particles, but not at our scale. In a solid for instance, the steps would first propagate from atom to atom in a wave manner, and at the end of the process, half the atoms would be making a step while the other half would be waiting to make his, what would produce no length contraction. Contrary to relativity, it would still produce time contraction though: the longer the steps, the less the photon takes time to do its roundtrip. At steps' half way between the particles for instance, the speed of the system gets to .5c and the time the photon takes to make its troundtrip contracts to .75 . Now, what about the MM experiment? Would my simulation with four particles still show a null result? It should since the principle behind that kind of small steps is still synchronisation, but to be sure, I will begin by using it in a simulation with four particles.