Georgina,

While I as a German did prefer scrutinizing the original 1905 Elektrodynamik paper, you gave a good hint to an excellent translation where e.g. I. Kinematic Part, §1. Definition of simultaneity begins (within number [8] on the right side of page) with introduction of coordinate systems, at first such a system at rest. Then the notion time is meant as what the clock usually reads simultaneous with a particular event. Einstein then questions the ubiquity of time, your unitemporal Now, Georgina.

Perhaps, he was influenced by Poincaré's "local time". In [10] he is accordingly using A_time and B_time as well as a desired time common to A and B as coordinates. In the following definition time means something quite different, the timeSPAN "needed for the light to travel from A to B" or vice versa.

To be continued

EB

A first continuation with Van Flandern's objection: Lorentz/Poincaré/Einstein synchronization (for the history see https://en.wikipedia.org/wiki/Lorentz_ether_theory#Local_time) must be considered a de-synchronization rather than synchronization. Indeed, as long as we restrict to two "material points" A and B without a relative to each other velocity v, corresponding to Einstein's coordinate system at rest, there is no reason for synchronizing A and B by means of light. In a thought experiment, we may move clock A as slowly as desired, i.e. with v-->0, to B.

Einstein gave the following condition of synchronism t_B - t_A = t'_A - t_B which means that the time of flight is the same for AB as for BA. In what Einstein called the stationary case, his equation in [10] is still "free of contradictions" even "for arbitrarily many points" (in Einstein's stationary case):

2AB / (t'_A - t_A) = t

However it is obviously not generally valid, not with v =|= 0. In order to decide to what extent Lorentz, Poincare, and Einstein just speculated, we may notice Einstein's wording:

"we assume that", "we postulate" and "with the help of some physical (thought) experiments we have laid down ... and obviously obtained thereby a definition of synchronism and time".

Einstein gave no references and didn't perform experiments.

EB

Eckard, do you think the synchronization method would not be valid for a moving system in which all of the clocks have the same velocity and so are stationary relative to each other? Apart from the stationary system that you are happy with, the moving system as I have described seems oi me the only other scenario that needs thinking about. Einstein is not suggesting that the synchronization method be used under any circumstance. Using light signals is an alternative to slow transport of clocks, being a more practical method.

Georgina,

Such "synchronization method" deliberately contradicts to your omnipresent now. Of course, Einstein claimed dealing with "moving bodies". In Lorentz's theory of relativity, this (de-) synchronization was already strange but still logically consistent together with the assumption of an aether, time dilution, and length contraction. And yes, using reflected light is a more practical alternative to slow transport of clocks - on condition, the forward path is exactly as long as is the return path - which is not the case for two moving relative to each other points A and B.

Incidentally, I dislike obscuring simple relations. The inconsistency or in other words the categorization error of Einstein's "theory" is already obvious if we omit notions like coordinate- system and rest. Let's restrict to moving relative to each other points A and B each of which may easily be understood as representing a rigid body.

EB

Eckard, the synchronization of clocks does not contradict a uni-temporal Now, pertaining to material existence. The clock display setting that is seen is part of the space-time generated by the observer and not the material reality external to the observer. There is a lack of differentiation of the seen and the materially existing in Einstein's paper. He is considering moving bodies but also observers'perception of moving bodies from the processing of received signals (although not recognized as such in the paper). Just considering material bodies and not what an observer sees isn't an improvement. What is needed is keeping in mind what category is being considered. There is a saying in English, 'don't throw the baby out with the bathwater'.

Georgina,

In contrast to SRT, Doppler shift plausibly describes all the apparent effects concerning moving bodies on the basis of the good old notions of time and synchronism which were unnecessarily questioned by Einstein.

Let me reiterate: Application of Einstein synchronization on the relation between moving bodies does not provide a reasonable picture of material reality. Einstein's general length contraction differs qualitatively and quantitatively from Doppler's apparent decrease or increase of length depending on the sign of v. Yes, length contraction, time dilution, and Einstein synchronization may be seen as due to confusion between perception and reality. However they cannot be made correct and applicable just by reinterpretation.

EB

Eckard yes it "does not provide a reasonable picture of material reality" EB., and the confusion and the paradoxes arise from thinking that the picture is the material reality and not a product that is categorically different. I think realizing that what is obtained from observation differs for different 'ways of looking' is a significant achievement of Relativity, even though it has been misunderstood. The seen 'time' related to signals from clock display settings is mutable because it isn't the display itself and is not independent of the process of observation. same for seen lengths, they are not the length of the object independent of the observation process but what is generated from the input.

Georgina,

Meanwhile, you and all others careful and honest readers of the original paper of the original paper should agree on that the use of Einstein (de)synchronization in case of mutually moving bodies is on one hand the basis of ST of Relativity and on the other hand without logical justification but contradicting common sense. Why is STR nonetheless so firmly established? Prominent scientists rejected Einstein's SRT.

Length contraction and time dilution were never observed. Perhaps a decisive argument for Lorentz gamma was and still is the so called relativistic mass increase of accelerated particles. Do we actually need SRT for explaining this well confirmed Effect? Klingman means no. Kinetic energy depends of v squared.

Mathematically formulated support for STR claims that there must be invariance under transformation. Concerning this matter, Phipps Jr. revealed that simply using partial instead total derivatives in Maxwell's equations makes a big difference. Skepticism against the almost incomprehensible general theory of Relativity absorbed for a while almost all basic criticism.

Do not forget the role of propaganda against Jews. Einstein is still admired as a genius as also was and is the catholically educated Georg Cantor who shocked everybody with transfinite numbers.

Speculations in quantum physics were prepared by the readiness to swallow other non-intuitive theories.

Incidentally, In German we used speaking of Doppler EFFECT because it is primarily a physical effect behind perception. Length contraction and time dilution cannot be observed because they are not genuine physical effects.

EB

Light clock thought experiment: what is happening in the material light clock is unaffected by what observers see. The physics happening in the same material source object clock is always the same. Light is a periodic phenomenon. Period is invariant under translation. There are however numerous factors that can affect timekeeping of real as opposed to ideal clocks. A stationary observer of a moving light clock 'sees' a diagonal rather than just vertical light path. That is an observation product generated from received EM radiation. Each seen tick appears more spread out over space-time. The spread out tick is not foundational time or change in clock display setting of a material clock (passage of clock time) but a seen image manifestation of change in clock display setting (clock time) within the observer's observation product.