(CONTINUED FROM PREVIOUS POST)
Now, based on everything I said in the last post, I want to answer to your point that "In Newton's mechanics time is seen as a linear flow with the same rate for observers", and your comment/question a little further down, that "In this case I was expecting something more like your notion of time. I mean, what do you understand by the word "time"? A flow, change, a substance, etc.?"
You weren't satisfied with my definition of time in terms of existence, and were looking for a word like "flow". I intentionally avoided using the word "flow" even though that's roughly what I mean by "exist" anyway. I mean that I would define time just as Newton defined absolute time, except that I'd add a note that by "flow" I DO NOT mean flow through a substantive dimension, which the definition can easily be taken to mean. Rather than flow along a substantive dimension, I suppose I'd say more properly I mean flow as an absolute dimension, so that, as with classical mechanics, I mean that at any instant the three-dimensional Universe, and only the three-dimensional Universe, constitutes all of reality.
If you understood my previous post, you'll know what I mean by this.
Now, in between the two statements I just answered to, you noted that relativity complicates such a view and asked if I have a solution to the problem. Actually, more specifically you asked, "Since the mathematical formulation is the one that matter for practical purposes. So mathematically speaking, do you have any solution?"
I have a suspicion that you've got something else entirely in mind, and therefore may not consider my answer too carefully, but I'll give it to you anyway: Actually, the statement that the mathematical formalism is all that matters for practical purposes is incorrect. In practice, in order to correctly make use of the mathematical formalism, we need to take observation into account as well--and the cosmological data clearly indicate that there is an ultimate cosmic rest-frame. I discussed this in my last essay, referenced it in the current one, and tried to explain it to you further during the previous contest. I discussed why this matters, practically, in both of my essays; but I'll briefly explain that here.
Since the predictions made through the mathematical formalism have been verified, it's reasonable to assume for now that there's nothing the matter with the math. The issue, then, becomes one of consistently reconciling the mathematical formalism with ALL the observations. And in that sense, yes, I do think I have a solution. Put far too simply to be entirely convincing to everyone, the solution is that, according to the cosmological observations, there IS an ultimate cosmic rest-frame, and an associated "true"--i.e. absolute--simultaneity-relation. Mathematically speaking, in any inertial frame BUT the cosmic frame, the hypersurfaces of absolute simultaneity won't be orthogonal to the proper time axis--i.e. they'll be tilted--BUT that doesn't mean that they won't still "flow equably along that axis" (please recall, that by flowing equably along an axis, I don't mean a substantive dimension).
I don't like using the words "privileged" or "preferred" reference frame to describe the cosmic reference frame, because these are the words of relativists who historically wanted to claim the objectivity of their stance, and argued that each observer's proper frame should be considered to be as good a reference frame through which to describe "true reality" as anyone else's, and therefore liked to claim that there's no such thing. I call bulls**t.
The point that I tried to make in my essay with the Albert and Henri example is that this is actually wrongheaded. Sure, Henri is free to frame things in such a way that the clock across the train car "remains at a fixed distance from him, and both of them remain motionless". But if he opens his eyes to the world around him, he should see that he's actually moving--i.e. he's not "truly" motionless. Then, he should realise that a photon that travels from the clock to him DOESN'T truly make it all the way across that fixed distance, because from point of emission to point of observation Henri ACTUALLY moved forward and met it part way. Mathematically speaking, this all works perfectly well according to what I said above about absolute simultaneity being tilted in Henri's frame of reference.
Now, the Machian argument against this is "How can Henri or Albert really *know* that Albert's frame is the correct one to use?" In actuality, it isn't: the Earth orbits the Sun, which orbits the Galaxy, etc. But what matters is that there IS one objective cosmic frame, which we have been able to observe to an unprecedented degree of confidence. We "know", with as great a degree of scientific knowledge that we "know" anything, that we are actually moving through the Universe at 370 km/s--and that's really the bottom line. The relativist argument is pure speculation based on the relativity of inertia; science says otherwise, and it's perfectly consistent with the relativity of inertia.
The last thing you talked about was the twins paradox, and it seems you want to perpetuate a much too common error about acceleration being the solution. I'll address that in one more post.