[the_roosh (OP)]

I've written a philosophy of science syle paper on the "Problem of Time" in Quantum Gravity. It still needs a lllooooottttt of work, but the ideas are fleshed out and it is those I would like to discuss, just to how they stand up to scrutiny and where they fall down.

If you want a copy of the paper, or a link to it on google drive you can PM me, as external links can't be posted.

A brief summary of the ideas follows. Everything is fleshed out in much more detail in the paper, the "conclusion" section here doesn't represent the actual conclusion section of the paper, it was just included here for the sake of fomatting. Also, I don't hurry through the "consequences" as I do here.

It's primarily the ideas I would like to discuss here, but if anyone can offer guidance on structure and formatting please PM me, as I know it needs tons of work in that regard.


tl;dr:
Time is a system of measurement - in the sense that the metric system is a system of measurement - it is neither fundamental nor emergent; it is not a dimension of the universe. This resolves "the Probem of Time" in Quantum Gravity.

Summary:

If we extend the Galilean principle of relativity to clock synchronisation and simultaneity - there is no experiment that can determine simultaneity or synchronisation - in Einsteinian Relativity, the notion of Relativity of Simultaneity becomes unjustifiable.

In his 1905 paper Einstein effectively states that the simultaneity of events in the "stationary" frame must be assumed - this follows from the fact that his synchronisation convention is established "by definition".

Synchronisation Convention

If we consider the clock synchronisation thought experiment:
the observer in the "stationary" frame is located at the mid-point between 2 clocks. A co-located emitter sends a light pulse to each clock (to start them ticking). The light pulses are reflected to the observer at the mid-point and arrive simultaneously. The observer concludes that their clocks are synchronised because they know the speed of light and the distance to the clocks, and because the light pulses returned simultaneously.

While the observer in the "stationary" frame is performing this clock synchronisation, they observe a relatively moving observer perform the exact same synchronisation process. They are also located midway between 2 clocks. The light pulses are sent to each clock and reflected; crucially, the "stationary" observer sees the light pulses hit each clock not-simultaneously, get reflected, and arrive at the "moving" observer simultaneously. The "moving" observer concludes that their clocks are synchronised. The "stationary" has observed that the clocks are not synchronised.

Here, in the original thought experiment, we are provided with a clear case of why the assumption of synchronisation/simultaneity is unjustified. The oberver in the "stationary" frame observes the "moving" observer perform the exact same synchronisation procedure, with the light pulses simultaneously returning to the mid=point, yet, the clocks are not synchronised. This should, at the very least, cause the 'stationary" observer to question whether their clocks are in fact synchronised.

Imagine, on top of this, both observers are wearing body cameras and record footage of their counterparts synchronisation attempts. They then send the footage to each other - by light signal. Each observer will be presented with observational evidence that their clocks are not synchronised.

The reasonable conclusion in this scenario would be to accept that each was mistaken in their assumption about the simultaneity of the clock synchronisation events, give the observational evidence to the contrary.

Constant Speed of Light
The tendency might be to refer back to Einstein's 2nd postulate about the constancy of the speed of light, as justification for maintaing the assumption of simultaneity/synchronisation - in spite of the observational evidence; but here too we can offer a more parsimonious interpretation.

Light Clock Thought Experiment
For this, we need only consider the thought experiment involving each observer carrying a single light clock - a photon bouncing between mirrors. The "stationary" assumes thata their clock is ticking normally, while they observe the "moving" clock as ticking slowly, as the photon travels a longer, diagonal path between the 2 mirrors.

Again, imagine each exchanging bodycam footage and being presented with evidence that their own clock is also ticking slowly. It makes sense to both observers. They only ever observe the vertical velocity component of the photon. This would be true whether they are "stationary" or ""moving" and whether the photon traced the longer diagonal path, or not.

What about the speed of light? If they measure the speed of light in the light clock, will they not measure it as having a slower speed, if they can only detect the vertical velocity component?

To answer this imagine that each tries to measure the speed of light. How will they perform the measurement only by using their trusty light clock to count the time. The issue should be apparent. Any attempt to measure the speed of light will always yield the same value because their clock will be biased by the same factor.

Conclusion
The above highlights the circular reasoning in the Einsteinian interpretation. It is the assumption of the simultaneity of events in the "stationary" frame which leads to the conclusion of the Reativity of Simultaneity.  As has been illustrated, the simultaneity of events in the "stationary" frame is an assumption; an unjustified (dare I say unjustifiable) assumption, which leads to the conclusion of RoS, thereby assuming the conclusion.

Introducing bodycam footage leaves with the assumption of simultaneity in "stationary" frames vs observational evidence to the contrary. This represents a class of evidence that cannot be explained under the Einsteinian interpretation.

Consequences
This restores absolute time and simultaneity to relativity, aligning the conceptualisations of time in QM and GR.

Absolute time is indistinguishable from a timeless universe. Clocks provide units of comparison - they don't measure a background phenomenon called "time". "Time" then is a system of measurement, much like the metric system, neither of which are fundamental or emergent. In this way, time cannot be said to form part of a background structure. This removes the issue of background dependence in Quantum Mechanics which is one of the issues in unifying QM and GR.

[Halc]

In his 1905 paper Einstein effectively states that the simultaneity of events in the "stationary" frame must be assumed

I don't think Einstein would have referred to any frame as 'the stationary' frame in his 1905 paper.  If your posts here are going to misrepresent the ideas of others, then your reasoning is fallacious.

If we consider the clock synchronisation thought experiment:
the observer in the "stationary" frame is located at the mid-point between 2 clocks. A co-located emitter sends a light pulse to each clock (to start them ticking). The light pulses are reflected to the observer at the mid-point and arrive simultaneously. The observer concludes that their clocks are synchronised because they know the speed of light and the distance to the clocks, and because the light pulses returned simultaneously.

While the observer in the "stationary" frame is performing this clock synchronisation, they observe a relatively moving observer perform the exact same synchronisation process. They are also located midway between 2 clocks.

Cutting in here.  It is not specified, but it seems that you are envisioning the first two clocks not moving relative to the first observer, and these are two different clocks that are not moving relative to the second observer.  The situation then is entirely symmetrical. Two pairs of clocks, each pair synchronized in the frame in which the pair is stationary. If this is not the case, you need to say so.

The "moving" observer concludes that their clocks are synchronised. The "stationary" has observed that the clocks are not synchronised.

More to the point, each observer concludes that the pair of clocks stationary relative to themselves are synchronized, and each observer concludes that the other pair of moving clocks are not.  Again, entirely symmetrical.

Here, in the original thought experiment, we are provided with a clear case of why the assumption of synchronisation/simultaneity is unjustified.

The symmetry says it is entirely justified.

OK, so you are a relativity denier. That also wasn't clear at first. Maybe you just don't understand, but you are writing a paper somewhere, so you presumably think that you know this stuff.

The oberver in the "stationary" frame observes the "moving" observer perform the exact same synchronisation procedure, with the light pulses simultaneously returning to the mid=point, yet, the clocks are not synchronised. This should, at the very least, cause the 'stationary" observer to question whether their clocks are in fact synchronised.

They're not in his frame, and his clocks are not synchronized in the other observer's frame.  There is no 'the stationary' frame.  There's just this frame and that one.

Imagine, on top of this, both observers are wearing body cameras and record footage of their counterparts synchronisation attempts. They then send the footage to each other - by light signal. Each observer will be presented with observational evidence that their clocks are not synchronised.

That's fine since neither expects their own clocks to be synchronized in a different frame.  This additional footage evidence is not required.

The reasonable conclusion in this scenario would be to accept that each was mistaken in their assumption about the simultaneity of the clock synchronisation events, give the observational evidence to the contrary.

The simultaneity of all those events is frame dependent.  That's what relativity of simultaneity means.

Light Clock Thought Experiment
For this, we need only consider the thought experiment involving each observer carrying a single light clock - a photon bouncing between mirrors. The "stationary" assumes thata their clock is ticking normally, while they observe the "moving" clock as ticking slowly, as the photon travels a longer, diagonal path between the 2 mirrors.

Again, imagine each exchanging bodycam footage and being presented with evidence that their own clock is also ticking slowly. It makes sense to both observers.

That it does.  The theory again predicts this, so the neither observer needs bodycam evidence from the other to show what he already knows.

What about the speed of light? If they measure the speed of light in the light clock, will they not measure it as having a slower speed, if they can only detect the vertical velocity component?

The vertical component is easily deduced with simple trigonometry.  Light moving horizontal for instance has zero vertical velocity component.

Any attempt to measure the speed of light will always yield the same value because their clock will be biased by the same factor.

Another absolutist joins the ranks.  You have plenty of company here.

If you think clocks are biased, how biased are they?  For instance, how long does it really take for Earth to make one sidereal rotation (on average)?  The biased clock in Greenwich says ~23:56:04.  What is it really?  If you can't answer it, then your bias argument falls apart.

Absolute time is indistinguishable from a timeless universe. Clocks provide units of comparison - they don't measure a background phenomenon called "time".

OK, so maybe you don't like absolute time either.  Clocks indeed provide units of comparison, as do meter sticks. That doesn't means I get no information from a clock. The timeless conclusion doesn't follow any more than a conclusion that my meter stick is dimensionless because its length is frame dependent.

Conclusion
The above highlights the circular reasoning in the Einsteinian interpretation. It is the assumption of the simultaneity of events in the "stationary" frame which leads to the conclusion of the Reativity of Simultaneity.

Strawman fallacy.  Einstein assumes no special 'the stationary' frame in special relativity.

[the_roosh (OP)]

I don't think Einstein would have referred to any frame as 'the stationary' frame in his 1905 paper.  If your posts here are going to misrepresent the ideas of others, then your reasoning is fallacious.

In order to render our presentation more precise and to distinguish this system of co-ordinates verbally from others which will be introduced hereafter, we call it the “stationary system.” (Einstein, 1905).

Cutting in here.  It is not specified, but it seems that you are envisioning the first two clocks not moving relative to the first observer, and these are two different clocks that are not moving relative to the second observer.  The situation then is entirely symmetrical.

Apologies, I am assuming familiarity with the clock synchronisation thought experiment here - I am more explicit in the paper. But yes, an observer at rest relative to 2 clocks, equidistant from each clock. As Einstein did, we can refer to this as "the stationary system" with the 'stationary clocks".

There is also a relatively moving observer with 2 clocks in the "moving system" - we are considering things only from one perspective, for the time being.

Two pairs of clocks, each pair synchronized in the frame in which the pair is stationary. If this is not the case, you need to say so.

This is the crux of the issue. The idea that they are synchronised is purely an assumption and, as is being argued, an unjustified/unjustifiable assumption.
We establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A.we establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A. (Einstein, 1905).

More to the point, each observer concludes that the pair of clocks stationary relative to themselves are synchronized, and each observer concludes that the other pair of moving clocks are not.  Again, entirely symmetrical.

Again, this is the crux of the issue! They conclude that the "stationary clocks" are synchronised. What is it that leads to this conclusion? There is no experiment that can determine the simultaneity of the clock synchronisation events, so they assume that the clocks are synchronised. Why? Because they know the speed of light, the distance to each clock, and [crucially] the light reflected from the "stationary clocks" returns to them simultaneously.

Indeed, it is the symmetry of the situation which means that their assumption about the simultaneity of the clock events is unjustified. They observe their counterpart conduct the exact same synchronisation procedure, with the exact same observational evidence - distance to each clock, speed of light, and light pulses returning simultaneously. Yet, the "moving" clocks are not synchronised. The symmetry of the situation should lead the "stationary" observer to at least question the assumption of simultaneity/synchronisation of their clocks.

The symmetry says it is entirely justified.

It is the assumption of simultaneity in their own frame, which is not justified.

OK, so you are a relativity denier. That also wasn't clear at first. Maybe you just don't understand, but you are writing a paper somewhere, so you presumably think that you know this stuff.

Not a denier, just advocating for a different, more parsimmonious interpretation. It is similar to the Lorentz-Poincare interpretation except that it is a timeless interpretation.

They're not in his frame, and his clocks are not synchronized in the other observer's frame.  There is no 'the stationary' frame.  There's just this frame and that one.

The point is that the observer in the "stationary system" sees the relatively moving observer perform the exact same syncronisation procedure, with the exact same observational results but the moving clocks fail to synchronise. How does the "stationary" observer know that the exat same issue isn't afflicting their own synchronisation procedure? They don't because, in keeping with the Galilean Priniciple of Relativity, there is no experiment they can conduct to determine that their clocks are actually synchronised or that events are simultaneous, in their frame.

That's fine since neither expects their own clocks to be synchronized in a different frame.  This additional footage evidence is not required.

The bodycam footage represents observationl evidence that their clocks are not synchronised versus their assumption that their clocks are synchronised. The reasonable conclusion is that each observer is mistaken in their assumption of the simultaneity/synchronisation of their clocks, given the observational evidence to the contrary.

The simultaneity of all those events is frame dependent.  That's what relativity of simultaneity means.

The notion of relativity of simultaneity follows from the unjustified assumption that the simultaneity of events can be determined in any frame. That is, it starts by assuming that events are simultaneous in a given frame, when no such determination can be made. Without this assumption of simultaneity, RoS doesn't get off the ground.

That it does.  The theory again predicts this, so the neither observer needs bodycam evidence from the other to show what he already knows.

The bodycam footage shows that the assumption, by the observer in the "stationary system", that the photon in their clock travels a perpendicular distance between the mirrors, is unjustified.

The vertical component is easily deduced with simple trigonometry.  Light moving horizontal for instance has zero vertical velocity component.

The point is that, as per the Galilean Principle of Relativity, the observer in the "stationary system" will always observe only the vertical velocity component of the photon and has no way off knowing if it has a horizontal component. This would be the case if they were "stationary" or "moving"; if the photon traced the perpendicular distancce between mirrors, or the longer diagonal distance.

If you think clocks are biased, how biased are they?  For instance, how long does it really take for Earth to make one sidereal rotation (on average)?  The biased clock in Greenwich says ~23:56:04.  What is it really?  If you can't answer it, then your bias argument falls apart.

Perhaps I don't see the relevance. The point I was making is that the 2nd postulate can be interpreted to mean that it is the measurement of the speed of light that is constant. Einstein's own thought experiment shows us how nature would "conspire" against us to ensure that we always measure the same speed of light.

As per the thought experiment, if the oberver tries to measure the speed of light in their light clock they will have to use another light clock - the circularity should be apparent. This circularity is the "conspiracy"

OK, so maybe you don't like absolute time either.  Clocks indeed provide units of comparison, as do meter sticks. That doesn't means I get no information from a clock. The timeless conclusion doesn't follow any more than a conclusion that my meter stick is dimensionless because its length is frame dependent.

Without the assumpion of relativity of simultaneity we are left with absolute simultaneity and absolute time. To quote Lee Smolin, "were it not for the external clock, one could already say that time has disappeared".
Google: edge.org/ lee_smolin-stuart_a_kauffman  -a-possible-solution-for-the-problem-of-time-in-quantum (for quote)

We can make time "disappear" simply by chllenging the assumption that "a clock measures [a background phenomenon called] time". If we examine the processes of a clock, nowhere is this background phenomenon actually measured. Instead, a clock is the measurement of the change in some system e.g. the microwave emissions of caesium atoms. Clocks count cycles and these cycles act as standard units of comparison or units of measurement.

In this way, time can be said to be nothing more than a system of measurement. Just as the metric system is neitherr fundamental nor emergent, neither is timmee

Strawman fallacy.  Einstein assumes no special 'the stationary' frame in special relativity.

His actual phrasing was "stationary system" but it''s the same difference.

[Halc]

I don't think Einstein would have referred to any frame as 'the stationary' frame in his 1905 paper.  If your posts here are going to misrepresent the ideas of others, then your reasoning is fallacious.

In order to render our presentation more precise and to distinguish this system of co-ordinates verbally from others which will be introduced hereafter, we call it the “stationary system.” (Einstein, 1905).

I stand corrected then.  He is labeling the frames, for convenience, as 'stationary' and 'moving' then.  So long as there is no assertion about the stationary one being in some way special (which would violate the first principle), this is acceptable.

Apologies, I am assuming familiarity with the clock synchronisation thought experiment here

I'm not familiar actually, but I think I worked it out.  Your description of how the clocks are synced describe a valid method to perform the task.

There is also a relatively moving observer with 2 clocks in the "moving system" - we are considering things only from one perspective, for the time being.

Fine.

Two pairs of clocks, each pair synchronized in the frame in which the pair is stationary. If this is not the case, you need to say so.

This is the crux of the issue. The idea that they are synchronised is purely an assumption and, as is being argued, an unjustified/unjustifiable assumption.

Agree, and I didn't say that they were synchronized.  I said each pair was synchronized in a specific frame, and not in the other.  If you consider that an assumption, well, I suppose it could be, especially if we have a different interpretation of what it means for clocks to be synchronized.

We establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A.(Einstein, 1905).

That's pretty out of context.  The definition of what?  From reading the quote, it seems to be the definition of points in space (A and B), and points in space require a frame for their definition.

More to the point, each observer concludes that the pair of clocks stationary relative to themselves are synchronized, and each observer concludes that the other pair of moving clocks are not.  Again, entirely symmetrical.

Again, this is the crux of the issue! They conclude that the "stationary clocks" are synchronised.

Yes, but different pairs of clocks are stationary relative to the frames of each observer.

What is it that leads to this conclusion? There is no experiment that can determine the simultaneity of the clock synchronisation events, so they assume that the clocks are synchronised.

You described in your OP a simple experiment to do just that.  Light from stationary equidistant clocks emitted at the two synchronization events are observed simultaniously.  That's an empirical verification if I ever saw one.

Why? Because they know the speed of light, the distance to each clock, and [crucially] the light reflected from the "stationary clocks" returns to them simultaneously.

Sorry, but it seems you contradict yourself.  They know all these things, yet you say it cannot be known.

Indeed, it is the symmetry of the situation which means that their assumption about the simultaneity of the clock events is unjustified. They observe their counterpart conduct the exact same synchronisation procedure, with the exact same observational evidence - distance to each clock, speed of light, and light pulses returning simultaneously. Yet, the "moving" clocks are not synchronised.

Nobody ever said they were.
You confuse 'sychronized' with 'synchronized in frame X'.  I notice you drop the frame references whenever it's convenient to your point.  The only way two clocks can be synchronized (no frame reference) is if they follow the same worldline, essentially being the same clock.

The symmetry of the situation should lead the "stationary" observer to at least question the assumption of simultaneity/synchronisation of their clocks.

They do question it, but all observers are right.  Their clocks are synchronized in their frames, as they empirically verified.

Not a denier, just advocating for a different, more parsimmonious interpretation. It is similar to the Lorentz-Poincare interpretation except that it is a timeless interpretation.

OK, that's valid.  If it makes no different predictions, what's the advantage of the interpretation?  Does it simplify anything that's more complicated in the relative interpretation?  You call it parsimonious, like it perhaps requires less effort in some way.

The point is that the observer in the "stationary system" sees the relatively moving observer perform the exact same syncronisation procedure, with the exact same observational results but the moving clocks fail to synchronise.

Again, the intentional drop of the frame reference.  The moving clocks do very much synchronize in the second frame.  He did not fail at all.

How does the "stationary" observer know that the exat same issue isn't afflicting their own synchronisation procedure?

He is afflicted.  Symmetry demands it.  His clocks are similarly not synchronized in the other frame.

They don't because, in keeping with the Galilean Priniciple of Relativity, there is no experiment they can conduct to determine that their clocks are actually synchronised or that events are simultaneous, in their frame.

Galilean PoR doesn't say that.  It says what can be done in one frame can be done in another, and since there is very much an empirical verification that can be performed (which you describe in your OP), both observers can verify that their clocks are actually synchronised or that events are simultaneous, in their frame.

And I thank you for keeping the frame reference that time.  The italics was a nice touch.

The notion of relativity of simultaneity follows from the unjustified assumption that the simultaneity of events can be determined in any frame. That is, it starts by assuming that events are simultaneous in a given frame, when no such determination can be made.

But you show how to determine it.  It isn't hard.  I totally don't understand this assertion that given a frame, ordering of events cannot be determined. The assumption you speak of isn't made ever. It is a conclusion at best.

The point is that, as per the Galilean Principle of Relativity, the observer in the "stationary system" will always observe only the vertical velocity component of the photon and has no way off knowing if it has a horizontal component.

He does have a way.  If it had a horizontal component, the light wouldn't come back to the  detector that is stationary in that frame.

As per the thought experiment, if the oberver tries to measure the speed of light in their light clock they will have to use another light clock - the circularity should be apparent. This circularity is the "conspiracy"

They're up front about that.  A light clock by definition cannot be used to measure light speed, yes.  It would take some other sort of clock.  Light speed was initially measured using another reliable clock that could be moved closer and further away.  It was an inertial clock (a steadily rotating thing like Earth), not based on light at all.

OK, so maybe you don't like absolute time either.

Without the assumpion of relativity of simultaneity we are left with absolute simultaneity and absolute time.

Or maybe I got that wrong....

We can make time "disappear" simply by chllenging the assumption that "a clock measures [a background phenomenon called] time".

No, relativity has no background standard.  That was my point about building a device that cancels out its own bias.  Relativity cares not about that background and doesn't assume it at all.  It just cares that this duration is somehow comparable to that other duration over there, but never to a base rate.

If we examine the processes of a clock, nowhere is this background phenomenon actually measured.

Exactly, yes.

Strawman fallacy.  Einstein assumes no special 'the stationary' frame in special relativity.

His actual phrasing was "stationary system" but it''s the same difference.[/quote]
As a notational convenience, yes he said that.  It was not to make that frame in any way special/preferred.

[the_roosh (OP)]

I stand corrected then.  He is labeling the frames, for convenience, as 'stationary' and 'moving' then.  So long as there is no assertion about the stationary one being in some way special (which would violate the first principle), this is acceptable.

I make a separate point about this in the paper, but it is more of an aside,  so there's no need to go into it here.

Agree, and I didn't say that they were synchronized.  I said each pair was synchronized in a specific frame, and not in the other.  If you consider that an assumption, well, I suppose it could be, especially if we have a different interpretation of what it means for clocks to be synchronized.

This is the crux of the issue. The Simultaneity/synchronisation in the stationary frame i.e. in his frame is assumed. I will clarify below. And we have the same definition.

that's pretty out of context.  The definition of what?  From reading the quote, it seems to be the definition of points in space (A and B), and points in space require a frame for their definition.

The definition is [to paraphrase] that the journey time from A to B equals the journey time from B to A. It has to be assumed bcos to actually measure it would require synchronised clocks - see the issue. It is the reason that the 1-way speed of light cannot be measured.

You described in your OP a simple experiment to do just that.  Light from stationary equidistant clocks emitted at the two synchronization events are observed simultaniously.  That's an empirical verification if I ever saw one.

The returning light pulses are observed simultaneously. But the observer in the "stationary system" observes the light return simultaneously to the "moving" observer also, this is despite the fact that the "moving" clocks are not synchronised, from the perspective of the "stationary" observer.

This demonstrates to the "stationary" observer that the light would return [to him] simultaneously even if his clocks are not synchronised. He is simply assuming that they are synchronised in his frame.

The bodycam footage represents observational evidence that the clocks are not synchronised,  versus his assumption that they are.

Sorry, but it seems you contradict yourself.  They know all these things, yet you say it cannot be known.

If it is known, then it must be known that light pulses will return simultaneously whether clocks are synchronised or not. This highlights the fact that Simultaneity  of the Synchronisation events - in the stationary frame - is assumed.

The bodycam footage represents observational evidence which contradicts that assumption

Nobody ever said they were.
You confuse 'sychronized' with 'synchronized in frame X'.  I notice you drop the frame references whenever it's convenient to your point.  The only way two clocks can be synchronized (no frame reference) is if they follow the same worldline, essentially being the same clock.

Given the symmetry, we only need to talk about the perspective from the "stationary" frame - so the frame can be assumed. Apologies, if that wasn't clear.

They do question it, but all observers are right.  Their clocks are synchronized in their frames, as they empirically verified.

All observers are right and by extension all observers are also wrong. If it weren't for the circularity of the reasoning ensuring that the interpretation is self consistent, this woul be a paradox in anyone's language- but not for relativity!

There is, of course, an alternative, non-paradoxical case where all observers are right and simultaneously wrong. That is, they are wrong in their assumption of Simultaneity in their own frame but right about the non-simultaneity observed in the relatively moving frame.

OK, that's valid.  If it makes no different predictions, what's the advantage of the interpretation?  Does it simplify anything that's more complicated in the relative interpretation?  You call it parsimonious, like it perhaps requires less effort in some way.

It's more parsimonious bcos it makes fewer assumptions and it is simpler bcos it doesn't involve paradoxical scenarios where observers are both right and wrong, and it eliminates the Relativity of Simultaneity.

Again, the intentional drop of the frame reference.  The moving clocks do very much synchronize in the second frame.  He did not fail at all.

In case the point still hasn't been clearly made:

The "stationary" observer witnesses an alternative explanation for the simultaneous return of the light pulses. They see that the light pulses return simultaneously whether clocks are synchronised or not.

The bodycam footage offers empirical evidence that their clocks, in their localised region of space, are not synchronised. This contradicts their assumption that the clocks are synchronised in their own frame.

He is afflicted.  Symmetry demands it.  His clocks are similarly not synchronized in the other frame.

His clocks reside in his own frame. He assumes that they are synchronised. The relatively moving observer provides observational evidence that the clocks, in his localised region of space, are not synchronised.

Simply ask the question: is it possible that the observer in the stationary frame is mistaken about the simultaneity of the clock synchronisation events? Given that they see a scenario where light returns simultaneously from non-synchronised clocks.

Galilean PoR doesn't say that.  It says what can be done in one frame can be done in another, and since there is very much an empirical verification that can be performed (which you describe in your OP), both observers can verify that their clocks are actually synchronised or that events are simultaneous, in their frame.

The idea is that we can extend principle to Simultaneity and synchronization - there is no experiment that can determine the Simultaneity of events.

Both assume their clocks are synchronised because the light pulses return simultaneously, from the clocks. They see, from viewing the relatively moving observer, that the light pulses will return simultaneously even if the clocks do not synchronise.

But you show how to determine it.  It isn't hard.  I totally don't understand this assertion that given a frame, ordering of events cannot be determined. The assumption you speak of isn't made ever. It is a conclusion at best.

Hopefully I  have now shown that it is the simultaneous return of light pulses that leads them to assume (not determine) the Simultaneity of synchronization events. The light pulses return simultaneously whether the clocks are synchronised or not.

He does have a way.  If it had a horizontal component, the light wouldn't come back to the  detector that is stationary in that frame.

Talking about the single light clock with the photon bouncing between mirrors.

Essentially, the observer in the "stationary system" observers the "moving" observer with the photon in the light clock having both a vertical and horizontal velocity component. They are presented with observational evidence that the very same is true for the photon in their clock - they have no way of determining this.

They're up front about that.  A light clock by definition cannot be used to measure light speed, yes.  It would take some other sort of clock.  Light speed was initially measured using another reliable clock that could be moved closer and further away.  It was an inertial clock (a steadily rotating thing like Earth), not based on light at all.

An observer moving relative to the Earth cannot use the Earth. Of course, if they did their motion relative to the earth would cancel out the effect, by way of biasing their clock.

The point is, if every clock is biased by the same factor,  then it will all cancel out, as though the universe is "conspiring" to ensure the speed of light is always measured to have the same value.

]No, relativity has no background standard.  That was my point about building a device that cancels out its own bias.  Relativity cares not about that background and doesn't assume it at all.  It just cares that this duration is somehow comparable to that other duration over there, but never to a base rate.

Special Relativity is a background dependent theory,  General Relativity is not. If a clock doesn't measure some background phenomenon called "time" then clocks simply count units of measurement, like a tape measure counts metres. This makes "time" nothing more than a system of measurement just like the metric system. Therefore, time is neither fundamental nor emergent,  just as the metric system isn't.

As a notational convenience, yes he said that.  It was not to make that frame in any way special/preferred.

As mentioned, there is a separate argument in the paper on this point, which references Leibniz's identity of indiscernibles in relation to the absolute rest frame of Newtonian Mechanics.

It's not the main thrust of the argument, so I won't go into it here. It's just another one of the issues with the Einsteinian interpretation.

[Halc]

The definition is [to paraphrase] that the journey time from A to B equals the journey time from B to A.

That is a statement, and not one that defines anything.  The statement is not true in general.  A and B can be objects and have differing times for the light journeys due to the fact that objects are not obliged to stay put.
That's why I had to look up the quote to see what definition was being referenced.

It has to be assumed bcos to actually measure it would require synchronised clocks - see the issue. It is the reason that the 1-way speed of light cannot be measured.

Wrong.  Again, the earliest light speed measurement was done one way, and while it employed multiple clocks, they were not particularly synchronized.

The returning light pulses are observed simultaneously. But the observer in the "stationary system" observes the light return simultaneously to the "moving" observer also, this is despite the fact that the "moving" clocks are not synchronised, from the perspective of the "stationary" observer.

The first observer sees that the moving clocks are not the same distance from the other observer when they're zeroed.  That's why they're not synced in that frame.

This demonstrates to the "stationary" observer that the light would return [to him] simultaneously even if his clocks are not synchronised. He is simply assuming that they are synchronised in his frame.

They are verified in sync because he can measure that his clocks are equidistant from him, while the two moving-clock synchronization events are not equidistant from the moving observer, thus they must not be in sync.

You say you know your relativity, but I'm arguing some pretty basic points with you.  How can you write a paper with this level of knowledge of the subject?

If it is known, then it must be known that light pulses will return simultaneously whether clocks are synchronised or not

This statement is nonsense.  If two sources emit light simultaneously from different distances, the near one will be observed first.  Ditto if I do it with mirrors at different distances and the light source originates by me.

Given the symmetry, we only need to talk about the perspective from the "stationary" frame - so the frame can be assumed. Apologies, if that wasn't clear.

Fine then.  The moving clocks are not synchronized in that frame, and the all observers agree with that fact.  There's no conflict.

It's more parsimonious bcos it makes fewer assumptions

Fewer than two?  What one assumption does your interpretation make?

and it is simpler bcos it doesn't involve paradoxical scenarios where observers are both right and wrong,

There's no paradox to remove.

and it eliminates the Relativity of Simultaneity.

That it does.  Seems to make everything more complicated to do so, but it does indeed eliminate that.

In case the point still hasn't been clearly made:

The "stationary" observer witnesses an alternative explanation for the simultaneous return of the light pulses. They see that the light pulses return simultaneously whether clocks are synchronised or not.

In this particular case yes.  Not always, as I point out above.

The bodycam footage offers empirical evidence that their clocks, in their localised region of space, are not synchronised.

What do you mean 'localized'?  The clocks are separated, not local to each other.  If they were local, they'd be synced in any frame.

This contradicts their assumption that the clocks are synchronised in their own frame.

How?  You didn't say that they were shown to be not synchronized in that frame.  No footage demonstrated that.  I see no contradiction.

His clocks reside in his own frame. He assumes that they are synchronised.

No he doesn't.  Nobody assumes clocks are synchronized.  They demonstrate (not assume) that they're synchronized in their own frame, but not that they're synchronized.  Again, the distinction between those wordings escapes you, or you're being deliberate about it. Ignorance or troll?  You interpret relativistic statements as absolute ones, and then find conflict.  Indeed, the interpretations don't mix.

Simply ask the question: is it possible that the observer in the stationary frame is mistaken about the simultaneity of the clock synchronisation events? Given that they see a scenario where light returns simultaneously from non-synchronised clocks.

The question lacks frame references, so is largely meaningless.

Both assume their clocks are synchronised

No they don't.  They're not absolutists, so they make no absolute assumptions like that. In all probability, none of the 4 clocks is synchronized in an absolute way since none of them attempted an absolute procedure to do it.  Why should they?  It serves no purpose.

Light speed was initially measured using another reliable clock that could be moved closer and further away.  It was an inertial clock (a steadily rotating thing like Earth), not based on light at all.

An observer moving relative to the Earth cannot use the Earth.

The observer was on Earth.  There was little choice in the matter at the time.

The point is, if every clock is biased by the same factor,  then it will all cancel out, as though the universe is "conspiring" to ensure the speed of light is always measured to have the same value.

They're not all biased out by the same factor.  They're all dilated to some extent for multiple reasons.

clocks simply count units of measurement, like a tape measure counts metres.

Agree, the units are arbitrary.  No alien is going to come up with a meter or a second.  That doesn't mean spacetime isn't fundamental.  Just that the units into which we choose to slice it up are not.

BTW, I don't think they're fundamental either.  I just disagree with the validity of the argument you use to conclude that.

[the_roosh (OP)]

Before I reply Halc, I do genuinely want to thank you for taking the time to discuss the ideas. I hope that my tone doesn't come across as adversarial bcos that is not, at all, how I intend it. I tend to have a very forthright style of debate which is more a matter of habit. I am aware of how this might sometimes come across.

With that being said, I would like to try a slightly different track to see if I can clarify the point I am trying to make. I will outline some issues where I think we might be talking past each other. I will respond to your detailed reply below (in case my attempt to clarify the issue doesn't work).


=============
Cross purposes
=============

1) We can assume the reference frame to be that of "the stationary system". This is because, given the symmetry of the situation, both observers consider themselves to be in "the stationary system".

2) The contention here isn't that the Einsteinian interpretation isn't self-consistent. I [finally*] accept that it is self-consistent. You have made a few statements to the effect that there is no "conflict" or that "all observers agree**". The intention isn't to demonstrate a conflict or contradiction in the Einsteinian interpretation.

3) The point that is being attempted, is to demonstrate that there is an [unjustified] assumption being made in the Einsteinian interpretation. That assumption is that observers in "the stationary frame" assume that their clocks are synchronised (in their own frame of reference).

4) You have made repeated references to the frame dependence of simultaneity. The point being made is that, without the assumption of #3
above, one cannot arrive at a conclusion of frame dependent simultaneity.

5) Simultaneity of events in the "stationary system" is an assumption, while the bodycam footage represents observational evidence to the contrary.

* I say finally bcos it took me years to accept the self-consistency of relativity. It was only once I finally got my head around the self-consistency and gave up on trying to find the contradiction that the underlying assumption [of simultaneity in the "stationary system"] became apparent.

** I address this point in the reply to the main post.


=============
Change of track
=============

As mentioned, I would like to try a slightly different approach to see if I can clarify the point I am trying to make. I will reply to your points below.

I want to try and clarify the point by means of the inner monologue of one of the observers. I think it will also be heplful to name our observers - good ol' Alice and Bob - because it will make it easier to keep track of reference frames. (Plus, the human mind seems to have an easier time when there are "characters" involved).


===============
Alice's Monologue
===============
Ok, I've got my clock synchronization procedure set up.
I have my emitter midway between my clocks and I've measured to make sure that they are equidistant from the emitter.

Oh look, there's Bob, moving relatively. It looks like he is trying to synchronise his clocks as well. He's got his emitter set up, oh and he's measuring to make sure it is equidistant from each clock.
He's got the exact same set-up as me.
That will be cool, that we will both have synchronised clocks. I'll take a video with my bodycam and share it with him on social media.

Ok, time to send the light pulses. Oh look, he's done the same.
Oh, but the clock at the rear of his train is moving towards the light pulse while the clock at the front is moving away from it. The silly goose! His clocks are not synchronised, I had better show him the video to let him no.

Oh look, the light pulses returned to me simultaneously, that means my clocks must be synchronized.

Oh but wait! The light pulses also returned to Bob simultaneously, that means he will think his clocks are synchronized. Wait till I show him the video.

Hold on a minute, if the light pulses returned to him simultaneously but I can see that his clocks didn't synchronise, is it possible, despite the fact that the light pulses returned to me simultaneously, that my clocks aren't synchronised either? Surely not!

Oh but wait! Actually yes, that is a very distinct possibility because I have no way of determining if that is the case or isn't. I have just assumed that they are synchronised because I "establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A." (Einstein, 1905).

Oh look, here is a video from bob; it's his bodycam footage showing observational evidence that my clocks are not synchronised.

How does my assumption look now?

==============
Response to post
==============

That is a statement, and not one that defines anything.  The statement is not true in general.  A and B can be objects and have differing times for the light journeys due to the fact that objects are not obliged to stay put.
That's why I had to look up the quote to see what definition was being referenced.

We have not defined a common “time” for A and B, for the latter cannot be defined at all unless we establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A. (Einstein, 1905).
It can't be any more explicit that what is being defined is the time required by light to travel from A to B equals the “time” it requires to travel from B to A, this is required to establish a "common time for A and B" i.e. to synchronise A and B.

Wrong.  Again, the earliest light speed measurement was done one way, and while it employed multiple clocks, they were not particularly synchronized
.

The "one-way" speed of light, from a source to a detector, cannot be measured independently of a convention as to how to synchronize the clocks at the source and the detector. What can however be experimentally measured is the round-trip speed (or "two-way" speed of light) from the source to the detector and back again. Albert Einstein chose a synchronization convention (see Einstein synchronization) that made the one-way speed equal to the two-way speed... Experiments that attempted to directly probe the one-way speed of light independent of synchronization have been proposed, but none has succeeded in doing so.
(Wiki: one-way speed of light)

The first observer sees that the moving clocks are not the same distance from the other observer when they're zeroed.  That's why they're not synced in that frame.

Again, this is the heart of the problem. The first observer, Alice, has no way of determining that the very same is not true for her own clocks - in her own reference frame. Indeed, the observational evidence, in the form of the bodycam footage, suggests that the same is true for her clocks also, on the platform.

They are verified in sync because he can measure that his clocks are equidistant from him, while the two moving-clock synchronization events are not equidistant from the moving observer, thus they must not be in sync.

You're conflating two different things here, the distance from the observer to each clock and the distance from the two "moving-clock synchronization events" to the moving observer. You are somewhat mistaken though, bcos the moving observer, Bob, is equidistant from the clocks and therefore from the "moving-clock synchronization events".

I think what you mean is that the light pulse travels a shorter distance to one clock than the other. Again, the point is that the Alice has no way of knowing that the exact same is not true for her synchronization events. In both cases (synchronised and not synchronised), the light returns simultaneously bcos, while one photon travels a shorter distance to the clock than the other, this is exactly cancelled on the return leg, back to the mid-point.

Fine then.  The moving clocks are not synchronized in that frame, and the all observers agree with that fact.  There's no conflict.

The point that "all observers agree with that fact" is a bit misleading. One of the ways in which the Einsteinian interpretation resolves the obvious disagreement is by allowing there to be disagreements between observers.

Think it through, if Alice and Bob were to agree with all the statements that relativity makes, then Alice would agree that, according to Bob, his clocks are synchronised. She would do this despite not actually observing it. This is just applying the same assumption at a higher order of cognition.

There's no paradox to remove.

and it eliminates the Relativity of Simultaneity.

That it does.  Seems to make everything more complicated to do so, but it does indeed eliminate that.

I know it might seem that because the Einsteinian interpretation is self consistent, that there are no paradoxes, but in anyone's language, where an observer can be both right and wrong about events in the physical world, where a ladder can both be too big to fit in a garage and small enough to fit completely, and where "time" on board a train can tick at an infinite number of different rates and when one clock can tick both slower and faster than another clock, those are paradoxes in anyone's language.

The experimental support for relativity has lead us to accept such "spooky action" but, as has been outlined, there is an alternative, more parsimonious interpretation that doesn't necessitate those contradictions.

In this particular case yes.  Not always, as I point out above.

OK, maybe we can progress from here.

The point is that there is an alternative interpretation to the observational evidence of the clock synchronisation procedure in the frame of reference of the stationary system. That alternative interpretation simply involves dropping the assumption of simultaneity [of the synchronisation events] and accepting the observational evidence that the clocks are not synchronised i.e. the bodycam footage.

What do you mean 'localized'?  The clocks are separated, not local to each other.  If they were local, they'd be synced in any frame.

My aplogies if I have caused confusion with my use of the term "localized". It might instead be more clear to talk in terms of two locations. We have the clocks "onboard the train" and the clocks "on the platform". In this sense relativity says, the clocks onboard the train are synchronised, in the frame of the train, but not from the perspective of an observer at rest on the platform.

Because reltivity says that this is more than just the case that the clocks appear unsynchronised from the platform, it says that both statementss are equally true. Therefore, the clocks onboard the train are both synchronised with each other and not-synchronised with each other, in their physical locations onboard the train.

That is paradoxical!

How?  You didn't say that they were shown to be not synchronized in that frame.  No footage demonstrated that.  I see no contradiction.

Alice looks at bodycam footage of her clocks located on the platform. The bodycam footage shows that the clocks did not synchronise. This is observational evidence that the clocks did not synchronise.

Alice assumes that her clocks are synchronised in the face of observational evidence to the contrary.

Simply ask the question: is it possible that the observer in the stationary frame is mistaken about the simultaneity of the clock synchronisation events? Given that they see a scenario where light returns simultaneously from non-synchronised clocks.

The question lacks frame references, so is largely meaningless

I have clarified that we can assume "in the frame of the 'stationary system" given the symmetry.

To rephrase: Simply ask the question: is it possible that the observer in the stationary frame is mistaken about the simultaneity of the clock synchronisation events, in the stationary frame? Given that they see a scenario where light returns simultaneously from non-synchronised clocks.

No they don't.  They're not absolutists, so they make no absolute assumptions like that. In all probability, none of the 4 clocks is synchronized in an absolute way since none of them attempted an absolute procedure to do it.  Why should they?  It serves no purpose.

Again, we can imply "in the frame of the "stationary system". The point being contested is that simultaneity is frame dependent. An unavoiable requirement of frame dependent simultaneity is that there must be one reference frame in which events are simultaneous (otherwise there is no basis for the relativity of simultaneity). To delare that events are simultaneous in any frame simply isn't justified. To say that events are simultaneous in one frame requires us to assume that they are simultaneous in that frame.

Indeed, if you think about it, Einsteinian relativity actually advocates for a situation where one observer doggedly sticks to their assumption [of simultneity/synchronisation] in the face of an infinite number of observers providing observational evidence to the contrary. That sounds more like religion than science!

Light speed was initially measured using another reliable clock that could be moved closer and further away.  It was an inertial clock (a steadily rotating thing like Earth), not based on light at all.

An observer moving relative to the Earth cannot use the Earth.

The observer was on Earth.  There was little choice in the matter at the time.

Maybe I've misunderstood your point. We were talking about the use of clocks to measure the speed of light, in the context of the thought experiment. What clock are you suggesting that Bob use to measure the speed of light, where the effect of relative motion won't result in his clock offsettiing any discrepancy in the speed of light?

They're not all biased out by the same factor.  They're all dilated to some extent for multiple reasons.

Yes, the clocks are dilated, not "time" and this dilation will always result in Alice and Bob getting the same result when they measure the speed of light. And, in such a way that it doesn't result in the relativity of simultaneity

Agree, the units are arbitrary.  No alien is going to come up with a meter or a second.  That doesn't mean spacetime isn't fundamental.  Just that the units into which we choose to slice it up are not....BTW, I don't think they're fundamental either.  I just disagree with the validity of the argument you use to conclude that.

The metric system is neither fundamental nor emergent. "Time" is system of measurement like the metric system and so, it is neither fundamental nor emergent either. The metric system attempts to express distances in common units, time attempts to express duration in commin units.

3D space is self-evident (not to say the holographic principle isn't correct). The "dimension of time" however, is not self-evident. We only ever observe things in the present instant i.e. the "now". Therefore, we cannot - not even in principle - oberve a temporal dimension; that is, we can never observe things extended in time. Yes, things have duration [they persist, they age] duration, however, does not imply extension. This is covered in the paper.

[Halc]

1) We can assume the reference frame to be that of "the stationary system". This is because, given the symmetry of the situation, both observers consider themselves to be in "the stationary system".

If you do that, then the words 'the stationary system' do not identify a frame since each observer names a different frame with those words.  You'd have to say 'Observer A's stationary system' and 'Observer B's stationary system', which seems a lot more complicated than just saying Frame A and Frame B.
This point number 1 seems an attempt at obfuscation.  Without reading further, I know you're going to try to hide an error by creating this ambiguity.  So the words "the stationary system" no longer hold meaning in the absence of identification of whose stationary system it is.  I'm actually fine with that since I never liked the prior usage of the term that made it sound like an objective thing.

2) The contention here isn't that the Einsteinian interpretation isn't self-consistent. I [finally*] accept that it is self-consistent. You have made a few statements to the effect that there is no "conflict" or that "all observers agree**". The intention isn't to demonstrate a conflict or contradiction in the Einsteinian interpretation.

Can we drop the whole bodycam thing then?  The purpose of that seemed to be to prove a case to the other observer over some point about which they disagreed, but they agree on all points.  There is no conflict as you say.

3) The point that is being attempted, is to demonstrate that there is an [unjustified] assumption being made in the Einsteinian interpretation. That assumption is that observers in "the stationary frame" assume that their clocks are synchronised (in their own frame of reference).

In whose stationary frame?  See?  Those words are no longer meaningful without identification of which observers stationary frame.  You've not identified an observer here.
It actually does not matter which observer in your statement.  I can generalize it to this:  That assumption is that any observer assumes that his clocks are synchronised in his own frame of reference.  This is assuming of course that he's actually synchronized his clocks by some valid method, one of which you describe in your OP.

4) You have made repeated references to the frame dependence of simultaneity. The point being made is that, without the assumption of #3 above, one cannot arrive at a conclusion of frame dependent simultaneity.

Point 3 is valid, even given its ambiguous wording.  It isn't an assumption.  It is a deduction given the two premises of SR.

5) Simultaneity of events in the "stationary system" is an assumption, while the bodycam footage represents observational evidence to the contrary.

No frame identified (per point 1).  This statement is meaningless.
I knew you would make statements like this when you changed the definition like that.  I'm using the new definition, which I actually prefer, even though it is needlessly wordy.  You say in point 2 that you accept that the interpretation is consistent, but here you attempt to suggest it isn't.

I want to try and clarify the point by means of the inner monologue of one of the observers. I think it will also be heplful to name our observers - good ol' Alice and Bob - because it will make it easier to keep track of reference frames.

On loan from the QM department, eh?  Good.  I like them.  This corresponds nicely to frame A and B BTW.  'Frame A' or 'Alice's frame' seems a lot easier to say than 'Alice's stationary system', never mind the improved clarity of the former.

Alice:The silly goose! His clocks are not synchronised,

There is no meaning to 'synchronized' without a frame reference.  Alice does not say that, and Bob does not consider his clocks to be objectively synchronized as you imply.  I repeat this point in all my prior posts, and you continue to use this invalid wording.  There is no conflict between what Alice claims and what Bob claims, remember?  Yet you persist.

Oh look, the light pulses returned to me simultaneously, that means my clocks must be synchronized.

Again, no, for the same reasons.

We have not defined a common “time” for A and B, for the latter cannot be defined at all unless we establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A. (Einstein, 1905).

Einstein had defined A and B to be points in space in that quote, which is a frame dependent concept.  Thus Alice and Bob do not share common points in space.

It can't be any more explicit that what is being defined is the time required by light to travel from A to B equals the “time” it requires to travel from B to A, this is required to establish a "common time for A and B" i.e. to synchronise A and B.

Yes, but remember that A and B are frame dependent, so the above is a frame dependent statement.

Again, the earliest light speed measurement was done one way, and while it employed multiple clocks, they were not particularly synchronized.

The "one-way" speed of light, from a source to a detector, cannot be measured independently of a convention as to how to synchronize the clocks at the source and the detector.

They did just that, so your statement is obviously incorrect.  It was one way, and lacked any synchronization.  The fact that they got a pretty good figure for the speed (when before they had no clue) shows that the method is valid.  Try reading up on it.

What can however be experimentally measured is the round-trip speed (or "two-way" speed of light) from the source to the detector and back again.

That can be measured, yes, but a light speed determination need not necessarily use this method.

Experiments that attempted to directly probe the one-way speed of light independent of synchronization have been proposed, but none has succeeded in doing so.

Obviously not, since the very first measurement was done exactly in that manner.  Remember this is way before atomic clocks and such.

The first observer sees that the moving clocks are not the same distance from the other observer when they're zeroed.  That's why they're not synced in that frame.

Again, this is the heart of the problem. The first observer, Alice, has no way of determining that the very same is not true for her own clocks - in her own reference frame.

Nonsense.  She has a tape measure.  That's how its done.  She can't use it for Bob's clocks since they're moving, but both Alice and Bob know that Bob's clocks are not synced in Alice's frame.

I tire of this endless repeating of the same points.  Are you going to say anything new?

You're conflating two different things here, the distance from the observer to each clock and the distance from the two "moving-clock synchronization events" to the moving observer.

All frame dependent things, and all these things are meaningless without those references.  Your whole problem (which I suspect is deliberate) is trying to interpret frame dependent statements as frame independent statements. I've pointed it out in every post, yet you persist in statements like the above one, and a great deal of the others.  Few of the statements are absolute (frame independent), and there is only conflict when you incorrectly treat them as such.

You are somewhat mistaken though, bcos the moving observer, Bob, is equidistant from the clocks and therefore from the "moving-clock synchronization events".

See what I mean?  You did it again there.

I think what you mean is that the light pulse travels a shorter distance to one clock than the other.

And again.  No, I don't mean this.  You repeat the same mistake with almost every statement.  You'll do it in the next post.  You'd get a poor grade if you took the course because you won't see your mistake when it is repeatedly pointed out.

The experimental support for relativity has lead us to accept such "spooky action"

Spooky action is more of a QM thing, but until a message can be sent via such a mechanism, I see no action.  I personally stand by the principle of locality.  Others choose different principles.  You can't have them all.

My aplogies if I have caused confusion with my use of the term "localized". It might instead be more clear to talk in terms of two locations. We have the clocks "onboard the train" and the clocks "on the platform". In this sense relativity says, the clocks onboard the train are synchronised, in the frame of the train, but not from the perspective of an observer at rest on the platform.

Wow, you kept the references that time.  Very good.
Anyway, 'localized' or 'local' doesn't mean any of that.  It means sufficiently all in the same place as to not make a difference to the situation at hand.  Since we're timing light moving the length of the train, the clocks at either end are not local to each other since their separation from the observer is the thing we're measuring.  It makes a difference.

Because reltivity says that this is more than just the case that the clocks appear unsynchronised from the platform

It says they're not synced in the platform frame.  We've not made any statement about appearances.  It could appear to the platform observer that one train clock runs at twice the rate of the other.  We'd need a lot more information to determine appearances.

it says that both statementss are equally true. Therefore, the clocks onboard the train are both synchronised with each other and not-synchronised with each other, in their physical locations onboard the train.

It says none of these statements at all actually. Both statements are meaningless, hence not even wrong.

The question lacks frame references, so is largely meaningless

I have clarified that we can assume "in the frame of the 'stationary system" given the symmetry.

By point 1 above, even those words no longer identify a frame.

To rephrase: Simply ask the question: is it possible that the observer in the stationary frame is mistaken about the simultaneity of the clock synchronisation events, in the stationary frame?

No.  They are correct about it.

Given that they see a scenario where light returns simultaneously from non-synchronised clocks.

In a given frame, light can arrive at an event simultaneously from non-simultaneous sources if those sources are not equidistant from the point of measurement.
Events are frame independent, which means any observer in any frame will see these clock-sync events being observed simultaneously.

Again, we can imply "in the frame of the "stationary system".

Ambiguous, per point 1.  You mean Alice's frame?

The point being contested is that simultaneity is frame dependent.

OK.  If it isn't, there are some interesting empirical falsifications I can suggest.

An unavoiable requirement of frame dependent simultaneity is that there must be one reference frame in which events are simultaneous (otherwise there is no basis for the relativity of simultaneity).

All events?  No.  Random events X and Y?  No.  The Titanic makes contact with iceberg.  The Titanic make contact with the ocean floor.  The is no reference frame in which those two events are simultaneous.  Only with pairs of events separated in a space-like manner is there a set of reference frames in which the pair is simultaneous.

To delare that events are simultaneous in any frame simply isn't justified.

But I can demonstrate it using the methods you describe, so the declaration is totally unnecessary.

Light speed was initially measured using another reliable clock that could be moved closer and further away.  It was an inertial clock (a steadily rotating thing like Earth), not based on light at all.

An observer moving relative to the Earth cannot use the Earth.

The observer was on Earth.  There was little choice in the matter at the time.

Maybe I've misunderstood your point. We were talking about the use of clocks to measure the speed of light, in the context of the thought experiment.

You were trying to show that light clocks could not be used to measure light speed, and I agreed.  So they used a non-light clock.  I think LIGO uses a light clock of sorts, not to measure time, but to measure a difference in time.

What clock are you suggesting that Bob use to measure the speed of light, where the effect of relative motion won't result in his clock offsettiing any discrepancy in the speed of light?

Any clock will do.  You need to devise an experiment where the effect of relative motion cancels out.  So maybe in a different frame the distance is 10% shorter, but the simple clock also runs 10% slower, so the same light speed measurement is obtained.  So we know that the speed can be determined without a requirement for the test being performed in a special frame.
Yes, we assume here that light speed will be measured identically in any frame, but that has been empirically verified.

The metric system is neither fundamental nor emergent. "Time" is system of measurement like the metric system and so,

No.   The metric system is about grams and meters and such, not mass and length.  Likewise the system of time measurement is seconds and years and such, not time.  You're making an invalid comparison between a thing and the units of measuring the thing.

time attempts to express duration in commin units.

That's like saying that length attempts to express distance in common units.  No, it is the metric system that slices up distance like that, just like the arbitrary units of seconds and such is the standard Earth system that slices up time.  Time is not the units.  With that I agree.

3D space is self-evident (not to say the holographic principle isn't correct). The "dimension of time" however, is not self-evident. We only ever observe things in the present instant i.e. the "now". Therefore, we cannot - not even in principle - oberve a temporal dimension; that is, we can never observe things extended in time.

Agree, but a corollary of that is that you can't observe space either.  If you can only observe things in the present, then you only have access to input here and now.  The cup in front of me cannot be observed even in principle since it takes time for light to get to me from there.  I can only suspect it is there now due to the current image I have that shows a state in the past that no longer exists if there is no time dimension.

Both interpretations of time are valid, and relativity theory doesn't insist on one of them.  You are free to envision the universe as 3D.  Plenty do.

[the_roosh (OP)]

I'm not sure why you're having such difficulty with the idea of "the stationary system" aka "the stationary frame". In his 1905 paper, Einstein starts by talking about an observer in "the stationary system" and builds up from there.
I'm simply following the convention used by Einstein in that paper. We're starting from the ground up.

We're looking at things solely from Alice's perspective, in Alice's frame, on the platform and making deductions based on her observations.

Hopefully, this clarifies things and we can move on.

You keep retorting with "frame dependence" but that is simply using the conclusion to justify the assumption - I'm challenging the assumption, so "frame dependence" isn't a given.

================
Here's the problem!
================
I'm taking the following reply and moving it up here because it represents the point of contention entirely. I will hold off on replying to some of the other points, because resolving this resolves them. The opening paragraphs actually address the bulk of the objjections raised as well.

The first observer sees that the moving clocks are not the same distance from the other observer when they're zeroed.  That's why they're not synced in that frame.

Again, this is the heart of the problem. The first observer, Alice, has no way of determining that the very same is not true for her own clocks - in her own reference frame.

Nonsense.  She has a tape measure.  That's how its done.  She can't use it for Bob's clocks since they're moving, but both Alice and Bob know that Bob's clocks are not synced in Alice's frame.

I tire of this endless repeating of the same points.  Are you going to say anything new?

I have to keep repeating them bcos they clearly haven't been understood. And your reply to this point shows precisely where your misunderstanding lies.

=========
Conflation
=========

Here is the issue, here is the assumption I have been trying to demonstrate. You are conflating the distance that Alice measures, [with her measuring tape] from the emitter to each clock, in her frame of reference, with the distance that the light pulses travel from the emitter to each clock, in her frame of reference. Herein lies the assumption.

Remember that [from her reference frame] Alice sees Bob measure the distance from his emitter to each of his clocks, on the train, with his measuring tape. She sees that he measures the distance from emitter to each clock as being equidistant on the train, with his measuring tape.

It doesn't matter that length is frame dependent, it only matters that she sees Bob measure the same distance to each clock on the train, with his measuring tape.

What she then sees is the light pulse from Bob's emitter, travel a shorter distance to the clock at the rear of the train - because that clock is moving towards the light pulse - and travel a longer distance to the clock at the front of the train - because that clock is moving away from the light pulse. She sees all of this from her vantage point, in her frame on the platform.

The opposite is true for each light pulse on the return leg, so the effects cancel out and the light pulses return simultaneously to Bob. This is what Alice observes of Bob's synchronisation procedure, from her reference frame, on the platform.

So, [from her frame] Alice observed Bob measure the distance to each clock (with his measuring tape, on the train). She saw [from her frame] that he measured them to be equidistant (with his measuring tape, on the train). She saw the photons in Bob's set-up, on the train, travel distances not equal to the distances measured from clock to emitter.

=============================
Applying her observations to herself
==============================

Alice, being capable of logical reasoning, deduces that the distance measured from emitter to clock, does not necessarily equal the distance travelled by the light pulses to each clock, in her frame also.

She wonders if the same thing has happened to her, as she observed happen to Bob.

Indeed, Bob sends his........take a deep breath, you know what's coming....bodycam footage confirming that the same thing has happened in her clock set up.

=========
Conclusion
=========

So, to reiterate: the assumption that is made in Einsteinian relativity, is that the distance that the light pulses in Alice's synchronisation set-up, in her frame of reference, on the platform, is the same as the distance she measures from emitter to clock. Her observtions of Bob should show her that this is not a justified assumption. Indeed, the.......here it comes again....bodycam footage from the infinite number of relatively moving observers showing her that her clocks are not synchronised, shoulld be enough to persuade her, that she was mistaken in her assumption.

To clarify, her assumption was that the distance measured from emitter to clock is the same distance that the photon travels; this in turn leads to the assumption of simultneity of clock synchronisation events, which is the assumption that her clocks are synchronied.......in her frame, on the platform.

It is this assumption which leads to the conclusion of reativitiy of simultneity aka frame dependent simultneity, and it is this set of assumptions which are unjustified.

Can we drop the whole bodycam thing then?  The purpose of that seemed to be to prove a case to the other observer over some point about which they disagreed, but they agree on all points.  There is no conflict as you say.

They do not agree on all points!
"Two observers in relative motion disagree on the timing of the two events and on the associated synchrony of the clocks."
(pitt.edu/~jdnorton/teaching/HPS_0410/chapters/Special_relativity_rel_sim/index.html).
There is no contradiction because Einsteinian relativity allows observers to disagree with each other.

The bodycam will be retained to demonstrate the choice between observational evidence and simple assumption.

[Halc]

I'm not sure why you're having such difficulty with the idea of "the stationary system" aka "the stationary frame". In his 1905 paper, Einstein starts by talking about an observer in "the stationary system" and builds up from there.

He clearly designates one arbitrary frame as such for notational convenience. I notice you didn't include that part of the quote despite its importance.
In post 6 (point 1) you redefined the words to mean one's own frame, which makes the term ambiguous in absence of identification of whose frame we're talking about.  I like that much better since it emphasizes the symmetry.
Anyway, I framed all my replies for post 6 with this new definition of 'the stationary frame' which you give in the first point of that post.

I'm simply following the convention used by Einstein in that paper.

Then your point 1 contradicted that convention.  Why can't we say Alices's frame instead?  Alice is designated the stationary one if we're to go by Einstein's convention. The first observer is arbitrarily designated the stationary one.

We're looking at things solely from Alice's perspective, in Alice's frame, on the platform and making deductions based on her observations.

Then don't quote statements made about different frames.

You keep retorting with "frame dependence" but that is simply using the conclusion to justify the assumption - I'm challenging the assumption, so "frame dependence" isn't a given.

OK.

=========
Conflation
=========

Here is the issue, here is the assumption I have been trying to demonstrate. You are conflating the distance that Alice measures, [with her measuring tape] from the emitter to each clock, in her frame of reference, with the distance that the light pulses travel from the emitter to each clock, in her frame of reference.

Yes, I do.

Herein lies the assumption.

Why is it a bad assumption to make?  All clocks, observer, tape measures, etc are all stationary in this frame and remain so for the duration between the relevant events.

Remember that [from her reference frame] Alice sees Bob measure the distance from his emitter to each of his clocks, on the train, with his measuring tape.

Bob is moving, so she doesn't see this happen in her reference frame.  He's measuring things that are not standing still in Alice's frame, so his measurements are invalid in that frame.  How can Bob know where the clocks will be (in Alice's frame) when they emit their sync pulse?  They haven't gone off yet, or they did a while ago, and either way, they're not at that spot when he takes his distance measurement.
It's like trying to locate the midpoint of a moving car by making a mark at the front and back on the road and then after finding the midpoint on the road between those marks, making a mark on the car above it, which probably isn't even above it at all anymore.  But that would be a valid way to do it if such procedures were frame independent.  The fact that it doesn't work means the assumption of frame dependence is a valid assumption.

She sees that he measures the distance from emitter to each clock as being equidistant on the train, with his measuring tape.

She sees no such thing.  Bob is using completely invalid methods for making that measurement in Alice's frame, like trying to measure the height of a hyperactive child that won't stop jumping up and down.

What she then sees is the light pulse from Bob's emitter, travel a shorter distance to the clock at the rear of the train - because that clock is moving towards the light pulse - and travel a longer distance to the clock at the front of the train - because that clock is moving away from the light pulse. She sees all of this from her vantage point, in her frame on the platform.

I agree that the one pulse goes the longer distance in that frame, and thus takes longer to get between the clocks than does the other pulse.  This is easily worked out from the premise of constant light speed.  The gif Janus showed you (does he make those?) makes that pretty clear.

The opposite is true for each light pulse on the return leg, so the effects cancel out and the light pulses return simultaneously to Bob.

I think you mean that light going from Bob to the front and back to Bob travels the same net distance as the one going from Bob to rear and back.  Yes, that's obviously true since the departure and arrival of both signals is simultaneous (one event 1 and 3).  But since in Alice's frame the one going forward takes so much longer on the first leg, the rear mirror reflection event (that starts the clock there) obviously occurs first in that frame, so the clocks are very obviously not in frame as far as Alice is concerned.  This is exactly what she expected and Bob agrees with that assessment.

[the_roosh (OP)]

He clearly designates one arbitrary frame as such for notational convenience. I notice you didn't include that part of the quote despite its importance.
In post 6 (point 1) you redefined the words to mean one's own frame, which makes the term ambiguous in absence of identification of whose frame we're talking about.  I like that much better since it emphasizes the symmetry.
Anyway, I framed all my replies for post 6 with this new definition of 'the stationary frame' which you give in the first point of that post.

My apologies, I presumed that everyone who would be replying this would already be familiar with Einstein's paper and his use of the convention. I presumed they would recognise that I was folllowing that convention. I take your point though, it's always better to be explicit about these things.

Then your point 1 contradicted that convention.  Why can't we say Alices's frame instead?  Alice is designated the stationary one if we're to go by Einstein's convention. The first observer is arbitrarily designated the stationary one.

We're not in disagreement here. We can (and do) use Alice's frame. We could just as easily start with Bob, the symmetry of the scenario means that the reasoning applies eqally well to either. We are choosing one of them and examining things solely from their perspective.

We're looking at things solely from Alice's perspective, in Alice's frame, on the platform and making deductions based on her observations.

Then don't quote statements made about different frames.

Any statements made are based on observations made by Alice, until we introduce the bodycam footage. This is perfectly valid if you don't a priori assume the validity of the Einsteinian interpretation i.e. if you don't assume your conclusion of frame dependence. It's valid regardless, but jumping to the conclusion before the validity of the foundational assumption has been established just serves to obfuscate the issue.

Why is it a bad assumption to make?  All clocks, observer, tape measures, etc are all stationary in this frame and remain so for the duration between the relevant events.

Be careful here with your frame dependent terminology. They all remain stationary, with respect to what? Bare in mind that one cannot be stationary with respect to a set of imaginary, mathematical co-ordinates. To describe the physical scenario we should more accurtely say that Alice is at rest relative to the emitter, and both are at rest relative to the clocks. This is her synchronisation set up.

But, Alice can say the exact same thing about Bob's set up. He is at rest relative to the emitter, and both are at rest relative to the clocks. This is his synchronisation set up, as observed by Alice. Both are in motion relative to each other.

You say that "all clocks, observer, tape measures, etc are all stationary in this frame and remain so" but you are leaving out the central actor in the whole synchronisation process, the light pulses. They do not remain "stationary". So, how is the distance they travel in Alice's frame determined. She assumes that the distance traveled by the light pulse to clock A is the same as the distance traveled by the light pulse to clock B and that both these distances are the same as the distance she measured from the emitter to each clock.

She observes Bob making similar measurements on the train (from her perspective). He too assumes that the distance traveled by the light pulse to clock A is the same as the distance traveled by the light pulse to clock B and that both these distances are the same as the distance he measured from the emitter to each clock. Alice however, observes this not to be the case - she observes the photon travel a shorter distance to clock A than the one to clock B, while also observing the light pulses return simultaneously to Bob. She concludes that Bob is mistaken in his assumption about his clocks being synchronised.

Observing - what she considers to be - Bob's failed synchronisation attempt, offers an alternative explanation for her own synchronisation procedure. It is possible that, in her frame, clock A was moving towards the light pulse while clock B was moving away from it. Everything would still appear the same to her, everything would appear stationary in her frame and the light pulses would return simultaneosuly just the same. As per the Galilean Principle of Relativity, there is no experiment she can do to verify or dismiss this.

So, she is left with 2 possible explanations for her clock synchronisation procedure - both of which give would give rise to the exact same obervations, in her own frame. One in which the clocks are synchronised (in her own frame) and one where they aren't synchronised (in her own frame). How does she decide between the two?

This is where the bodycam footage comes in. Bob's observation represent empirical evidence that her clocks are not synchronised. We can add in an infinite number of such observations from an infinite number of relatively moving observers, such that all empirical evidence points to the fact that her clocks are not synchronised versus her lone assumption that they are. That is why it is a bad assumption.

Remember that [from her reference frame] Alice sees Bob measure the distance from his emitter to each of his clocks, on the train, with his measuring tape.

Bob is moving, so she doesn't see this happen in her reference frame.  He's measuring things that are not standing still in Alice's frame, so his measurements are invalid in that frame.  How can Bob know where the clocks will be (in Alice's frame) when they emit their sync pulse?  They haven't gone off yet, or they did a while ago, and either way, they're not at that spot when he takes his distance measurement.

Be careful with your use of the term "moving" here because your confusing two different things. At this point in the discussion, we're not talking about Bob's observations of Alice, we're talking about Bob setting up his synchronisation procedure, on the train.

Bob's set-up is symmetrical to Alice's. He is at rest relative to his emitter and his clocks, and he and the emitter are equidistant from both clocks. This is the observation Alice makes of Bob's set-up. It is precisely this symmetry between the two set-up that means that what Alice observes happen in Bob's synchronisation set-up offers her an alternative explanation of what happens in her own (in her frame).

She sees that he measures the distance from emitter to each clock as being equidistant on the train, with his measuring tape.

She sees no such thing.  Bob is using completely invalid methods for making that measurement in Alice's frame, like trying to measure the height of a hyperactive child that won't stop jumping up and down.

You do realise that this is contradictory to what Einsteinian relativity actually says, right? The whole point is that Bob's measurements of Alice's experiments are just as valid as Alice's measurements of her own experiments. This where the Relativity of Simultaneity comes from. Bob measures events to be non-simultaneous in Alice's frame (that she assumes are simultaneous in her frame).

I agree that the one pulse goes the longer distance in that frame, and thus takes longer to get between the clocks than does the other pulse.  This is easily worked out from the premise of constant light speed.  The gif Janus showed you (does he make those?) makes that pretty clear.

Alice makes the above observation of Bob's light pulses. She assumes that the same is not true for her because she employs the Einsteinian convention that the time from A to B equals the time from B to A. Her observations of Bob's synchronisation procedure offer an alternative explanation for her own, which would result in the exact same observations being made. Add to this Bob's empirical observation [of Alice's synchronisation procedure] and Alice is left with her assumption that the clocks are synchronised versus the observtional evidence that they are not.

I think you mean that light going from Bob to the front and back to Bob travels the same net distance as the one going from Bob to rear and back.  Yes, that's obviously true since the departure and arrival of both signals is simultaneous (one event 1 and 3).  But since in Alice's frame the one going forward takes so much longer on the first leg, the rear mirror reflection event (that starts the clock there) obviously occurs first in that frame, so the clocks are very obviously not in frame as far as Alice is concerned.  This is exactly what she expected and Bob agrees with that assessment.

Agreed. The point being that Alice has no way of knowing that the same has not happened in her own synchronisation procedure. She assumes that the distance the signals travel to each clock is the same - as per the Einsteinian convention - however, it is just that, an assumption. If she was mistaken in her assumption, she would have no way off knowing bcos the signals would travel the same net distance and arrive back simultaneously.

Again, it's her assumption versus Bob's observation.

[Halc]

All clocks, observer, tape measures, etc are all stationary in this frame and remain so for the duration between the relevant events.

Be careful here with your frame dependent terminology. They all remain stationary, with respect to what?

With respect to the frame referenced.  That's what 'stationary in this frame' means.
The full context of that comment explicitly identified Alice's frame.

Bare in mind that one cannot be stationary with respect to a set of imaginary, mathematical co-ordinates.

The frame is not imaginary (except it is since this is a thought experiment).  The frame was defined using real references, in this case Alice or either of her clocks.  One doesn't even need a stationary object to define a frame.

To describe the physical scenario we should more accurtely say that Alice is at rest relative to the emitter, and both are at rest relative to the clocks. This is her synchronisation set up.

That was all described in the OP, yes, except we hadn't named that observer Alice at that point.

But, Alice can say the exact same thing about Bob's set up. He is at rest relative to the emitter, and both are at rest relative to the clocks. This is his synchronisation set up, as observed by Alice. Both are in motion relative to each other.

You say that "all clocks, observer, tape measures, etc are all stationary in this frame and remain so

All of Alice's components are stationary in her frame.  Bob and his clocks and tape measure are obviously not stationary in Alice's frame.

" but you are leaving out the central actor in the whole synchronisation process, the light pulses. They do not remain "stationary". So, how is the distance they travel in Alice's frame determined. She assumes that the distance traveled by the light pulse to clock A is the same as the distance traveled by the light pulse to clock B and that both these distances are the same as the distance she measured from the emitter to each clock.

Yes, she can validly determine that since the clocks are stationary.  Neither emitter nor Alice need be stationary.  We just need to know the location in space where the emit event takes place and the observation of the return (if there is one) takes place.  Since both are stationary, we know where these events take place.

Lengths (distance that the light traveled) is not an objective thing under relativity.  I think you are trying to assert that such distances are different than what the tape measure says, but that's not true under relativity.  Distances are frame dependent, and not at all defined for moving objects.  The distance between Earth and Venus is undefined since they're always moving relative to each other.  The distance between relatively stationary objects, in the frame in which they are stationary, is their objective proper distance, and that distance is by definition the distance traveled by light between them in that frame.
I know an absolute interpretation defines things otherwise and perhaps doesn't define proper distance at all, but in an absolute interpretation, Alice has not synced her clocks.  She has used an invalid procedure.

She observes Bob making similar measurements on the train (from her perspective). He too assumes that the distance traveled by the light pulse to clock A is the same as the distance traveled by the light pulse to clock B

He does not.  We're assuming everything in Alice's frame, remember?  Bob knows he and his clocks are moving in that frame and is not using a valid procedure for syncing them in that frame.  At no point is Bob mistaken about anything.  We assume he's educated.

Observing - what she considers to be - Bob's failed synchronisation attempt, offers an alternative explanation for her own synchronisation procedure. It is possible that, in her frame, clock A was moving towards the light pulse while clock B was moving away from it.

Not possible.  The clocks are nailed to the floor on which the tape measure is glued.  She's not moving across that floor.  Are you suggesting she's faking the evidence, or that somebody is moving her clocks when she blinks?

Everything would still appear the same to her, everything would appear stationary in her frame and the light pulses would return simultaneosuly just the same. As per the Galilean Principle of Relativity, there is no experiment she can do to verify or dismiss this.

Yes there is. This whole paragraph is wrong. She would see the clocks moving away or closer, tough to do when they're nailed down.  So she'd see the nails breaking or the floor ripping up.  It isn't difficult to detect motion relative to ones self.  If you doubt it, sit in the street.

Bob is moving, so she doesn't see this happen in her reference frame.  He's measuring things that are not standing still in Alice's frame, so his measurements are invalid in that frame.  How can Bob know where the clocks will be (in Alice's frame) when they emit their sync pulse?  They haven't gone off yet, or they did a while ago, and either way, they're not at that spot when he takes his distance measurement.

Be careful with your use of the term "moving" here because your confusing two different things.

I reference only Alice's frame in all that, repeatedly even.  The statements are not ambiguous.  If you think they are, I'll repeat: All that is described from Alice's frame.

At this point in the discussion, we're not talking about Bob's observations of Alice, we're talking about Bob setting up his synchronisation procedure, on the train.

I never described Bob watching Alice.  Perhaps Alice is watching Bob since you think that's important, but she already knows that Bob isn't trying to sync his clocks in her frame.

Bob's set-up is symmetrical to Alice's. He is at rest relative to his emitter and his clocks, and he and the emitter are equidistant from both clocks. This is the observation Alice makes of Bob's set-up.[/quote]
It is precisely this symmetry between the two set-up that means that what Alice observes happen in Bob's synchronisation set-up offers her an alternative explanation of what happens in her own (in her frame).[/quote]The explanation isn't alternative.  I have but one explanation so far, or two if you consider each system from the other frame, in which case nothing is synced.

Bob is using completely invalid methods for making that measurement in Alice's frame, like trying to measure the height of a hyperactive child that won't stop jumping up and down.

You do realise that this is contradictory to what Einsteinian relativity actually says, right?

No.  Bob knows very much that he's moving in Alice's frame, and (Galilean) relativity doesn't say otherwise.

The whole point is that Bob's measurements of Alice's experiments are just as valid as Alice's measurements of her own experiments.

Bob doesn't measure any of Alice's experiments.  He just watches Alice do it, and Alice does a valid measurement of her stuff in her frame.  But Bob does not do valid measurement of his own stuff in Alice's frame.  It isn't symmetrical because we're considering only Alice's frame.  You want symmetry, consider what Bob is doing in Bob's frame.

This where the Relativity of Simultaneity comes from. Bob measures events to be non-simultaneous in Alice's frame (that she assumes are simultaneous in her frame).

We're talking about Alice's events, right?  Bob hasn't measured them, having only watched Alice do it, but if he did, they would be measured simultaneous in Alice's frame. Those events are only non-simultaneous in Bob's frame. So I disagree with your statement.  You seem not to know your relativity at all.  We haven't even touched on the mathematics yet. You don't understand the base concepts at all.

Also, Alice doesn't assume anything (except that Bob is not a fool).  Her experiment demonstrates that her clocks are in sync in her frame.  She knows it, and Bob knows it because he watched her do it.

Alice makes the above observation of Bob's light pulses. She assumes that the same is not true for her because she employs the Einsteinian convention that the time from A to B equals the time from B to A.

In Alice's frame, there is not A to B and B to A.  If light is emitted at point A, B is a mirror, then there is nothing at A when the light gets back because Bob there has moved elsewhere.  How can you not see that?

Her observations of Bob's synchronisation procedure offer an alternative explanation for her own

No they don't.  She's not moving in her frame.  Bob is very much moving in her frame.

The point being that Alice has no way of knowing that the same has not happened in her own synchronisation procedure.

You keep insisting on this, but it is wrong.  She has every way of knowing, which is why nobody disagrees on anything.  Everybody is doing precise measurements and nobody is guessing about anything.  There is no alternative explanation about anything since there is no conflicting assessment of what happened.  Everybody is right.

She assumes that the distance the signals travel to each clock is the same - as per the Einsteinian convention

Einstein says that distance is frame dependent.  Nobody assumes anything.  I tire of saying that.  Relativity isn't about anybody assuming anything. Go to an absolute interpretation if you want assumptions being necessary.

- however, it is just that, an assumption.
 If she was mistaken in her assumption, she would have no way off knowing bcos the signals would travel the same net distance and arrive back simultaneously.

Not sure which clocks you're talking about.  No asumptions either way.  Her own clocks are not moving in her frame, so she knows (not assumes) the distance to them is the distance that light travels to get to them in her frame.
She also knows (not assumes) that since Bob's clocks are moving along with Bob in her frame, that light will take longer to reach the receding clock and that one will subsequently be behind in her frame.  Again, no assumptions.  She has every way of knowing all necessary facts for these assessments, despite your denial of it above.
Alice is educated remember, and knows how to wield a tape measure.

[the_roosh (OP)]

All of Alice's components are stationary in her frame.  Bob and his clocks and tape measure are obviously not stationary in Alice's frame.

OK, let's try to break things right down. Let's take a common formulation of the thought experiment. Let's say Alice and Bob are in spaceships.

All components are stationary, in her frame. Let's clear all components out of the spaceship, including Alice, so we are left with just the spaceship. Is the spaceship stationary?

[Colin2B]

Let's clear all components out of the spaceship, including Alice, so we are left with just the spaceship. Is the spaceship stationary?

Relative to what?
It certainly is relative to the spaceship! However, Bob might disagree.
You can also set up a frame which moves with the spaceship and the spaceship is at rest relative to that.

You seem to have problems with the different viewpoints here, but there is no surprise that Alice and Bob see different things and that these differences are symmetrical, but this does not affect whether they can say their own clocks in their own frames are synchronised. The same sort differences of viewpoint occur in Galilean relativity. Also, if you follow through the differences of measurements performed in their respective coordinates (coordinate transforms) you will see that these differences are to be expected and easily understood.
It makes no difference that Alice is intelligent and can work out what’s happening, she takes measurements from her frame.
In Galilean relativity we can see that Bob on a railway carriage sees a ball bouncing up and down, in order to shoot it down his gun need only track up and down, Alice however sees the ball following a sine wave, a very different prediction.
We are also used to everyday experiences of frame dependant views, we all know that the passenger in a car following a curve continues in a straight line, but that doesn’t make the centrifugal force any less real to the passenger.
I would recommend you look at the coordinate transforms for Alice’s viewpoint in order to understand this situation as you are getting lost in misunderstanding what the bodycam footage really shows - the view from one frame only, which is not relevant to what the other frame views.
Alice doesn’t need to question whether her clocks are synchronised, she’s a bright girl and can work out that they are, but that synchronisation only applies to her frame.
 

[the_roosh (OP)]

Relative to what?
It certainly is relative to the spaceship! However, Bob might disagree.

Indeed, relative to what? It's a simple question. So, again is the spaceship stationary?

Saying that it is at rest relative to itself is a meaningless tautology.

ou can also set up a frame which moves with the spaceship and the spaceship is at rest relative to that.

We don't need to add anything more, it's a simple foundational question  from which we can expand. So, is the spaceship at rest - you can add any qualifiers you wish.

ou seem to have problems with the different viewpoints here, but there is no surprise that Alice and Bob see different things and that these differences are symmetrical, but this does not affect whether they can say their own clocks in their own frames are synchronised. The same sort differences of viewpoint occur in Galilean relativity. Also, if you follow through the differences of measurements performed in their respective coordinates (coordinate transforms) you will see that these differences are to be expected and easily understood.
It makes no difference that Alice is intelligent and can work out what’s happening, she takes measurements from her frame.
In Galilean relativity we can see that Bob on a railway carriage sees a ball bouncing up and down, in order to shoot it down his gun need only track up and down, Alice however sees the ball following a sine wave, a very different prediction.
We are also used to everyday experiences of frame dependant views, we all know that the passenger in a car following a curve continues in a straight line, but that doesn’t make the centrifugal force any less real to the passenger.
I would recommend you look at the coordinate transforms for Alice’s viewpoint in order to understand this situation as you are getting lost in misunderstanding what the bodycam footage really shows - the view from one frame only, which is not relevant to what the other frame views.
Alice doesn’t need to question whether her clocks are synchronised, she’s a bright girl and can work out that they are, but that synchronisation only applies to her frame.

I'm familiar with what the Einsteinian interpretation says and with the fact that it is internally consistent. I'm proposing an alternative interpretation.

Are you familiar with the empirically equivalent Lorentz-Poincare interpretation,  which is based on absolute simultaneity?

[Colin2B]

it's a simple foundational question  from which we can expand. So, is the spaceship at rest - you can add any qualifiers you wish.

The simple answer is that we don’t know.
The qualifier is that we don’t care, because it is at rest relative to it’s own reference frame and that’s all we need to know.

Are you familiar with the empirically equivalent Lorentz-Poincare interpretation,  which is based on absolute simultaneity?

Yes I am. Again, we don’t care, because we have all we need to work out the relative viewpoints and measurements.

[the_roosh (OP)]

The simple answer is that we don’t know.

Precisely! Which is why it can't be assumed that the distance the light pulses travel is equal to the distance from emitter to clock. The clocks in Alice's reference frame could be moving relative to the light pulses - well, we know they are - they could be moving in such a way that one clock moves towards the light pulse, while the other is moving away. Alice has no way of knowing which situation is the true situation - as per the Galilean Principle of Relativity.

The point is that she assumes that the distance each photon travels to each clock is the same, ss as this is what Einstein prescribes in his clock synchronization convention, in his1905 paper.

Bob's bodycam footage provides observational evidence to the contrary.

The qualifier is that we don’t care, because it is at rest relative to it’s own reference frame and that’s all we need to know.

Objects in the physical world can only be in motion or at rest relative to other physical objects. We have 2 spaceships, where are you getting this 3rd physical entity, which you are calling the spaceships "own rest frame", relative to which you are saying it is at rest?

That is a rhetorical question btw, I know you are committing the fallacy of reification with respect to the mathematical co-ordinates and saying that the spaceship is at rest relative to them; or you are populating the universe with clocks at rest relative to the spaceship and referring to those. In the latter case, we said not to introduce anything more and just talk about the spaceship.

Yes I am. Again, we don’t care, because we have all we need to work out the relative viewpoints and measurements.

Interesting that "we" don't care. Both interpretations make different ontological claims about the underlying physical structure of the universe. You might think that this would be of concern to a field of research that concerns itself with the nature and functioning of the physical world.

That is beside the point tho. The point is that there is an alternative interpretation of Relativity which doesn't involve the Relativity of Simultaneity.  This just further demonstrates the point that the Einsteinian interpretation makes the assumption of Simultaneity in "the stationary system"

[the_roosh (OP)]

I'm probably making things a bit difficult for myself here, so to try and simplify:

Einstein's clock synchronization convention unequivocally states that the synchrony of clocks must be assumed. This is done by establishing - as a matter of definition - that the time for light to travel from A to B equals the  time from B to A.

This applies in the Set-up with Alice and Bob where the time from emitter to A is established by definition to be equal to the time from emitter to B.

Bob's observational evidence demonstrates that Alice's assumption is incorrect.

To try and refer to frame dependence - to disqualify Bob's observational evidence of Alice's synchronization procedure - is simply to assume the conclusion of frame dependence.

The primary assumption is rendered unjustified by Bob's observational evidence,  hence the conclusion of frame dependence cannot be arrived at, without assuming the conclusion i.e. without circular reasoning.

[Halc]

All of Alice's components are stationary in her frame.  Bob and his clocks and tape measure are obviously not stationary in Alice's frame.

OK, let's try to break things right down. Let's take a common formulation of the thought experiment. Let's say Alice and Bob are in spaceships.

All components are stationary, in her frame.

Bob's ship and his components are not, unless the scenario has changed.  The fact that they're in ships makes no difference.

Let's clear all components out of the spaceship, including Alice, so we are left with just the spaceship. Is the spaceship stationary?

It is stationary in the ship's frame, by definition.  Sans that frame reference, the question has no meaning under the relativistic interpretation.

I see Colin2B ask "relative to what?".  He also notes the lack of reference in that question.

It certainly is [stationary] relative to the spaceship! However, Bob might disagree.

To clarify, Bob might says the ship is not stationary relative to his ship, but he does not disagree that Alice's ship (without Alice even) is stationary relative to itself, and yes, saying this is a meaningless tautology, as is "the ship is at rest in the frame in which it is stationary".
I only have to harp on that meaningless tautology because you (roosh, not Colin) seem to deny it.

So, is the spaceship at rest?

The simple answer is that we don’t know.

Precisely!

Colin is open to the question having meaning without a reference, such as "what is the distance to my elbow?".  I'm being precise in saying the question has no meaning, and is thus not a thing we don't know, but rather a thing whose answer is not even wrong.
Under an absolute interpretation, the question very much has meaning, at which point one can answer "I don't know" or possibly assume a value.

Alice has no way of knowing which situation is the true situation - as per the Galilean Principle of Relativity.

She very much knows this, per that principle.  The principle says there is no true situation.  Only the absolute interpretation denies the principle, giving meaning to the question and allowing an answer, even if it is still "I don't know".  But Alice knows because she's a relativist.

Objects in the physical world can only be in motion or at rest relative to other physical objects.

Which is why motion is undefined in a universe with a sole existant.  In an absolute universe, motion is defined but unknown even with multiple existants.

I am quite capable of describing a physical frame with no known object stationary in it (such as the frame were Earth is currently southbound at 50 million m/s).  There is always an object effectively stationary in any given inertial frame, so I cannot really assert that there is a frame with no object stationary in it.  In principle, this is allowed to exist.
The frame typically used by Lorentz-Poincare interpretation is such a frame.  If objects can only be in motion or at rest relative to other physical objects, then that interpretation is likely wrong since speeds are related to a pure mathematical frame with no known object to anchor it.
For that matter, no object is stationary simply because I can think of no object that isn't accelerating.  None of them (except in thought experiments) define an inertial frame.  Inertial frames are thus necessarily abstract.

I know you are committing the fallacy of reification with respect to the mathematical co-ordinates and saying that the spaceship is at rest relative to them;

Nobody claims a reference frame is a physical object.  It not being physical does not make it a valid reference.  It just needs definition.
If reification is a fallacy, then Lorentz-Poincare interpretation is completely fallacious since as I pointed out above, it lacks anything physical to anchor its abstract frame.  They apparently know this and thus are force to posit an invisible non-interacting entity there (something that makes no empirical difference, unlike say dark matter or dark energy).  All motion is relative to that entity, which is not in any way distinct the completely abstract mathematical one.

Back on course:  I say a reference frame, while not being a physical thing, can be completely identified given any object anywhere.  It doesn't require the object to be stationary in it to make it a valid frame.  It just needs a real reference.

Interesting that "we" don't care. Both interpretations make different ontological claims about the underlying physical structure of the universe. You might think that this would be of concern to a field of research that concerns itself with the nature and functioning of the physical world.

Yes, the interpretations do indeed make different ontological claims.  We don't care because it makes no empirical distinction.  Research is for empirical differences.  The different interpretations is just philosophy.  The relativistic interpretation is consistent with itself, and I'm only defending that stance against your misrepresentation of it.  I'm not claiming another interpretation is wrong, especially if it makes no different empirical predictions.

That is beside the point tho. The point is that there is an alternative interpretation of Relativity which doesn't involve the Relativity of Simultaneity.

Agree, there is. I'm well aware of it.

[Halc]

I'm probably making things a bit difficult for myself here, so to try and simplify:

Einstein's clock synchronization convention unequivocally states that the synchrony of clocks must be assumed. This is done by establishing - as a matter of definition - that the time for light to travel from A to B equals the  time from B to A.

This whole post is obfuscated by a lack of definition of what A and B are, per Einstein's quote.  That's what definition is being referenced (not made) in that quote.  The quote is being taken completely out of context.

This applies in the Set-up with Alice and Bob where the time from emitter to A is established by definition to be equal to the time from emitter to B.

Einstein talked about A to B equaling B to A, not E to A equaling E to B.  So this statement has zero to do with your chosen Einstein quote.

Bob's observational evidence demonstrates that Alice's assumption is incorrect.

Bob fully agrees with Alice's deductions.  You repeat this assertion over and over.  It is wrong.  It is mostly wrong because you misrepresent what Alice has demonstrated.

To try and refer to frame dependence - to disqualify Bob's observational evidence of Alice's synchronization procedure - is simply to assume the conclusion of frame dependence.

We tried to assume frame independence, and it ran into contradictions.  So again, the conclusion is deduced, not assumed.  Bob's observational evidence is never disqualified.  Both are in agreement, so disqualification is not necessary.  If you think Bob concludes something else, be explicit about where there is disagreement, because I assert there is none.

I've stated these replies before, and you continue to just assert the same statements again rather than say why my responses are wrong.