Do AEST (Absolute Euclidean Spacetime) models work?

[PeroK]

Well I've attached a picture. It did seem pretty clear.
And I've also attached a figure showing multiple objects, two of which have negative proper times. Montanus writes: "If one likes, the reversed proper-time can be conceived as if the hands of the 'internal clock' of particle G are rotating counterclockwise. According to the AEST theory a backwards running proper-time means that the particle behaves in an opposite way. Alternatively, if particle B and particle G have opposite properties, then particle G can be regarded as an antiparticle."

And regarding the diagram he also states: "The parameter axis ct is drawn perpendicular to the x₁, x₄ -plane. After a simultaneous start in the origin, the simultaneous positions of the objects constitute a circle, whose radius increases as much as the time parameter. The result is a cone in a tree dimensional diagram."

It's bad enough discussing these ideas, but discussing them with someone who doesn't even understand them, but simply has a philosophical ax to grind with modern physics seems like a total waste of time.

 

[name123]

It's bad enough discussing these ideas, but discussing them with someone who doesn't even understand them, but simply has a philosophical ax to grind with modern physics seems like a total waste of time.

Were you of the mind that the length of the lines wouldn't be the same, or that them being the same doesn't indicate that those events would be simultaneous in the absolute spacetime of AEST? Or was it perhaps me using the phrase "simultaneous in absolute time"?

 

[robphy]

Can one draw
light signals or
a light cone
or a light clock
in a space-propertime diagram?

If not, then your diagram is missing significant elements of a position vs time graph, and thus does not provide a complete map of spacetime (as a Minkowski diagram does).

 

[PeterDonis]

there is (as I understand it) a preferred frame of reference where all things move through absolute spacetime at the speed of light

The object referred to here is not a valid frame of reference, since it does not uniquely map events to coordinates.

Also, the statement that all things move through absolute spacetime at the speed of light does not, ironically, work for light itself. This viewpoint completely ignores the fundamental difference between timelike and lightlike objects and tries to treat them the same. That doesn't work.

@name123, do you want a simple answer to the title question of this thread? The simple answer is no.

If you want more than that, then I think @PeroK's comment in post #38 is highly apposite: you need to first understand the viewpoint you are asking about. Then you will understand why it does not work.

 

[PeterDonis]

The postulate is that in the absence of gravitation all objects move with a four-dimensional Euclidean velocity equal to the speed of light in a vacuum.

You can of course play around with the math to define a "four-dimensional Euclidean velocity" that works this way. But you have to do it differently for timelike and lightlike objects.

For timelike objects, just write (I'll use units in which $c = 1$ to avoid cluttering up the math):

$$
d \tau^2 = dt^2 - dx^2
$$

And then divide through by $d \tau^2$ and take the square root:

$$
1 = \sqrt{ \left( \frac{dt}{d\tau} \right)^2 - \left( \frac{dx}{d\tau} \right)^2 }
$$

The $1$ on the left is the "four-dimensional Euclidean velocity" (which would be $c$ in conventional units).

But of course you can't do this for light, because $d\tau^2 = 0$ for light and you can't divide by zero. So you have to do some different mathematical trick to define a different "four-dimensional Euclidean velocity" for light. The most common such trick is to simply define the ordinary 3-velocity of light in any inertial frame (which frame doesn't matter since it's the same in all) as the "four-dimensional Euclidean velocity".

I again will attach the three diagrams, and mention that A and E can be considered photons.

The diagrams, as far as I can tell, are just showing the math referred to above in different ways.

For the AEST not to work, there would presumably have to be a result that TR can provide that it either doesn't agree with, or cannot provide. Would you agree?

No. As far as I can tell, AEST is just rewriting the math of standard SR, so it can't possibly make different predictions from standard SR. But that also means it can't possibly justify different physical claims from standard SR. But it makes different physical claims from standard SR (and also claims to include gravitation, which standard SR does not). That is the part that doesn't work.

 

[Dale]

And I've also attached a figure showing multiple objects, two of which have negative proper times. Montanus writes: …

Which source is this? You are persistently citing unacceptable sources. Continuing to try to sneak them in will close this thread. I have temporarily deleted all of your recent posts with these unidentified references until you can clarify this. Once you have clarified the sources then I can undelete the posts

 

[name123]

Which source is this? You are persistently citing unacceptable sources. Continuing to try to sneak them in will close this thread. I have temporarily deleted all of your recent posts with these unidentified references until you can clarify this. Once you have clarified the sources then I can undelete the posts

So regardless of whether a person writes papers for journals which you count as acceptable, and thus is a presumably trusted author, you seem to be saying that nothing they have written other than what was in the papers in those journals can be quoted. So no quoting from books, or letters or anything like that, even if the author has written papers for journals. Have I understood you correctly?

The author I was quoting, has written the following papers on this topic, in the following journals that are listed in Clarivate Master

https://www.researchgate.net/profile/J_Montanus/publications (Physics Essays, vol 4, nr 3, 1991)
https://www.researchgate.net/profile/J_Montanus/publications (Physics Essays, vol 5, nr 4, 1992)
https://www.researchgate.net/profile/J_Montanus/publications (Physics Essays, vol 6 nr 4, 1993)
https://www.researchgate.net/publication/243586166_General_Relativity_in_an_Absolute_Euclidean_Space-Time (Physics Essays, vol 8, nr 4, 1995)
https://www.researchgate.net/profile/J_Montanus/publications (Physics Essays, vol 10, nr 1, 1997)
https://www.researchgate.net/profile/J_Montanus/publications (Physics Essays, vol 10 nr 4, 1997)
https://www.researchgate.net/profile/J_Montanus/publications (Physics Essays, vol 11, nr 2, 1998)
https://www.researchgate.net/profile/J_Montanus/publications (Physics Essays, vol 11, nr 3, 1998)
https://www.researchgate.net/profile/J_Montanus/publications (Physics Essays, vol 11 nr 4, 1998)
https://www.researchgate.net/profile/J_Montanus/publications (Physics Essays, vol 12 nr 2, 1999)
Proper-Time Formulation of Relativistic Dynamics (Found. Phys. 31, Issue 9, Sep 2001, Pages 1357 - 1400)
Flat Space Gravitation (Found. Phys. 35, Issue 9, Sep 2005, Pages 1543 - 1562)

It isn't the only topic he writes on.

I had assumed the rationale behind having certain restrictions on articles was to weed out work from authors that hasn't been suitably peer reviewed. But in his case, as I think is obviously clear, what he is writing on the topic has been peer reviewed in journals this site counts as reputable.

And I am assuming that by mentioning trying to sneak them in, you are saying that even if I paraphrase what he wrote on the topic in an openly free article, or drew the same diagrams myself, that wouldn't be acceptable to you and you would use that as a justification for closing the thread. Have I understood you correctly?

 

[name123]

No. As far as I can tell, AEST is just rewriting the math of standard SR, so it can't possibly make different predictions from standard SR. But that also means it can't possibly justify different physical claims from standard SR. But it makes different physical claims from standard SR (and also claims to include gravitation, which standard SR does not). That is the part that doesn't work.

It isn't just re-writing the math of standard SR because as you can see from the list of papers above one is called "General relativity in an absolute Euclidean space-time". And it uses flat Euclidean geometry even in situations with gravitation, and has the concept of absolute time.

I can't currently say much more because I what I have read about it came from sources that weren't accepted journals and Dale seems to be threatening to close the thread if I mention what they stated, even though he seems to accept the author of one paper I was using (which had I thought useful diagrams) has written on the topic for suitable journals.

 

[martinbn]

Why don't you try philosophy forums.

 

[name123]

Why don't you try philosophy forums.

Because it is a question about physics. And the person I was quoting was a physicist that has at least 12 papers on the topic published in physics journals that are on Clarivate. What I am surprised at is that the other physicists on here seem to dismiss such work almost out of hand. What I don't understand is how you think he managed to get 12 papers on the topic published in such journals over a 14 year period. The impression I get is that if he came on here, there are many that think they could easily explain to him how silly what he was stating is. But I think the easier thing for me to do is just buy one of his papers and then quote from that, as I assume Dale is just trying to maintain standards on the site, and while I might differ with him in what I think is reasonable, ultimately it is his call, and I respect that.

 

[weirdoguy]

What I am surprised at is that the other physicists on here seem to dismiss such work almost out of hand.

Not true, you've been given a lot of arguments why discussed approach is dismissed. Do you even understand them?

What I don't understand is how you think he managed to get 12 papers on the topic published in such journals over a 14 year period.

It's really not that hard, besides I see mainly one journal, Physics Essays. How high is it ranked?

 

[Motore]

So regardless of whether a person writes papers for journals which you count as acceptable, and thus is a presumably trusted author, you seem to be saying that nothing they have written other than what was in the papers in those journals can be quoted. So no quoting from books, or letters or anything like that, even if the author has written papers for journals. Have I understood you correctly?

Yes. Authors can write good papers in reputable journals on some topics and bad papers on different topics. The latter is of course not acceptable, why is that strange?

 

[name123]

Yes. Authors can write good papers in reputable journals on some topics and bad papers on different topics. The latter is of course not acceptable, why is that strange?

That isn't strange. But neither is that particularly relevant. The issue here is that the author in question wrote 12 papers on a certain topic in reputable journals that appeared on Clarivate. I was quoting from a paper on the *same* topic, by the same author, that appeared in a journal that wasn't on Clarivate, but which had an editorial staff of 21 people from reputable institutions from numerous countries. But the latter is freely available. And I was hoping that given that he is a reputable source, I would have been allowed to have quoted from it even if it had appeared on http://www.arxiv.org/ (and wasn't peer reviewed), due to him having published 12 papers on that topic in reputable journals.

 

[martinbn]

Why don't you try philosophy forums.

Because it is a question about physics.

Personally I am interested more from a philosophical point of view.

 

[name123]

Not true, you've been given a lot of arguments why discussed approach is dismissed. Do you even understand them?

Would you care to mention the one you thought was most convincing?

 

[name123]

Yes, the topic is a physics theory. So I am discussing it on a physics forum to see if there was a known problem with it. If there isn't then it is of philosophical interest.

 

[martinbn]

Yes, the topic is a physics theory. So I am discussing it on a physics forum to see if there was a known problem with it. If there isn't then it is of philosophical interest.

You have already been given explanations why it (the theory) makes no sense. What more do you need?

 

[vanhees71]

You don't believe, which utter nonsense can get published even in reputable journals. Peer review is the only sensible way to try to avoid this, but it's not fail-safe. There was once an article claiming that the Lienard-Wiechert potentials known for well more than 100 years, were in fact no solutions to Maxwell's equations. I don't understand, how such a claim could be published since it's almost completely impossible that such an established result is wrong after all. A good referee should thus have looked for the error leading to the very probably wrong conclusion of the authors. So it made it to the journal, but it was of course corrected (by J. D. Jackson by the way!), what was wrong: The authors forgot that the retarded time depends on the spatial variables and in calculating the derivatives of the potentials to get the fields and check the Maxwell equations you must of course take this dependence into account, which the authors didn't. So this even happens in journals with high or at least good standards.

Now there are more and more fake journals, where you simply pay for getting published without serious peer review. You can imagine how bad this is and which kind of "work" is published there.

 

[Dale]

So regardless of whether a person writes papers for journals which you count as acceptable, and thus is a presumably trusted author, you seem to be saying that nothing they have written other than what was in the papers in those journals can be quoted.

First, direct quotes should always be specifically attributed. That is completely standard in all scholarly fields, not just here on PF.

Second, authors are not “trusted”. If that were the case then this author would not be trusted. His best work is in low-quality journals, and his opinions from what I have seen are not very well conceived. However, even authors with a track record of highly reputable publications in leading journals write in informal works like pop sci books, which are not acceptable here.

Third, you are just throwing out a bunch of references to see what will stick. You need to critically evaluate your own sources and be more discerning before posting. Being on the Clarivate MJL is a sort of bare minimum for even appearing here. But there are a lot of sources in the MJL that are not very credible.

If you are unsure of the credibility of a source, I recommend looking at Eigenfactor.org ( http://eigenfactor.org/projects/journalRank/journalsearch.php ). Just because you find a reference that is not excluded by our rules doesn't mean that others will universally consider it credible. Physics Essays, in particular, is such a low quality journal that it doesn’t even have an Eigenfactor rating. So although I won’t delete it as a moderator of the forum, but as a scientist I would consider its content with a high degree of skepticism.

The author I was quoting, has written the following papers on this topic, in the following journals that are listed in Clarivate Master

That is not what I was asking. I was asking for the specific sources of the specific quotes and figures that you were spamming.

Edit: after a discussion with the OP the thread is reopened. The deleted messages will remain deleted. The OP now understands the policy and had made an honest mistake in posting the deleted messages.

However, the thread is on a tight leash.

 

[name123]

I have now bought the paper Proper-Time Formulation of Relativistic Dynamics which appeared in a journal listed on Clarivate.

The theory does contain the postulate that: in the absence of gravitation all objects move with a four dimensional Euclidean velocity equal to the speed of light in a vacuum.

Regarding any suggestions that the Euclidean geometry bears nonsensical properties such as nonlocality and non-causality the paper accepts that has been shown with relative Euclidean spacetime. But points out that an absolute Euclidean spacetime does not bear such odd properties

Regarding comments about Proper-Time diagrams perhaps not being able to display light signals, or the amount of information shown in Minkowski diagrams, I have attached 3 figures from the article.

Fig 2. is Proper-Time diagram which also shows the parameter. By convention one object is assumed to be at rest, with its clock therefore showing absolute time. In this case it is particle C.

While some might claim there is no absolute time, there is the concept in Proper Time Physics.
Montanus writes: 'We therefore will restrict ourselves to an absolute Euclidean spacetime (AEST ). It will be clear that the adverb ‘‘absolute’’ should not be seen in the historical meaning of a spacetime where all the clocks run equally fast. Instead, with ‘‘absolute’’ is meant that there is a preferred frame of reference. A clock at rest with respect to this absolute rest frame will run fastest. Its time will be used as a time parameter.'

In this diagram it can be seen that particle A which is a photon moves through parameter time, even though it doesn't move through proper time. Thus using a diagram like Fig 1, one could show a light going out and returning.

Fig 3. is the top down version if you like of Fig 2. And doesn't show the movement through absolute time. And thus such a figure wouldn't be suitable for showing light rebounding as it would all be along the same x axis. It is also worth noting that where particle D appears to have a negative proper time, according to the AEST theory a backwards running proper time of a particle is interpreted as the reversal of intrinsic properties such as charge and spin.

Fig 4. Is a front view of Fig 2, and does show movement through parameter time, and so would be suitable for showing a light beam going out and being reflected back. Montanus comments:
"The projection of the full diagram in Fig. 2 to the diagram in Fig. 4 illuminates why there is a light cone in the Minkowski diagram and a gap outside the light cone. It also illuminates that the trajectories of the objects moving in the AEST at an angle φ and −φ are mapped on the same trajectory in the Minkowski diagram. The present approach makes clear that the Minkowski diagram actually is a space diagram extended with a parameter axis. If one regards (erroneously) the time parameter as the simultaneous fourth coordinate for all the objects, the diagram in Fig. 4 then will be mistaken as a space-time diagram."

I hadn't fully appreciated Dale's comments about the proper spacetime coordinates not being properly defined. And can see now that the approach does not allow one to determine which events are simultaneous in absolute time. Although the lengths in a diagram such as Fig 3 being equal would be necessary, it would not be sufficient. It would require the diagram rotation to be correct, such that the object that by convention was assumed to be at rest with absolute spacetime, was actually at rest with absolute space time for the other coordinates to be correct.

Apologies there for being so slow to understand.

What I am still interested in is whether it does allow the modelling of situations even where gravity is present, using absolute flat Euclidean space time.

 

[Dale]

an absolute Euclidean spacetime does not bear such odd properties … By convention one object is assumed to be at rest

Note that these two statements are incompatible with each other. You cannot have an absolute spacetime and then allow objects to be assumed to be at rest by convention. An absolute spacetime means that being at rest is not a matter of convention. This is further strengthened by the author’s own description of the meaning they attribute to the term.

 

[name123]

Note that these two statements are incompatible with each other. You cannot have an absolute spacetime and then allow objects to be assumed to be at rest by convention. An absolute spacetime means that being at rest is not a matter of convention.

The odd properties comment that was one of the statements was regards to nonlocality and non-causality.

Yes an absolute spacetime means that actually being at rest would not being a matter of convention. But without any experimental way of determining whether an object is at rest in relation to absolute spacetime, those using the model by convention just assume one to be to get the results. To achieve the same results as you would using TR. I don't see any incompatibility there. You could with normal TR hold the view that there did actually exist a preferred frame of reference.

 

[PeterDonis]

It isn't just re-writing the math of standard SR because as you can see from the list of papers above one is called "General relativity in an absolute Euclidean space-time".

The full theory might include some rewriting of the math of standard GR. I don't have access to the paywalled papers so I can only go by what you are posting in this thread and the abstracts I can read. My opinion based on those is that it is re-writing standard math plus physical claims that are just the author's unsupported opinion and cannot be justified by the math.

The author I was quoting, has written the following papers

Most of these links just go to the author's profile on researchgate (which, btw, is one of those sites that is notorious for posting low quality papers).

 

[robphy]

Yes, the topic is a physics theory. So I am discussing it on a physics forum to see if there was a known problem with it. If there isn't then it is of philosophical interest.

I have now bought the paper Proper-Time Formulation of Relativistic Dynamics which appeared in a journal listed on Clarivate.

From a google search of similarly titled papers by the author, some troubling phrases occurred.
Since you have access to the paper under discussion,
can transcribe (a quote, not a paraphrase) sentences and formulas referring to the "mass of the photon"?

It seems to me that this author's approach has a nonzero "mass of the photon", which is at odds with our current understanding.

 

[name123]

From a google search of similarly titled papers by the author, some troubling phrases occurred.
Since you have access to the paper under discussion,
can transcribe (a quote, not a paraphrase) sentences and formulas referring to the "mass of the photon"?

It seems to me that this author's approach has a nonzero "mass of the photon", which is at odds with our current understanding.

The mass of a photon is referred to quite often. I've private messaged you.

 

[robphy]

The mass of a photon is referred to quite often. I've private messaged you.

Because of this, I feel that this (and possibly other conclusions)
would classify this as a non-mainstream theory.

TL;DR Summary: My question is, does the AEST approach work, while preserving proper time momentum, and flat Euclidean spacetime (even with gravity), or are there problems with it?

So, as I am sure other earlier responses have suggested, there are problems with it.
So, I think this question has been answered.

While aspects of it may be of interest,
I do not think this Special and General Relativity forum is the appropriate place to continue an extended discussion on it and its many facets.It may be appropriate to discuss one clearly-defined issue at a time,
but not a whole set of issues arising from a non-mainstream theory.

This is just my opinion... but I came to PhysicsForums because I wanted to focus on mainstream physics.

 

[Dale]

I don't see any incompatibility there

That is more of a problem than anything else.

You have had several problems pointed out. And with a handwaving “absolute spacetime solves all of my problems” (I am not convinced on that point) you march on and use relative spacetime when it suits.

You are trying to have your cake and eat it too. Either you have a relative spacetime with all of the acknowledged problems and you can adopt a convention of rest or you have an absolute spacetime and you cannot adopt a convention of rest (even if the absolute spacetime doesn’t solve the acknowledged problems)

But without any experimental way of determining whether an object is at rest in relation to absolute spacetime, those using the model by convention just assume one to be to get the results.

And this really doesn’t work. Since you cannot know which is the absolute frame but since only the absolute frame supposedly fixes the problems then you can never know if you have fixed the problems.

The foundations of this approach are shaky and full of holes.

Can you explain how the absolute frame supposedly fixes all of the problems identified above? I remain very skeptical

 

[Dale]

It seems to me that this author's approach has a nonzero "mass of the photon", which is at odds with our current understanding

And at odds with current experimental evidence.

 

[Dale]

For a point of organization, let’s leave off the photon mass discussion, and focus on the “Euclidean spacetime” (space-proper time) issues. The community has identified the following problems with the space-propertime approach:

1) the points are not themselves physically meaningful

2) worldlines intersecting doesn’t imply nearby objects and vice versa

3) causes can come after effects

4) light rays retrace themselves making a light clock essentially impossible to analyze

5) the concept doesn’t even apply for light rays since it gives a division by zero

6) (did I miss any?)

It is claimed that “absolute” Euclidean spacetime somehow solves those problems. How? I really don’t see it.

 

[robphy]

For a point of organization, let’s leave off the photon mass discussion, and focus on the “Euclidean spacetime” (space-proper time) issues.

Possibly useful: a very-old thread where the author is referenced in #4, #8, and later https://www.physicsforums.com/threads/wheres-the-catch.151075/

 

[name123]

For a point of organization, let’s leave off the photon mass discussion, and focus on the “Euclidean spacetime” (space-proper time) issues. The community has identified the following problems with the space-propertime approach:

1) the points are not themselves physically meaningful

2) worldlines intersecting doesn’t imply nearby objects and vice versa

3) causes can come after effects

4) light rays retrace themselves making a light clock essentially impossible to analyze

5) the concept doesn’t even apply for light rays since it gives a division by zero

6) (did I miss any?)

It is claimed that “absolute” Euclidean spacetime somehow solves those problems. How? I really don’t see it.

1) The points do make it meaningful that there is a physical distinction between proper time and the time parameter in the model, even if it isn't possible to establish what is at rest in absolute spacetime. Thus a photon would be thought to move in absolute time, but not in proper time.

2) World lines intersecting in which Fig that I supplied?
In Fig 2 they would imply being in exactly the same parameter time at the point of intersection, and there would be 0 spacetime distance.
If Fig 3 the line length will tell you whether they are at the same point in parameter time, and they would be 0 spatial distance I think, though there could be a distance in proper time.
In Fig 4, the Minkowski diagram, they would be at exactly the same parameter time, and there would be be 0 spatial distance, but you couldn't tell by looking whether there was any distance in proper time.

3) The paper explicitly denies this is the case. But please explain how that is so given that the angle can't be larger than 90 degrees, or rather if it is then in AEST theory (but not I guess in relative Euclidean geometry), as I mentioned, a particle is interpreted as the reversal of intrinsic properties such as charge and spin.

4) Light rays would only appear to retrace themselves in Fig 3 because their movement in parameter time is not shown. That would not be the case for Fig 2 or Fig 4.

5) What concept doesn't even apply for light rays?

 

[Vanadium 50]

one journal, Physics Essays. How high is it ranked?

A favorite of crackpots. I imagine they rank it highly. The rest of us, not so much.

 

[Dale]

The points do make it meaningful that there is a physical distinction between proper time and the time parameter in the model

There is already a distinction between coordinate time and proper time. That is not relevant.

The issue is that the space-propertime diagram is composed of points that have no physical meaning. If you dispute this then kindly write down the physical meaning of the points. What distinguishes one point in space propertime from another?

Physically different points in spacetime represent things that happened at different times (physically measured with clocks) or different places (physically measured with rulers). It is a clear physical meaning. There is no similar interpretation for space propertime that I know. Two different points in space propertime can happen at the same time and place.

World lines intersecting in which Fig that I supplied?

E.g. in the figure that @Ibix supplied.

But please explain how that is so given that the angle can't be larger than 90 degrees

Look at the diagram by @Ibix The points where the two traveling twins meet the home twin are the same event. A signal from the “later” one could be sent to the “earlier” one.

Light rays would only appear to retrace themselves in Fig 3 because their movement in parameter time is not shown

Once you include coordinate time as an axis, the diagram is no longer Euclidean.

What concept doesn't even apply for light rays?

The foundational idea that all objects travel through space propertime at $c$.

Anyway, it is becoming clear that you are not interested in learning what is wrong with this concept. You simply want to promote it.

I see little value in continuing this thread. Your stated question has been answered.

 

[Sagittarius A-Star]

Two different points in space propertime can happen at the same time and place.

As @Ibix already showed, an example for this can be seen in the Epstein diagram of the twin paradox. When the twins meet again, $A$ has aged by 26 years and $B$ only by 10 year. Therefore, they are shown at different points on the $\tau$ axis.

Source (see points A and B):
https://www.relativity.li/en/epstein2/read/c0_en/c7_en

 

[name123]

There is already a distinction between coordinate time and proper time. That is not relevant.

So photons don't move through proper time in TR?

I thought Montanus was pointing out that in the Minkowski Diagram (Fig 4 attachment #55) the time is actually the parameter time, and in TR that is proper time I thought. And I thought the photons did move in that time in TR. If that is so then that is a clear physical difference between the two models, and why I guess Montanus was pointing out that people in TR had mistaken it for a spacetime diagram.

The issue is that the space-propertime diagram is composed of points that have no physical meaning. If you dispute this then kindly write down the physical meaning of the points. What distinguishes one point in space propertime from another?

Physically different points in spacetime represent things that happened at different times (physically measured with clocks) or different places (physically measured with rulers). It is a clear physical meaning. There is no similar interpretation for space propertime that I know. Two different points in space propertime can happen at the same time and place.

I was under the impression that the different points in spacetime represent things that happened at different time (measured by clocks), or different places (physically measured with rulers).

A bit like with Newtonian physics. Where space and time were considered absolute. There was still the issue of a frame of reference with space. And there is still that issue with a frame of reference for space with space-propertime. I was under the impression that the difference with Newtonian physics and space-propertime was that the clocks could not be expected to all tick at the same rate. The rate at which the clocks would tick would depend on the velocity in space, since as mentioned the theory does contain the postulate that: in the absence of gravitation all objects move with a four dimensional Euclidean velocity equal to the speed of light in a vacuum. Thus the more one moves in the space dimensions, the less one will be moving in the proper time dimension. And that will be reflected in the time that one clock ticks compared to another.

E.g. in the figure that @Ibix supplied.

Look at the diagram by @Ibix The points where the two traveling twins meet the home twin are the same event. A signal from the “later” one could be sent to the “earlier” one.

Once you include coordinate time as an axis, the diagram is no longer Euclidean.

The foundational idea that all objects travel through space propertime at $c$.

It seems to me that you have misunderstood the diagram. But I realise it could be me that is having a problem understanding what you are saying.

If you look at the diagrams I supplied in #55. The diagram supplied by @Ibix is a Fig 3 type diagram. But look at a Fig 2 type and imagine that type of diagram of it. It would be clear that the when the twins meet back up it is at the same parameter time. One wasn't earlier. What the difference in proper time in Fig 3 type diagram represents is that the proper time of one twin is different to the proper time of the other. That their proper times are different isn't a causality issue.

Anyway, it is becoming clear that you are not interested in learning what is wrong with this concept. You simply want to promote it.

I see little value in continuing this thread. Your stated question has been answered.

Seems strange you would say that when I answered each thing you wrote.