Do AEST (Absolute Euclidean Spacetime) models work?

[PeterDonis]

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

In standard relativity, the concept of "proper time" is not even applicable to photons. Lightlike objects are fundamentally different physically from timelike objects. The concept of "proper time" is only applicable to timelike objects.

I thought Montanus was pointing out that in the Minkowski Diagram (Fig 4 attachment #55) the time is actually the parameter time

It is coordinate time in whatever inertial frame the diagram is being drawn.

in TR that is proper time I thought.

No. Coordinate time is not the same as proper time in standard relativity.

It appears that not only do you not understand AEST, you also don't understand standard relativity.

And I thought the photons did move in that time in TR.

In any inertial frame, points on a photon's worldline map one-to-one with values of coordinate time. But, as above, coordinate time is not the same as proper time, and the concept of "proper time" is not even applicable to photons.

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).

That's true, but it's beside the point. If two worldlines in spacetime meet at a single point, that means those two objects physically met each other. But if two "worldlines" in space-propertime meet at a single point, that tells you nothing physically at all. That's the objection @Dale was making. You have not answered it.

when the twins meet back up it is at the same parameter time.

The same coordinate time in any inertial frame. Or, more important, the same point in spacetime.

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.

No, but it is an issue for space-propertime, since it means a single physical event--the two twins meeting up again--is not represented by a single point in space-propertime. This is one illustration of the fact, already mentioned, that points in space-propertime have no physical meaning, unlike points in spacetime.

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

No, you haven't. You have answered nothing whatever. See above.

 

[PeroK]

It appears that not only do you not understand AEST, you also don't understand standard relativity.

This was evident in the long, painful thread on the Hafele-Keating experiment:

https://www.physicsforums.com/threads/hafele-keating-experiment.1007512/

 

[name123]

In standard relativity, the concept of "proper time" is not even applicable to photons. Lightlike objects are fundamentally different physically from timelike objects. The concept of "proper time" is only applicable to timelike objects.

Ok, well there is a difference there then. In AEST proper time is applicable to photons. It is just that they don't move through it. And I assume in AEST there is no distinction between lightlike objects and timelike objects. And that there is no need to perform the operation you did in

[PeterDonis didn't write this, just not sure how else to provide link to post]

It is coordinate time in whatever inertial frame the diagram is being drawn.

I think that was what Montanus was considering a mistake that has taken place in TR. That from the diagrams I supplied in #55 you can see where the Minkowski diagram comes from. I'll just requote what his thoughts on it were.

"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. Unfortunately this is the situation in the TR. Together with the aforementioned inconsistent definition of distances it leads to an illogical and contradictive model for spacetime."

But you seem to be stating that in TR when establishing the coordinate time of an observed object in a different frame of reference, the proper time of the observer is not a parameter. And therefore he is wrong to think that the Minkowski diagram is actually a space diagram extended with a parameter axis.

That's true, but it's beside the point. If two worldlines in spacetime meet at a single point, that means those two objects physically met each other. But if two "worldlines" in space-propertime meet at a single point, that tells you nothing physically at all. That's the objection @Dale was making. You have not answered it.

I thought I gave quite an extensive answer, which evolved explaining that the information it gave depended on what type of diagram the worldline was in. And explained the difference whether it was a Fig 2 type, Fig 3 type, of Fig 4 (Minkowski) type.

Regarding the Fig 3 type explanation you even wrote:

No, but it is an issue for space-propertime, since it means a single physical event--the two twins meeting up again--is not represented by a single point in space-propertime. This is one illustration of the fact, already mentioned, that points in space-propertime have no physical meaning, unlike points in spacetime.

Ok, it seems to me that space-propertime is compatible at least with a past present future conception of time (I actually cannot see how else to view it without considering it to have 5 dimensions, but that might just be me). If so then the 4D Euclidean spacetime replaces the 3D Euclidean space of Newtonian physics. And thus for any point in parameter time, if two entities have the same space coordinates they will have met up. But, in the 4D Euclidean spacetime used, it wouldn't be a point like in the 3D space used in Newtonian physics, as there is an extra dimension, propertime. And so in the 4D Euclidean spacetime it would be a line. A line on which all points have the same space coordinates, but which have different propertime coordinates. As people could meet up with a range of different values on their clocks. And going further, it also seems to me as a layperson, propertime seems to reflect the idea of clocks slowing down when they move relative to absolute spacetime.

 

[Dale]

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

You still have not addressed my key point from my very first post which I have repeated multiple times. If you were interested in learning you would try it, but you are interested in pushing your concept.

Please provide a physical description of what physically distinguishes two points in space-propertime. What is the physical meaning of points in such a diagram?

Spacetime has physical meaning, space propertime does not. You are arguing without learning.

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

Proper time is not defined on a null worldline. Instead an affine parameter must be used.

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.

See, here you are just making a weak argument rather than saying "oh yes, that is a problem". A space-propertime diagram, as shown by @Ibix, is very problematic. We tell you it is problematic and your response is not to say "yes it is problematic" but to say "well a different kind of diagram is not problematic". Pointing to a spacetime-propertime diagram doesn't fix a space-propertime diagram. It tacitly acknowledges the problem. If a space-propertime diagram worked then why would they need to introduce a spacetime-propertime diagram?

The issue is that a space-propertime diagram is very unnatural and non-physical. As I mentioned above and which you still have not addressed there is no physical meaning to the points in a space-propertime diagram. The points in a spacetime diagram have a physical meaning and the worldline parameters also have a physical meaning in spacetime.

It makes no sense to treat the parameters as a coordinate. For one, each worldline has its own parameter, that is why we can use proper time for timelike worldlines and an affine parameter for lightlike worldlines. For two, that parameter is only defined along that worldline, so it doesn't make sense to treat it as though it were defined elsewhere. It is inherently problematic to represent proper time as it is represented in a space propertime diagram.

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

Here is the issue. See the annotated diagram. Points A, B, and C are the same event. That is the first collision/reunion event. A pulse of light emitted at point D can affect points A, B, and C. So it is clear that in this presentation effects (A) can precede causes (D). Remember, worldlines in a space-propertime diagram don't have to intersect to actually be at the same place and time, so the fact that lightlike lines go at 90 degrees has no bearing on whether or not effects can precede the cause.

 

[A.T.]

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.

The way Carroll L. Epstein introduces it (here is the book online version), it is definitely just a different geometrical interpretation of the same SR & GR math. Basically a different type of diagram showing some things that a Minkowski-Diagram doesn't, but also missing some things.

 

[A.T.]

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.

Different types of diagrams have different interpretations for elements in them. In classical physics we use different diagrams too: time-position, time-velocity, position-velocity, ... Nobody is expecting that all diagram elements like points, path lengths or path crossings have the same physical meaning in all of them, or are equally meaningfull.

 

[Dale]

Nobody is expecting that all diagram elements like points, path lengths or path crossings have the same physical meaning in all of them, or are equally meaningfull.

Yes, the graphical elements of different diagrams have different meanings, that is in fact the concept I am trying to convey. It seems that the OP does expect that the points in a space-propertime diagram are physically meaningful, despite my harping on this issue non-stop.

 

[Dale]

Ok, it seems to me that space-propertime is compatible at least with a past present future conception of time

It does not. The past present future organization is discarded as I showed above in the annotated version of @Ibix 's diagram.

going further, it also seems to me as a layperson, propertime seems to reflect the idea of clocks slowing down

It does indeed do this, but that is all it does. That is why we are showing other examples of things it does not do. If you want to claim that something "works" then you probably need to specify what you claim it works for. As a general model of physics, it does not work. As a nice graphical indicator of time dilation it does work, and that is about it.

And thus for any point in parameter time, if two entities have the same space coordinates they will have met up

And as soon as you introduce SR's coordinate time $t$ then you are no longer using a space-propertime diagram and no longer using a Euclidean metric. In order to make the space-propertime diagram work for more than just time dilation you have to augment it with coordinate time. It is then no longer Euclidean and it is no longer space-propertime. The need to do this shows the stringent inherent limitations that you have yet to acknowledge about a space-propertime diagram.

 

[A.T.]

Yes, the graphical elements of different diagrams have different meanings, that is in fact the concept I am trying to convey. It seems that the OP does expect that the points in a space-propertime diagram are physically meaningful, despite my harping on this issue non-stop.

Okay, clarifying this is important. But I don't see it as an argument against using space-propertime diagrams, along with space-coordinatetime diagrams. Some diagram elements are more meaningful in a space-propertime diagram, where the path length is the coordiante-time interval. In a space-coordiantetime diagram the path length has no directly interpretable meaning, and you need additional math to compute the proper-time interval from it.

 

[robphy]

Okay, clarifying this is important. But I don't see it as an argument against using space-propertime diagrams, along with space-coordinatetime diagrams. Some diagram elements are more meaningful in a space-propertime diagram, where the path length is the coordiante-time interval. In a space-coordiantetime diagram the path length has no directly interpretable meaning, and you need additional math to compute the proper-time interval from it.

Bolding above by me.
Sure, one can have supplementary drawings and plots (like space-propertime or space-space or whateverElse-whateverElse2).
But
one cannot dispense with the Minkowski spacetime diagram (with its Minkowskian spacetime geometry) for special relativity, as these many alternative approaches attempt to do.

 

[Dale]

I don't see it as an argument against using space-propertime diagrams, along with space-coordinatetime diagrams

Nor do I. It is fine to use space-propertime diagrams for what they are useful for.

They are not useful as a Euclidean spacetime to replace standard Minkowski spacetime. Space-propertime is not simply a Euclidean spacetime. This thread is about whether or not “Euclidean spacetime” works. The OP and his favorite author don’t want to just use space-propertime diagrams for what they are useful for, but rather as a Euclidean replacement for spacetime. The point I am making about the points is crucial for understanding why that overly ambitious goal doesn’t work.

 

[PeterDonis]

In AEST proper time is applicable to photons. It is just that they don't move through it.

And this means that points in space-propertime can't have any physical meaning for light, any more than they do for timelike objects.

I assume in AEST there is no distinction between lightlike objects and timelike objects.

First, you shouldn't assume. You should know. If you don't know even something as basic as that about AEST, what's the point of this thread? Aren't you just wasting everyone's time?

Second, the distinction between lightlike and timelike objects is a physical distinction. You can observe it in experiments. One obvious observation is that you can't change your speed relative to a lightlike object: if you accelerate towards it, it doesn't slow down relative to you, as a timelike object does, it blueshifts. Any theory that does not capture this obvious physical difference is just wrong.

And that there is no need to perform the operation you did in

I have no idea what you are talking about here.

I think that was what Montanus was considering a mistake that has taken place in TR.

Montanus' claim that there is a mistake in standard relativity is one of the main reasons why he is considered a crackpot. The standard spacetime model of relativity makes precise quantitative predictions about experimental results that have been verified to many decimal places. That includes the parts of the model that Montanus claims contain a "mistake".

I'll just requote what his thoughts on it were.

Montanus' thoughts here look like word salad to me. He is trying to claim that standard spacetime diagrams in flat Minkowski spacetime are somehow invalid. That doesn't even pass the laugh test. Again, the fact that he makes such claims with apparent seriousness is one of the main reasons why he is considered a crackpot. It's as if he were to claim that standard arithmetic is somehow wrong because mathematical objects like 1, 2, and 3 actually aren't valid numbers.

you seem to be stating that in TR when establishing the coordinate time of an observed object in a different frame of reference, the proper time of the observer is not a parameter.

Your statement here doesn't make sense. There is no such thing as "the coordinate time of an observed object". Coordinate times belong to events, not objects.

As for transforming the coordinates of events from one inertial frame to another, it should be obvious from the Lorentz transformation equations that "proper time" is not a parameter in such transformations.

I thought I gave quite an extensive answer

You thought wrong. That's because, as I have already stated, you do not appear to have a good understanding either of AEST or of standard SR. Which, again, makes me wonder if this whole thread is not a waste of time. Maybe Montanus himself could come here and at least give some kind of substantive response to the concerns being raised (though from what I've read so far of what he wrote, I doubt it). But he's not posting here, you are, and it certainly doesn't seem like you can. So what's the point?

it seems to me that space-propertime is compatible at least with a past present future conception of time (I actually cannot see how else to view it without considering it to have 5 dimensions, but that might just be me). If so then the 4D Euclidean spacetime replaces the 3D Euclidean space of Newtonian physics. And thus for any point in parameter time, if two entities have the same space coordinates they will have met up. But, in the 4D Euclidean spacetime used, it wouldn't be a point like in the 3D space used in Newtonian physics, as there is an extra dimension, propertime. And so in the 4D Euclidean spacetime it would be a line. A line on which all points have the same space coordinates, but which have different propertime coordinates. As people could meet up with a range of different values on their clocks. And going further, it also seems to me as a layperson, propertime seems to reflect the idea of clocks slowing down when they move relative to absolute spacetime.

All of this looks like word salad to me.

 

[PeterDonis]

Thread closed for moderation.

 

[PeterDonis]

After moderator discussion, this thread will remain closed. The OP question has been addressed. Thanks to all who participated!