The Relativity of Simultaneity: A Fundamental Concept in Special Relativity

[mangaroosh]

Again, I genuinely believed that the questions posed were simple, yes or no, questions.

I think this is a bad approach in principle. How can you hope to gain a better understanding of a well-defined theory like SR by discussing poorly defined concepts like presentism.

What are the experimental consequences of presentism, or is it merely a philosophical viewpoint?

If there are experimental consequences then it should be possible to mathematically derive whether or not the RoS is compatible with it, and if so then it is incorporated in both LET and SR.

If it is merely a philosophical viewpoint with no experimental consequences then the first question is clearly "yes" since it would be compatible with any experimental feature of any theory.

The intention is to better understand what the necessary consequences of the Lorentz transform are; where there are two theories that use the same transform it is necessary to contrast them to help determine what the necessary consequences of that transform are. If there are certain, specific aspects of one theory that are not present in the other, then we can logically deduce that they are not necessary consequences of the transform.


I'm fairly sure that you are relatively familiar with the concept of presentism; the idea that there is a single universal present moment, common to all observers. You may also be aware of the A- and B-theories of time; presentism conforms to the A theory. This article might help to illucidate it more. We also don't necessarily need to mathematically derive if it is compatible with RoS; by examining the concepts we can determine if they are compatible or not.

I know that I've read in another thread, on here, where you have clearly stated that the difference between LET and Einsteinian relativity is philosophical, and that it is essentially a matter of choice which one chooses; given the experimental equivalence of both.

So, although the experimental features of LET are entirely compatible with Einsteinian relativity, they are philosophically quite different. In order to determine what the necessary consequences of the Lorentz transform are, we need to examine some of those concepts.


Are you familiar with the concept of presentism, at all; and is it incorporated into LET, do you know?

 

[GeorgeDishman]

Hmm, not really. If you post that in the QM group you will certainly find that some experts disagree with you about light being a particulate that is incompatible with wave theory;

Oh certainly, I wasn't referring to modern QM but to the idea of light as being waves in the luminiferous aether.

and while GR was meant to remove the absolute sense of acceleration, this is not widely accepted nowadays

I think the Equivalence Principle is still fundamental to an understanding of GR. Anyway my specific source would be d'Inverno:

https://www.amazon.com/dp/0198596863/?tag=pfamazon01-20

There's a table showing what is absolute and what is relative in the various theories. Sorry I don't have a page reference available at the moment.

(you could start a topic on that; meanwhile see for example the physics FAQ: http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_gr.html).

From that page:

Although most scenarios in Special Relativity are most easily described using inertial frames, there is no reason why these frames absolutely must be used. The Equivalence Principle analysis of the twin paradox simply views the scenario from the frame in which Stella is at rest the whole time. This is not an inertial frame; it's accelerated, so the mathematics is harder. But it can certainly be done. When the mathematics is described fully, what results is that we can treat a uniformly accelerated frame as if it were an inertial frame with the addition of a "uniform pseudo gravitational field". By a "pseudo gravitational field", we mean an apparent field (not a real gravitational field) that acts on all objects proportionately to their mass; by "uniform" we mean that the force felt by each object is independent of its position. This is the basic content of the Equivalence Principle.​

 

[harrylin]

[..] I'm not fully clear on what you mean by "differing definitions of distant simultaneity". [..] The definition of RoS that I have been working off, as I think we've clarified at this stage, is that events which are simultaneous in one reference frame can be non-simultaneous in another.

That's the same thing: a differing (=disagreeing) definition of distant simultaneity has as consequence that distant events that "are" simultaneous in the one reference frame, "are" non-simultaneous in the other (note again that in SR no philosophical "is" or "are" exist).

I'm not sure I can relate the two points above to the questions posed. Is the first point addressing the question of, "is RoS compatible with presentism?" [..]

Instead, it simply tells you that this presentation introduces the RoS of relativity as fact.

Is the second point addressing the question of presentism and LET? [..]

Together with the first point, it answers the question if the RoS of relativity is compatible with a Lorentz ether. And as you know, the Lorentz ether supports such philosophical ideas as a metaphysical "absolute time" (although not measurable).

 

[Dale]

Again, I genuinely believed that the questions posed were simple, yes or no, questions.

Even simple yes or no questions may be unclear. As in "Are flubnubbits always red?" Simple yes or no questions may also be themselves logically unsound, such as "Have you stopped beating your wife yet?". Your yes or no question is of the former type, unclear. Which is why I asked for clarification:

What are the experimental consequences of presentism, or is it merely a philosophical viewpoint? (the link you posted seems to indicate that it is merely a philosophical viewpoint)

Please clarify your meaning of the word "presentism".

Are you familiar with the concept of presentism, at all; and is it incorporated into LET, do you know?

I have heard the word, but I have never used nor studied the concept, which is why I asked for clarification and also why I think that it is not necessary to a proper understanding of SR.

 

[mangaroosh]

That's the same thing: a differing (=disagreeing) definition of distant simultaneity has as consequence that distant events that "are" simultaneous in the one reference frame, "are" non-simultaneous in the other.

Ah, OK, I didn't get that.

Instead, it simply tells you that this presentation introduces the RoS of relativity as fact.

Forgive me if I leave that for the time being

Together with the first point, it answers the question if the RoS of relativity is compatible with a Lorentz ether. And as you know, the Lorentz ether supports such philosophical ideas as a metaphysical "absolute time" (although not measurable).

Apologies, I couldn't discern that.

But just in relation to the question, is presentism, specifically, incorporated into LET?

Apologies for assuming you are familiar with the concept of presentism, if you are not.

 

[harrylin]

Here we deviate too far from the topic (again, please start a topic of this if you want), so my last comments on these topics here:

Oh certainly, I wasn't referring to modern QM but to the idea of light as being waves in the luminiferous aether.

I fear that possible disproof would be identical; it's quite similar as with Mangaroosh's questions.

I think the Equivalence Principle is still fundamental to an understanding of GR. [..]

There is no issue with the EP, except if you insist that what nowadays are called "pseudo fields", are in fact "real" fields - as discussed in the link that I provided.

 

[harrylin]

[...] But just in relation to the question, is presentism, specifically, incorporated into LET? Apologies for assuming you are familiar with the concept of presentism, if you are not.

Sorry, I'm not familiar with the concept of presentism and disagree with the "LET" concept.

 

[mangaroosh]

Hey George, thanks for the replies; hopefully you can bare with me because I think I'm getting closer to being able to explain my perspective; it is a bit frustrating for me, because I am having dificulty putting my understanding into precise language that might cut through any misunderstanding. I find it is a bit like learning a new language, I can understand more than I can articulate, but through practice I develop the latter ability.

My previous reply sort of missed the point of this question.

IMHO, the term "relativity of simultaneity" in LET refers to measured times. It is therefore unrelated to and independent of any choice of philosophical interpretation such as Presentism.

The term "relativity of simultaneity" as I understand it, and as has been discussed in this thread, refers to the idea that events can be simultaneous for one observer and not simultaneous for another. This leads to the idea that there is no single, universal present moment, commone to all observers.

If presentism is incorporated in LET, then the above description of RoS is not compatible with LET.

That would mean that RoS has two distinct meanings, which are not necessarily compatible with each other.

BTW, if you want to discuss the philosophical side, this is the wrong forum.

This forum is for people who wish to expand their understanding of relativity, and doesn't preclude the philosophical aspects of the theory, I don't think.

Let's see if I can put my answer in more practical terms. Consider an observer, Alice, who has a long rigid pole with a clock at each end, A and B. She uses some practical physical technique to synchronise the clocks, for example by sending a light pulse from A to B where it is immediately reflected back to A. If the time of the pulse being reflected at B is midway between the send and receive times at A, the clocks are defined as being synchronised. A second observer, Bob, traveling past this setup who uses the same technique determines that the clocks are not synchronised. The determination is therefore related to the motion of the observer. That is called the relativity of simultaneity.

1) Can you see that the Lorentz Transforms can be used to calculate by how much Bob will consider the clocks to differ from being synchronised?

2) Can you see that the above scientific definition of synchronisation is independent of any philosophical musing on the nature of time?

I can see how the LT allows Bob to do the calculations. But my understanding of RoS is that it refers more to the simultaneity of events i.e. events could be simultaneous according to Bob, but Alice would disagree.

If we take the asynchronicity of clocks, but assume presentism, then the events would either be simultaneous, or not, regardless of the asynchronicity of the clocks.

If the asynchronicity of the clocks is used to determine RoS, then it requires certain philosophical assumptions about the nature of time.

Our posts crossed, sorry for the slight duplication.

No, AIUI the Block Universe is considered a version of eternalism while the Moving Spotlight is a version of presentism. The perception of the flow of time is a more complex question perhaps related to the arrow of time and certainly connected with the fact that we only remember in one direction, pastwards.

My apologies, I have a different notion of "time" in my head with regard to presentism, so I misread the moving spotlight point.

I think the perception of the flow of time is indeed connected to the fact that we only remember the past, and project the future, but I think the issue of perception of relative motion for static worldlines, in a block universe is much more complex than that.

It is not necessarily required, there are other versions of presentism.

again, apologies, that was my misinterpretation of what you said. I was referring more to the block universe and an explanation for how static world lines perceive motion and change.

Correct so far.

The error you are making is in grasping what "relativity of simultaneity" means. As I explained in my previous post, it refers to the practical synchronisation of clocks which is governed by the Lorentz Transform.

The concept of RoS we have been working off, in this thread, incorporates the synchronisation of clocks, but refers to where events can be simultaneous for one observer and not simultaneous for another; this leads to the conclusion that there is no single, universal present moment commone to all observers. That would mean that RoS is not compatible with presentism.

If presentism is incorporated into LET, then RoS cannot be a necessary consequence of the lorentz transform - as far as I can deduce anyway; but there may be an issue with my logic.

OK, in my previous reply I have tried to isolate the LTs from both the philosophical aspects and the choice of interpretation. You still need the understanding of the transforms but it can be reduced to a "shut-up-and-calculate" (SUAC) philosophy, just put in the numbers, turn the handle and see what you get.

The issue is that the LT is used in two theories with two quite different philosophical interpretations, so when determining if certain philosophical concepts are necessary consequences of the LT, it isn't practical to isolate the LT from the philosophy.

 

[mangaroosh]

Even simple yes or no questions may be unclear. As in "Are flubnubbits always red?" Simple yes or no questions may also be themselves logically unsound, such as "Have you stopped beating your wife yet?". Your yes or no question is of the former type, unclear. Which is why I asked for clarification:

What are the experimental consequences of presentism, or is it merely a philosophical viewpoint? (the link you posted seems to indicate that it is merely a philosophical viewpoint)

Please clarify your meaning of the word "presentism".

Presentism refers to the idea that there is a single, universal present moment, common to all observers.

This would be contrasted with the idea that there is no single, universal present moment, common to all observers; which is a consequence of RoS.

Assuming that the above is an accurate representation of the concept of presentism, would you agree that those two concepts are incompatible?

I have heard the word, but I have never used nor studied the concept, which is why I asked for clarification

It might be worth asking GeorgeDishman for further clarification, as he appears to be familiar with the concept, and may be better able to clarify it that I can, or he might just be able to put it in terms that are more meaningful to you.

and also why I think that it is not necessary to a proper understanding of SR.

This seems to be a recurring point, which I thought I had addressed, but maybe not. Hopefully I can clarify it though.

The topic in question relates to the necessary consequences of the Lorentz transform, which is an integral part of Einsteinian relativity. Considering a second, experimentally equivalent, theory, which also uses the Lorentz transform, can help us to deduce what the necessary consequences of the LT are, thereby expanding our understanding of the LT, with it, Einsteinian relativity.

I refer to the collective "us", not necessarily you and I.

 

[harrylin]

[..]
Apologies for assuming you are familiar with the concept of presentism, if you are not.

PS: I already referred you to Einstein's 1905 paper, and how with only a few small changes of formulation one obtains a version that would have been to Lorentz's taste.

So here are two simple questions to you:
- Do you agree that Einstein's 1905 paper refers to RoS?
- Do you agree that Lorentz believed in "true time"?

Your answer on those questions will surely also answer your own questions.

Harald

 

[mangaroosh]

Sorry, I'm not familiar with the concept of presentism and disagree with the "LET" concept.

The concept of presentism refers to the idea that there is a single, universal present moment, common to all observers.

Assuming this is an accurate representation of "presentism", would you agree that it is incompatible with RoS, which leads to the conclusion that there is no single, universal present moment, common to all observers?


With regard to your disagreement with the LET concept (I presume you refer to the theory as opposed to the concept of presentism), I've read on this site that it is a matter of philosophical preference which you choose to accept, so I don't think there is any issue with regard to your acceptance of it. The question relates to the incorporation, or otherwise, of the concept of presentism in LET.

The impression I have gotten from discussing LET, on this site, is that it does incorporate the concept of presentism.

 

[mangaroosh]

PS: I already referred you to Einstein's 1905 paper, and how with only a few small changes of formulation one obtains a version that would have been to Lorentz's taste.

So here are two simple questions to you:
- Do you agree that Einstein's 1905 paper refers to RoS?
- Do you agree that Lorentz believed in "true time"?

Your answer on those questions will surely also answer your own questions.

Harald

I agree on both counts, but again, I can only ask you to supply a direct answer, because I cannot deduce the answer from what you allude to.

The issue might perhaps lie in the unfamiliarity with the concept of presentism, however.

 

[mangaroosh]

@Harry and Dale

just wondering if you guys are familiar with Newtonian physics; am I right in saying that Newton's theory incorporated absolute space and time, as well as the idea of a single, universal present moment?

I ask bcos I presume there may perhaps be a greater level of familiarity with that theory, than LET, perhaps.

 

[harrylin]

I agree on both counts, but again, I can only ask you to supply a direct answer, because I cannot deduce the answer from what you allude to.

The issue might perhaps lie in the unfamiliarity with the concept of presentism, however.

Perhaps; I can only assume that "presentism" corresponds to "true time". If so, then the fact that Einstein's relativity paper (certainly the part on RoS) is compatible with Lorentz's views makes you already know that the RoS of Einstein's paper is compatible with presentism.

[..] just wondering if you guys are familiar with Newtonian physics; am I right in saying that Newton's theory incorporated absolute space and time, as well as the idea of a single, universal present moment?

Yes and yes (I even referred you to that); and Lorentz's metaphysics was based on such concepts, despite the fact that he introduced "local time" - which includes RoS.

 

[mangaroosh]

Perhaps; I can only assume that "presentism" corresponds to "true time". If so, then the fact that Einstein's relativity paper (certainly the part on RoS) is compatible with Lorentz's views makes you already know that the RoS of Einstein's paper is compatible with presentism.


Yes and yes (I even referred you to that); and Lorentz's metaphysics was based on such concepts, despite the fact that he introduced "local time" - which includes RoS.

Is the idea of a single, universal present moment compatible with the idea that there is no single, universal present moment?

 

[yuiop]

Is the idea of a single, universal present moment compatible with the idea that there is no single, universal present moment?

If I rephrase your question like this:

"Is the idea of a single, (unmeasurable) universal present moment compatible with the idea that there is no single, (measurable) universal present moment?",

then the answer is yes.

 

[mangaroosh]

Hey yuiop.

i don't think your re-statement addresses the issue-it a appears to just make it tautological.

We can simply re-order the adjectives to get,is the idea of an unmeasurable, single, present moment compatible with the idea that there is no measurable, single present moment?

Measurable or not, presentism-as described- would not be compatible with RoS (measurable or not).

 

[GeorgeDishman]

Perhaps; I can only assume that "presentism" corresponds to "true time".

No, crudely, presentism is the philosophy that things that exist are 3-dimensional and that time is an emergent property resulting from the perception of change. It contrasts with eternalism which considers that the past, present and future existence of entities are equally real. See here for a more rigorous introduction:

http://plato.stanford.edu/entries/temporal-parts/

However, I would suggest that you move the discussion to the philosophy forum

https://www.physicsforums.com/forumdisplay.php?f=112

and in particular the "Time: A-series or B-series?" thread.

 

[GeorgeDishman]

Hey George, thanks for the replies; hopefully you can bare with me because I think I'm getting closer to being able to explain my perspective; it is a bit frustrating for me, because I am having dificulty putting my understanding into precise language that might cut through any misunderstanding. I find it is a bit like learning a new language, I can understand more than I can articulate, but through practice I develop the latter ability.

Practice will help but in learning a new language, you also have to listen to people who already speak it when they tell you what the jargon terms mean where they are specific to that language.

The term "relativity of simultaneity" as I understand it, and as has been discussed in this thread, refers to the idea that events can be simultaneous for one observer and not simultaneous for another. This leads to the idea that there is no single, universal present moment, commone to all observers.

The term "relativity of simultaneity" is one of those jargon terms which has a very specific meaning and is not something you can reinvent for yourself if you want to communicate with people who already know the conventional definition. That is why I took the trouble to explain it to you carefully in the previous post.

If presentism is incorporated in LET, then the above description of RoS is not compatible with LET.

Presentism is not "incorporated in LET" as I again tried to explain before. Presentism is a philosophical view while LET is a scientific theory so the two are independent. Let's leave that topic for the philosophy forum.

That would mean that RoS has two distinct meanings, which are not necessarily compatible with each other.

No, it is a jargon term so has only one specific meaning which several people including myself have been patiently explaining to you for several weeks. You seem determined to avoid understanding it.

This forum is for people who wish to expand their understanding of relativity,

Indeed, but you have discussed nothing but LET's version of RoS and philosophy, there isn't a single comment related to relativity in anything you have posted.

and doesn't preclude the philosophical aspects of the theory, I don't think.

You have moved the presentism to the other forum so let's leave that there.

Let's see if I can put my answer in more practical terms. Consider an observer, Alice, who has a long rigid pole with a clock at each end, A and B. She uses some practical physical technique to synchronise the clocks, for example by sending a light pulse from A to B where it is immediately reflected back to A. If the time of the pulse being reflected at B is midway between the send and receive times at A, the clocks are defined as being synchronised. A second observer, Bob, traveling past this setup who uses the same technique determines that the clocks are not synchronised. The determination is therefore related to the motion of the observer. That is called the relativity of simultaneity.

1) Can you see that the Lorentz Transforms can be used to calculate by how much Bob will consider the clocks to differ from being synchronised?

2) Can you see that the above scientific definition of synchronisation is independent of any philosophical musing on the nature of time?

I can see how the LT allows Bob to do the calculations.

Bob doesn't exist, he's hypothetical. The LTs allow you to do the calculations.

But my understanding of RoS is that it refers more to the simultaneity of events i.e. events could be simultaneous according to Bob, but Alice would disagree.

Think about the words. Two clocks are sychronised if their ticks are simultaneous. The time when an event occurs is defined by the reading on a clock local to the event. That means that two events are simultaneous if their times are the same as measured by synchronised clocks or, to put it another way, if their time coordinates are the same. Work through those definitions carefully, we went over this some time ago but you still seem to be having trouble with it. I've repeated the description above because it is key to the context.

If we take the asynchronicity of clocks, but assume presentism, then the events would either be simultaneous, or not, regardless of the asynchronicity of the clocks.

No, that is where you are making you fundamental mistake, you are confusing your philosophy with the science. The phrase "relativity of simultaneity" refers to clock synchronisation, nothing else.

If the asynchronicity of the clocks is used to determine RoS, then it requires certain philosophical assumptions about the nature of time.

No, it refers to the nature of synchronisation of clocks which is an observable fact regardless of any philosophical interpretation.

My apologies, I have a different notion of "time" in my head with regard to presentism, so I misread the moving spotlight point.

So it seems, the references in the other forum should help you on that.

The concept of RoS we have been working off, in this thread, ...

You don't get to choose. The term has been defined for decades. Try learning what it means instead.

If presentism is incorporated into LET ...

It isn't. What I said was that if you assume presentism, you probably get LET but it doesn't follow the other way round. Anyway, let's leave presentism for the philosophy forum.

 

[Austin0]

Hi ,I don't know the historical evolution of RoS but I will give you my take on it.

It is a consequence of the second postulate , the measured invariance of c ,and Einsteins perception that our normal understanding and determination of simultaneity did not apply in a relativistic context. These conditions led to their implementation through the Synchronization Convention and the Lorentz math which charted the resulting relationships (asynchronicity) between clocks at different locations in different inertial frames.

is RoS compatible with Presentism?
Einstein demonstrated that our idea of simultaneity was indeterminable.
That it was meaningless to say (or think) any two spatially separated events were simultaneous in any absolute sense. But this is just as true if this is a presentistic (?) universe.

SO yes, RoS, is as compatible with presentism as it is with block time, as both are essentially philosophical or metaphysical concepts and questions.

Interesting in their own right but unverifiable and superfluous to the understanding and application of SR

IMO the very word simultaneous, with all it's deeply ingrained baggage, should be replaced with a term that had no implication of actual temporal significance. Clockronous maybe?

That appears to be a non-sequitir.

That our idea of simultaneity is indeterminable does not necessarily mean that RoS is compatible with presentism.

That is a non-sequitur as I clearly never said that. I stated that the condition of indeterminacy would be just as much a fact even if the universe was "actually" presentistic.

You mention the possibility that this could be a presentistic universe, suggesting that RoS is itself indeterminable, and therefore a philosophical, or metaphysical, concept. Again, that both are metaphysical concepts does not imply that they are compatible, because they appear to be contradictory philosophical concepts.

yes I cannot rule out the possibility that the universe is presentistic but that in no way suggests that RoS is indeterminable as it simply deals with what IS determinable i.e. Empirical measurements and observations; CLOCKS
At the risk of being redundant; the source of much of your confusion and difficulty in understanding what everybody has been telling you is that you are continually mixing apples and oranges.

Presentism and Block Time are philosophies.
These concepts ARE NOT compatible

SR and LET are scientific theories.
AS theories that that make the same empirical predictions they ARE compatible.

Some LETists are Presentists and some Relativitists are Block Timers but this is completely irrelevant to the Theories themselves.
Philosophically Newton was an Absolutist but as a scientist he was as much of a Relativitist as Einstein. The theories had no element of absolutism.

Presentism is the idea that there is a single universal present moment, common to all observers;

Right.

RoS is the idea that the present moment is relative to each observer and that no single, universal present actually, or necessarily, exists.

WRONG. RoS says absolutely nothing about a present moment or whether or not a universal present moment actually exists. It simply correlates proper time readings in differing
inertial frames.
Once again you are confusing two different interpretations of simultaneous.
RoS is the idea that the proper time reading is relative for each observer.
You are free to interpret this however you choose. Eg; There is a universal now and the clocks are all incorrectly desynchronized according to the universal instant.
RoS is not incompatible with that interpretation , it is merely irrelevant.

Am I right in saying that you are suggesting that RoS is unverifiable also?

No; block time and presentism are unverifiable

But block time is neither a necessary condition for , nor an inevitable logical derivation from RoS
They are mutually independent. But you seem to keep trying find a necessary correspondence and insisting there is one.

 

[mangaroosh]

Practice will help but in learning a new language, you also have to listen to people who already speak it when they tell you what the jargon terms mean where they are specific to that language.

The term "relativity of simultaneity" is one of those jargon terms which has a very specific meaning and is not something you can reinvent for yourself if you want to communicate with people who already know the conventional definition. That is why I took the trouble to explain it to you carefully in the previous post.
...
No, it is a jargon term so has only one specific meaning which several people including myself have been patiently explaining to you for several weeks. You seem determined to avoid understanding it.
...
No, that is where you are making you fundamental mistake, you are confusing your philosophy with the science. The phrase "relativity of simultaneity" refers to clock synchronisation, nothing else.
...
No, it refers to the nature of synchronisation of clocks which is an observable fact regardless of any philosophical interpretation.
...
You don't get to choose. The term has been defined for decades. Try learning what it means instead.

I haven't reinvented the term at all, the understanding I have of the term, as presented above, is something that has been discussed and agreed in this thread, with people who already know the conventional definition.

My understanding of RoS is that events which are simultaneous in one reference frame are not necessarily simultaneous in other reference frames i.e. if two events are not simultaneous in one reference frame it is possible that they are simultaneous in other reference frames. Is that accurate to any degree?

Yes.

I understand that RoS relates to the synchronisation of clocks, in Einsteinian relativity, at least. The question is whether or not it relates purely to the synchronisation of clocks - please don't simply reply with "it does" here, because I am trying to outline my understanding of why it might not; if it does, then it would apply equally to LET. The issue, however, lies in the fact that both theories make different, fundamental assumptions about the nature of time and what the synchronisation of clocks implies. That the clock synchronisation method relies on an untestable assumption i.e. the one way speed of light, makes it a philosophical consideration, not an experimentally verifiable one. This, in turn, makes RoS a philosophical consideration.

As with any philosophical concepts, there are certain implications as far as RoS is concerned. One such implication is that there is no universal present moment, common to all observers.

This concept is incompatible with the idea that there is a universal present moment i.e. presentism.

That remains a fact regardless of clock synchronisation.


The question is whether or not presentism is assumed/incorporated into LET; you seem to be offering somewhat contradictory opinions on this, but we can look at them below.

Presentism is not "incorporated in LET" as I again tried to explain before. Presentism is a philosophical view while LET is a scientific theory so the two are independent. Let's leave that topic for the philosophy forum.
...
It isn't. What I said was that if you assume presentism, you probably get LET but it doesn't follow the other way round. Anyway, let's leave presentism for the philosophy forum.

Firstly, it might be worth addressing the point about philosophy, just to get it out of the way, because it seems to be cropping up a bit.

Whether we like it or not, scientific theories have philosophical implications. Simultaneity is itself a concept, and insofar as we are discussing simultaneity, we are engaged in a philosophical discussion. Insofar as we are engaged in a discussion on RoS we are engaged in a philosophical conversation regarding Einsteinian relativity, which can help to expand our (the collective our, not necessarily you and me) understanding of relativity, and so it is perfectly suited to this section of the forum.

If we were to make no statement about the implications clock synchronisation has on simultaneity, then we wouldn't necessarily be discussing the philosophy of the theory; we could say that relatively moving clocks will not remain synchronised and leave it at that; that would be fine; but when we delve into a discussion about what this means for the simultaneity of events across reference frames, it becomes philosophical.


As for presentism being a part of LET, you mention above that it is not incorporated into LET, but earlier you mentioned

Effectively, LET is a consequence of assuming presentism. Lorentz was assuming Galilean Relativity which is equivalent.

This suggests that presentism is an assumption of LET, and therefore incorporated into it; just as the constancy of the speed of light is an assumption of Einsteinian relativity, and thus incorporated into it.


As you mention, Lorentz was assuming Galilean relativity, and I think it is correct to say that he assumed absolute space and time as Newton did, both of which incorporated, or have (or whatever the suitable verb is) the idea of a universal present moment i.e. presentism.

Indeed, but you have discussed nothing but LET's version of RoS and philosophy, there isn't a single comment related to relativity in anything you have posted.

The discussion relates to the necessary consequences of the Lorentz transform, an integral part of Einsteins theories. By expanding our (again, the collective) understanding of the necessary consequences of the LT, we (collective) expand our understanding of Einsteinian relativity.

Given that there are two theories which implement the LT, it is necessary to compare them and see what differences there are; only by doing so can we determine the necessary consequences of the LT, and thereby expand our understanding of Einsteinian relativity.

You have moved the presentism to the other forum so let's leave that there.

I presumed that people familiar with Newtonian physics would be familiar with the concept of presentism, or a universal present moment; but it appears as though I was mistaken. I started the thread there to try and get a more detailed explanation of it, in such a manner that it might benefit any discussions that refer to the concept; such as this one.

Bob doesn't exist, he's hypothetical. The LTs allow you to do the calculations.

They would also allow Bob to do them, if Bob was real.

Work through those definitions carefully, we went over this some time ago but you still seem to be having trouble with it. I've repeated the description above because it is key to the context.

It might be useful to go through it line by line, to see if there are places where I have misunderstood.

Think about the words. Two clocks are sychronised if their ticks are simultaneous.

No problem with this; it does require an assumption about the one way speed of light though doesn't it?

The time when an event occurs is defined by the reading on a clock local to the event.

This is true in Einsteinian relativity; I have no problem with this.

According to LET, however (which uses the lorentz transform and which it is being said also incorporates RoS) the time when an event occurs isn't defined by the reading on a clock local to the event; the time when an event occurs is defined by the reading on a clock in the preferred, absolute reference frame.

That means that two events are simultaneous if their times are the same as measured by synchronised clocks or, to put it another way, if their time coordinates are the same.

That is if we assume that the clocks are actually synchronised; something we can't actually verify; is that correct? LET doesn't assume the one way speed of light is constant, so how are clocks synchronised in that instance?


Note: that is an important issue in determining the necessary consequences of the Lorentz transform

 

[mangaroosh]

That is a non-sequitur as I clearly never said that. I stated that the condition of indeterminacy would be just as much a fact even if the universe was "actually" presentistic.

Apologies, I might have misunderstood the point you were making:

is RoS compatible with Presentism?
Einstein demonstrated that our idea of simultaneity was indeterminable.
That it was meaningless to say (or think) any two spatially separated events were simultaneous in any absolute sense. But this is just as true if this is a presentistic (?) universe.

SO yes, RoS, is as compatible with presentism as it is with block time, as both are essentially philosophical or metaphysical concepts and questions.

It seemed as though you were saying that presentism is just as indeterminable as Ros, "so" [therefore] RoS is "compatible with presentism"; also, that "as both are essentially philosophical or metaphysical concepts and questions" they are [therefore] compatible.

That, of course, would be a non-sequitir,.

yes I cannot rule out the possibility that the universe is presentistic but that in no way suggests that RoS is indeterminable as it simply deals with what IS determinable i.e. Empirical measurements and observations; CLOCKS

The definition of RoS that has been provided by others, in this thread, extends RoS beyond simple synchronisation of clocks; it includes it, and is entirely based on it, but it extends it beyond that.

My understanding of RoS is that events which are simultaneous in one reference frame are not necessarily simultaneous in other reference frames i.e. if two events are not simultaneous in one reference frame it is possible that they are simultaneous in other reference frames. Is that accurate to any degree?

Yes.

If that is an accurate description of RoS, or its consequences, then it isn't compatible with presentism, because it means that there is no universal present moment.

At the risk of being redundant; the source of much of your confusion and difficulty in understanding what everybody has been telling you is that you are continually mixing apples and oranges.

Presentism and Block Time are philosophies.
These concepts ARE NOT compatible

SR and LET are scientific theories.
AS theories that that make the same empirical predictions they ARE compatible.

Does this mean that LET is equally as valid as Einsteinian relativity; why are they not the exact same theory?

They are scientific theories which offer different explanations for those empirical predictions; explanations which are not necessarily compatible.

It's a bit like saying there is a theory of the universe which says that Gargamoyl the great created the universe in 16hrs, and continues to influence it; and there is also a theory which says that the universe wasn't created by Gargamoyl, and that he doesn't influence it. Both make the same empirical predictions, but both offer entirely different explanations as to why. Both theories are not necessarily compatible.

Some LETists are Presentists and some Relativitists are Block Timers but this is completely irrelevant to the Theories themselves.
Philosophically Newton was an Absolutist but as a scientist he was as much of a Relativitist as Einstein. The theories had no element of absolutism.

Are there any LETists who are Block timers, and are there any relativists who are presentists? That is the critical question.

Newton was a presentist; was Einstein?

Right.

WRONG. RoS says absolutely nothing about a present moment or whether or not a universal present moment actually exists. It simply correlates proper time readings in differing
inertial frames.
Once again you are confusing two different interpretations of simultaneous.
RoS is the idea that the proper time reading is relative for each observer.
You are free to interpret this however you choose. Eg; There is a universal now and the clocks are all incorrectly desynchronized according to the universal instant.
RoS is not incompatible with that interpretation , it is merely irrelevant.

There is no confusion as to the meaning of the term simultaneous.

Again, the definition of RoS, that has been agreed on by Dale and Harry goes beyond the simple clock synchronisation, although it is based on it.

Where RoS refers to the idea that simultaneous events in one reference frame are non-simultaneous in another, this means that there is no universal present moment, and thus it would not be compatible with presentism.

No; block time and presentism are unverifiable

But block time is neither a necessary condition for , nor an inevitable logical derivation from RoS
They are mutually independent. But you seem to keep trying find a necessary correspondence and insisting there is one.

Again, the definition of RoS, that Harry and Dale agreed upon, refers to mutually simultaneous and non-simultaneous events. The simultaneity of events is indeterminable, meaning that, if that definition is accurte, or representative, then RoS is indeterminable.

 

[GeorgeDishman]

Just a quick note:

As for presentism being a part of LET, you mention above that it is not incorporated into LET, but earlier you mentioned

Effectively, LET is a consequence of assuming presentism. Lorentz was assuming Galilean Relativity which is equivalent.

This suggests that presentism is an assumption of LET, and therefore incorporated into it; ...

"Affirming the consequent":

http://en.wikipedia.org/wiki/Affirming_the_consequent

Presentism implies LET.

LET does not imply presentism.

(NB the first is also arguable.)

Or try it as two statements. In LET, I would argue the first is a valid logical deduction but the second isn't:

1) If only the present exists, then the Twins Paradox shows that clocks are affected by motion.

2) If clocks are affected by motion as shown by the Twins Paradox, then only the present can exist.

 

[mangaroosh]

Just a quick note:
"Affirming the consequent":

http://en.wikipedia.org/wiki/Affirming_the_consequent

Presentism implies LET.

LET does not imply presentism.

(NB the first is also arguable.)

Or try it as two statements. In LET, I would argue the first is a valid logical deduction but the second isn't:

1) If only the present exists, then the Twins Paradox shows that clocks are affected by motion.

2) If clocks are affected by motion as shown by the Twins Paradox, then only the present can exist.

If assuming presentism leads to LET;
and RoS implies the absence of a universal present (or not-presentism);
while presentism implies the existence of one (or not-RoS);
then LET cannot be compatible with RoS.

EDIT: unless LET can be arrived at without presentism; either way, it would demonstrate that RoS - as per the definition agreed upon by Harry and Dale - is not a necessary consequence of the loretnz transform.

 

[GeorgeDishman]

"Affirming the consequent":

http://en.wikipedia.org/wiki/Affirming_the_consequent

Presentism implies LET.

LET does not imply presentism.

(NB the first is also arguable.)

Or try it as two statements. In LET, I would argue the first is a valid logical deduction but the second isn't:

1) If only the present exists, then the Twins Paradox shows that clocks are affected by motion.

2) If clocks are affected by motion as shown by the Twins Paradox, then only the present can exist.

If assuming presentism leads to LET;

That is quite possible (though I admit arguable).

and RoS implies the absence of a universal present (or not-presentism);

It does not, RoS is an observation regarding the synchronising of clocks.

while presentism implies the existence of one

Presentism doesn't imply it, it assumes it, and it is rather the rejection of the existence of anything other than the present (which may be different).

(or not-RoS);

No, RoS is an observation regarding the synchronising of clocks, it is not a philosophy.

then LET cannot be compatible with RoS.

EDIT: unless LET can be arrived at without presentism; either way, it would demonstrate that RoS - as per the definition agreed upon by Harry and Dale - is not a necessary consequence of the loretnz transform.

The definition of simultaneity you quote below as having been agreed is:

My understanding of RoS is that events which are simultaneous in one reference frame are not necessarily simultaneous in other reference frames i.e. if two events are not simultaneous in one reference frame it is possible that they are simultaneous in other reference frames.

I too agree that explanation of RoS. Where you are wrong is when you say:

There is no confusion as to the meaning of the term simultaneous.

1) Simultaneous means "At the same time".

2) Time is what a clock reads.

Therefore

3) Simultaneous means "At the same time coordinate as measured by synchronised clocks."

4) Since "synchronised" is frame dependent, the definition of RoS you give above follows.

5) If "synchronised" were not frame dependent, the definition of "simultaneous" would be independent of the frame and RoS would not exist, we would not be having this conversation.

 

[harrylin]

No, crudely, presentism is the philosophy that things that exist are 3-dimensional and that time is an emergent property resulting from the perception of change. It contrasts with eternalism which considers that the past, present and future existence of entities are equally real. [..].

Just a last remark about such philosophical words:
Your "no" implies that presentism is at odds with the "true time" concept. However, "true time" certainly contrasts with the eternalism of the block universe philosophy, and fits with the view of the world as a three-dimensional space that is modulated by the passage of time.
- http://en.wikipedia.org/wiki/Eternalism_(philosophy_of_time)

 

[harrylin]

[..]it would demonstrate that RoS - as per the definition agreed upon by Harry and Dale - is not a necessary consequence of the loretnz transform.

That's a self contradiction, as we stressed many times already. Apparently you never derived this fact yourself, perhaps because you find the equation too complex. Never mind I can simplify it for you. Here is the older, pre-SR Lorentz transformation for time - and it is roughly the same as the modern one for low velocities:

t'= t - x*v/c^2

If you fill in some values you can only find that for a single time t of system S everywhere, the time t' of system S' depends on the x position in S.
Consequently, what is simultaneously (at time t) happening at different x according to S, happens at different times t' according to S'.
Please explain with a numeric example how you think that this result can be avoided.

 

[GeorgeDishman]

Just a last remark about such philosophical words:
Your "no" implies that presentism is at odds with the "true time" concept. However, "true time" certainly contrasts with the eternalism of the block universe philosophy, and fits with the view of the world as a three-dimensional space that is modulated by the passage of time.

It's more subtle than that, eternalism as you say is at odds with presentism and is often associated with the block universe model, but you can apply presentism to the block universe to get either the Growing Block model or the Moving Spotlight model.

Equating presentism with the concepts of absolute time as 'mangaroosh' did is inaccurate and misleading so I hoped I could clarify it before it became seen as an accepted definition within the thread.

 

[Dale]

Presentism refers to the idea that there is a single, universal present moment, common to all observers.

I see that you prefer to dodge the question which I have twice repeated and put in bold so that you could not miss it and instead preferred to simply repeat the very thing that I was asking clarification about (never an effective method of clarification).

Since I prefer to be up front and clear I will simply assume what I think is your most likely answer to my question for clarification and then answer your simple yes or no questions accordingly. If you don't like the answers, then feel free to actually answer the request for clarification.

"What are the experimental consequences of presentism, or is it merely a philosophical viewpoint?"

My best guess for your answer: there are no experimental consesquences, it is merely a philosophical viewpoint.

Firstly, is RoS compatible with Presentism i.e. the idea that there is one, universal present?

Yes. Presentism, as a philosophical viewpoint with no experimental consequences is inherently compatible with all experimental observations.

Secondly, is prensentism incorporated in LET?

LET is certainly compatible with the philosophical viewpoint of presentism, but I don't know if Lorentz explicitly incorporated it in any of his writings. I suspect not, but have no references to provide on the topic either way.

 

[Dale]

just wondering if you guys are familiar with Newtonian physics; am I right in saying that Newton's theory incorporated absolute space and time, as well as the idea of a single, universal present moment?

He definitely wrote specifically about absolute space and time, but I don't recall any of his writings specifically about the present. However, as philosophical viewpoints with no experimental consequences, presentism and alternatives, are all compatible with Newtonian mechanics also.

 

[Dale]

My understanding of RoS is that events which are simultaneous in one reference frame are not necessarily simultaneous in other reference frames i.e. if two events are not simultaneous in one reference frame it is possible that they are simultaneous in other reference frames. Is that accurate to any degree?

Yes.

If that is an accurate description of RoS, or its consequences, then it isn't compatible with presentism, because it means that there is no universal present moment.

That is not implied. As we have discussed multiple times at length and in great and exhaustive detail, simultaneous simply means that they have the same time coordinate. So this definition says that given two reference frames and two events it is possible that one referernce frame assigns the two events the same time coordinate and the other assigns them different time coordinates.

It says nothing whatsoever about whether those time coordinates are in the past, present, or future, or even whether or not there is any distinction between past, present, and future.

 

[mangaroosh]

It is probably worth establishing something from the outset:

If two events are simultaneous in the universal present, then they are simultaneous for all observers everywhere, across all reference frames. Regardless of the readings of any clocks.

If RoS allows for events to be simultaneous in one reference frame and non-simultaneous in another, then it is not compatible with presentism.

This holds true regardless of clock synchronisation.


We can define simultaneity without any reference to time keeping devices, and therefore any philosophical assumptions about them and the nature of time, by stating that two events are simultaneous if, while one event is happening, the other event is also happening.

We may not be able to measure this, without a synchronisation convention, but when our synchronisation convention relies on an unmeasurable, or untestable assumption, it fares no better.

That is quite possible (though I admit arguable).

I think the fact that LET employs a Newtonian concept of time and space implies that it is a presentist theory. Is it possible that the Newtonian concept of space and time could lead to a non-presentist theory?

It does not, RoS is an observation regarding the synchronising of clocks.

Again, if RoS allows for events to be simultaneous in one reference frame, and non-simultaneous in another, then it is incompatible with the idea of a universal present, and therefore presentism.

Presentism doesn't imply it, it assumes it, and it is rather the rejection of the existence of anything other than the present (which may be different).

The term presentism implies the existence of a universal present, was what I meant; it's what the term means.

I don't think the second formalism materially changes it.

No, RoS is an observation regarding the synchronising of clocks, it is not a philosophy.

The synchronisation convention is based on an unverifiable assumption, the one-way speed of light, isn't it? If it is then the synchronisation convention is, itself, a philosophical proposition.

Simultnaeity of events is, itself, a philosophical proposition. If it cannot be determined that events are absolutely simultaneous, then it implies that it is possible that they might be; this means that it cannot be verified that events are simultaneous in one reference frame and non-simultaneous in another; that means RoS is not verifiable, and is therefore a philosophical proposition.

I too agree that explanation of RoS. Where you are wrong is when you say:

There is no confusion as to the meaning of the term simultaneous.

The confusion doesn't so much lie in the idea of simultaneity, rather the concept of "at the same time".

Simultaneity can be expressed, without confusion, as, when one event is happening the other event is also happening. For example, if we take the clapping of our hands; our hand claps are simultaneous if, when my two hands meet , your two hands also meet.

The question arises when we add the qualifier, "at the same time".

1) Simultaneous means "At the same time".

2) Time is what a clock reads.

Therefore

3) Simultaneous means "At the same time coordinate as measured by synchronised clocks."

4) Since "synchronised" is frame dependent, the definition of RoS you give above follows.

5) If "synchronised" were not frame dependent, the definition of "simultaneous" would be independent of the frame and RoS would not exist, we would not be having this conversation.

The issue might lie in the assumption of synchronisation, and the synchronisation convention.

I'm just wondering does such a synchronisation convention exists in LET, given that the assumption about the one-way speed of light isn't incorporated?

 

[GeorgeDishman]

I understand that RoS relates to the synchronisation of clocks, in Einsteinian relativity, at least.

That is the key to understanding the question. The phrase "relativity of simultaneity" was coined specifically in the context of SR hence that is its only defined meaning. You can resolve your doubt by noting that in SR there is no other type of time other than "what a clock reads" and hence the phrase can have only one meaning.

Now certainly, once you have the phrase, you can retrospectively apply it to the same observed behaviour in LET but since LET is then borrowing the phrase, it doesn't change the meaning. In LET as others have already pointed out, the equivalent is what Lorentz called "local time". If you want it to have an alternative meaning, you are re-inventing the term.

The question is whether or not it relates purely to the synchronisation of clocks - please don't simply reply with "it does" here, because I am trying to outline my understanding of why it might not; if it does, then it would apply equally to LET.

Again, there you have your answer. Since RoS is a phrase from SR where it can only apply to clocks, it can apply equally to LET.

That the clock synchronisation method relies on an untestable assumption i.e. the one way speed of light, makes it a philosophical consideration, not an experimentally verifiable one.

No, the technique of bouncing the light back to the source relies only on the fact that the measured speed is isotropic which is a consequence of the Lorentz Transforms and therefore also valid in LET. What isn't testable is LET's extraneous concept of some other form of time, but clock synchronisation in LET refes to "local time" for practical scientific measurement (it is local time values that go into the variables in the transforms obviously, you can't use numbers that are impossible to measure).

Firstly, it might be worth addressing the point about philosophy, just to get it out of the way, because it seems to be cropping up a bit.

Whether we like it or not, scientific theories have philosophical implications.

Science very often has implication for philosophy but seldom vice versa. Science is predicated on discerning knowledge only from objectively verifiable data so only uses philosophy as a last resort.

Simultaneity is itself a concept, and insofar as we are discussing simultaneity, we are engaged in a philosophical discussion.

Two adjacent clocks are synchronised if the tick simultaneously, that is something that can be determined physically without any philosophical input.

Insofar as we are engaged in a discussion on RoS we are engaged in a philosophical conversation regarding Einsteinian relativity,

No, you have only ever discussed the relationship between the philosophy of LET and presentism, not a word about SR. To be honest, I get the impression that you have no knowledge of SR whatsoever but that may simply have been due to the very narrow nature of the conversation.

If we were to make no statement about the implications clock synchronisation has on simultaneity, then we wouldn't necessarily be discussing the philosophy of the theory; we could say that relatively moving clocks will not remain synchronised and leave it at that; that would be fine; but when we delve into a discussion about what this means for the simultaneity of events across reference frames, it becomes philosophical.

Again you are failing to consider the language, two clocks are "synchronised" if they show the same time values "simultaneously".

As you mention, Lorentz was assuming Galilean relativity, and I think it is correct to say that he assumed absolute space and time as Newton did, ..

I don't know whether he did or not but if so, he could potentially have had three different times in his philosophy since the aether might have been dragged. I've never heard of that in LET so I suspect he didn't.

The discussion relates to the necessary consequences of the Lorentz transform, an integral part of Einsteins theories. By expanding our (again, the collective) understanding of the necessary consequences of the LT, we (collective) expand our understanding of Einsteinian relativity.

No, you are becoming so blinkered and focussed on LET, I doubt you will ever be able to learn the basics of SR.

I presumed that people familiar with Newtonian physics would be familiar with the concept of presentism, or a universal present moment; but it appears as though I was mistaken.

They will be familiar with Newton's "absolute time" from the Scholium but may not have studied philosophy so may not know presentism.

They would also allow Bob to do them, if Bob was real.

You seem determined to miss the point at any cost.

Consider an observer, Alice, who has a long rigid pole with a clock at each end, A and B. She uses some practical physical technique to synchronise the clocks, for example by sending a light pulse from A to B where it is immediately reflected back to A. If the time of the pulse being reflected at B is midway between the send and receive times at A, the clocks are defined as being synchronised. A second observer, Bob, traveling past this setup who uses the same technique determines that the clocks are not synchronised. The determination is therefore related to the motion of the observer. That is called the relativity of simultaneity.

1) Can you see that the Lorentz Transforms can be used to calculate by how much Bob will consider the clocks to differ from being synchronised?

2) Can you see that the above scientific definition of synchronisation is independent of any philosophical musing on the nature of time?

Work through those definitions carefully, we went over this some time ago but you still seem to be having trouble with it. I've repeated the description above because it is key to the context.

It might be useful to go through it line by line, to see if there are places where I have misunderstood.

I've repeated it again for your convenience, by all means query any sentence where you have a concern.

Think about the words. Two clocks are sychronised if their ticks are simultaneous.

No problem with this; it does require an assumption about the one way speed of light though doesn't it?

No, look at the sentence, it is only a definition of what we mean by the word "sychronised", it says nothing about any proposed method for achieving the sychronisation of clocks.

The time when an event occurs is defined by the reading on a clock local to the event.

This is true in Einsteinian relativity; I have no problem with this.

According to LET, however (which uses the lorentz transform and which it is being said also incorporates RoS) the time when an event occurs isn't defined by the reading on a clock local to the event; the time when an event occurs is defined by the reading on a clock in the preferred, absolute reference frame.

No. The LTs convert between two frames, say A and B. In theory, if you knew the speed of A and B relative to the aether frame E, you could take "local times" (clock values) in A, use the LTs backwards (they are symmetrical though) to convert to "true times" in E, then apply them forwards to convert from E to clock times in B. However, the nature of the equations is such that if you use the speed of B relative to A and apply them just once, you convert local times in A to local times in B, the philosophical aether times are irrelevant. In order to use the LTs in any practical experimen, you can only use local times. Since the RoS is a result you see in applying the transforms, the RoS applies to clock times in LET.

That is if we assume that the clocks are actually synchronised; something we can't actually verify; is that correct?.

No, the times that go into the LTs are clock times. You can use them to convert from any frame directly to any other frame without any consideration of philosophical aspects. Two clocks are therefore "actually synchronised" if they show the same reading at the same time coordinate.

LET doesn't assume the one way speed of light is constant, so how are clocks synchronised in that instance?

The same way as in SR. The LTs mean that the measured speed of light is isotropic (one way equals two way) and science only concerns itself with measurables.

Note: that is an important issue in determining the necessary consequences of the Lorentz transform

No, it is totally irrelevant since the LTs work directly from any frame to any other, you do not need to do double conversions via the aether frame. As a result, the consequences of the LTs are independent of the existence of any hypothetical aether.

That is also why Ockham's Razor suggests we discard the aether concept and hence discard LET in favour of SR.

 

[mangaroosh]

I see that you prefer to dodge the question which I have twice repeated and put in bold so that you could not miss it and instead preferred to simply repeat the very thing that I was asking clarification about (never an effective method of clarification).

Since I prefer to be up front and clear I will simply assume what I think is your most likely answer to my question for clarification and then answer your simple yes or no questions accordingly. If you don't like the answers, then feel free to actually answer the request for clarification.

"What are the experimental consequences of presentism, or is it merely a philosophical viewpoint?"

My best guess for your answer: there are no experimental consesquences, it is merely a philosophical viewpoint.

I wasn't sure of the answer, as to what the experimental consequences of presentism are, so I simply asked for your opinion as to whether or not you agreed that the two concepts, as presented, were incompatible. If I accurately represneted both concepts, and we agreeed they were incompatible, then that would have offered another means of resolving the issue - and of course, it remains one.

The question also remains as to whether RoS is a philosophical interpretation of clock synchronisation; insofar as RoS refers to events which are simultaneous in one reference frame being non-simultnaeous in another, it is not compatible with the concept of presentism provided. If LET is compatible with that concept of presentism, then it suggests that RoS cannot be a necessary consequence of the LT, because RoS is not compatible with presentism.

So, the question of presentism being a philsophical viewpoint does not resolve the issue, because RoS is arguably a philopsophical viewpoint also - regardless of the assertions to the contrary.

The question of whether or not presentism is compatible with, or incorporated into, LET would help to resolve the issue. Insofar as LET is based on Newtonian, or Galielan time and space, then it suggests that LET does not allow for events that are simultaneous in one reference frame to be non-simultaneous in another.

Yes. Presentism, as a philosophical viewpoint with no experimental consequences is inherently compatible with all experimental observations.

I think it would have experimental consequences, similar in nature to the Principle of Relativity; I probably risk an infraction by stating what they are though, as I suspect it might be classified as a personal theory. I would probably need express permission to do so.

LET is certainly compatible with the philosophical viewpoint of presentism, but I don't know if Lorentz explicitly incorporated it in any of his writings. I suspect not, but have no references to provide on the topic either way.

Is RoS compatible with Newtonian physics, and Galilean relativity?

It's been mentioned that LET is essentially based on the Newtonian concepts of time and space, and Galilean relativity. If that is correct, and RoS is not compatible with those, then it probably means that RoS is not compatible with LET, I would think.

He definitely wrote specifically about absolute space and time, but I don't recall any of his writings specifically about the present. However, as philosophical viewpoints with no experimental consequences, presentism and alternatives, are all compatible with Newtonian mechanics also.

I think presentism is something which can be extrapolated from the theory. Presentism, possibilism and eternalism

It might be worth asking if Newtonian mechanics allowed for RoS, or did it incorporate the idea of a universally shared present moment?

That is not implied. As we have discussed multiple times at length and in great and exhaustive detail, simultaneous simply means that they have the same time coordinate. So this definition says that given two reference frames and two events it is possible that one referernce frame assigns the two events the same time coordinate and the other assigns them different time coordinates.

It says nothing whatsoever about whether those time coordinates are in the past, present, or future, or even whether or not there is any distinction between past, present, and future.

We can extrapolate it though, based on that.

If there is a universal present moment, then events which are simultaneous in the universal present, are simultaneous for all observers; that is, they are simultaneous in my present, and in your present, and we share the same present moment.

RoS is not compatible with that.

 

[GeorgeDishman]

It is probably worth establishing something from the outset:

If two events are simultaneous in the universal present, then they are simultaneous for all observers everywhere, across all reference frames.

You are muddling up several different concepts. The "universal present" is a philosophical concept of no concern to this discussion.

In Newtonian theory, he defined the concept of "absolute time". If two events were simultaneous in Newton's universe, they would be judged to be simultaneous by all observers because clock synchronisation would be independent of speed. However, the universe doesn't work that way.

In LET, if two events are judged to be simultaneous in the local aether rest frame, they will not be judged to be simultaneous by any observer moving relative to the aether in the direction of the line joining the events.

In SR, if a line between two events is perpendicular to one observer's worldline, it cannot be perpendicular to that of another observer moving relative to the first observer in the direction of the line joining the events.

Regardless of the readings of any clocks.

"Simultaneous" is a statement about clock readings in Newtonian physics, LET and SR. If you want to apply some other meaning, you need to be posting in the philosophy forum.

If RoS allows for events to be simultaneous in one reference frame and non-simultaneous in another, then it is not compatible with presentism.

Generally, most scientists would agree that presentism is untenable but there are a few die-hard philosophers still trying to find a way of keeping it.

We can define simultaneity without any reference to time keeping devices ..

Not in LET, SR or the Newtonian model. All of physics is about relationships between measurements.

Is it possible that the Newtonian concept of space and time could lead to a non-presentist theory?

Yes, as I said before, it would be compatible with the block universe. In fact Newton was concerned that that was the case as it had implications for free will.

Again, if RoS allows for events to be simultaneous in one reference frame, and non-simultaneous in another, then it is incompatible with the idea of a universal present, and therefore presentism.

There's no point repeating something when I have already explained several times why it is not true. Try to move on.

The term presentism implies the existence of a universal present, was what I meant; it's what the term means.

It's not what the term means to several decades of professional philosophers, I have given you reliable sources such as the Stanford Encyclopedia where your can see clear definitions of these terms. You are not helping the discussion by trying to invent alternative meanings, especially since you haven't done any work to ensure they are usable. The philosophical community has and those terms are well defined.

I don't think the second formalism materially changes it.

Then you should have no reason not to use the accepted definition.

The synchronisation convention is based on an unverifiable assumption, the one-way speed of light, isn't it?

No, it is based on the well proven knowledge that the measured speed is isotropic in both LET and SR.

I'm just wondering does such a synchronisation convention exists in LET, given that the assumption about the one-way speed of light isn't incorporated?

The practical lab techniques for synchronising clocks were the same regardless. Nothing other than clock times went into the LTs so Lorentz needed nothing more.