# Models for making sense of relativity - physical space vs physical spacetime

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You asked what are models to describe physical space with spacetime. Where is the hijack ????

All I've seen you do is make declarations and post links that don't describe what your after. Neither Block nor ether is needed to describe the title of this thread.

You wish to examine models You obviously have no clue of what is involved in them but you want to use them to teach relativity?????

You asked several times to show how EFE describes the time dilation, length contraction aspects. I provided that. In doing so I showed you do not require neither Ether nor block universe to understand relativity.

Now it is your turn Prove me wrong.

-- This is a spin-off of the thread "is space-time a physical entity [..]" --

A lot of people think that special relativity doesn't make sense and that it's hopeless to try to understand it; we are condemned to "shut up and calculate". However, I know of two physical models that can be used to explain the theoretical predictions, and possibly there is another model that I don't know of.

: To be perfectly clear, with "physical models" I here mean two competing hypothetical physical entities that have been proposed to make sense of the phenomena as described by relativity theory.

direct quote from the OP....... I provided a third.

Edited by Mordred

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You asked what are models to describe physical space with spacetime. Where is the hijack ????

All I've seen you do is make declarations and post links that don't describe what your after. Neither Block nor ether is needed to describe the title of this thread.

You wish to examine models You obviously have no clue of what is involved in them but you want to use them to teach relativity?????

You asked several times to show how EFE describes the time dilation, length contraction aspects. I provided that. In doing so I showed you do not require neither Ether nor block universe to understand relativity.

I did not ask what are models to describe physical space with spacetime, nor did I ask to show how equations describe time dilation. Everyone who participates with me on explaining models of reality of SR is assumed to understand at least the mathematics of SR.

Sorry for calling it hijacking, but it effectively was like hijacking, because you never understood the topic, nor my questions, only accidentally now and then being on topic. I wonder, did you actually understand the topic of the mother thread on spacetime from which this is a spin-off??

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You declared you know of two models to help explain the math of SR. You haven't shown how instead you expect us to. See the quote above, sorry I can read....

go ahead try to use Block to explain the math of SR.

1) first convert all metrics to the corresponding Hamiltons and action.

2) then apply the Block universe equation to reduce those to deterministic statistics.

Lorentz Ether. The only way to make sense to use this is to call fields ether. Why not just use the fields in the first place.

When you teach SR you must be prepared for whatever analysis the questioner asks pertaining to a model. Including the math.

Can you perform the math in block? if not don't use it.

Can you show where Lorentz ether makes a difference if not don't use it.

pretty simple

. Everyone who participates with me on explaining models of reality of SR is assumed to understand at least the mathematics of SR.

You can't assume that, the purpose is to explain why those equations work if needed, explain how they are derived. Neither Block nor Lorentz ether is needed to explain the Reality involved in SR. You can point to the properties you can determine. Quite frankly if people can't understand perspective due to spatial separation or time dilation. I don't see how block or Lorentz ether will help you.

A good course in differential geometry may be better suited lol

Anyways in SR one can argue invariant quantites are more real than variant. Invariant naturally are determinant. Variant is potentially but not in all cases.

I can easily keep posting processes where it would be extremely difficult to fall under Block.

I cannot describe or name any process that can't fit under evolving block.

Using Lorentz ether which is questionable if it exists or not to describe reality.

Sorry I fail to see the logic in that approach

Edited by Mordred
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Perhaps only an illustration can help.

In a discussion group on an isolated island where nobody smokes, the topic is discussed "is this not a pipe?" by a member who has seen a painting of a pipe - https://en.wikipedia.org/wiki/The_Treachery_of_Images

In the course of a very long discussion, the consensus is reached that there must be more to it: there must be a real, three dimensional pipe in order to enable smoke to come out of its orifice. One member therefore starts a "spin-off" of the generic "mother" discussion to compare two proposed real pipe models which compete in explaining the creation of the smoke, one with a duct along the length, the other with just a cavity. He refers to the original discussion and emphasizes that redoing the "mother" discussion in the "spin-off" discussion would be sabotage as that is off-topic, while it's of course welcome in the original discussion which is still taking place in parallel.

Then the discussion of the pipe models is joined by a group member who says that although he prefers a variant of model two, neither model passes scrutiny. He even has a better model. The other group members listen with great expectation. He then picks up a ballpoint and creates with great care and much devotion a beautiful drawing of a pipe with smoke coming out of it. "Look here", he says; "A model is a description. The moment that you are starting to paint a pipe, you are painting a description; you can just as well use a pen. No paint, no duct, no cavity. Duct and cavity models are totally useless, they can do nothing. Useless to include it in the description of Reality." He ends with stressing the importance of taking drawing lessons.

Edited by Tim88
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I think you don't fully understand block universe/expanded block universe.

Neither of the above add anything to the SR metrics. Those two models don't add anything to any metric. QM, classical or otherwise.

All processes that can be modelled as reversible fit under block. If you can't model it as reversible you have the evolving block.

Neither model above adds any dynamic to GR/SR etc.

Lorentz Ether however is a different matter. It adds a hidden background medium. One that is unnecessary as it has no measurable influence.

So if you wish to use block or evolving block go right ahead. There is no questionable dynamic added to any time dilation formula. It doesn't try to add any dynamics to any formula.

Its simply a philisophical classification of time with events.

I don't have any objections on block/evolving block. Provided they are used correctly. (reversible/irreversible)

Fundamentally all it does it ask the question. "Can all processes be accurately modelled as deterministic,"

Evolving block tries to keep events as deterministic as possible.

Nothing more....

Although I agree with a lot of what Mordred posted in the part quoted above, I do have a few reservations. This is not necessarily to counter- or question Mordred, but an attempt to share the visualisation of this model. As far as I am concerned the standard block universe is generally perceived as both deterministic and eternalistic (although there are arguments favouring presentism and indeterminism). In another thread studiot and myself were, at first, unable to find common ground re the block universe until we resolved a simple misunderstanding re the term deterministic. So before we proceed, let us revisit said term and its intended definition i.t.o. the block universe: A deterministic system is a system in which no randomness is involved in the development of future states of the system. A deterministic model will thus always produce the same output from a given starting condition or initial state. It is important to understand that the (deterministic and eternalistic) standard block universe proposes immutable past, present and future events (fixed in stone, done and dusted). One has to actually visualise a "physical" (granular, particle, or field-assembled) eternal horizontal block; with no beginning and no end (if you want to, add an infinitely expanding shape). This eternal (on-its-side-cone-shaped) block is made up with an infinite (yes I know, another topic for another discussion) number of vertically aligned slices, each with its own immutable event. Embedded into this block (say from left to right along its expanding shape) is our "chronological" perception of these events (aka our sense of reality). Each "consecutive" slice will yield an immutable future event that will be perceived as "qualia", i.e. experiencing or observing an event on a specific coordinate (opposed to a moment in time) within this four-dimensional block. No doubt that there are physical processes (both on quantum and on macro level) transpiring in the unfolding of each event...but these processes are predetermined...immutable. They may appear random or uncertain, yet they simply "manifest as they should have" in order to illuminate (as per the moving spotlight) the next event. Let us consider that film analogy as described in the source that I referenced earlier in the thread where our embedded perception of reality within this block universe equates to a film consisting of countless frames, each frame consisting of a separate mini process towards an inevitable future. Our perception thereof is akin to watching the movie where everything occur in a sensible, chronological and natural manner...waiting for events to unfold. Imagine having an alternative manner of accessing said reality, like the ability to pause, rewind or even fast forward...for example a scene where a car falls from a cliff that can be paused, or rewind...as if violating the laws of physics..?

Which brings me to the evolving block. I find it hard to buy into the notion that "evolving block tries to keep events as deterministic as possible" given the above explanation and illustration. Let me also add another- and slightly different perspective, an opinion that I find quite appealing:

Registry and Evolving Block Universe

The block view and the time evolution view are not as incompatible as they may look at a first sight. We can recover the time evolution by watching the entropy distribution between the events of the block world, and the causal co-relations between them. I would like to compare the registry time evolution with the Evolving Block Universe of George Ellis. Professor Ellis proposes an evolving block universe, perhaps the most credible proposed so far. He explains that the quantum phenomena (in the standard indeterministic interpretation of QM) should have gravitational effects. Consequently, they must change the spacetime. I agree with this argument. Further, he details a theory in which the time flows, evolves, in a sort of presentist way, and the past, which already happened, is “archived” in a block universe. The block universe increases with time, as new “presents” adds to it. The future is not decided yet, and as it happens, it becomes present, and then it is archived. This view is well elaborated, and reflects well our feelings of time flow, free-will, carved in stone past, and open future. On the other hand, I do not agree with Professor Ellis that QM proves the indeterminism. Even so, assuming the indeterminism valid, this doesn’t eliminate the possibility of the standard block view.

Perhaps the most important difficulty of such an Evolving Block Universe is the possibility, offered by QM, of deciding the past events chronologically after they took place. This implies that we have to wait to archive the passed times. Moreover, it is possible to never be able to determine the past completely. Consider Wheeler’s delayed choice experiment, with the photon emitted by a distant star. The observer watching the star will decide whether to measure the “both ways”, or the “which way”. Her decision affects the past history of the observed photon, hence of the observed star. Of course, it is unlikely that she affected the star’s state in a significant way, but she affected it at least in a small way. Until the observation, the photon, hence the star (by entanglement), was in an undefined state. Assume now that the photon is never observed, and escapes far from any planet and any possible observer. The Universe will remain in an undetermined state. So, we cannot say that the past block will be ever created. On the other hand, my proposal of a “registry” of incomplete initial data which increases with each observation, relying on Smooth Quantum Mechanics, allows the possibility that the state of the Universe remains undetermined. Professor’s Ellis idea of foliating the spacetime so that the spacelike surfaces contains the wavefunction collapses may be unreachable, because the entanglement makes the collapses impossible to be ordered temporally. I am afraid that the entanglement can be complicated enough. The measurements of the spins of the two electrons in the EPR-B experiment can be in any spacetime relation. We cannot consider that the wavefunction collapse takes place necessarily along such preferred spacelike surfaces, which are compatible with a spacetime foliation. It is easy to see that, if we associate spacelike surfaces to the collapse, it is possible that these intersect in complicated ways. Moreover, collapse can take place also between events that cannot belong to the same spacelike surface, being for example one in the other’s future.

The standard BU attempts to express the temporal structures in terms of timeless structures. We can consider it, in a way, as a research program of explaining the time itself in terms of timeless structures. But, by adhering to a presentist view, and by reducing the BU functionality to a purely archiving role, there is the danger of explaining the time by appealing to time in a circular way: the EBU includes the passed time in the archived BU, but the evolution happens in a metatime. Another interesting feature the BU has is that it contains all the physical fields in its description. By giving a special role to the present, we introduce a feature which has no correspondent in the matter fields. The BU accounts for the physical fields, but it cannot include an intrinsic present, and maybe doesn’t even need. Yet, if it would need to mark the present, a “BU with a bookmark” would solve the problem.

The registry view is compatible with both time evolution, and with the standard block universe view. And it shares with the EBU picture the compatibility with our feelings of time flow, free-will, open future, but not the carved in stone past.​

Lastly and simply as a matter of interest: There seems to be a compelling parallel with another thread in the Biology/Evolution section that deals with free will, consciousness and evolution: http://www.scienceforums.net/topic/74370-since-we-have-no-free-will-what-purpose-doesdid-consciousness-serve/

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[..] the (deterministic and eternalistic) standard block universe proposes immutable past, present and future events (fixed in stone, done and dusted). One has to actually visualise a "physical" (granular, particle, or field-assembled) eternal horizontal block; with no beginning and no end (if you want to, add an infinitely expanding shape). This eternal (on-its-side-cone-shaped) block is made up with an infinite (yes I know, another topic for another discussion) number of vertically aligned slices, each with its own immutable event. Embedded into this block (say from left to right along its expanding shape) is our "chronological" perception of these events (aka our sense of reality). Each "consecutive" slice will yield an immutable future event that will be perceived as "qualia", i.e. experiencing or observing an event on a specific coordinate (opposed to a moment in time) within this four-dimensional block. No doubt that there are physical processes (both on quantum and on macro level) transpiring in the unfolding of each event...but these processes are predetermined...immutable[..]

Which brings me to the evolving block. I find it hard to buy into the notion that "evolving block tries to keep events as deterministic as possible" given the above explanation and illustration. Let me also add another- and slightly different perspective, an opinion that I find quite appealing:

[The block view and the time evolution view are not as incompatible as they may look at a first sight. We can recover the time evolution by watching the entropy distribution between the events of the block world, and the causal co-relations between them. ¨[..]

The standard BU attempts to express the temporal structures in terms of timeless structures. We can consider it, in a way, as a research program of explaining the time itself in terms of timeless structures. But, by adhering to a presentist view, and by reducing the BU functionality to a purely archiving role, there is the danger of explaining the time by appealing to time in a circular way: the EBU includes the passed time in the archived BU, but the evolution happens in a metatime. Another interesting feature the BU has is that it contains all the physical fields in its description. By giving a special role to the present, we introduce a feature which has no correspondent in the matter fields. The BU accounts for the physical fields, but it cannot include an intrinsic present, and maybe doesn’t even need. Yet, if it would need to mark the present, a “BU with a bookmark” would solve the problem.

The registry view is compatible with both time evolution, and with the standard block universe view. And it shares with the EBU picture the compatibility with our feelings of time flow, free-will, open future, but not the carved in stone past.​]

Lastly and simply as a matter of interest: There seems to be a compelling parallel with another thread in the Biology/Evolution section that deals with free will, consciousness and evolution: http://www.scienceforums.net/topic/74370-since-we-have-no-free-will-what-purpose-doesdid-consciousness-serve/

Thanks for the more detailed clarification of two Absolute Spacetime variants.

BTW, I think that in the non-cited part there is probably an error: Wheeler’s delayed choice experiment does not prove that we can somehow change the past - but that's for another discussion! Anyway: while Bell suggested that a Lorentz ether may be the most straightforward solution, indeed this may not be obligatory even if a well documented and reproduced experiment would put the death nail in "local realism".

I get the impression that the "evolving block" variant is philosophically somewhere in-between Lorentz ether and Minkowski block; if you (or someone else) could improve on my generic block universe description as applied on the car example (post 78 ), that would be extremely useful.The main use of such models is to see them in action!

Maybe that will also partly address my questions concerning the causal explanatory capabilities of these variants,( post # 84).

Edited by Tim88
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Maybe its the physicist side of me. Definetely. When I look at a model. I'm only interested in one key question.

"What is its predictive power"

Lorentz ether offers nothing by introducing a preferred absolute frame.

If the process is symmetric (which block handles without a problem) Then you can use any frame as a reference.

"there is no preferred frame" is one of the philosophies of GR. There isn't a single detail that cannot be derived from using any frame conpared to using a rest frame.

So Lorentz ether does nothing to improve predictive power.

Block vs evolving block must be examined in the same manner.

Reversible processes are easy to predict.

Irreversible processes not so much.

Quantum fluctuations we are restricted to probability. Probability isn't deterministic its statistical. When we look at a waveform we only know that sonewhere on that wave is the particle. We don't know its precise location.

So how deterministic is this. Only as deterministic as the probability.

Block follows the philosophy "all events must be deterministic." In macro systems ordinarily this works but not in all cases. There are macro processes that are not reversible. Entropy for example isn't reversible.

If we start to reverse expansion we should have a decrease in entropy. According to reversible process.

However entropy doesn't decrease in this case. It will either remain the same or continue to increase.

arrow of time was proposed to be modelled via entropy. So this conflicts with block.

(Yes you guys can google the Internet to find counter arguments to the above examples) I know they are there...

The problem is the majority of those articles include a detailed math analysis.

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Maybe its the physicist side of me. Definetely. When I look at a model. I'm only interested in one key question.

"What is its predictive power"

[...Snip...]

Block follows the philosophy "all events must be deterministic." In macro systems ordinarily this works but not in all cases. There are macro processes that are not reversible. Entropy for example isn't reversible.

If we start to reverse expansion we should have a decrease in entropy. According to reversible process.

However entropy doesn't decrease in this case. It will either remain the same or continue to increase.

arrow of time was proposed to be modelled via entropy. So this conflicts with block.

(Yes you guys can google the Internet to find counter arguments to the above examples) I know they are there...

The problem is the majority of those articles include a detailed math analysis.

I gather it is the physicist side of you...which is perfectly understandable. I can only speak for the block universe approach, hence me snipping out the rest for the purpose of my response. I.t.o. the block universe approach the so-called arrow of time becomes a bit of a misnomer. Perhaps a arrow of location would be more descriptive..? *(Perceived)* entropy may indeed be different at different locations within the block universe. As I alluded to, that would then be a given...a physical and predetermined (unavoidable) property of being at (or experiencing) a different coordinate along said reality. Reversing expansion implies moving to another (prior) coordinate. All locations are equally real though, with its associated properties (w.r.t. entropy et al).

*(Edit)*

Here is another perspective, which was not googled. I have the book, so I apologise beforehand if copying from it may infringe copyright:

In “This Idea Must Die; Scientific Theories That Are Blocking Progress” there are a number of references to how our conventional paradigm may hinder our scientific understanding. In “Essentialist View Of The Mind” Lisa Barrett writes: In physics, before Einstein, scientists thought of space and time as separate physical quantities. Einstein refuted that distinction, unifying space and time and showing that they’re relative to the perceiver. Even so, essentialist thinking is still seen every time an undergraduate asks, “If the universe is expanding, what is it expanding into?” In “The Big Bang Was The First Moment Of Time” Lee Smolin states: What concerns me is the other meaning of Big Bang, which is the further hypothesis that the ultimate origin of our universe was a first moment in time, at which our universe was launched from a state of infinite density and temperature. According to this idea, nothing that exists is older than 13.8 billion years. It makes no sense to ask what was before that, because before that there wasn’t even time. The main problem with this second meaning of Big Bang is that it’s not very successful as a scientific hypothesis, because it leaves big questions about the universe unanswered… There is, however, a chance for science to answer these questions, and that’s if the Big Bang was not the first moment of time… For there to have been a time before the Big Bang, the Hawking-Penrose theorem must fail. But there is a simple reason to think it must: General relativity is incomplete as a description of nature, because it leaves out quantum phenomena… There is robust evidence from quantum cosmology models that the infinite singularities forcing time to stop in general relativity are eliminated…which allows time to continue to exist before the Big Bang, deep into the past. In “The Universe Began In A State Of Extraordinarily Low Entropy” Alan Guth argues: There’s an important problem, therefore, which is over a century old: to understand how the arrow of time could possibly arise from time-symmetric laws of evolution. The arrow-of-time mystery has driven physicists to seek possible causes within the law of physics we observe, but in vain. The laws make no distinction between the past and the future… The standard picture holds that the initial conditions for the universe must have produced a special low-entropy state because one is needed to explain the arrow of time. We argue, to the contrary, that the arrow of time can be explained without assuming a special initial state, so there is no longer any motivation for the hypothesis that the universe began in a state of extraordinarily low entropy. The most attractive feature of this idea is that there’s no longer a need to introduce any assumptions that violate the time symmetry of the known laws of physics. The basic idea is simple: We don’t really know if the maximum possible entropy for the universe is finite of infinite, so let’s assume it’s infinite. Then, no matter what entropy the universe started with, the entropy would have been low compared to its maximum. That’s all that’s needed to explain why the entropy has been rising ever since! He uses a metaphor of gas in a box (finite) compared to gas with no box where all particles will eventually start moving outwards and the gas will continue indefinitely to expand into the infinite space, with the entropy rising without limit. He continues: An arrow of time has been generated, without introducing any time-asymmetric assumptions. An interesting feature of this picture is that the universe need not have a beginning or an end.​

Edited by Memammal
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Maybe its the physicist side of me. Definetely. When I look at a model. I'm only interested in one key question.

"What is its predictive power"

Lorentz ether offers nothing by introducing a preferred absolute frame.

If the process is symmetric (which block handles without a problem) Then you can use any frame as a reference.

"there is no preferred frame" is one of the philosophies of GR. There isn't a single detail that cannot be derived from using any frame conpared to using a rest frame.

So Lorentz ether does nothing to improve predictive power.

Block vs evolving block must be examined in the same manner.

Reversible processes are easy to predict.

Irreversible processes not so much.

Quantum fluctuations we are restricted to probability. Probability isn't deterministic its statistical. When we look at a waveform we only know that sonewhere on that wave is the particle. We don't know its precise location.

So how deterministic is this. Only as deterministic as the probability.

Block follows the philosophy "all events must be deterministic." In macro systems ordinarily this works but not in all cases. There are macro processes that are not reversible. Entropy for example isn't reversible.

If we start to reverse expansion we should have a decrease in entropy. According to reversible process.

However entropy doesn't decrease in this case. It will either remain the same or continue to increase.

arrow of time was proposed to be modelled via entropy. So this conflicts with block.

(Yes you guys can google the Internet to find counter arguments to the above examples) I know they are there...

The problem is the majority of those articles include a detailed math analysis.

Hereby my excuses about my unnecessarily harsh comment of yesterday. I hope that my illustration explains how I felt and that it clarified better what this is about.

I would say that it was the mathematician side that took over, in a discussion focused on cause and effect, real and apparent; most equations fail to indicate such things. Cause and effect is very much the physicist side. Real and apparent belong to natural philosophy but frequently pop up in physics discussions. Modern physics is kind of missing a limb.

Now in detail, do you mean that according to block universe, time must be able to run backwards? I see no need for block adherents to claim such a thing, so I would not reckon it as a major flaw; it seems easily fixed by simply not making that claim. There is no problem to link to papers with a lot of math, but I don't see a reason to attack with much energy what may be a minor issue or even a straw man.

Further, the term "field" originally meant to be a description of the distribution of a property (typically force vectors) over a region in Space.

You seem to have adopted the trend to replace the word "space" by "field" and thus subtly modified its meaning to include Space as a physical entity. Such an extreme economy of words only serves to reduce comprehension: "field" as a property of "Space" separates two different concepts that are blurred by combining them in a single word. You could say that the same is true for calling "ether" "space", but here the simplification seems innocent to me, and thus its simplification preferable. That happens to be a topic of discussion of the "mother" thread.

Thus, if you write a space metric with (x y z) (and claim that it's a "field"?), unwittingly you are assuming Space without mentioning it.

It's our clarifications about how "field", vacuum, Space or Spacetime (or whatever pop name you want to give it) are claimed to interact with objects and clocks that matters for this discussion. No interaction = no effect = no clock retardation. A popular explanation by means of Spacetime is that a clock is a Spacetime odometer; for such a model to be possibly convincing, Spacetime must be substantial - as it is in block universe (thus I write it here with a capital S).

Another reminder: that either Space or Spacetime (or what names you want to give them) must be considered substantial is the starting assumption (postulate) of this discussion, following the current consensus in the mother thread "Is space-time a physical entity[..]".

PS. I see that Memammal already commented on the entropy objection, with somewhat different arguments.

And I really would like to see a better defense of the (evolving?) Spacetime "in action" with the car example, as I probably didn't present its case as well as can be done (e.g. explaining light propagation, limit speed c, simultaneity etc). As a matter of fact, as yet I didn't put to use the full explicative power of Space either (and I may not know all of it).

Edited by Tim88
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My vote is that an ether exists. All I know of its nature, is that it should uphold SR & GR, and play a role per QM in giving rise to energy and matter (fields). We may never be able to define it (except maybe by logical extrapolation) or prove it, but on the other hand.

I am not so sure that the block universe precludes free will, even though it is carved in stone. Also, I can envision the block universe, also as an evolving universe.

If presentism governs reality, then the relativistic effects would have to be un-real IMO. Therefore, I favor eternalism. However, I think that different people define eternal differently. If the universe has a finite temporal existence, it still may sit there in block format beginning-to-end. So we refer to it as eternal, because "all moments in time co-exist statically in a higher perspective", as opposed to "no cosmic beginning and/or no cosmic end". Its as though that higher perspective (we are not privied to) is outside-of-time (as we know it from experience), which could be interpreted as eternal.

Best regards,

Celeritas

Edited by Celeritas
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I do not vote for the presentism argument. Nor the Lorentz ether absolute frame being a privileged observer. Relativity of simultaneity has specific requirements that are not merely "convention" The presentism argument (if I understand it correctly) is a 3d ontology as opposed to a 4d ontology. Presentism follows the logic argument the view that it is only the present "here-now" (the three-dimensional world at the moment `now') that exists.
1) the universe exists only at the constantly changing present moment (past and future do not exist)

2) the universe is three-dimensional

It is more real to think of physical reality as a four-dimensional existence, instead of the evolution of a three-dimensional existence

First I better define relativity of simultaneity. ( mainly for other readers)

1) homogeneous and isotropic space means that no 3d location is privileged or more convenient.

2) homogeneity of time throughout a homogeneous space has no privileged origin or privileged

3) two events in the same frame of reference are simultaneous if the clocks at two locations is identical

4)Two distant events are simultaneous in a given inertial reference frame if the light signals originating from the points where the events take place arrive simultaneously at the middle point in-between these origin points

5)The two synchronized clocks have the same running time.

between frames

1) two light sources generated simultaneous arrive back at origin point 0 at the same time.

2) two light sources emitted at different time arrive back at the origin at the same time. if $t_1=\frac{\sqrt{x_1^2+y_1^2}}{c}$,$t_1=\frac{\sqrt{x_2^2+y_2^2}}{c}$

Presentism regards the event here-now as the most real, It should be stressed that it amounts to a contradiction in terms to say that the world is four-dimensional, but for every observer only the event "here-now" is real. If the world is four-dimensional all its events are equally real otherwise it would not be four-dimensional.This shows that in space time it is impossible to have an event, representing the event "here-now", which is more "real" than the other events. Therefore, objective now of time and objective becoming are impossible in a four-dimensional world, if they imply that there are events which are "more real" than the other space time events.

Secondly any view of "time is an illusion" does not reflect reality, because space and time are indissolubly related to each other to form a single whole, the presence of a force field in space must necessarily result in the appearance of physical properties of time caused by the motion of a body in this field. However this does not mean time is a physical property of matter or energy but is dependent upon the state of the space-time system via the force field interactions.

As physical also includes the definition "that which is measurable" time is measurable by the duration and rate of change in the system. Volume being a property which is 3d, is a physical property as it can be measured without changing the composition of the system. In a 4d view time and space are inseparable. So the correct ontology is space-time is also a property as it can be made without changing the composition of the system. As time is inseparable from space. Stating that one half of a whole is illusion while the other half is real is a contradiction.

(yes I spent some time studying the logic arguments)

Edited by Mordred
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Just to clarify something, one does not think of the manifold of space-time as a field - this is just nonsense - but the metric is a field. Classical fields are sections of various fibre bundles over a manifold.

In slightly less technical language, fields are well defined mathematical objects that you attach to space-time.

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Just to clarify something, one does not think of the manifold of space-time as a field - this is just nonsense - but the metric is a field. Classical fields are sections of various fibre bundles over a manifold.

In slightly less technical language, fields are well defined mathematical objects that you attach to space-time.

I hope I didn't inadvertently miss imply (I think I may have oops. good point must have been asleep. Should have been more clear..

I'd like to add a statement. It is one that involves lie groups of SR.

https://arxiv.org/abs/physics/0502115

"Belonging of coordinates transformation to a symmetry group indicates that all reference frames deﬁned by the transformation enjoy equal rights in relation to the property admitting this symmetry group. In other words in the bounds of the Lorentz group, i.e. among inertial frames of reference, there is no preferable reference frame"

Another feature in group is that SR preserves certain relations.

$\Lambda_\eta \Lambda^t=\eta$ which tells us that we preserve the Euclidean/galilean metric with respect to time.

On a sphere this can only be done as an infinitesimal approximation.

Edited by Mordred
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Having read through the most recent posts and in particular relevant parts of Mordred's post #111, it would appear that we are now merging onto the same reality plane w.r.t. the block universe (philosophically speaking).

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Mordred when you were inadvertently linking fields to manifolds were you actually thinking of the Lorenz group?

Wikipedia

Because it is a Lie group, the Lorentz group O(1,3) is both a group and admits a topological description as a smooth manifold

I have always contended that as soon as you introduce the word field, in the sense used here, four dimensions is not enough.

Wikipedia

The Lorentz group is a six-dimensional noncompact non-abelian real Lie group that is not connected

https://en.wikipedia.org/wiki/Lorentz_group

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Bold face mine:

My vote is that an ether exists. All I know of its nature, is that it should uphold SR & GR, and play a role per QM in giving rise to energy and matter (fields). We may never be able to define it (except maybe by logical extrapolation) or prove it, but on the other hand.

I am not so sure that the block universe precludes free will, even though it is carved in stone. Also, I can envision the block universe, also as an evolving universe.

If presentism governs reality, then the relativistic effects would have to be un-real IMO. Therefore, I favor eternalism. However, I think that different people define eternal differently. If the universe has a finite temporal existence, it still may sit there in block format beginning-to-end. So we refer to it as eternal, because "all moments in time co-exist statically in a higher perspective", as opposed to "no cosmic beginning and/or no cosmic end". Its as though that higher perspective (we are not privied to) is outside-of-time (as we know it from experience), which could be interpreted as eternal.

Best regards,

Celeritas

Indeed we are in a similar position as the ancient Greeks when they discussed if atoms existed (and apparently they concluded that atoms don't exist!).

But I'm baffled by your remark that I put in bold.

Space (Lorentz ether / Einstein's enhanced Lorentz ether) implies IMO presentism; and I illustrated with the car example how relativistic effects are real (apparent but not merely apparent or "un-real") according to that model. Please clarify by means of that same example how you drew the contrary conclusion as what I showed.

Best regards,

Tim88

[edit: precision]

Edited by Tim88
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I hope I didn't inadvertently miss imply (I think I may have oops. good point must have been asleep. Should have been more clear..

I think that you understand this well, but Tim88 I am not so sure...

Mordred when you were inadvertently linking fields to manifolds were you actually thinking of the Lorenz group?

Just for future reference, the Poincare group (Lorentz + translations) is a Lie group - that is both a smooth manifold and a group. Minkowski space-time can be considered as a homogeneous space of the Poincare group. In fact this approach is more used with the supersymmetric extensions or spaces like ADS and DS, but it is worth knowing.

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I think that you understand this well, but Tim88 I am not so sure... [..]

In order to attach unambiguous meaning to the non-mathematical aspects of his model, I already asked him to show it in action by means of the car example. That avoids hollow phrases and getting lost in meaningless discussions about words, which is all too often the problem with philosophical discussions. On that point I'm fully "Feynman".

Come on, people, with an elaboration of the car example I made a practical comparison between what "Space" and "Spacetime" supposedly can do on page 4, but likely I didn't do full justice to "Absolute Spacetime"; at least, I found my attempt less than satisfying and therefore probably unfair. Can't Block universe do more for understanding relativistic effects than giving a literal "perspective" and providing an "odometer" for clocks? When starting this thread, I supposed that that would have been dealt with upon reaching p.3...

My elaboration on bvr's practical example was meant to be the basis for following discussions.

But meanwhile we're already near the bottom of page 6 of this discussion with a lot of philosophical argumentation, but no improvement on my rather weak attempt on p.4.

I sure plan to discuss Mordred's anti-presentism arguments, however it's not immediately clear to me if he suggests any practical issues and first I want to get "back to business". In this discussion I'm mostly interested in "causal power" (however, self contradicting causal power is quite useless of course).

So, is there nobody following this discussion who can improve on my Absolute Spacetime interpretation of events with the traveling car, clarifying by means of that case example (and you may of course add accessories as needed) such things as light propagation, cause and effect, real and apparent, if there is "real one-way light speed", or other? With Frozen or Evolving Absolute Spacetime, as you wish.

And hopefully Celeritas can illustrate what he meant, with that same illustration, with "un-real" relativistic effects in Absolute Space. Also, if Mordred can clarify his presentism objection in practice by means of that same example, that could save quite some discussion.

I'll wait one day. Or longer, if you ask me in personal communication.

Thanks,

Tim88

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Let me ask of you Tim. My interpretation doesn't change anything in your car scenario.

Reason 1) no preferred frame= no need to use a third absolute frame. Comparison between two frames is sufficient to predict the change in geometry with a value of gamma.

Reason 2) Once you use the Lorentz transformations. You are already admitting Minkowskii geometry. Within each group are subgroups. SO(1.3)×SO(2)×U (1). See the group paper on SR I linked.

(Ajb pointed this out earlier.)

So Compare your absolute frame, which you cannot measure. With the rest frame.

in your car example what gamma value do you apply? Ether is a matter field.

1) you don't know the mass/energy density of the absolute frame.

2) You cannot confirm the geometry is $\eta_{\mu\nu}$

You are left making assumed properties of the state of the absolute frame. You have no way to confirm it.

Boils down to (measured properties of rest moving) compared to (Measured properties of inertial frame) both compared to a frame with no measurable properties....... We can't even confirm the length of the rod.

Makes absolutely no sense lol.

Moving to presentism. In block specifically means "Only the present exists". This is a 3d view, time is an illusion. This view also places a restriction (simultaneous events) Yet we know there are events that have no casaul connection between event a and event b.

How do you confirm these are simultaneous events.? I posted the criteria prior.

So here is a question Which observer "present" is more real ?

1)absolute frame (cannot measure,only assume)

2) rest frame

3) inertial frame.

Using any of the above under presentism each of the three observers feels his own frame is more real. Each will view the other frame as inertial.

No frame can be confirmed as more "Real"

The 3d kinematics of each frame are identical in symmetric relations. All three frames preserve the Pythagoras metric. So what tool do you use to confirm one frame is more real than another?

In the 4D the philosophy is no frame is privileged. All observers are correct (his frame is real ) but it admits that another observer will see his frame equally real.

There is no way to prove one frame being more real than another. (eternalism)

"Eternalism is a philosophical approach to the ontological nature of time, which takes the view that all points in time are equally "real",

If you wish to use Block the eternalism view is more real than the presentism view. The presentism view cannot confirm his frame is more real than any other.

Eternalism view is compatible with the 4d view. This is the view relativity uses.

(a side note, this thread could have been shortened with less confusion. By simply asking opinions on which is more real "Presentism-Lorentz ether. or Eternalim-Minkowskii) under block philosophy.

In the GR realm the quantities that all class of observers can agree on (invariant) is proper. This is only achievable by the eternalim view.(under block)

"In relativity, proper time along a timelike world line is defined as the time as measured by a clock following that line"

Any point on that worldline is equally real.

(the above is on the assumption of deterministic aka Block) Quite frankly I don't particularly find Block adequate but Thats another debate. For another time

(I tried to keep this restricted to block and Lorentz ether as per your OP)

Edited by Mordred
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I do not vote for the presentism argument. Nor the Lorentz ether absolute frame being a privileged observer. Relativity of simultaneity has specific requirements that are not merely "convention" ...

It is more real to think of physical reality as a four-dimensional existence, instead of the evolution of a three-dimensional existence ...

Presentism regards the event here-now as the most real, It should be stressed that it amounts to a contradiction in terms to say that the world is four-dimensional, but for every observer only the event "here-now" is real. If the world is four-dimensional all its events are equally real otherwise it would not be four-dimensional...

If you wish to use Block the eternalism view is more real than the presentism view. The presentism view cannot confirm his frame is more real than any other.

Eternalism view is compatible with the 4d view. This is the view relativity uses.

Thank you Mordred for clarifying that. I agree with your opinions above and they are also in line with at least two other findings that I previously referenced:

Vesselin Petkov​'s Is there An Alternative To The Block Universe View

And Springer Berlin Heidelberg's Relativity of Simultaneity and Eternalism: In Defense of the Block Universe

Edited by Memammal
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Mordred when you were inadvertently linking fields to manifolds were you actually thinking of the Lorenz group?

I have always contended that as soon as you introduce the word field, in the sense used here, four dimensions is not enough.

https://en.wikipedia.org/wiki/Lorentz_group

The link for connected seems off.... A connected element is a tensor.

O(1.3) orthogonal group has 4 connected groups (tensors) the two that preserve time. The two that preserve time fall under O+(1,3) the two that preserve space are under SO(1,3)

the elements that preserve both space and time are under SO+(1,3). Both SO(1,3) and SO+1,3) have 6 dimensions. The SO(1,3) is doubly covered by SU(2)/Z

Anyways number of dimensions isn't the approach, that's just our coordinates under the Lorentz group you have 16 elements, which are constrained such that any transformation can be determined by 6 parameters 3 for rotation and 3 for boosts.

The inhomogeneous Lorentz group or Poincare group has 10 parameters, 4 for space-time translation and 6 for homogeneous Lorentz transformation. Under Minkowskii metric the Poincare group is the full group. With the Lorentz group as a subgroup.

A field is a function of a space-time point if that point is defined as an event. $x^\mu=(t,\overrightarrow{x})$ This is what I was thinking, but should have clarified. prior to connecting fields to the metric. Essentially a field is a collection of objects. Those objects can be events.

where k is the boosts are 4*4 matrices, and L are your 4*4 matrix rotations. these matrix can be defined as

$(K_i)^j_k=0$, $(K_i)^o_\mu=(K_i)^\mu_o=g^i_\mu$

$(L_i)^i_k=\epsilon_{ijk}, L^0_\mu=L^\mu_0=0$ where i,j,k=1,2,3 and $\mu=0,1,2,3$

I'm not sure if that helps with your question or adds confusion lol

Edited by Mordred
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The link for connected seems off.... A connected element is a tensor.

O(1.3) orthogonal group has 4 connected groups (tensors) the two that preserve time. The two that preserve time fall under O+(1,3) the two that preserve space are under SO(1,3)

the elements that preserve both space and time are under SO+(1,3). Both SO(1,3) and SO+1,3) have 6 dimensions. The SO(1,3) is doubly covered by SU(2)/Z

Anyways number of dimensions isn't the approach, that's just our coordinates under the Lorentz group you have 16 elements, which are constrained such that any transformation can be determined by 6 parameters 3 for rotation and 3 for boosts.

The inhomogeneous Lorentz group or Poincare group has 10 parameters, 4 for space-time translation and 6 for homogeneous Lorentz transformation. Under Minkowskii metric the Poincare group is the full group. With the Lorentz group as a subgroup.

A field is a function of a space-time point if that point is defined as an event. $x^\mu=(t,\overrightarrow{x})$ This is what I was thinking, but should have clarified. prior to connecting fields to the metric. Essentially a field is a collection of objects. Those objects can be events.

where k is the boosts are 4*4 matrices, and L are your 4*4 matrix rotations. these matrix can be defined as

$(K_i)^j_k=0$, $(K_i)^o_\mu=(K_i)^\mu_o=g^i_\mu$

$(L_i)^i_k=\epsilon_{ijk}, L^0_\mu=L^\mu_0=0$ where i,j,k=1,2,3 and $\mu=0,1,2,3$

I'm not sure if that helps with your question or adds confusion lol

Yes, thanks for the reply I'm aware of most of that, though I am not so slick with aggregated objects.

When you want a satisfactory answer in the real world you have to work out all the bit individually and I think the aggregation can obscure some of the properties and consequences.

Two points

There are issues with defining an 'event' as a point in spacetime due to its pointlike nature.

Under this view you are forced to separate occurrences at the point (event) from the point (event) itself.

This implies that spacetime is more than a mathematical model since there is something that can be separated.

This view is, however, consistent with the use of the word 'Field' here.

For a field here is an indexing system, with as many dimensions as there are indices, that identifies unique objects placed at any given index set.

Of necessity, the object introduce their own dimensions, additional to the index ones.

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1. Stationary ether (Absolute Space model): ...

1d. Moreover, the clocks of the car truly tick slower; this is physically understandable by means of the "light clock" illustration (e.g. Simple_inference_of_time_dilation ). Due to the car's (mis)synchronization of clocks (together with its length contraction), it seems from the car's perspective as if instead the ground clocks run slow.

Tim88,

I’m of the opinion that presentism can only apply to absolute time. The moment one allows light speed to be isotropic in at least one frame, eg Lorentz’s ether frame, the gamma factor arises in the model of space and time. The gamma factor requires some sort block universe IMO, a fused space-time continuum, the only reasonable explanation to date. While attempts have been made to validate LET using ad-hoc explanations, none have ever been satisfactory. The Fitzgerald length-contraction arose mathematically in the MMX null result analysis, however “Poincare stresses” certainly don’t explain the physical source of a length-contraction. The block universe does explain it, as the physical source is all in the geometry of space-time.

You’ve stated in your car-scenario post (page 4) that …

(real) length-contraction + (mis)synchronization = (apparent) time dilation

However, no valid “physical reasoning” for real-length-contraction has ever been given in the very first place. That must be explained first, before the subsequent part (ie.) …

+ (mis)synchronization = (apparent) time dilation

… may be validly argued.

The physical source for real length-contraction was assumed to be ad-hoc "Poincare stresses". So apparent-time-dilation being the result of “Poincare stresses” plus human-error in clock-synchronization ... is a non-sequitur IMO. There is simply no good physical explanation for the source of the relativistic effects, other than some sort of block universe.

I figure an ether exists, but no master frame is likely associated. How to define an ether as such, while making compatible a block universe and our experience of only an ever changing NOW? This is the challenge in my mind.

Best regards,

Celeritas

Edited by Celeritas
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It is more real to think of physical reality as a four-dimensional existence, instead of the evolution of a three-dimensional existence

Some Einstein quotes:

<< From a "happening" in three-dimensional space, physics becomes, as it were, an "existence" in the four-dimensional "world". >>

(Albert Einstein. "Relativity: The Special and the General Theory." 1916. Appendix II Minkowski's Four-Dimensional Space ("World") (supplementary to section 17 - last section of part 1 - Minkowski's Four-Dimensional Space).

<< Since there exists in this four dimensional structure [space-time] no longer any sections which represent "now" objectively, the concepts of happening and becoming are indeed not completely suspended, but yet complicated. It appears therefore more natural to think of physical reality as a four dimensional existence, instead of, as hitherto, the evolution of a three dimensional existence. >>

(Albert Einstein, "Relativity", 1952).

<<...for us convinced physicists the distinction between past, present, and future is only an illusion, although a persistent one." >> ( Letter to Michele Besso family, March 21, 1955. Einstein Archives 7-245).

----------------------

Also, Karl Popper about his encounter with Einstein:

<< The main topic of our conversation was indeterminism. I tried to persuade him to give up his determinism, which amounted to the view that the world was a four-dimensional Parmenidean block universe in which change was a human illusion, or very nearly so. (He agreed that this had been his view, and while discussing it I called him "Parmenides".)... >>

(Karl Popper, Unended Quest: An Intellectual Autobiography.Routledge Classics. Routledge. pp.148–150).

----------------------

Petkov makes an interesting comment about Lorentz failing to understand all times are equally 'real':

Quote: <<It was precisely the view, that successful abstractions should not be regarded as

representing something real, that prevented Lorentz from discovering special relativity.

He believed that the time t of an observer at rest with respect to the aether (which is a genuine example of reifying an unsuccessful abstraction) was the true time, whereas the quantity t' of another observer, moving with respect to the Ørst, was merely an abstraction that did not represent anything real in the world. Lorentz himself admitted the failure of his approach: <<The chief cause of my failure was my clinging to the idea that the variable t only

can be considered as the true time and that my local time t'

must be regarded as no more than an auxiliary mathematical quantity. In

Einstein's theory, on the contrary, t' plays the same part as t; if we want

to describe phenomena in terms of x'; y'; z'; t' we must work with these

variables exactly as we could do with x; y; z; t.>>

>>

http://fqxi.org/data/essay-contest-files/Petkov_PetkovFQXi2.pdf

I also found this in my files:

<If I had to write the last chapter now, I should certainly have given a more prominent place to

Einstein’s theory of relativity [...] by which the theory of electromagnetic phenomena in

moving systems gains a simplicity that I had not been able to obtain. The chief cause of my

failure was my clinging to the idea that the variable t only can be considered as the true time

and that my local time t′ must be regarded as no more than an auxiliary mathematical

quantity.> (Lorentz 1916, p. 321, note 72*)

Edited by VandD
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Tim88,

I’m of the opinion that presentism can only apply to absolute time. The moment one allows light speed to be isotropic in at least one frame, eg Lorentz’s ether frame, the gamma factor arises in the model of space and time. The gamma factor requires some sort block universe IMO, a fused space-time continuum, the only reasonable explanation to date. While attempts have been made to validate LET using ad-hoc explanations, none have ever been satisfactory. The Fitzgerald length-contraction arose mathematically in the MMX null result analysis, however “Poincare stresses” certainly don’t explain the physical source of a length-contraction. The block universe does explain it, as the physical source is all in the geometry of space-time.

You’ve stated in your car-scenario post (page 4) that …

(real) length-contraction + (mis)synchronization = (apparent) time dilation

However, no valid “physical reasoning” for real-length-contraction has ever been given in the very first place. That must be explained first, before the subsequent part (ie.) …

+ (mis)synchronization = (apparent) time dilation

… may be validly argued.

It seems to me that a (begin of a) "physical reasoning" for real-length-contraction was given by Tim88:

1a. The car is then Lorentz contracted due to the car's motion through space, as would be expected if fundamentally all matter consists of some kind of waves.

Celeritas said:

The physical source for real length-contraction was assumed to be ad-hoc "Poincare stresses". So apparent-time-dilation being the result of “Poincare stresses” plus human-error in clock-synchronization ... is a non-sequitur IMO.

The ad-hoc qualification is surely right when speaking of the theories around 1900. At that time, matter was considered to be (ideally) totally rigid, so there was no possible explanation for the length-contraction.

But is that still true, regarding the modern view on particles, atoms and molecules?

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