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

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Gosh, Mordred, those last two posts were from the heart not the head?

I can only council the warning about this greatest scientific error of doctrine

"The latest theories are superb and absolutely correct. All previous theories are bunkum."

Many a great scientist has suffered at least a red face when following this doctrine.

I can best refer you to Sir Harold Jeffreys's Book Scientific Inference, chapter VIII in my second edition, Cambridge University Press.

The mathematics and mathematical philosophy are discussed in great detail, in particular where, why and how you need second order effects to eliminate older, more obvious explanations for the observed phenomena.

I also refer you to the most current, bang up to date, text

Dynamics and Relativity, W D McComb - Oxford University Press, pages 222 to 225

Where Mccomb discusses what he calls four-space in terms of my (Minkowski) offering.

He dubs this" the older version" where he treats the Lorenz transformations in terms of rotations

and what he dubs" the modern version" where he treats four-space in terms of constructing a vector space with a suitable inner product.

Now Tim has asked for some tangible model (I think) and I would say that the Minkowski approach treating four-space as an extension of what went before provides this,

Whereas a totally artificial mathematical construct of a particular vector space equipped with specific inner and exterior products is less 'tangible'

Edited by studiot

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As this thread is in the philosophy section we should discuss some philosophy...

Fair enough an interest was presented on the QM side of the block universe. For that the example relates to deterministic and indeterminate aspects.

Many felt that QM was incomplete as it is inherently indeterministic. Uncertianty principle being one example. Entanglement for another. There are more.

So various theories categorized under "hidden variables" Pilot-wave theory being one the earlier examples.

The hidden variable models would fit well under "block universe" as the requirement of a block universe is deterministic.

However hidden variables were later shown to be wrong. Bells inequality.

@Studiot there are better ways to make GR tangible within GR than using models that are at best "controversial".

That was my point on the last two threads. There are classical "heuristic views" within GR. Adding classical thermodynamics makes understanding those heuristic views easier.

A good example is one done by Andrew Liddle. I can post the metrics later if anyone is interested. For that matter one of his books on GR is entirely done using Newtonian style math.

Took me a bit to find this. It is a model designed to aid understanding to GR for non scientists....These aren't the original papers. I haven't been able to locate the originals which aided my learning. Both are arxiv coverage...

River model of black holes.

River Model of space.

If I recall the original was titled "River model of time" the paper kept the math far simpler than presented in the above two.

This model seems reasonable. Yet it is limited. Can anyone identify whats missing?

Edited by Mordred

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Now discussions about details and even what sounds like Church doctrines (which have no place in science!) have already taken off, before coming to the point by means of a clear and simple, worked out example for newcomers in which the two historical interpretations of the Lorentz transformations are fairly compared.

I hope we can postpone further discussions until after comparing their basic merits; that will be more useful for later visitors of this thread.

Basic fact: similar to classical mechanics, you are free to choose the landscape as pretended "rest frame" (neglecting rotation), in which case your car is "moving".

I will borrow from a recent thread a pictorial presentation of a fast car (original by bvr and improved by me):

Different from common practice, we assume here that the car conductor has set up an inertial reference system according to the assumption that the car is in rest and the ground is moving under it. Moreover the car happens to be driving at the crazy speed of 0.86c.

Let's say that there are clocks c1 and c2 above two openings in the car, and these clocks have been "Einstein synced".

Now the car driver drops two balls, presumably simultaneously, so that from his perspective :

_________________________
| |
| |_
| ___ c1 c2 ___|
/ \--- ----1m---- ---/ \

_______\___/___o__________o___\___/_________

<- v

According to the car the balls were dropped simultaneously at 1 m distance, so that they also hit the moving ground at 1 m distance.

According to the ground however the car is length contracted, and the balls are not dropped at the same time so that they hit the ground at different times:

_____________
| |
| |
| | v ---->
/ \- -----o-/ \
____________\_/___o_____\_/_____________________________________

______________
| |
| |
| | v ----->
/ \- ----- -/ \
__________________o________\_/2m_____o_\_/____________________________

Distance between the corresponding events as measured with a ruler on Earth in blue.

Now the differing worldviews:

1. Stationary ether (Absolute Space model): When you are driving your car, in general both your car and the landscape are in motion, resulting in what may be figuratively called different perspectives of the same reality. This is an essential point to keep in mind before reading on. Only for simplicity of explanation we'll first pretend in this introduction that the landscape is, by pure chance, in "absolute rest".

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. In this example one could (in principle) measure that the car is half its proper length.

1b. The car's synchronization is in this case also messed up due to the car's motion, as can be easily understood by working out the timing errors from the light pulses as they propagate through space (we may ignore the air). Thus the car's synchronization is chosen such that it seems as if the one-way speed of light (also called "closing speed") is the same in both directions.

1c. As per the relativity principle these effects combine so that according to the car conductor it seems as if the ground is length contracted. Moreover, just as was the case in Newtonian mechanics, the same relationships occur between two reference systems in uniform translational motion. In other words, both inertial reference systems provide in general a somewhat "distorted" perspective on reality. Note that these combined effects are not a "conspiracy", as the PoR follows from the conservation laws.

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.

2. Block universe (Absolute Spacetime model): When you are driving your car, you are selecting (or experiencing) a slice out of Spacetime; motion is a perception caused by your Spacetime trajectory.

2a. The car appears Lorentz contracted to half its length from the perspective of the ground frame due to the car's trajectory through Spacetime which is at a different spacetime angle than the ground trajectory. The physical explication as to why this is the case is that "time" is an unexplained illusion from our senses. Everything is just trajectories through Spacetime that we can "slice" in different ways.

2b. The car uses the standard synchronization convention, such that the spacetime trajectory of light relative to the car appears to be symmetric in both directions.
Also here one is free to choose the "angle", that is, the apparent one-way speed of light (also called "closing speed") relative to the car.

2c. The relativity principle is automatically built into this model. Here the relativistic effects are due to the different trajectories, affecting the recorded amount of "space" and "time" as if an odometer is tracing Spacetime.

2d. While the clocks in the car in reality don't tick at all, the perceived tick rate is just as truly the normal rate as those of that of clocks on the ground. Time dilation is again a matter of perspective, due to the different trajectories. A peculiarity is that a longer Spacetime trajectory between two points corresponds to less proper time increase.

[...] I meant that, at some time, the car accelerated wrt the landscape, and that in my opinion, that change in motion has a physical sense. [...]

Yes, we should definitely include that fact - and to round it off we can easily make it a "twin paradox" scenario.

Let's just take a nearly infinitely sharp turn (ignoring the impossibly strong acceleration effects) and drive back without changing speed. Follow again the differing interpretations.

Absolute Space model: For clarity of discussion only, we'll again first explain with the simplification that the ground is by chance in "absolute rest".

1e. The car is just as much length contracted as before. However, this time the car driver notices that his reference system has been messed up: the speed of light doesn't seem the same anymore in both directions. This follows directly if one considers that the true speed of light is the same as before, while the absolute effect of speed on the car's clocks is approximately the same (in this case the true clock rates can in theory be kept identical). Consequently the observational symmetry has been broken, and the absolute effects resulting from speed relative to the ether can thus be detected.

1f. If the car now passes clocks on the ground that it passed earlier in the other direction, the driver will notice that his clocks are behind on the ground clocks. That is as expected, since his clocks (in this simplified case) truly ticked slower all the time.

As the Lorentz transformations form a group similar to the Galilean transformations, the exact same phenomena are observed between a car in motion relative to a ground that itself is also in motion. While this point may be less intuitive due to our limited mental capability to conceive such complexity of different relative motions and effects, it is not too difficult to verify this fact mathematically.

Absolute Spacetime model:

2e. From the grounds perspective, the car is just as much length contracted as before because its trajectory has changed but the relative space-time angle is the same. However, this time the car driver notices that his reference system has been messed up: the speed of light doesn't seem the same anymore in both directions. This is because the car has made a turn in Spacetime, changing its trajectory through it. That is an absolute effect; the clocks were synchronized in relation with a different trajectory.

2f. If the car now passes clocks on the ground that it passed earlier in the other direction, the driver will notice that his clocks are behind on the ground clocks. That is as expected, since the Spacetime trajectory is longer between the same events (a curved line compared with a straight line).

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

Space and Spacetime are thus competing concepts of a not directly detectable "background" on which events take place. Studiot's book reference pretends that "block universe" is the "mainstream" view but I don't think so; I agree with ajb that most people working in modern physics are less worried with the philosophical implications than they are with matching theory with observation.

Important philosophical consequences of the "Absolute Space" view of reality are that time and distance have not been totally robbed from their classical, intuitive aspects; however, physical length in the direction of motion and time rate are affected by motion through Space. In other words, only Space is causal in that view.

Important philosophical consequences of the "Absolute Spacetime" view of reality are that time and distance have been totally robbed from their classical, intuitive aspects: space and time form a single physical entity (studiot's book reference: "like a giant block of ice"), in which at least all events in the past and present (and commonly also the future, but that may not be necessary) "coexist and are frozen in their locations in space and time". In the Spacetime view, Space and Time are coexisting causal physical entities, or even different aspects of a single causal physical entity.

Please tell me if I made any errors.

We should still give examples of interpretations of energies as well as GR effects. And the Flowing Space model that Mordred just introduced will also be interesting to discuss. [edit:] I'm not sure if it is totally compatible with GR.

Edited by Tim88

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not totally the metrics don't include the conservation laws. Also the scenarios where the River model accurate is limited.

Lorentz Ether used strictly for Heuristic views also suffers limitations.

I already mentioned limitations of the block universe.

to save time. Here is a Lorentz ether paper used strictly as a heuristic view compares to the River model.

it describes the philosophy aspects and limitations of both models.

The above doesn't look too bad. The last paper will definitely help provide an approach direction.

Edited by Mordred

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Fair enough an interest was presented on the QM side of the block universe. For that the example relates to deterministic and indeterminate aspects.

Many felt that QM was incomplete as it is inherently indeterministic. Uncertianty principle being one example. Entanglement for another. There are more.

So various theories categorized under "hidden variables" Pilot-wave theory being one the earlier examples.

The hidden variable models would fit well under "block universe" as the requirement of a block universe is deterministic.

However hidden variables were later shown to be wrong. Bells inequality.

@Studiot there are better ways to make GR tangible within GR than using models that are at best "controversial".

That was my point on the last two threads. There are classical "heuristic views" within GR. Adding classical thermodynamics makes understanding those heuristic views easier.

A good example is one done by Andrew Liddle. I can post the metrics later if anyone is interested. For that matter one of his books on GR is entirely done using Newtonian style math.

Took me a bit to find this. It is a model designed to aid understanding to GR for non scientists....These aren't the original papers. I haven't been able to locate the originals which aided my learning. Both are arxiv coverage...

River model of black holes.

River Model of space.

If I recall the original was titled "River model of time" the paper kept the math far simpler than presented in the above two.

This model seems reasonable. Yet it is limited. Can anyone identify whats missing?

Lindner's paper on that: http://home.epix.net/%7Ehhlindner/Writings/Nature.pdf

not totally the metrics don't include the conservation laws. Also the scenarios where the River model accurate is limited.

Lorentz Ether used strictly for Heuristic views also suffers limitations.

I already mentioned limitations of the block universe.

to save time. Here is a Lorentz ether paper used strictly as a heuristic view compares to the River model.

it describes the philosophy aspects and limitations of both models.

The above doesn't look too bad. The last paper will definitely help provide an approach direction.

A model of reality that doesn't conserve energy, with ether forever flowing into the Earth is IMHO born dead...

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True the specific model above doesn't survive under robust examination. But then again neither does block or Lorentz ether.

The flow of time aspect has numerous models. One that tries to couple quantum gravity to GR being Wheeler-Dewitt.

If you think the above is strange. Try the Wheeler-Dewitt modelling of "No Time" lol

Or Rovelli's time without spacetime.

Or 6d (4 spatial +2 time coordinates)

(not saying these are bad models. They work for the conditions they are designed for)

A model of reality that doesn't conserve energy, with ether forever flowing into the Earth is IMHO born dead...

Well here is another space flow model view using Lorentz Ether lol

General relativity on spatial flows...

Edited by Mordred

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Tim88,

Regarding whether space is a "physical thing", I would say yes. Space and time are both measurable.They exist, whether we have completely defined them as yet, or not. Tangibility is not the only requirement for physicality.

Add, space is a continuum, and per SR spacetime is a continuum. You asked whether space is a "physical thing". Being of continuum nature, I say yes. And besides, the gravity-well (or curved spacetime, if you prefer) is an extension of the particle, always forever traveling with the body that creates it. Two aspects of a single underlying mechanism. To say particles have physical properties, while the other half of their own mechanism does not, makes no sense to me personally.

Granted, there are debates in physics today as to whether time really exists. Some, actually argue that only time is fundamental. So I address your questions as per the consensus of today, ie that space and time are assumed to exist. I have little doubt personally, that our definitions of space and time will expand with time.

Best regards,

Celeritas

The flow of time aspect has numerous models. One that tries to couple quantum gravity to GR being Wheeler-Dewitt.

If you think the above is strange. Try the Wheeler-Dewitt modelling of "No Time" lol
Or Rovelli's time without spacetime.

I've never quite understood the "no time" arguments, even though I understand the block universe model. While the worldlines of a block universe are static in 4-space, this does not prevent the advancement of lines-of-simultaneity along those worldlines. That is, there could be "an activity" that exists within an otherwise static block universe. IOWs, even in the Minkowski 4-space model where time is a 4th spatial axis, time still advances along any worldline at the rate of proper time. No matter what rate one might imagine lines-of-simultaneity to advance, all events still occur at the same predictable clock readouts, regardless. So the rate of proper-time seems unrelated to worldlines or spacetime solns. Given we experience time's passage, the block universe must in some way comply IMO.

Best regards,

Celeritas

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The no time implies that time isn't a fundamental but an emergent property. In essence. The Wheeler Dewitt equations describe the fundamental geometries of infinitesimal tetrahedrons. a common terminology is spin foam.

Remember the good ole "is space lumpy or smooth arguments lol.

Anyways the Dewitt equation is treated as the fundamental. This equation does not include time. Time emerges when you add a matter field to the Dewitt fundamental field. Essentially it is a canonical quantum gravity solution. Where time emerges from the 3-metric as the configuration variable. It really boils down to is time fundamental or emergent.

The field that carries this forward is quantum geometrodynamics. The Wheeler Dewitt equation is a major aspect of geometrodynamics.

Personally There are aspects I do like in geometrodynamics but it does require a different philosophy on time. The aspect I like is dealing with quantum numbers and waveforms of QM. Geometrodynamics handles the QM side far better than relativity.

However it becomes tricky to get it to work for every macro scale scenario. Added degrees of freedom. additional tensors etc. Not saying it isn't possible but it isn't easier.

edit: hopefully I didn't mess up on the above. lol its not my strongest model on understanding. Which is extremely amusing considering I've been proof reading a 1000 plus page dissertation on the subject for a friend. Thankfully he is aware it's not my strongest subject lol. (may have asked me for that reason to test how understandable his dissertation is) Though I have familiarity with what he is trying to model under geometrodynamics. SO(10) Pati-Salam subgroups with Higgs field.

I've been at that paper for several months now 👹.

Edited by Mordred

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True the specific model above doesn't survive under robust examination. But then again neither does block or Lorentz ether.

The flow of time aspect has numerous models. One that tries to couple quantum gravity to GR being Wheeler-Dewitt.

If you think the above is strange. Try the Wheeler-Dewitt modelling of "No Time" lol

Or Rovelli's time without spacetime.

Or 6d (4 spatial +2 time coordinates)

(not saying these are bad models. They work for the conditions they are designed for)

Well here is another space flow model view using Lorentz Ether lol

General relativity on spatial flows...

Models with incorrigible serious flaws are not suitable for this discussion; the flaws that I perceive in "flowing space" certainly do look serious.

In contrast, I thought that both Lorentz ether ("Space") and Minkowski block universe ("Spacetime") are self consistent, matching observations and fundamental laws of physics, as enhanced by GR. If you can disprove either on such grounds, that will be illuminating (and you'll prove either Minkowski or Einstein wrong).

Then, from being forced to phrase the block universe myself, I found that I have conceptual difficulties with the necessary homogeneity of block universe so that I'm not sure that it is self consistent; I wonder if it's a homogeneous inhomogeneous block of ice that cannot exist. But probably it's just that my mind is not managing understanding of such counter intuitive concepts! That may be something to explore in a fork from this thread.

And from exploring the example, a related question crystallized about how a block universe explains light propagation. Maybe it just doesn't? Specifically, what is the block universe explanation and interpretation of the fact that observers can freely choose the one-way ("closing") speed of light, so that this speed can be made isotropic with respect to our preferred reference body, and anisotropic to others? "Proper time rate" cannot work as the light's proper time is "frozen", so what then?

Tim88,

Regarding whether space is a "physical thing", I would say yes. Space and time are both measurable.They exist, whether we have completely defined them as yet, or not. Tangibility is not the only requirement for physicality.

Add, space is a continuum, and per SR spacetime is a continuum. You asked whether space is a "physical thing". Being of continuum nature, I say yes. And besides, the gravity-well (or curved spacetime, if you prefer) is an extension of the particle, always forever traveling with the body that creates it. Two aspects of a single underlying mechanism. To say particles have physical properties, while the other half of their own mechanism does not, makes no sense to me personally.

Granted, there are debates in physics today as to whether time really exists. Some, actually argue that only time is fundamental. So I address your questions as per the consensus of today, ie that space and time are assumed to exist. I have little doubt personally, that our definitions of space and time will expand with time.

Best regards,

Celeritas

[..]

I did not ask if space is a physical thing; it was discussed in the "mother" thread where I presented strong arguments for the conclusion that there must be a physical space corresponding to mathematical space. This thread is a continuation in part for those who are interested to explore that insight in more detail and thus help improving understanding of relativity.

In the "Absolute Space" view (or my version of it, as this is very philosophical), time is not a physical "thing" in itself but a human concept derived from the observation of physical processes; and processes are not things either.

Meanwhile in the course of this discussion, a couple of questions about the block universe view came up [a little above in this post]; maybe you can clarify.

Edited by Tim88

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I've never quite understood the "no time" arguments...

The biggest problem is that in our standard canonical formulation of quantum theory time plays a special role and one that is different to space. The ethos of Einsteinian relativity is that we should treat space and time equally, but in a canonical quantum theory this is not easy.

If you apply the ADM formulation of general relativity (which used a space-time cut) you see that one does not really have dynamics, but rather a Hamiltonian constraint.

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Models with incorrigible serious flaws are

In contrast, I thought that both Lorentz ether ("Space") and Minkowski block universe ("Spacetime") are self consistent, matching observations and fundamental laws of physics, as enhanced by GR. If you can disprove either on such grounds, that will be illuminating (and you'll prove either Minkowski or Einstein wrong).

I would consider Lorentz ether as seriously flawed. All tests designed to find this Ether has failed.

Wouldn't you consider that a flaw?

Are you familiar with these tests and Ether drag which is inherent of any medium?

Have you ever seen any research correlating the Lorentz Ether with thermodynamic properties? Every other particle in the SM model has this correlation. Why doesn't Ether?

How precisely do you apply the conservation laws to this Ether which you consider "More Real".

Yet you turned down the Ether flow model in the last link based on lack of conservation laws.

So show me those conservation laws for Lorentz Ether...

As Ajb mentioned earlier the Lorentz ether modelling requires extremely specialized properties and a total lack of any form of coupling to account for lack of thermodynamic influence.

The River model is a form of Minkowskii block. However it isn't designed as a replacement for GR. Its merely designed as an instruction aid. Perhaps you missed that detail in the articles.

The last link only appears on the surface to be the same but its not.

(I would consider something that is undetectable by any means as seriously flawed. Ether)

I did not ask if space is a physical thing; it was discussed in the "mother" thread where I presented strong arguments for the conclusion that there must be a physical space corresponding to mathematical space. This thread is a continuation in part for those who are interested to explore that insight in more detail and thus help improving understanding of relativity.

There is its called fields. Or if you want to stay strictly classical the distribution and pressure influence of the standard model of particles.

Aka stress tensor....

All of which are detectable and include those conservation laws.

I have to ask. I know your familiar with SR. How familiar are you with the Einstein field equations?

I guess the next question is How do you define physical? Any property described by physics is physical. This includes temperature, pressure, wave functions, volume, length even time by definition.

Physical property: is any property that is measurable, whose value describes a state of a physical system. The changes in the physical properties of a system can be used to describe its transformations or evolutions between its momentary states.

https://en.m.wikipedia.org/wiki/Physical_property

by definition reference frames are physical states.

Perhaps if you clarify precisely what specific property you are looking for.?

More specifically that cannot be modelled using fields?

Edited by Mordred

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I would consider Lorentz ether as seriously flawed. All tests designed to find this Ether has failed.

Wouldn't you consider that a flaw?

Are you familiar with these tests and Ether drag which is inherent of any medium [..]

Thanks for reminding readers that the Stokes ether model (a kind of material "flowing Space") had been disproved. As also the tests designed to find Maxwell's ether failed, Lorentz made important modifications that led to new unheard of predictions. The tests designed to verify these new predictions (starting with electron motion in EM fields) are the tests of what later was named "Special Relativity" by Einstein. Not a trace of a flaw there!

[..]

How precisely do you apply the conservation laws to this Ether which you consider "More Real".

I already mentioned as part of the Lorentz ether explanation of SR that the (special) relativity principle can be derived from the conservation laws, based on the Lorentz ether (if you like I can give a reference to a paper in which the derivation is done). It's immediately understood if one realizes that the Lorentz ether mathematically corresponds to labeling an unknown frame "the Lorentz ether". So that's another misunderstanding.

[edit:] I hope that you understand the block universe models better, because I am interested in your counter arguments to those.

[..] The River model is a form of Minkowskii block. However it isn't designed as a replacement for GR. Its merely designed as an instruction aid. Perhaps you missed that detail in the articles.

Perhaps you misunderstood the purpose of this topic? However I agree that the River model was an interesting one to mention as an example of another model that emulates many of the phenomena while at the same time being incorrect; I did not fully read these articles although I read some in the past. It reminds me of the fact that we can successfully model an ecological high quality voltage source as a current source with a low resistor in series; on the user side the phenomena are correct, but on the wall plug side (as well as by feeling the temperature) we can detect that the model does not correspond to reality.

[...] There is its called fields. Or if you want to stay strictly classical the distribution and pressure influence of the standard model of particles.

[..] More specifically that cannot be modelled using fields?

I already linked once or twice to the "mother" thread in which I elaborated on that question (as well as what we mean with "physical properties" etc), which belongs to the topic there, starting from:

http://www.scienceforums.net/topic/97105-is-space-time-a-physical-entity-or-a-mathematical-model/page-11#entry944692

Again once more: this topic is the discussion-in-part of models that pretend to fill that gap. [edit:] and of course, if you can explain such things as time dilation by means of fields in physically empty space, please show us by giving a corresponding "Field interpretation" of the car example, explaining the the propagation of light as well as the relative and absolute aspects of time dilation.

I have to ask. I know your familiar with SR. How familiar are you with the Einstein field equations?

Good question. And as this thread is not particularly meant to answer my questions: How about the others who participate in this discussion, how well do you know GR?

As for myself, I only know the Einstein field equations superficially (including some nice explanation by Baez). However I have a good understanding of Einstein's equivalence principle and the low field effects on Earth.

In contrast to the flowing river model of space, Einstein obviously had in mind a non-flowing improvement to Lorentz's model [edit: added emphasis):

What is fundamentally new in the ether of the general theory of relativity as opposed to the ether of Lorentz consists in this, that the state of the former is at every place determined by connections with the matter and the state of the ether in neighbouring places, which are amenable to law in the form of differential equations; whereas the state of the Lorentzian ether in the absence of electromagnetic fields is conditioned by nothing outside itself, and is everywhere the same. The ether of the general theory of relativity is transmuted conceptually into the ether of Lorentz if we substitute constants for the functions of space which describe the former, disregarding the causes which condition its state.

Edited by Tim88

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Ok the main reason I asked on GR is that using the EFE you can model any dynamic you want. That is the power of those equations.

That is demonstrated in those articles. The equations used to model Ether for example. May contain a flow but the line element can be modified for static dynamics. (no flow).

The other reason I asked on the EFE was to find how familiar you were with the hydrodynamic aspects of the stress tensor.

the conditions where SR HOLDS true in regards to the weak equivalence principle

I shouldn't need to go through several lengthy threads to get a clear answer on this.... A detail one needs to recognize is both Lorentz and Maxwell had the same limitation. They only knew about 3 to 4 particles at best. Field theory, the EFE came later including our current understanding of particles.

Wave-particle duality wasn't really understood. So if Lorentz followed the idea that particles were like little matter bullets. Ie planets and suns, then he will try to model such. As you've read several articles specifically on Lorentz Ether. You probably came across his problems with electron contraction. His analysis never included the wavelength of the electron. His formulas (as presented then, didn't work for gravitational doppler.) At least according to several peer review articles on the subject.

lets examine a logic problem with Ether. Lets use properties. Static field, fermionic (meaning were dealing with something that takes up space) aka Pauli exclusion principle.

Ok first question. What does the Ether couple with ? Good luck on that question. As far as I can tell it doesn't couple to any other field. You discounted coupling to gravity by turning down models that state that Ether flows towards mass, like any other particle Assuming it doesn't couple with any other field or any matter fields then there no way to measure or identify it....

If it doesn't couple to any matter fields or force fields. It cannot contribute to mass in any way. After all mass comes from binding energy. So if it doesn't contribute to mass, it doesn't couple to any force fields or matter fields.

People that typically defend Ether theories. Typically have the Bullet visualization of particles. Yet a particle in modern times is a field excitation... It has a wavelength and point-like properties of no discernable volume. Lorentz Ether tackled the electron as though it had a length to contract. This is another error that we recognize in modern physics. The nature of the electron wasn't known then. The length contraction though does help on wavelength. Thankfully...

Ok assuming Lorentz Ether is a matter field (as of yet undetected) It is subject to medium dragging properties. Unless it doesn't couple to anything (hence useless).

Why can't we detect this Ether?

It doesn't matter what type of Ether were dealing with. It could be luminiferous Ether, covarient Ether (category Lorentz Ether falls under) or any other form of Ether. If it is a medium it must obey all medium property rules. Ie Drag

(as far these models are concerned, have you ever studied the math itself. Not the accompanying explanations?)

Have you identified why Block is different than evolving block? Have you connected the symmetry vs assymetry relations? Have you correlated why the terms Reversible and irreversible are important considerations? Ajb didn't have any difficulty understanding its importance. He even described a methodology to aid the block models maintain the deterministic aspects. (these techniques get incorperated into the evolving block.

Edit: To answer your question on how much I understand GR. Enough to get me a master degree in philosophies of Cosmology and a minor degree in particle physics, which I am currently trying to get to Masters.

My focus being Higgs inflation in the SO (10) minimal symmetric standard model.

lol might explain my interest in thermodynamics

(its fundamental in GR, Cosmology and even particle physics)Lets add a statement. In my opinion, "evolving Block" is a better model reality than "Block".

The EFE is a better model of reality than Ether based theories. On the QM side, loop quantum cosmology is excellent and I consider a good competition to LCDM

Lorentz made important modifications that led to new unheard of predictions. The tests designed to verify these new predictions

Perhaps you misunderstood the purpose of this topic? However I agree that the River model was an interesting one to mention as an example of another model that emulates many of the phenomena while at the same time being incorrect; I did not fully read these articles although I read some in the past. It reminds me of the fact that we can successfully model an ecological high quality voltage source as a current source with a low resistor in series; on the user side the phenomena are correct, but on the wall plug side (as well as by feeling the temperature) we can detect that the model does not correspond to reality.

I already linked once or twice to the "mother" thread in which I elaborated on that question (as well as what we mean with "physical properties" etc), which belongs to the topic there, starting from:

http://www.scienceforums.net/topic/97105-is-space-time-a-physical-entity-or-a-mathematical-model/page-11#entry944692

In contrast to the flowing river model of space, Einstein obviously had in mind a non-flowing improvement to Lorentz's model [edit: added emphasis):

Not accurate, Einstein made sure the EFE was reducible to SR. The weak equivalence principle (particles in a box) is only a minute slice of spacetime where two particles will maintain parallel transport.

Ie they fall perfectly straight down.

However if you increase the initial seperation distance between the two test particles. When they fall to center of mass. They will fall in two identical diagional paths. Forming an inverted triangle. (This is where Principle of Covariance comes in).

( little hint if you can't model a static solution, your flowing solution isn't complete. Modelling the static first gives you your symmetry baseline. Then you add the flow.) In SR. $g_{\mu\nu}=\eta_{\mu\nu}+h_{\mu\nu}$ first $\eta$ is your reference frame (cartesian)static. Your flow gets added under the h tensor.

So under the River model $\eta$ frames flow according to h tensor. If the first order vector under h is zero. There is no flow of frames under eta. Direction of vectors determine your covariant and contravariant rotations.

In the Lorentz guage you have 3 rotations and 3 boosts. That unfortunately would take too long to detail.

I already mentioned as part of the Lorentz ether explanation of SR that the (special) relativity principle can be derived from the conservation laws, based on the Lorentz ether (if you like I can give a reference to a paper in which the derivation is done). It's immediately understood if one realizes that the Lorentz ether mathematically corresponds to labeling an unknown frame "the Lorentz ether". So that's another misunderstanding.

"Field interpretation" of the car example, explaining the the propagation of light as well as the relative and absolute aspects of time dilation.

whereas the state of the Lorentzian ether in the absence of electromagnetic fields is conditioned by nothing outside itself, and is everywhere the same.[/i]

Easily done for the field. After all SR is modelled under a field...(little pressed for time, but I'll keep it as simple as possible)

Yes I would like to see your reference paper. Not that I disagree with the mathematical methodoly used in the reference. Nor your above descriptive. It will aid communication. It would also save time

A related example of a field that was modelled and at one time ignored was The higgs field itself. The difference is the Higgs field is detectable. Via the ptedicted interactions we could estimate the mass of the Higgs.

This isn't true in Lorentz Ether which under GR is considered undetectable. Hence of no measurable influence. Hence not needed. It doesn't do anything....

To put simply when your modelling velocity to correlate to time dilation. If it doesn't have any influence on the four momentum or velocity. Its useless in SR..or GR. pointless to add it to the transformation equations.

As it has no influence under SR metrics. What is the point of using it to describe the car scenario above?

Edited by Mordred

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Maxwell wisely made no mention of an ether in his EM theory, as the math worked without it and he could not define it. Einstein made no mention of any form of ether in relativity theory, as the math worked without it and he could not define it. However, this does not lead that an underlying ether does not exist. It's going to take a very special individual to give ether a great deal of thought, before any existent ether's inherent yet-unknown properties may be defined, and would need to be verifiable by test. I wonder whether an ether may be logically deduced (inferred) to exist (someday), even though it is not determinable directly by test. Certainly, we're going to have to learn something NEW first to ever cross that bridge.

Matter, gravity, and light are energy. If they are all of the very medium, then energy is any variation or configuration of the medium within itself, and no matter whether it is immovable or not. If so, then the properties of any form of energy constitute a subset of the properties of any underlying ether. In such case, we see space and time when we see any form of energy, that is, we see (or feel) it when it exists in the required configuration for detection. Certainly, empty space is transparent and intangible. However, space and time are measurable. Unfortunately, the measure of space and time cannot reveal an underlying ether. I venture, that only quantum mechanics can reveal required properties of an underlying medium. And, I would guess that space and time alone will be insufficient, even at that level. Anyone who claims to have modeled an underlying ether using only space and time, others will argue that it is only a spacetime field and not an ether that gives rise to space and time. One might ask, what is the difference?

I do not understand why the ether must even possess a master frame. Why not approach an ether assuming that motion is meaningless wrt it? I mean, motion is meaningless wrt space-time. If spacetime is all there is, then spacetime is simply curved unto itself. If spacetime is the variation of an ether within itself, it seems impossible IMO to prove it exists by the measure of space and time alone. Something other than space and time seems required, to prove its existence. QM will likely have to prove an ether, IMO.

Mordred, I must say, there is a nice appeal to the quantum geometrodynamics you mentioned. Time arising from introduction of matter waves. Does this model "model space after the bang but before matter came to be"? Does it help explain the double slit experiment any? Is it applicable to M-theory?

Best regards,

Celeritas

Edited by Celeritas

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Excellent post above.

Quantum geometrodynamics via Wheeler Dewitt primarily dealt with gravity. However under the quantum cosmology aspects the BB is described. Though didn't solve the singularity problem.

LQC which is also a canonical gravity solution was able to do so. LQC however is signicantly different than geometrodynamics even though at first glance appear related. LQC attempts to fix problems in the latter.

There is another class of geometrodynamics under topological geometrodynamics. classical and quantum dynamics.

The last two detail the various gauge theories (electromagnetic,weak,strong etc). the latter uses spinors and twistors.

Here is an intro to quantum geometrodynamics. You can see there is 3 time treatments. time before quantization, time after quantization and no time.

It is a dissertation paper by Micheal Cooke.

Here is an intro to LQC.

http://arxiv.org/abs/1201.4598 "Introduction to Loop Quantum Cosmology by Abhay Ashtekar

An overview of topological geometrodynamics. (800+pages lol)

The dissertation I'm reading would fall under topological geometrodynamics but his paper is primarily the QM side. As I mentioned though I'm not an expert at geometrodynamics though I am familiar with it. (I study it off and on as time and interest allows):gotta hate RL.

PS my wife hates my textbook collection. 100+ textbooks takes up too much room lol

Edited by Mordred

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With a little rearranging:

Ok the main reason I asked on GR is that using the EFE you can model any dynamic you want. That is the power of those equations.
That is demonstrated in those articles. The equations used to model Ether for example. May contain a flow but the line element can be modified for static dynamics. (no flow).
The other reason I asked on the EFE was to find how familiar you were with the hydrodynamic aspects of the stress tensor.
the conditions where SR HOLDS true in regards to the weak equivalence principle

OK. Obviously the EFE are in themselves not limiting, just as in my electrical example there is partial equivalence between circuits with a current source and with a voltage source.

I shouldn't need to go through several lengthy threads to get a clear answer on this.... A detail one needs to recognize is both Lorentz and Maxwell had the same limitation. They only knew about 3 to 4 particles at best. Field theory, the EFE came later including our current understanding of particles.
Wave-particle duality wasn't really understood. So if Lorentz followed the idea that particles were like little matter bullets. Ie planets and suns, then he will try to model such. As you've read several articles specifically on Lorentz Ether. You probably came across his problems with electron contraction. His analysis never included the wavelength of the electron. His formulas (as presented then, didn't work for gravitational doppler.) At least according to several peer review articles on the subject. [..]

Lorentz Ether tackled the electron as though it had a length to contract. This is another error that we recognize in modern physics. The nature of the electron wasn't known then. The length contraction though does help on wavelength. Thankfully...

It's unclear what your aim was with those statements. The correct prediction of electron acceleration was done despite the fact that Lorentz and Einstein had the limitation that they did not know about the wave nature of the electron. While giving a little context, such historical facts have no direct bearing on the topic.

To answer your question on how much I understand GR. Enough to get me a master degree in philosophies of Cosmology and a minor degree in particle physics, which I am currently trying to get to Masters. [..]

It was understood that you have GR expertise.
My question was aimed at the others who participate in this thread. This philosophical discussion is intended to be understandable for non-experts, but it would be too limiting to only cover SR effects.

[..] Ok first question. What does the Ether couple with ? Good luck on that question. As far as I can tell it doesn't couple to any other field. [..]

[..] In my opinion, "evolving Block" is a better model reality than "Block".
The EFE is a better model of reality than Ether based theories. On the QM side, loop quantum cosmology is excellent and I consider a good competition to LCDM
[..] Yes I would like to see your reference paper. Not that I disagree with the mathematical methodoly used in the reference. Nor your above descriptive. It will aid communication. It would also save time

A related example of a field that was modelled and at one time ignored was The higgs field itself. The difference is the Higgs field is detectable. Via the ptedicted interactions we could estimate the mass of the Higgs.

This isn't true in Lorentz Ether which under GR is considered undetectable. Hence of no measurable influence. Hence not needed. It doesn't do anything....

To put simply when your modelling velocity to correlate to time dilation. If it doesn't have any influence on the four momentum or velocity. Its useless in SR..or GR. pointless to add it to the transformation equations.

As it has no influence under SR metrics. What is the point of using it to describe the car scenario above?

I cited Einstein's clarification of the coupling in the post to which you replied here; apparently you overlooked it.

And it sounds as if you still don't understand the topic of this discussion (as well as the topic of discussion of the thread from which this is a spin-off).
The models that we compare here are not supposed to have any "influence under SR metrics"; they are competing models for causing SR metrics - and except maybe in Harry Potter, mathematical equations cannot cause physical phenomena.

Thus, if your "fields" are supposed to cause SR metrics, please demonstrate how they can do this (and thus purport to explain SR) by means of the car example at hand.

I found the paper "Derivation of the Lorentz transformations" (which imply the PoR) from the conservation laws: Ives, Phil. Mag.36, 1945

http://www.tandfonline.com/doi/abs/10.1080/14786444508520921?queryID=%24%7BresultBean.queryID%7D

It should be noted that in that derivation Maxwell's laws are assumed as well. Relevant for this topic is the claim of improved physical understanding in the conclusion:

The indeterminancies and impotences by which the "Restricted Theory of Relativity" has been widely publicized - such as the impossibility of detecting uniform motion with respect to the ether, the constancy of the measured value of the velocity of light, the elusiveness of the establishment of exact simultaneity at different points, the indeterminancy of relative velocities except when they are equal - all follow as consequences of our resolution of the apparent conflict between the laws of conservation of energy and momentum on the one hand and the laws of light propagation on the other, our resolution being in favour of the conservation laws. - Ives, Phil. Mag. 1945

Anyway, despite your claim that you don't need it, you seem to favour the evolving block universe. If so, can you answer my questions about block universe in post #84?

[edit:] And please clarify how according to you, block universe doesn't survive under robust examination.

Maxwell wisely made no mention of an ether in his EM theory, as the math worked without it and he could not define it. Einstein made no mention of any form of ether in relativity theory, as the math worked without it and he could not define it. However, this does not lead that an underlying ether does not exist. It's going to take a very special individual to give ether a great deal of thought, before any existent ether's inherent yet-unknown properties may be defined, and would need to be verifiable by test. I wonder whether an ether may be logically deduced (inferred) to exist (someday), even though it is not determinable directly by test. Certainly, we're going to have to learn something NEW first to ever cross that bridge.

Matter, gravity, and light are energy. If they are all of the very medium, then energy is any variation or configuration of the medium within itself, and no matter whether it is immovable or not. If so, then the properties of any form of energy constitute a subset of the properties of any underlying ether. In such case, we see space and time when we see any form of energy, that is, we see (or feel) it when it exists in the required configuration for detection. Certainly, empty space is transparent and intangible. However, space and time are measurable. Unfortunately, the measure of space and time cannot reveal an underlying ether. I venture, that only quantum mechanics can reveal required properties of an underlying medium. And, I would guess that space and time alone will be insufficient, even at that level.

As you could have read in this very thread, Einstein did make mention of Lorentz's ether in relativity theory. As for Maxwell, he certainly did mention it too. Please add those opinions to the mother thread where the discussion takes place if there is more to space than just mathematical space. In this spin-off we compare the explanatory power of competing models.

Anyone who claims to have modeled an underlying ether using only space and time, others will argue that it is only a spacetime field and not an ether that gives rise to space and time. One might ask, what is the difference?

The philosophical differences are huge. Maybe you can help with my questions about the block universe model ("spacetime field") in post #84?

[..].Regarding Lorentz LET,

Just a side note: Probably you don't mean the "Lorentz Electron Theory" about which he published, but "Lorentz Ether Theory" of which he may never have have heard.

[..] When considering LET, it's easier IMO to [..] start from Einstein's SR and work backwards to Lorentz ether. The mistake IMO, was their ad-hoc assumptions to force fit an ether related physical-source to obtain clearly required covariant solns (based on Euler rotations). IOW, I'm suggesting that the source of LET's relativistic effects is caused by the relative measure of space and time per differing POVs (as in SR), except that a master frame exists. And remember, SR said any absolute frame was superfluous to the solns, not that they did not exist. Of course, Einstein assumed any inertial frame was TRUE as a starting point. To extend SR to LET, one simply presumes that there exists one inertial frame that in fact measures what IS TRUE, and all others are merely APPARENT (untrue).

I have no idea what "force-fitting" you imagine, but your understanding of the causal meaning of absolute space is certainly correct. I hoped to have sufficiently clarified that with the car example.

YET, since it is quite impossible to prove a master LET frame via light signals, one can never ever know which inertial frame it is even if it does exist (Occam's Razor says ignore that model). Then one asks, if you guessed right about the master frame, [..]

Following your argumentation, Occam's razor would have said "ignore the atomic model" to Boltzmann (see post #20). And why would anyone need to "guess the master frame"?? Indeed, why would Boltzmann have needed to see atoms?? But that's again continuing the discussion that belongs in the other thread...

[..] does it make any difference at all, far as spacetime solns are concerned? The answer to this point, is NO. So ultimately, I'm saying that LET could be SR with the exception of "only the master frame measures what is true (eg what is simultaneous, what is contracted, isotropic c, etc)", versus "each frame measures what is true". IOW, LET without that ad-hoc'isms. Had Lorentz just assumed (as Einstein) that different frames measure differently, his ad-hoc'ities were never required, and he could have kept his presumption of a master ether frame. However, what good is a physical model that cannot be proven? Not that I favor LET, as "I favor SR". Yet, SR "assumes" the 1-ways speed of light is c, which is nothing but a convention. While I cannot prove it, I sure would hope Einstein's convention matches reality, because of the simplicity and elegance of it.

[..]

I do not understand why the ether must even possess a master frame. Why not approach an ether assuming that motion is meaningless wrt it? I mean, motion is meaningless wrt space-time.[..]

Now you got me really puzzled!

Motion is embedded in space-time as trajectories through space-time. And how can an entity cause effects from motion if motion is meaningless wrt it??

Concerning the 1-way speed of light convention, that originated with Poincare as it was the practical thing to do. Further:

- Einstein never pretended that his convention matches reality

- The concept that the 1-way speed of light is "truly c", does not match any model of reality that I know of. I suspect that it may be easy to disprove. [edit:] it's even in direct conflict with the PoR, if I correctly understand what you mean here.

If you think that it can work (or that it is part of Minkowski block universe model), please clarify how by means of the car example, thanks!

PS. Much so-called "ad-hoc"-ness of successful theories is mere mud-throwing due to lack of scientific arguments.

Best regards,

Tim88

Edited by Tim88

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Tim88 post#91

As you could have read in this very thread, Einstein did make mention of Lorentz's ether in relativity theory

Pity your observation contradicts the associated quote.

Celeritas post#89

Einstein made no mention of any form of ether in relativity theory, as the math worked without it and he could not define it.

I'm not sure whether Maxwell discussed the Aether or not, I'm sure he would have thought about it.

He did, however, produce a hexagon cell structure proposal for space to discuss the propagation of EM radiation through the vacuum.

I posted a reference to the source of that a couple of years ago here.

I will try to find it.

Edited by studiot

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The issue of 'equal footing' is interesting since whilst you can directly plot distance, you cannot plot time.

The method of overcoming this is, of course, to multiply time by a velocity to obtain a distance.

Thus we get to 'ct' as the fourth axis.

However this has some disadvantages, not the least being that there are now two versions of 'spacetime'

one with four distance axes and one with three distance axes and one time axis.

Another disadvantage is that euclidian distance is no longer the sum of the squares of the projections on the axes but has a negative sign in the equation.

This latter can be overcome by the Argand view of the world and multiplying time by ic instead of c and considering the the fourth axis as a rotation from the others.

What implications this has for separation of time and space I'm not sure.

I understand Minkowski (though I don't have original references) originally proposed his 4D world in Argand format since there are only 3 (known) spatial axes not four, so a fourth one must be imaginary.

Using tau = ict allows the standard metric and works well when moving from relativistic kinematics to relativistic mechanics.

Where were you all this time? You could have enlightened an old thread fantastically. See here if you're interested.

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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....

Edited by Mordred

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Where were you all this time? You could have enlightened an old thread fantastically. See here if you're interested.

Well that question you posed then was a couple of years before my time here but thank you for bringing it to my attention.

If you are interested, there is a good presentation and development of this view in the book by Wilson that I posted an extract from in post#34 here and that Tim likes so much (actually I do too) even though that extract ends by declaring the Aether "superfluous"

The author, BTW, was Professor of Physics at Rice in Houston, Texas.

Another quote that might tickle your fancy comes from Eddington (Sir A)

The law of gravitation is not a law in that it restricts the possible behaviour of the substratum of the world; it is merely the definition of a vacuum. We need not regard matter as a foreign entity causing a disturbance in the gravitational field; the disturbance is matter. In the same way we do not regard light as an intruder in the electromagnetic field, causing the electromagnetic force to oscillate along its path; the oscillations constitute the light. Nor is heat a fluid causing agitation of the molecules of the body; the agitation is the heat.

Edit: The explanation you received from DH in your old thread about the lightsphere is essentially the geometric method I offered in post#46 and rejected by Tim. The earliest reference to this construction was I can find was by Russell.

Edited by studiot

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Tim are you not aware that when you use SR you are already using classical field equations? The minute you add coordinate mapping your mapping a field.
The mathematics of symmetry groups just wasn't available when SR, Minkowskii and Einstein first proposed their models. The Field treatments were formalized later under symmetry groups. Block/evolving block doesn't add any field or particles.
Lorentz ether does. It adds a substrate field of ether. (motionless matter) One that mysteriously has zero influence on anything.
A reference frame is just a map of a field measured by an observer. A field is simply a collection of objects/events
The equations you guys are using for time dilation/length contraction are just transformation equations between reference frames. Those transforms fall into the group $h_{\mu\nu}$ the $\eta_{\mu\nu}$ tells us the geometry of the field is approximately Euclidean.

(ct,x,y,z) is a field coordinate map. Your already modelling the car in field theory. So other than showing how to derive the time dilation formula and contraction formula....However you already know how to derive gravitational time dilation/length contraction etc. (according to the statement "I understand SR")
You guys have already shown the car example according to the EFE. SR is a subgroup of the EFE equations. falls under the Lorentz group/Poisson group.

Lets play Quantify Lorentz Ether properties. Assume it is static and doesn't interact. considered a medium. What properties can we discern just using the above statement ?
1) comrised of fermionic particles (matter)
2) static follows spin statistics zero. So spin zero.
3) has no quage bosons, no mediator particles. (non interacting) (except maybe to itself, impossible to know )
This field will have geometry (x,y,z) it doesn't interact so it is invariant. All observers will measure (if possible lol) it the same.
Question 2 if its non interacting, why include it? It has no effect on the kinematic motion of any other particle fields. Has no influence on time dilation or length contraction.
More importantly as its non interacting there is no possible means to measure it. It has no influence.

useless to include it into SR

PS it doesn't make any difference if Ether flows or not. There is no known interaction with any other field or particle.
Lets tackle this with an analogy.

A neutrino is weakly interactive. It can literally cross a thousand light years of solid lead without a single interaction.
For all intensive purposes the lead doesn't exist when modelling the path of the Neutrino. As there is no lead interaction it has zero influence on the neutrino path. (pointless to include the lead, no effect on neutrino path) Yes there definitely was a medium there but it has zero effect....zero influence upon path measurement.

Anyways lets compare electromagnetism to gravity shall we...

first define Newtonian geometry.

$ds^2=dx^2+dx^2+dy^2+dz^2$

under rigid coordinate system transform rules $\acute{t}=t, \acute{x}=x$ time isn't a factor here... observer in primed frame is moving in the x direction at velocity v

When you add time to the above you must preserve the Galilean transformations above.

$ds^2=\eta_{ij}dx^idj^j=-dt^2+dx^2+dy^2+dz^2$

transform rules

$t^2=\frac{t-vx}{\sqrt{1-v^2}}$,$x^2=\frac{x-vt}{\sqrt{1-v^2}}$

Maxwell equations.

$\bigtriangledown\bullet\overrightarrow{B}=0$

$\bigtriangledown*\overrightarrow{E}+\frac{\partial\overrightarrow{B}}{\partial t}$

$\bigtriangledown\bullet\overrightarrow{E}=\rho$

$\bigtriangledown*\overrightarrow{B}-\frac{\partial\overrightarrow{E}}{\partial t=\overrightarrow{J}}$

E and B are the electric field and magnetic field, J is current per area,(source current),rho is the charge per volume.

using Minkowskii coordinates we can replace the spatial vector potential A and scalar potential $\phi$ with the single 4 vector component. $A^\mu=(\phi,A^1,A^2,A^3)$ through a lengthy procedure $F_{\mu\nu}=\partial_\mu A_\nu-\partial_\nu A_\mu$ the field strength tensor.

Please note no Ether required yet, nor needed to derive the above equations...use of rho is essentially a vacuum solution, the difference is you have a directional component.

In relativity we use rho as energy density per volume ( scalar) though you can treat it as charge for flows. Anyways I'm not going to detail all of Minkowskii or Maxwell. I'm only interested atm at the stress energy momentum tensor compared to field strength tensor

First lets establish dV, consider some infinitesemal volume of material of 3 dimensional space (for simplicity a rectangle)

there are two types of forces that can affect DV -volume forces and surface forces. Both above are volume forces.

$dF_{grav}=\rho_mgdV$ where $\rho_m$is the volume mass density. (3d metric for the derivitave)

$dF_{electric}=\rho_eEdV$

where $\rho_e$ is volume charge density

. Surface forces act upon a particular surface. One example being pressure (loosely, gets tricky on adiabatic flows etc) not important atm...neither is pressure shear.

the importance is in both cases we just described the Space described by the math....identically in both cases. Without using ether or block universe.

$dF_{grav}=\rho_mgdV$

$dF_{electric}=\rho_eEdV$

Title of this thread. "Models for making sense of relativity - physical space vs physical spacetime"

DONE EFE example with Maxwell comparision. When you apply the x coordinate tranforms the mass density changes as the volume of dV changes. Pretty straightforward and easy to understand. Each frame in Minkowskii is Euclidean so in each frame the last two formulas hold true. When you compare frames you transform the volume of DV.

What could be easier to explain?

Edited by Mordred

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Evolving Block Universe: isn't that inserting time twice? once for for the T axis, and once for the "evolving" thing?

I've never quite understood the "no time" arguments, even though I understand the block universe model. While the worldlines of a block universe are static in 4-space, this does not prevent the advancement of lines-of-simultaneity along those worldlines. That is, there could be "an activity" that exists within an otherwise static block universe. IOWs, even in the Minkowski 4-space model where time is a 4th spatial axis, time still advances along any worldline at the rate of proper time. No matter what rate one might imagine lines-of-simultaneity to advance, all events still occur at the same predictable clock readouts, regardless. So the rate of proper-time seems unrelated to worldlines or spacetime solns. Given we experience time's passage, the block universe must in some way comply IMO.

Best regards,

Celeritas

Here also there is distinct attempt to introduce a rate of things that happen, like a time inside time.

As if the 4D static block universe explained nothing about the passage of time.

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

And also this important point raised by Studiot; the T time has been subjected to mathematical transformations. In the diagrams, it is not T, but cT, eventually icT if I understand clearly.

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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.

[..]

If block adds nothing as you think, then how can there be a problem with it? If it adds nothing, then the claims about block universe were just meaningless - and you cannot kill it under robust examination, as you pretended! But I still look forward to see your debunking of it.

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Why don't you actually study block universe? What is the equation for block universe? It does have one...

Maybe you should stop and actually study the model.

go ahead challenge me post the math for block with SR.

Edited by Mordred

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[..]

the importance is in both cases we just described the Space described by the math....identically in both cases. Without using ether or block universe.

[..]

Regretfully all of it totally missed the point: you are here obviously arguing that there is no need to assume anything but mathematical spacetime. That is not the topic here, and none of it even addresses the arguments given in the thread on that topic, where your discussion belongs. Please stop posting off topic posts. I already told you several times.

[..] What is the equation for block universe? It does have one...

Maybe you should stop and actually study the model.

go ahead challenge me post the math for block with SR.

No, stop hijacking this discussion.

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