we dont know enough (at least I dont) to really answer this question yet.

the aether connot be discarded , even empty space is not totally empty, and

after dirac one wonders if all the negative energy levels are full to the hilt with

particles and energy.

gravity waves can still be handled for now by existing theory.

particles predicted by some sort of  exitations in hilbert space for example is

is a tempting idea, but this means some sort of further extension of the quantum

theory yet,

Only if the vacuum energy travels at light speed in all directions at the same time.

Jerry, Your answer seems to imply that the current model of the universe gives a good explanation for the constant speed of light, It is easy to state mathematically that photons propagate at a constant speed of light in all frames of reference. However, is this conceptually understandable? If vacuum energy is a sea of Planck length vacuum fluctuations oscillating at Planck frequency, then this incorporates the speed of light in all directions and partly achieves your goal. However, the complete explanation that achieves all the necessary Lorentz transformations is much more complicated. What is your model for achieving a constant speed of light?  

Dear John, you ask

==> "The standard model is a field theory where all fundamental particles are considered “excitations” of their respective fields. For example, there is an electron field, a muon field and a Higgs field. Do these fields physically exist in spacetime? If so, can they be described physically and collectively described as a relativistic aether?"

I propose an improvement of this question: "can their ZERO-occupation number be described physically and collectively as a relativistic aether?"

The answer seems to be negative. The quantum field theory (QFT) says that the zero-occupation number of each such field has an energy ½ħω and calculi show that the total energy resulting from these zero-fields is by a huge order of magnitude than the general relativity requires.

I wonder whether it can't be that the aether is that "dark matter" discovered in the last time. But, could the aether have an observable energy?

Sofia,  Your question is forcing me to reveal and defend my model of the universe. Your question is also revealing that you believe it is impossible for a relativistic aether to have energy density in excess of the "critical" energy density of the universe. In other words, relativistic aether can have energy density of about 10-9 J/m3, but not 10113 J/m3 which is roughly Planck energy density. 

I am working on a paper on this subject and I do make the case that Planck length vacuum fluctuations at Planck frequency exist in the vacuum and give the vacuum its constants of G, c and h bar. The equations of general relativity are usually interpreted as forbidding this large vacuum energy density, but the equations themselves do not forbid the existence of a form of energy that does not exert gravity.  For example, the average energy density of electron/positron virtual particles greatly exceeds the critical energy density of the universe. However, we rationalize that this is a form of energy that does not count towards the total. I maintain that vacuum fluctuations that do not have quantized angular momentum are fundamentally different than the fermions and bosons that generate gravity.  These vacuum fluctuations are between positive and negative curvatures of spacetime (gravity and anti-gravity spacetime curvature). This cancels gravitational effects.  This missing component in out model of the universe causes many of the mysteries we encounter in physics today.  I can send a draft of the paper to anyone that is interested, but I am not ready to post it yet. 

It is less an aether and more an absolute space-time à la Newton.

It's not the light and the electromagnetic waves that need the aether, it's the electrostatic, magnetostatic and gravitational field that need an aether to store their potetial energies. And the difference in range between these fields require difference in the properties of the aether.

Unconventional/Relativity

@Thierry De Mees

==> "aren't  light and the electromagnetic waves made by continuously alternating electrostatic, magnetostatic, gravitational and gravitomagnetic fields?"

The basic particle of the electromagnetic wave is the photon. It has both electric and magnetic field. But it has no graviton in it, at least the standard model does not say such a thing. 

But the problem was different: the photon is believed as not needing a medium for propagation, an aether. I repeat, so it is believed today. But the electrostatic field has to be stored somewhere. ACTION-AT-A-DISTANCE is not accepted, s.t. we have to admit that the vacuum is not "nothing", that it is a medium that gets polarized and in this way it forwards the static field.

My suggestion: Whenever, within a given space, we observe phenomena like pressure, characteristic velocity of propagation, waves and related ones, that space physically behaves as being filled with some kind of medium even if there are no obvious material particles involved. Whether we call it "aether" or "vacuum" should be of minor importance.

Unconventional/Relativity

"could the aether have an observable energy?"

Dear Sofia,

we know, at least, that static magnetic fields may exert considerable field pressure within a gap as technically exploited, e.g., for non-contacting support of heavy transport vehicles and rotating machinery, and pressure of whatever kind has the physical dimension of energy density. So at field pressure p every piece of volume dV will contain an amount of energy dE = p*dV.

@Johan K. Fremerey

Dear Johan,

You wrote

==> "static magnetic fields may exert considerable field pressure within a gap as technically exploited, e.g., for non-contacting support of heavy transport vehicles and rotating machinery,"

What you mean by "within a gap"?

I know that a magnetic field can attract a piece of iron when both are in vacuum. But I have a problem with your formula dE = p*dV. You see, when a field does a mechanical work, potential energy of the field transforms into mechanical energy. The field looses that amount of energy. If the magnetic field moves a coin of Fe of surface S along a distance dx, the kinetic evergy of the coin increases by dEK = p*S*dx = p*dV, where dV = S*dx.

So, do you infer that in the volume dV was confined an amount dE of potential energy? You see, behind the coin there is stil magnetic field, storing magnetic energy.

"What you mean by "within a gap"?"

Dear Sofia,

in bearing technology a gap is defined between a moving and a stationary part. The bearing gap is usually filled with rolling elements for support of a movable load, in particular, with ball bearings for support of rotating machinery, or wheels under a railway train.

In a magnetic bearing the gap in place of roller elements contains a static magnetic field which by associated field pressure just provides a steady, non-contacting weight balance for a movable load without being transformed into mechanical work. You will experience that sort of pressure when facing permanent magnets in a repulsive configuration.  

Dear Johan,

I do not understand why you consider magnetic field, in particular the strong repulsion or strong attraction to be used for validating aether existence

@Albert Roseiro

Dear Albert, how do you expect Johan to reply? Your question contains a common mistake - people frequently say "I don't understand" without giving additional information. "I don't understand" has a too much broad scope. For helping Johan to answer, you have to limit the scope of the question and tell what displeases you with choosing the magnetic field, what seems to you unfit, or what you would choose alternatively and why, etc.

Best regards! 

"I do not understand why you consider magnetic field ..."

Dear Albert,

please have a look at my previous posts. 

a magnetic field would be easy to detect, it you introduce a diamagnetic material or

a superconducting material where there is a magnetic field, you have repulsion.

detecting a gravitational field is a bit different

you could say that a test mass is attracted.

nothing is known to definitely detect aether, one of the problems is that

supposedly it is everywhere.

Vacuum and aeither seem to mutually exclusive media. In my theory of Absolute Genesis, these may point to zero point limit which produces absolute vacuum!! Mathematically we shall use one or other to develop a unified field theory. Then one may use logic of complement to relate them. 

Using particle matter as condensed field may take care of the separate considerations of vacuum and aether. I see a problem of algebraic functionality especially with extending General Theory of Relativity. Special Theory E=Mc**2 with General Theory field functional equations may provide a mixture of equations (non-function) along with functions. Presently thinking will be that a possible algorithm will help to unify towards Grand Unified Theory of Everything. In this respect, relativistic aether may be helpful in space time mathematical quantifications.

Dear Johan,

I did read your previous posts but do not understand what you're trying to convey: the real question with proving by an experiment if aether exists was never solved so far by anybody including the use of magnetic experiments.  

The magnetic effect you describes can work within a vacuum chamber experiment but same with electrostatic effect (attraction, repulsion) or electromagnetic wave (radio propagation) or gravitation (only attraction). So either distant mass effect, distant electrostatic effect, distant magnetic effect or radio-transmission effect requires a support or medium to manifest (ether theory) or they can really propagate through matter-free (vacuum).

Why would you consider magnetic experiment to help determine the aether exists ?

"I did read your previous posts but do not understand what you're trying to convey"

Dear Albert,

I essentially suggest that pressure, propagation speed, waves etc. are phenomena typically attributed to some kind of medium rather than to an absolutely void space.

P.S. - So you may regard the appearance of above mentioned phenomena as a direct proof of the existence of such medium.

"I essentially suggest that pressure, propagation speed, waves etc. are phenomena typically attributed to some kind of medium rather than to an absolutely void space."

Dear Johan,

I do agree with this statement as a radio engineer but the thing is how to establish a proof and experiment to validate the existence of this medium. We've been looking after this for more than 100 years, well you know the story....

One reason I was intrigued by your specific exemple of magnetism, it is true that among electromagnetic forces (electrostatic, magnetic), the magnetism is less understood.

The electrostatic has polarities, fields, monopoles whereas as of today, no magnetic monopole has been found or proven. So in a way, we could intuit the main show stopper of unified theory are gravitation and magnets belonging to the distant action force family, some sort of generalized electromagnetic wave but that is my personal opinion.

On a side note, I did start very recently one simple thread to unwind what happened initially with Einstein then later...

https://www.researchgate.net/post/Einstein_Ether_and_Relativity

"how to establish a proof and experiment to validate the existence of this medium."

Dear Albert,

while editing your latest post you may have missed my above P.S. statement:

"So you may regard the appearance of above mentioned phenomena as a direct proof of the existence of such medium."

The 'empty space', 'vacuum' , 'free space' or what else name has been given has some characteristic properties that do not align with a NULL entity.

Some of them are from electromagnetic family: Copy here from https://en.wikipedia.org/wiki/Vacuum :

"

In the theory of classical electromagnetism, free space has the following properties:

• Electromagnetic radiation travels, when unobstructed, at the speed of light, the defined value 299,792,458 m/s in SI units.[30]
• The superposition principle is always exactly true.[31] For example, the electric potential generated by two charges is the simple addition of the potentials generated by each charge in isolation.
• The value of the electric field at any point around these two charges is found by calculating the vector sum of the two electric fields from each of the charges acting alone.
• The permittivity and permeability are exactly the electric constant ε0[32] and magnetic constant μ0,[33] respectively (in SI units), or exactly 1 (in Gaussian units).
• The characteristic impedance (η) equals the impedance of free space Z0 ≈ 376.73 Ω.[34]"

There also exist others.

In fact 'empty space' IS NOT EQUAL to NULL.

Very interesting question .

Einstein believed in the Ether in "some" form - me to -maybe the answer is the Vacuum in Space.

All conditions are possible in the Vacuum

Kurt Wraae

Dear users,

Everybody agrees that the vacuum has properties, the vacuum stores static fields, so it is not NULL.

Now, one more step: some people think that the vacuum is in fact a see of virtual particles. However, calculating the vacuum energty in base of this hypothesis clashes with the value obtained in base of the cosmological constant.

Then, what you think: is the vacuum a sea of virtual particles, or it is something else, yet to be discovered?

There are a lot of things that permeate all of spacetime.  For example the current model for dark energy can be interpreted as a matter field permeating the whole of spacetime with constant energy density and negative pressure.  Some suggested models for dark matter like Wave Dark Matter (i.e. scalar field dark matter) are also sort of universal fields with certain properties not unlike the quantum fields you were describing.

As a mathematician, if you wanted to collectively call all of those effects "ether," I wouldn't mind because I would know what you're talking about.

However, my understanding of the traditional definition of a medium is something that exists independently of phenomena and so would be present with or without matter.  For example, the mediums that sound propagates through, like air or water, exist with or without the sound.  So for ether to be a medium, it would need to exist with or without other forms of matter.

All of the fields you described and the ones I cited above exist because of the matter (or, for some, are the matter) and such a "medium" wouldn't be there without them.  Since this form of the "ether" couldn't exist without the phenomena, I think it would be incorrect to try to describe it as something separate like a medium.

I could maybe see collectively calling spacetime the ether since it exists independent of the stuff inside, but I don't see anything to gain by such a distinction.  It would simply be semantical at that point.  And I'm not even sure what "detecting the spacetime" would even mean beyond realizing our own existence and the universe around us.

@Alan R. Parry,

Absolutely true! If the aether exists, it exists with or without fields.

This seems to me one more argument against the hypothesis that the aether is a sea of virtual particles. I see no reason for these particles to appear "unsolicited", i.e. there where are no electric charges or magnetic fields.

According to my understanding "space" and "spacetime" are geometrical entities while "aether" is just a useful means for describing physical phenomena occuring in space.

@Johan K. Fremerey

Those aren't mutually exclusive.  Spacetime is the semi-Riemannian manifold in which we live and the geometric properties of that spacetime are what make physical phenomena (or at least gravity) behave the way they do.  It is thus a very useful means for describing physical phenomena occurring in space.

Moreover, it has all of the permeative properties that people desire of the ether and exists independently of the stuff inside it, but the thing it's missing is that it isn't made of anything physical.  It would be a 4-dimensional semi-Riemannian manifold if it had nothing in it (a.k.a Minkowski spacetime) and it would be 4-dimensional semi-Riemannian manifold if it was full of stuff, just the manifold would now be curved.

To the overall question at hand, I wanted to add:

I personally don't see any need to introduce a new independent field of stuff (is it matter? does it matter?) to house the physics when a spacetime already serves that purpose and matches observation pretty well.  If it is not supposed to be an independent matter field, then I am not sure I seen anything to gain from this seemingly semantical change.

I suppose you could argue that since matter and curvature of the spacetime are the same thing (see the Einstein Equation), that there is no need to separate the two notions.  This is probably what Einstein was referring to when he said that "fields are physical states of space" and you could call the spacetime, from this point of view, the ether.  But then nothing is "in" the ether because everything (all matter and everything else that contributes to the curving of spacetime) is actually "part" of the ether.

In either case, the analogy of the ether being a medium is still not the right picture because a medium is something independent that another phenomenon acts inside, but what I think Einstein was saying is that all of matter is the ether and, in which case, there is no independent phenomenon that acts inside that medium, since all of the phenomenon is actually the medium itself.  So is it really right to even think of it as a medium?

"This is probably what Einstein was referring to when he said that "fields are physical states of space" and you could call the spacetime, from this point of view, the ether."

Dear Alan,

we should keep in mind that Einstein's geometrical interpretation of gravitational fields, in fact, is just a proposal, while various physical phenomena, including gravitational ones, also exist in flat spacetime thus allowing to differentiate quite well between physics and geometry.

https://www.researchgate.net/project/How-many-cosmic-events-can-be-explained-by-Maxwells-equations-gravity

http://gsjournal.net/Science-Journals/Communications-Relativity%20Theory/Download/5644

Alan R. Paray wrote: “Spacetime is the semi-Riemannian manifold in which we live and the geometric properties of that spacetime are what make physical phenomena (or at least gravity) behave the way they do.”

This statement can also be reversed. Spacetime can be understood as a construction of our thinking about nature. According to that view geometry is the expression of the logic behind the spatial characteristics and relations of present-at-hand objects, and the concept of time is resulting from the fact that the phenomena behave the way they do (the world reveals itself as a temporalizing presence, phenomena have a duration, events can be dated).

In the context of that view spacetime is not an element of nature, it is an element of the way we understand and describe nature.  Therefore, it cannot play an active role in the natural phenomena and processes and it cannot possess the properties of a “relativistic aether”.

there is no perfect voidage in cosmos, therefore the old aether exists, but it must have another Name: fields. in cosmos there are 1 Atom/m³  and in Addition: Radiation, Neutrinos, photons... and that what is not known gets the Name of black/dark

Maybe in the sense that the void has some properties, may one speak of aether.

For example the concept of vacuum polarization or the possibility of destabalizing it

under strong enough eletric fields.

The ether is only a convention

”It is a convention of our inability to understand the phenomena beyond the virtual world of our ideas.” Mankind must understand that we cannot make logical extrapolations by means of elements that do not exist. We can make extrapolations only with known sequences, if we wish to observe the human logic. The virtual cannot be extrapolated in the absence of a real matter, energy or matter/energy support, as we call it in the unconventional. The only virtual world is the world of the ideas specific to the entities/universe or of their spirit, which is defined in the unconventional as a simultaneity of ideas. Let us not omit the fact that no idea can be transferred from one entity/universe to another, in the absence of the intermediary support matter/energy. The ideas are the only virtual representation of reality, whatever the nature of this reality. The ether does not exist, it is only a convention of our inability to understand the phenomena beyond the virtual world of our ideas. The ether, (as reality) represents the extrapolation, beyond ourselves or the devices that help us, (matter/energy conventional entities/universe). From nanoscience to astrophysics, nobody has discovered other forms of existence, except for matter/energy simultaneously. There is no matter in the absence of energy, such as there is no energy in the absence of matter. Our limits, or the limits of the devices that help us do not allow us the reflection of the matter support for the energy or the reflection of the energy that sustains that particular matter. There is no entity/universe that can reflect reality and its existence beyond a certain bigger or smaller limit. Starting from this interpretation and from the fact that the division of a material form or energy, (whatever the degree of division, matter or energy) is of the same matter or matter, we can make a logical extrapolation. There is no ether, such as there are no virtual particles or God in the sense of the actual interpretations, if we wish to overcome our own limitations. All these elements, (the ether, the virtual particles, or God, the entities/universe) are matter/energy simultaneously, that lie beyond our capacity or the capacity of any entity/universe of reflection or comprehension. ”The virtual particles” are a nonsense, (such as light is a nonsense as a wave-particle, but a non-matter particle), if we take a close look at the classical conventions of the dictionary, according to which these are,

”A very small part from a substance, from a matter”

Matter cannot be both virtual and real at the same time. The ether cannot be virtual, as long as it gives shape to matter. We can only extrapolate the matter/energy that exists and that we can reflect in the world we live in. An entity/universe exists or it does not exist. If we were to consider the ether to be another form of existence beyond the matter/energy, we would go to ridiculousness. That would mean that the ether does not belong to this world, either because it cannot be reflected, or because it does not exist. The ether exists beyond the space/time dimension around us. 

@John Macken,

We know the main problem of general relativity where the gravitation is connected with the metric and geometric space has additional physical property to be curved near of massive bodies. It is too complex for understanding and we need to simplify the model. The Le Sage’s model of gravitation is a great theory where the space is only a void where a lot of relativistic particles can generate both gravitation and electromagnetic interaction between bodies. The Lorentz factor, the mass and charge of the particles can be calculated as far as their space energy density. The modernized Le Sage’s model take off the problems of the model describing the way of interaction of particles of force vacuum field with the matter. As such the aether is the vacuum field of relativistic particles.

https://www.researchgate.net/publication/284032224_The_Graviton_Field_as_the_Source_of_Mass_and_Gravitational_Force_in_the_Modernized_Le_Sage%27s_Model

https://www.researchgate.net/publication/308515309_The_charged_component_of_the_vacuum_field_as_the_source_of_electric_force_in_the_modernized_Le_Sage%27s_model

Article The Graviton Field as the Source of Mass and Gravitational F...

Article The charged component of the vacuum field as the source of e...

Einstein changed the definitions of the ether to be identical to his view of space time continuum. Then he used it to defend his theory, gradually omitting it when defense was no longer necessary. 

The Leiden lecture of 1920 contains the complete development of his thought on ether and the history that led to it.

aether/ether is nothing but the same thing with another name. this happening is like: Shakespeare didn`t write his work, it was another person merely named Shakespeare (too).

The answer to the original question is positive.  The GR spacetime is simply one interpretation of the Einstein equations.  A Lorentz ether interpretation is possible too. See http://ilja-schmelzer.de/ether for the ether interpretation of the Einstein equations. It can be understood as a limiting case of another ether theory, which solves many problems of GR, namely it has local energy and momentum densities for the gravitational field too.  And, given that we know how to quantize condensed matter theories, it can be easily quantized.  See http://ilja-schmelzer.de/gravity for details.  This is not some crank ether nonsense, this is published in mainstream journals. 

"Do these fields physically exist in spacetime? If so, can they be described physically and collectively described as a relativistic aether?"

They can. For an ether theory which realizes this for all the fermions and gauge fields of the standard model as well as for the gravitational field see http://ilja-schmelzer.de/matter for the SM and http://ilja-schmelzer.de/gravity for gravity. Note: this is a published theory, in Foundations of Physics, not the usual crank science related with "ether theories".

>>>For example, in 1934 he wrote “Physical space and the ether are different terms for the same thing; fields are physical states of space.”

>>>"This is probably what Einstein was referring to when he said that "fields are physical states of space" and you could call the spacetime, from this point of view, the ether."

>>>Antoine wrote: In the context of that view spacetime is not an element of nature, it is an element of the way we understand and describe nature. Therefore, it cannot play an active role in the natural phenomena and processes and it cannot possess the properties of a “relativistic aether”.

Effectively for Einstein to have remained true to himself, he would have to have developed a theory of space and not spacetime. But he could not find a formulation of gravity independent of time, so he created the geodesics. The central conceptual problem that we have ever faced in physics is a description of motion independent of time, because we need a static anchor to start describing motion. Space in our minds must be static, and the most Einstein has done with it is to make it experience stress and geometry. So it must behave like an “aether” medium that acts like a container to scalar-mass. Space, however, is NOT static. It is autogenic, auto-dynamic and eternally defoliates. To begin to understand how that works is to think of single point of potential that can experience an infinite suite of harmonic jostling, and yet appear to be stationary or in the likes of a singlet: Fourier at its best understanding. Motion does not need time, nor does it need a static anchor, if you understand that space is natively space momentum. This vision obliterates the concept of medium and finds that the active spread of space creates the different scales or Shells of matter, from the quantum parcels to the cosmic realms, in a single unifying deployment of the VOID. Only that at each scale or Shell it has a different signature.

I discuss these views with numerical support in details in my paper: Time-free Description of Motion in Dynamic Systems from Momentum to Entanglement.

Article Time-Free Description of Motion in Dynamic Systems From Mome...

I can see only a lot of confusion

The aether that was assumed to exist for the propagation of EM waves was removed and with this the hypothesis that the speed of light is constant in all inertial RFs' became possible. This allowed the development of the STR. however, for the GTR, Einstein needed space that curves. if space is void then this is not possible as void has no intrinsic properties. the QM does not need curved space, it works quite well with void, even with the existence of Quantum Foam. In this way Einstein re-introduced an aether, through the back door, for his GTR. This is also the biggest obstacle to unify QM and GTR. Even if we accept that GWs' do exist, it does not prove that the space is filled with an aether or even that GTR is correct. This is similar to the EM waves and the aether that carried them. it was shown that we do not need an aether for the EM waves to exist and propagate. In fact the absolute requirement of an "aether" for GTR is it's greatest weakness and the cause of it's failure if we want to unify gravity with the other forces. The QM is the way to understand our universe and has been successful in unifying three of the four (i am considering the EM as a single force) forces. Therefore, to unify gravity with these three forces we have to give up GTR. thanks.

John, the speed of light is a property of space. Everything that lacks rest mass travels at light speed, a type of symmetry. Time doesn't pass.

Time does pass for a rest mass traveling less than light speed. According to Richard Feynman in QED time goes backward for antimatter. So symmetry is preserved when matter and antimatter are created in pairs.

Higgs is claimed to break the symmetry but at enormous energy.

For your question the answer is probably yes, but with additional properties of polarizable vacuum.

Mustafa, even if I agree with your conclusion, that GR is the weak point which has to be changed to get quantum gravity, I completely disagree with your justification. Not the few remains of the ether in GR cause some problems, but the rejection of the ether. We know how to quantize classical condensed matter theories. GR interpreted consequently as an ether theory, that means as a theory of some classical condensed matter in a classical Newtonian background of space and time, could be easily quantized following standard condensed matter textbooks.

dear Jerry: nothing travels at light speed, but limited by c!

No. In special relativity there isn't any privileged reference frame, nor is there any in general relativity, either. In fact, in general relativity, spacetime, as described by the metric tensor, isn't a physical object at all, since the metric changes under general coordinate transformations.

Particles are excitations of the corresponding field, defined with respect to a vacuum state. Such a state is globally defined in flat spacetime, not, however, in curved spacetime. Scalar fields are the only fields that can have constant values, however.

Gravitational waves are ``ripples in spacetime'' and are, equally well, superpositions of a large number of gravitons (since gravitational waves are classical objects, whereas gravitons are not). It isn't trivial, but possible, to define physical observables for gravitational waves.

“…In special relativity there isn't any privileged reference frame, nor is there any in general relativity, either.…”

yeah, that is indeed so, in the SR/GR it is postulated that there is no the absolute Matter’s spacetime and all/every reference frames are totally and completely equivalent, so are totally and completely legitimate. Thus indeed in theSR/GR “there isn't any privileged reference frame”.

However from these postulates evidently, directly, and unambiguously, any number of evidently absurd physical consequences follow.

An example – from that every reference frame is completely legitimate directly and unambiguously follows, that if really simultaneously there are a number of differently relatively moving, say, inertial reference frames, then quite legitimately simultaneously really there exist equal number of Matters and Matters’ spacetimes, where the spacetimes and material objects inside the spacetimes, are differently “contracted”, “dilated”, etc.

Or if some observer start move on a highway with a speed, say, 100 mph, then, since in his frame, where he is at rest, all Matter moves with the speed 100 mph, then he, using a few liters of benzene, really forces an unbelievable Matter’s mass really to move with this speed, etc., etc., etc.

Such evidently absurd and unambiguously following from the SR/GR consequences seems are tabooed in the true SR/GR believers brains on some sub-conscious level, so “officially” usually only two such consequences are discussed “the Dingle problem of the SR” [though that is the same as the consequences above], which is quite evident and so is “solved” in the “official” physics by massive repetitions of the mantra “Dingle is wrong”; though he is, of course, right; and the “twin paradox”.

This paradox is nothing else then revelation of the Dingle problem two times [motion of the twin-traveler forth and back], and so cannot be solved in framework of the SR principally also, though in this case there are much more possibilities by using some complicated calculations, etc. to imitate a “solution”. Nonetheless, quite naturally all these existent “solutions” simply always use some tricks, at that the more a solution is in accordance with the SR/GR, the more absurd the solution is; more in this case see https://www.researchgate.net/publication/322798185_The_informational_model_twin_paradox DOI 10.13140/RG.2.2.34064.51201/1 (01.02.18)

From the consequences above by the proof by contradiction immediately, directly and unambiguously follows, that the SR/GR postulates above aren’t correct and have no relation to the objective reality; Matter’s spacetime is absolute and real [mathematically] manifold.

Besides, from Shevchenko and Tokarevsky “The Information as Absolute” conception https://www.researchgate.net/publication/260930711_the_Information_as_Absolute DOI 10.5281/zenodo.268904

follow the correct definitions of the notions/phenomena “Space” and “Time”, from which follows, that the Matter’s spacetime is nothing more then an empty container, where the informational system “Matter” exists and changes, and it by any means cannot be impacted/ cannot be transformed by anything inside; the postulated in the SR/GR transformations of the spacetime are nothing else then some fantasies; etc.

Thus, returning to this thread question more concretely, from the points above in this post there are a few remarks:

First of all the question “Does spacetime possess the properties of a "relativistic aether"?” is incorrect, Matter’s spacetime has only one property: it is principally uniform emptiness, in which anything material can be placed, however which principally cannot at that possess anything. Including in the spacetime, which is [5]4D Euclidian emptiness can be placed the 4D ether, which can be uniform, as the spacetime is.

In the Shevchenko and Tokarevsky informational model https://www.researchgate.net/publication/273777630_The_Informational_Conception_and_Basic_Physics DOI 10.5281/zenodo.16494

it is postulated, that such ether indeed exists, as the dense lattice of the fundamental logical elements (FLE), where all/every material objects is/are some disturbances of the lattice, which constantly move in the lattice with 4D speeds of light. Besides that allow to develop rather reasonable model of Gravity [which isn’t of course some mystic “curvature” of really non-existent, of course, imaginary [mathematically] 4D pseudo Riemannian space], etc.

More see the papers linked above; besides there are a number of threads, where some relevant to this thread problems are considered. By some regrettably known reason, these threads disappeared from the question threads’ menus, and even seems from notifications [though from that now possibly there are some exclusions, in the thread’s option [“Question followers” -> “See all”] the option “See all” doesn’t work now and so names of the followers are secret, rather possibly that some followers are notified]:

https://www.researchgate.net/post/Why_are_scientists_trying_to_merge_gravity_and_quantum_physics_even_though_gravity_is_just_the_curvature_of_space-time?view=5acbb915b0366deaf33cffd9

https://www.researchgate.net/post/What_is_the_actual_physical_meaning_of_the_Lorentz_Transformations?view=5acb800493553b3b5a0899e4

https://www.researchgate.net/post/Could_we_consider_anti-particles_as_having_negative_mass?view=5addc447337f9f1f6760e64c

https://www.researchgate.net/post/Does_the_gravitational_wave_detection_is_real?view=5ad3504c217e204ba31e2ba3

https://www.researchgate.net/post/Does_The_Long_Range_Of_Gravity_Require_Any_Graviton_To_Be_Massless

https://www.researchgate.net/post/Is_gravity_a_dark_energy_effect

Cheers

The ether as a material medium that occupies the vacuum and that would explain the propagation of electromagnetic waves does not exist. But the modern concepts that replace it are much more abstract: space-time and wave-particle duality. In particular, light's propagation in a vacuum is attributable to the behaviour of light as a particle; no need of an ether.

@Enrique Cantera del Río

The modern ether explains more than electromagnetic waves, namely all particles and gauge fields of the standard model of particle physics ( http://ilja-schmelzer.de/matter ) and gravity ( http://ilja-schmelzer.de/gravity ) as well. This is not a dream, but an article published in a mainstream journal, I. Schmelzer, A Condensed Matter Interpretation of SM Fermions and Gauge Fields, Foundations of Physics, vol. 39, nr. 1, p. 73 (2009), resp. arxiv:0908.0591.

The modern concept, which is simply field theory, explains nothing - it is a claim that we do not need any explanations. If one would have accepted this in the past, temperature would be even today only a field. Quantum physics (wave-particle duality) is quite irrelevant, we have quantum theory of former classical condensed matter theories too, and quantum theory would be applicable to an ether theory in a similar way, following the same well understood techniques.

@ Ilja Schmelzer

"... it is a claim that we do not need any explanations..."

I do not think so : wave-particle duality is the concept that needs an explanation; in particular the wave-collapse.