Through what medium does EM propagate in empty space?

[Haelfix]

The problem is that the observed vacuum energy isn't zero, its unimaginably small but positive.

I actually don't mind thinking of it as a 'medium', but it most certainly is nothing like a classical 'medium'. Its also an approximation in some sense, the polarization induced by off mass shell particle pairs might just be a relic of perturbation theory. I suppose it wouldn't be far fetched too say 'well if I had a nonperturbative description' then this is simply *the* say electron field that exists throughout all spacetime. There *is* no propagation in a strict global sense as that is simply an artifact of a choice of local trivialization (a gauge choice).

A lot of these sorts of questions come up even in the classical GR theory (if I instantenously remove this star, what *is* propagated and what does it *mean* for spacetime). Of course the paradoxes are instantly resolved once you realize that you can't simply *remove* a star like so and that the problems arise because you are looking only at a local picture and trying to make a unphysical generalization to the global view.

Either way its semantics and philosophy, if your theory doesn't make any new falsifiable predictions and instead simply reformulates everything, its more or less irrelevant.

 

[turbo]

Either way its semantics and philosophy, if your theory doesn't make any new falsifiable predictions and instead simply reformulates everything, its more or less irrelevant.

See post #44 and after for predictions, including an explanation of the Pioneer effect.

As for the value of the observed vacuum energy, if you believe that cosmological redshift is due to the expansion of the universe, you need a small cosmological constant. If cosmological redshift is due to EM's interaction with the vacuum field, the Universe can be a steady-state universe (the one Einstein created GR to explain) and there is no need for a CC.

 

[Haelfix]

"if you believe that cosmological redshift is due to the expansion of the universe, you need a small cosmological constant"

No you don't, you can write down a cosmological redshift for a flat robertson walker universe just fine, and you can see rather trivially it has absolutely *nothing* to do with any interaction with an EM field. In fact, the functional form of the csomological redshift has no relationship to the scale parameter whatsoever (exercise: prove it)

Further, the steady state universe is experimentally rejected on many grounds.

 

[turbo]

"if you believe that cosmological redshift is due to the expansion of the universe, you need a small cosmological constant"

No you don't, you can write down a cosmological redshift for a flat robertson walker universe just fine, and you can see rather trivially it has absolutely *nothing* to do with any interaction with an EM field. In fact, the functional form of the csomological redshift has no relationship to the scale parameter whatsoever (exercise: prove it)

Further, the steady state universe is experimentally rejected on many grounds.

Maybe you can explain. If the gravitational material in the universe is unable to slow the expansion of the Big Bang model and if the gravitational equivalence of the vacuum energy is unable to do so, don't you NEED a positive cosmological constant to provide the expansive pressure needed to provide the accelerating cosmological expansion that physicists who adhere to the standard model believe in?

 

[Jonny_trigonometry]

suppose that the universe can be modeled with an absolute space with which everything referances, wouldn't SR not work?

Suppose everything can be referanced to an absolute space-time, then SR would still work right? what about GR?

If everything isn't referanced to space, then there is no aether, but then how can light that is being emmitted from something be independant of the speed of the emmitter?

 

[Haelfix]

Maybe you can explain. If the gravitational material in the universe is unable to slow the expansion of the Big Bang model and if the gravitational equivalence of the vacuum energy is unable to do so, don't you NEED a positive cosmological constant to provide the expansive pressure needed to provide the accelerating cosmological expansion that physicists who adhere to the standard model believe in?

Theres nothing wrong with what you said, yes you need a CC to *accelerate* the expansion, but that has strictly nothing to do with cosmological redshift. You will have cosmological redshift with a negative cc for instance.

Otoh, luminosity *is* for instant, very sensitive to scale parameter effects. It very much matters if k = -1, as opposed to k = 1, for certain values of z.

All this is covered in any introductory text on GR and cosmology.

 

[turbo]

suppose that the universe can be modeled with an absolute space with which everything referances, wouldn't SR not work?

Suppose everything can be referanced to an absolute space-time, then SR would still work right? what about GR?

Well, Einstein thought that an absolute reference frame is required by GR gravity. He also insisted that it be a dynamical entity. In his 1920 Leyden address, he had not connected the EM ether to the gravitational ether, but still aknowledged the necessity for an all-pervasive EM ether to allow the transmission of EM across "empty" space.

If everything isn't referanced to space, then there is no aether, but then how can light that is being emmitted from something be independant of the speed of the emmitter?

A key point! Without a transmissive medium enforcing the "speed limit", the propagation rate of EM waves would be dependent on the relative velocities of the emitter and observer.

Back to my initial question - through what medium does EM propagate across empty space? You know what I believe that medium to be. Are there alternative views?

 

[Garth]

Well, Einstein thought that an absolute reference frame is required by GR gravity.

Is not this statement a complete contradiction of everything Einstein stood for in his works on relativity theory? The very basis of his approach was that there should be no absolute or preferred frame of reference. His problem in wanting to fully incorporate Mach's Principle was the MP does give grounds to select a frame, the one co-moving with the Centre of Mass/Momentum (comoving centroid) of the rest of the universe. As a consequence it is acknowledged that GR does not fully incorporate MP.

Garth

 

[turbo]

Is not this statement a complete contradiction of everything Einstein stood for in his works on relativity theory? The very basis of his approach was that there should be no absolute or preferred frame of reference. His problem in wanting to fully incorporate Mach's Principle was the MP does give grounds to select a frame, the one co-moving with the Centre of Mass/Momentum (comoving centroid) of the rest of the universe. As a consequence it is acknowledged that GR does not fully incorporate MP.

Garth

I think that is is commonly assumed that Einstein's relativity theories put the ether to death. While it is true that some people found it easier to abandon the concept of an ether and embrace field theories, Einstein needed to incorporate the ether concept to advance beyond GR. His motivation? He had a real problem with the concept of inertia and found that to avoid impossible "action at a distance", the apparent resistance of mass to acceleration had to arise locally, from interaction with the ether. In addition, his ether has dynamical interactions with embedded matter. See bold text.

The special theory of relativity forbids us to assume the ether to consist of particles observable through time, but the hypothesis of ether in itself is not in conflict with the special theory of relativity.

Only we must be on our guard against ascribing a state of motion to the ether.

Certainly, from the standpoint of the special theory of relativity, the ether hypothesis appears at first to be an empty hypothesis. In the equations of the electromagnetic field there occur, in addition to the densities of the electric charge, only the intensities of the field. The career of electromagnetic processes in vacuo appears to be completely determined by these equations, uninfluenced by other physical quantities. The electromagnetic fields appear as ultimate, irreducible realities, and at first it seems superfluous to postulate a homogeneous, isotropic ether-medium, and to envisage electromagnetic fields as states of this medium.

But on the other hand there is a weighty argument to be adduced in favour of the ether hypothesis.

To deny the ether is ultimately to assume that empty space has no physical qualities whatever.

The fundamental facts of mechanics do not harmonize with this view. For the mechanical behaviour of a corporeal system hovering freely in empty space depends not only on relative positions (distances) and relative velocities, but also on its state of rotation, which physically may be taken as a characteristic not appertaining to the system in itself.

In order to be able to look upon the rotation of the system, at least formally, as something real, Newton objectivises space.

Since he classes his absolute space together with real things, for him rotation relative to an absolute space is also something real. Newton might no less well have called his absolute space "Ether"; what is essential is merely that besides observable objects, another thing, which is not perceptible, must be looked upon as real, to enable acceleration or rotation to be looked upon as something real.

It is true that Mach tried to avoid having to accept as real something which is not observable by endeavouring to substitute in mechanics a mean acceleration with reference to the totality of the masses in the universe in place of an acceleration with reference to absolute space. But inertial resistance opposed to relative acceleration of distant masses presupposes action at a distance; and as the modern physicist does not believe that he may accept this action at a distance, he comes back once more, if he follows Mach, to the ether, which has to serve as medium for the effects of inertia. But this conception of the ether to which we are led by Mach's way of thinking differs essentially from the ether as conceived by Newton, by Fresnel, and by Lorentz. Mach's ether not only conditions the behaviour of inert masses, but is also conditioned in its state by them.

Mach's idea finds its full development in the ether of the general theory of relativity.

 

[Hans de Vries]

Back to my initial question - through what medium does EM propagate across empty space? You know what I believe that medium to be. Are there alternative views?

There is a lot more one can say here, by using first principles.

This is my personal take on “The Medium” :


EM propagation is only a degenerated (mass less) case of the more general
quantum field. Any explanation in terms of media should take in account
that all fields/forces are equally subject to SR/GR. If SR/GR is determined
by a medium then this mechanism is more likely to occur at a level "deeper",
that is, where there is unification.

The clues from e^{-iEt/\hbar}\ \ ….

One can try to assign a physical interpretation to the term above like
vibration, spin or precession. A free relativistic (say Klein-Gordon) wave-
packet in its rest-frame will have a phase which is equal over all of space.
The deBroglie wave length is infinite at rest. A finite deBroglie wave-
length is only seen in reference frames other then the rest frame as a
result of the non simultaneity of SR.

( see for instance here, in tutorial style ) :
the relativistic kinematics of the wave packet

It is this synchronization of phase over all space which gives us important
clues. Such a synchronization is only possible with a repetitive signal. This
leads us to the investigation of spin-lock in 3 dimensions. The (discrete)
components of a medium propagate their own phase to all their neighbors
with velocity c. The neighbors must all lie at distances which are integer
multiples of the wavelength in order to establish synchronization. Only in
this case they will all have equal phase.

This requirement of integer multiples is trivial to fulfill in 1D but impossi-
ble in 2D and 3D. There’s simply no regular grid in 3D that fulfills this.
It becomes easier however if the average distance is much larger then the
wave-length (n >> 1) and its easier to find an optimal location. This leaves
precession as the only physical interpretation of phase (from the three
mentioned) since the Compton wavelength is much to coarse to fulfill this
requirement.

So we could interpret the phase frequency as a precession of a spin at
much higher frequency and much shorter wave length somewhere in the
direction of Planck’s scale and Planck’s frequency. A (single?) spin
frequency at Plank scale might give rise to the multiplicity of (precession)
frequencies as we see them. There are at least 3 space dimensions
required for precession to occur.

Then there is a second prescription required by phase synchronization:
All components of the medium (say particles) that are synchronized to
each other, and have the same phase, must be at rest in respect to each
other! Now in a typical vacuum however you would expect to see
things at all kinds of speeds ranging from zero to c.

The second prescription splits the single medium into many media, one
for each velocity and its direction. Two waveforms of different energy can
coexist both synchronized in their own rest frame while perceiving the
synchronization signals of the other as high frequency noise. We can see
here a physical explanation of Pauli’s exclusion principle for particles
with the same energy.

One can show, just using standard SR and QM math that if a wave-packet
Has any physical meaning that the medium incorporating it should have
The same physical speed a the particle embodied by the wave-packet.
The synchronization requirement simply picks those elements of the
media which happen to have a near equal speed.

Again, see here: the relativistic kinematics of the wave packet

This directly satisfies the requirement of SR that the laws of physics are
equal in different reference frames even though we have a medium. In a
different reference frame a different subset of the medium is selected:
The subset that moves at the required speeds and directions to enable the
synchronization of the QM phases.

If we now go back to EM propagation then it would be no more than logical
to expect that photons and their EM wave function (and thus their medium)
also move at the same speed, that is, the speed of light. This presents us
the typical Einsteinian picture where particles, including photons, move
with the speed they have (including their wave-packet) instead of being
waves in a medium.

The *propagation* through a medium nevertheless plays an essential role,
but indeed at a level lower at which we can assume that unification has
occurred. We need something to communicate the phases for our subsets
of the vacuum in order to achieve synchronization. This has to be a level
lower since it communicates phase *between* the constituents of what
we have called “the medium” until now.

This finally would then be what bestows the limit of c upon us. Physical
wave-packets can not move faster then c because the synchronization
mechanism falters beyond it.


Regards, Hans

 

[turbo]

For those that have not read Einstein's Leyden address:

According to this theory the metrical qualities of the continuum of space-time differ in the environment of different points of space-time, and are partly conditioned by the matter existing outside of the territory under consideration. This space-time variability of the reciprocal relations of the standards of space and time, or, perhaps, the recognition of the fact that empty space in its physical relation is neither homogeneous nor isotropic compelling us to describe its state by ten functions (the gravitation potentials gmn), has, I think, finally disposed of the view that space is physically empty. But therewith the conception of the ether has again acquired an intelligible content, although this content differs widely from that of the ether of the mechanical undulatory theory of light. The ether of the general theory of relativity is a medium which is itself devoid of all mechanical and kinematical qualities, but helps to determine mechanical (and electromagnetic) events.

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. Thus we may also say, I think, that the ether of the general theory of relativity is the outcome of the Lorentzian ether, through relativation.

As to the part which the new ether is to play in the physics of the future We are not yet clear. We know that it determines the metrical relations in the space-time continuum, e.g. the configurative possibilities of solid bodies as well as the gravitational fields; but we do not know whether it has an essential share in the structure of the electrical elementary particles constituting matter. Nor do we know whether it is only in the proximity of ponderable masses that its structure differs essentially from that of the Lorentzian ether; whether the geometry of spaces of cosmic extent is approximately Euclidean. But we can assert by reason of the relativistic equations of gravitation that there must be a departure from Euclidean relations, with spaces of cosmic order of magnitude, if there exists a positive mean density, no matter how small, of the matter in the universe. In this case the universe must of necessity be spatially unbounded and of finite magnitude, its magnitude being determined by the value of that mean density.

If we consider the gravitational field and the electromagnetic field from the standpoint of the ether hypothesis, we find a remarkable difference between the two. There can be no space nor any part of space without gravitational potentials; for these confer upon space its metrical qualities, without which it cannot be imagined at all. The existence of the gravitational field is inseparably bound up with the existence of space. On the other hand a part of space may very well be imagined without an electromagnetic field; thus in contrast with the gravitational field, the electromagnetic field seems to be only secondarily linked to the ether, the formal nature of the electromagnetic field being as yet in no way determined by that of gravitational ether. From the present state of theory it looks as if the electromagnetic field, as opposed to the gravitational field, rests upon an entirely new formal motif, as though nature might just as well have endowed the gravitational ether with fields of quite another type, for example, with fields of a scalar potential, instead of fields of the electromagnetic type.

Since according to our present conceptions the elementary particles of matter are also, in their essence, nothing else than condensations of the electromagnetic field, our present view of the universe presents two realities which are completely separated from each other conceptually, although connected causally, namely, gravitational ether and electromagnetic field, or -- as they might also be called -- space and matter.

Of course it would be a great advance if we could succeed in comprehending the gravitational field and the electromagnetic field together as one unified conformation.

Then for the first time the epoch of theoretical physics founded by Faraday and Maxwell would reach a satisfactory conclusion. The contrast between ether and matter would fade away, and, through the general theory of relativity, the whole of physics would become a complete system of thought, like geometry, kinematics, and the theory of gravitation.

Einstein did not kill off the ether with his theories of relativity, but he did constrain its nature and demonstrate the necessity of its existence as a REAL entity.

 

[samalkhaiat]

MOST physics students can formulate Maxwell equations with no reference to the SOLID-ELASTIC ether of the 19th century. Because she/he knows that Einstein's SR abolished the need for such concept. He/she can also solve Maxwell equations in empty space and find that such solution is nothing but EM-field propagating in vacuum with the finite speed C. Now he/she recall that their physics school teacher once told them that E & H are perpendicular to each other and the oscillation of one causes the other to oscillate and the whole thing propagate in the K-direction. However, they are mature students now, so their conclusion about Maxwell vacuum solution IS; "IT MEANS THAT THE EM-FIELD ITSELF ACQUIRES PHYSICALREALITY". i.e such object is as real as Newton's material particle. Except for ancient thinker, nobody questioned the motion of material particle in vacuum in the absence of forces.So your question,in my opinion, is reducible EITHER to the phylosofical question; "why motion is possible?" (I do not want to speculate), OR you are actually asking about the structure of spacetime itself, But this belongs to Quantum Gravity! not to Maxwell or Einstein theories.
It is no accident that the excellent book of Landau & Lif****z (The classical theory of fields) never mentioned the word ETHER.

regards

 

[turbo]

The *propagation* through a medium nevertheless plays an essential role, but indeed at a level lower at which we can assume that unification has occurred. We need something to communicate the phases for our subsets of the vacuum in order to achieve synchronization. This has to be a level lower since it communicates phase *between* the constituents of what we have called “the medium” until now.

This finally would then be what bestows the limit of c upon us. Physical
wave-packets can not move faster then c because the synchronization
mechanism falters beyond it.

Regards, Hans

Thank you, Hans for your detailed posting. I do not have time to address all your points right now and relate them to my model of space-time, but rest assured that I will try to address them.

Note: This thread has been moved again (likely to allow the SR/GR crowd to bash it for a while ) and I want to thank the person(s) who decided to move it. Hopefully, the Cosmology and Quantum folks who have contributed will follow and consider the comments of the SR/GR crowd. The fresh exposure will likely bring some interesting insights from another audience, and we (and I personally) could benefit from a whole lot more of that.

 

[Janus]

This thread has gone nowhere fast.